Sample records for reinforced soil walls

  1. Conventional Weapons Effects on Reinforced Soil Walls.


    of the reinforced soil wall. 14. SUBJECT TERMS 15. NUMBER OF PAGES Reinforced soil, conventional weapons, protective structures, 388 geosynthetics ...high tensile strength materials such as steel strips or geosynthetics . A single face of a reinforced soil berm can be constructed to approximately...yards of geosynthetics representing $3.1 billion have been used in a wide range of civil engineering applications (Koerner, 1990). Between 1991 and 1992

  2. Behavior of granular rubber waste tire reinforced soil for application in geosynthetic reinforced soil wall

    G. G. D. RAMIREZ

    Full Text Available AbstractLarge quantities of waste tires are released to the environment in an undesirable way. The potential use of this waste material in geotechnical applications can contribute to reducing the tire disposal problem and to improve strength and deformation characteristics of soils. This paper presents a laboratory study on the effect of granular rubber waste tire on the physical properties of a clayey soil. Compaction tests using standard effort and consolidated-drained triaxial tests were run on soil and mixtures. The results conveyed an improvement in the cohesion and the angle of internal friction the clayey soil-granular rubber mixture, depending on the level of confining stress. These mixtures can be used like backfill material in soil retaining walls replacing the clayey soil due to its better strength and shear behavior and low unit weight. A numerical simulation was conducted for geosynthetic reinforced soil wall using the clayey soil and mixture like backfill material to analyzing the influence in this structure.

  3. Soil Reinforcement Techniques

    Prashant Patil


    Full Text Available In many activities concerned with the use of soil, the physical properties like Stiffness, Compressibility and Strength are some of the few important parameters to be considered. Of the many methods involved in improvement of soil properties, soil reinforcement is method concerned with increase of strength properties of soil. In soil reinforcement, the reinforcements or resisting element are of different materials and of various forms depending upon the intended use. The reinforcement can be provided permanently or temporarily to increase strength of adjacent structures. The present topic of discussion involves different materials, forms and applications of soil reinforcement

  4. Seismic Stability of Reinforced Soil Slopes

    Tzavara, I.; Zania, Varvara; Tsompanakis, Y.


    Over recent decades increased research interest has been observed on the dynamic response and stability issues of earth walls and reinforced soil structures. The current study aims to provide an insight into the dynamic response of reinforced soil structures and the potential of the geosynthetics...... to prevent the development of slope instability taking advantage of their reinforcing effect. For this purpose, a onedimensional (SDOF) model, based on Newmark’s sliding block model as well as a two-dimensional (plane-strain) dynamic finite-element analyses are conducted in order to investigate the impact...

  5. Seismic Stability of Reinforced Soil Slopes

    Tzavara, I.; Zania, Varvara; Tsompanakis, Y.


    Over recent decades increased research interest has been observed on the dynamic response and stability issues of earth walls and reinforced soil structures. The current study aims to provide an insight into the dynamic response of reinforced soil structures and the potential of the geosynthetics...... to prevent the development of slope instability taking advantage of their reinforcing effect. For this purpose, a onedimensional (SDOF) model, based on Newmark’s sliding block model as well as a two-dimensional (plane-strain) dynamic finite-element analyses are conducted in order to investigate the impact...... of the most significant parameters involved, such as the flexibility of the sliding system, the mechanical properties of the soil and of the geosynthetics material, the frequency content of the excitation and the interface shear strength....

  6. Model test on sand retaining wall reinforced with denti-strip inclusions

    ZHANG MengXi; ZHOU Huai


    In conventional reinforced soil structures, the reinforcements are often laid hori-zontally in the soil. In this paper, a new concept of soil reinforced with denti-strip inclusions was proposed and a series of laboratory model tests were carried out on sand retaining wall reinforced with denti-strip inclusions. Besides the horizontal displacements of the facing, the lateral earth pressures acting on vertical elements were measured. A microscopic measurement was performed to investigate the deformation and progressive failure of the sand within model retaining wall. Based on the image analytical technique, the bearing capability and interaction mecha-nism of reinforced sand retaining wall were analyzed. The model of the initial shear failure and potential failure surface were also put forward. From the ex-perimental results, it is shown that denti-strip inclusions can increase the bearing capability of retaining wall significantly and restrict the facing displacements effi-ciently, as compared with conventional horizontal reinforcement.

  7. Design and Application of Packaged Reinforced Soil Retaining Wall in the Subgrade of Nanjing-Qidong Railway%包裹式加筋土挡墙在宁启铁路路基中的设计与应用

    罗琼; 白楷


    论述了加筋土挡墙基于极限平衡理论的设计方法,以宁启铁路海安枢纽内L1DK0+184.953~+339.410段工程为例,介绍了土工格栅加筋土挡墙的方案比选、拉筋设计,并对其进行内部稳定性和外部稳定性进行检算,包裹式加筋土挡墙良好的施工效果也证明了设计的可靠性。%The paper discusses the design of reinforced soil retaining wall on the basis of limit equilibrium theory. Taking L1DKO + 184. 935 - + 339. 410 section within Haian junction of Nanjing-Qidong Railway as the example, the comparison of geogrid reinforced retaining wall schemes and its reinforcement design are introduced; and then the internal and external stability of the wall is calculated and checked. The good construction effect of the packaged reinforced soil retaining wall also proves the reliability of the design.

  8. Mechanical performance of a double-face reinforced retaining wall in an area disturbed by mining

    YU Guang-yun; BAI Yong-sheng; SHENG Ping; GUO Rui-ping


    The application of a double-face reinforced retaining wall during road construction can reduce engineering costs, speed road paving and have a good influence on environment. An ABAQUS numerical model of a double-face reinforced retaining wall was built. The influence of surface subsidence induced by mining was considered. A physical model test was also performed in the laboratory on a reinforced retaining wall. The influence of subsidence induced by mining was observed. The numerical results match measurements in the laboratory very well. The vertical pressure on the base of the retaining wall, the horizontal displacement of the wall and the horizontal soil pressure acting on the wall were analyzed. The differential settlement of the reinforced belt and axial forces in the wall were also studied.

  9. Behavior of Reinforced Retaining Walls with Different Reinforcement Spacing during Vehicle Collisions

    Kwangkuk Ahn


    reinforcement spacing using LS-DYNA, a general finite-element program. Eight tons of truck weight was used for the numerical analysis model. The behavior of a reinforced retaining wall under variable reinforcement spacing and positioning was analyzed. The results indicated that the reinforcement material was an important resistance factor against external collision load.

  10. Mechanism of Reinforcement on Inwall of Coal Mine Shaft Wall

    Jinlong Liu


    Full Text Available Based on the theory of elasticity, the analytic solution of temperature stress on shaft wall of coal mine with reinforcement on inwall is deduced. It is shown that with the increment of reinforcement stress Pa, the radial compressive stress &sigmar become larger, the vertical compressive stress &sigmaz become less, while the circumferential stress &sigma &theta changed from compressive stress to tensile stress. The stability of shaft wall enhanced with vertical stress reduced by reinforcement on inwall of shaft wall. Compressive steel plate could be used to reinforce the inwall, characterized with low-cost, short time and construction easy. While the intelligent equipment should be developed further to provide everlasting and greater reinforcement on in wall of coal mine shaft wall.

  11. Mechanism of Reinforcement on Inwall of Coal Mine Shaft Wall

    Jinlong Liu; Luwang Chen; Jili Wang


    Based on the theory of elasticity, the analytic solution of temperature stress on shaft wall of coal mine with reinforcement on inwall is deduced. It is shown that with the increment of reinforcement stress Pa, the radial compressive stress &sigmar become larger, the vertical compressive stress &sigmaz become less, while the circumferential stress &sigma &theta changed from compressive stress to tensile stress. The stability of shaft wall enhanced with vertical stress reduced by reinforcement...

  12. Model test on sand retaining wall reinforced with denti-strip inclusions


    In conventional reinforced soil structures,the reinforcements are often laid hori-zontally in the soil.In this paper,a new concept of soil reinforced with denti-strip inclusions was proposed and a series of laboratory model tests were carried out on sand retaining wall reinforced with denti-strip inclusions.Besides the horizontal displacements of the facing,the lateral earth pressures acting on vertical elements were measured.A microscopic measurement was performed to investigate the deformation and progressive failure of the sand within model retaining wall.Based on the image analytical technique,the bearing capability and interaction mechanism of reinforced sand retaining wall were analyzed.The model of the initial shear failure and potential failure surface were also put forward.From the experimental results,it is shown that denti-strip inclusions can increase the bearing capability of retaining wall significantly and restrict the facing displacements efficiently,as compared with conventional horizontal reinforcement.

  13. 生态挡土结构面层与加筋连接强度的试验研究%Experimental study on connection strength between soil bag surface and reinforced geotextile for ecological retaining wall

    蓝日彦; 王保田; 魏军扬; 赵波


    The flexible soil bag reinforced retaining structure has low requirement for the bearing capacity of the foundations. This kind of retaining wall is suitable for foundations and can form green retaining wall or slope. It is a kind of ecological retaining wall which presents harmony between engineering structure and surrounding environment. The connection strength between soil bag face and the geotextile is the key to the stability of the ecological retaining walls. The connection strengths between soil bag face and the geotextile and between filling soil and the geotextile have been obtained by laboratory tests. The results show that the friction angles between soil bag face and the geotextile are 9° ~ 15° for different soils filled into the soil bags, which is much smaller than the friction angle between soil bag faces (above 20°). A new connection style of reverse package has been put forward to overcome the problem of low connection between soil bag face and the geotextile. The friction strength between the soil bag face and the geotextile with the reverse package connection is higher than that between soil bag faces. The reverse package method can overcome the slide failure along the interface of soil bag and geotextile. The test results show that the shear strength (friction strength) between soil bags has significant difference with different filling soils. The friction angle of soil bag face is 20.4° when red clay is filled and 25.5° when gravel is filled.%生态袋加筋柔性挡土结构对地基承载力要求低,具有良好的地基条件适应性,并可以形成绿色挡土墙或边坡,是工程措施与自然和谐共存的一种挡土结构形式.生态袋面层和面层后填土与加筋格栅的连接强度大小,是控制生态挡土结构稳定性的关键.采用室内试验的方法,研究生态袋和填土与加筋格栅的连接强度,结果表明:生态袋与加筋格栅界面摩擦角仅在9°-15°,远小于生态袋间的界面摩擦

  14. Thin-walled reinforcement lattice structure for hollow CMC buckets

    de Diego, Peter


    A hollow ceramic matrix composite (CMC) turbine bucket with an internal reinforcement lattice structure has improved vibration properties and stiffness. The lattice structure is formed of thin-walled plies made of CMC. The wall structures are arranged and located according to high stress areas within the hollow bucket. After the melt infiltration process, the mandrels melt away, leaving the wall structure to become the internal lattice reinforcement structure of the bucket.

  15. Centrifuge modelling and finite element analysis of reinforced fly ash walls

    Mandal, J.N.; Shaikh, Z. [Indian Institute of Technology, Bombay (India). Dept.of Civil Engineering


    Centrifuge modeling of unreinforced and reinforced fly ash wall was done with varying water content to study the failure pattern and their behaviour. Fly ash was from the ash disposal pond of Koradi Thermal Power Plant (KTPP) in Nagpur, India. The fly ash walls without reinforcement are liable to fail and sudden failure of slopes have been noticed. Unreinforced fly ash wall shows a sharp decrease in the strength for a water content on the higher side of optimum moisture content. Fly ash walls reinforced with geotextiles performed satisfactorily even at very high rpm. A non-linear finite element analysis was carried out to evaluate the distribution of stresses and deformations. The lateral deformation obtained by the finite element analysis and the centrifuge modeling is found to be sufficiently less than the permissible limit. The lateral deformations of the reinforced retaining wall does not decrease appreciably with increase in the stiffness of reinforcement but decreases as the modulus of the backfill soil increases. More research is required on the long-term mechanical and chemical behaviour of the fly ash material and the long-term stability of the reinforced fly ash walls. 14 refs., 3 tabs.

  16. How vegetation reinforces soil on slopes

    Stokes, A.; Norris, J.E.; van Beek, L.P.H.; Bogaard, T.; Cammeraat, E.; Mickovski, S.B.; Jenner, A.; Di Iorio, A.; Fourcaud, T.; Norris, J.E.; Stokes, A.; Mickovski, S.B.; Cammeraat, E.; van Beek, R.; Nicoll, B.C.; Achim, A.


    Once the instability process e.g. erosion or landslides has been identified on a slope, the type of vegetation to best reinforce the soil can then be determined. Plants improve slope stability through changes in mechanical and hydrological properties of the root-soil matrix. The architecture of a pl

  17. Fundamentals of fibre-reinforced soil engineering

    Shukla, Sanjay Kumar


    This book is intended to serve as a one-stop reference on fibre-reinforced soils. Over the past 30-35 years, the engineering behaviour of randomly distributed/oriented fibre-reinforced soil, also called simply fibre-reinforced soil, has been investigated in detail by researchers and engineers worldwide. Waste fibres (plastic waste fibres, old tyre fibres, etc.) create disposal and environmental problems. Utilization of such fibres in construction can help resolve these concerns. Research studies and some field applications have shown that the fibres can be utilized in large quantities in geotechnical and civil engineering applications in a cost-effective and environmentally friendly manner. This book covers a complete description of fibres, their effects when included within a soil or other similar materials such as the fly ash, and their field applications. It gives a detailed view of fibre-reinforced soil engineering. The book will be useful to students, professional, and researchers alike, and can also ser...

  18. Seismic response of reinforced soil slopes

    Tzavara, Ioanna; Zania, Varvara; Tsompanakis, Yiannis


    The main aim of the current study is to assess the dynamic response of reinforced soil structures taking into account the most important aspects of the problem and to compare the available design methods. For this purpose, initially the most commonly used pseudostatic approach is implemented via...

  19. Seismic Behaviour of Reinforced Concrete Slit Shear Walls Energy Dissipators

    Sergiu Băetu


    Full Text Available The types of slit walls energy dissipators, from monolith or precast reinforced concrete, proposed by researchers and the seismic behaviour of these types of walls are described. The overall ductility of the structure increases, considering the energy dissipation solutions proposed by the researchers of the reinforced concrete walls, resulting a supplementary safety for the structure. The objective of these solutions is to create an ideal structure for tall multi-storey buildings, that behaves as a rigid structure at low seismic action and turns into a flexible one in case of a high intensity earthquake action. The solutions for increasing ductility proposed in this paper are viable and easily to use in constructions practice. For the analysis of slit wall, the researchers used a series of analytical calculation methods, among the most important being the equivalent frame method and the finite element method, both presented s. 3 of the paper. The researchers concluded that by using this calculations methods, the dynamic behaviour of the reinforced concrete slit walls can be simulated very accurate and realistic.

  20. Analysis of Dynamic Coupling Characteristics of the Slope Reinforced by Sheet Pile Wall

    H. L. Qu


    Full Text Available Large deformation of slope caused by earthquake can lead to the loss of stability of slope and its retaining structures. At present, there have been some research achievements about the slope reinforcement of stabilizing piles. However, due to the complexity of the structural system, the coupling relationship between soil and pile is still not well understood. Hence it is of great necessity to study its dynamic characteristics further. In view of this, a numerical model was established by FLAC3D in this paper, and the deformation and stress nephogram of sheet pile wall in peak ground motion acceleration (PGA at 0.1 g, 0.2 g, and 0.4 g were obtained. Through the analysis, some conclusions were obtained. Firstly, based on the nephogram of motion characteristics and the positions of the slip surface and the retaining wall, the reinforced slope can be divided into 6 sections approximatively, namely, the sliding body parts of A, B, C, D, and E and the bedrock part F. Secondly, the deformation and stress distributions of slope reinforced by sheet pile wall were carefully studied. Based on the results of deformation calculation from time history analysis, the interaction force between structure and soil can be estimated by the difference of peak horizontal displacements, and the structure-soil coupling law under earthquake can be studied by this approach.


    Weifeng SONG; Lihua CHEN; Xiuping LIU


    Roots affect the soil stress and strain and contribute to soil reinforcement. An analysis of stress and strain in the root-soil composite is presented which combines roots, soils, and an interface element by using the Duncan-Chang E-μmodel and a nonlinear-interface-element model. In this research, a finite element numerical analysis method was applied to simulate the stress field resulting in a composite of Pinus tabulaeformis roots and soils. Results show that roots can transmit the stress from surface soils to deep soils, and can reduce soil stress within the surface soil layer; results also show that the effect of soil reinforcement by roots is limited to surface soils. The Slope Safety Index of a pine slope becomes 10% higher than that of a natural slope, indicating that roots have a significant effect on soil reinforcement.

  2. Large-scale direct shear testing of geocell reinforced soil


    The tests on the shear property of geocell reinforced soils were carried out by using large-scale direct shear equipment with shear-box-dimensions of 500 mm×500 mm×400 mm (length×width×height).Three types of specimens,silty gravel soil,geoceli reinforced silty gravel soil and geoceli reinforood cement stabilizing silty gravel soil were used to investigate the shear stress-displacement behavior,the shear strength and the strengthening mechanism of geocell reinforced soils.The comparisons of large-scale shear test with triaxial compression test for the same type of soil were conducted to evaluate the influences of testing method on the shear strength as well.The test results show that the unreinforced soil and geocell reinforced soil give similar nonlinear features on the behavior of shear stress and displacement.The geocell reinforced cement stabilizing soil has a quasi-elastic characteristic in the case of normal stress coming up to 1.0 GPa.The tests with the reinforcement of geocell result in an increase of 244% in cohesion,and the tests with the geocell and the cement stabilization result in an increase of 10 times in cohesion compared with the unreinforced soil.The friction angle does not change markedly.The geocell reinforcement develops a large amount of cohesion on the shear strength of soils.

  3. The Shrinkage Cracking Behavior in Reinforced Reactive Powder Concrete Walls

    Samir A. Al-Mashhadi


    Full Text Available In this study, the reduced scale wall models were used (they are believed to resemble as much as possible the field conditions to study the shrinkage behavior of reactive powder concrete (RPC base restrained walls. Six base restrained RPC walls were casted in different length/height ratios of two ratios of steel fiber by volume in Summer. These walls were restrained by reinforced concrete bases to provide the continuous base restraint to the walls. The mechanical properties of reactive powder concrete investigated were; compressive strength between (75.3 – 140.1 MPa, splitting tensile strength between (5.7 – 13.9 MPa, flexural tensile strength (7.7 – 24.5 MPa, and static modulus of elasticity (32.7 – 47.1GPa. Based on the observations of this work, it was found that the cracks did not develop in the reduced scale of the reactive powder concrete (RPC walls restrained from movement at their bases for different L/H ratios (2, 5, and 10 and for two ratio of steel fiber (1% & 2% during 90 days period of drying conditions. Moreover, the shrinkage values increase toward the edges. Based on the results of this work, the increase in the maximum shrinkage values of walls with 1% steel fiber were (29%, 28%, 28% of the maximum shrinkage values of walls with 2% steel fiber of length/height ratios of (2, 5, and 10 respectively. The experimental observation in beam specimens showed that the free shrinkage, tensile strain capacity and elastic tensile strain capacity (at date of cracking of beams with 1% steel fiber were higher than the beams with 2% steel fiber by about (24%, (45% and (42% respectively

  4. The Behavior of Foundation Soil with and without Geosyntethic Reinforcement



    Full Text Available This paper presents the computed diagrams showing the soil behavior in two alternative calculation hypotheses (with/without geogrid reinforcement will be compared, so that the positive effect of two geogrid layers used for reinforcement is revealed. The diagrams show that the use of reinforcement layers contributes to a more uniform distribution of loads and to the decrease of the pressure, thus increasing the bearing capacity of the soil.

  5. Field Measurements and Pullout Tests of Reinforced Earth Retaining Wall

    陈群; 何昌荣; 朱分清


    In this paper, field measurements and pullout tests of a new type of reinforced earth retaining wall, which is reinforced by trapezoid concrete blocks connected by steel bar, are described. Field measurements included settlements of the earth fill, tensile forces in the ties and earth pressures on the facing panels during the construction and at completion. Based on the measurements, the following statements can be made: ( 1 ) the tensile forces in the ties increased with the height of backfill above the tie and there is a tensile force crest in most ties; (2) at completion, the measured earth pressures along the wall face were between the values of the active earth pressures and the pressures at rest; (3) larger settlements occurred near the face of the wall where a zone of drainage sand and gravel was not compacted properly and smaller settlements occurred in the well-compacted backfill. The results of field pullout tests indicated that the magnitudes of pullout resistances as well as tensile forces induced in the ties were strongly influenced by the relative displacements between the ties and the backfill, and pullout resistances increased with the height of backfill above the ties and the length of ties.

  6. Long-term behaviour of a 13 m high reinforced steep soil slope. Paper presented at Euro Geo 1 Maastrict

    Vaslestad, Jan; Fjeldheim, Nils; Braaten, Anne; Johansen, Tor Helge


    In the summer of 1993 a 13 m high reinforced soil slope was built in the City of Lillehammer as part of the new road system constructed in conncection with the 1994 winter olympic games. The reinforced soil slope with an inclination of 60 degrees and a vegetated front was selected as an alternative to a reinforced concrete wall. This proved to be a very cost effective solution. The reinforcement used was a woven polyester geotextile with a characteristic short time tensile strength of 150 kN/...

  7. Reinforcement of Epoxies Using Single Walled Carbon Nanotubes

    Krishnamoorti, Ramanan; Sharma, Jitendra; Chatterjee, Tirtha


    The reinforcement of bisphenol-A and bisphenol-F epoxies using single walled carbon nanotubes has been approached experimentally by understanding the nature of interactions between the matrices and nanotubes. Unassisted dispersions of single walled carbon nanotubes in epoxies were studied by a combination of radiation scattering (elastic small angle scattering and inelastic scattering), DSC based glass transition determination, melt rheology and solid-state mechanical testing in order to understand and correlate changes in local and global dynamics to the tailoring of composite mechanical properties. Significant changes in the glass transition temperature of the matrix can successfully account for changes in the viscoelastic properties of the epoxy dispersions for concentrations below the percolation threshold, while above the percolation threshold the network superstructure formed by the nanotubes controls the viscoelastic properties.

  8. Controllable theory and applications for the wall bolting reinforcement in the roadway of seam

    TAN Yun-liang; ZHANG Li-jun; XIAO Ya-xun


    By using the Radar penetrating technology and numerical simulations, the fractured zone could be easily determined. Both wall fractured zone and mining action of coal seam roadway were considered, and the bolt reinforcing criteria for wall including low limit condition and up limit condition were put up, which supply a basis for the bolt reinforcement design. For a particular engineering, there existed a bolt reinforcing controllable range which can be determined by the method put up in this paper. For the out of controllable range of bolt reinforcement in engineering, it is necessary to seek for other kind reinforcing technology, because the bolt reinforcing technology is not omnipotent.

  9. Parameter Sensitivity Analysis on Deformation of Composite Soil-Nailed Wall Using Artificial Neural Networks and Orthogonal Experiment

    Jianbin Hao


    Full Text Available Based on the back-propagation algorithm of artificial neural networks (ANNs, this paper establishes an intelligent model, which is used to predict the maximum lateral displacement of composite soil-nailed wall. Some parameters, such as soil cohesive strength, soil friction angle, prestress of anchor cable, soil-nail spacing, soil-nail diameter, soil-nail length, and other factors, are considered in the model. Combined with the in situ test data of composite soil-nail wall reinforcement engineering, the network is trained and the errors are analyzed. Thus it is demonstrated that the method is applicable and feasible in predicting lateral displacement of excavation retained by composite soil-nailed wall. Extended calculations are conducted by using the well-trained intelligent forecast model. Through application of orthogonal table test theory, 25 sets of tests are designed to analyze the sensitivity of factors affecting the maximum lateral displacement of composite soil-nailing wall. The results show that the sensitivity of factors affecting the maximum lateral displacement of composite soil nailing wall, in a descending order, are prestress of anchor cable, soil friction angle, soil cohesion strength, soil-nail spacing, soil-nail length, and soil-nail diameter. The results can provide important reference for the same reinforcement engineering.

  10. Soft impact testing of a wall-floor-wall reinforced concrete structure

    Vepsä, Ari, E-mail:; Calonius, Kim; Saarenheimo, Arja; Aatola, Seppo; Halonen, Matti


    Highlights: • A wall-floor-wall reinforced concrete structure was built. • The structure was subjected to three almost identical soft impact tests. • Response was measured with accelerometers, displacement sensors and strain gauges. • Modal tests was also carried out with the same structure in different conditions. • The results are meant to be used for validation of computational methods and models. - Abstract: Assessing the safety of the reactor building of a nuclear power plant against the crash of an airplane calls for valid computational tools such as finite element models and material constitutive models. Validation of such tools and models in turn calls for reliable and relevant experimental data. The problem is that such data is scarcely available. One of the aspects of such a crash is vibrations that are generated by the impact. These vibrations tend to propagate from the impact point to the internal parts of the building. If strong enough, these vibrations may cause malfunction of the safety-critical equipment inside the building. To enable validation of computational models for this type of behaviour, we have conducted a series of three tests with a wall-floor-wall reinforced concrete structure under soft impact loading. The response of the structure was measured with accelerometers, displacement sensors and strain gauges. In addition to impact tests, the structure was subjected to modal tests under different conditions. The tests yielded a wealth of useful data for validation of computational models and better understanding about shock induced vibration physics especially in reinforced concrete structures.

  11. Effect of discrete fibre reinforcement on soil tensile strength

    Jian Li


    Full Text Available The tensile behaviour of soil plays a significantly important role in various engineering applications. Compacted soils used in geotechnical constructions such as dams and clayey liners in waste containment facilities can suffer from cracking due to tensile failure. In order to increase soil tensile strength, discrete fibre reinforcement technique was proposed. An innovative tensile apparatus was developed to determine the tensile strength characteristics of fibre reinforced soil. The effects of fibre content, dry density and water content on the tensile strength were studied. The results indicate that the developed test apparatus was applicable in determining tensile strength of soils. Fibre inclusion can significantly increase soil tensile strength and soil tensile failure ductility. The tensile strength basically increases with increasing fibre content. As the fibre content increases from 0% to 0.2%, the tensile strength increases by 65.7%. The tensile strength of fibre reinforced soil increases with increasing dry density and decreases with decreasing water content. For instance, the tensile strength at a dry density of 1.7 Mg/m3 is 2.8 times higher than that at 1.4 Mg/m3. It decreases by 30% as the water content increases from 14.5% to 20.5%. Furthermore, it is observed that the tensile strength of fibre reinforced soil is dominated by fibre pull-out resistance, depending on the interfacial mechanical interaction between fibre surface and soil matrix.

  12. Effect of discrete fibre reinforcement on soil tensile strength

    Jian Li; Chaosheng Tang; Deying Wang; Xiangjun Pei; Bin Shi


    The tensile behaviour of soil plays a significantly important role in various engineering applications. Compacted soils used in geotechnical constructions such as dams and clayey liners in waste containment facilities can suffer from cracking due to tensile failure. In order to increase soil tensile strength, discrete fibre reinforcement technique was proposed. An innovative tensile apparatus was developed to deter-mine the tensile strength characteristics of fibre reinforced soil. The effects of fibre content, dry density and water content on the tensile strength were studied. The results indicate that the developed test apparatus was applicable in determining tensile strength of soils. Fibre inclusion can significantly in-crease soil tensile strength and soil tensile failure ductility. The tensile strength basically increases with increasing fibre content. As the fibre content increases from 0%to 0.2%, the tensile strength increases by 65.7%. The tensile strength of fibre reinforced soil increases with increasing dry density and decreases with decreasing water content. For instance, the tensile strength at a dry density of 1.7 Mg/m3 is 2.8 times higher than that at 1.4 Mg/m3. It decreases by 30% as the water content increases from 14.5% to 20.5%. Furthermore, it is observed that the tensile strength of fibre reinforced soil is dominated by fibre pull-out resistance, depending on the interfacial mechanical interaction between fibre surface and soil matrix.

  13. Mechanism of Geogrid Reinforced Soil at Bridge Approach

    FENG Guangle; LUO Rong; CHEN Congxin


    Using Geogrid-Reinforced Soil (GRS) we studied the working mechanism and design method of GRS at bridge approach with high backfill by field experiment. In a highway section where the height of backfill is 13.5 meters, geogrids were used at two bridge approaches to address the bumping problems. Some soil pressure cells were used to measure the normal and lateral soil pressure at different locations in the roadbed. The experimental results indicate that geogrids in geogrid-reinforced soil (GRS) could produce an uplift force, the closer the location to the abutment, the larger the uplift force, and the reduction of measured soil pressures compared with theoretical values was the largest at the bottom of roadbed, less at the top than at the bottom, and the least in the mid-height of roadbed than at the bottom. These findings are different from those of the traditional greogrid-reinforced subgrade design method.

  14. Effect of Horizontal Tied Rebars on Precast Reinforced Concrete Core Walls

    Nakachi, Tadaharu


    Multistory core walls installed in high-rise reinforced concrete buildings effectively reduce seismic vibration. On the other hand, precast core walls are considered effective for construction because they can be built more quickly than cast-in-place core walls. In this study, lateral loading tests were conducted on precast wall columns simulating the corner and the area near the corner of the L-shaped precast core wall. The specimen consisted of four square-section precast columns. The verti...

  15. Analytical Study on the Beyond Design Seismic Capacity of Reinforced Concrete Shear Walls

    Nugroho, Tino Sawaldi Adi [Korea Advanced Institute of Science and Technology, Daejeon (Korea, Republic of); Chi, Ho-Seok [Korea Institute of Nuclear Safety, Daejeon (Korea, Republic of)


    The OECD-NEA has organized an international benchmarking program to better understand this critical issue. The benchmark program provides test specimen geometry, test setup, material properties, loading conditions, recorded measures, and observations of the test specimens. The main objective of this research is to assess the beyond design seismic capacity of the reinforced concrete shear walls tested at the European Laboratory for Structural Assessment between 1997 and 1998 through participation in the OECD-NEA benchmark program. In this study, assessing the beyond design seismic capacity of reinforced concrete shear walls is performed analytically by comparing numerical results with experimental results. The seismic shear capacity of the reinforced concrete shear wall was predicted reasonably well using ABAQUS program. However, the proper calibration of the concrete material model was necessary for better prediction of the behavior of the reinforced concrete shear walls since the response was influenced significantly by the material constitutive model.

  16. Uplift of Symmetrical Anchor Plates by Using Grid-Fixed Reinforced Reinforcement in Cohesionless Soil

    Hamed Niroumand; Khairul Anuar Kassim


    Uplift response of symmetrical anchor plates with and without grid fixed reinforced (GFR) reinforcement was evaluated in model tests and numerical simulations by Plaxis. Many variations of reinforcement layers were used to reinforce the sandy soil over symmetrical anchor plates. In the current research, different factors such as relative density of sand, embedment ratios, and various GFR parameters including size, number of layers, and the proximity of the layer to the symmetrical anchor plate were investigated in a scale model. The failure mechanism and the associated rupture surface were observed and evaluated. GFR, a tied up system made of fiber reinforcement polymer (FRP) strips and end balls, was connected to the geosynthetic material and anchored into the soil. Test results showed that using GFR reinforcement significantly improved the uplift capacity of anchor plates. It was found that the inclusion of one layer of GFR, which rested directly on the top of the anchor plate, was more effective in enhancing the anchor capacity itself than other methods. It was found that by including GFR the uplift response was improved by 29%. Multi layers of GFR proved more effective in enhancing the uplift capacity than a single GFR reinforcement. This is due to the additional anchorage provided by the GFR at each level of reinforcement. In general, the results show that the uplift capacity of symmetrical anchor plates in loose and dense sand can be significantly increased by the inclusion of GFR. It was also observed that the inclusion of GFR reduced the requirement for a large L/D ratio to achieve the required uplift capacity. The laboratory and numerical analysis results are found to be in agreement in terms of breakout factor and failure mechanism pattern.

  17. Mechanical properties of tree roots for soil reinforcement models

    Cofie, P.


    Evidence from forestry has shown that part of the forest floor bearing capacity is delivered by tree roots. The beneficial effect however varies and diminishes with increasing number of vehicle passes. Roots potential for reinforcing the soil is known to depend among others on root mechanical proper

  18. Mechanical properties of tree roots for soil reinforcement models

    Cofie, P.


    Evidence from forestry has shown that part of the forest floor bearing capacity is delivered by tree roots. The beneficial effect however varies and diminishes with increasing number of vehicle passes. Roots potential for reinforcing the soil is known to depend among others on root

  19. Nanomodified compositions based on finely dispersed binders for soil reinforcement

    Alimov Lev


    Full Text Available Theoretical prerequisites on the possibility of improvement of physical and mechanical properties of soils at underground space development, their stability at different aggressive actions by means of their structure impregnation with nanomodified suspensions on the basis of especially finely dispersed mineral binders are developed. The features of influence of plasticizers on penetration ability and sedimentation stability of suspensions are revealed. Soil body reinforcement after its impregnation may achieve considerable values, which is related to the features of interaction of components of impregnating composition with extended surface of soil pore space.

  20. Experimental Investigation on Flexural Performance of Masonry Walls Reinforced with GFRP

    LIU Jifu; LIU Ming; SONG Yupu


    This paper presents the results of a test program for flexure reinforcing characteristics of gless fiber-rein forced polymer(GFRP) sheets bonded to masonry beams. A total of eight specimens subjected to monotonic four-point bending were tested up to failure. These specimens were constructed with two different bond patterns. Six of these specimens were reinforced by using GFRP sheets prior to testing, and the remaining two were not reinforced. The test results indicate a significant increase in both load-bearing capacity and ductile performance of the reinforced walls over the unreinforced ones.

  1. A new dedicated finite element for push-over analysis of reinforced concrete shear wall systems

    Delal Doğru ORMANCI


    Full Text Available In this study, a finite element which has been analyzed based on anisotropic behavior of reinforced shear walls is developed. Element stiffness matrices were varied based on whether the element is in the tension or the compression zone of the cross-section. Nonlinear behavior of reinforced shear wall model is investigated under horizontal loads. This behavior is defined with a similar approach to plastic hinge assumption in frame structures that the finite element behaves lineer elastic between joints and plastic deformations are concentrated on joints as vertical plastic displacements. According to this acceptance, plastic behavior of reinforced shear wall occurs when the vertical strain reaches elastic strain limit. In the definition of finite element, displacement functions are chosen considering that the partition of shear walls just at floor levels, are enough for solution. Results of this study are compared with the solution obtained from a different computer programme and experimental results.

  2. Design Method of Reinforced Concrete Shear Wall Using EBCS

    Dr. Suresh Borra


    Full Text Available Concrete shear walls or structural walls are often used in multistory buildings to resist lateral loads such as wind, seismic and blast loads. Such walls are used when the frame system alone is insufficient or uneconomical to withstand all the lateral loads or when partition walls can be made load bearing, replacing columns and beams. The analysis and design of buildings with shear walls became simple using commercially available computer programs based on the finite element method (FEM and subsequent implementation of stress integration techniques to arrive at generalized forces (axial, shear, and moments. On the other hand, design engineers without such facilities or those with computer facilities lacking such features use simple method of analysis and design by taking the entire dimensions of the walls. This is done by considering the shear walls as wide columns of high moment of inertia and following the same procedure as for columns. The primary purpose of this paper is believed that structural engineers working in the analysis and design of highrise buildings will be benefited from the design shear wall by using EBCS: 2-1995 and EBCS:8-1995codes and its results.

  3. Extended mesh repair with external oblique muscle reinforcement for abdominal wall contour abnormalities following TRAM flap.

    Israeli, Ron; Hazani, Ron; Feingold, Randall S; DeNoto, George; Scheiner, Marc S


    Many patients undergoing reconstructive surgery after mastectomy opt for reconstruction with the transverse rectus abdominis myocutaneous (TRAM) flap. Among the morbidities related to TRAM flap reconstruction is the development of abdominal wall contour abnormalities, including bulges or hernias. Several repair techniques at the flap abdominal wall donor site have been described for use at the time of flap harvest in an attempt to reduce the risk of such abdominal wall complications. For patients that develop abdominal wall contour abnormalities, numerous reconstructive options have been reported, with mixed results. Ten patients were identified as having abdominal wall contour abnormalities after a TRAM flap and underwent an extended mesh repair with external oblique muscle reinforcement. The mesh was secured to the bony landmarks of the lower abdomen and the abdominal wall fascia. All patients achieved complete resolution of abdominal wall bulging. In the follow-up period, no recurrences, infections, or seromas were noted. One patient, who failed an earlier repair at the inferior abdominal wall, reported symptoms consistent with a scar neuroma. Symptoms were treated successfully with gabapentin and a nonsteroidal anti-inflammatory drug. We propose a novel and reliable method of lower abdominal wall reconstruction for patients with post-TRAM flap abdominal wall contour abnormalities. This technique incorporates the use of a large Marlex mesh reinforced with bilateral external oblique muscle flaps. We report a series of 10 patients who have achieved resolution of their symptoms and have regained a natural, flat-appearing abdominal wall contour.

  4. The influence of self-compacting steel fibre reinforced concrete infill on the flexure strength and ductility of masonry walls

    Oliveira, Luiz António Pereira de; Bernardo, Luís Filipe Almeida


    This paper presents an experimental study on the influence of longitudinal reinforcement ratio and steel fibre volume in self-compacting concrete infill on the strength and ductility of reinforced masonry walls subjected to flexure. Flexure tests were performed as four-point bending tests on twelve walls. The analysis of the concrete infill contribution to the walls capacity is made considering recent recommendations for steel fibre reinforced concrete design. A ductility...

  5. Load-carrying capacity of lightly reinforced, prefabricated walls of lightweight aggregate concrete with open structure

    Goltermann, Per


    The paper presents and evaluates the results of a coordinated testing of prefabricated, lightly reinforced walls of lightweight aggregate concrete with open structure. The coordinated testing covers all wall productions in Denmark and will therefore provide a representative assessment of the qual...... of the quality actually produced. Existing and new formulas for the capacity are evaluated by comparison to the test results and a new model with a good correlation with the test results is presented....

  6. Steel Sheet Pile Walls in Soft Soil

    Kort, D.A.


    For almost a century, steel sheet pile walls are applied worldwide as earth retaining structures for excavations and quay walls. Within the framework of the development of European structural codes for Civil Engineering works, the Eurocodes, Eurocode 3 Part 5 for design of steel sheet pile walls was

  7. Is Regional Root Reinforcement Controlled by Soil Moisture Variability?

    Hales, T.; Ford, C. R.


    of "bound water" (water present in the cell wall), which in turn affected the strength of the cellulose fibrils that provide tensile strength. This phenomenon, which is the reason any wet wood is weaker than dry wood, results in a 50% difference in root tensile strength within the range of soil moisture measured in the field. We used a one-dimensional finite difference model to explore the effects of soil moisture on root cohesion. Our model shows that changes in the distribution of root biomass represent the primary control on root cohesion (representing up to 50% of intra-specific variability in root cohesion). Local changes in soil moisture result in ~20% change in the overall root cohesion. Our work suggest a feed-forward process in precipitation (and thus soil moisture), root strength changes, and debris flow hazard.

  8. Experimental studies on behavior of fully grouted reinforced-concrete masonry shear walls

    Zhao, Yan; Wang, Fenglai


    An experimental study is conducted on fully grouted reinforced masonry shear walls (RMSWs) made from concrete blocks with a new configuration. Ten RMSWs are tested under reversed cyclic lateral load to investigate the influence of different reinforcements and applied axial stress values on their seismic behavior. The results show that flexural strength increases with the applied axial stress, and shear strength dominated by diagonal cracking increases with both the amount of horizontal reinforcement and applied axial stress. Yield displacement, ductility, and energy dissipation capability can be improved substantially by increasing the amount of horizontal reinforcement. The critical parameters for the walls are derived from the experiment: displacement ductility values corresponding to 15% strength degradation of the walls reach up to 2.6 and 4.5 in the shear and flexure failure modes, respectively; stiffness values of flexure- and shear-dominated walls rapidly degrade to 17%-19% and 48%-57% of initial stiffness at 0.50 D max (displacement at peak load). The experiment suggests that RMSWs could be assigned a higher damping ratio (˜14%) for collapse prevention design and a lower damping value (˜7%) for a fully operational limit state or serviceability limit state.

  9. Clinical Application of a Silk Fibroin Protein Biologic Scaffold for Abdominal Wall Fascial Reinforcement

    Mark W. Clemens, MD


    Conclusions: Postoperative complication rates after 18 months were low, and most surgical complications were managed nonoperatively on an outpatient basis without mesh removal. To our knowledge, this is the only series to report on a long-lasting, transitory SBS for abdominal wall repair and reinforcement. Procedure-specific outcome studies are warranted to delineate optimal patient selection and define potential device characteristic advantages.


    张铭; 翁家杰


    The paper briefly describes the range and methods of the research on the stability of frozen wall. Using the Back Analysis Method combining with the model test of frozen wall, the comprchcnsire study on the stability of frozen wall is firstly carried out by the authors. Finally, a new viewpointof adopting limited strain as the major criteria of stability in frozen soil cngincertng is proposed.

  11. Plastic Fibre Reinforced Soil Blocks as a Sustainable Building Material

    Prasad, C. K. Subramania; Nambiar, E. K. Kunhanandan; Abraham, Benny Mathews


    Solid waste management, especially the huge quantity of waste plastics, is one of the major environmental concerns nowadays. Their employability in block making in the form of fibres, as one of the methods of waste management, can be investigated through a fundamental research. This paper highlights the salient observations from a systematic investigation on the effect of embedded fibre from plastic waste on the performance of stabilised mud blocks. Stabilisation of the soil was done by adding cement, lime and their combination. Plastic fibre in chopped form from carry bags and mineral water bottles were added (0.1% & 0.2% by weight of soil) as reinforcement. The blocks were tested for density, and compressive strength, and observed failure patterns were analysed. Blocks with 0.1% of plastic fibres showed an increase in strength of about 3 to 10%. From the observations of failure pattern it can be concluded that benefits of fibre reinforcement includes both improved ductility in comparison with raw blocks and inhibition of crack propogation after its initial formation.

  12. Structural performance of new thin-walled concrete sandwich panel system reinforced with bfrp shear connectors

    Hodicky, Kamil; Hulin, Thomas; Schmidt, Jacob Wittrup


    This paper presents a new thin-walled concrete sandwich panel system reinforced with basalt fiber-reinforced plastic (BFRP) with optimum structural performances and a high thermal resistance developed by Connovate and Technical University of Denmark. The shear connecting system made of a BFRP grid...... is described and provides information on the structural design with its advantages. Experimental and numerical investigations of the BFRP connecting systems were performed. The experimental program included testing of small scale specimens by applying shear (push-off) loading and semi-full scale specimens...

  13. Reinforced Thermoplastic Polyimide with Dispersed Functionalized Single Wall Carbon Nanotubes

    Lebron-Colon, Marisabel; Meador, Michael A.; Gaier, James R.; Sola, Francisco; Scheiman, Daniel A.; McCorkle, Linda S.


    Molecular pi-complexes were formed from pristine HiPCO single-wall carbon nanotubes (SWCNTs) and 1-pyrene- N-(4- N'-(5-norbornene-2,3-dicarboxyimido)phenyl butanamide, 1. Polyimide films were prepared with these complexes as well as uncomplexed SWCNTs and the effects of nanoadditive addition on mechanical, thermal, and electrical properties of these films were evaluated. Although these properties were enhanced by both nanoadditives, larger increases in tensile strength and thermal and electrical conductivities were obtained when the SWCNT/1 complexes were used. At a loading level of 5.5 wt %, the Tg of the polyimide increased from 169 to 197 C and the storage modulus increased 20-fold (from 142 to 3045 MPa). The addition of 3.5 wt % SWCNT/1 complexes increased the tensile strength of the polyimide from 61.4 to 129 MPa; higher loading levels led to embrittlement and lower tensile strengths. The electrical conductivities (DC surface) of the polyimides increased to 1 x 10(exp -4) Scm(exp -1) (SWCNT/1 complexes loading level of 9 wt %). Details of the preparation of these complexes and their effects on polyimide film properties are discussed.

  14. Soil moisture causes dynamic adjustments to root reinforcement that reduce slope stability

    Tristram C. Hales; Chelcy F. Miniat


    In steep soil-mantled landscapes, the initiation of shallow landslides is strongly controlled by the distribution of vegetation, whose roots reinforce the soil. The magnitude of root reinforcement depends on the number, diameter distribution, orientation and the mechanical properties of roots that cross potential failure planes. Understanding how these...

  15. Application of Bond-Slip in the Finite Element Analyses of Reinforced Concrete Shear Walls

    İlker Kazaz


    Full Text Available Transfer of tensile forces from reinforcing steel into the surrounding concrete affects the behavior of reinforced concrete members. This transfer relies on the bond action between the steel and the concrete. Under monotonic loading the part of bond strength due to chemical adhesion is easily exhausted and bearing against the lugs is the primary load-transfer mechanism at loads near the ultimate. These stresses cause internal cracking of concrete at the steel-concrete interface. This paper deals with the finite element modeling of the bond-slip and its application due to internal cracking of the first layer of concrete surrounding the bar and the bending and/ or cracking of the small concrete teeth near the bar lugs. A previously proposed constitutive steel stress-bond slip relation by Mirza and Houde (1979 was used in finite element analysis of reinforced concrete shear wall specimens and the results were presented.

  16. Synthesis and Characterization of Multi Wall Carbon Nanotubes (MWCNT) Reinforced Sintered Magnesium Matrix Composites

    Vijaya Bhaskar, S.; Rajmohan, T.; Palanikumar, K.; Bharath Ganesh Kumar, B.


    Metal matrix composites (MMCs) reinforced with ceramic nano particles (less than 100 nm), termed as metal matrix nano composites (MMNCs), can overcome those disadvantages associated with the conventional MMCs. MMCs containing carbon nanotubes are being developed and projected for diverse applications in various fields of engineering like automotive, avionic, electronic and bio-medical sectors. The present investigation deals with the synthesis and characterization of hybrid magnesium matrix reinforced with various different wt% (0-0.45) of multi wall carbon nano tubes (MWCNT) and micro SiC particles prepared through powder metallurgy route. Microstructure and mechanical properties such as micro hardness and density of the composites were examined. Microstructure of MMNCs have been investigated by scanning electron microscope, X-ray diffraction and energy dispersive X-ray spectroscopy (EDS) for better observation of dispersion of reinforcement. The results indicated that the increase in wt% of MWCNT improves the mechanical properties of the composite.

  17. Calibration of a hysteretic model for glass fiber reinforced gypsum wall panels

    Janardhana, Maganti; Robin Davis, P.; Ravichandran, S. S.; Prasad, A. M.; Menon, D.


    Glass fiber reinforced gypsum (GFRG) wall panels are prefabricated panels with hollow cores, originally developed in Australia and subsequently adopted by India and China for use in buildings. This paper discusses identification and calibration of a suitable hysteretic model for GFRG wall panels filled with reinforced concrete. As considerable pinching was observed in the experimental results, a suitable hysteretic model with pinched hysteretic rule is used to conduct a series of quasi-static as inelastic hysteretic response analyses of GFRG panels with two different widths. The calibration of the pinching model parameters was carried out to approximately match the simulated and experimental responses up to 80% of the peak load in the post peak region. Interestingly, the same values of various parameters (energy dissipation and pinching related parameters) were obtained for all five test specimens.

  18. Post-cracking behavior of blocks, prisms, and small concrete walls reinforced with plant fiber

    I. I. Soto

    Full Text Available Structural masonry using concrete blocks promotes the rationalization of construction projects, lowering the final cost of a building through the elimination of forms and the reduction of the consumption of reinforcement bars. Moreover, production of a block containing a combination of concrete and vegetable fiber sisal results in a unit with properties such as mechanical strength, stiffness, flexibility, ability to absorb energy, and post-cracking behavior that are comparable to those of a block produced with plain concrete. Herein are reported the results of a study on the post-cracking behavior of blocks, prisms, and small walls reinforced with sisal fibers (lengths of 20 mm and 40 mm added at volume fractions of 0.5% and 1%. Tests were performed to characterize the fibers and blocks and to determine the compressive strength of the units, prisms, and small walls. The deformation modulus of the elements was calculated and the stress-strain curves were plotted to gain a better understanding of the values obtained. The compression test results for the small walls reinforced with fibers were similar to those of the reference walls and better than the blocks and prisms with added fibers, which had resistances lower than those of the corresponding conventional materials. All elements prepared with the addition of sisal exhibited an increase in the deformation capacity (conferred by the fibers, which was observed in the stress-strain curves. The failure mode of the reference elements was characterized by an abrupt fracture, whereas the reinforced elements underwent ductile breakage. This result was because of the presence of the fibers, which remained attached to the faces of the cracks via adhesion to the cement matrix, thus preventing loss of continuity in the material. Therefore, the cement/plant fiber composites are advantageous in terms of their ductility and ability to resist further damage after cracking.

  19. Experimental Study of Cement Mortar-Steel Fiber Reinforced Rammed Earth Wall

    Shuai Yang


    Full Text Available Rammed earth construction is an ancient technique which has recently attracted renewed interest throughout the world. Although rammed earth is currently regarded as a promising material in the construction industry in the context of sustainable development, it is difficult to quantify its bearing capacity, mechanical performance, as well as retrofitting approach, which discourages people from large-scale application in architectural engineering. This paper is devoted to the study of these problems based on rammed earth wall model experimentation. Three different models are studied considering different material components as well as structural configurations. By measuring the strain and deformation of the rammed earth wall models subjected to uniformly-distributed vertical loading, their ultimate bearing capacities are tested based on experimental investigation. Then the method of cement mortar-steel fiber reinforcement (CMSF is carried out to study the ultimate bearing capacity enhancement of the wall models. Results show that the method of cement mortar-steel fiber reinforcement can increase the ultimate bearing capacity of the rammed earth wall models significantly, which is of relevant engineering significance in practical application.

  20. In Plan Shear Retrofit of Masonry Walls with Fibre Reinforced Polymer Composites Experimental Investigations

    Tamás Nagy-György


    Full Text Available The paper presents the results from tests on clay brick masonry walls strengthened using fiber reinforced polymer (FRP composites. Five 1.50x1.50 m wall specimens have been subjected to pure in plan shear loads up to failure and then retrofitted on one side, with different types, percentages and lay-ups of the fiber sheets. Based on the experi¬mental results, it was proven the effectiveness of using externally bonded composites for retrofitting brick masonry walls, with less disruption during strengthening, and in this way with reduced costs compared with other conventional repairing and strengthening tech¬niques. Performances of the different strengthening configurations were compared in terms of ultimate load, strain in composite and failure mechanism.

  1. Shear Strength of Unreinforced Masonry Wall Retrofitted with Fiber Reinforced Polymer and Hybrid Sheet

    Yun-Cheul Choi


    Full Text Available Unreinforced masonry (URM structures represent a significant portion of existing historical structures around the world. Recent earthquakes have shown the need for seismic retrofitting for URM structures. Various types of strengthening methods have been used for URM structures. In particular, a strengthening technique using externally bonded (EB fiber reinforced polymer (FRP composites has attracted engineers since EB FRP materials effectively enhance the shear strength of URM walls with negligible change to cross-sectional area and weight of the walls. Research has been extensively conducted to determine characteristics of URM walls strengthened with EB FRP materials. However, it is still difficult to determine an appropriate retrofitting level due to the complexity of mechanical behavior of strengthened URM walls. In this study, in-plane behavior under lateral loading was, therefore, investigated on a full-scale nonstrengthened URM wall and URM walls retrofitted with two different FRP materials: carbon (CFRP and hybrid (HFRP sheets. The test results indicated that both FRP composites were effective in increasing shear strength in comparison with the control specimen. However, better performance was obtained with HFRP compared to CFRP. In addition, an equation for estimating effective strain was proposed, and the theoretical results were in good agreement with the experimental ones.

  2. Progressive collapse resisting capacity of reinforced concrete load bearing wall structures

    Alireza Rahai; Alireza Shahin; Farzad Hatami


    Reinforced concrete (RC) load bearing wall is widely used in high-rise and mid-rise buildings. Due to the number of walls in plan and reduction in lateral force portion, this system is not only stronger against earthquakes, but also more economical. The effect of progressive collapse caused by removal of load bearing elements, in various positions in plan and stories of the RC load bearing wall system was evaluated by nonlinear dynamic and static analyses. For this purpose, three-dimensional model of 10-story structure was selected. The analysis results indicated stability, strength and stiffness of the RC load-bearing wall system against progressive collapse. It was observed that the most critical condition for removal of load bearing walls was the instantaneous removal of the surrounding walls located at the corners of the building where the sections of the load bearing elements were changed. In this case, the maximum vertical displacement was limited to 6.3 mm and the structure failed after applying the load of 10 times the axial load bored by removed elements. Comparison between the results of the nonlinear dynamic and static analyses demonstrated that the “load factor” parameter was a reasonable criterion to evaluate the progressive collapse potential of the structure.

  3. Simulation of reinforced concrete short shear wall subjected to cyclic loading

    Parulekar, Y.M., E-mail: [Bhabha Atomic Research Centre (India); Reddy, G.R., E-mail: [Bhabha Atomic Research Centre (India); Vaze, K.K. [Reactor Design and Development Group, Bhabha Atomic Research Centre (India); Pegon, P. [Joint Research Centre, Ispra (Italy); Wenzel, H. [Vienna Consulting Engineers, Vienna (Austria)


    Highlights: • Prediction of the capacity of squat shear wall using tests and analysis. • Modification of model of concrete in the softening part. • Pushover analysis using softened truss theory and FE analysis is performed. • Modified concrete model gives reasonable accurate peak load and displacement. • The ductility, ultimate load and also crack pattern can be accurately predicted. - Abstract: This paper addresses the strength and deformation capacity of stiff squat shear wall subjected to monotonic and pseudo-static cyclic loading using experiments and analysis. Reinforced concrete squat shear walls offer great potential for lateral load resistance and the failure mode of these shear walls is brittle shear mode. Shear strength of these shear walls depend strongly on softening of concrete struts in principal compression direction due to principal tension in other direction. In this work simulation of the behavior of a squat shear wall is accurately predicted by finite element modeling by incorporating the appropriate softening model in the program. Modification of model of concrete in the softening part is suggested and reduction factor given by Vecchio et al. (1994) is used in the model. The accuracy of modeling is confirmed by comparing the simulated response with experimental one. The crack pattern generated from the 3D model is compared with that obtained from experiments. The load deflection for monotonic loads is also obtained using softened truss theory and compared with experimental one.

  4. Effect of the selected seismic energy dissipation capacity on the materials quantity for reinforced concrete walls

    José Miguel Benjumea Royero


    Full Text Available Context: Regarding their design of reinforced concrete structural walls, the Colombian seismic design building code allows the engineer to select one of the three seismic energy dissipation capacity (ordinary, moderate, and special depending on the seismic hazard of the site. Despite this, it is a common practice to choose the minor requirement for the site because it is thought that selecting a higher requirement will lead to larger structural materials amounts and, therefore, cost increments.  Method: In this work, an analytical study was performed in order to determine the effect of the selected energy dissipation capacity on the quantity of materials and ductility displacement capacity of R/C walls. The study was done for a region with low seismic hazard, mainly because this permitted to explore and compare the use of the three seismic energy dissipations capacities. The effect of different parameters such as the wall total height and thickness, the tributary loaded area, and the minimum volumetric steel ratio were studied. Results: The total amount of steel required for the walls with moderate and special energy dissipation capacity corresponds, on average, to 77% and 89%, respectively, of the quantity required for walls with minimum capacity. Conclusions: it is possible to achieve reductions in the total steel required weight when adopting either moderated or special seismic energy dissipation instead of the minimum capacity.  Additionally, a significant increment in the seismic ductility displacements capacity of the wall was obtained.

  5. Pile-soil stress ratio in bidirectionally reinforced composite ground by considering soil arching effect

    邹新军; 杨眉; 赵明华; 杨小礼


    To discuss the soil arching effect on the load transferring model and sharing ratios by the piles and inter-pile subsoil in the bidirectionally reinforced composite ground, the forming mechanism, mechanical behavior and its effect factors were discussed in detail. Then, the unified strength theory was introduced to set up the elastoplastic equilibrium differential equation of the subsoil under the limit equilibrium state. And from the equation, the solutions were derived with the corresponding formulas presented to calculate the earth pressure over and beneath the horizontal reinforced cushion or pillow, the stress of inter-pile subsoil and the pile-soil stress ratio. Based on the obtained solutions and measured data from an engineering project, the influence rules by the soil property parameters (i.e., the cohesion c and internal friction angle φ) and pile spacing on the pile-soil stress ratio n were discussed respectively. The results show that to improve the load sharing ratio by the piles, the more effective means for filling materials with a larger value of φ is to increase the ratio of pile cap size to spacing, while to reduce the pile spacing properly and increase the value of cohesion c is advisable for those filling materials with a smaller value of φ.


    Timothy Garfield; William D. Richins; Thomas K. Larson; Chris P. Pantelides; James E. Blakeley


    The structural integrity of reinforced concrete structures in blast events is important for critical facilities. This paper presents experimental data generated for calibrating detailed finite element models that predict the performance of reinforced concrete wall panels with a wide range of construction details under blast loading. The test specimens were 1.2 m square wall panels constructed using Normal Weight Concrete (NWC) or Fiber Reinforced Concrete (FRC). FRC consists of macro-synthetic fibers dispersed in NWC. Five types of panels were tested: NWC panels with steel bar reinforcement (Type A); FRC panels without additional reinforcement (Type B); FRC panels with steel bar reinforcement (Type C); NWC panels with glass fiber reinforced polymer (GFRP) bar reinforcement (Type D); and NWC panels reinforced with steel bar reinforcement and external bidirectional GFRP overlays on both faces (Type E). An additional three Type C panels were used as control specimens (CON). Each panel type was constructed with three thicknesses: 152 mm, 254 mm, and 356 mm. The panels were instrumented with strain gauges, and accelerometers; in addition, pressure sensors and high speed videos were employed during the blast events. Panel types C and E had the best performance, whereas panel type B did not perform well. Preliminary dynamic simulations show crack patterns similar to the experimental results.

  7. Piecewise Function Hysteretic Model for Cold-Formed Steel Shear Walls with Reinforced End Studs

    Jihong Ye


    Full Text Available Cold-formed steel (CFS shear walls with concrete-filled rectangular steel tube (CFRST columns as end studs can upgrade the performance of mid-rise CFS structures, such as the vertical bearing capacity, anti-overturning ability, shear strength, and fire resistance properties, thereby enhancing the safety of structures. A theoretical hysteretic model is established according to a previous experimental study. This model is described in a simple mathematical form and takes nonlinearity, pinching, strength, and stiffness deterioration into consideration. It was established in two steps: (1 a discrete coordinate method was proposed to determine the load-displacement skeleton curve of the wall, by which governing deformations and their corresponding loads of the hysteretic loops under different loading cases can be obtained; afterwards; (2 a piecewise function was adopted to capture the hysteretic loop relative to each governing deformation, the hysteretic model of the wall was further established, and additional criteria for the dominant parameters of the model were stated. Finally, the hysteretic model was validated by experimental results from other studies. The results show that elastic lateral stiffness Ke and shear capacity Fp are key factors determining the load-displacement skeleton curve of the wall; hysteretic characteristics of the wall with reinforced end studs can be fully reflected by piecewise function hysteretic model, moreover, the model has intuitional expressions with clear physical interpretations for each parameter, paving the way for predicting the nonlinear dynamic responses of mid-rise CFS structures.

  8. Improved design of special boundary elements for T-shaped reinforced concrete walls

    Ji, Xiaodong; Liu, Dan; Qian, Jiaru


    This study examines the design provisions of the Chinese GB 50011-2010 code for seismic design of buildings for the special boundary elements of T-shaped reinforced concrete walls and proposes an improved design method. Comparison of the design provisions of the GB 50011-2010 code and those of the American code ACI 318-14 indicates a possible deficiency in the T-shaped wall design provisions in GB 50011-2010. A case study of a typical T-shaped wall designed in accordance with GB 50011-2010 also indicates the insufficient extent of the boundary element at the non-flange end and overly conservative design of the flange end boundary element. Improved designs for special boundary elements of T-shaped walls are developed using a displacement-based method. The proposed design formulas produce a longer boundary element at the non-flange end and a shorter boundary element at the flange end, relative to those of the GB 50011-2010 provisions. Extensive numerical analysis indicates that T-shaped walls designed using the proposed formulas develop inelastic drift of 0.01 for both cases of the flange in compression and in tension.

  9. Reinforcement of thin-walled root canal structures for placement of esthetic dowels: a clinical report.

    Ayad, Mohamed F; Bahannan, Salma A; Rosenstiel, Stephen F


    Thin-walled root canals always present a challenge to dentists to select a restorative treatment that does not further weaken the thin tooth structure. The prognosis of dowel and core restorations can be unpredictable. This clinical report describes the treatment of a patient with extensive caries extending into the root canal of an endodontically treated maxillary central incisor. The use of a flowable composite resin in combination with a quartz fiber reinforced post is described, resulting in the rehabilitation of a structurally compromised root canal with satisfactory esthetic and functional outcomes.

  10. Design and fabrication of multi-walled hollow nanofibers by triaxial electrospinning as reinforcing agents in nanocomposites


    Multi-walled triaxial hollow fibers with two different outer wall materials are fabricated by core-sheath electrospinning process and integrated into epoxy matrix with or without primary glass fiber reinforcement to produce composites with enhanced mechanical properties. The morphologies of multi-walled hollow fibers are tailored by controlling the materials and processing parameters such as polymer and solvent types. The triaxial hollow fiber fabrication is achieved through using a nozzle co...

  11. 加筋土挡墙变形及筋材受力特征数值试验研究%Numerical experiment studies on deformation and geo-grid force of reinforced earth retaining wall



    Reinforced soil retaining wall is a kind of effective to solve the problem of high fill embankment and slope measures.In this paper, combined with a highway reinforced soil retaining wall project as the research background, with the aid of numerical analysis method and the deformation characteristics of the retaining wal and data col ected in-situ reinforcement material mechanical properties are studied, the analysis results show that the lower part of the retaining wall reinforcement material earth pressure value is the upper reinforcement material location, soil pressure maximum position from the retaining wal (0.3~0.4) H location;Reinforced materials on the tensile stress distribution and the size of the reinforcement materials stress, along the direction of reinforcement material in 0~1m within the scope of the approximate uniform distribution, exponential distribution outside the 1.0m;Maximum tensile strain values near the wall, along the reinforcement length direction tensile strain nonlinear decreasing; Reinforced retaining wall horizontal deformation along the depth are "fat bel y" shape distribution, the maximum horizontal deformation occurred to about one-third of the wall height, the size is about 16.5mm. Wall had a greater influence on the load on retaining wal and soil deformation;suggest the wal load take 30kpa as load limit of reinforced soil retaining wall. Research results can provide reference for design and construction of reinforced soil retaining wall structure.%加筋土挡墙是一种解决高填方路堤及边坡等问题的有效措施。本文结合某公路加筋土挡墙工程为研究背景,借助数值分析方法和现场实测数据对加筋土挡墙变形特性及筋材受力特性进行了研究。分析结果表明:挡墙下部筋材位置土压力值较上层筋材位置大,土压力最大值位置在距挡墙(0.3~0.4)倍的墙高位置处;筋材上的拉应力分布与筋材受力大小有关,沿筋材方向在0

  12. The electrostatic properties of Fiber-Reinforced-Plastics double wall underground storage gasoline tanks

    Li, Yipeng; Liu, Quanzhen; Meng, He; Sun, Lifu; Zhang, Yunpeng


    At present Fiber Reinforced Plastics (FRP) double wall underground storage gasoline tanks are wildly used. An FRP product with a resistance of more than 1011 Ω is a static non-conductor, so it is difficult for the static electricity in the FRP product to decay into the earth. In this paper an experimental system was built to simulate an automobile gasoline filling station. Some electrostatic parameters of the gasoline, including volume charge density, were tested when gasoline was unloaded into a FRP double wall underground storage tank. Measurements were taken to make sure the volume charge density in the oil-outlet was similar to the volume charge density in the tank. In most cases the volume charge density of the gasoline was more than 22.7 μC m-3, which is likely to cause electrostatic discharge in FRP double wall underground storage gasoline tanks. On the other hand, it would be hard to ignite the vapor by electrostatic discharge since the vapor pressure in the tanks is over the explosion limit. But when the tank is repaired or re-used, the operators must pay attention to the static electricity and some measurements should be taken to avoid electrostatic accident. Besides the relaxation time of charge in the FRP double wall gasoline storage tanks should be longer.

  13. Non-linear homogenized and heterogeneous FE models for FRCM reinforced masonry walls in diagonal compression

    Bertolesi, Elisa; Milani, Gabriele; Poggi, Carlo


    Two FE modeling techniques are presented and critically discussed for the non-linear analysis of tuff masonry panels reinforced with FRCM and subjected to standard diagonal compression tests. The specimens, tested at the University of Naples (Italy), are unreinforced and FRCM retrofitted walls. The extensive characterization of the constituent materials allowed adopting here very sophisticated numerical modeling techniques. In particular, here the results obtained by means of a micro-modeling strategy and homogenization approach are compared. The first modeling technique is a tridimensional heterogeneous micro-modeling where constituent materials (bricks, joints, reinforcing mortar and reinforcing grid) are modeled separately. The second approach is based on a two-step homogenization procedure, previously developed by the authors, where the elementary cell is discretized by means of three-noded plane stress elements and non-linear interfaces. The non-linear structural analyses are performed replacing the homogenized orthotropic continuum with a rigid element and non-linear spring assemblage (RBSM). All the simulations here presented are performed using the commercial software Abaqus. Pros and cons of the two approaches are herein discussed with reference to their reliability in reproducing global force-displacement curves and crack patterns, as well as to the rather different computational effort required by the two strategies.

  14. Demolition technique of high thin-wall hyperbolic reinforced concrete cool tower by directional controlled blasting

    Luo Yong; Cui Xiaorong; Lu Hua


    Based on blasting demolition of high thin-wall hyperbolic reinforced concrete cool tower,by virtue of engi-neering practice of blasting the tube concrete structures,the analysis and research were made on the mechanism of cool tower collapse through selecting blasting parameters and selecting gap form,gap size and gap angle.The cool tower was twisted,collapsed directionally and broken weU according to the design requirements.The expected results and purpo-ses of blasting were obtained with no back blow,total blasted pile approximates to 4 ~ 5 m,no occurrence of flying stones and no damage to fixed buildings and equipment,the large-sized hyperbolic thin-wall reinforced concrete cool towers are twisted during blasting and it collapses well with good breaking.The test and measurement of blasting vibra-ting velocity was carried out during blasting and the measuring results are much less than critical values specified by Safety Regulations for Blasting.The study shows that gap form,gap size and gap angle are the key factors to cool tower collapse and will give beneficial references to related theoretical study and field application.

  15. Experimental Study on Unconfined Compressive Strength of Basalt Fiber Reinforced Clay Soil

    Lei Gao


    Full Text Available In order to study the mechanism and effect of basalt fiber reinforced clay soil, a series of unconfined compressive strength tests conducted on clay soil reinforced with basalt fiber have been performed under the condition of optimum water content and maximum dry density. Both the content and length of basalt fiber are considered in this paper. When the effect of content is studied, the 12 mm long fibers are dispersed into clay soil at different contents of 0.05%, 0.1%, 0.15%, 0.20%, 0.25%, 0.30%, and 0.35%. When the effect of length is researched, different lengths of basalt fibers with 4 mm, 8 mm, 12 mm, and 15 mm are put into soil at the same content of 0.05%. Experimental results show that basalt fiber can effectively improve the UCS of clay soil. And the best content and length are 0.25% and 12 mm, respectively. The results also show that the basalt fiber reinforced clay soil has the “poststrong” characteristic. About the reinforcement mechanism, the fiber and soil column-net model is proposed in this paper. Based on this model and SEM images, the effect of fiber content and length is related to the change of fiber-soil column and formation of effective fiber-soil net.

  16. Examination of the behavior of gravity quay wall against liquefaction under the effect of wall width and soil improvement.

    Firoozi, Ali Akbar; Taha, Mohd Raihan; Mir Moammad Hosseini, S M; Firoozi, Ali Asghar


    Deformation of quay walls is one of the main sources of damage to port facility while liquefaction of backfill and base soil of the wall are the main reasons for failures of quay walls. During earthquakes, the most susceptible materials for liquefaction in seashore regions are loose saturated sand. In this study, effects of enhancing the wall width and the soil improvement on the behavior of gravity quay walls are examined in order to obtain the optimum improved region. The FLAC 2D software was used for analyzing and modeling progressed models of soil and loading under difference conditions. Also, the behavior of liquefiable soil is simulated by the use of "Finn" constitutive model in the analysis models. The "Finn" constitutive model is especially created to determine liquefaction phenomena and excess pore pressure generation.


    Ma, Jing

    Single Walled carbon nanotubes (SWNTs) possess superior mechanical, thermal and electrical properties. The use of SWNTs as a reinforcement in polymer matrix is a hot research topic. However, the poor dispersion of SWNTs in polymers and the weak interface between the nanotubes and polymers are two...... the chemical compatibility between polymer and SWNTs, and correlate the parameters with the dispersion of SWNTs and interfacial properties between SWNTs and polymers. Several different surface modifications on carbon nanotubes and different polymers are considered. The dispersion of SWNTs in solvents...... is evaluated by Dynamic Light scattering (DLS). The functional groups attached to SWNTs and degree of functionalization, and also the size of the nanotubes affect the HSP of the SWNTs. The extent by which functionalization take place is affected by the amount of defects on the nanotube surface. The strain...

  18. 软土地基上加筋土挡墙变形特征的有限元分析%FEM analysis of deformation characteristics of reinforced retaining walls on soft foundation

    王潇宇; 徐超; 吴迪


    Generally, the impact of foundation deformation has been not taken into account in the design of the reinforced retaining walls. However, tremendous deformation of the soft foundation may cause their failure. Based on the practice of a reinforced retaining wall, a model for the reinforced retaining wall on the soft foundation is established by means of numerical modeling method. The impact of differential deformation of the soft foundation on the reinforced retaining wall is analyzed. The results show that: (1) the eccentric action of the base pressure of the reinforced retaining wall will lead to the differential settlement of the soft foundation, and thus it results in adverse impact on the wall deformation and the failure of the free face; (2) the deformation of the face of the reinforced retaining wall is mainly caused by the differential settlement of the soft foundation; (3) the settlement curve of the foundation with the reinforced retaining wall is nearly linear, and the largest settlement point is under the face. The parametric analysis also indicates that the Young's modulus and face angle of the foundation soils and the characteristics of the backfill also have great impact on the deformation characteristics of the reinforced retaining wall.%针对在加筋土挡墙设计中,一般不考虑地基变形影响,而软土地基过大变形会造成加筋土挡墙失效的问题,结合某加筋土挡墙实例,利用数值模拟方法建立了软土地基上加筋土挡墙数值模型,分析了软土地基不均匀变形对加筋土挡墙的影响.结果表明:由于加筋土挡墙基底压力的偏心作用,会引起软土地基的差异沉降,对墙体侧向变形及向临空面倾覆有不利影响;加筋土挡墙面板变形主要是由地基不均匀沉降引起的;加筋土挡墙地基的沉降曲线近似线性,面板下地基沉降量最大.参数分析还揭示,地基土的杨氏模量和面板仰角、回填土特性等对加筋土挡墙变形特征均存在较大影响.

  19. Use of response envelopes for seismic margin assessment of reinforced concrete walls and slabs

    Ile, Nicolas; Frau, Alberto, E-mail:


    Highlights: • Proposal of a method for application of the elliptical envelope to RC shell elements. • Proposal of new algorithms for the seismic margin evaluation for RC shell elements. • Verification of a RC wall 3D structure, using the proposed assessment approach. - Abstract: Seismic safety evaluations of existing nuclear facilities are usually based on the assumption of structural linearity. For the design basis earthquake (DBE), it is reasonable to apply a conventional evaluation of the seismic safety of building structures and carry out a linear elastic analysis to assess the load effects on structural elements. Estimating the seismic capacity of a structural element requires an estimation of the critical combination of responses acting in this structural element and compare this combination with the capacity of the element. By exploiting the response-spectrum-based procedure for predicting the response envelopes in linear structures formulated by Menun and Der Kiureghian (2000a), algorithms are developed for the seismic margin assessment of reinforced concrete shell finite elements. These algorithms facilitate the comparison of the response-spectrum-based envelopes to prescribed capacity surfaces for the purpose of assessing the safety margin of this kind of structures. The practical application of elliptical response envelopes in case of shell finite elements is based on the use of layer models such as those developed by Marti (1990), which transfer the generalized stress field to three layers under the assumption that the two outer layers carry membrane forces and the internal layer carries only the out-of-plane shears. The utility of the assessment approach is discussed with reference to a case study of a 3D structure made of reinforced concrete walls.

  20. Investigation of Crack Resistance in Single Walled Carbon Nanotube Reinforced Polymer Composites Based on FEM

    Hosein Hemmatian


    Full Text Available Carbon nanotube (CNT is considered as a new generation of material possessing superior mechanical, thermal and electrical properties. The applications of CNT, especially in composite materials, i.e. carbon nanotube reinforced polymer have received great attention and interest in recent years. To characterize the influence of CNT on the stress intensity factor of nanocomposites, three fracture modes (opening, shearing and tearing are considered. The stress intensity factor of nanocomposites is evaluated using a representative volume element (RVE based on the continuum mechanics and finite element method (FEM. Inter-atomic interactions of CNT are simulated by beam elements in the finite element (FE model. Non-linear springbased line elements are employed to simulate the van der Waals (vdW bonds. In all fracture modes, the stress intensity factor was determined for pure matrix and matrix reinforced with single-walled carbon nanotube (SWCNT. Numerical results indicate that the load carrying capacities of the CNTs in a matrix are evident. Addition of CNTs in a matrix can increase the stiffness of the composite. Finally, the results showed that utilizing of SWCNT decreased the stress intensity factor and improved crack resistance.

  1. 加筋土挡土墙结构的应用%Application of Reinforced Earth Retaining Wall Structure

    黄国伟; 方鸿琪


    After 30 years of research and development the reinforced earth, invented by French Henri Vidal, is now widely used in the field of civil engineering. Researches and projects conducted by Reinforced Earth Group in the respect of reinforced earth are presented herein. The projects involve retaining wall for high speed highway, abutment, railway embankment, river weir, flood protection dike and retaining walls for industrial and military purposes. More than ten thousand sturdy and durable retaining walls of reinforced earth are built around the world.%法国人亨利·维特(Henri Vidal) 发明的加筋土经过30年的研究和发展,现已广泛用于土木工程领域。本文介绍了Reinforced Earth集团在加筋土方面的研究及项目情况,其项目领域涉及高速公路挡土墙、桥台、铁路路堤、河堤、水坝、防洪堤、工业及军事用途挡土墙等。在世界各地建造了1万多幅坚固耐用的加筋土墙。

  2. Performance of Geosynthetic-Reinforced Soils Under Static and Cyclic Loading

    M. Touahmia


    Full Text Available This paper investigates and discusses the composite behavior of geosynthetic reinforced soil mass. It presents the results of a series of large-scale laboratory tests supported by analytical methods to examine the performance of geogrid reinforcement subjected to static and cyclic pullout loading. The testing equipment and procedures used for this investigation are outlined. The results show that geosynthetic reinforcement can mobilize great resistance to static pulling load under high confining pressures. The reinforcement exhibits gradual deformation under cyclic loading showing no sign of imminent pullout failure for all levels of applied loads. In general, the results demonstrate that geosynthetic can be used in situations where loads are non-static, although care will be required in ensuring that appropriate factors of safety are applied to control the resulting deformation. A simplified analytical model for calculating the pulling capacity of geosynthetic reinforcement is proposed.

  3. Research on Liquid Stabilizer Reinforced Soil%液体固化剂加固土的研究

    彭波; 李文瑛; 戴经梁


    Based on systematic test research on liquid stabilizer, the mec hanism of reiforced soil is analyzed by using double electric layer theory, the road performance of liquid reinforced soil stabilizer reinforced soil and lime reinforced soil are compared.The results indicate that the function of liquid stabilizer reinforced soil is much better than lime reinforced soil.%对液体固化剂加固土进行了系统的试验研究,分析了利 用双电层理论加固土的强度形成机理,同时对液体固化剂加固土与石灰加固土的路用性能进 行了对比分析。结果表明,液体固化剂加固土具有优于石灰加固土的路用性能。

  4. 包裹式加筋土挡土墙抗震试验分析%Seismic Tests and Analysis of Warped Reinforced Earth-retaining Wall

    李庆海; 王炳锟; 蒋楚生; 段忠臣


    Research purposes: According to the engineering features of the Xiangyun Station of Guangtong-Dali Railway, the research was done on the reinforcing mechanism, load bearing, deformation, design methods, computing theory and the failure mode of the wraped reinforced earth-retaining wall under earthquake effect to improve the computing theory and numerical simulation method for the seismic design of the reinforced earth-retaining wall and promote the application of reinforced earth-retaining wall in engineering. Research conclusions; The warped reinforced earth-retaining wall is better than the ordinary earth-retaining wall in seismic property because the wrapped effect can make seismic wave weak during the propagation and amplification of the seismic wave along the wall up. When in 0. 4 g and 0. 616 g , the model produced the evident seismic fall, and cracks happened in the junctions between the wall panel and the reinforced soil and between the reinforced soil and the unreinforced soil. In the peak acceleration, the potential fracture surface of these two kinds of experimental models were distributed in the same position, approximate to 0.45 H vertical line. But in the "Code for Design of Retaining Structure of Railway Subgrade" (TB 10025-2006) , the potential fracture surface is approximate to 0.3 H vertical line and it slants to unsafety. So the reinforcing length should be increased in design. From the theoretical calculation and the analysis results of the internal and external stability of the reinforced earth-retaining wall obtained by the test data calculation, it was seen the coefficient of sliding resistance, the coefficient of capsizing resistance, the coefficient of uplifting resistance of the whole wall and the coefficient of uplifting resistance of the geogrid in various layers obtained by theoretical calculation were larger than the test data calculation. This showed the current code was unsafe and could be properly modified.%研究目的:针对广

  5. Desirable leaf traits for hydrological reinforcement of soil

    Boldrin D.


    Full Text Available Vegetation has an important influence on slope hydrology and hence slope stability via plant transpiration. Little is known about the relative merit of evergreen versus deciduous shrubs in maintaining suctions through the year. This study aims to quantify the soil-plant-water relations of two shrub species and to identify relevant plant traits that correlate with hydro-mechanical properties of vegetated soil. Corylus avellana L. (Hazel and Ilex aquifolium L. (Holly were chosen as contrasting deciduous and evergreen broadleaf species. For each species, three replicates were planted in separated pots of sandy loam soil. Each pot was irrigated until the soil was saturated and then was left to transpire for 20 days. Soil suction, leaf conductance to water vapour (gL and soil penetration resistance were recorded. After testing, some key plant traits were determined. It was found that Hazel dried soil faster than Holly. The mean suction induced by Hazel (82.9±1.5 kPa was 2.7 times greater than that induced by Holly (30.6±8.2 kPa, as Hazel has significantly higher gL and specific leaf area. Both suction and soil penetration resistance were strongly correlated with the total leaf area, but not the total leaf biomass.

  6. Experimental study of polyurethane foam reinforced soil used as a rock-like material

    Eren Komurlu


    Full Text Available In this study, polyurethane foam type thermoset polymerizing, due to chemical reaction between its liquid ingredients, was tested as binder after solidifying and then a rock-like material mixing with a sandy silt type soil was prepared. The uniaxial compressive strengths (UCSs of polyurethane foam reinforced soil specimens were determined for different polyurethane ratios in the mixture. Additionally, a series of tests on slake durability, impact value, freezing–thawing resistance, and abrasion resistance of polyurethane reinforced soil (PRS mixture was conducted. The UCS values over 3 MPa were measured from the PRS specimens. The testing results showed that treated soil can economically become a desirable rock-like material in terms of slake durability and resistances against freezing–thawing, impact effect and abrasion. As another characteristic of the rock-like material made with polyurethane foam, unit volume weight was found to be quite lower than those of natural rock materials.

  7. Experimental study of polyurethane foam reinforced soil used as a rock-like material

    Eren Komurlu; Ayhan Kesimal


    In this study, polyurethane foam type thermoset polymerizing, due to chemical reaction between its liquid ingredients, was tested as binder after solidifying and then a rock-like material mixing with a sandy silt type soil was prepared. The uniaxial compressive strengths (UCSs) of polyurethane foam reinforced soil specimens were determined for different polyurethane ratios in the mixture. Additionally, a series of tests on slake durability, impact value, freezingethawing resistance, and abrasion resistance of polyurethane reinforced soil (PRS) mixture was conducted. The UCS values over 3 MPa were measured from the PRS specimens. The testing results showed that treated soil can economically become a desirable rock-like material in terms of slake durability and resistances against freezingethawing, impact effect and abrasion. As another characteristic of the rock-like material made with polyurethane foam, unit volume weight was found to be quite lower than those of natural rock materials.

  8. Influence of Repeated Loading and Geosynthetic Reinforcement on Base Course Thickness over Soft Soil

    Slamet Widodo


    Full Text Available Vehicle wheels at surface of pavement will pass through it many times. Pavement or base course over soft soil always needs a reinforcement.  Influence of repeated loading to thickness of base course and base course reinforced by geosynthetic is presented. Several existing methods as Giroud-Han, USA Corps of Engineers and DuPont Typar method respectively to calculate thickness of base course over soft soil using reinforcement material either geotextile or geogrid is presented and the influence of repeated loading will be compared. Results from calculation and analysis indicate that Giroud-Han method gives thickness of base course higher than other methods when CBR values of subgrade at least 2 %.

  9. A Parametric Study of Stability of Geotextile-Reinforced Soil Above an Underground Cavity

    poor, Abbas Tahmasebi; Noorzad, R.; Shooshpasha, E.;


    A study based on two-dimensional finite element analyses under plane strain condition was performed by PLAXIS code to investigate the behavior of geotextilereinforced soil above an underground cavity. The effects of depth of single layer, tensile stiffness, number and length of reinforcement laye...

  10. Numerical simulation study on the compound reinforced gabion retaining wall of different reinforcing methods%复合加筋格宾挡墙不同加筋方式数值模拟研究

    丁立; 黄向京; 林伟平


    介绍了复合加筋格宾挡墙的单元组成及结构形式.采用FLAC3D深入研究了复合加筋格宾挡墙的力学响应,探讨了不同面板形式、不同加筋方式时墙面侧向变形和筋材拉力的分布规律,提出了复合加筋的最佳加筋方式.研究结果表明:加筋方式对面墙侧向位移的影响较大,交替加筋比分组加筋有更小的面墙侧向位移;保持加筋间距不变而减小加筋刚度比增大加筋层间距而增大筋材刚度更可取;在交替加筋的同时沿墙高适当减小加筋刚度可节省筋材费用.面墙形式、筋材布置方式对筋材拉力的大小和分布形式有重要影响.%The unit composition and structure of the composite reinforced gabion retaining wall is introduced. With the use of FLAC,the composite mechanical response of reinforced gabion retaining wall is deeply studied, the distribution of the lateral wall deformation and tensile reinforcement, when applying different panel types and different reinforcement methods, is discussed, and the the best reinforced composite reinforced way is put forward. The result has shown that;the reinforcement methods plays a great impact on the wall of lateral displacemen, the turn reinforced has a small wall reinforced lateral displacement than the score group. Instead of reducing the stiffness of reinforced, maitaining the same distance re-infored distance is more preferable than increasing reiforcement stillness with increasing the space between reinforced layers. Along the wall, with reducing the stiffness of the reinforcement appropriately while in turn reinforced, reinforcement cost is saved. Wall forms and reinforcement layout have a great influence on the size and the distribution of the tension reinforcement.

  11. Effect of plastic soil on a retaining wall subjected to surcharge loading

    Al-Juari Khawla


    Full Text Available The seasonal variation and climatic changes play a significant role that affects the stresses exerted on a retaining wall, and the state of stresses in the soil mass behind the wall especially for highly expansive soil. These stresses resulted in the wall moving either away or towards the soil. In this study, a laboratory physical model of the retaining wall formed of a box having (950×900×600 mm dimensions with one side representing the wall being developed. After the soil being laid out in the box in specified layers, specified conditions of saturation and normal stresses were applied. The wall is allowed to move horizontally in several distances (0.1, 0.2, 0.3, 0.6, 0.8, 1.0 , 2.0, 3.0 and 4.0 mm, and the stresses being measured, then the vertical loading was released. The main measured variables during the tests are; the active and passive earth pressures, vertical movement of the soil, total suction and time. Results showed that the lateral earth pressure along the depth of the wall largely decreased when wall moved away from the soil. Total suction was slightly affected during wall’s movement. At unloading stage, the lateral earth pressure decreased at the upper half of wall height, but increased at the other wall part. Total suction was increased at all depths during this stage.

  12. Study on reinforcement of soil for suppressing fugitive dust by bio-cementitious material

    Zhan, Qiwei; Qian, Chunxiang


    Microbial-induced reinforcement of soil, as a new green and environmental-friendly method, is being paid extensive attention to in that it has low cost, simple operation and rapid effects. In this research, reinforcement of soil for suppressing fugitive dust by bio-cementitious material was investigated. Soil cemented by bio-cementitious material had superior mechanical properties, such as hardness, compressive strength, microstructure, wind-erosion resistance, rainfall-erosion resistance and freeze-thaw resistance. The average hardness of sandy soil, floury soil and clay soil is 18.9 º, 25.2 º and 26.1 º, while average compressive strength of samples is 0.43 MPa, 0.54 MPa and 0.69 MPa, respectively; meanwhile, the average calcite content of samples is 6.85 %, 6.09 %, and 5.96 %, respectively. Compared with the original sandy soil, floury soil and clay soil, the porosity decreases by 38.5 %, 33.7 % and 29.2 %. When wind speed is 12 m/s, the mass loss of sandy soil, floury soil and clay soil cemented by bio-cementitious material are all less than 30 g/(m2·h). After three cycles of rainfall erosion of 2.5 mm/h, the mass loss are less than 25 g/(m2·h) and the compressive strength residual ratio are more than 98.0 %. Under 25 cycles of freeze-thaw, the mass loss ratio are less than 3.0 %.

  13. Study on the effect of the infill walls on the seismic performance of a reinforced concrete frame

    Zhang, Cuiqiang; Zhou, Ying; Zhou, Deyuan; Lu, Xilin


    Motivated by the seismic damage observed to reinforced concrete (RC) frame structures during the Wenchuan earthquake, the effect of infill walls on the seismic performance of a RC frame is studied in this paper. Infill walls, especially those made of masonry, offer some amount of stiffness and strength. Therefore, the effect of infill walls should be considered during the design of RC frames. In this study, an analysis of the recorded ground motion in the Wenchuan earthquake is performed. Then, a numerical model is developed to simulate the infill walls. Finally, nonlinear dynamic analysis is carried out on a RC frame with and without infill walls, respectively, by using CANNY software. Through a comparative analysis, the following conclusions can be drawn. The failure mode of the frame with infill walls is in accordance with the seismic damage failure pattern, which is strong beam and weak column mode. This indicates that the infill walls change the failure pattern of the frame, and it is necessary to consider them in the seismic design of the RC frame. The numerical model presented in this paper can effectively simulate the effect of infill walls on the RC frame.

  14. Drying Shrinkage of Recycled Aggregate Reinforced Concrete Shear Wall%再生骨料钢筋混凝土剪力墙干燥收缩性能

    崔正龙; 庄宇; 汪振双


    在约束条件下对再生骨科钢筋混凝土剪力墙和普通钢筋混凝土剪力墙进行了干燥收缩应变测试,同时观察墙体表面干燥收缩裂缝产生的情况.结果表明:2种剪力墙内部收缩应变均明显小于相应的外表面收缩应变;2种剪力墙内部收缩应变相差不大;再生骨料钢筋混凝土剪力墙外表面收缩应变明显比普通钢筋混凝土剪力墙小,而细微收缩裂缝则明显增多.%Drying shrinkage strains of recycled aggregate reinforced concrete shear wall and common reinforced concrete shear wall were measured under constraint conditions, and cracks situations on shear wall surface were observed. The results reveal that for recycled aggregate reinforced concrete shear wall and common reinforced concrete shear wall, the internal shrinkage strain are obviously less than surface shrinkage strain. There is a little difference of internal shrinkage strains between recycled aggregate reinforced concrete shear wall and common reinforced concrete shear wall. The surface shrinkage strain of recycled aggregate reinforced concrete shear wall is obviously lower than that of common reinforced concrete shear wall, while micro shrinkage cracks is obviously more than the latter.

  15. Alternativa estructural de refuerzo horizontal en muros de mampostería Structural alternative of horizontal reinforcement in masonry walls

    Diego Fernando Páez Moreno


    Full Text Available La implementación de refuerzo horizontal en muros de mampostería con ladrillo macizo de arcilla cocida es una técnica empleada en varios países. En este trabajo se propone un análisis para muros de mampostería representativos de la ciudad de Tunja con la implementación de grafiles de acero como alternativa de refuerzo horizontal. Este estudio involucra la definición de los tipos de materiales a emplear, las características de los muros a ensayar y las variables que se deben aplicar, tanto en los muros como en la ejecución del ensayo de compresión diagonal, que define tipos de muros con características propias de refuerzo. Los resultados del proceso de análisis del comportamiento individual y general de los muros de mampostería sometidos al ensayo de compresión diagonal permiten identificar la variación del esfuerzo cortante representativo para cada tipo de muro, en relación con el refuerzo empleado en los diferentes modelos y la tipología de falla.Implementation of horizontal reinforcement in masonry walls with solid cooked clay bricks is a commonly used technique in several countries. This article is intended to analyze masonry walls representatives of Tunja City, with implementation of small steel bars as an alternative of horizontal reinforcement. This study involves definition of types of materials to be used, characteristics of walls to be tested, and variables which should be applied in both walls and during the execution of the diagonal compression test which defines the types of walls with own characteristics of reinforcement. Results from individual and general behavior analysis process of masonry walls subject to diagonal compression tests allow identifying variation of shear stress for each kind of wall, in relation to reinforcement used in several models and failure typology.

  16. Magnesia tuned multi-walled carbon nanotubes–reinforced alumina nanocomposites

    Ahmad, Iftikhar, E-mail: [Center of Excellence for Research in Engineering Materials, Advanced Manufacturing Institute, King Saud University, P.O. Box. 800, Riyadh 11421 (Saudi Arabia); Islam, Mohammad; Dar, Mushtaq Ahmad [Center of Excellence for Research in Engineering Materials, Advanced Manufacturing Institute, King Saud University, P.O. Box. 800, Riyadh 11421 (Saudi Arabia); Xu, Fang [Division of Materials, Mechanics and Structure, Faculty of Engineering, University of Nottingham, University Park, NG7 2RD (United Kingdom); Shah, Syed Ismat [Department of Materials Science and Engineering, University of Delaware, Newark, DE 19716 (United States); Zhu, Yanqiu [College of Engineering, Mathematics and Physical Sciences, University of Exeter, Exeter EX4 4QF (United Kingdom)


    Magnesia tuned alumina ceramic nanocomposites, reinforced with multi-walled carbon nanotubes, were condensed using pressureless and hot-press sintering processes. Densification, microstructure and mechanical properties of the produced nanocomposites were meticulously investigated. Electron microscopy studies revealed the homogenous carbon nanotube dispersion within the alumina matrix and confirmed the retention of carbon nanotubes' distinctive tubular morphology and nanoscale features during the extreme mixing/sintering processes. Pressureless sintered nanocomposites showed meagre mechanical responses due to the poorly-integrated microstructures with a slight improvement upon magnesia addition. Conversely, both the magnesia addition and application of hot-press sintering technique resulted in the nanocomposite formation with near-theoretical densities (~ 99%), well-integrated microstructures and superior mechanical properties. Hot-press sintered nanocomposites incorporating 300 and 600 ppm magnesia exhibited an increase in hardness (10 and 11%), flexural strength (5 and 10%) and fracture toughness (15 and 20%) with respect to similar magnesia-free samples. Compared to monolithic alumina, a decent rise in fracture toughness (37%), flexural strength (22%) and hardness (20%) was observed in the hot-press sintered nanocomposites tuned with merely 600 ppm magnesia. Mechanically superior hot-press sintered magnesia tailored nanocomposites are attractive for several load-bearing structural applications. - Highlights: • MgO tailored Al{sub 2}O{sub 3}–2 wt.% CNT nanocomposites are presented. • The role of MgO and sintering on nanocomposite structures and properties was studied. • Well-dispersed CNTs maintained their morphology/structure after harsh sintering. • Hot-pressing and MgO led nanocomposites to higher properties/unified structures. • MgO tuned composites showed higher toughness (37%) and strength (22%) than Al{sub 2}O{sub 3}.

  17. Hydroxyapatite reinforced with multi-walled carbon nanotubes and bovine serum albumin for bone substitute applications

    Gholami, Fatemeh; Noor, Ahmad-Fauzi Mohd


    The similarity of the chemical composition of HA to the mineral phase of bone and its excellent biocompatibility meets the requirement of materials designed for bone substitute purpose. The application of HA in load bearing devices is limited by its poor mechanical properties. CNTs with outstanding stiffness, strength, combined with their small size and large interfacial area, suggest that they may have great potential as a reinforcing agent for HA. This work aims to develop the Hydroxyapatite/Multi-walled Carbon Nanotubes/Bovine Serum Albumin (HA/MWCNTs/BSA) composites with different types of MWCNTs including hydroxylated and carboxylated MWCNTs (MWCNTs-OH, MWCNTs-COOH), and evaluation of mechanical strength and in vitro cellular response of developed composites. HA powder was mixed with de-ionized water, 15 wt.% BSA, and 0.5 wt.% of different MWCNTs* (> 95%), MWCNTs (> 99.9%), MWCNTs-OH (> 99.9%), MWCNTs-COOH (> 99.9%) to produce composites. Among all developed composites, the HA/MWCNTs-COOH/BSA shows the highest compressive strength (29.57 MPa). The cytotoxic effect of HA/MWCNTs-COOH/BSA with different concentrations (6.25 to 200 µg/ml) was evaluated by MTT assay against normal human colon fibroblast (CCD-18Co cell line). At low concentration, all developed composites were found to be non-cytotoxic when treated to the human fibroblast cells and did not elicit cytotoxic effects on cell proliferation and the highest values of cell viability (283%) for the HA/MWCNTs-COOH/BSA composites obtained; whereas when the concentration was increased, the reduction in cell viability was observed. The novel composites showed favorable cytocompatibility with improved compressive strength which make it applicable to use in range of trabecular bone.

  18. Spark plasma sintering of silicon carbide and multi-walled carbon nanotube reinforced zirconium diboride ceramic composite

    Yadhukulakrishnan, Govindaraajan B.; Rahman, Arif; Karumuri, Sriharsha [School of Mechanical and Aerospace Engineering Oklahoma State University, Stillwater, OK 74078 (United States); Stackpoole, Margaret M. [ELORET Corporation, Moffett Field, CA 94035 (United States); Kalkan, A. Kaan; Singh, Raman P. [School of Mechanical and Aerospace Engineering Oklahoma State University, Stillwater, OK 74078 (United States); Harimkar, Sandip P., E-mail: [School of Mechanical and Aerospace Engineering Oklahoma State University, Stillwater, OK 74078 (United States)


    Highlights: Black-Right-Pointing-Pointer Dense SiC and carbon nanotube reinforced ZrB{sub 2} composites were spark plasma sintered. Black-Right-Pointing-Pointer SiC and carbon nanotube reinforcement favored the densification of ZrB{sub 2} composites. Black-Right-Pointing-Pointer SiC and carbon nanotube reinforcement resulted in toughening of ZrB{sub 2} composites. Black-Right-Pointing-Pointer Carbon nanotubes were retained in the spark plasma sintered ZrB{sub 2} composites. - Abstract: In this paper spark plasma sintering (SPS) of silicon carbide and multi-walled carbon nanotube reinforced zirconium diboride ultra-high temperature ceramic matrix composites is reported. Systematic investigations on the effect of reinforcement type (SiC and CNTs) and content (10-40 vol.% SiC and 2-6 vol.% CNTs) on densification behavior, microstructure development, and mechanical properties (microhardness, bi-axial flexural strength, and indentation fracture toughness) are presented. With the similar SPS processing parameters (1900 Degree-Sign C, 70 MPa pressure, and 15 min soaking time), near-full densification (>99% relative density) was achieved with 10-40% SiC (in ZrB{sub 2}-SiC) and 4-6% CNT (in ZrB{sub 2}-CNT) reinforced composites. The SiC and CNT reinforcement further improved the indentation fracture toughness of the composites through a range of toughening mechanisms, including particle shearing, crack deflection at the particle-matrix interface, and grain pull-outs for ZrB{sub 2}-SiC composites, and CNT pull-outs and crack deflection in ZrB{sub 2}-CNT composites.

  19. Comparison of the Structural Performance of Monolithic and Precast Reinforced Concrete Core Walls

    Nakachi, Tadaharu


    In the core wall system in high-rise buildings, the four L-shaped core walls at the center effectively reduce seismic vibration. On the other hand, precast core walls are effective for construction because they can be built more quickly than cast-in-place core walls. In this study, a lateral loading test was conducted on a monolithic wall column simulating the corner and the area near the corner of an L-shaped core wall. The test results were compared with those of a precast wall column teste...

  20. Numerical analysis of effect of friction between diaphragm wall and soil on braced excavation

    刁钰; 郑刚


    A plane strain finite element model was established to investigate the effect of friction between diaphragm wall and soil on braced excavation. The behavior of interface between diaphragm wall and soil was simulated with the interface model of ABAQUS. Parametric studies were conducted with different diaphragm wall external friction angles δ. The results show that deflection of diaphragm wall and ground surface settlement decrease with the decrease of δ. However, the reduction effect on diaphragm wall deflection is the most significant at the depth where the maximum wall deflection occurs and can be neglected at the wall base. The ratio between wall deep inward component and wall cantilever component reaches its peak value 2.7 when δ=5°. The ratio of the maximum ground surface settlement to the maximum wall lateral deflection decreases at a reduced rate with the increase of δ. For excavation with braced diaphragm wall, the effect of friction between diaphragm and soil on the deflection of diaphragm wall and ground settlement, especially the distribution of ground surface settlement behind diaphragm, should be taken into account.

  1. Infilled masonry walls contribution in mitigating progressive collapse of multistory reinforced concrete structures according to UFC guidelines

    Helmy, Huda; Hadhoud, Hamed; Mourad, Sherif


    A structure is subjected to progressive collapse when an element fails, resulting in failure of adjoining structural elements which, in their turn, cause further structural failure leading eventually to partial or total collapse. The failure of a primary vertical support might occur due to extreme loadings such as bomb explosion in a terrorist attack, gas explosion and huge impact of a car in the parking area. Different guidelines such as the General Services Administration (GSA 2003) and the Unified Facilities Criteria (UFC 2009) addressed the structural progressive collapse due to the sudden loss of a main vertical support. In the current study, a progressive collapse assessment according to the UFC guidelines is carried out for a typical ten-story reinforced concrete framed structure designed according to codes [(ACI 318-08) and (ASCE 7-10)] for minimum design loads for buildings and other structures. Fully nonlinear dynamic analysis for the structure was carried out using Applied Element Method (AEM). The investigated cases included the removal of a corner column, an edge column, an edge shear wall, internal columns and internal shear wall. The numerical analysis showed that simplification of the problem into 3D bare frames would lead to uneconomical design. It was found for the studied case that, the infilled masonry walls have a valuable contribution in mitigating progressive collapse of the reinforced concrete framed structures. Neglecting these walls would lead to uneconomical design.

  2. The self-reinforcing feedback between low soil fertility and chronic poverty

    Barrett, Christopher B.; Bevis, Leah E. M.


    Most of the world's extreme poor, surviving on US$1.25 or less per day, live in rural areas and farm for a living. Many suffer chronic poverty that lasts for years or generations, rather than the transitory poverty that dominates developed, urban economies. Such chronic, structural poverty arises when an individual's productive assets -- such as their ability to work or their soils -- and the technologies and markets that transform their assets into food and income are insufficient to attain satisfactory living standards. Research reveals strong links between economic status and soil quality, and these can be self-reinforcing. For example, poor soil constrains agricultural production and household capital, and low household capital constrains investments in improving soils. Price, availability and access to credit can limit farmers' applications of nutrients, which are often the primary constraint on agricultural productivity. Soil micronutrient deficiencies can lead to dietary mineral deficiencies and negative health outcomes that further constrain productivity and household asset accumulation. Soils may also be important for smallholder resilience to stressors and shocks. For example, high-quality soil can reduce vulnerability to drought, and insurance against risk may promote investment in soils. Interventions such as fertilizer subsidies, micronutrient-fortified fertilizer and improved access to information, insurance and credit may all help break the soil-poverty cycle.

  3. Case Study on Soft Soil Improvement using Innovative and Cost-Effective Reinforcing Techniques

    Endra Susila


    Full Text Available This paper describes, discusses and compares three new innovations of reinforcement systems for soft soils: (a a combination of gridded matrass and piles of bamboo, (b a combination of matrass and piles of bamboo, and (c a group of mini piles connected by small H-beams with a compacted top layer to hold the top mini piles. First, illustrations and applications of the three types of reinforcement are described from three full-scale field works. Technical bases for the three types are presented, while technical comparisons are discussed next. Finally, conclusions are developed. The case studies, analysis results, and full-scale fieldwork verifications show that the three reinforcement systems have worked properly. Each system has its own advantages and disadvantages in terms of construction duration and cost, capability/effectiveness and material availability, especially in rural areas.

  4. An examination of the earthquake behaviour of a retaining wall considering soil-structure interaction

    Köktan, Utku; Demir, Gökhan; Kerem Ertek, M.


    The earthquake behavior of retaining walls is commonly calculated with pseudo static approaches based on Mononobe-Okabe method. The seismic ground pressure acting on the retaining wall by the Mononobe-Okabe method does not give a definite idea of the distribution of the seismic ground pressure because it is obtained by balancing the forces acting on the active wedge behind the wall. With this method, wave propagation effects and soil-structure interaction are neglected. The purpose of this study is to examine the earthquake behavior of a retaining wall taking into account the soil-structure interaction. For this purpose, time history seismic analysis of the soil-structure interaction system using finite element method has been carried out considering 3 different soil conditions. Seismic analysis of the soil-structure model was performed according to the earthquake record of "1971, San Fernando Pacoima Dam, 196 degree" existing in the library of MIDAS GTS NX software. The results obtained from the analyses show that the soil-structure interaction is very important for the seismic design of a retaining wall. Keywords: Soil-structure interaction, Finite element model, Retaining wall

  5. Effect of Bearing Capacity of Strip Footing on Reinforced Double Layer Soil System with Fly ash Stabilized Clayey Soil

    Love Sharma


    Full Text Available This research was performed to investigate the effect of bearing capacity of strip footing on geogrid reinforced sand overlay on stabilized expansive soil (i.e. double layer soil system and check the different parameters contributing to their performance using laboratory model tank tests. The parameters investigated in this study include H/B (thickness of top sandy layer to width of footing u/B (location of the 1st layer of reinforcement to width of footing, h/B (vertical spacing between consecutive geogrid layers to width of footing, b/B (length of the geogrid layer to width of footing. The effect of different H/B ratios and geogrid reinforcement N values on the bearing capacity ration (BCR and settlement reduction ratio (SRR were also investigated. The results show that bearing capacity increases significantly with increasing the H/B ratio as well as number of geogrid layers. The bearing capacity for the soil increases with an average of 12.35% using H/B equal to0.5 and the bearing capacity increases with an average of 35.76%, 75.56% & 230.83% while using H/B equal to 1.0, 1.5 & 2.0. It also found that the use of sandy layers over flyash mixed clayey soil has a considerable effect on the bearing capacity characteristics and the use of geogrid layers in the granular overlay has remarkable effect on Bearing capacity ratio (BCR & Settlement reduction ratio (SRR.

  6. Strength Design of Reinforced Concrete Hydraulic Structures; Report 3, T-Wall Design.


    Concrete Reinforcing Steel Institute. 1978. CRSI Handbook, 3rd ed. Federation Internationale de la Precontrainte (FIP). 1974. "Recommen- dations for... concrete cover to the stirrups and main steel of a bridge floor beam that has been completely spalled off due to severe steel corrosion. 12. In this...Corrosion damage to a bridge floor beam C6 Tensile crack exposure tests by WES 13. Two series of reinforced concrete beams were made and exposed to


    D. Koteswara Rao,


    Full Text Available Majority of the population in India are living in costal corridor, where the existing soils are weak and more deformative. It is becoming a great challenge for the civil engineers to design suitable foundation for the structures in these regions. The effect of GBFS, lime and geotextile as reinforcement & separator on the marine clay foundation soil bed in field has been investigated. A test track of 8m long and 2m wide was laid in the field for testing the treated and untreated conditions of the marine clay foundation soil beds. The ultimate load carrying capacity of the test tracks for untreated and treated conditions have been studied and also the degree of compaction of the test tract was found.

  8. Design of reinforced concrete walls casted in place for the maximum normal stress of compression

    T. C. Braguim

    Full Text Available It is important to evaluate which designing models are safe and appropriate to structural analysis of buildings constructed in Concrete Wall system. In this work it is evaluated, through comparison of maximum normal stress of compression, a simple numerical model, which represents the walls with frame elements, with another much more robust and refined, which represents the walls with shells elements. The designing of the normal stress of compression it is done for both cases, based on NBR 16055, to conclude if the wall thickness initially adopted, it is enough or not.

  9. [Species-associated differences in foliage-root coupling soil-reinforcement and anti-erosion].

    Liu, Fu-quan; Liu, Jing; Nao, Min; Yao, Xi-jun; Zheng, Yong-gang; Li, You-fang; Su, Yu; Wang, Chen-jia


    This paper took four kinds of common soil and water conservation plants of the study area, Caragana microphylla, Salix psammophila, Artemisia sphaerocephala and Hippophae rhamnides at ages of 4 as the research object. Thirteen indicators, i.e., single shrub to reduce wind velocity ration, shelterbelt reducing wind velocity ration, community reducing wind velocity ration, taproot tensile strength, representative root constitutive properties, representative root elasticity modulus, lateral root branch tensile strength, accumulative surface area, root-soil interface sheer strength, interface friction coefficient, accumulative root length, root-soil composite cohesive, root-soil composite equivalent friction angle, reflecting the characteristics of windbreak and roots, were chose to evaluate the differences of foliage-root coupling soil-reinforcement and anti-erosion among four kinds of plants by analytic hierarchy process (AHP) under the condition of spring gale and summer rainstorm, respectively. The results showed the anti-erosion index of foliage-root coupling was in the sequence of S. psammophila (0.841) > C. microphylla (0.454) > A. sphaerocephala (-0.466) > H. rhamnides (-0.829) in spring gale, and C. microphylla (0.841) > S. psammophila (0. 474) > A. sphaerocephala (-0.470) > H. rhamnides (-0.844) in summer rainstorm. S. psammophila could be regarded as one of the most important windbreak and anti-erosion species, while C. microphylla could be the most valuable soil and water conservation plant for the study area.

  10. An assessment of models that predict soil reinforcement by plant roots

    Hallett, P. D.; Loades, K. W.; Mickovski, S.; Bengough, A. G.; Bransby, M. F.; Davies, M. C. R.; Sonnenberg, R.


    Predicting soil reinforcement by plant roots is fraught with uncertainty because of spatio-temporal variability, the mechanical complexity of roots and soil, and the limitations of existing models. In this study, the validity of root-reinforcement models was tested with data from numerous controlled laboratory tests of both fibrous and woody root systems. By using pot experiments packed with homogeneous soil, each planted with one plant species and grown in glasshouses with controlled water and temperature regimes, spatio-temporal variability was reduced. After direct shear testing to compare the mechanical behaviour of planted versus unplanted samples, the size distribution of roots crossing the failure surface was measured accurately. Separate tensile tests on a wide range of root sizes for each test series provided information on the scaling of root strength and stiffness, which was fitted using power-law relationships. These data were used to assess four root-reinforcement models: (1) Wu et al.'s (1979) root-reinforcement model, (2) Rip-Root fibre bundle model (FBM) proposed by Pollen & Simon (2005), (3) a stress-based FBM and (4) a strain-based FBM. For both fibrous (barley) and woody (willow) root systems, all of the FBMs provided a better prediction of reinforcement than Wu's root-reinforcement model. As FBMs simulate progressive failure of roots, they reflect reality better than the Wu model which assumes all roots break (and contribute to increased shear strength) simultaneously. However, all of the FBMs contain assumptions about the distribution of the applied load within the bundle of roots and the failure criterion. The stress-based FBM assumes the same stiffness for different sized roots, resulting in progressive failure from the largest to smallest roots. This is not observed in testing where the smallest roots fail first. The Rip-Root FBM predicts failure from smallest to largest roots, but the distribution of load between different sized roots is


    D. Koteswara Rao,


    Full Text Available India being peninsular country has large area coming under coastal region and also it has been the habitat for considerable percentage of population. The marine clays are generally found in the coastal region of West Bengal, Orissa, Andhra Pradesh, Tamilnadu, Kerala, Karnataka, Maharashtra and some parts of Gujarat. Marine or soft clays exists in these region are weak and deformative in nature. The present study deals with the strength characteristics of the marine clay collected from Kakinada Sea Port Ltd, Kakinada, A.P, India. The effect of lime on the strength characteristics of marine clay are studied in this investigation along with the reinforcement effect using geotextile as reinforcement and separator for the foundation soil bed.

  12. Composite Behavior of a Novel Insulated Concrete Sandwich Wall Panel Reinforced with GFRP Shear Grids: Effects of Insulation Types

    JunHee Kim


    Full Text Available A full-scale experimental program was used in this study to investigate the structural behavior of novel insulated concrete sandwich wall panels (SWPs reinforced with grid-type glass-fiber-reinforced polymer (GFRP shear connectors. Two kinds of insulation-expanded polystyrene (EPS and extruded polystyrene (XPS with 100 mm thickness were incased between the two concrete wythes to meet the increasing demand for the insulation performance of building envelope. One to four GFRP shear grids were used to examine the degree of composite action of the two concrete wythes. Ten specimens of SWPs were tested under displacement control subjected to four-point concentrated loads. The test results showed that the SWPs reinforced with GFRP grids as shear connectors developed a high degree of composite action resulting in high flexural strength. The specimens with EPS foam exhibited an enhanced load-displacement behavior compared with the specimens with XPS because of the relatively stronger bond between insulation and concrete. In addition, the ultimate strength of the test results was compared to the analytical prediction with the mechanical properties of only GRFP grids. The specimens with EPS insulation presented higher strength-based composite action than the ones with XPS insulation.

  13. Experimental Study on the Seismic Performance of Recycled Concrete Brick Walls Embedded with Vertical Reinforcement

    Wanlin Cao


    Full Text Available Recycled concrete brick (RCB is manufactured by recycled aggregate processed from discarded concrete blocks arising from the demolishing of existing buildings. This paper presents research on the seismic performance of RCB masonry walls to assess the applicability of RCB for use in rural low-rise constructions. The seismic performance of a masonry wall is closely related to the vertical load applied to the wall. Thus, the compressive performance of RCB masonry was investigated firstly by constructing and testing eighteen RCB masonry compressive specimens with different mortar strengths. The load-bearing capacity, deformation and failure characteristic were analyzed, as well. Then, a quasi-static test was carried out to study the seismic behavior of RCB walls by eight RCB masonry walls subjected to an axial compressive load and a reversed cyclic lateral load. Based on the test results, equations for predicting the compressive strength of RCB masonry and the lateral ultimate strength of an RCB masonry wall were proposed. Experimental values were found to be in good agreement with the predicted values. Meanwhile, finite element analysis (FEA and parametric analysis of the RCB walls were carried out using ABAQUS software. The elastic-plastic deformation characteristics and the lateral load-displacement relations were studied.

  14. Experimental Study on the Seismic Performance of Recycled Concrete Brick Walls Embedded with Vertical Reinforcement

    Cao, Wanlin; Zhang, Yongbo; Dong, Hongying; Zhou, Zhongyi; Qiao, Qiyun


    Recycled concrete brick (RCB) is manufactured by recycled aggregate processed from discarded concrete blocks arising from the demolishing of existing buildings. This paper presents research on the seismic performance of RCB masonry walls to assess the applicability of RCB for use in rural low-rise constructions. The seismic performance of a masonry wall is closely related to the vertical load applied to the wall. Thus, the compressive performance of RCB masonry was investigated firstly by constructing and testing eighteen RCB masonry compressive specimens with different mortar strengths. The load-bearing capacity, deformation and failure characteristic were analyzed, as well. Then, a quasi-static test was carried out to study the seismic behavior of RCB walls by eight RCB masonry walls subjected to an axial compressive load and a reversed cyclic lateral load. Based on the test results, equations for predicting the compressive strength of RCB masonry and the lateral ultimate strength of an RCB masonry wall were proposed. Experimental values were found to be in good agreement with the predicted values. Meanwhile, finite element analysis (FEA) and parametric analysis of the RCB walls were carried out using ABAQUS software. The elastic-plastic deformation characteristics and the lateral load-displacement relations were studied. PMID:28788170

  15. Material Properties and Tensile Behaviors of Polypropylene Geogrid and Geonet for Reinforcement of Soil Structures


    The properties and tensile behaviors of polypropylene (PP) geogrids and geonets for reinforcement of soil structures are investigated.Mass per unit area of the geogrids and geonets was weighed using an electronic balance and aperture sizes of the geonets were exactly measured using a computer.Laboratory tests were performed using a small tensile machine capable of monitoring tensile force and displacement.Tensile failure behaviors were described,and tensile index properties such as tensile strength,maximum tensile strain,tensile forces corresponding to different strains in the geogrids and gronets were obtained.The characterization of these indexes is discussed.

  16. Discussion on the construction technology of reinforced concrete shear wall structure%钢筋混凝土剪力墙结构施工技术



    Through the summary of the construction of the reinforced concrete shear wall structure in engineering projects, from the shear wall formwork construction, installation and positioning, reinforced concrete construction quality control, door and window openings to the matters needing attention in the construction and other aspects of the high-rise buildings of reinforced concrete shear wall construction technology control points.%经过对工程项目中钢筋混凝土剪力墙结构的施工总结,从剪力墙的模板工程施工、钢筋的安装和定位、混凝土的施工质量控制、门窗洞口处施工注意事项等方面探讨了高层建筑钢筋混凝土剪力墙结构施工的技术控制要点。

  17. Experiments on Hybrid Precast Concrete Shear Walls Emulating Monolithic Construction with Different Amounts of Posttensioned Strands and Different Debond Lengths of Grouted Reinforcements

    Zhangfeng Zhu


    Full Text Available This paper proposed a hybrid precast concrete shear wall emulating monolithic construction (HPWEM that utilized grouted vertical connecting reinforcements and unbonded posttensioned high-strength strands across the horizontal joint for the lateral resistance. The grouted reinforcements with predetermined debond length were used to provide strength by tension and energy dissipation by yielding. The posttensioned strands were mainly employed to offer the restoring force to reduce the residual displacement by elastic extension. The overlapping welded closed stirrups improved the confinement property of the restrained concrete, avoiding the brittle failure. Six HPWEM specimens, considering variables including the amounts of strands and the debond lengths of grouted reinforcements, as well as one referenced cast-in-place monolithic wall specimen, were tested under the low-cycle reversed lateral load. The HPWEM specimens were capable of providing strength, stiffness, ductility, and energy dissipation equivalent to that of the monolithic wall specimen under certain variable condition.

  18. Responses of soil ammonia-oxidizing microorganisms to repeated exposure of single-walled and multi-walled carbon nanotubes.

    Chen, Qinglin; Wang, Hui; Yang, Baoshan; He, Fei; Han, Xuemei; Song, Ziheng


    The impacts of carbon nanotubes (CNTs) including single-walled carbon nanotubes (SWNTs) and multi-walled carbon nanotubes (MWNTs) on soil microbial biomass and microbial community composition (especially on ammonium oxidizing microorganisms) have been evaluated. The first exposure of CNTs lowered the microbial biomass immediately, but the values recovered to the level of the control at the end of the experiment despite the repeated addition of CNTs. The abundance and diversity of ammonium-oxidizing archaea (AOA) were higher than that of ammonium-oxidizing bacteria (AOB) under the exposure of CNTs. The addition of CNTs decreased Shannon-Wiener diversity index of AOB and AOA. Two-way ANOVA analysis showed that CNTs had significant effects on the abundance and diversity of AOB and AOA. Dominant terminal restriction fragments (TRFs) of AOB exhibited a positive relationship with NH4(+), while AOA was on the contrary. It implied that AOB prefer for high-NH4(+) soils whereas AOA is favored in low NH4(+) soils in the CNT-contaminated soil. Copyright © 2014 Elsevier B.V. All rights reserved.

  19. 加筋格宾挡墙动力特性分析及设计要点%Feature Analysis and Design Discussion for Reinforced Gabion Retaining Wall

    刘兆生; 姚令侃; 朱宏伟; 刘敏


    通过室内拉拔试验研究了格宾网筋土作用特性,利用振动台试验研究了加筋格宾挡墙的动力特性,分析了它在地震荷载下的破坏现象及其动土压力分布规律,并找出其在地震荷载下的最不利部位,提出了加强措施;利用Geo-Studio软件建立人工耦合有限元数值模拟模型,对比分析了振动台试验及相同尺寸的有限元数值模拟模型,研究加筋格宾挡墙的动力特性;分别建立了4种相同尺寸的模型,研究加筋格宾挡墙体系在整体受力体系中格宾挡墙及墙后加筋的影响.%The properties of gabion mesh Role properties are examined by the indoor pull-out test, the dynamic features of reinforced gabion retaining wall analysis are studied through shaking table test, analyzing the destruction under seismic loading and the failure law of its ground breaking pressure, to find out the worst part of reinforced gabion retaining wall under seismic loading and provide Related measures for enforcing the wall. Geo-Studio software, using an artificial coupling finite element numerical simulation model, compares analytically the results of shaking table model test and the finite element numerical simulation with the same size, to further study the dynamic characteristics of reinforced gabion retaining wall, Study reinforced gabion retaining wall system in the overall force system gabion retaining wall and the wall reinforcement effects.

  20. Crystallization and melting behavior of multi-walled carbon nanotube-reinforced nylon-6 composites

    Phang, In Yee; Ma, Jianhua; Shen, Lu; Liu, Tianxi; Zhang, Wei-De


    The crystallization and melting behavior of neat nylon-6 (PA6) and multi-walled carbon nanotubes (MWNTs)/PA6 composites prepared by simple melt-compounding was comparatively studied. Differential scanning calorimetry (DSC) results show two crystallization exotherms (TCC, 1 and TCC, 2) for PA6/MWNTs

  1. Crystallization and melting behavior of multi-walled carbon nanotube-reinforced nylon-6 composites

    Phang, In Yee; Ma, Jianhua; Shen, Lu; Liu, Tianxi; Zhang, Wei-De


    The crystallization and melting behavior of neat nylon-6 (PA6) and multi-walled carbon nanotubes (MWNTs)/PA6 composites prepared by simple melt-compounding was comparatively studied. Differential scanning calorimetry (DSC) results show two crystallization exotherms (TCC, 1 and TCC, 2) for PA6/MWNTs

  2. Analysis of interlaminar fracture toughness and damage mechanisms in composite laminates reinforced with sprayed multi-walled carbon nanotubes

    Almuhammadi, Khaled


    The present work is focused on the nanoreinforcement of prepreg based carbon fiber composite laminates to improve delamination resistance. Functionalized multi-walled carbon nanotubes (MWCNTs) were dispersed over the interface between prepreg layers through solvent spraying and the resulting mode I interlaminar fracture toughness was determined. For comparison, baseline samples with neat prepregs were also prepared. Results indicate that the introduction of functionalized MWCNTs can favorably affect the interlaminar fracture toughness, and the associated mechanisms of failure have been investigated. The manufacturing procedures and the interfacial reinforcing mechanism were explored by analyzing (i) the wettability between CNTs-solvent solution and prepreg surface, (ii) CNTs dispersion and (iii) the fractured surfaces through high resolution scanning electron microscopy and Raman mapping. © 2013 Elsevier Ltd.


    璩继立; 赵冬雪; 李贝贝


    To improve the characteristics of the low Shanghai clay strength and easy destroy, the dispersed palm was mixed into Shanghai clay with different mass reinforcement ratio and aspect ratio to do unconfined compressive strength test and Brazilian splitting test, then the impact of reinforced conditions on the compressive strength and tensile strength was explored.The results showed that compared with plain soil, palm reinforced soil could increase the compressive strength and tensile strength of Shanghai clay. The most appropriate reinforcement ratio of compressive strength and tensile strength in test was 1.00%.The best palm length was 4 mm, the optimum aspect ratio was 1∶3.Compared with plain soil, the improved degree of tensile strength by reinforcement was higher than that of the compressive strength.Meanwhile it was analyzed the mechanism of raising the strength of palm reinforced soil.%为改良上海黏土强度低,易发生破坏的特性,将分散的棕榈片以不同质量加筋率、长宽比等加入上海黏土中进行抗压强度试验和巴西劈裂试验,来探究加筋条件对棕榈加筋土抗压强度和抗拉强度的影响。试验结果表明:与素土相比,棕榈加筋土可提高上海黏土的抗压强度和抗拉强度。抗压强度和抗拉强度最适宜的加筋率为1.00%,最佳棕榈长度为4 mm,最优长宽比为1∶3。相对于素土,加筋对抗拉强度的提高幅度高于抗压强度。同时对棕榈加筋土强度提高的机理进行分析。

  4. Load carrying capacity of shear wall t-connections reinforced with high strength wire ropes

    Jørgensen, Henrik B.; Bryndom, Thor; Larsen, Michael


    Traditionally, U-bar loop connections with keyed joints have been used in vertical shear connections between precast concrete wall elements. However, in the recent years, connections with looped high strength wire ropes instead of U-bar loops have proven to be a much more construction......-friendly solution. The wire ropes have no bending stiffness and therefore allow for an easier vertical installation of the wall elements. During the last 10 – 15 years, a number of shear tests on plane wire rope connections have been carried out. However, to the best knowledge of the authors, tests on wire rope...... connections for assembly of precast elements in different planes, such as T- and L-connections, have not yet been published. This paper presents the results of a large test series recently conducted at the University of Southern Denmark to study the shear behaviour of high strength wire rope T...

  5. Load Carrying Capacity of Shear Wall T-Connections Reinforced with High Strength Wire Ropes

    Jørgensen, Henrik Brøner; Bryndum, Thor; Larsen, Michael


    Traditionally, U-bar loop connections with keyed joints have been used in vertical shear connections between precast concrete wall elements. However, in the recent years, connections with looped high strength wire ropes instead of U-bar loops have proven to be a much more construction......-friendly solution. The wire ropes have no bending stiffness and therefore allow for an easier vertical installation of the wall elements. During the last 10 – 15 years, a number of shear tests on plane wire rope connections have been carried out. However, to the best knowledge of the authors, tests on wire rope...... connections for assembly of precast elements in different planes, such as T- and L-connections, have not yet been published. This paper presents the results of a large test series recently conducted at the University of Southern Denmark to study the shear behaviour of high strength wire rope T...

  6. Reinforcement of semicrystalline polymers with collagen-modified single walled carbon nanotubes

    Bhattacharyya, Sanjib; Salvetat, Jean-Paul; Saboungi, Marie-Louise


    We report on the enhancement of the mechanical properties of single wall carbon nanotube (SWNT)-polyvinyl alcohol (PVA) composites through functionalization of SWNTs with denatured collagen. In addition to improving compatibility with the matrix, the denatured collagen layer was found to increase the PVA matrix crystallinity, which results in a dramatic enhancement of the Young's modulus (260%), tensile strength (300%), and toughness (700%) well above what can be expected with the classical rule of mixture. A supramolecular organization at the interface is associated with an increase of PVA crystallinity as shown by the x-ray diffraction and differential scanning calorimetry.

  7. Evolution of the Stability Work from Classic Retaining Walls to Mechanically Stabilized Earth Walls

    Anghel Stanciu


    Full Text Available For the consolidation of soil mass and the construction of the stability works for roads infrastructure it was studied the evolution of these kinds of works from classical retaining walls - common concrete retaining walls, to the utilization in our days of the modern and competitive methods - mechanically stabilized earth walls. Like type of execution the variety of the reinforced soil is given by the utilization of different types of reinforcing inclusions (steel strips, geosynthetics, geogrids or facing (precast concrete panels, dry cast modular blocks, metal sheets and plates, gabions, and wrapped sheets of geosynthetics.

  8. Structure-property relationship in polyethylene reinforced by polyethylene-grafted multi-walled carbon nanotubes.

    Causin, Valerio; Yang, Bing-Xing; Marega, Carla; Goh, Suat Hong; Marigo, Antonio


    Polyethylene-grafted multiwalled carbon nanotubes (PE-g-MWNT) were used to reinforce polyethylene (PE). The nanocomposites possessed not only improved stiffness and strength, but also increased ductility and toughness. The effects on the structure and morphology of composites due to pristine multiwalled carbon nanotubes (MWNT) and PE-g-MWNT were studied and compared using small angle X-ray scattering (SAXS), wide angle X-ray diffraction (WAXD) and differential scanning calorimetry (DSC). The SAXS long period, crystalline layer thickness and crystallinity of polymer lamellar stacks were found to decrease significantly in MWNT composites, while the decreases were much smaller in PE-g-MWNT composites. PE-g-MWNT allowed a more efficient and unhindered crystallization at a lamellar level, while MWNT disrupted the order of lamellar stacks, probably because of their tendency to aggregate. The SAXS crystallinity and the mechanical properties of the composites showed similar trends as a function of MWNT content. This suggested that the improvement of the interfacial strength between polymer and carbon nanotubes was a result of synergistic effects of better dispersion of the filler, better stress transfer, due to the grafting of polymer and MWNT, and the nucleation of a crystalline phase around MWNT. The latter effect was confirmed by measurements of kinetics of non-isothermal crystallization.

  9. Development of multi-walled carbon nanotubes reinforced monetite bionanocomposite cements for orthopedic applications.

    Boroujeni, Nariman Mansoori; Zhou, Huan; Luchini, Timothy J F; Bhaduri, Sarit B


    In this study, we present results of our research on biodegradable monetite (DCPA, CaHPO4) cement with surface-modified multi-walled carbon nanotubes (mMWCNTs) as potential bone defect repair material. The cement pastes showed desirable handling properties and possessed a suitable setting time for use in surgical setting. The incorporation of mMWCNTs shortened the setting time of DCPA and increased the compressive strength of DCPA cement from 11.09±1.85 MPa to 21.56±2.47 MPa. The cytocompatibility of the materials was investigated in vitro using the preosteoblast cell line MC3T3-E1. An increase of cell numbers was observed on both DCPA and DCPA-mMWCNTs. Scanning electron microscopy (SEM) results also revealed an obvious cell growth on the surface of the cements. Based on these results, DCPA-mMWCNTs composite cements can be considered as potential bone defect repair materials.

  10. Effective measures for insulating, packing and reinforcing walls of mine workings

    Postawa, J. [Akademia Gorniczo-Hutnicza, Cracow (Poland). Instytut Gornictwa Podziemnego i Bezpieczenstwa Pracy


    Discusses selected aspects of rock strata bonding used in underground black coal mines in Poland. The following types of acrylic resins are comparatively evaluated: SOLAKRYL M, SOLAKRYL ASM-10, SOLAKRYL SW, SORAKRYL SW-P. Their composition, chemical and physical properties are discussed. Composition of other conventional mixtures used for water influx control (grouting) and filling voids with expansive materials on a fly ash basis are evaluated. Use of acrylic resins for rock strata bonding, sealing porous sedimentary rocks and preventing quicksand intrusions is described. Use of resin injection and grouting in the following black coal mines is evaluated: the Jaworzno mine (water influx control), the Jan Kanty mine (sealing walls of a mine roadway and control of carbon dioxide emission), the Miechowice mine (sealing tubbings in a mine shaft), the Kazimierz Juliusz mine (repair of ventilation barriers).

  11. Measurement of interfacial shear strength in single wall carbon nanotubes reinforced composite using Raman spectroscopy

    Roy, Debdulal; Bhattacharyya, Sanjib; Rachamim, A.; Plati, A.; Saboungi, Marie-Louise


    A novel method of measuring interfacial shear strength using Raman peak shift is reported. Carbon nanotubes (CNT) functionalized with biomolecules have been used to form a composite with polyvinyl alcohol. Type I collagen has proven to improve the load transfer from the matrix to the tubes leading to improvement of interfacial shear strength. Collagen interacts with single wall CNTs and probably wraps around it. When a composite structure is formed with the collagen, load transfer takes place through the collagen molecule. The interfacial strength of the nanotubes-matrix interface was found to be larger than 160 MPa, which is significantly higher than that observed before. A similar shear strength is estimated using a simple analytical calculation.




    Full Text Available The most significant factor that influencing the design thickness of a flexible pavement overlay is rebound deformation from repeated load application and subgrade support values . It is essential to stabilize and reinforce the poor soils to bear the traffic intensity or truck loading. Different types of materials are provided with stabilization techniques to achieve suitable performance and to reduce maintenance costs and also to provide required service life for the subgrade embankments. In the present study, the effect of geo-textile as a reinforcement in the sub grade embankment is verified by conducting cyclic plate load tests. Locally available soil is mixed with optimum of fly ash and then this mixer is stabilized with optimum of CaCl2 for the construction of sub grade embankment with and with out reinforcement. Compaction properties and C.B.R values are determined for the locally available soil and categorized as CH soil as per IS classification, fly ash, fly ash - CaCl2 mix with the CH soil. The introduction of geo-textile has been reduced the deformation and increased the load carrying capacity as was revealed by cyclic plate load tests.

  13. Multi-walled carbon nanotube-reinforced porous iron oxide as a superior anode material for lithium ion battery

    Pang, Xin-Jing; Zhang, Juan; Qi, Gong-Wei; Dai, Xiao-Hui; Zhou, Jun-Ping [School of Chemistry and Chemical Engineering, Shandong University, No. 27, Shanda Nan Rd., Jinan 250100 (China); Zhang, Shu-Yong, E-mail: [School of Chemistry and Chemical Engineering, Shandong University, No. 27, Shanda Nan Rd., Jinan 250100 (China); National Key Lab of Crystal, Shandong University, No. 27, Shanda Nan Rd., Jinan 250100 (China)


    Highlights: • Electrochemical performance of Fe{sub 3}O{sub 4} is improved by combining different approaches. • Porous Cu substrate is used to enlarge surface area and improve conductivity. • MWCNT is used to reinforce the electrode structure and change morphology of Fe{sub 3}O{sub 4}. • Reversible capacity, capacity retention and high-rate performance are improved. - Abstract: Multi-walled carbon nanotube-reinforced porous iron oxide (Fe{sub 3}O{sub 4}/MWCNT) is synthesized by a two-step approach with porous Cu substrate serving as current collector. Porous Cu substrate is prepared through electroless deposition with hydrogen bubble serving as template. Fe{sub 3}O{sub 4}/MWCNT composites are prepared by the electrodeposition of Fe{sub 3}O{sub 4} in the presence of dispersed MWCNTs from a Fe{sub 2}(SO{sub 4}){sub 3} solution with MWCNT suspension. Results showed that Fe{sub 3}O{sub 4} forms granular nanoparticles on the porous Cu substrate with several MWCNTs embedded in it. Adding MWCNTs changes the morphology of Fe{sub 3}O{sub 4}. Smooth Fe{sub 3}O{sub 4}, smooth Fe{sub 3}O{sub 4}/MWCNT, and porous Fe{sub 3}O{sub 4} composites are also prepared for comparison. When used as anode materials, porous Fe{sub 3}O{sub 4}/MWCNT composites have a reversible capacity of approximately 601 mA h g{sup −1} at the 60th cycle at a cycling rate of 100 mA g{sup −1}. This value is higher than that of the other materials. The reversible capacity at a cycling rate of 10,000 mA g{sup −1} is approximately 50% of that at 100 mA g{sup −1}. Therefore, the MWCNT-reinforced porous Fe{sub 3}O{sub 4} composite exhibits much better reversible capacity, capacity retention, and high-rate performance than the other samples. This finding can be ascribed to the porous structure of Fe{sub 3}O{sub 4}, better conductivity of porous Cu substrate and MWCNTs, and the morphology change of Fe{sub 3}O{sub 4} nanoparticles upon the addition of MWCNTs.

  14. Study on Shearing Strength of Typical Reinforced Rammed Earth Wall in Gansu Province%甘肃典型夯土民房承重墙体加固试验研究

    徐舜华; 王兰民; 王强; 袁中夏


    武都是甘肃省典型夯土民房使用地区,研究其夯土民房的抗震性能对于防灾减灾具有重要意义.在试验中,使用武都当地常用土料,完全按照其施工工艺夯筑4片夯土墙体试件,利用伪静力方法研究了素土墙体与使用铁丝网加固墙体的抗剪强度.结果显示:①在竖向荷载10 kN条件下,加固墙体试件较素土墙体试件的水平开裂荷载和极限荷载分别增长了73%和38%,在竖向荷载18 kN条件下,加固墙体试件素土墙体试件的水平开裂荷载和极限荷载分别增长了76%和5%;②随着竖向荷载从10 kN增加到18 kN,素土墙体试件的水平开裂荷载与极限荷载分别增长了217%和359%,加固墙体试件的水平开裂荷载与极限荷载则增长了223%和249%;③在水平往复荷载的作用下,夯土墙体始终沿着夯土层间的水平和垂直接触裂缝产生破坏,最终碎裂成块体.%Research on seismic performance of typical rammed earth houses is important for disaster prevention and mitigation in Wudu, Gansu province. Four experimental walls are built using local material and local construction technology. The shearing strength of raw soil wall and the wall reinforced by iron mesh are investegated by pseudo-static test, the results show, (1) the horizontal crack load and ultimate load of reinforced walls increases by 73% and 38% than those of raw soil walls under the overlying load of 10kN, and those are 76% and 5% under the overlying load 18kN; (2) the crack load and ultimate load of raw soil wall increases by 217% and 359% with the overlying load increases from 10kN to 18kN, while the growth rates are 223% and 249% separately for reinforced wall; (3) the rammed earth wall always destroys along the horizontal and vertical cracks between layers, and eventually breaks into blocks under horizontal cyclic loading.

  15. Development of multi-walled carbon nanotubes reinforced monetite bionanocomposite cements for orthopedic applications

    Boroujeni, Nariman Mansoori [Department of Mechanical, Industrial and Manufacturing Engineering, The University of Toledo, Toledo, OH (United States); Zhou, Huan, E-mail: [Department of Mechanical, Industrial and Manufacturing Engineering, The University of Toledo, Toledo, OH (United States); Luchini, Timothy J.F. [Department of Mechanical, Industrial and Manufacturing Engineering, The University of Toledo, Toledo, OH (United States); Bhaduri, Sarit B. [Department of Mechanical, Industrial and Manufacturing Engineering, The University of Toledo, Toledo, OH (United States); Division of Dentistry, The University of Toledo, Toledo, OH (United States)


    In this study, we present results of our research on biodegradable monetite (DCPA, CaHPO{sub 4}) cement with surface-modified multi-walled carbon nanotubes (mMWCNTs) as potential bone defect repair material. The cement pastes showed desirable handling properties and possessed a suitable setting time for use in surgical setting. The incorporation of mMWCNTs shortened the setting time of DCPA and increased the compressive strength of DCPA cement from 11.09 ± 1.85 MPa to 21.56 ± 2.47 MPa. The cytocompatibility of the materials was investigated in vitro using the preosteoblast cell line MC3T3-E1. An increase of cell numbers was observed on both DCPA and DCPA-mMWCNTs. Scanning electron microscopy (SEM) results also revealed an obvious cell growth on the surface of the cements. Based on these results, DCPA-mMWCNTs composite cements can be considered as potential bone defect repair materials. - Highlights: • A monetite bone cement for orthopedic applications is reported. • Incorporation of MWCNTs into monetite bone cement is discussed. • Surface functionalized MWCNTs can improve the mechanical strength of monetite cement. • MWCNTs have no impacts on the cytocompatibility of monetite cements.


    Amit Srivastava


    Full Text Available The evaluation and design of coastal shore protection works for tsunamis assumed considerable importance following the impact of the 26th December 2004 tsunami in India and other countries of Asia. The lack of proper guidelines made matters worse and resulted in the great damage that occurred. Subsequent surveys indicated that scour resulting from high water velocities was one of the prime reasons in the damage of simple structures. In some cases, it became apparent that sea walls were helpful in minimizing the degree of damage. The objective of the present study is to illustrate how proper design analysis for expected wave heights as well as the use of flexible systems such as geocells, are likely to provide better shoreline protection. Protective systems can be designed that can withstand wave forces that correspond to a variety of incidence probabilities. The present study illustrates such an analytical design approach that is necessary for a shoreline protection system and provides references to relevant wave height data for the east coast of India.

  17. Static analysis of reinforced thin-walled plates and shells by means of finite element models

    Carrera, E.; Zappino, E.; Cavallo, T.


    In this paper, variable kinematic one-dimensional (1D) structural models have been used to analyze thin-walled structures with longitudinal stiffeners and static loads. These theories have hierarchical features and are based on the Carrera Unified Formulation (CUF). CUF describes the displacement field of a slender structure as the product of two function expansions, one over the cross-sectional coordinates, Taylor (TE) or Lagrange (LE) expansions were used here, and one along the beam axis. The results obtained using the refined 1D models have been compared with those from classical finite element analyses that make use of plates/shells and solids elements. The performances of classical and refined structural models have been compared in terms of accuracy and computational costs. The results show that the use of the LE over the cross-section allows the strain/stress fields to be evaluated accurately for all the structural components. The comparisons with the results obtained using the classical models highlight how, the use of 1D refined models, allows the number of degrees of freedom (DOF) to be reduced, meanwhile, the accuracy of the results can be preserved.

  18. Response of soil microorganisms to As-produced and functionalized single-wall carbon nanotubes (SWNTs).

    Tong, Zhonghua; Bischoff, Marianne; Nies, Loring F; Myer, Phillip; Applegate, Bruce; Turco, Ronald F


    The use of single-wall carbon nanotubes (SWNTs) in manufacturing and biomedical applications is increasing at a rapid rate; however data on the effects of a potential environmental release of the materials remain sparse. In this study, soils with either low or high organic matter contents as well as pure cultures of E. coli are challenged with either raw as-produced SWNTs (AP-SWNTs) or SWNTs functionalized with either polyethyleneglycol (PEG-SWNTs) or m-polyaminobenzene sulfonic acid (PABS-SWNTs). To mimic chronic exposure, the soil systems were challenged weekly for six weeks; microbial activities and community structures for both the prokaryote and eukaryote community were evaluated. Results show that repeated applications of AP-SWNTs can affect microbial community structures and induce minor changes in soil metabolic activity in the low organic matter systems. Toxicity of the three types of SWNTs was also assessed in liquid cultures using a bioluminescent E. coli-O157:H7 strain. Although decreases in light were detected in all treated samples, low light recovery following glucose addition in AP-SWNTs treatment and light absorption property of SWNTs particles suggest that AP-SWNTs suppressed metabolic activity of the E. coli, whereas the two functionalized SWNTs are less toxic. The metals released from the raw forms of SWNTs would not play a role in the effects seen in soil or the pure culture. We suggest that sorption to soil organic matter plays a controlling role in the soil microbiological responses to these nanomaterials.

  19. Jet grouting for a groundwater cutoff wall in difficult glacial soil deposits

    Flanagan, R.F.; Pepe, F. Jr. [Parsons Brinckerhoff Quade & Douglas, New York, NY (United States)


    Jet grouting is being used as part of a groundwater cutoff wall system in a major New York City subway construction project to limit drawdowns in an adjacent PCB contamination plume. A circular test shaft of jet grout columns was conducted during the design phase to obtain wall installation parameters. The test program also included shaft wall mapping, and measurements of; inflows, piezometric levels, ground heave and temperature, and jet grout hydraulic conductivity. An axisymmetric finite element method groundwater model was established to back calculate the in-situ hydraulic conductivities of both the surrounding glacial soils and the jet grout walls by matching observed inflows and piezometric levels. The model also verified the use of packer permeability test as a tool in the field to evaluate the hydraulic conductivities of jet grout columns. Both the test program and analytic studies indicated that adjustments to the construction procedures would be required to obtain lower hydraulic conductivities of the jet grout walls for construction. A comparison is made with the conductivities estimated from the test program/analytic studies with those from the present construction.

  20. Uptake of gaseous formaldehyde onto soil surfaces: a coated-wall flow tube study

    Li, Guo; Su, Hang; Li, Xin; Meusel, Hannah; Kuhn, Uwe; Pöschl, Ulrich; Shao, Min; Cheng, Yafang


    Gaseous formaldehyde (HCHO) is an important intermediate molecule and source of HO2 radicals. However, discrepancies exist between model simulated and observed HCHO concentrations, suggesting missing sources or sinks in the HCHO budget. Multiphase processes on the surface of soil and airborne soil-derived particles have been suggested as an important mechanism for the production/removal of atmospheric trace gases and aerosols. In this work, the uptake of gaseous HCHO on soil surfaces were investigated through coated-wall flow tube experiments with HCHO concentration ranging from 10 to 40 ppbv. The results show that the adsorption of HCHO occurred on soil surfaces, and the uptake coefficient dropped gradually (i.e., by a factor of 5 after 1 hour) as the reactive surface sites were consumed. The HCHO uptake coefficient was found to be affected by the relative humidity (RH), decreasing from (2.4 ± 0.5) × 10-4 at 0% RH to (3.0 ± 0.08) × 10-5 at 70% RH, due to competition of water molecule absorption on the soil surface. A release of HCHO from reacted soil was also detected by applying zero air, suggesting the nature of reversible physical absorption and the existence of an equilibrium at the soil-gas interface. It implies that soil could be either a source or a sink for HCHO, depending on the ambient HCHO concentration. We also develop a Matlab program to calculate the uptake coefficient under laminar flow conditions based on the Cooney-Kim-Davis method.

  1. An evaluation of the impact of multi-walled carbon nanotubes on soil microbial community structure and functional diversity

    Increasing application of carbon nanotubes (CNTs) triggers the need for an assessment of their effects on organisms in the environment. Soil microbial communities play a significant role in soil organic matter dynamics and nutrient cycling. This study evaluated the impacts of multi-walled carbon nan...

  2. Experimental study on interaction mechanism of small H-beams and a soil-cement retaining wall

    WANG Suo-rong; CAO Bao-fei


    Small H-beams such as the No.14-20 I-steel can be inserted into soil-cement retaining walls to form small H-beam soil-cement compound walls, functioning both as a retaining wall and a cutoff wall for braced structure excavations. Being different from the mixed soil-cement wall (SMW), the interaction between soil-cement and small H-steel is very good. We have carried out a series of bending experiments on small H-beams in soil-cement model compound beams to study the mechanism of interactions. The results show that the interaction between H-beams and soil-cement is very good, whether the H-beam is single or double. Joint forms of double H-beams at one end have little effect on both the contribution coefficient and on ultimate deflection before crack-ing. But after cracking, the joint forms greatly affect the contribution coefficient. We conclude that the rigid joint girder for double H-beams is a better choice in practice.

  3. A coupled soil-fluid-structure simulation of the near-field earthquake effects on gravity type quay-walls

    Zeinoddini, M.; Matin Nikoo, H.; Ahmadpour, F.


    This study focuses on non-linear seismic response of concrete gravity quay-wall structures subjected to near-fault ground motions, a subject which seems not to have received much attention in the literature. A two-dimensional coupled fluid-structure-soil finite element modelling is employed to obtain the quay-wall response. The seawater medium is represented by acoustic type, potential based fluid elements. The elasto-plastic behavior of the soil medium is idealized using Drucker-Prager yield criterion based on associated flow rule assumption. Four nodded plane strain elements are used to model the concrete wall, foundation, subsoil, backfill and seabed zones. Fluid Structure Interface (FSI) elements are considered between the seawater interfaces with the quay-wall and the seabed. Frictional contact elements are employed between the wall and soil interfaces. The numerical model is validated using field measurements available for permanent drifts in a quay-wall damaged during Kobe earthquake. Reasonable agreements are obtained between the model predictions and the field measurements. Non-linear seismic analyses of the selected quay-wall subjected to both near-fault and far-fault ground motions are performed. An incremental dynamic analysis approach (IDA) is used. In general, at least for models examined in the current study, the gravity quay-walls are found to be more vulnerable to near-field, in comparison with the corresponding far-field, earthquakes.

  4. Seismic Performance of Precast Reinforced Concrete Core Wall with Horizontal Tied Rebars at Mid Height Level of First Story

    Nakachi, Tadaharu


    Precast core walls are considered effective for construction because they can be built more quickly than cast-in-place core walls. Previously, we conducted a lateral loading test on a full precast wall column simulating the area near the corner of an L-shaped core wall in order to examine the seismic performance. The wall column was divided into precast columns, and horizontal tied rebars were concentrated at the second and third floor levels to connect the precast columns. In this study, a l...

  5. 三洋港枢纽工程钢筋混凝土地下连续墙施工%Reinforced concrete diaphragm wall construction of Three Ocean Port hub project

    孟仁富; 秦立建; 邱雪峰


    Introdcuing reinforced concrete diaphragm wall construction technology of Three Ocean Port hub project, New Shuhe treatment project under coastal complicated geological conditions, and elaborating the key process quality control measurement. The practice has proved that rein- forced concrete diaphragm wall construction technology which used by the project is suited for large range of coastal groundwater and complicated conditions of soil. Meanwhile, this kind of techonology can be used to maintain the stability of surface mining effectively, provide a reference for those similar construction projects.%介绍了新沭河治理工程三洋港枢纽工程沿海复杂地质条件下钢筋混凝土地下连续墙施工技术,并详细阐述了其关键工序质量控制措施,实践证明本工程采用钢筋混凝土地连墙施工工艺适用于沿海地下水变化范围大、土质复杂条件,同时可有效地保持挖掘面的稳定,可为类似工程施工提供借鉴。

  6. 以强度增长率评价麦秸秆加筋盐渍土的加筋效果%Examination of reinforcement effect on basis of strength increment of reinforced saline soil with wheat straw and lime

    李敏; 柴寿喜; 王晓燕; 魏丽


    Inferior strength, which is caused by salt expansion, dissolution and water absarption of inshore saline soil, will be prevented with the help of reinforcement with wheat straw and lime.First.some samples are prepared.which including saline soil,reinforced saline soil with wheat straw, lime-saline soil.and reinforced saline soil with lime and wheat straw as the way of reinforcement in whole, upper and lower position respectively.Then.unconfined compressive strength tests of 50 mm 152 mm (heavy compaaion specimen) and 102 mm (lightly compaction specimen), as well as triaxial shear test of 61.8 mm in diameter are carried out.Finally.strength increment ratio of deviator stress, and cohesion increment are defined to evaluate the reinforcement effect.The results show that: 1, Reinforcement raise the strength and the anti-deformation of soil.2.Reinforced action increase largely the cohesion of soil and the reinforcement in lower position can contribute a more effective role.3.Strength of reinforced soil is contributed mostly by wheat straw and lime; the strength in water depends on chemical reaction of lime.4.Lateral deformation of reinforced soil is restricted by means of wheat straw within a lower confining pressure, and that is supported jointly by reinforcement and confining pressure within a higher confining pressure.Reinforcement with wheat straw is one of the suitable means for improving strength and anti-deformation of inshore saline soil.%采用麦秸秆与石灰共同加筋固化滨海盐渍土,可解决由于盐胀、溶陷和吸湿软化引起的土体强度下降问题.首先,制备盐渍土、石灰土、麦秸秆加筋盐渍土和麦秸秆加筋石灰土试样(整体均匀加筋、上部均匀加筋和下部均匀加筋);进而,进行φ50 mm试样、φ152 mm重型击实试样和φ102 mm轻型击实试样的无侧限抗压强度试验,以及φ61.8 mm试样三轴压缩试验;最后,分析抗压强度增长率、主应力差比值和黏聚力增长率的变

  7. Kevlar and Carbon Fiber Sheet Reinforced Soil Reinforced Concrete Beam Flexural Performance Test Inquiry%碳纤维布及芳纶布加固钢筋混土梁受弯性能试验探究



    在土木工程建设中,碳纤维布及芳纶布为钢筋混土构件带来了新的加固机遇,已成为工程施工中的实质性保障,占据着综合比例的重要地位。基于此,从钢筋混土梁入手,结合相关试验案例,重点分析碳纤维布及芳纶布加固钢筋混土梁受弯性能的优化举措,以供相关研究参考。%In the civil engineering construction,carbon fiber and Kevlar fiber cloth cloth reinforced concrete soil reinforcement member has brought new opportunities,construction has become a substantive guarantee,occupies an important position integrated scale.Based on this,the soil from reinforced concrete beams,combining relevant test case focuses on Kevlar Reinforced with carbon fiber sheet reinforced concrete and soil beam flexural performance optimization initiatives for research reference.

  8. wall

    Irshad Kashif


    Full Text Available Maintaining indoor climatic conditions of buildings compatible with the occupant comfort by consuming minimum energy, especially in a tropical climate becomes a challenging problem for researchers. This paper aims to investigate this problem by evaluating the effect of different kind of Photovoltaic Trombe wall system (PV-TW on thermal comfort, energy consumption and CO2 emission. A detailed simulation model of a single room building integrated with PV-TW was modelled using TRNSYS software. Results show that 14-35% PMV index and 26-38% PPD index reduces as system shifted from SPV-TW to DGPV-TW as compared to normal buildings. Thermal comfort indexes (PMV and PPD lie in the recommended range of ASHARE for both DPV-TW and DGPV-TW except for the few months when RH%, solar radiation intensity and ambient temperature were high. Moreover PVTW system significantly reduces energy consumption and CO2 emission of the building and also 2-4.8 °C of temperature differences between indoor and outdoor climate of building was examined.

  9. Research on Stress and Strength of High Strength Reinforced Concrete Drilling Shaft Lining in Thick Top Soils

    YAO Zhi-shu; CHANG Hua; RONG Chuan-xin


    High strength reinforced concrete drilling shaft linings have been adopted to solve the difficult problem of supporting coal drilling shafts penetrating through thick top soils. Through model experiments the stress and strength of such shaft linings are studied. The test results indicate that the load bearing capacity of the shaft lining is very high and that the main factors affecting the load bearing capacity are the concrete strength, the ratio of lining thickness to inner radius and the reinforcement ratio. Based on the limit equilibrium conditions and the strength theory of concrete under multi-axial compressive stressed state, a formula for calculating the load-bearing capacity of a high strength reinforced concrete shaft lining was obtained. Because the concrete in a shaft lining is in a multi-axial compressive stress state the compressive strength increases to a great extent compared to uni-axial loading. Based on experiment a formula for the gain factor in compressive strength was obtained: it can be used in the structural design of the shaft lining. These results have provided a basis for sound engineering practice when designing this kind of shaft lining structure.

  10. Effect of Geotextile Reinforcement on Shear Strength of Sandy Soil: Laboratory Study

    Denine, Sidali; Della, Noureddine; Dlawar, Muhammed Rawaz; Sadok, Feia; Canou, Jean; Dupla, Jean-Claude


    This paper presents results of a series of undrained monotonic compression tests on loose sand reinforced with geotextile mainly to study the effect of confining stress on the mechanical behaviour of geotextile reinforced sand. The triaxial tests were performed on reconstituted specimens of dry natural sand prepared at loose relative density (Dr = 30%) with and without geotextile layers and consolidated to three levels of confining pressures 50, 100 and 200 kPa, where different numbers and different arrangements of reinforcement layers were placed at different heights of the specimens (0, 1 and 2 layers). The behaviour of test specimens was presented and discussed. Test results showed that geotextile inclusion improves the mechanical behaviour of sand, a significant increase in the shear strength and cohesion value is obtained by adding up layers of reinforcement. Also, the results indicate that the strength ratio is more pronounced for samples which were subjected to low value of confining pressure. The obtained results reveal that high value of confining pressure can restrict the sand shear dilatancy and the more effect of reinforcement efficiently.

  11. Effect of Specimen Size on the Tensile Strength Behavior of the Plastic Waste Fiber Reinforced Soil – Lime – Rice Husk Ash Mixtures

    Muntohar A.S.


    Full Text Available Improvement of tensile strength in fiber reinforced soil is an important research topic. A study has been undertaken to investigate the strength of stabilized clay-soil reinforced with randomly distributed discrete plastic waste fibers by carrying out split tensile strength test. In this study, the clay soil was stabilized with lime and rice husk ash mixtures. The main purpose of this research is to investigate the effect of specimen size to the tensile strength behavior. Testing procedure was formulated using extended ASTM C496 standard. The laboratory investigation results showed that split-tensile strength of reinforced specimens increased with increase in size. The limitations of the dataset indicate that specimen size of 70 mm in diameter is the threshold to produce reasonable representative strengths.

  12. 西夏陵夯补支顶加固工艺质量控制研究%Quality Control Research on Reinforcement Technology Tests Using Rammed Earth to Fill Unsupported Walls in a Western Xia Imperial Tomb

    张博; 王旭东; 郭青林; 裴强强; 杨善龙; 李凤洁


    土坯砌补与夯补支顶是西北干旱环境下加固土遗址悬空区常用的两种技术措施,对于夯筑类土遗址而言,夯补相较于砌补有明显的优势,既能保持遗址本体的原有工艺,避免土坯砌补表面处理层脱落露出砌补层影响观感,同时夯补体本身具有较强的稳定性和较强的抗风蚀、雨蚀能力。但是不同遗址夯土的建筑工艺、土的物理力学性质不同,施工过程中夯补质量无法准确控制。本文针对西夏陵遗址本体根部夯筑砌补,采用与原遗址相近的当地土,以固定质量夯锤为夯筑工具、并以传统人工夯实方法进行夯筑,分析研究夯土密度随铺土厚度和夯筑次数的变化规律,探索最佳铺土厚度和夯筑次数。试验结果表明,当使用2kg夯锤进行夯筑时,铺土厚度为12cm,垂直夯筑4次,即可得到密度较大且密度均匀的最佳夯筑效果。%There are two construction techniques frequently used in reinforcing unsupported regions of earthen structures in arid areas of northwest China:using adobe brick as a masonry complement, and filling the unsupported wall with rammed earth. For archaeological sites made of rammed earth, using soil to fill the top of a structure is better than using adobe brick because this technique is adopted from the original technology of the region and does not affect the physical appearance of the building. In addition, the rammed earth itself has strong stability and resistance to erosion caused by wind and rain. However, the quality of rammed earth cannot be controlled in the construction process precisely due to the different building techniques of the sites and the dif-ferent physical and mechanical properties of the soil. Focusing on the reinforcement of the foot of a wall of a Western Xia imperial tomb with rammed earth, this study utilizes local soil with the same properties of that used at the time, a pounding tool of fixed mass, and the

  13. Spark plasma sintering of silicon carbide, multi-walled carbon nanotube and graphene reinforced zirconium diboride ceramic composite

    Balaraman Yadhukulakrishnan, Govindaraajan

    Scope and Method of Study: Space vehicles re-entering the earth's atmosphere experience very high temperatures due to aerodynamic heating. Ultra-high temperature ceramics (UHTC) with melting point higher than 3200°C are promising materials for thermal protection systems of such space vehicles re-entering the earth's atmosphere. Among several UHTC systems ZrB2 based ceramic composites are particularly important for thermal protection systems due to their better mechanical and thermoelectric properties and high oxidation resistance. In this study spark plasma sintering of SiC, carbon nanotubes (CNT) and graphene nano platelets (GNP) reinforced ZrB2 ultra-high temperature ceramic matrix composites is reported. Findings and Conclusions: Systematic investigations on the effect of reinforcement type (SiC, CNTs and GNP) and content (10-40 vol.% SiC, 2-6 vol.% CNTs and 2-6 vol.% GNP) on densification behavior, microstructure development, and mechanical properties (microhardness, bi-axial flexural strength, and indentation fracture toughness) are reported. With the similar SPS parameters near-full densification (>99% relative density) was achieved with 10-40 vol.% SiC, 4-6 vol.% CNT reinforced composites. Highly dense composites were obtained in 4-6 vol.% GNP reinforced composites. The SiC, CNT and GNP reinforcement improved the indentation fracture toughness of the composites through a range of toughening mechanisms, including particle shearing, crack deflection at the particle-matrix interface, and grain pull-outs for ZrB2-SiC composites, CNT pull-outs and crack deflection in ZrB2-CNT composites and crack deflection, crack bridging and GNP sheet pull-out for ZrB2 -GNP composites.

  14. Research on the thermal performances of reinforced concrete sandwich wall-panel%混凝土夹芯复合墙板热工性能研究

    蒋金梁; 干钢


    结合浙江省等夏热冬冷地区的节能设计标准,研究开发了一种自保温混凝土夹芯复合墙板,并重点研究了混凝土夹芯复合墙板在不同保温层厚度、斜向钢筋含量和混凝土层厚度情况下,其热工性能指标的变化规律.结果表明,在不采取额外保温措施的情况下,混凝土夹芯复合墙板的热工性能能满足夏热冬冷地区节能设计标准要求.研究成果与实际工程联系紧密,具有较高的实用价值.%In combination with the standard of energy conservation in the Hot Summer and Cold Winter Regiona like Zhejiang Province,a kind of aelf-insulation reinforced concrete sandwich wall-panel is exploited Influence on thermal performances of reinforce concrete sandwich wall-panel,due to the difference in thickness of concrete layer,the thickness of heat insulation layer and the ratio of oblique tie bar,are analyzed. The investigation reveals that under the condition of not taking additional thermal insulation measures the thermal performances of concrete wall-panel meet the requirements of standard of energy conservation in the Hot Summer and Cold Winter Regions. The findings of this paper are tightly related to the engineering practice and have relatively higher use value

  15. Critical embedment depth of a rigid retaining wall against overturning in unsaturated soils considering intermediate principal stress and strength nonlinearity

    张常光; 陈新栋; 范文


    The overturning stability is vital for the retaining wall design of foundation pits, where the surrounding soils are usually unsaturated due to water draining. Moreover, the intermediate principal stress does affect the unsaturated soil strength; meanwhile, the relationship between the unsaturated soil strength and matric suction is nonlinear. This work is to present closed-form equations of critical embedment depth for a rigid retaining wall against overturning by means of moment equilibrium. Matric suction is considered to be distributed uniformly and linearly with depth. The unified shear strength formulation for unsaturated soils under the plane strain condition is adopted to characterize the intermediate principal stress effect, and strength nonlinearity is described by a hyperbolic model of suction angle. The result obtained is orderly series solutions rather than one specific answer; thus, it has wide theoretical significance and good applicability. The validity of this present work is demonstrated by comparing it with a lower bound solution. The traditional overturning designs for rigid retaining walls, in which the saturated soil mechanics neglecting matric suction or the unsaturated soil mechanics based on the Mohr-Coulomb criterion are employed, are special cases of the proposed result. Parametric studies about the intermediate principal stress, matric suction and its distributions along with two strength nonlinearity methods on a new defined critical buried coefficient are discussed.

  16. Co-transport of chlordecone and sulfadiazine in the presence of functionalized multi-walled carbon nanotubes in soils

    Batch and saturated soil column experiments were conducted to investigate sorption and mobility of two 14C-labeled contaminants, the hydrophobic chlordecone (CLD) and the readily water-soluble sulfadiazine (SDZ), in the absence or presence of functionalized multi-walled carbon nanotubes (MWCNTs). Th...

  17. Rapid analysis of phthalates in beverage and alcoholic samples by multi-walled carbon nanotubes/silica reinforced hollow fibre-solid phase microextraction.

    Li, Jia; Su, Qiong; Li, Ke-Yao; Sun, Chu-Feng; Zhang, Wen-Bo


    A novel procedure based on multi-walled carbon nanotubes (MWCNTs)/silica reinforced hollow fibre solid-phase microextraction combined with gas chromatography-mass spectrometry has been developed to analyse trace phthalate acid esters in beverage and alcoholic samples. Because of their excellent adsorption capability towards hydrophobic compounds, functionalized MWCNTs, acting as solid-phase sorbent, were co-deposited with silica particles in the pores of polypropylene hollow fibre through a layer-by-layer self-assembly technique. The parameters influencing the extraction efficiency, such as pH values and ionic strength of sample solution, extraction time, temperature and desorption solvent were optimised. Recoveries for phthalates at spiking levels in different matrices were satisfactory (between 68% and 115%). Moreover, the results were further confirmed by comparing them with those obtained using a solvent extraction method according to the national standard of China.

  18. Quantitative analysis of biotechnical reinforcement for a steep slope consisting of composite coal-gangue-soil medium adjacent to a mined-out area

    Xingping Lai; Mowen Xie; Fenhua Ren; Meifeng Cai


    The engineering and geological characteristics of a steep slope consisting of coal gangue, rock and soil medium in Huating coal mine have been comprehensively investigated. Owing to humid weather, heavy rainfall, vegetation and porous characteristics of the soil and rock mass, the steep slope will be destabilized and induce mud-rock flow or derive hazard easily. Firstly, based on the classical slope reinforcement theory, some regularity between the shear and displacement in the destabilized zone of the slope with or without root strength contribution is presented. Then, based on the experimental and statistical analysis of root strength, hydrological characteristics and stability status, etc., some possible biotechnical techniques for reinforcement of the steep slope have been suggested. These methods are important for quantitative analysis of destabilization of the slope and design of the biotechnical reinforcement.

  19. Assesment risk of fracture in thin-walled fiber reinforced and regular High Performance Concretes sandwich elements

    Hodicky, Kamil; Hulin, Thomas; Schmidt, Jacob Wittrup


    High Performance Concrete Sandwich Elements (HPCSE) are an interesting option for future low or plus energy building construction. Recent research and development work, however, indicate that such elements are prone to structural cracking due to the combined effect of shrinkage and high temperature...... load. Due to structural restraints, autogenous shrinkage may lead to high self-induced stresses. Therefore autogenous shrinkage plays important role in design of HPCSE. The present paper assesses risk of fracture due to autogenous shrinkage-induced stresses in three fiber reinforced and regular High...


    邹桐; 张孟喜


    According to the experimental data of reinforced retaining wall,the reasonable shape and location of the rupture face of reinforced retaining wall were selected and considering the effect of the uniform load on the rupture face,it was got the formula of the critical length of rigid dental-strip reinforcements used in retaining wall based on the equilibrium method for wedge sliding.The influence of the height of the vertical reinforcing element and that of the vertical spacing of the horizontal reinforcing element on the critical length of the reinforced retaining wall were analyzed.A more effective way of the material used was discussed.%结合带齿筋H-V加筋土挡墙模型试验,在假定加筋土挡墙破裂面的位置及形状的基础上,考虑均布荷载对破裂面的影响,以楔形体的极限平衡理论为基础,推导出在黏着破坏条件下H-V加筋土挡墙筋条临界长度的表达式。探讨齿筋高度以及水平筋间距对挡墙加筋筋条临界长度的影响,提出在相同承载力下更有效的筋材配置方法。结合室内试验,解释H-V加筋土挡墙黏着破坏时的破坏机理。

  1. 加筋土技术的研究现状与展望%Research Status and Prospect of Reinforced Soil Technology



    Reinforced soil technology is widely used in civil engineering, and it is a hot research topic in the field of civil engineering. Through the experimental research of reinforced soil, reinforcement mechanism research, calculation method of the analysis of the present situation, this paper pointed out the characteristics of current research, and aiming at the deficiencies of the reinforcement technology at present, from the problems and the development trend of the current reinforcement, it put forward the future research needs to be discussed further concern.%加筋土技术在土木工程中应用较广,是目前研究的一个热点.通过加筋土实验研究、加筋机理的研究、计算方法的研究等现状分析,指出当前研究的特点,针对加筋技术目前研究的不足之处,从目前加筋的问题和发展的趋势,提出今后研究尚待进一步探讨关注的问题.

  2. Influence of Vehicle Load as Point Load on Geogrid Deformation as Embankment Reinforcement on Soft Soil

    A. Adhe Noor Patria SH


    Full Text Available Public contructions built on soft soil such as clay would face some problems such as long period consolidation time, unstability embankment slope, not easily compacted and high level settlement. Some solution that could be suggested were the usage of vertical drain, or the usage of geosynthetics material such as geogrid combined with floating piles. Analysis was carried out by using plaxis version 7.2. soil for embankment and embankment foundation was modelled in plane strain. Also geogrid and floating piles were modelled in plane strain too. Point load on top of embanknet were variated, they were 20, 40 and 60 kN/m. The simulation was carried out in staged contruction mode. The implementation of vehicle load increased geogrid deformation. It appeared as geogrid vertical displacement when the biggest vehicle load ( 60 kn/m applied. In long term loading condition where excess pore water pressure was very small, vertical displacement of geogrid was – 0,5062 m for rigid embankment and – 0,6568 m for interface embankment. The difference occured due to slip at the interface of geogrid and soil. It leaded to adding soil mass supported by geogrid, furthermore the deflection of geogrid became bigger.

  3. Determination of increase in shear strength of soil reinforced with plant roots

    Sudan Acharya, Madhu; Alvarez Suarez, Sandra Patricia; Rauchecker, Markus


    The stability of a slope depends on the strength of the soil material comprising of the slope, the triggering factors and slope geometry. Vegetation growing on the slope can have mechanical, biological and hydrological roles which influence the strength characteristics of the material on the slope. The mechanical contributions arise from the physical interactions of either the foliage or the root system of the plant with the slope (Gray & Sotir, 1996). The plant roots increase the soil suction reducing pore water pressures, which significantly increases the cohesion (c) and also the friction angle (φ) to some extent. In an experimental investigation carried out in a highway embankment in Germany, an increase of effective cohesion from 1.1 kN/m² to 6.3 kN/m² and friction angle from 33.1° to 34.7° were observed. (Katzenbach & Werner, 2005). Considering the complex nature of influences of plants on slope stability, more field oriented experimental research works on different vegetative systems are required to quantify the role of different plants in slope stability. In the above context, in order to observe the increase in the shear strength of soil by different types of plant roots, an experiment has been carried out at the University of Natural Resources and Life Sciences (BOKU). This experiment consist of 10 wooden boxes of size 50x50x60 cm and 5 boxes of size 50x50x40 cm filled with normal soil suitable for growth of plants. The ten number of bigger size boxes are planted with acer campestre plants. In the other five boxes of smaller size, a mixed seed of 21 different grass species has been sowed. All the boxes are kept in an experimental field and regular take care is being done. The grass will be cut each year and the biomass will be measured. The undisturbed soil samples from each of these boxes in first and second year will be taken to the large frame (50x50cm) direct shear test equipment and tested for direct shear. A comparison of shear strength of soil

  4. 混合土层吹填技术对新吹填土真空预压加固效果的影响%Influence of mixed soil reclamation technology on vacuum preloading reinforcement effect of new reclaimed soil

    董志凌; 曲月华


    At present the reclamation construction is easy to form soft soil layers, which have a negative impact on the new reclaimed soil reinforcement effect. According to the analysis of engineering examples, we proposed that through improving reclamation process, choosing the mixed soil for reclamation, disordering the soil structure, improving the permeability of soil mass to improve the soil reinforcement effect, which can provide a new method for ultra-soft foundation reinforcement engineering.%目前的吹填施工易形成软弱土层,对新吹填土加固效果产生不良影响。根据工程实例分析,提出通过改进吹填工艺,选择混合土层吹填,紊乱土体结构,改善土体的渗透性,达到改善土体加固效果的目的,为超软基加固工程提供新的思路。

  5. Complete Soil-Structure Interaction (SSI) Analyses of I-walls Embedded in Level Ground During Flood Loading


    8217 El=-2.5’ Sheet pile tip ERDC/ITL TR-12-4 10 (CWALSHT) ( Dawkins 1991) and procedures outlined in HQUSACE (1994). The initial design depth of...mechanics. 6th ed. New York: Chapman and Hall. Dawkins , W. P. 1991. User’s guide: Computer program for design and analysis of sheet- pile walls by... Dawkins , R. Mosher, and I. Hallal. 1997. Soil-structure interaction effects in floodwalls. Electronic Journal of Geotechnical Engineering. http

  6. 江苏省新沭河治理三洋港枢纽工程钢筋混凝土地下连续墙施工技术%Construction Technology of Reinforced Concrete Diaphragm Wall in SanYang Port Hub Project,New Shuhe Treatment Project

    颜建; 陆明志; 封荣东; 陆俊华


    介绍新沭河治理工程三洋港枢纽工程沿海复杂地质条件下钢筋混凝土地下连续墙施工技术,并详细阐述其关键工序质量控制措施。实践证明本工程采用钢筋混凝土地连墙施工工艺适用于沿海地下水变化范围大、土质复杂条件,同时可有效地保持挖掘面的稳定,可以为类似工程施工提供借鉴。%Introducing reinforced concrete diaphragm wall construction technology of Sanyang Port Hub Project,New Shuhe Treatment Project under coastal complicated geological conditions,and elaborating the key process quality control measurement.The practice has proved that reinforced concrete diaphragm wall construction technology which used by the project is suited for large range of coastal groundwater and complicated conditions of soil.Meanwhile,this kind of techonology can be used to maintain the stability of surface mining effectively,provide a reference for those similar construction projects.

  7. Out-of-plane (SH) soil-structure interaction: a shear wall with rigid and flexible ring foundation

    Le, Thang; Lee, Vincent W.; Luo, Hao


    Soil-structure interaction (SSI) of a building and shear wall above a foundation in an elastic half-space has long been an important research subject for earthquake engineers and strong-motion seismologists. Numerous papers have been published since the early 1970s; however, very few of these papers have analytic closed-form solutions available. The soil-structure interaction problem is one of the most classic problems connecting the two disciplines of earthquake engineering and civil engineering. The interaction effect represents the mechanism of energy transfer and dissipation among the elements of the dynamic system, namely the soil subgrade, foundation, and superstructure. This interaction effect is important across many structure, foundation, and subgrade types but is most pronounced when a rigid superstructure is founded on a relatively soft lower foundation and subgrade. This effect may only be ignored when the subgrade is much harder than a flexible superstructure: for instance a flexible moment frame superstructure founded on a thin compacted soil layer on top of very stiff bedrock below. This paper will study the interaction effect of the subgrade and the superstructure. The analytical solution of the interaction of a shear wall, flexible-rigid foundation, and an elastic half-space is derived for incident SH waves with various angles of incidence. It found that the flexible ring (soft layer) cannot be used as an isolation mechanism to decouple a superstructure from its substructure resting on a shaking half-space.

  8. Effect of processing parameter and filler content on tensile properties of multi-walled carbon nanotubes reinforced polylactic acid nanocomposite

    Ali, Adilah Mat; Ahmad, Sahrim Hj.


    Polymer nanocomposite of multi-walled carbon nanotubes (MWCNT) nanoparticles incorporated with polylactic acid (PLA) and liquid natural rubber (LNR) as compatibilizer were prepared via melt blending method using the Haake Rheomix internal mixer. In order to obtain the optimal processing parameter, the nanocomposite with 89 wt % of PLA was blended with 10 wt % of LNR and 1 wt % of MWCNTs were mixed with various mixing parameter condition; mixing temperature, mixing speed and mixing time. The optimum processing parameter of the composites was obtained at temperature of 190°C, rotation speed of 90 rpm and mixing time of 14 min. Next, the effect of MWCNTs loading on the tensile properties of nanocomposites was investigated. The nanocomposites were melt blended using the optimal processing parameter with MWCNTs loading of 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5 and 4 wt %. The result showed that the sample with 3.5 wt % of MWCNTs gave higher tensile strength and Young's modulus. The SEM micrographs confirmed the effect of good dispersion of MWCNTs and their interfacial bonding in PLA nanocomposites. However, the elongation at break decreased with increasing the percentage of MWCNTs.

  9. An analytical model for shape memory alloy fiber-reinforced composite thin-walled beam undergoing large deflection

    Yongsheng Ren


    Full Text Available The structural model of the thin-walled laminated beams with integral shape memory alloy active fibers and accounting for geometrically nonlinear is presented in this article. The structural modeling is split into two parts: a two-dimensional analysis over the cross section and a geometrically nonlinear analysis of a beam along the beam span. The variational asymptotic method is used to formulate the force–deformation relationship equations taking into account the presence of active shape memory alloy fibers distributed along the cross section of the beam. The geometrically nonlinear governing equations are derived using variational principle and based on the von Kármán-type nonlinear strain–displacement relations. The equations are then solved using Galerkin’s method and an incremental Newton–Raphson method. The validation for the proposed model has been carried out by comparison of the present results with those available in the literature. The results show that significant extension, bending, and twisting coupled nonlinear deflections occur during the phase transformation due to shape memory alloy actuation. The effects of the volume fraction of the shape memory alloy fiber and ply angle are also addressed.

  10. Shear strength and failure form of lime-soil reinforced with wheat straw%麦秸秆加筋石灰土的抗剪强度及剪切破坏形式

    李敏; 柴寿喜; 杜红普; 魏丽; 石茜


    选取整体均匀布筋、上部均匀布筋和下部均匀布筋3种布筋位置,借助三轴压缩实验,研究布筋位置对麦秸秆加筋石灰土抗剪强度的影响及3种布筋位置加筋土的破坏形式.结果表明,布筋位置主要影响土的黏聚力,对内摩擦角的影响较小,适宜的麦秸秆布筋方式可有效提高土的黏聚力;石灰土呈脆性破坏,3种布筋位置的麦秸秆加筋石灰土的破坏均在未加筋区域产生,加筋部位土的变形较小;石灰土和麦秸秆加筋石灰土的破坏面倾角均符合Mohr-Coulomb破坏准则和SMP(spatial mobilization plane)破坏准则.借助麦秸秆的高抗拉性能、空间交织作用和筋土摩擦作用,可有效约束土的变形,提高土的强度.%The reinforcement effect and strength of reinforced soil depending on a suitable reinforced position and triaxial shear test for reinforced lime-soil with wheat straw in three positions was carried out in this paper. First,reinforced position mainly affects the cohesion of reinforced soil, but has little influence on the internal friction angle; reasonable reinforced position plays an important role in improving strength of reinforced soil. Second, limesoil displays failure in brittle manner; failure of reinforced lime-soil is located in un-reinforced region; the deformation in reinforced region decreases. Third, shear angle of lime-soil and reinforced lime-soil with wheat straw conform to the Mohr-Coulomb failure criterion and SMP (spatial mobilization plane) failure criterion. By the function of high tensile strength, space interweaving and load-sharing of wheat straw, the strength and anti-deformation of reinforced soil is improved.

  11. Roles of cation valance and exchange on the retention and colloid-facilitated transport of functionalized multi-walled carbon nanotubes in a natural soil

    Saturated soil column experiments were conducted to investigate the transport, retention, and release behavior of a low concentration (1 mg L-1) of functionalized 14C-labeled multi-walled carbon nanotubes (MWCNTs) in a natural soil under various solution chemistries. Breakthrough curves (BTCs) for M...

  12. Phytoremediation of cadmium-contaminated soils by young Douglas fir trees: effects of cadmium exposure on cell wall composition.

    Astier, Cédric; Gloaguen, Vincent; Faugeron, Céline


    Douglas fir trees grown on an artificially Cd-contaminated soil, can tolerate this trace element (up to 68 mg/kg in soil) during several months. Most of the absorbed Cd is retained in roots (25 mg/kg DM), but transfer to aerial part is also effective. Showing the highest content, up to 6 mg/kg DM, among all the aboveground parts, barks seem to be a preferred storage compartment. However, the transfer factor is quite low, about 0.3. Another objective of this study was to compare the cell wall components of trees exposed to increasing Cd amounts in soil. A decrease in lignin and an increase in pectin contents were observed in response to increasing soil cadmium concentration. A concurrent reduction in methyl-esterification of pectin suggests than the structure of this major binding site could therefore be modified as a reaction to cadmium contamination. Future prospects will focus on the modulation of pectin composition in response to Cd exposure.

  13. Electrical resisitivity of mechancially stablized earth wall backfill

    Snapp, Michael; Tucker-Kulesza, Stacey; Koehn, Weston


    Mechanically stabilized earth (MSE) retaining walls utilized in transportation projects are typically backfilled with coarse aggregate. One of the current testing procedures to select backfill material for construction of MSE walls is the American Association of State Highway and Transportation Officials standard T 288: ;Standard Method of Test for Determining Minimum Laboratory Soil Resistivity.; T 288 is designed to test a soil sample's electrical resistivity which correlates to its corrosive potential. The test is run on soil material passing the No. 10 sieve and believed to be inappropriate for coarse aggregate. Therefore, researchers have proposed new methods to measure the electrical resistivity of coarse aggregate samples in the laboratory. There is a need to verify that the proposed methods yield results representative of the in situ conditions; however, no in situ measurement of the electrical resistivity of MSE wall backfill is established. Electrical resistivity tomography (ERT) provides a two-dimensional (2D) profile of the bulk resistivity of backfill material in situ. The objective of this study was to characterize bulk resistivity of in-place MSE wall backfill aggregate using ERT. Five MSE walls were tested via ERT to determine the bulk resistivity of the backfill. Three of the walls were reinforced with polymeric geogrid, one wall was reinforced with metallic strips, and one wall was a gravity retaining wall with no reinforcement. Variability of the measured resistivity distribution within the backfill may be a result of non-uniform particle sizes, thoroughness of compaction, and the presence of water. A quantitative post processing algorithm was developed to calculate mean bulk resistivity of in-situ backfill. Recommendations of the study were that the ERT data be used to verify proposed testing methods for coarse aggregate that are designed to yield data representative of in situ conditions. A preliminary analysis suggests that ERT may be utilized

  14. 柔性加筋土复合体力学性能试验%Experimental study of mechanical properties of flexible geosynthetic-reinforced soil complex

    胡幼常; 童金田; 刘胜军; 张文明


    In order to study the mechanical properties of flexible geosynthetic-reinforced soil complex,a series of unconfined compression tests were conducted in laboratory.The test samples were made up of sand reinforced respectively with nonwoven geotextile,geogrid,both geotextile and fiber,or both geogrid and fiber.Each sample varied in either the number of reinforcement inclusions or the density of sand.Based on the analysis of the test results,some conclusions are drawn as follows.1) There is an appropriate match among the geotextile strength,the reinforcement spacing and the sand density.The samples making according to such match have not only high compressive strengths but also large failure compressive strains.2) Sand reinforced with both geotextile and fiber has a higher compressive strength than that of one reinforced only by geotextile at the same conditions;but only a little difference between them while both the sand has a relatively low density and the reinforcement spacing is small.3) While the compressive strain is larger,the compressive strength of the geogrid-reinforced sand is much lower than that of geotextile-reinforced sand,which is perhaps due to the large difference between the geogrid and the sand in tensile stiffness resulting in sliding at the geogrid-soil interface.4) Compared with the geogrid-reinforced sand,the sample reinforced with both geogrid and fiber has a higher compressive strength at low compressive strain and a larger failure compressive strain due to the fiber inclusions.%为了研究柔性加筋土复合体的基本力学特性,分别对无纺土工布加筋砂、土工格栅加筋砂、"土工布+纤维"综合加筋砂和"土工格栅+纤维"综合加筋砂制作的多组试样完成了一系列组合工况下的无侧限抗压试验.得到以下主要结论:1)土工布的强度和加筋层间距应与砂的密度相匹配,此时,两者协同工作性最好,加筋砂土极限强度高,破坏应变大;2)相同情

  15. Development stages of Holocene soils formed in loess and loess bearing sediments at the Roman wall (Limes) in the Wetterau (Hesse, Germany)

    Kühn, P.; Felix-Henningsen, P.


    About 2000 years ago the Romans built a wall through Europe - named Limes (lat. border) in Middle Europe and Hadrian's wall in UK - with the aim to protect the borders of their empire. In many parts the Limes was constructed by digging a trench and by accumulating the excavated soil material at one side of the trench. The upper decimetres of the wall are mainly made of calcareous sediments, because the trench was dug to a depth of C horizons which are composed of loess with high carbonate content. One prerequisite for research on pedogenesis is to obtain most precise data about the age of the parent material of soil formation. Regarding this, the Limes gives an excellent opportunity to distinguish different stages of Late Holocene soil development. The study area is part of the soilscape of the Wetterau (100 - 250 m asl) situated between Taunus and Vogelsberg in Hesse, Germany. The precipitation is around 500 mm per year. Wetterau's gentle rolling hills were originally covered with loess and periglacial slope deposits. The soilscape is characterized by (Albic) Luvisols, Haplic Phaeozems, Luvic Phaeozems as well as Calcaric Regosols on upper slopes and Anthrosols in footslope positions. Particulary Haplic Phaeozems and Luvic Phaeozems have been of a wider interest of pedogenic research, since they have been formed in the Early and Mid-Holocene and, therefore, they are relic. It is supposed that the Wetterau was a Chernozem soilscape during the Early Holocene changing to a soilscape characterised by (Luvic) Phaeozems and Luvisols during the Atlantic period. Results of archaeological research on the Roman wall in the Wetterau showed that the wall was constructed in the 2nd century AD and that it had different functions over time. In this context soil investigations revealed three different stages of Holocene soil development: (i) a youngest (recent) soil situated in the wall, (ii) a paleosol conserved below the wall and (iii) a soil developed in the area nearby the

  16. Make the rhizosphere great again: microbes build walls in soil that roots pay for

    Hallett, Paul; Naveed, Muhammad; Raffan, Annette; Bengough, Glyn; Feeney, Debbie; Brown, Lawrie; Georgy, Timothy; Cooper, Laura; Daly, Keith; Koebernick, Nicolai; Sinclair, Ian; Roose, Tiina


    Plant roots physically manipulate surrounding soil to ease penetration, provide anchorage, improve water and nutrient capture and enhance gaseous exchange, with knock-on impacts to habitats for microorganisms, soil stabilisation and sequestering of carbon. Root traits that alter soil physical properties include exudates, root hairs, the extent of soil drying and root architecture. We are exploring the extent that different root traits physically manipulate soils, drawing on near isogenic crop lines that differ in root hairs, architecture and exudation, and new physical approaches that quantify rhizosphere impacts. These approaches include hydromechanical testing that bridge soil physics, soil biology and materials science, small-scale measurements and non-invasive imaging to measure the rhizosphere directly. We use these data in image based models that describe retention and transport of water and nutrients in the rhizosphere. Micromechanics tests have found that barley root exudates initially disperse soil, followed by gelling after secondary decomposition of these exudates by microbes. Maize root exudates, on the other hand, caused a large amount of gelling of the soil, whereas this impact decreased with microbial decomposition. From our data on exudate viscosity, contact angle and surface tension, we have modelled the direct impact on water retention and transport in the rhizosphere, using 3D CT imaging with Synchrotron XRay CT with sufficient resolution to detect root hairs. From these images, pore structure changes were found to be affected by the presence of root hairs in barley. This could have implications to resource capture by plants, showing a secondary impact of root hairs beyond expanding the volume of soil that roots access.


    付明堂; 梁醒培; 李恒


    采用有限元法对钢筋混凝土筒仓仓壁受力进行了静力有限元计算,得到了仓壁的详细应力分布情况,以及钢筋和混凝土共同受力时各自承担的环向拉力.基于计算结果对仓壁受力进行了分析,结果表明:我国的《混凝土筒仓设计规范》能够满足仓壁的静力强度要求.%The static stress of reinforced concrete silo wall was calculated using finite element method. The detailed stress distribution of the silo wall and the circumferential tensile forces respectively applied on the steel bar and concrete were obtained when the steel bar and concrete bore force together. Based on the calculation results, the article analyzed the force condition of the silo wall, and the results showed that the Code for design of reinforced concrete silos could meet the requirement for the static strength of the silo wall.

  18. 重复荷载作用下加筋格宾挡土墙动力特性%Dynamic Characteristics of Reinforced Gabion Walls Subjected to Cyclic Loading

    李昀; 杨果林; 林宇亮


    A large-scale model test of reinforced gabion walls was designed and performed. The model wall filled with red sandstone for construction was built with a length of 3.0 m, height of 2. 0 m, and width of 0. 85 m. PVC-coated heavy galvanized double twisted hexagonal wire mesh was used in the test, and the wire mesh specimens were 80 mm x 100 mm cell sizes. A series of tests were performed with different input sine wave frequencies and amplitudes. The dynamic characteristics and dynamic responses of model wall under cyclic loading were discussed. The results show that (1) the inside and outside of reinforced gabion wall under two million times repeated loads does not appear significant local and overall damage, the structure is stable and anti-destructive; (2) when the vibration frequency reaches 10 Hz, there are great changes of vertical and horizontal acceleration and displacement response of the reinforced gabion wall. The results are helpful to reveal the mechanism of reinforced gabion wall's instability under cyclic loading.%设计并完成了大型加筋格宾挡墙模型试验.试验模型尺寸为3.0 m x0.85 m×2.0 m(长×宽×高),填料采用工程现场用红砂岩材料制备.双绞合六边形金属格宾网由PVC包裹,并镀锌防腐,网面单元尺寸为80 mm x100 mm.通过输入不同幅值和频率的正弦波激励,探讨重复荷载作用下模型挡墙的动力特性与动力响应规律.试验结果表明,加筋格宾挡墙在重复荷载作用200万次下,挡墙内外部未出现明显的局部和整体破坏,其结构具有良好的稳定性和抗破坏性.当振动频率达到10 Hz时,加筋格宾挡墙的竖向、水平加速度和竖向、水平位移反应变化极大.试验结果有助于揭示挡墙在重复荷栽作用下的失稳机制.

  19. Reliability-based design optimization of reinforced concrete structures including soil-structure interaction using a discrete gravitational search algorithm and a proposed metamodel

    Khatibinia, M.; Salajegheh, E.; Salajegheh, J.; Fadaee, M. J.


    A new discrete gravitational search algorithm (DGSA) and a metamodelling framework are introduced for reliability-based design optimization (RBDO) of reinforced concrete structures. The RBDO of structures with soil-structure interaction (SSI) effects is investigated in accordance with performance-based design. The proposed DGSA is based on the standard gravitational search algorithm (GSA) to optimize the structural cost under deterministic and probabilistic constraints. The Monte-Carlo simulation (MCS) method is considered as the most reliable method for estimating the probabilities of reliability. In order to reduce the computational time of MCS, the proposed metamodelling framework is employed to predict the responses of the SSI system in the RBDO procedure. The metamodel consists of a weighted least squares support vector machine (WLS-SVM) and a wavelet kernel function, which is called WWLS-SVM. Numerical results demonstrate the efficiency and computational advantages of DGSA and the proposed metamodel for RBDO of reinforced concrete structures.

  20. 局部配筋对页岩空心砖墙体抗震性能影响试验研究%Experimental Study on Seismic Behavior of Shale Hollow Brick Masonry Walls Influenced by Partial Reinforcement

    陈万山; 杨德健


    作为非承重结构材料,页岩空心砖能够较好地替代黏土砖.但空心砖墙体抗震性能较差,严重影响其在工程中的应用.局部配筋是提高砌体结构抗震性能的主要方法之一.为研究局部配筋对页岩空心砖墙体抗震性能的影响,对3种砌筑形式6组墙体进行了低周反复荷载试验.研究了局部配筋对该结构承载力、滞回性能、延性和耗能能力等方面的影响.研究结果表明:局部配筋不仅可以提高墙体承载力,而且可以显著提高墙体抗震性能和变形性能.%Shale hollow bricks can take the place of common bricks to some extent. But the weak seismic behavior of hollow brick masonry walls affects the application of the hollow bricks in the engineering. Partical reinforcement in the wall can improve the seismic performance of walls. In order to investigate the effect of seismic behavior of this structure, the low cyclic reversed lateral loading tests on six pieces of shale hollow brick masonry walla which used three bricklaying patterns have been carried out. The bearing capacity, hyateretic characteristics, ductility and energy dissipation were researched. The result of investigation shows that setting steel reinforcement in the wall not only can improve the bearing capacity of the masonry walls,but also can greatly improve the seismic behavior and the deformation behavior of the wall.

  1. Construction of the curtain wall made of carbon fiber reinforced concrete. Sangenjaya Carrot Tower; Tanso sen`i hokyo konkurito wo mochiita katen uoru no seko - sangenjaya kyarotto tawa -

    Hara, H.; Sasaki, M.; Honda, Y. [Tokyu Construction Co. Ltd., Tokyo (Japan)


    The characteristics of the carbon fiber reinforced concrete (CFRC) for the construction of the above-titled curtain walled tower, its full-size property test and the result of building work are reported. In the beginning, the composition of CFRC materials and their blending are described and the relationship between the mixing time with a mixer destined for that purpose and the mortar flow and the quality control on the CFRC control specimens are explained, followed by a description on the CFRC weight, water content, the use of stainless reinforcement bars to suppress corrosion, dry shrinkage, the relationship between bending strength and Young coefficient, durability, the bonding state obtained by traction test and so forth, together with an outline of the test result, It is also clarified that an ultimate strength taken in member design is assumed to be the one at the moment of bending crack at a high-wind occurring once during 150 years, and the safety is assured by the reinforcement of deformed stainless bars. Further, the working steps from the form construction to the fluorocarbon resin painting are indicated enumerating requirements for the curtain wall properties in terms of water-tightness, windresisting, aseismicity and so on. Lastly, some improvements made through the experiments and the state of construction work are noted. 5 refs., 14 figs., 4 tabs.

  2. Investigation of deformation of elements of three-dimensional reinforced concrete structures located in the soil, interacting with each other through rubber gaskets

    Berezhnoi, D. V.; Balafendieva, I. S.; Sachenkov, A. A.; Sekaeva, L. R.


    In work the technique of calculation of elements of three-dimensional reinforced concrete substructures located in a soil, interacting with each other through rubber linings is realized. To describe the interaction of deformable structures with the ground, special “semi-infinite” finite elements are used. A technique has been implemented that allows one to describe the contact interaction of three-dimensional structures by means of a special contact finite element with specific properties. The obtained numerical results are compared with the experimental data, their good agreement is noted.

  3. Study of the ruining behaviour of a structure with reinforced concrete carrying walls; Etude du comportement a la ruine d'une structure a murs porteurs en beton arme

    Manas, B


    Nuclear facility buildings must be constructed with the respect of para-seismic rules. These rulesare defined according to the most probable seismic risk estimated for the sites. This study concerns the ruining behaviour of a structure made of reinforced concrete walls. In a first part, a preliminary study on reinforced concrete is performed with the Castem 2000 finite elements code. This study emphasizes the non-linear phenomena that take place inside the material, such as the cracking of concrete and the plasticization of steels. In a second part, predictive calculations were performed on a U-shape structure. This structure was submitted to earthquakes of various magnitudes and the response of the structure was analyzed and interpreted. (J.S.)

  4. Soil-Structure Interaction Analysis of Tall Reinforced Concrete Chimney with Piled Raft and Annular Raft under Along-Wind Load

    B. R. Jayalekshmi


    Full Text Available A three-dimensional (3D soil-structure interaction (SSI analysis of 300 m high reinforced concrete chimneys having piled annular raft and annular raft foundations subjected to along-wind load is carried out in the present study. To understand the significance of SSI, four types of soils were considered based on their flexibility. The effect of stiffness of the raft was evaluated using three different ratios of external diameter to thickness of the annular raft. The along-wind load was computed according to IS:4998 (Part 1-1992. The integrated chimney-foundation-soil system was analysed by commercial finite element (FE software ANSYS, based on direct method of SSI assuming linear elastic behaviour. FE analyses were carried out for two cases of SSI (I chimney with annular raft foundation and (II chimney with piled raft foundation. The responses in chimney such as tip deflection, bending moments, and base moment and responses in raft such as bending moments and settlements were evaluated for both cases and compared to that obtained from the conventional method of analysis. It is found that the responses in chimney and raft depend on the flexibility of the underlying soil and thickness of the raft.

  5. Evaluation of Reinforcement Effect of Ends Soil in Pipe Jacking Machine Launching and Arrival Based on Orthogonal Experiment Method%基于正交试验法的顶管端头土体加固效果评价

    吴飞; 孙阳; 邵国建; 钱军; 刘勇


    The end soil reinforcement of pipe jacking launching and arrival is the key to successful tunnel construction. In this paper,the formula of stability coefficient is given when the longitudinal thickness of reinforced soil is greater than the height of the tunnel entrance,which is an improvement for the existing sliding instability theory;and then three dimensional FEMis used to calculate the surface settlement when the H-steel support is removed and when the shield crossed the reinforced area.Finally,the orthogonal experiment method is adopted to analyze the influence of longitudinal thickness of reinforced soil,the strength of reinforced soil and the thickness of cover on reinforcement effect of end soil. The results show that:1)The thickness of cover and the strength of reinforced soil affect the maximum ground surface settlement slightly;but the thickness of reinforced soil affects the maximum ground surface settlement greatly.2)The maximum ground surface settlement can be reduced by increasing the longitudinal thickness of end soil.3 )The thickness of cover is negatively correlated to the stable coefficient of end soil;and the thickness of reinforced soil and strength of reinforced soil is positively correlated to the stable coefficient of end soil.The results can provide an effective way to decide the scheme of end soil reinforcement in the future.%顶管始发与到达时的端头土体加固是隧道施工成败的关键。对现有的滑移失稳理论做出改进,得出了端头土体纵向加固厚度大于洞口高度时的稳定系数计算公式;使用三维有限元数值模拟,计算拔除洞口 H 型钢支护和机头穿越加固区后的端头土体地表沉降;最后采用正交试验法分析了纵向加固厚度、加固强度和上覆土厚度3种因素对端头土体加固效果影响的主次关系。结果表明:覆土厚度和加固强度对端头土体地表最大沉降值影响并不显著,而加固厚度对其影响很大,


    杨佳林; 薛伟辰


    Precast concrete sandwich wall panel is a new type of insulation wall which performs well both in structural bearing and thermal insulation. It is consisted of internal and external concrete wall-board, insulating layers and connectors, etc. According to different material, connector can be divided into three categories: common reinforced connector, alloy metal connector and fiber reinforced plastic ( FRP) connector. FRP connector has the property of low thermal conductivity, good durability and high strength. Which can decrease the heat transfer coefficient of sandwich wall panel, and has bright foreground in engineering applications. This paper introduces classification,research and application, standards and specifications of FRP connector, and offers the prospect for research trend of FRP connector in future.%预制混凝土夹芯保温墙体是集承载与保温一体化的新型预制保温墙体,该墙体由内外层混凝土墙板、中间保温层及连接件等组成.按照材料的不同,连接件主要分为普通钢筋连接件、金属合金连接件和纤维塑料(FRP)连接件三种.FRP连接件具有导热系数低、耐久性好、强度高的特点,可有效降低墙体的传热系数,具有广阔的工程应用前景.本文介绍了预制混凝土夹芯保温墙体FRP连接件分类、国内外研究与应用进展和技术规范情况,并对今后FRP连接件研究工作进行了展望.

  7. LNG储罐外墙温度应力分析及预应力筋设计%Thermal stress analyses on external wall of LNG storage tank and the design of prestressed reinforcement

    程旭东; 朱兴吉


    The external wall of large-scale LNG storage tank is mainly built by the prestressed concrete and it has complicated stress distribution and deformation. Based on the introduction to a computing method for the thermal stress of prestressed concrete wall, we deduced computing formulae of the cylindrical wall thermal stress, the prestressed reinforcement of external wall subjected to the temperature difference load and other common loads, and locations of the maximum hoop stress by means of theoretic analyses. Consequently, a optimized scheme for prestessed reinforcement was then given. The results show that the ultra-low temperature liquid in the inner tank will produce a huge thermal stress to the prestressed concrete external wall and the maximum hoop thermal stress can reach up to a half of the tensile strength of concrete, which makes the external wall more dangerous when it is subject to internal pressure. Therefore, the temperature difference load should be considered in the design of the loop prestressed reinforcement. Numerical simulations taken afterwards by applying the automatic dynamic incremental nonlinear analysis (ADINA) finite element software to set up various discrete models of prestessed concrete verified not only the correctness of formulae deduced but also the prestessed reinforcement optimized scheme that makes the stress distribution and deformation of external wall more sound.%大型LNG储罐的外墙一般由预应力混凝土建造,其应力分布及变形比较复杂.在介绍预应力混凝土外墙温度应力计算方法的基础上,采用理论分析的方法,推导出了圆筒形外墙温度应力的计算公式,外墙在温差荷载及其他普通荷载作用下预应力筋的计算公式以及最大环向应力所在位置计算公式,进而给出了预应力筋结构调整的方案.研究结果表明,内罐的超低温液体会使预应力混凝土外墙产生很大的温度应力,环向温度应力最大可达混凝土抗拉强


    刘佩; 郭猛; 李挺; 姚谦峰


    Similar to the multi-grid composite wall reinforced by steel bars, an improved multi-grid composite wall reinforced by light steels is proposed, where the steel bars in grid beams and columns are replaced by light steels. To apply the improved composite in large-bay high-rise buildings, its seismic performance should be examined. 1/2 scale multi-grid composite walls reinforced by light steels, as well as by steel bars, were tested under reversed cyclic loading. Damage procedures, load-beating capacity and ductility were compared. It is found that both kinds of walls fail in shear, and the damage propagates from the filling blocks to grids made up of grid beams and columns, and finally to the edged frame. Compared with using steel bars, using light steels to reinforce composite walls, with a 17% increase of steel, generated a yielding capacity of 54.3% larger and an ultimate capacity of 53.1% larger. The stiffness behavior and energy dissipation capacity of the improved composite wall were better too, while the ductility capacity of the two composite walls was almost the same.%轻钢龙骨框格密肋复合墙是在普通RC密肋复合墙的基础上,以轻钢龙骨代替肋梁肋柱中钢筋龙骨而形成的一种改进型密肋复合墙,为使密肋结构在大开间、中高层建筑结构中的应用成为可能,对轻钢龙骨框格密肋复合墙体抗震性能开展试验与理论研究十分必要。设计进行了1/2比例轻钢龙骨密肋复合墙体与标准RC复合墙体的低周反复荷载试验,对比研究改进前后密肋复合墙在破坏形态、承载力、刚度、延性等主要抗震性能方面的差异。试验结果表明,轻钢龙骨复合墙与普通RC复合墙均呈整体剪切型破坏,遵循砌块-框格-外框的破坏顺序;在用钢量增加17%的条件下,前者屈服荷载较后者提高了54.3%,极限荷载提高了53.1%,刚度及耗能性能亦明显优于后者;延性方面两者表现基

  9. 某带隔板联体钢筋混凝土筒仓裂缝成因分析%The Reason Analysis on the Induced Crack of Conioined Reinforced Concrete Silos with Cross Wall

    曾银枝; 潘立


    某联体筒仓由三仓组成,中仓带隔板,在使用期间仓壁出现多条明显裂缝.本文通过对该联体排仓进行有限元模拟计算,对不同工况的贮料荷载引起仓壁和隔板的应力变化进行了分析,将计算裂缝宽度和配筋与实际情况进行了对比,给出了仓壁裂缝的形成原因和技术说明.%One conjoined reinforced concrete cement silo is made up of 3 single silos, and the cross wall is set in the middle one. In this paper, the model of conjoined silos was computed by finite element method, and the element stress under the different load conditions was researched. At the same time, the calculated crack width and amount of reinforcing bars were compared with practical situation. At last, the reason on the induced crack in the silo walls is analyzed and explained.


    周晓悦; 章雪峰


    A 20-story office building of frame-shear wall structure was being built in 7 degree area. When the 10th floor was being built, it is found that 4 wall-columns' grade of concrete strength was less than C40 in the 4th floor. The concrete-replacing method was used to solve this problem. The effect of reinforcement is good with the reasonable temporary supports and the grouting material which is early-strength, high-strength and flow automatically. All of the reinforcement process was in the monitoring.%某20层框架剪力墙结构办公楼位于7度抗震设防区,在施工至第10层时,发现第4层4片墙柱混凝土强度严重偏低,不能满足原设计C40的强度要求.经过比选,确定采用分批置换混凝土法进行加固,通过合理布置临时支撑,采用具有早强、高强、自流性的灌浆料浇筑,并对加固过程进行全程监测,取得良好的加固效果.

  11. 浅谈基础墙、柱竖向钢筋无接头施工控制%Introduction to No Joint Construction Control of Foundation Wall and Column Vertical Reinforcement



    文章通过建筑物基础墙、柱插筋连接的几种传统做法与无接头施工控制在抗震方面的比较,凸显基础墙、柱竖向钢筋无接头施工在节约钢筋材料、缩短工期等方面的效果,彰显其在建筑施工方面的优越性,这不仅是对开展科技创新活动的积极响应和应用,也是展示企业科技创新的窗口。%This paper, through the comparison of traditional method of building foundation walls and pillars reinforced connection and no joint construction control in the earthquake, highlights the effect of no joint construction of foundation walls and column vertical reinforcement in saving steel material and shortening the construction period, reveals its advantages in the construction aspect, it is not only a positive response and application for the science and technology innovation activity, but also is the window to show the enterprises' technological innovation.

  12. Application of Concrete Cutoff Wall in Reinforcement of Earth Rock Dam Seepage Control%混凝土防渗墙在土石坝防渗加固中的应用



    Earth rock dam seepage safety problems occupy an important position in the overall security, directly affecting the safe operation of the dam.Concrete diaphragm wall as the main body of water retaining structure of seepage prevention and reinforcement system,anti-seepage effect is most reliable.On the basis of materials and technology analysis,the paper summarizes the problems on design,reinforcement of concrete anti-seepage wall in earth rock dam seepage prevention and construction methods.%土石坝的渗流安全问题在整体安全中占有重要地位,直接影响大坝的运行安全。混凝土防渗墙作为挡水建筑物加固防渗体系的主体部分,防渗效果最为可靠。文章在分析材料及其工艺的基础上,对土石坝防渗加固中混凝土防渗墙的设计、施工方法等问题进行初步总结。

  13. 窗间墙锚固配筋砖混结构教学楼抗震性能试验研究%Experimental study on seismic performance of brick-concrete masonry school buildings with wall piers reinforced with anchored reinforcements

    吴昊; 赵世春; 许浒; 张蓬勃; 吴刚


    Quasi-static tests on two half-scale two-story brick-concrete sub-structure models were carried out in order to improve the seismic performance of brick-concrete masonry school buildings. The wall piers between openings were partially reinforced with horizontal reinforcements that were reliably anchored using vertical reinforcements. The failure modes, load bearing capacity, deformability, rigidity degradation, ductility and hysteretic behavior of the two models, as well as failure modes of piers and failure mechanism of longitudinal walls were investigated. The results indicate that a story mechanism occurs in ordinary masonry model with the piers failing in shear failure. And the longitudinal walls exhibit strong spandrel-weak pier failure mechanism. However, partially reinforced wall piers are characterized by flexural failure with horizontal cracking in the mortar bed joints. Spandrels are severely damaged due to the formation of global failure mechanism. Strong pier-weak spandrel failure mechanism is guaranteed with uniform drift distribution. The level of damage, energy dissipation capacity and ductility of model are significantly improved.%为改善砖混结构教学楼的抗震性能,通过对其纵向窗间墙局部配筋并在墙体两端采用竖向钢筋进行锚固配筋,按照1/2的缩尺比例设计了2个砖混子结构模型.采用拟静力试验分别对普通窗间墙和配筋窗间墙的子结构模型的破坏模式、承载能力、变形能力、刚度退化、延性、耗能性能以及窗间墙的破坏模式和纵墙的破坏机制等进行了分析.结果表明:普通窗间墙模型表现为层间破坏机制,窗间墙发生剪切破坏,纵墙发生“强梁弱柱”式破坏;窗间墙局部配筋并进行锚固的模型发生整体型破坏,窗间墙弯曲破坏,纵墙的破坏机制具有“强柱弱梁”特征,层间变形均匀,模型的破坏形态、耗能能力和延性等均得到改善.

  14. 基于变形加固理论的岩土边坡稳定和加固分析%Stability and reinforcement analysis of rock and soil slope based on deformation reinforcement theory

    刘耀儒; 黄跃群; 杨强; 宋胜武; 冯学敏


    The traditional rigid-body limit equilibrium method and finite-element-based strength reduction method has some problems in stability and reinforcement analysis. Based on deformation reinforcement theory (DRT), a stability analysis method of slope is presented with elastoplastic finite element analysis. Plasticity complementary energy(PCE) is used to evaluate the whole stability of slope; and safety factor of slope can be obtained through the PCE curve with strength reduction factor. Reinforcement location and force can be determined by unbalance force distribution in the slope. Possible sliding surface also can be located on the boundary that direction reverse of unbalance force occurs. Three classical examples of slopes has been modeled and analyzed. The safety factor and reinforcement key location and force have been determined by the PCE curve and unbalance force distribution. The results indicate that the DRT based on nonlinear finite element analysis is effective in analysis of stability and reinforcement for rock and soil slopes. The failure process can be reflected by the development of unbalanced force with the strength reduction.%传统的刚体极限平衡法和强度折减法在分析边坡稳定和加固时存在一定的局限性.基于变形加固理论,建立了基于弹塑性有限元分析的边坡稳定和加固分析方法.以余能范数作为边坡整体稳定评价的指标,通过强度参数降低过程中的余能范数的变化来确定边坡的整体稳定安全系数.加固的关键部位和加固力的大小通过边坡中不平衡力的分布来确定.滑动面则 由方向相反的、成对的不平衡力的分界面来确定.针对3个经典边坡算例,分析了强度参数逐渐降低过程中的余能范数的变化和不平衡力的分布,确定了边坡的稳定安全系数以及相应的加固关键部位和加固力的大小.结果表明,变形加固理论基于岩土的三维非线性有限元分析,以此来进行边坡的

  15. Denaturing gradient gel electrophoresis fingerprinting of soil bacteria in the vicinity of the Chinese Great Wall Station, King George Island, Antarctica.

    Pan, Qi; Wang, Feng; Zhang, Yang; Cai, Minghong; He, Jianfeng; Yang, Haizhen


    Bacterial diversity was investigated in soil samples collected from 13 sites around the Great Wall Station, Fildes Peninsula, King George Island, Antarctica, using denaturing gradient gel electrophoresis (DGGE) of 16S rRNA genes. The classes alpha-, beta-, and gamma-Proteobacteria, as well as the phylum Actinobacteria, were found to be the dominant bacteria in the soils around the Great Wall Station. Although the selected samples were not contaminated by oil, a relationship between soil parameters, microbial biodiversity, and human impact was still seen. Sample sites in human impacted areas showed lower bacterial biodiversity (average H' = 2.65) when compared to non-impacted sites (average H' = 3.05). There was no statistically significant correlation between soil bacterial diversity and total organic carbon (TOC), total nitrogen, or total phosphorus contents of the soil. Canonical correlation analysis showed that TOC content was the most important factor determining bacterial community profiles among the measured soil parameters. In conclusion, microbial biodiversity and community characteristics within relatively small scales (1.5 km) were determined as a function of local environment parameters and anthropogenic impact.

  16. Denaturing gradient gel electrophoresis fingerprinting of soil bacteria in the vicinity of the Chinese Great Wall Station, King George Island, Antarctica

    Qi Pan; Feng Wang; Yang Zhang; Minghong Cai; Jianfeng He; Haizhen Yang


    Bacterial diversity was investigated in soil samples collected from 13 sites around the Great Wall Station,Fildes Peninsula,King George Island,Antarctica,using denaturing gradient gel electrophoresis (DGGE) of 16S rRNA genes.The classes α-,β-,and γ-Proteobacteria,as well as the phylum Actinobacteria,were found to be the dominant bacteria in the soils around the Great Wall Station.Although the selected samples were not contaminated by oil,a relationship between soil parameters,microbial biodiversity,and human impact was still seen.Sample sites in human impacted areas showed lower bacterial biodiversity (average H' =2.65) when compared to non-impacted sites (average H' =3.05).There was no statistically significant correlation between soil bacterial diversity and total organic carbon (TOC),total nitrogen,or total phosphorus contents of the soil.Canonical correlation analysis showed that TOC content was the most important factor determining bacterial community profiles among the measured soil parameters.In conclusion,microbial biodiversity and community characteristics within relatively small scales (1.5 km) were determined as a function of local environment parameters and anthropogenic impact.

  17. Contribution to the understanding of the behaviour of reinforced concrete shear walls under seismic loading: contribution of experiment and modeling to the design; Contribution a la comprehension du fonctionnement des voiles en beton arme sous sollicitation sismique: apport de l'experimentation et de la modelisation a la conception

    Ile, N


    This thesis deals with aspects of seismic behaviour of reinforced concrete shear walls (RCSW). Its objective is to introduce a useful modelling approach for addressing the non-linear response of a large variety of RCSW and to identify several aspects in which this numerical approach could be implemented into design applications. Firstly, the characteristics of the behaviour of RCSW under seismic loading, some design principles and different modelling approaches are discussed. As an important lack of knowledge in several fields was identified, it was considered that three types of shear walls deserve more attention: slightly reinforced slender walls; U-shaped walls and heavily reinforced squat shear walls. A local modelling approach is adopted and the material constitutive models are described in details. Secondly, the behaviour of the two mock-up, CAMUS I and II, tested on the shaking-table during the CAMUS programme, which are slightly reinforced and designed according to the French code PS92 is simulated using a 2-D finite element model (FEM). For comparison purposes, the case of the CAMUS III mock-up, designed according to EC8, is considered. We are then dealing with the case of U-shaped walls under dynamic and cyclic loading. The results obtained from numerical simulations, based on a 3-D shell FEM, are compared with those obtained from tests carried out in the frame of the ICONS programme. Finally, the numerical model is applied to the case of heavily reinforced squat shear walls (similar to those used in the nuclear power plant buildings) subjected to shear loading. A 2-D FEM is considered in order to simulate the behaviour of three different walls, which were tested pseudo-dynamically during the SAFE programme. The results from both experimental and numerical studies are compared and discussed. The most important factors affecting the behaviour of RCSW are highlighted. Different examples of possible contributions to design are presented. (author)

  18. Foundation Reinforcement of A Sluice in Soft Soil Area%软土地区某水闸基础加固研究

    方大勇; 杜秀忠; 杨光华; 李川; 孙昌利; 王飞


    某水闸存在深厚软土层, 地基处理采用水泥搅拌桩复合地基, 检测时发现部分区域搅拌桩存在质量问题, 下部不成桩. 通过计算分析和综合考虑, 设计采用静压预应力管桩进行基础加固. 施工前进行了试桩和静载试验, 并根据试验结果采用泡沫垫层等对加固方案进行了调整. 通过监测资料可知, 加固区的沉降与计算沉降基本一致, 和非加固区的沉降协调较好, 很好地达到了预期的加固效果, 对用管桩加固软基水闸基础有很好的参考价值.%A sluice is located in the thick soft soil layer, and the foundation of the sluice is treated with mixing piles.It is found that the pile can not form in the detection of stake-base.The method of strengthening foundation using pressed-in piped piles has been taken into account when designing and analyzing.The method has been added foam cushion after getting the experimental parameters by testing pile and static test.The measuring settlement of reinforce area is close to the calculation by comparing monitoring data.The deformation compatibility condition between reinforce area and non-reinforce area are well.The expected good result is reached, and it has a good reference value on similar projects.


    张艳军; 于沉香; 凌飞; 严稳平; 刘续; 陈铂


    This paper aims to improve the brittle fracture characteristics of cement soil and to study the engineering properties and mechanical mechanism of asbestos fiber reinforced soft soil.It adds the asbestos fiber into fly ash and cement soil.Thus it creates a new kind of composite soil and carries out a series of experiments on the new soil.In these experiments,asbestos fiber is added into fly ash and cement soil with different ratios(0%~9%),which results in different composite soil samples with different content of asbestos fiber.All of the composite soil samples are subjected to the direct shear test,the unconfined compression test,the diametral compression test and the scanning electron microscopy test (SEM).Thus the mechanical behavior and mechanism of fiber reinforced soft soil are illustrated.It is found that the combination of asbestos fiber and fly-ash cement can significantly enhance the strength and stability of soft soil and improve brittle fracture characteristics of cement soil.There is a range of optimal content of asbestos fiber regarding the enhancement of the strength value of the composite soil.This range is between 3%~6%.Other asbestos fiber content outside the range can reduce the enhancement effect.%为研究石棉纤维加固软土的效果和机理,改善水泥土的脆性破坏特点,提出将石棉纤维的物理加筋作用与水泥、粉煤灰的化学加固作用相结合,通过对不同纤维掺量(0%~9%)的石棉纤维粉煤水泥复合土进行直剪试验、无侧限抗压强度试验、劈裂试验、扫描电镜试验,进而对石棉纤维加筋水泥土的强度性质和影响机理进行探讨。研究表明,石棉纤维配合水泥与粉煤灰能显著提高软土的强度和稳定性,改善水泥土的破坏形式。水泥粉煤灰配比一定时,石棉纤维增强水泥复合土各强度指标值存在最优掺量,纤维添加量在3%~6%之间,石棉纤维的加筋效果在水泥土中能得到

  20. 分层填土作用在挡土墙上的主动土压力%Active Soil Pressure on Retaining Wall With Layered Backfills



    基于土的塑性极限分析理论,考虑墙后分层填土的滑动变形协调条件,探讨了分层填土作用在挡土墙上主动土压力的计算方法,得出了一些有益的结论.%Based on soil plasticity and limit analysis theory,together with sliding harmonious condition of layered backfills,calculating method of active soil pressure on retaining wall with layered backfills is proposed,and corresponding conclusions are also made in this paper.

  1. Test speed and other factors affecting the measurements of tree root properties used in soil reinforcement models

    Cofie, P.; Koolen, A.J.


    Measured values of the mechanical properties of tree roots are found to be affected by a number of factors. Shear properties of tree roots are found to be partly influenced by size of the testing equipment, level of soil compaction, deformation of the root material and estimated width of the shear z

  2. U 型现浇配筋混凝土薄壁空心装饰柱施工技术%On construction technique of U-shaped cast-in-place reinforced concrete thin-wall hollow decoration columns



    The paper describes the craft features for the U-shaped cast-in-place reinforced concrete thin-wall hollow decoration columns,illus-trates the construction craft procedure and material requirements by combining with its construction craft principle,and researches the construc-tion quality,safety and environment protection control measures,so as to achieve better economic and social benefits.%描述了 U 型现浇配筋混凝土薄壁空心装饰柱施工的工艺特点,结合其施工工艺原理,阐述了施工工艺流程及材料要求,并对施工质量、安全、环保控制措施进行了研究,以取得良好的经济、社会效益。

  3. 振孔切喷截渗墙技术在堤防消险加固中的应用%Application of vibrating hole cutting spraying intercepting seepage wall technique in dike damage prevention and dike reinforcement

    王永明; 郝群; 张秀宏


    The paper introduced the application of the vibrating hole cutting spraying intercepting seepage wall technique in the urban dike damage prevention,dike reinforcement and intercepting seepage.The technical theory,engineering design,construction technique,quality check for the vibrating hole cutting spraying are discussed in this paper.%介绍振孔切喷截渗墙技术在城区堤防消险加固截渗工程中的应用。其中包括振孔切喷技术工艺原理、工程设计、施工工艺、质量检查方法等。

  4. Fabrication and Characterization of Multi-Walled Carbon Nanotube (MWCNT) and Ni-Coated Multi-Walled Carbon Nanotube (Ni-MWCNT) Repair Patches for Carbon Fiber Reinforced Composite Systems

    Johnson, Brienne; Caraccio, Anne; Tate, LaNetra; Jackson, Dionne


    Multi-walled carbon nanotube (MWCNT)/epoxy and nickel-coated multi-walled carbon nanotube (Ni-MWCNT)/epoxy systems were fabricated into carbon fiber composite repair patches via vacuum resin infusion. Two 4 ply patches were manufactured with fiber orientations of [90/ 90/ 4590] and [0/90/ +45/ -45]. Prior to resin infusion, the MWCNT/Epoxy system and NiMWCNT/ epoxy systems were optimized for dispersion quality. Scanning electron microscopy (SEM) and optical microscopy (OM) were used to determine the presence ofcarbon nanotubes and assess dispersion quality. Decomposition temperatures were determined via thermogravametric analysis (TGA). SEM and TGA were also used to evaluate the composite repair patches.

  5. Analysis of a Floodplain I-Wall Embedded in Horizontally Stratified Soil Layers During Flood Events Using Corps I-Wall Software Version 1.0


    net active and net passive pressures are constructed and presented in Figure 4.31a. For the prescribed LHS flood loading, the I-Wall will rotate in a...The net passive pressures are plotted on the RHS of the sheet-pile wall. The final results are illustrated in Figure 4.32 by the presentation of the...or overburden induced horizontal pressures , if present ) is added on this diagram. b. The net passive pressure distribution is also formed on the

  6. Theory and practice of earth reinforcement

    Yamanouchi, T.; Miura, N.; Ochiai, H. (eds.) (Kyushu Sangyo Univ. (Japan))


    95 papers are presented in 5 sections: (1) tests and materials: strength and durability tests, corrosion problems of materials, contrivance and characterization of new material, and the new application of conventional materials involving natural fibres; (2) shallow and deep foundations: the basic theory, development of the design methods and their applications in soft grounds and in road construction; (3) slopes and excavations: the theory of slope reinforcement, reinforcing techniques of natural and cutoff slopes, application for slope protection, the ground reinforcement accompanied by excavation, and the temporary reinforcement method in excavation works in soft grounds; (4) embankments: the guideline for design, the reinforcement method of embankment foundations, the reinforcement at the boundary between soft ground and embankment, the damage of reinforcement during construction; and (5) wall structures: the reinforcement theory of retaining walls, design methods for retaining wall reinforcement, the reinforcement of backfill materials, jointing techniques of reinforcement materials, and the monitoring system. Includes a paper on the friction characteristics of polypropylene straps in reinforced minestone.

  7. 泡沫填充帽形加筋结构复合材料壁板成型工艺研究%Composite Reinforced Foam-filled Cap-shaped Wall Structure of Manufacturing Process

    李向苏; 尹龙; 李敏


    This paper dealt with the manufacturing processing of the foam-filled cap-shaped reinforced composite wall. The results said that, the composite's properties can meat the need of second bonding of the cap-shaped reinforced composite wall. The surface treatment style of using the 400# sand paper between the skin and the cap- shaped structure was feasible, the processing of pressure at the room temperature can ensure the composite components' inner quality and the thickness tolerance, and the cap-shaped composite structures' inner quality and surface quality can meet the design demands if wrapped the cap-shaped structures with the sulfured air pad rubber at the second bonding.%针对某型机泡沫填充帽形加筋结构复合材料机翼壁板开展了成型工艺研究。结果表明,壁板所用复合材料的性能满足帽形加筋壁板二次胶接的工艺需求;在帽形加筋长桁与蒙皮进行二次胶接前对胶接部位采用400#砂纸进行打磨,可以保证胶接性能;采用室温加压工艺可以保证复合材料构件的内部质量和厚度精度要求;在帽形加筋壁板进行二次胶接固化时采用已硫化的Airpad橡胶对帽形长桁进行包覆,可以保证帽形加筋长桁的表面质量和内部质量。

  8. 日光温室土墙传热特性及轻简化路径的理论分析%Heat transfer process of soil wall in Chinese solar greenhouse and its theoretical simplification methods

    李明; 周长吉; 周涛; 尹义蕾; 富建鲁; 王志强; 齐长红


    为减小日光温室土墙厚度,该研究在分析土墙温度变化的基础上提出了土墙轻简化路径并进行了理论分析。根据测试分析,土墙可划分为用于储蓄热量的蓄热层和防止热量从蓄热层向室外方向流失的保温层。土墙86.9%的部分为保温层。模拟结果表明使用由47 cm厚夯土和7 cm厚聚苯板(热阻等于3.13 m厚夯土保温层)构成的复合墙在夜间的放热量与3.6 m厚土墙相近。使用保温材料替代夯土保温层来减薄土墙在理论上可行。另外,根据模拟,当土壤20 cm深处温度提高至23℃后,土壤供热量可超过测试条件下土壤和土墙放热量总和。为此,土墙在理论上可通过以下2条途径实现轻简化:1)使用保温材料建造墙体保温层;2)使用土壤蓄热替代墙体蓄热。%Soil wall of the Chinese solar greenhouse (hereafter referred to as “solar greenhouse”) has problems of occupying large area and damaging the cultivation land. The simplification of soil wall, which means decreasing the thickness and soil use of the soil wall, becomes very important. The purpose of this study is to develop simplification methods of soil wall. A simplification wall with less soil use was proposed based on the measured temperature of soil wall and analysis of feasibility of those methods. The tested solar greenhouse was located in Yongqing county, Lanfang city, Hebei province (116°44′ E, 36°27′ N). It is 50 m long and 10 m wide. The top and bottom thicknesses of the soil wall were 2.0 and 5.3 m, respectively. Its average thickness was 3.6 m. The test period was from Dec. 01, 2013 to Mar. 30, 2014. During that time, the tested solar greenhouse was used to growing cucumber with surface irrigation. The heat insulation sheet of the solar greenhouse was rolled up and down at 8:30 am and 5:00 pm daily, respectively. The wind vent was open if the indoor air temperature was high during daytime. The indoor and

  9. Experimental study of reinforced expansive soil slope in freeze-thaw environment%冻融环境下加筋膨胀土边坡力学模型试验与研究

    徐丽丽; 张滨; 李兆宇; 吴志琴


    针对寒区膨胀土边坡冻胀问题,提出采用土工织物加筋处理技术。通过加筋处理及未处理两组室内冻土力学模型试验对比分析,研究在冻融循环作用下土工织物加筋膨胀土边坡的运行机制和效果。试验结果表明:①在土体冻结过程中,未处理的膨胀土边坡不均匀冻胀明显,土工织物加筋能有效抑制结构不均匀冻胀;②土工织物对水分的迁移有阻隔作用,加筋土处理模型的冻深略大于未处理模型;③碎石聚氨酯固脚具有一定的保温防冻胀作用。%For freeze injury of expansive soil slope , a technology using geotextile reinforced was handled .In accordance with the comparation and analysis of the treated and untreated frozen mechanical model test , the operation mechanism and effects of geotextile-reinforced expansive soil slope under freezing thaw cycle conditions are analyzed.Conclusion: ① In the process of soil freezing , untreated expansive soil slope uneven heaving obvious, geotextile-reinforced structure can effectively suppress uneven frost heave; ②Geotextile can block water migration in the soil , frozen deep of geotextile-reinforced model is slightly larger than the untreated models; ③Elastocoast can increase heat resistance;the Elastocoast protection-foundation has heat preservation effect .

  10. 钢筋混凝土剪力墙非线性单元模型的研究%Study on analytical model of reinforced concrete shear walls

    汪梦甫; 宋兴禹; 阴斌松; 区达光


    In this paper, analogous frame model (AFM) and multiple vertical line element model (MVLEM) have been improved. The improved AFM, MVLEM and multi-layer shell element model (MLSEM) have been applied to the inelastic static and dynamic response analysis of structural walls. Three isolated cantilever walls with different axial compressive ratios and a 14-story RC tube-in-tube structure are selected as illustrative examples. A comparison between analytical and experimental results indicates that the improved AFM is suitable for the inelastic response calculation of structural walls with medium axial compressive ratio, the MLSEM is proved to be most suitable for the prediction of inelastic behavior of structural walls with higher axial compressive ratios, and the improved MVLEM is suitable for the inelastic behavior and response calculation of structural walls.%本文首先对等效框架模型、多竖直杆单元模型作了改进.然后应用改进等效框架模型、改进多竖直杆单元模型及分层壳单元模型,对不同轴压比的三片剪力墙构件模型与一个14层筒中筒结构模型进行了计算分析,并与实验结果作了比较.结果表明:改进多竖直杆单元模型在所有情况下均可取得较好结果,是适用性较强的剪力墙非线性单元模型;多层壳单元模型在轴压比较大时可取得很好的结果,当轴压比较小时,应用多层壳单元模型应慎重;改进等效框架模型只在轴压比适中时可取得较好结果,其他情况下可能会引起较大的计算误差.


    于庆峰; 赵含章


    在前人研究的基础上,对加筋土挡土墙试验原型进行了改进.以不同超载下墙面板的土压力、墙面板的位移、拉筋的拉力等变化过程为依据,对加筋土挡土墙的工作机理进行了探索.测试结果分析表明:加筋土挡土墙通过发生一定的侧向位移使拉筋发挥作用;墙面板所受的土压力随着竖向土压力的变化而变化,呈现先增大再减小的过程;拉筋对土体的侧限作用发挥到一定程度后,墙面板的土压力将要开始随着拉筋内力的增大而减小;拉筋的内力越大,拉筋对土体的侧限作用发挥越充分,墙面板的位移增加越缓慢.%On the basis of previous studies, Earth Retaining Wall Testing Prototype was improved. According to the transformation process of different earth pressure of an overloaded Shingle nail, displacement of a Shingle nail and the tension of Lacing Wire, the Matrix Raid of Reinforced Earth Retaining Wall is explored. The analysis of the testing results shows: Reinforced Earth Retaining Wall enables lacing wire to work by a certain lateral displacement. Earth pressure of Shingle nails changes with the shift of Vertical earth pressure , showing a process of increasing firstly and decreased then. When the Lateral Restraint Function of Lacing Wire goes to a certain extent, the earth pressure of the Shingle nail will decrease with the increase of internal force of Lacing Wire . The stronger the internal force of Lacing Wire is, the fuller the Lateral Restraint Function of Lacing Wire is, and the slower the replacement of the Shingle nail is.

  12. Research on Stability of High Liquid Limit Soil Embankment Reinforced with Geogrid%土工格栅加筋高液限土路堤的稳定性研究

    陈兴专; 洪宝宁; 刘鑫


    The constitutive model of soil is established by Plaxis,and the control variable method is used to analyze the stability factors,such as the role of tendon-soil interface,reinforced pitch,reinforced position and so on .Some useful conclusions are drawed:the better the soil’s quality and reinforcement stiffness,the better are the reinforcement effect and embankment stability;the stability of bottom reinforcement is obviously better than that of the middle and upper;the reinforcement encryption can not effectively improve the stability of embankment .Through the field tests of a highway in Guangdong,it is proved that the optimized design could reduce the surface subsidence and deep horizontal displacement effectively,and also improve the stability of embankment .%运用Plaxis软件,建立土体本构模型,采用控制变量法分析筋土界面作用、加筋间距、加筋位置等对高液限土路堤稳定性的影响.得出结论:土质越好,筋材刚度越大,加筋效果越明显,加筋路堤也越稳定;底部加筋的稳定性明显高于中部和上部加筋;格栅加密不能有效提高加筋路堤的稳定性.通过广东某高速公路现场加筋试验研究,验证了优化的加筋设计能较好降低高液限土路堤的表面沉降和深层水平位移,提高路基的稳定性.

  13. Soils

    Emily Moghaddas; Ken Hubbert


    When managing for resilient forests, each soil’s inherent capacity to resist and recover from changes in soil function should be evaluated relative to the anticipated extent and duration of soil disturbance. Application of several key principles will help ensure healthy, resilient soils: (1) minimize physical disturbance using guidelines tailored to specific soil types...

  14. 日光温室土墙体温度变化及蓄热放热特点%Temperature variation, heat storage and heat release characteristics of soil wall in solar greenhouse

    史宇亮; 王秀峰; 魏珉; 李清明; 刘福胜; 侯加林


    The solar greenhouse of soil wall, which has the advantages of good heat storage and low construction cost, is widely used in China. At present, the study on the heat storage and heat release performance of soil wall is an important hot spot, which can provide the theoretical basis for the simplification and thickness optimization of soil wall. In the paper, the sunken soil wall greenhouse serves as the research object in Taian, Shandong Province, China. The length is 50 m and the width is 10 m. The top and bottom thicknesses of the soil wall are 1.47 and 3.0 m, respectively. In order to get a better analysis of the heat storage and heat release performance of soil wall, the five testing layers of temperature were arranged in the north wall of greenhouse. The testing period was from Dec. 1st, 2014 to Jan. 30th, 2015. The outdoor weather conditions, indoor air temperature and interior wall temperature were monitored during the testing period. The variation regularity of the indoor and interior wall temperature was analyzed according to the monitoring data in the coldest season (from Dec. 20th, 2014 to Jan. 19th, 2015). The results showed that the testing point temperature of wall surface and interior wall (0.1-0.6 m) presented periodicity variation regularity with the indoor temperature variation in greenhouse, and temperature fluctuation amplitude reduced gradually, at the same time the phase was lags obviously along the wall thickness direction. Moreover, it showed that the interior wall (0-0.6 m) could be considered as the heat storage and heat release body in the soil wall. The heat storage body in the soil wall had large temperature fluctuation, which could be used for storing heat during daytime and releasing heat into the solar greenhouse during night. Besides that, the temperature fluctuation of testing point behind 0.7 m tended to the stabilization, which was in the process of the steady-state heat transfer from the soil wall to outdoors and could be

  15. The Processing Technology of the Core Dam Material of the High Gravel Soil Core Wall Dam%高砾石土心墙坝心墙料加工技术



    砾石土心墙堆石坝已逐渐成为世界高坝建设的主流坝型之一,砾石土心墙料加工是大坝施工的关键环节之一。从砾石土的筛分、级配骨料的加工、心墙料的掺合三个环节介绍了高砾石土心墙坝心墙料加工技术.对于高砾石土心墙坝施工具有指导意义。%The gravel soil core wall rock fill dam has become one of the mainstream dam types in high dam construction around the world and the gravel soil core wall material processing is one of the keys in dam construction. This paper introduces the processing technology of the core wall material high gravel soil core wall dam from the three process of the screening of gravel soil, the processing of graded aggregate and the blending of core wall material, which has a good practical and guiding significance to the construction of high gravel soil core wall dam.

  16. Water Resistance, Hydration Product and Microstructure of Glass Fiber Reinforced Magnesium Oxychloride Cement Exterior Wall Cladding%玻镁外墙挂板的抗水性、水化产物和微观结构

    董金美; 余红发; 刘倩倩; 李颖; 林启红


    Bending mechanical properties and deformations in natural state and wet state under water of common and high-performance glass fiber reinforced magnesium oxychloride cement ( GRMC ) exterior wall cladding were tested in this study. Hydration product components and microstructure were observed by X-ray diffraction ( XRD ) and scanning electron microscopy ( SEM). The results indicated that, in wet state under water, the main hydration product 5 ·1 ·8 was hydrolysed, microstructure is destroyed and bending strength is decreased for common GRMC exterior wall cladding. For high-performance GRMC exterior wall cladding with a complex water-repellent admixture and mixed minerals, the main hydration product 3 ·1 ·8 is stable existing in cement matrix and microstructure has been changed little. The sample reveals high water resistance. So, hydration product components and microstructure stability of GRMC exterior wall cladding are important prerequisites for high water resistance.%试验测定了普通玻镁外墙挂板、掺加复合抗水外加剂和矿物掺合料的高性能玻镁外墙挂板在自然和浸水状态下的弯曲力学性能和变形性能,并运用X射线衍射仪(XRD)和扫描电镜(SEM)分析了水化产物的组成和微观结构特征.结果表明:在浸水条件下,普通玻镁外墙挂板的主要水化产物5 ·1·8相发生了分解,破坏了微观结构,导致其抗弯强度降低;而掺加复合抗水外加剂和矿物掺合料的高性能玻镁外墙挂板的水化产物5·1·8相保持稳定,微观结构未发生变化,显示出较高的抗水性.因此,玻镁外墙挂板的水化产物组成和微观结构的稳定性是确保其抗水性的重要前提.

  17. 带斜筋单排配筋中高剪力墙抗震性能试验研究%Research of Seismic Behavior of Mid-rise RC Shear Wall With Single Row of Steel Bars and Inclined Reinforcement

    张建伟; 蔡翀; 曹万林; 李琬荻; 吴蒙捷


    In order to study the effect of inclined reinforcement arrangement on seismic behavior of mid-rise RC shear wall with single row of steel bars, the low cyclic loading tests for four mid-rise RC shear walls with single row of steel bars and inclined reinforcement and one without inclined reinforcement were carried out respectively. The failure mode, hysteretic behavior, load-carrying capacity, ductility, rigidity degeneration and energy dissipation capacity of five test specimens were contrastively analyzed. The influences of intersection angle between inclined reinforcement and horizontal direction as well as the proportion of web reinforcement and inclined reinforcement on the seismic performance of mid-rise RC shear walls were also revealed. The test results indicate that different reinforcement arrangements have little influence on failure mode, ultimate load-carrying capacity and ductility for the mid-rise RC shear wall with single row of steel bars, but the inclined reinforcement can reduce shear slipping of the wall to a certain extent, and the inclined reinforcement positioned as fan-shape is more effective. The mid-rise RC shear walls with single row of steel bars and inclined reinforcement show slower stiffness attenuation and better energy dissipation capacity than that of the shear wall without inclined reinforcement.%为了解斜筋布置形式对单排配筋混凝土中高剪力墙抗震性能的影响,进行了4个带斜筋和1个不带斜筋的单排配筋混凝土中高剪力墙低周反复荷载试验,对比分析了各剪力墙的破坏形态、滞回性能、承载力、延性、刚度退化和耗能能力,研究了斜筋角度和配筋比例对中高剪力墙抗震性能的影响。结果表明:对于低配筋量的单排配筋混凝土中高剪力墙,墙体分布钢筋的配置形式变化对其破坏形态、极限承载力和延性影响不大;配置斜筋可在一定程度上减小墙体剪切滑移变形,斜筋呈扇形布置

  18. Behavior of fiber reinforced mortar joints in masonry walls subjected to in-plane shear and out-of-plane bending

    Armwood, Catherine K.

    In this project, 26 fiber-reinforced mortar (FRM) mixtures are evaluated for their workability and strength characteristics. The specimens tested include two control mixtures and 24 FRMs. The mixtures were made of two types of binders; Type N Portland cement lime (Type N-PCL) and Natural Hydrated Lime 5 (NHL5); and 6 fiber types (5 synthetic fibers and one organic). When tested in flexure, the results indicate that majority of the synthetic fiber mixtures enhanced the performance of the mortar and the nano-nylon and horse hair fibers were the least effective in improving the mortar's modulus of rupture, ductility, and energy absorption. Four FRMs that improved the mortar's mechanical properties most during the flexural strength test were then used to conduct additional experiments. The FRM's compressive strength, as well as flexural and shear bond strength with clay and concrete masonry units were determined. Those four mixtures included Type N-PCL as the binder and 4 synthetic fibers. They were evaluated at a standard laboratory flow rate of 110% +/- 5% and a practical field flow rate of 130% +/- 5%. Results indicate that the use of fibers decreases the compressive strength of the mortar most of the time. However, the bond strength test results were promising: 81% of the FRM mixtures increased the flexural bond strength of the prism. The mixtures at 110 +/- 5% flow rate bonded better with concrete bricks and those ate 130+/-5% flow rate bonded better with clay bricks. The results of the shear bond strength show 50% of the FRM mixtures improved the shear bond strength. The FRM mixtures at 110+/-5% flow rate bonded with clay units provided the most improvement in shear bond strength compared to control specimen results. Along with detailed discussions and derived conclusions of these experiments, this dissertation includes recommendations for the most feasible FRM for different applications.

  19. Up Against The Wall: The Effects of Climate Warming on Soil Microbial Diversity and The Potential for Feedbacks to The Carbon Cycle

    Kristen M. DeAngelis


    Full Text Available Earth’s climate is warming, and there is evidence that increased temperature alters soil C cycling, which may result in a self-reinforcing (positive, microbial mediated feedback to the climate system. Though soil microbes are major drivers of soil C cycling, we lack an understanding of how temperature affects SOM decomposition. Numerous studies have explored, to differing degrees, the extent to which climate change may affect biodiversity. While there is ample evidence that community diversity begets ecosystem stability and resilience, we know of keystone species that perform functions whose effects far outweigh their relative abundance. In this paper, we first review the meaning of microbial diversity and how it relates to ecosystem function, then conduct a literature review of field-based climate warming studies that have made some measure of microbial diversity. Finally, we explore how measures of diversity may yield a larger, more complete picture of climate warming effects on microbial communities, and how this may translate to altered carbon cycling and greenhouse gas emissions. While warming effects seem to be ecosystem-specific, the lack of observable consistency between measures is due in some part to the diversity in measures of microbial diversity.

  20. 河闸除险加固工程右岸翼墙振冲碎石桩试桩探讨%Discussion on Vibroflotation Stone Column Test Pile of Will Wall on Right Bank of River Sluice Reinforcement Engineering



    Shuangtaizi river sluice is an important component of the flood control system on Liao River downstream,playing vital roles for the development and construction of Panjin City, and obtaining obvious social and economic benefits.The main construction parts of vibroflotation tone column are the foundation of shallow hole gate chamber,foundation of will walls on left and right banks,foundation of water pumping station and foundation of management and running center.This paper describes the purpose of vibroflotation stone column test pile of the will wall on the right bank of Shuangtaizi river sluice reinforcement engineering,conformation of test pile parameters,test pile scope and quantity of test pile method and test pile construction.%双台子河闸是辽河下游防洪体系的重要组成部分,为盘锦市的开发建设发挥了极其重要的作用,并取得了明显的社会效益和经济效益。振冲碎石桩主要施工部位为浅孔闸闸室基础、左右岸翼墙基础、提水泵站基础及调度管理中心基础。文章对双台子河闸除险加固工程右岸翼墙振冲碎石试桩的目的、试桩的参数确定及试桩的方法中的试桩范围和数量、试桩施工进行了阐述。

  1. Experimental study on soil moisture content of geogrid-reinforced clay under freezing-thawing cycle%冻融循环下格栅加筋粘土土体含水率试验研究

    赵荣飞; 宓永宁; 姜广田; 金丹; 高微


    通过一系列室内含水率测试试验,研究了格栅加筋粘土在多次冻融循环条件下土体含水率的变动情况,探讨了填料压实度,加筋层数和初始含水率对冻融后土体含水率变动的影响规律.结果表明,压实度对土体ωi影响最大,低压实度时,△ω1为正值,高压实度时,△ω1为负值;加筋层数次之,ω1值随加筋层数增加而减小,在压实度高的土体中尤为显著;初始含水率影响最弱,仅在土体压实度较低时,较大的初始含水率会引起较大的△ω1值.%Through a series of lab-tests on moisture content of soil, the change of the moisture content of the grid-reinforced clay under freezing-thawing cycle is studied herein, and then the law of the impact from the compaction degree, the reinforcement layers and the initial moisture content of the soil on the moisture content of the soil under freezing-thawing cycles are discussed. The result shows that the compaction degree has the greatest impact on the soil body ωi, i. e. △ω1 is positive when the compaction degree is low and △ω1, is negative when the compaction degree is high; meanwhile, the number of the reinforcement layers only has a secondary impact on the soli body, i. e. the value of ω1, is decreased along with the increase of the number of the reinforcement layers, while it is significant in the highly compacted soil; moreover, the impact from the initial moisture content is much less and the greater value of △ω1 is to be only arisen from a greater initial moisture content when the compaction degree of soil is low.

  2. Experimental Study on Seismic Behavior of Composite Core Walls With Steel Tube-reinforced Concrete Columns%钢管混凝土叠合柱边框组合核心筒抗震性能试验研究

    董宏英; 耿海霞; 张建伟; 曹万林; 杨信强


    为了比较带钢管混凝土叠合柱边框组合核心筒与带钢管混凝土边框组合核心筒的抗震性能,进行了1个钢管混凝土叠合柱边框组合核心筒模型和1个钢管混凝土柱边框组合核心筒模型的低周反复荷载试验研究,2个模型均按1/6缩尺.在试验基础上,分析比较了2个核心筒的承载力、延性、滞回特性、刚度及其衰减过程、耗能能力和破坏特征.研究表明,钢管混凝土叠合柱边框组合核心筒比钢管混凝土柱边框组合核心筒的抗震性能显著提高;承载力简化计算模型的计算结果与实测结果符合较好.%The cyclic tests are performed in order to compare the seismic behavior of two 1/6 scale composite core walls with different columns, one with concrete filled steel tube columns and the other with steel tubereinforced concrete columns. Based on the experiment, load-carrying capacity, ductility, hysteretic property, stiffness and degradation, energy dissipation and damage characteristics of the two specimens are compared. It is shown that the seismic behavior of the core walls with steel tube-reinforced concrete columns is better than those with concrete filled steel tube columns. The mechanical model for calculating load-carrying capacity of the new RC composite core walls is proposed. And the calculating results agreed well with the results from the experiments.

  3. A study of the key problems of reinforcement of flood control wall in Shanghai%上海地区防汛墙加固工程关键问题



    In the past years, there were some key technical problems in reinforcement of flood wall, such as ambiguous causes in analysis of dangerous situations, no unified standards for flood defense, contradictions of planning standards and current situations, mismatches of protective standards and urban development, unreasonable reinforcement scale, etc. In this paper, the examples of risk situations are collected to analyze the main factors that lead to the mentioned problems. Firstly , we present a study of the relationships among these various factors and then contrast planning standards with present status. In addition, further researches have been done which deconstruct the contradictions in current protected standards and analyze the reasons of unreasonable proposed scale for the reinforcement of floodwall. Main reasons of the dangerous situations include boundary conditions change, illegal operation of vessels, structural safety deficiencies, land subsidence, and engineering impact caused by projects that are adjacent to or pass through rivers. Various dangerous situations are caused by one or more factors; thus in order to raise the security levels in upstream regions, the standards of protection should be checked from overall defense standards which have been corrected by measured hydrological data. Furthermore, for ascertaining the principles of project scale of reinforcement, working conditions, hydrological features, the dangerous situation and the planning or standards evolution should be taken into account. At last, restrictive conditions should be settled on the shoreline of dock and ship lock.%针对上海地区防汛墙在历年除险加固工程建设中出险原因分析不明、设防水平不一致、规划标准与现状存在矛盾、设防标准与现实发展不相匹配、加固规模拟定不合理等关键问题,通过收集出险事例,剖析了造成防汛墙出险的主要因素和各因素之间的关系,对比了规划标准、设

  4. Evaluation model of reinforcement structures of Small mass movement

    Gustavo Antonio Piazza


    Full Text Available Mass movements can be the result of elevated precipitation events and inadequate policies of land use. This study aims at diagnosing the performance of a hillside stabilization structure that suffered a landslide in the meteorological event at the Itajaí Valley in 2008, and to propose a simple method for evaluating reinforcement structures of small mass movement. The study area is located at BR–470 – km 45, near to the city limit of Gaspar and Blumenau, in Santa Catarina, South Brazil. Tests were performed to determine the infiltration rate and soil moisture, as well as a survey of the floristic composition and slope. The mass movement still takes place and the stabilization structure is compromised. The use of gabion wall and other geotechnical techniques for environmental recovery were insufficient to provide the hillside stabilization. To a greater efficiency we suggest: slope reduction; soil compaction; suitable planting species (ecologic succession; and implementation of a comprehensive drainage system.

  5. Evaluation of Interface Shear Strength Properties of Geogrid Reinforced Foamed Recycled Glass Using a Large-Scale Direct Shear Testing Apparatus

    Arul Arulrajah


    Full Text Available The interface shear strength properties of geogrid reinforced recycled foamed glass (FG were determined using a large-scale direct shear test (DST apparatus. Triaxial geogrid was used as a geogrid reinforcement. The geogrid increases the confinement of FG particles during shear; consequently the geogrid reinforced FG exhibits smaller vertical displacement and dilatancy ratio than FG at the same normal stress. The failure envelope of geogrid reinforced FG, at peak and critical states, coincides and yields a unique linear line possibly attributed to the crushing of FG particles and the rearrangement of crushed FG after peak shear state. The interface shear strength coefficient α is approximately constant at 0.9. This value can be used as the interface parameter for designing a reinforced embankment and mechanically stabilized earth (MSE wall when FG is used as a lightweight backfill and triaxial geogrid is used as an extensible earth reinforcement. This research will enable FG, recently assessed as suitable for lightweight backfills, to be used together with geogrids in a sustainable manner as a lightweight MSE wall. The geogrid carries tensile forces, while FG reduces bearing stresses imposed on the in situ soil. The use of geogrid reinforced FG is thus significant from engineering, economical, and environmental perspectives.

  6. 桩承式加筋路堤三维土拱效应试验研究%Experimental study of 3D soil arching in piled reinforced embankments

    曹卫平; 胡伟伟


    桩承式加筋路堤受力性状比较复杂,土拱效应对路堤的承载变形性状具有重要影响。通过三维土拱效应模型试验,研究桩-土相对位移、路堤高度、桩帽净间距和水平加筋体拉伸强度等因素对桩土应力比及路堤沉降的影响。结果表明:土拱效应发挥程度与桩-土相对位移密切相关,存在一个临界桩-土相对位移使得桩土应力比达到最大值,该临界桩-土相对位移约为6~8 mm。路堤高度与桩帽净间距之比越大,桩土应力比越大,路堤顶面差异沉降越小;桩帽宽度与桩帽净间距之比越大,桩土应力比越大,路堤顶面差异沉降越小。设置水平加筋体能有效提高桩土应力比并减小路堤顶面沉降;路堤越低,水平加筋体对桩土应力比的提高作用及对路面沉降的减小作用越明显;水平加筋体拉伸强度越高,这种作用越明显。桩承式加筋路堤三维土拱效应等沉面高度与桩帽净间距之比约为3.5。%Soil arching has a notable influence on the behavior of piled reinforced embankment for its mechanically complex nature. A series of 3D model tests are conducted to explore the influence of the pile-soil relative displacement, embankment height, pile-cap spacing and horizontal reinforcement tension strength on the stress concentration ratio as well as the embankment settlement. The test results show that: soil arching is closely related to the pile-soil relative displacement and there exists a critical pile-soil relative displacement of approximate 6 to 8 mm which makes the stress concentration ratio reaching its maximum value. The bigger the ratio of embankment height is to the pile-cap clear spacing, the bigger the stress concentration ratio and the smaller the differential settlement on the surface of the embankment are;a bigger ratio of the cap width to the pile-cap clear spacing will result in a bigger stress concentration ratio and a smaller

  7. Determination and analysis on solar radiation of trapezoidal soil wall and soil surface in solar greenhouse%日光温室土质梯形墙体与地表太阳辐射测定分析

    张亚红; 白青; 封美琦; 孙利鑫


      为研究日光温室梯形土质后墙与地表太阳辐射分布规律,采用辐射探头分别与墙体和地表平行的方式测定了后墙内表面上、中、下3点和地表面南北方向2点的太阳辐射照度。在墙体表面测试并比较了同一测点2种测法(探头水平安装与倾斜安装)的区别。结果表明,在墙体同一测点2种测法所测太阳辐射照度有显著性差异,倾斜法所测值大于水平法所测值,倾斜法所测值应为墙体表面实际得到的太阳辐射照度。在不开风口的情况下,墙体:温室后墙上、中、下3点表面日均太阳辐射照度依次升高。晴天,上、中、下3点日辐射总量分别占墙体日辐射总量的21.6%、36.6%和41.8%;阴天,这一比例为22.5%、34.0%和43.5%;地面:南北方向2测点太阳辐总量总是南部大于北部,南北2点太阳辐射总量分别占地面辐射总量的62.0%和38.0%;阴天的比值为63.2%和36.8%;墙体与地面:地面太阳辐射总量高于墙体。晴天,墙体表面太阳辐射总量为8.117 MJ/m2,地面为8.280 MJ/m2,地面值略高于墙体,差异不显著;阴天,墙体与地面太阳辐射总量分别为0.984和2.068 MJ/m2,地面太阳辐射总量显著高于墙体太阳辐射总量。该研究为探讨该类型温室热环境提供参考。%In a solar greenhouse, solar radiation is the only resource of energy, thus functioning as the essential prerequisite for balancing its energy. The wall and the ground are the major recipients of solar radiation as well as the major elements for preserving the energy. In Northern China, 95% of the greenhouses have soil walls;therefore, it is meaningful to study solar radiation in the greenhouses with soil walls. Radiation probes were used to study the law of solar radiation distribution on a trapezoidal soil back wall and ground. The actual solar radiation on the greenhouse wall and ground was measured by balancing the probes



    The co-authors consider the problem of analysis of building structures in respect of combined effects of forces and temperatures. Results of fire tests of reinforced concrete walls and slabs are presented. Overview of the analysis of the fire resistance of reinforced-concrete buildings is also provided. As a result of the research, numerical solutions were obtained in respect of deflections, stresses, deformations and internal forces arising in a reinforced concrete bearing wall and plate...

  9. Optimization of Drilling Parameters for Reducing the Burr Height in Machining the Silicon Carbide Particle (SiCp) Coated with Multi Wall Carbon Nano Tubes (MWCNT) Reinforced in Aluminum Alloy (A 356) Using Meta Modeling Approach

    Sangeetha, M.; Prakash, S.


    This paper explains the optimization of drilling parameters using meta modeling approach to reduce the burr height while machining Silicon Carbide Particle (SiCp) coated with Multi Wall Carbon Nano Tubes (MWCNT) and reinforced in aluminum alloy (A 356). The specimen is prepared by the combination of sonication and stir casting processes. The volume fraction of MWCNT used is 1.5% and the volume fraction of SiCp is 10%. The combination of input parameters for drilling the holes is designed using Taguchi experimental design technique. The input parameters chosen for drilling operations are spindle speed, feed rate and drill diameter. The ranges of input parameters are listed in Table 1. The tools used for drilling operation are made up of solid carbide drill bit. Meta model is a mathematical and statistical model whose second-order model can be fitted by factorial design. The optimization model can be improved significantly by the second-order model compared to the first-order model. Twenty-seven holes are drilled using vertical machining center in the prepared specimen (A 356/MWCNT coated SiCp). Desirability function shows the optimized values of input parameters to obtain minimum burr height. Meta modeling approach is used to design a model using input parameters and output response burr height. The residuals plot shows the predicted values are closer to the measured values. This plot explains that the Meta model is adequately used to predict the burr height. The optimized values of input parameters for obtaining minimum burr height are the combination of high speed, low feed and low drill diameter. The minimum value of burr height observed in this experiment is 0.002mm and it is obtained in the optimized combination of N3, f1 and d1.

  10. 察尔汗地区复合地基加固盐渍土效果试验%Experiment study on reinforcement effect of composite foundation in saline soils of Qarhan region

    张彧; 刘建坤; 房建宏; 徐安花


    采用动力触探试验和平板荷载试验,就砾石桩、强夯、强夯置换和冲击碾压4种方法对盐湖区察格高速公路盐渍土地基的加固效果,从桩体密实度、复合地基承载力、变形模量、桩土应力比等方面进行了分析.结果表明:①强夯置换墩的密实度低于砾石桩;②强夯置换加固效果最好,冲击碾压法效果最差,承载力两者相差166.9%;③夯击能是后3种加固工艺中决定加固效果的重要指标,其大小直接关系着加固后的承载力和变形模量的数值;④砾石桩桩土应力比约为3.36,强夯置换复合地基墩土应力比为2.05,砾石桩和强夯置换均可有效降低盐渍土天然地基的沉降.%Using SPT and slab loading test, the paper analyzed different reinforcement effects from four different reinforcement technologies-gravel piles method, dynamic compaction method, dynamic consolidation , dynamic replacement method and impact compacted method for Cha-Ge highway saline soils ground located in salt lake area, and got the following conclusions: ①The density of dynamic consolidation and dynamic replacement is lower than gravel piles of saline soils. ②Dynamic consolidation and dynamic replacement method has the best reinforcement effect, and impact compacted method has the worst. The gap is 166.9%. ③Tamping energy is important on reinforcement effect to the last three methods and it is related directly to the values of the strengthened bearing capacity and deformation modulus. ④The stress ratio of the pile and the soil between the piles is about 3.36, while the one of composite foundation for dynamic consolidation and dynamic replacement is about 2.05. Both technologies mentioned above are useful on reducing the settlement of natural saline soils foundation.

  11. Probabilistic analysis of soil: Diaphragm wall friction used for value engineering of deep excavation, north/south metro Amsterdam

    Buykx, S.M.; Delfgaauw, S.; Bosch, J.W.


    The excavation of deep building pits often requires a check against failure by uplift of low permeability ground layers below excavation level. Whenever the weight of these soil layers is less than the pore-water pressure underneath, measures to resist buoyancy are to be considered. The measures mos

  12. Effects of polyethyleneimine-mediated functionalization of multi-walled carbon nanotubes on earthworm bioaccumulation and sorption by soils.

    Petersen, Elijah J; Pinto, Roger A; Zhang, Liwen; Huang, Qingguo; Landrum, Peter F; Weber, Walter J


    Carbon nanotubes (CNTs) are often modified for different intended potential applications to enhance their aqueous stability or change properties such as surface charge. Such changes may also profoundly impact their environmental behaviors. Herein, we report the effects of modifying (14)C-labeled multiwalled carbon nanotubes (MWCNTs) with polyetheyleneimine (PEI) surface coatings to render them more stable in solution and to give them positive, negative, or neutral surface charges. These carbon nanotubes were used to test their sorption by soils and uptake and elimination behaviors by earthworms. Sorption results indicate nearly linear sorption isotherms for regular MWCNTs and nonlinear isotherms for modified MWCNTs, indicating that the PEI coatings influenced MWCNT interactions with soils. Nevertheless, there were minimal differences in the sorption results among the different soils for each type of nanotube despite differences in the soil organic carbon and cation exchange capacities. Differences in uptake behaviors by earthworms were not apparent among different types of PEI-MWCNTs and MWCNTs with limited absorption into organism tissues consistently observed. Elimination patterns were well fit with an exponential decay model suggesting that the worms can readily eliminate any accumulated MWCNTs.

  13. 土钉墙在工程应用中的问题及改进方法的探讨%Limitations of Soil Nail Wall in Engineering Application and the Improvement Method

    易丽丽; 聂俊; 潘泓


    Soil nail wall is widely used in supporting foundation pit excavation and brings great social and economic benefits. However, soil nail wall is blindly used in China at present. People are not aware of its limitations and applicable scope, giving rise to problems in the designing and construction which lead to lots of accidents. In view of this, we should have a comprehensive understanding of the action mechanism of soil nail wall. At the same time, we need to understand its superiorities and limitations and pay attention to its construction. This paper lays emphasize on problems in the use of soil nail wall, and gives advices to make it better. What' s more, we discuss the future use of soil nail wall, for example, the durability of soil nail wall, anti-seismic resistance, creep deformation, nondestructive examination, deformation estimation, composite soil nail wall and so on. Research on these aspects will be of far-reaching and promising importance.%土钉墙凭借一些显著的优越性被广泛应用于基坑工程的开挖支护,并带来了巨大的社会和经济效益.然而,国内存在大量盲目使用土钉墙的现象,由于没有认清适用范围,加上设计和施工中存在大量的问题,导致基坑安全事故屡见不鲜.因此需要全面认识土钉墙的作用机理,了解土钉墙的优缺点、重视其施工水平.针对土钉墙在岩土工程应用中存在的问题做了详细讨论,并提出了改进方法和土钉墙今后研究的方向,对土钉墙的耐久性、抗震、蠕变以及无损检测、变形的预测、复合土钉墙等方面展开研究将具有非常深远的意义和良好的发展前景.

  14. Discussion on the Treatment Method of Soft Soil Foundation Reinforcement in Strengthening Municipal Road Construction%加强市政道路建设中软土地基加固处理方法的探讨


      随着我国建设速度加快,道路建设遍布各地,然而在道路建设的过程中,遇到的困难也是越来越多,软土地基便是常常困扰着市政道路建设的主要问题之一。本文主要从软土地基的加固方法进行分析,充分介绍换填置换法、排水固结法、塑料排水板法、机械碾压和夯实法处理法、化学加固法、反压护道法等加固处理技术。%Along with our country to speed up the construct-ion speed, road construction is everywhere, but in the process of road construction, the difficulties also encountered more and more, soft soil foundation is one of the main problems that of-ten afflict municipal road construction. This article mainly ca-rries on the analysis from the method of soft soil foundation re-inforcement, the ful introduction of replacement replacement method, drainage consolidation method, plastic drainage board method, mechanical compaction and compaction method, che-mical grouting reinforcement technology, counter pressure ber-m method and so on.

  15. Comparative studies of multi-walled carbon nanotubes (MWNTs) and octadecyl (C18) as sorbents in passive sampling devices for biomimetic uptake of polycyclic aromatic hydrocarbons (PAHs) from soils.

    Li, Shibin; Anderson, Todd A; Maul, Jonathan D; Shrestha, Babina; Green, Micah J; Cañas-Carrell, Jaclyn E


    To avoid overestimating the risk of polycyclic aromatic hydrocarbons (PAHs), research is needed to evaluate the bioavailable portion of PAHs in the environment. However, limited PSDs were developed for a terrestrial soil system. In this study, two sorbents, octadecyl (C18) and multi-walled carbon nanotubes (MWNTs), were individually evaluated as sorbents in passive sampling devices (PSDs) as biomimetic samplers to assess the uptake of PAHs from soil. C18-PSDs were an excellent biomimetic tool for PAHs with a low molecular weight in complex exposure conditions with different soil types, types of PAHs, aging periods, and initial PAH concentrations in soil. The utility of MWNT-PSDs was limited by extraction efficiencies of PAHs from MWNTs. However, when compared to C18-PSDs, they had higher adsorption capacities and were less expensive. This study provides data regarding useful techniques that can be used in risk assessment to assess the bioavailability of PAHs in soil.

  16. Determination of n-alkanes contamination in soil samples by micro gas chromatography functionalized by multi-walled carbon nanotubes.

    Li, Yubo; Zhang, Runzhou; Wang, Tao; Wang, Yonghuan; Xu, Tianbai; Li, Lingfeng; Zhao, Weijun; Dong, Shurong; Wang, Xiaozhi; Luo, Jikui


    A new method for separation of 11 n-alkanes: octane, o-nonane, n-decane, n-undecane, n-dodecane, n-tridecane, n-tetradecane, n-pentdecne, n-hexadecath, heptadecane, n-octadecane in soil samples was developed. Kuderna-Danish (K.D.) concentrator enrichment prior to ultrasonic extraction and the silicone chromatography column purification and with gas chromatography flame ionization detection (GC-FID) could be used for n-alkanes determination. The micro channels of open tubular column were fabricated onto a silicon wafer to replace the quartz capillary chromatographic column. The column structure and analysis parameters that affected the column separation were investigated and optimized. Under optimal conditions, the extract reagent was centrifuged and collected. A silicone chromatography column and a K.D. concentrator were used for further clean-up and enrichment. Using this method, the limits of detection (LOD) and limits of quantification (LOQ) were obtained in the range of 0.03-0.15 and 0.1-0.5 mg kg(-1) in soil samples, respectively. The relative standard deviation (RSD) was under 12%. The optimized procedure that presented good analytical performance (with recoveries ranging from 56.5% to 89.2%), was successfully applied to determine n-alkane content in farmland soil samples adjacent to a highway. The results showed that the MWCNTs-functionalized column is capable of separating the alkane contaminations with high resolution in about 3 min, which is much shorter than that of GC-MS and other conventional analytical methods, demonstrating its great potential for rapid analysis.

  17. Experimental study on seismic behavior of multi-ribbed composite wall with steel reinforcement concrete frame column%型钢混凝土边框柱复合墙体抗震性能试验研究

    何明胜; 黄炜; 石磊


    Multi-ribbed composite wall with steel reinforcement concrete frame column (SCMRCW) is characterized by high bearing capacity and good seismic behavior, and it is the same with moderate-high storied structure. To show the seismic behavior of SCMRCW,we designed a 1/2 scaleed SCMRCW with 1:1 height-width ratio and two 1/3 scaleed SCMRCW with 2:1 and 3:1 height-width ratio, and carried out low frequency cyclic and reversed lateral load tests. We studied mechanical character, failure mode, bearing capacity, ductility, energy dissipation ability and deformation behavior etc. . The result indicates that the failure process of SCMRCW is similar to MRCW, but the bearing capacity , ductility and energy dissipation ability of SCMRCW is better than that of MRCW. The seismic behavior of the structure is enhanced apparently, when the steel reinforcement concrete frame column is set in MRCW, and the bearing capacity of SCMRCW is reduced with the increasing of height-width ratio, but ductility and energy dissipation ability are increased, and the advantage of shaped steel is obvious.%型钢混凝土边框柱复合墙体具有承载力高、抗震性能好的特点,适用于中高层结构.为研究这种结构形式的抗震性能,本文设计了高宽比为1∶1、模型比例为1/2及高宽比分别为2∶1与3∶1、模型比例为1/3型钢混凝土边框柱密肋复合墙体试件,并进行拟静力试验.根据试验结果,分析了型钢混凝土边框柱密肋复合墙体的受力特点、破坏形态、承载能力、延性、耗能以及变形等抗震性能.分析结果表明:型钢混凝土边框柱的破坏过程与普通密肋复合墙体相似;相同条件下,其承载力、延性及耗能能力都明显好于普通复合墙体;边框柱中加入型钢后,该结构体系的抗震性能得到明显提高;随着高宽比的增加,该结构的承载力减小,但延性、耗能增加,型钢的有利作用更加明显.

  18. Portable reinforcing timbering

    Trukhin, P.M.; Kan, Ye.V.; Novikov, V.Ya.; Popov, K.P.; Rusyaykin, I.P.; Sardov, A.I.


    The purpose of the invention is to improve reliability and safety of the timbering. This goal is achieved because in the portable reinforcing timbering which contains a cross beam connected on the edges to the support elements interacting with the permanent timbering frames, hydrostands with supports, assemblies for connecting the hydrostands to the cross beam, the support elements are turned towards each other and are attached at the bottom by stands that rotate on the cross beam, while the connecting assemblies are made in the form of easily detachable clamps. The connecting assemblies of the hydrostands with cross beams are made in the form of a cantilever and walls interacting with the base of the cross beam through the vertical ribs with slits in the shape of the base of the cross beam and with the hydrostand by horizontal ribs, and among themselves by vertical ribs of the cantilever and vertical slits in the wall. In addition, the rapidly detachable connection of the cantilever to the wall is made in the form of a lever with short supports interacting with the vertical slits and the round openings in their upper section on the cantilever ribs, and the diameter of the lever axis and the round openings of the slits is greater than the diameter of the lever supports and the vertical slits of the cantilever, while the inner distance between the supports equals the outer distance between the vertical ribs of the cantilever.

  19. Numerical analysis of instability soil-nailing wall in deep foundation pits containing soft soil layer at middle and deep parts%中深部含软弱夹层的深基坑土钉支护失稳破坏数值模拟分析

    单仁亮; 董洪国; 陈代昆


    以中核北京科技园综合楼深基坑项目在分层开挖与分层土钉支护中出现的边坡顶端土体开裂、坡底土体坍塌形式的失稳破坏现象为研究背景,运用FLAC3D有限差分软件进行模拟分析。数值模拟分析中考虑土层分布、基坑边坡坡度、土钉的排列方式、钢筋网喷射混凝土面层、含水层的孔隙水压力、分层开挖支护等因素,使模拟分析与实际相接近。根据基坑大小建立相应的基坑边坡三维模型,采用莫尔-库仑弹塑性模型计算基坑边坡在不同开挖支护阶段的位移变形,并通过后处理程序显示基坑整体、最大位移截面的位移云图,记录所设置的关键点处水平位移与沉降量。在工程实际分布开挖过程中,测量每次开挖支护所引起的边坡水平位移与沉降量。将数值模拟中所得节点水平位移、沉降量与两者的实测数值对比分析,由此判断基坑潜在滑裂面与可能出现坍塌的大致位置,为工程设计方案中关于变形量较大区域支护方式的整改提供重要参考。%The FLAC3D software is adopted to simulate and analyze the project based on some unstable and damage phenomena such as fracture of top soils of side slope and collapse of bottom soils of side slope during stagged excavating and construction of soil-nailing wall in a deep foundation pit of the building of Beijing Science Park of China National Nuclear Corporation. In order to ensure the reality of the numerical simulation approach, several factors are considered, in duding distribution of soil layers, gradient of side slope, arrangement pattern of soil nails, reinforced steel shotcrete surface, pore water pressure of aquifer, stagged excavation and support. According to the size of the deep foundation pit, the corresponding three-dimensional model is established. The Mohr-Coulomb elastic-plastic model is used to compute the displacement deformation of side slope at



    A composite panel having front and back faces, the panel comprising facing reinforcement, backing reinforcement and matrix material binding to the facing and backing reinforcements, the facing and backing reinforcements each independently comprising one or more reinforcing sheets, the facing...... by matrix material, the facing and backing reinforcements being interconnected to resist out-of-plane relative movement. The reinforced composite panel is useful as a barrier element for shielding structures, equipment and personnel from blast and/or ballistic impact damage....



    A composite panel having front and back faces, the panel comprising facing reinforcement, backing reinforcement and matrix material binding to the facing and backing reinforcements, the facing and backing reinforcements each independently comprising one or more reinforcing sheets, the facing rein...... by matrix material, the facing and backing reinforcements being interconnected to resist out-of-plane relative movement. The reinforced composite panel is useful as a barrier element for shielding structures, equipment and personnel from blast and/or ballistic impact damage....

  2. Shaking Table Model Test of Reinforced Concrete Shear Wall Structure%钢筋混凝土剪力墙结构模型振动台试验研究

    李峥; 高贺香


    针对7层剪力墙结构缩尺模型振动台试验,比较研究基底固定和考虑土一结构动力相互作用两种条件下的钢筋混凝土剪力墙结构的抗震性能.分析结构在地震波作用下的加速度响应、放大系数、变形性能、应变分布情况以及结构模型的动力特性.在模型试验的基础上,进一步利用有限元分析软件ANSYS进行了剪力墙结构的动力反应分析,得到结构的自振特性以及在地震作用下动力响应的数值解,验证了ANSYS有限元数值分析方法的合理性.%Through shaking table model test, the paper studied seismic behaviors of the shear wall structure comparing with fixing base and considertiom of soil-structure interaction.acceleration response, amplification factor, deformation property, strain distribution and dynamic properties of model under the action of the seismic waves are analyzed.On the basis of the modal analysis theory, Then a further dynamic analysis of the structure is progressed using finite element program ANSYS.The calculation results include numerical solution of free vibration characteristics and seismic responses of the structure under earthquake action.It is verified that the ANSYS finite element analysis method is reasonable.

  3. Emprego do saco herniário no reforço parietal nas hérnias inguinais indiretas do adulto Repair of inguinal indirect hernia using the hernial sac in reinforcement wall of adult

    Pedro Lúcio de Souza


    proposta de utilização do saco herniário, como um reforço da hérnia inguinal, mostrou-se um recurso de fácil e rápida execução, com custo operacional baixo, não expondo o paciente ao aumento do número de complicações.This prospective study reports 80 repairs of inguinal indirect hernias of groin. All patients were men, 18-65 years old, with internal inguinal ring ranging from 1cm to 3.5cm in diameter, corresponding to type 2 in Nyhus'classification of inguinal- femoral hernias. The objective was to investigate the probable advantages of using the hernial sac as an additional reinforcement, together with the usual, of posterior wall of the inguinal canal. The internal ring was encircled by a sling from the hernial sac graft. The patients were divided into two groups. In both groups, the statistical texts showed no siginificant diferences between averages of age, weight and height of the patients and between diameter of infernal ring. In the group A, the reinforcement was made by means of the iliopubic tract repair. In the group B, the hernial sac was applied as a reinforcing patch. the graft would then fit snugly against the cord to form a new internal ring. This technique is easy and spends, in average, nine minutes. Hernial sac is a tissue constituted predominantly of conjunctive fibers, fatty cels, blood vessels and straight muscular fibers until 25% of the cases. In the only patient who underwent reoperation, the graft was found to be transformed into a thick fibrous tissue barrier at the floor of the inguinal canal. After a 24-month follow-up, the author concluded that hernioplasty using the hernial sac in repair of inguinal indirect hernia offers a simplified, rapid and inexpensive solution. In addition, the operative means do not cause increase of post-operative complications.

  4. Basal Reinforced Piled Embankments

    Van Eekelen, S.J.M.


    A basal reinforced piled embankment consists of a reinforced embankment on a pile foundation. The reinforcement consists of one or more horizontal layers of geosynthetic reinforcement (GR) installed at the base of the embankment. The design of the GR is the subject of this thesis. A basal reinforce

  5. Basal Reinforced Piled Embankments

    Van Eekelen, S.J.M.


    A basal reinforced piled embankment consists of a reinforced embankment on a pile foundation. The reinforcement consists of one or more horizontal layers of geosynthetic reinforcement (GR) installed at the base of the embankment. The design of the GR is the subject of this thesis. A basal reinforce


    Braverman, J.I.; Miller, C.A.; Ellingwood, B.R.; Naus, D.J.; Hofmayer, C.H.; Bezler, P.; Chang, T.Y.


    This paper describes the results of a study to evaluate, in probabilistic terms, the effects of age-related degradation on the structural performance of reinforced concrete members at nuclear power plants. The paper focuses on degradation of reinforced concrete flexural members and shear walls due to the loss of steel reinforcing area and loss of concrete area (cracking/spalling). Loss of steel area is typically caused by corrosion while cracking and spalling can be caused by corrosion of reinforcing steel, freeze-thaw, or aggressive chemical attack. Structural performance in the presence of uncertainties is depicted by a fragility (or conditional probability of failure). The effects of degradation on the fragility of reinforced concrete members are calculated to assess the potential significance of various levels of degradation. The fragility modeling procedures applied to degraded concrete members can be used to assess the effects of degradation on plant risk and can lead to the development of probability-based degradation acceptance limits.

  7. Determination of uptake, accumulation, and stress effects in corn (Zea mays L.) grown in single-wall carbon nanotube contaminated soil.

    Cano, Amanda M; Kohl, Kristina; Deleon, Sabrina; Payton, Paxton; Irin, Fahmida; Saed, Mohammad; Shah, Smit Alkesh; Green, Micah J; Cañas-Carrell, Jaclyn E


    Single-wall carbon nanotubes (SWNTs) are projected to increase in usage across many industries. Two studies were conducted using Zea L. (corn) seeds exposed to SWNT spiked soil for 40 d. In Study 1, corn was exposed to various SWNT concentrations (0, 10, and 100 mg/kg) with different functionalities (non-functionalized, OH-functionalized, or surfactant stabilized). A microwave induced heating method was used to determine SWNTs accumulated mostly in roots (0-24 μg/g), with minimal accumulation in stems and leaves (2-10 μg/g) with a limit of detection at 0.1 μg/g. Uptake was not functional group dependent. In Study 2, corn was exposed to 10 mg/kg SWNTs (non-functionalized or COOH-functionalized) under optimally grown or water deficit conditions. Plant physiological stress was determined by the measurement of photosynthetic rate throughout Study 2. No significant differences were seen between control and SWNT treatments. Considering the amount of SWNTs accumulated in corn roots, further studies are needed to address the potential for SWNTs to enter root crop species (i.e., carrots), which could present a significant pathway for human dietary exposure.

  8. Repairing and Strengthening of an Existing Reinforced Concrete Building: A North Cyprus Perspective

    Hakan Yalciner


    Full Text Available Problem statement: Inadequate attention during design and construction of some of Reinforced Concrete (RC buildings in North Cyprus has raised questions about the performance level of these existing buildings under future earthquakes. Approach: Column jacketing, adding steel braces and new shear walls to an existing building are common strengthening methods used by practical engineers in North Cyprus to increase the performance level of an existing building. Results: The aim of this study was to determine the most effective strengthening method among these three mentioned techniques. As a case study, a four stories RC existing building was selected and assessed using finite element method. To remodel of the existing building, the survey works done included three main steps, detecting the reinforcement bars for beams and columns, actual used concrete strength and soil type. The beams and columns reinforcement bars were determined using Ferro scan method and the soil was sampled in Girne city to determine the soil type. The actual concrete strength was determined using core test. Three common strengthening techniques mentioned above, were applied to the existing building. Then the efficiency of each strengthening method was investigated on the basis of removing of weak columns, not-safe beam-column joints in shear and performance levels based on the FEMA356 and Turkish earthquake code. Conclusion/Recommendations: Results showed that column jacketing is the most effective method to remove the weak columns and not-safe column-beam joints in shear. Nonlinear static pushover results showed that despite that adding shear walls caused an increase in the structural base shear and a reduction in the maximum roof displacement and the number of collapsed elements at FEMA356 performance point, but it caused a remarkable reduction in the building ductility ratio. Finally, results showed that the column jacketing is the most effective and the most economic

  9. On the application of plastic concrete cut-off wall in Huashan Reservoir Risk Removal Reinforcement Project%浅谈塑性混凝土防渗墙在花山水库除险加固工程中的应用

    劳正绍; 梁水新; 陆家辉


    Plastic concrete cut-off wall is a plastic wall structure with certain compressive strength and impermeability capacity,and lower modulus of elasticity,which can be controlled artificially for curbing leakage,piping,etc.Plastic concrete cut-off wall not only can cut off seepage flow of the dam (soil)body and lower seepage slope in the dam (soil) body,but also can withstand certain vertical and horizontal load.It can adapt to the surrounding dam (soil ) body deformation and foundation deformation,thereby greatly reducing stress in the wall,avoiding wall cracking,saving cement and reducing the cost of the engineering seepage control with remarkable effect.%塑性混凝土防渗墙是一种塑性墙体结构,具有一定的抗压强度和抗渗能力,有较低的弹性模量,并可人为地控制,抑制渗漏、管涌等。塑性混凝土防渗墙不仅能有效截断坝(土)体的渗透水流和降低坝(土)体中渗透坡降,还能承受一定的垂直和水平荷载,能适应周围坝(土)体变形、地基变形,大大减小墙体内应力,避免墙体开裂,且可节约水泥,降低工程防渗造价,效果显著。

  10. Engineered cementitious composites for strengthening masonry infilled reinforced concrete frames

    Dehghani, Ayoub; Nateghi-Alahi, Fariborz; Fischer, Gregor


    The results of the second part of a comprehensive experimental program, aimed at investigating the behavior of masonry infilled reinforced concrete (RC) frames strengthened with fiber reinforced engineered cementitious composites (ECC) used as an overlay on the masonry wall, are presented in this...... and energy absorption capacity of the infilled frame, prevent brittle failure modes in the infill wall, and provide a reasonable system overstrength....

  11. Analysis of reinforced concrete building according to the EC 8

    Dimec, Andrej


    In the Thesis the analysis and the software based design of the six-storey reinforced concrete wall building according to the European Standard Eurocode is presented. The structural system of the building consists of reinforced concrete walls. First the calculation of the self weight, variable actions, snow and the wind loads has been examined. The major part of the thesis deals with seismic analysis, which was performed by the modal analysis and simplified non-linear seismic a...

  12. Study status of vacuum preloading soft-soil foundation reinforcing theory and technology%真空预压软土地基加固理论和技术研究现状

    王成保; 苌宽; 张玉国


    The paper introduces basic working principles of vacuum preloading method,discusses research status of vacuum preloading soft-soil foundation reinforcing theory and construction technology,analyzes problems existing in vacuum preloading soft-soil foundation construction,and finally points out that:the combination of vacuum preloading technology,monitoring technology and information constructing technology will be good for realizing whole-process construction monitoring,so as to improve social and economic benefits of the project.%介绍了真空预压法的基本工作原理,论述了真空预压软土地基加固理论及施工工艺的研究现状,分析了真空预压软土地基施工中存在的问题,指出将真空预压工艺、监测技术与信息化施工技术相结合,有助于实现施工过程的全面监测,从而提高工程的社会经济效益.

  13. Basal Reinforced Piled Embankments

    Van Eekelen, S.J.M.


    A basal reinforced piled embankment consists of a reinforced embankment on a pile foundation. The reinforcement consists of one or more horizontal layers of geosynthetic reinforcement (GR) installed at the base of the embankment. The design of the GR is the subject of this thesis. A basal

  14. The Reinforcement Hierarchy

    Forness, Steven R.


    Reinforcement hierarchy implies movement along a continuum from top to bottom, from primitive levels of reinforcement to more sophisticated levels. Unless it is immediately obvious that a child cannot function without the use of lower-order reinforcers, we should approach him as though he responds to topmost reinforcers until he demonstrates…

  15. Study on Pile-soil Stress Ratio of Composite Foundation Reinforced with Geosynthetic Encased Stone Columns%筋箍碎石桩复合地基桩土应力比的计算与分析∗

    张玲; 陈哲; 赵明华


    针对筋箍碎石桩复合地基的受力变形特点,考虑桩土的初始应力状态,假定桩为具有恒定剪胀角的弹塑性体,且满足摩尔库伦屈服准则与非关联流动法则,土体和加筋体为线弹性材料,考虑桩筋材土三者间相互作用,导得了筋箍碎石桩复合地基桩土应力比计算新公式。为验证本文计算公式的可行性,将本文方法计算结果与弹塑性极限分析方法结果进行对比分析,两者吻合良好。在此基础上,分析探讨了筋材刚度、桩周土变形模量、面积置换率等因素对筋箍碎石桩复合地基桩土应力比的影响。分析结果表明:筋材刚度是桩土应力比的主要影响因素,桩土应力比随筋材刚度、面积置换率、桩体内摩擦角的增大而增大,随着桩周土变形模量和桩体剪胀角的增大而减小。%Based on the deformation characteristics of the composite foundation reinforced with encased stone columns under vertical loads,a new calculation formula to estimate the pile-soil stress ratio of geo-synthetic-encased stone columns was proposed with consideration of pile-geosynthetic-soil interactions.In the derivation process,initial stresses in soil and a column were taken into account,the column was con-sidered as an elastic-plastic material with constant dilatancy angle and satisfying both the Mohr-Coulomb yield criterion and non-associated flow rule,and the soil and geosynthetic encasement were considered as linear-elastic materials.The proposed formula was validated by comparison with the results of elasto-plas-tic limit analysis method.Finally,a parametric study was conducted to investigate various parameter effects of encasement stiffness,deformation modulus of soil,and replacement ratio on the behavior of the pile-soil stress ratio.The parametric study shows that the pile-soil stress ratio of the composite foundation with the encased stone column increases with the increase of encasement


    涂兵雄; 贾金青


    Analytical expressions for the active earth pressure ratio and active earth pressure are derived, against on a rigid retaining wall from clayey backfill undergoing horizontal translation) considering the soil arching effects and the influence of soil-wall friction angle, wall adhesion and cohesion of backfill. The results show that the active earth pressure ratio and active earth pressure are related to soil-wall friction angle, depth of the point and the internal friction angle, cohesion, unit weight of the backfill. The theoretical comparisons between the analytical expressions proposed for active earth pressure ratio and active earth pressure and the existing classical theory, the previous research results show great agreement with each other, so as to verity the correctness of the results in this paper.%以墙后填土为黏性土的刚性挡土墙为研究对象,考虑挡土墙后的土拱效应,以及墙土摩擦角、墙土黏结力、墙后填土黏聚力的影响,推导挡土墙在平动模式下的主动土压力系数和主动土压力解析解.结果表明,考虑土拱效应的主动土压力系数和主动土压力均与墙土摩擦角、计算点深度以及墙后填土的内摩擦角、黏聚力及重度有关.通过将求解的主动土压力系数和主动土压力与现有经典理论解及前人理论研究成果对比,发现结果完全吻合,验证该研究结果的正确性.

  17. Discussion of Reinforcement Meassures for Anti-sliding Anchor Pile-plank Wall and Negative Effects%某锚索抗滑桩板墙工程补强措施及负效应初探

    和曙泉; 徐国民


      介绍了高填方边坡治理工程补强措施,针对补强措施的负效应问题进行了力学分析,从岩土及工程力学角度探讨了负效应产生的原因,并就构件安全性及负效应的控制问题提出了个人见解。%  The paper introduced reinforcement measures for high fill slope control project.According to the negative effects of reinforcement measures, mechanical analysis was made;the causes of negative effects were discussed in geotechnical and engineering mechanics, the personal views on components safety and negative effects control were put forward.

  18. 考虑土拱效应的刚性挡墙主动土压力分析%Analysis of active earth pressure on rigid retaining walls considering soil arching

    王杰; 夏唐代; 贺鹏飞; 黄博


    以墙后填土为无黏性土的刚性挡土墙为研究对象,考虑墙后土体的土拱效应,修改了 Shubhra Geol 抛物线形土拱表达式,推导了对应不同内摩擦角和墙-土摩擦角的挡土墙平动模式下的主动土压力系数。基于水平微分单元法,得到考虑土拱效应的主动土压力分布、合力大小和合力作用点高度的理论表达式,并与现有经典理论解及前人理论研究成果和模型试验数据进行对比分析,结果表明,主动土压力与墙-土接触面摩擦角、土体内摩擦角、土体重度和挡墙高度相关,土压力分布为非线性,与其他结果比较吻合,从而验证了该研究成果的正确性。%Taking a rigid retaining wall with cohesionless backfill for example, considering the soil arching, the active earth pressure factor is derived for retaining wall under translation mode with different internal friction angles and wall-soil friction angles. The Shubhra Geol parabolic soil arching expression is modified. Based on horizontal differential element method, new formulations are proposed for calculating the active earth pressure, the resultant earth pressure and its action point. In order to check the accuracy of the proposed formulation, the predictions from the equation are compared with the results of full-scale test and existing classical theory. The results show that the active earth pressure is related to wall-soil friction angle, the internal friction angle, the unit weight of backfill and the height of retaining wall. It is shown that the earth pressure is nonlinear and the previous research results show great agreement with each other;and the correctness of the results is verified.

  19. Study on passive earth pressure acting on the embedment of an earth retaining wall for braced excavation work in cohesive soil; Nenseido jiban ni okeru kussaku dodomeheki neirebu no judo doatsu ni kansuru kenkyu

    Nakamura, H. [Pacific Consultants K.K., Tokyo (Japan); Hirashima, K. [Yamanashi University, Yamanashi (Japan). Faculty of Engineering


    Passive earth pressure exerts a great influence on the stress and deformation of earth retaining walls in braced excavation. To calculate this pressure, conventional ultimate earth pressure equation, or Rankine-Resals and Coulomb`s equation, are currently applied respectively to cohesive and sandy soil. However, these intentional equation to determine passive earth pressure do not adequately take into account the excavation width during work and the shearing resistance on the earth retaining wall surface. This paper deals with cohesive soil only, deriving a calculation equation for passive earth pressure, which takes into account excavation width and the shearing resistance of the earth retaining wall surface. Then, constants in this equation are determined using the calculation results obtained from the finite element method with blasts-plastic elements. The calculation results are also compared with measured values in the model test in order to check the applicability of the calculation equation for passive earth pressure thus obtained. Finally, this paper proposes a practicable calculation equation for passive earth pressure. 13 refs., 10 figs., 10 tabs.

  20. To detect anomalies in diaphragm walls

    Spruit, R.


    Diaphragm walls are potentially ideal retaining walls for deep excavations in densely built-up areas, as they cause no vibrations during their construction and provide structural elements with high strength and stiffness. In the recent past, however, several projects using diaphragm walls as soil an


    YAN Shuwang; ZHANG Xinqiang; LIU Run


    An FE analysis procedure was presented to predict the behavior of soil-geogrid interaction under automobile loading. The dynamic interactions between the transverse bars, the longitudinal ribs and the soil were simulated by a system consisting of nonlinear springs, dashpots and masses, to study the deformation properties of the reinforced soil. The equivalent stiffness and damping ratios could be determined with the shaking table. The dynamic responses of a reinforced subgrade were analyzed with the 3D finite element approach. This approach is programmed and applied to analyze the soil-geogrid interaction under dynamic loading. The comparative analysis of the response of the reinforced subgrade and that of the subgrade without reinforcement shows that the geogrid placed at the bottom of the base layer may effectively reduce the accumulative plastic deformation due to the cyclic automobile loading.

  2. Review of research on characteristics of seepage-induced consolidation of soil under negative-pressure reinforcement conditions%负压条件下土体渗流固结特性研究综述

    李平; 金奕潼; 赖建英; 刘伟


    This paper presents a review of literature related to project failures, variations of groundwater level, seepage characteristics of soil bodies, and mechanisms of seepage-induced consolidation during the reinforcement process under vacuum negative pressures. Although the seepage-induced vacuum consolidation method has been widely applied, theoretical study of the method lags far behind its practical application and still involves some disputes. Some key issues for future research regarding the method are presented, including new technology for measurement of groundwater levels under negative pressures, mechanisms of seepage-induced consolidation of soil, the effective transmission range of the vacuum degree, and the variation regularity of the zero-pressure surface.%针对真空负压加固过程中引起的工程破坏、地下水位变化规律、土体渗流特性、渗流固结机理等问题进行了分析,发现这种方法虽已得到广泛的应用,但其理论研究远落后于工程实践,并存在很多争议。指出今后需要研究的关键工作,如负压状态下地下水位测试新技术、土体渗流固结作用机理、真空度有效传递范围、“0”压面变化规律等。

  3. Modeling of geosynthetic reinforced capping systems

    Viswanadham, B.V.S.; Koenig, D.; Jessberger, H.L. [Univ. of Bochum (Germany)


    The investigation deals with the influence of a geosynthetic reinforcement on the deformation behavior and sealing efficiency of the reinforced mineral sealing layer at the onset of non-uniform settlements. The research program is mainly concentrated in studying the influence of reinforcement inclusion in restraining cracks and crack propagation due to soil-geosynthetic bond efficiency. Centrifuge model tests are conducted in the 500 gt capacity balanced beam Bochum geotechnical Centrifuge (Z1) simulating a differential deformation of a mineral sealing layer of a landfill with the help of trap-door arrangement. By comparing the performance of the deformed mineral sealing layer with and without geogrid, the reinforcement ability of the geogrid in controlling the crack propagation and permeability of the mineral swing layer is evaluated.

  4. 广珠城际铁路简支箱梁梁端半隔墙补强加固试验分析%Experimental Analysis on Semi-partition Wall Reinforcement in the End of Simply Supported Box Beam on Guangzhou-Zhuhai Intercity Railway



    It is found during erection of the simply-supported double-cell box beam on Guangzhou-Zhuhai Intercity Railway that under the effect of loads, cracks occurred between the bottom base and web plate in beam-ends and extended along longitudinal direction caused by the erection position of bridge. For this phenomenon, semi-partition wall is set up in the section of beam-ends for reinforcing measures. Through solid beam static load and beam-end load test, the effect of reinforcement is verified very well in engineering practice.%广珠城际铁路单箱双室简支箱梁,在架设过程中发现,受支座横桥向设置位置等因素影响,在架梁荷载作用下,梁端底板支座与腹板间部位出现裂缝,并沿梁体纵向有一定延伸.针对这一现象,采用梁端截面设半隔墙补强措施进行处理.通过实体梁静载及架梁梁端荷载试验与工程实践验证,加固效果良好.

  5. Analysis on the Reinforcement of Soft Soil Subgrade by Using Vibro-replacement Stone Column in Expressway Construction%高速公路工程软土路基应用振冲碎石桩加固分析

    邓强; 肖莹


    高速公路对路基沉降的要求很高,选择正确的地基处理方式直接关系到工程质量、投资和进度。本文对振冲碎石桩设计方法、施工工艺以及工程质量控制等进行了研究,并给出了振冲碎石桩在京珠高速公路软土路基加固中的应用实例。%Expressway has high requirements on the roadbed settlement, the right selection of foundation treatment way is directly related to the quality, investment and progress of the construction. This paper studies the design methods, construction technology and construction quality control of vibro-replacement stone column, and puts forward the application examples of vibro-replacement stone column of the soft soil subgrade reinforcement in Jingzhu Expressway.

  6. 砌体结构外套预制钢筋混凝土墙板加固及隔震加层振动台试验研究%Shaking table test of masonry structures strengthened with external prefabricated reinforced concrete wall and with added story isolation

    王曙光; 苗启松; 刘金龙; 刘伟庆; 杜东升


    为研究砌体结构外套预制钢筋混凝土墙板加固技术的加固效果,并探讨在其顶部隔震加层的可行性,进行了3个相似比为1/4模型的振动台对比试验,模型分别是加固砌体结构模型、加固后加层非隔震结构模型和加固后加层隔震结构模型。试验测试了模型结构的动力特性及其在不同地震作用下的动力响应,为了分析结构震损后的动力响应,在试验模型经历罕遇地震作用下的损伤后又继续进行不同水准地震输入试验。试验结果表明:加层非隔震结构的上部钢框架鞭稍效应非常明显;加层隔震结构有效延长了结构自振周期,增大了结构阻尼比。加层隔震结构既有效降低了下部砌体结构的地震响应又降低了上部钢框架的地震响应,其加固效果和抗震性能优越。同时,震损后加层隔震结构的隔震效果明显降低,下部砌体的加速度反应可能大于加固结构和加层非隔震结构,建议在设计时充分考虑这种不利影响。%In order to research the reinforcement effects on masonry structure strengthened with external prefabricated reinforced concrete wall and investigate the possibility of added story isolation on the top of reinforced masonry structure, the shaking table tests of three 1/4. scaled models were conducted. These three models were reinforced masonry structure model, reinforced masonry structure with added story model and reinforced masonry structure with added story isolation model. The dynamic characteristics and seismic response of models were evaluated under different levels of earthquakes. And then, the models subjected to rare seismic cases were tested again to analyze the dynamic responses of damaged structures. The results indicate that added story isolation structure can prolong the structural vibration periods efficiently and increase the damping ratio. Whiplash effect of superstructure of added story non- isolation structure is very

  7. Experimental investigation of geogrid-reinforced and pile-supported embankment on soils with medium-low compressibility%中低压缩性土地区桩承式加筋路堤现场试验研究

    郑俊杰; 曹文昭; 董同新; 张军; 谢明星


    将桩承式加筋路堤技术应用于中低压缩性土地区高速铁路桥台和涵洞之间填方路基的处理,通过逐渐改变CFG桩桩长形成刚度均匀变化的地基加固区,严格控制线路纵向差异沉降.通过现场试验对桥台、涵顶和路基中心地基沉降进行了长期观测,同时对桩承式加筋路堤桩间土沉降、孔隙水压力、格栅上下表面土压力和格栅变形进行了长期监测分析.研究结果表明:桩承式加筋路堤可有效减小中低压缩性土地基沉降,总沉降小且很快趋于稳定;桩承式加筋路堤通过土拱效应和张拉膜效应将路堤荷载向桩帽传递,格栅下桩土应力比明显高于格栅上,张拉膜效应明显,格栅上桩土应力比接近1.0,土拱效应较弱;格栅在路肩处发挥的作用强于线路中心处.%The geogrid-reinforced and pile-supported embankment is adopted to treat the subgrade of high-speed railways between the bridge abutment and culvert on the soils with medium-low compressibility. The subgrade with uniformly variable stiffness is formed by varying the lengths of CFG piles gradually aiming at controlling the longitudinal differential settlement strictly. The settlements of bridge abutment, culvert and subgrade center are monitored based on full scale field tests. Meanwhile, the settlement of the surrounding soils of pile, the pore water pressure, the earth pressure above/below the geogrid, and the geogrid deformation are measured. The experimental results demonstrate that the total and layered settlements of the subsoils with medium-low compressibility are reduced effectively, and the total settlements are very small and reach the stable value soon. The embankment load is transferred to pile caps by the combined action of soil arching effect and tensioned membrane effect. The pile-soil pressure ratio below the geogrid is significantly larger than that above the geogrid, which suggests that an obvious tensioned membrane effect exists

  8. 大直径SMW工法设计与施工关键技术分析%Analysis of the Design and Construction Techniques for Soil Mixing Wall (SMW) with Large Diameter



    深基坑支护设计,不仅要保证基坑内的正常作业,而且要防止基坑及坑外土体的移动,确保基坑附近建筑物、道路、管线等的正常使用.因此,深基坑围护结构的安全性显得尤为重要.在众多围护方法中,SMW工法(型钢水泥土搅拌墙)以其适用性强、围护成本低、施工周期短而倍受关注.文章结合工程实践,对大直径SMW工法在软土地基深基坑支护中的支护结构设计及施工要点及难点进行了分析和探讨.%It is a key point for the security of deep foundation pit enclosure structure in the design of deep foundation pit support which guarantees the normal construction of foundation pit and prevents from soil mass movement inside and outside the pit in order to keep the normality of buildings,roads and pipelines nearby.Special attention was given to the soil mixing wall featuring good applicability,low construction cost and short construction period.Based on the construction practice,some discussions of the key techniques in the design and construction were made regarding the application of soil mixing wall with a large diameter to deep foundation pit in soft soil.


    周亦涛; 陈福全


    The stresses on the wall and sliding plane of the sliding backfill mass at arbitrary depths were obtained according to the soil arching effect. A formula of the seismic active failure angle behind the non-vertical rigid retaining wall under translation mode was obtained on the basis of the pseudo-static method and the equilibrium total forces. A formula of the seismic active earth pressure against the non-vertical rigid retaining wall under translation mode was derived according to the method of differential level layer. The seismic active earth force and the action point were obtained. The distribution of seismic active earth pressure from the proposed formula was non-linear along the height of wall. In addition,the influences of the wall-back inclination,internal friction angle of backfill,wall-soil friction angle,seismic coefficient and load against the backfill surface on the seismic failure angle,seismic active earth pressure and its coefficient,seismic active earth force and height of its application were investigated.%由土拱效应原理得到滑裂土体的墙面和滑裂面上的应力,然后根据拟静力法和滑裂土体的整体受力平衡,得到平移模式下非垂直刚性挡土墙的地震主动破裂角计算式.进一步根据水平层分法获得墙背地震主动土压力及其系数、地震主动土压力合力及其作用点高度等的计算式.此外,分别讨论墙背倾角、填土内摩擦角、墙土摩擦角、地震系数和填土表面荷载等对地震主动破裂角、法向地震主动土压力分析、地震主动土压力合力系数、地震主动土压力合力及其作用点相对高度等的影响.

  10. Management of Reinforcement Corrosion

    Küter, André; Geiker, Mette Rica; Møller, Per

    Reinforcement corrosion is the most important cause for deterioration of reinforced concrete structures, both with regard to costs and consequences. Thermodynamically consistent descriptions of corrosion mechanisms are expected to allow the development of innovative concepts for the management...... of reinforcement corrosion....

  11. Partial Planning Reinforcement Learning


    This project explored several problems in the areas of reinforcement learning , probabilistic planning, and transfer learning. In particular, it...studied Bayesian Optimization for model-based and model-free reinforcement learning , transfer in the context of model-free reinforcement learning based on

  12. Variable Resolution Reinforcement Learning.


    Can reinforcement learning ever become a practical method for real control problems? This paper begins by reviewing three reinforcement learning algorithms... reinforcement learning . In addition to exploring state space, and developing a control policy to achieve a task, partigame also learns a kd-tree partitioning of

  13. Influence of diaphragm wall installation in overconsolidated sandy clays on in situ stress disturbance and resulting wall deformations

    Truty Andrzej Adam


    Full Text Available Numerical modeling of deep excavations becomes a standard practice in modern geotechnical engineering. A detailed numerical model for a given case is able to reproduce major effects of soil-structure interaction by taking into account any kind of drainage conditions, strong stiffness variation due to effective stress and strain changes, creep and cracking, when reinforced concrete is used as a structural material, but also interface effects between subsoil and structure. Calibrating soil constitutive models is one of the most difficult tasks and due to several sources of uncertainty there is no one unique set of the data that should be used in numerical predictions. Lack or incompleteness of experimental data, significant mismatch between laboratory and field tests is an another source of difficulty. Contrary to several simplified methods, that are usually limited to two dimensions, numerical models allow a full 3D analysis in which many simplifications can be eliminated. This paper is devoted to the problem of in situ stress disturbance caused by diaphragm wall installation in overconsolidated quaternary sandy clays and its influence on final wall deformations.

  14. Retrofitting Masonry Walls with Carbon Mesh

    Patrick Bischof


    Full Text Available Static-cyclic shear load tests and tensile tests on retrofitted masonry walls were conducted at UAS Fribourg for an evaluation of the newly developed retrofitting system, the S&P ARMO-System. This retrofitting system consists of a composite of carbon mesh embedded in a specially adapted high quality spray mortar. It can be applied with established construction techniques using traditional construction materials. The experimental study has shown that masonry walls reinforced by this retrofitting system reach a similar strength and a higher ductility than retrofits by means of bonded carbon fiber reinforced polymer sheets. Hence, the retrofitting system using carbon fiber meshes embedded in a high quality mortar constitutes a good option for static or seismic retrofits or reinforcements for masonry walls. However, the experimental studies also revealed that the mechanical anchorage of carbon mesh may be delicate depending on its design.

  15. Displacement ductility for seismic design of RC walls for low-rise housing

    Carrillo,Julian; González, Giovanni; Rubiano, Astrid


    The paper compares and discusses displacement ductility ratios of reinforced concrete walls typically used in one- and two-story houses. Ductility is investigated by assessing response measured on 39 walls tested under shaking table excitations and quasi-static lateral loads. Variables studied were the height-to-length ratio and walls with openings, type of concrete and, steel ratio and type of web reinforcement. An equation to estimate the available ductility of a wall is proposed. Based on ...

  16. Wonderful Walls

    Greenman, Jim


    In this article, the author emphasizes the importance of "working" walls in children's programs. Children's programs need "working" walls (and ceilings and floors) which can be put to use for communication, display, storage, and activity space. The furnishings also work, or don't work, for the program in another sense: in aggregate, they serve as…

  17. Ambiguous walls

    Mody, Astrid


    The introduction of Light Emitting Diodes (LEDs) in the built environment has encouraged myriad applications, often embedded in surfaces as an integrated part of the architecture. Thus the wall as responsive luminous skin is becoming, if not common, at least familiar. Taking into account how wall...

  18. Experimental study of soil arching of geogrid-reinforced and pile-supported widening embankment%桩-网加固拓宽路堤土拱效应试验研究

    吕伟华; 缪林昌; 王非; 蔡海粟; 张成相


    Soil arching is very important for analyzing the stress state of existing and widening embankment and differential settlement between piles (caps) and subsoil. In this paper, the behavior of soil arching is analyzed for a widening embankment which is supported by rigid piles with caps and reinforced by geogrid. Based on the test site of the widening expressway project, earth pressures on caps and subsoil at the bottom and at different depths to fill surface are investigated; and tensile strains of the geogrid are monitored too. Then stress concentration ratios and soil arching ratios are analyzed and compared with several current design methods, including the Guido method, the BS8006 method, the Kempfert method and the Low method. Results show that, a two-dimensional plane soil arching fill load distribution on caps and subsoil within a critical arch height which is deduced to be 2.0 m owing a ratio of 1.4 the pile clear spacing, and is consistent with BS8006. The Guido and BS8006 methods were too conservative on assessing tensile strain of geogrid; Except for the Guido method, all rest presented design methods underestimated the resistance from the compressible subsoil. So, further study and a better understanding of soil arching should be developed.%  采用桩-网加固拓宽路堤时,土拱效应对于分析新老路堤应力分布和差异沉降有至关重要的作用。依托某高速公路路堤拓宽项目对土拱效应进行研究,对试验段新路堤填筑过程及运营时基底桩及桩间土不同位置处土压力、加筋层拉应变进行监测,得到二维平面土拱效应的变化规律,并利用已有土拱效应计算方法对现场实测结果进行对比验证。结果表明,平面土拱作用范围在一定高度范围内,试验段约为2.0 m,即拱高、拱跨之比约为1.4,与英国规范 BS8006[1]相近;按 Guido 法[2]与 BS8006法[3]进行土工格栅的设计均过于保守,除 Guido 法以外,几种方

  19. 临近地下室外墙影响下的考虑土拱效应的挡土墙主动土压力研究%Research on active earth pressure behind retaining wall adjacent to existing basements exterior wall considering soil arching effects

    赵琦; 朱建明


    It was necessary to use the adaptive theory for computing the distribution of earth pressure behind the wall adjacent to existing basements and the height of total earth pressure, because it was inconsistent with the Rankine’s theory which was based on the semi-infinite half space state. It could be divided two parts of the deformation trends by considering soil arching effect. The upper soil parts slide down alongside the wall which is same with Terzaghi’s tarp door experiment. Also, the lower soil parts slide down as a triangle the soil wedge. So it is reliable that the earth pressure behind the retaining wall adjacent to existing basement should be analyzed based on the above deformation trends of the upper part and lower part. Assuming the arch in soil arching as circular, the lateral coefficients of earth pressure of retaining wall about both upper and lower parts are derived from the principal stress rotation. And the formula of distribution of lateral active earth pressure is given based on the soil static wedge equilibrium. Expressions of the total earth pressure and the height of acting point are derived by translation of coordinates. According to the examples, the results by proposed method are close to the simulation results. So it has a significant meaning for active earth pressure theory which considering the soil arching effect.%当挡土墙附近存在临近建筑地下室外墙时,其挡土墙土压力与传统的Rankine理论基于无限半空间体假定不符,因而在这种新的工程背景下需要采用合适的理论来计算挡土墙土压力及其作用点高度。已有的研究表明,这种条件下土体的变形趋势可分为上、下两大部分:上部土体变形类似于Terzaghi的活动门试验,土体沿着墙体下滑,而下部土体则沿着土楔形体而变形。因而将土拱效应用于求解挡土墙土压力的计算分成了上、下两大部分考虑。假定土拱形状为圆弧,基于主应力旋

  20. Habituation of reinforcer effectiveness

    David R Lloyd


    Full Text Available In this paper we propose an integrative model of habituation of reinforcer effectiveness (HRE that links behavioral and neural based explanations of reinforcement. We argue that habituation of reinforcer effectiveness (HRE is a fundamental property of reinforcing stimuli. Most reinforcement models implicitly suggest that the effectiveness of a reinforcer is stable across repeated presentations. In contrast, an HRE approach predicts decreased effectiveness due to repeated presentation. We argue that repeated presentation of reinforcing stimuli decreases their effectiveness and that these decreases are described by the behavioral characteristics of habituation (McSweeney and Murphy, 2009;Rankin et al., 2009. We describe a neural model that postulates a positive association between dopamine neurotransmission and HRE. We present evidence that stimulant drugs, which artificially increase dopamine neurotransmission, disrupt (slow normally occurring HRE and also provide evidence that stimulant drugs have differential effects on operant responding maintained by reinforcers with rapid vs. slow HRE rates. We hypothesize that abnormal HRE due to genetic and/or environmental factors may underlie some behavioral disorders. For example, recent research indicates that slow-HRE is predictive of obesity. In contrast ADHD may reflect ‘accelerated-HRE’. Consideration of HRE is important for the development of effective reinforcement based treatments. Finally, we point out that most of the reinforcing stimuli that regulate daily behavior are non-consumable environmental/social reinforcers which have rapid-HRE. The almost exclusive use of consumable reinforcers with slow-HRE in pre-clinical studies with animals may have caused the importance of HRE to be overlooked. Further study of reinforcing stimuli with rapid-HRE is needed in order to understand how habituation and reinforcement interact and regulate behavior.

  1. 深埋黏土层冻结壁厚度的有限段高计算模型研究%Research on finite-length computational model of deep-buried frozen soil wall thickness

    黄俐; 宋常军


    冻结壁设计理论关系到冻结法施工的成败,常规的弹塑性力学冻结壁厚度模型已不适用于深厚冲积层中冻结壁的设计。考虑卸载状态下冻结壁-周围未冻土的共同作用,基于三向应力状态下的冻土流变理论及偏张量虎克定律,建立了深埋黏土层有限段高冻结壁的变形及厚度计算模型。结合立井冻结工程,探讨了该计算模型对不同开挖因素的响应程度。结果表明:合理的降低段高、控制施工速度对冻结法凿井安全至关重要。该计算模型对深埋黏土层冻结壁设计有重要的理论意义。%As the design theory of frozen wall is the key of artificially ground freezing construction, and the conventional elastic-plastic mechanical models are not suitable for frozen wall design in deep alluvium. Considering the effect of excavation length and the interaction between frozen soil wall and its surrounding earth mass, the calculation models of deformation and thickness of finite-length frozen soil wall are developed based on the rheological theory of frozen soil and Hooke′s law of deviatoric tensor of equivalent stress-equivalent strain under tri-axial stress state. Combined with a shaft freezing engineering case, the influences of excavation length and duration of exposure on the calculation models are discussed. The results show that reducing the excavation section appropriately and controlling the construction speed reasonable is crucial to the safety of artificial freezing shaft sinking project.

  2. FRP strengthening of RC walls with openings

    Hansen, Christian Skodborg; Sas, Gabriel; Täljsten, Björn


    Strengthening reinforced concrete (RC) walls with openings using fibre reinforced polymers (FRP) has been experimentally proven to be a viable rehabilitation method. However, very few theoretical investigations are reported. In this paper two methods of analysis are presented. Since openings vary...... in size, the analysis of a strengthened wall can be divided into frame idealization method for large openings, and combined disk and frame analysis for smaller openings. The first method provides an easy to use tool in practical engineering, where the latter describes the principles of a ductile...

  3. Plasticity Approach to HSC Shear Wall Design

    Liu, Lunying; Nielsen, Mogens Peter


    The paper describes a simple theory for determining the ultimate strength of shear walls. It is based on application of the theory of perfectly plastic materials. When applied to concrete the theoretical solutions must be modified by inserting into the solutions a reduced compressive strength...... to 140 MPa and reinforcement yield strengths up to 1420 MPa. The work was carried out as a Ph.D. study by the first author, the second author supervising the study.Keywords: shear wall, plasticity, strut and tie, load-carrying capacity, concrete, reinforcement....

  4. Review on Stabilization of Soil Using Coir Fiber



    Full Text Available Soil stabilization has become a major issue in construction engineering and the researches regarding the effectiveness of using natural wastes are rapidly increasing. The use of natural fibers to reinforce soil is an old and ancient idea. Consequently, randomly distributed fiber reinforced soils have recently attracted increasing attention in geotechnical engineering. The main aim of this paper, therefore, is to review the, benefits, properties and applications of coir fiber in soil reinforcement through reference to published scientific data


    Yasuhara, Kazuya; Yamazaki, Shinji; Sakakibara, Tsutomu

    Advantageous aspects of sandwich-type reinforced earth structures combined with geosynthetics and sand mat are highlighted in this paper. Those aspects were elucidated by two kinds of laboratory tests : (1) large consolidation tests for improvement of hydraulic conductivity and (2) model footing tests on improvement of bearing capacity and deformation characteristics for reinforced earth structures, including both vertical permeability and horizontal transmissibility characteristics of geosynthetics results from both laboratory tests indicated the following: i) Hydraulic conductivity of geosynthetics used for this type of earth reinforcement can be maintained for a long period. Such conductivity sometimes disappears, particularly because of clogging when geosynthetics are adopted in embankment construction using fine-grained soils. This fact indicates that the sand mats which are laid above and beneath geosynthetics play a salient role in preventing clogging of geosynthetics that occurs by intrusion of fines from cohesive soils. ii) Sandwich-type reinforcement combined with geosynthetics and sand mats increases stability and decreases deformation of earth structures. In particular, the sandwich structure is effective for providing toughness, which has remained an important issue for reducing infrastructural maintenance and costs. In the later part of the paper, conventionally available stability analysis was carried out to propose the design procedure for reinforced earth structures and at the same time numerical analysis was also conducted to ensure the applicability of the hybrid-sandwiched earth reinforcement newly proposed in the current paper. Finally, based on the horizontal placement by means of HBS described in the current paper, the vertical drain procedure using the sandwich structures for accelerating consolidation and increasing stability of soft soils is also suggested for the future research and investigation.

  6. Passive earth pressure on retaining walls calculated by principle of soil arching effect%基于土拱效应原理求解挡土墙被动土压力

    侯键; 夏唐代; 孔祥冰; 孙苗苗


    In the translational displacement mode, a stress of wedge soil between rigid retaining wall and sliding surface, which is in the passive state of limit equilibrium, is analyzed. Considering the horizontal equilibrium of the soil between the wall and the slip surface, the formula of passive earth pressure coefficient and the angle of failure line to horizontal are obtained by using the principle of soil arching effect. According to the equilibrium equation considering the static equilibrium conditions of horizontal unit of soil, the formula of the passive earth pressure distribution, the resultant earth pressure and the application point of resultant earth pressure on retaining wall are respectively set up. After comparing the computed result using the method mentioned above with the experiment results and the results obtained on the basis of Coulomb and Rankine theories, it is demonstrated that the calculating results agree well with the experimental results; and thus the calculating method obtained is verified rational.%对平移模式下的刚性挡土墙和滑裂面间的楔形土体处于被动极限平衡状态的应力进行分析,考虑墙面和滑裂面之间土体水平力平衡,运用土拱效应原理推导出被动土压力系数和滑裂面水平倾角.并根据水平单元土体的静力平衡条件建立平衡方程,提出被动土压力分布、土压力合力及其作用位置的公式.将公式计算结果与试验结果以及库仑、朗肯理论所得结果进行比较,结果表明,与试验结果接近,验证了所得计算方法的合理性.

  7. Non-Linear Static Analysis of G+6 Storeyed RC Buildings with Openings in Infill Walls

    Praveen Rathod


    Full Text Available Masonry infill walls are commonly used in the RC frame structure buildings. Openings are inevitable part of the infill walls. Openings in infill walls significantly decrease the lateral strength and stiffness of RC frames. In the present study two-dimensional seven storeyed reinforced concrete (RC building models are considered with of (5%, 25%, and 35% openings Bare frame and soft storey buildings are modeled considering special moment resisting frame (SMRF for medium soil profile and zone III. Concrete block infill walls are modeled as pin-jointed single equivalent diagonal strut. Pushover analysis is carried out for both default and user defined hinge properties as per FEMA 440 guidelines using SAP2000 software. Results of default and user defined hinge properties are studied by pushover analysis. The results of ductility ratio, safety ratio, global stiffness, and hinge status at performance point are compared with the models. Authors conclude that as the percentage of openings increases, vulnerability increases in the infill walls. The user-defined hinge model is better than the default-hinge model in reflecting nonlinear behavior. The misuse of default-hinge properties may lead to unreasonable displacement capacities for existing structures. However, if the default-hinge model is preferred due to simplicity, the user should be aware of what is provided in the program and should avoid the misuse of default-hinge properties.

  8. Caracterização mecânica de laminados cimentíceos esbeltos reforçados com fibras de sisal Mechanical characterization of cement-based thin-walled laminates reinforced with sisal fibre

    Paulo R. L. Lima


    Full Text Available Com a proibição progressiva do uso de fibras de asbesto na fabricação de laminados à base de cimento, novos produtos têm sido desenvolvidos para suprir esta demanda do setor construtivo. A utilização de fibras de sisal como substituto ao asbesto, além de ser uma proposta ecológica tem grande importância socioeconômica, pois agregará valor a um produto cultivado com sucesso no semi-árido nordestino. Produziram-se, neste trabalho, placas laminadas com matriz de argamassa reforçadas com fibras longas de sisal. Ensaios de flexão em três pontos foram realizados com o objetivo de se estudar a influência da adição de fibras (3%, do número de camadas (2 e 3, da orientação das camadas (0 e 90° e da pressão de moldagem (0 e 2 MPa sobre o comportamento à flexão dos laminados. Os resultados indicam que a adição de fibras de sisal aumentou, para todos os casos estudados, a capacidade de absorver energia, a resistência à flexão pós-fissuração e a deflexão última do material. Os laminados reforçados com 3% de fibras de sisal, distribuídas em três camadas ortogonais à direção do carregamento e submetidos à pressão de moldagem de 2 MPa, apresentaram o melhor comportamento mecânico.Because of hazards to human and animal health, the use of asbestos and its products is being prohibited all around the world and academic institutions and fibre cement producers have been engaged in intensive research to find asbestos-free cement products. The application of natural fibres such as sisal to replace asbestos fibres can bring economical and ecological benefits due to their availability, low cost, low consumption of energy and suitability to the semi-arid area of the Northeast of Brazil (where not many plants can grow. In this paper, cement-based laminates reinforced with continuous sisal fibre were produced. Three point bending tests were carried out to evaluate the influence of addition of fibre (3%, number of layers of

  9. An Investigation on Axial Deformation Behavior of Thin-Wall Unfilled and Filled Tube with Aluminum Alloy (Al-Si7Mg) Foam Reinforced with SiC Particles

    Kumaraswamidhas, L. A.; Rajak, Dipen Kumar; Das, S.


    The objective of this research is to produce superior quality aluminum alloy foam with low relative density and higher resistance against compression deformation. This investigation has studied crash energy capacities of unfilled and filled aluminum alloy foams in mild steel tubes. The foam has been prepared by the melt route process with an addition of 5wt.% silicon carbide particles. The fabricated aluminum alloy foams were characterized by field emission scanning electron microscopy, x-ray diffraction, Fourier transform infrared spectroscopy, and Material Pro analyzer. It was observed that the foam-filled tubes could absorb more energy as compared to the unfilled tubes before reaching the complete densification point. Also, the aluminum alloy foams had better energy absorption capacity during the crash or impact loading. This article demonstrates the excellent ability of aluminum alloy foam application in the field where there is a need to absorb crash energy. It is to be noted that the amount of energy absorption will be greater for low-density foam filled in thin-wall rectangular section tubes. We have seen an increasing trend in the application of aluminum foams inside the thin-wall mild steel tubes for maximum energy absorption.

  10. Analysis of Facing Earth Pressure of Soil-nailing Wall on Double-parameter Foundation%双参数地基上土钉墙面层土压力计算

    王立峰; 祝江鸿


    土钉墙面层承受部分土(水)压力,文中把土钉墙面层看作是弹性地基上的有限长梁,在试验的基础上,推导了基于双参数地基的成层土层分布的土钉墙面层在土钉拉力作用下的挠曲线、转角、弯矩和剪力方程,并与实测数据进行了比较分析,验证了模型的合理性,得到的解析解基本上可以反映土钉墙面层土压力的分布.在此基础上,探讨了不同土性土层中土钉墙面层土压力的分布.面层土压力在土层的分界面上位移连续土压力突变;作用在软弱土层的面层土压力比硬土层上的面层土压力大;上软下硬型较上硬下软的土层分布更能使面层土压力得到充分发挥;同时文中计算了面层土压力换算成荷载与土钉拉力的比值,面层对于土压力的作用随着深度的增加表现得愈加明显,提出针对不同地区不同深度和不同土性条件下应给出比值的建议值,以使土钉墙的设计更符合其真实的作用机理.文中得到的结论和计算方法对于进一步研究土钉墙的作用机理及设计中如何充分发挥面层的作用等具有重要的理论意义和实际应用价值.%Present designers of soil-nailing walls consider the facing as accessory structure rather than the main one. However It is absolutely sure that the facing bear against water and earth pressure. Facing isolated and considered as finite beam on elastic foundation simply .solutions of displacement ^angles of rotation,bending moment and shear force of soil-nailing walls are gained on basis of field tests in layered soil. Rationality of the model is tested and verified. The results that can disclose laws of distribution of facing earth pressure are in agreement with the actual measurement datum. Earth pressure in bounding surface shows abrupt changes while displacement of facing exhibits continuous characteristics. Earth pressure of facing applied by soft soil presents bigger values than that of

  11. Thermal conductivity of reinforced soils:A literature review

    Muge Elif Orakoglu; JianKun Liu



  12. Seismic displacement of gravity retaining walls

    Kamal Mohamed Hafez Ismail Ibrahim


    Full Text Available Seismic displacement of gravity walls had been studied using conventional static methods for controlled displacement design. In this study plain strain numerical analysis is performed using Plaxis dynamic program where prescribed displacement is applied at the bottom boundary of the soil to simulate the applied seismic load. Constrained absorbent side boundaries are introduced to prevent any wave reflection. The studied soil is chosen dense granular sand and modeled as elasto-plastic material according to Mohr–Column criteria while the gravity wall is assumed elastic. By comparing the resulted seismic wall displacements calculated by numerical analysis for six historical ground motions with that calculated by the pseudo-static method, it is found that numerical seismic displacements are either equal to or greater than corresponding pseudo-static values. Permissible seismic wall displacement calculated by AASHTO can be used for empirical estimation of seismic displacement. It is also found that seismic wall displacement is directly proportional with the positive angle of inclination of the back surface of the wall, soil flexibility and with the earthquake maximum ground acceleration. Seismic wall sliding is dominant and rotation is negligible for rigid walls when the ratio between the wall height and the foundation width is less than 1.4, while for greater ratios the wall becomes more flexible and rotation (rocking increases till the ratio reaches 1.8 where overturning is susceptible to take place. Cumulative seismic wall rotation increases with dynamic time and tends to be constant at the end of earthquake.

  13. Experiment and calculation on seismic behavior of RC composite core walls with concealed steel truss

    Wanlin CAO; Weihua CHANG; Changjun ZHAO; Jianwei ZHANG


    To improve the seismic performance of reinforced concrete core walls, reinforced concrete com-posite core walls with concealed steel truss were proposed and systemically investigated. Two 1/6 scale core wall specimens, including a normal reinforced concrete core wall and a reinforced concrete composite core wall with concealed steel truss, were designed. The experimental study on seismic performance under cyclic loading was carried out. The load-carrying capacity, stiffness, ductility,hysteretic behavior and energy dissipation of the core walls were discussed. The test results showed that the seismic performance of core walls is improved greatly by the concealed steel truss. The calculated results were found to agree well with the actual measured ones.

  14. 基于有限元分析的日光温室土质墙体温度场模拟与验证%Simulation and Verification of Greenhouse Soil Wall Temperature Field by FEM Analysis

    侯加林; 王涛; 蒋韬; 王秀峰


    It was significant to study the temperature gradient and its change rule for evaluation of heat prevention performance , design and construction of greenhouse wall .The temperature data of greenhouse soil wall in Taian region were measured through multi -point temperature test instrument from December 2012 to February 2013 .The measured results coincided with that obtained through ANSYS FEM simulation .The fur-ther simulation results showed that the temperature of heat release and absorption layer in the wall changed pe -riodically in a day , while that of heat preservation and insulation layer changed smaller .The temperature at the wall bottom was higher , and changed a little in the horizontal direction , which was stable at 10~14℃for long time.The temperature was the highest at the place 0.2 m away from the inner surface of wall , and re-duced gently along the direction of wall thickness; the outer surface of the wall had the lowest temperature . Based on the simulated and measured results , the optimized soil wall of greenhouse in Taian area showed that the minimum thickness should be 2.2 m, including 0~0.5 m of heat release and absorption layer and 1.3~1 .7 m of heat preservation and insulation layer .%研究日光温室墙体中温度梯度及其变化规律对于日光温室墙体的蓄热保温性能分析评价、设计与建造有着重要的意义。2012年12月至2013年2月,采用自制多点温度测试仪,对山东泰安地区日光温室土质墙体的温度进行采集,并与ANSYS有限元模拟结果进行比较,发现温度场实测结果与模拟结果相吻合。进一步模拟结果表明,墙体蓄热/放热层一天中呈周期性变化,保温隔热层随外界温度变化较小,墙体下部温度较高,且在水平方向上温度梯度变化较小,在10~14℃持续时间长且稳定;距墙体内表面0.2 m处温度最高,并沿墙体厚度方向逐渐平缓降低,墙体外表面温度最低。基于模拟结

  15. 考虑土拱效应的铁路刚性挡墙主动土压力计算方法%Calculation Method of Active Earth Pressure of Railway Rigid Retaining Wall Considering Soil Arch Effect

    路维; 孙文君; 王学民; 杨鹏志; 崔立功


    对考虑土拱效应的水平微元滑裂体水平向及竖向静力平衡方程进行了分析,获得了平移模式下的刚性挡土墙侧向主动土压力、主动土压力合力及其作用点的计算公式,并与模型试验数据进行了比较.结果表明:本文得到的平移模式下刚性挡土墙墙后主动土压力分布与模型试验结果吻合较好,最大值比实测值略大;墙背主动土压力沿墙高呈非线性分布,墙背主动土压力合力作用点高度大于墙高的1/3.%This paper analyses the horizontal and vertical static equilibrium equations of horizontal differential sliding mass with soil arch. New formulas of rigid retaining wall lateral active earth pressure,active earth pressure resultant force and its action position were derived under translation mode. The Comparisons between the theoretical and measured values shown that the lateral active earth pressure distribution of rigid retaining wall under translation mode from the proposed formulas are agree well with results from the model test,and the maximum value from calculation is slightly larger than measured value. The distribution of the lateral active earth pressure is nonlinear along the wall height,and the action position of active earth pressure is larger than one third of the wall height.

  16. Wall Turbulence.

    Hanratty, Thomas J.


    This paper gives an account of research on the structure of turbulence close to a solid boundary. Included is a method to study the flow close to the wall of a pipe without interferring with it. (Author/JN)

  17. Seismic evaluation of existing reinforced concrete frame considering effect of infill walls%考虑填充墙影响的 RC 框架结构抗震性能评估

    郑文婷; 刘景良; 吴兆旗


    Quantified seismic performance levels of pure frame and frame with infill walls were pres-ented based on test data of existing frames at home and abroad.The proposed performance levels were employed to evaluate seismic performance of an existing frame by conducting time history analy-sis.The results show that the infill walls act as diagonal trusses to enhance the stiffness of the frames even if they are in elastic-plastic state.It is confirmed that seismic performance evaluation based on time history analysis provides more detailed information than seismic appraisal of buildings,and is a more accurate and feasible method.%分析国内外 RC 框架试验数据,提出不考虑填充墙影响和考虑填充墙影响的 RC 框架结构的量化性能水准。根据所提出的量化性能水准,采用时程分析方法对一栋 RC 框架结构的抗震性能进行评估。分析结果表明,填充墙在弹塑性阶段仍然能够充当支撑作用,提高框架结构的整体刚度;基于时程分析法的结构抗震性能评估方法是一种可行的全面反映结构抗震性能的详细评估方法,在一定程度上弥补了现行抗震鉴定标准经验性评判的不足。

  18. Reinforcement Learning: A Tutorial.


    The purpose of this tutorial is to provide an introduction to reinforcement learning (RL) at a level easily understood by students and researchers in...provides a simple example to develop intuition of the underlying dynamic programming mechanism. In Section (2) the parts of a reinforcement learning problem... reinforcement learning algorithms. These include TD(lambda) and both the residual and direct forms of value iteration, Q-learning, and advantage learning

  19. Mechanically reinforced glass beams

    Nielsen, Jens Henrik; Olesen, John Forbes


    to breakage without any warning or ductility, which can be catastrophic if no precautions are taken. One aspect of this issue is treated here by looking at the possibility of mechanically reinforcing glass beams in order to obtain ductile failure for such a structural component. A mechanically reinforced...... the mechanical behavior of the beam is explained. Finally, some design criterions for reinforced glass beams are discussed....

  20. Study on energy dissipation mechanism of reinforced concrete frame-shear wall structure under rare earthquakes%罕遇地震作用下钢筋混凝土框架-剪力墙结构的耗能机制分析

    缪志伟; 叶列平


    为了确定钢筋混凝土框架-剪力墙结构在强震作用下的合理耗能机制,对多个结构算例进行多条强震记录作用下的弹塑性时程分析.通过分析总累积耗能在各类构件中的分配和各类构件耗能沿结构高度方向的分布模式,研究结构的典型耗能机制类型,讨论耗能机制与结构参数的关系,并对不同的耗能机制进行评价.结果表明,“强墙肢弱连梁”整体型耗能机制使结构具有良好的抗震性能,应作为结构耗能机制设计的目标,“强连梁弱墙肢”耗能机制则应予以避免;连梁与墙肢的相对刚度关系是影响结构耗能机制的关键因素,框架和剪力墙相对数量的改变则不会明显影响结构耗能机制.对具有小跨高比连梁的结构,建议采用连梁水平分缝措施引导结构形成“强墙肢弱连梁”耗能机制,并通过算例分析验证了该措施的有效性.%In order to determine the reasonable structural energy dissipation mechanism under rare earthquakes, several reinforced concrete frame-shear wall structures were analyzed by elasto-plastic time-history analytical method under a series of strong earthquake records. Based on the energy distribution among different types of structural members and along the structural height, typical energy dissipation mechanisms were summarized and evaluated respectively. And also the influences of structural parameters on the energy dissipation mechanisms were discussed. The results show that that ' strong wall pier-weak coupling beam' mechanism, leading to good structural seismic performance, should be set as the objective of structural seismic design while the ' strong coupling beam-weak wall pier' mechanism should be avoided. It is also shown that energy dissipation mechanism is determined by the relative stiffness of coupling beam and wall pier in the shear wall rather than relative numbers of frame and shear wall in the whole structure. At last, the measure of

  1. Development and Properties of Glass Fiber Reinforced Plastics Geogrid

    WANG Qingbiao; ZHANG Cong; WEN Xiaokang; L Rongshan; LIANG Xunmei; LU Shide


    Glassfi ber reinforced plastics geogrid has a wide application in thefi eld of soil reinforcement because of its high strength, good toughness, and resistance to environmental stress, creep resistance and strong stability. In order to get high-powered glassfi ber reinforced plastics geogrid and its mechanical characteristics, the properties and physical mechanical index of geogrid have been got through the study of its raw material, production process and important quality index. The analysis and study have been made to the geogrid’s mechanical properties with loading speed, three-axial compression, temperature tensile test and FLAC3D numerical simulation, thus obtain the mechanical parameters of its displacement time curve, breaking strength and elongation at break. Some conclusions can be drawn as follows: (a) Using glassfi ber materials, knurling and coated projection process, the fracture strength and corrosion resistance of geogrid are greatly improved and the interlocking bite capability of soil is enhanced. (b) The fracture strength of geogrid is related to temperature and loading rate. When the surrounding rock pressure is fixed, the strength and anti-deformation ability of reinforced soil are significantly enhanced with increasing reinforced layers. (c) The pullout test shows the positive correlation between geogrid displacement and action time. (d) As a new reinforced material, the glass fi ber reinforced plastics geogrid is not mature enough in theoretical research and practical experience, so it has become an urgent problem both in theoretical study and practical innovation.

  2. Experimental analysis of passive earth pressure against rigid retaining wall under translation mode for finite soils%有限土体刚性挡墙平动模式被动土压力试验研究

    应宏伟; 张金红; 王小刚; 李冰河; 朱伟


    It is inappropriate to calculate the earth pressure for finite soils using the classical Coulomb or Rankine earth pressure theory. A series of laboratory model tests with different widths of backfill are conducted for the passive case of a rigid retaining wall subjected to horizontal translation. The change in lateral earth pressure distribution from the at-rest condition to the passive condition is monitored by using a set of pressure cells. The particle image velocimetry technique is employed to observe the development of a failure zone in the soils. The experiment results show that there is a good agreement between the measured earth pressures and the Coulomb’s solution in the case of infinite soils. However, the passive earth pressures on the moving retaining wall for finite soils are much more than the Coulomb’s solution. With the decrease of the soil width, the limited displacement of the wall under passive state seems to increase, and the passive earth pressures also increase significantly when the heights of the application points of the resultant earth pressure move down gradually. Moreover, with the decrease of the soil width, the heave of the backfill surface increases gradually, the inclination angles of the slip surface increase slightly, and the lateral earth pressures on the fixed boundary also increase gradually.%经典的库仑或朗肯土压力理论无法适用有限土体情况下的土压力问题。利用研制的土压力试验模型装置,进行了一组不同填土宽度的刚性挡墙平动模式室内模型试验,采用微型土压力盒量测从静止状态到被动极限状态的水平土压力分布的变化,利用颗粒图像测速技术研究土体内滑裂面发展规律。试验结果表明:半无限土体情况下的被动土压力大小、分布和合力作用点与库仑被动土压力较为接近。而有限宽度情况下移动挡墙上各深度的被动土压力值均大于库仑被动土压力,且土体宽度

  3. Wear Behaviour of Carbon Nanotubes Reinforced Nanocrystalline AA 4032 Composites

    Senthil Saravanari, M. S.; Kumaresh Babu, S. P.; Sivaprasad, K.


    The present paper emphasizes the friction and wear properties of Carbon Nanotubes reinforced AA 4032 nanocomposites prepared by powder metallurgy technique. CNTs are multi-wall in nature and prepared by electric arc discharge method. Multi-walled CNTs are blended with AA 4032 elemental powders and compaction followed by sintering to get bulk nanocomposites. The strength of the composites has been evaluated by microhardness and the surface contact between the nanocomposites and EN 32 steel has been evaluated by Pin on disk tester. The results are proven that reinforcement of CNTs play a major role in the enhancement of hardness and wear.

  4. Numerical Investigation Into The Behavior of Circular Pad Shallow Foundations Supported By Geogrid Reinforced Sand

    S. M. Marandi


    Full Text Available This study seeks to widen the pool of knowledge on the use and characteristics of geosynthetics, specifically in the area of circular foundations supported by geosynthetic reinforced sand. The main objective of the work was to increase the awareness of circular foundation systems and thus increase the accuracy of current laboratory methods. Also, compare the results with that of previous papers on the subject and to provide new model curves to estimate the bearing capacity of circular foundations. In this respect, the foundation and the soil underneath was modeled using four nots isoparameters finite element aid, while, for geogrid reinforcement, the four nots one-dimentional finite element model was used. The sand behavior was based on demolition elasto-plastic drucker-prager criteria and for the reinforcement the linear criteria was used. The paper investigates the effects of the reinforcement placing properties, soil properties, reinforcement properties, and the geometric properties of circular foundations. The results showed that; the bearing capacity ratio at a settlement level for geogrid reinforced sand is effected considerably by parameters such as: reinforcement placement, reinforcement layers, reinforcement strength, geometric properties of circular foundations, and effects of using granular soils. Based on the results achieved, a number of design curves have been developed to assist with the estimation (design of field bearing capacity of shallow foundations supported by geogrid reinforced soil. Keeping in mind the settlement limitations in real space, the curves have been developed for normal settlement levels up to a settlement ratio of 2.5%.

  5. Continuous Reinforced Concrete Beams

    Hoang, Cao Linh; Nielsen, Mogens Peter


    This report deals with stress and stiffness estimates of continuous reinforced concrete beams with different stiffnesses for negative and positive moments e.g. corresponding to different reinforcement areas in top and bottom. Such conditions are often met in practice.The moment distribution...

  6. Hierarchical Multiagent Reinforcement Learning


    In this paper, we investigate the use of hierarchical reinforcement learning (HRL) to speed up the acquisition of cooperative multiagent tasks. We...introduce a hierarchical multiagent reinforcement learning (RL) framework and propose a hierarchical multiagent RL algorithm called Cooperative HRL. In

  7. "Reinforcement" in behavior theory.

    Schoenfeld, W N


    In its Pavlovian context, "reinforcement" was actually a descriptive term for the functional relation between an unconditional and a conditional stimulus. When it was adopted into operant conditioning, "reinforcement" became the central concept and the key operation, but with new qualifications, new referents, and new expectations. Some behavior theorists believed that "reinforcers" comprise a special and limited class of stimuli or events, and they speculated about what the essential "nature of reinforcement" might be. It is now known that any stimulus can serve a reinforcing function, with due recognition of such parameters as subject species characteristics, stimulus intensity, sensory modality, and schedule of application. This paper comments on these developments from the standpoint of reflex behavior theory.

  8. Slope reinforcement design using geotextiles and geogrids

    Setser, Darrell M.


    A geotextile is defined by ASTM as: any permeable textile material used with foundation, soil, rock, earth, or any other geotechnical engineering related material, as a integral part of a man-made project, structure, or system. A geogrid is defined as: any geotextile-related material used in a similar manner to geotextiles. They are usually made of plastic, but can be metal or wood. Geotextiles and geogrids are collectively referred to as geosynthetics in this paper. Geosynthetic reinforcement of slopes is a relatively new option available to the civil engineer. Slope angles can be increased and 'poor' soil can be used to construct economical soil-geosynthetic facilities. Uncertainties exist in the complex interaction between the soil and the geosynthetic but there are numerous procedures which ignore this in the design. The design procedures available may be conservative yet still may be an economical alternative when compared to more conventional options.

  9. 工具式围堰在桥梁墩柱维修中的应用%Operation Method of the Tool-typed Recycling Double Wall Steel Cofferdam in Wate-pier Reinforcement Engineering in the Spring Tide of Poor Water

    刘昂; 吴中鑫; 朱慈祥


    In this paper,in the engineering background of detection and reinforcement project of the No.14~18 Pier of a bridge,the construction method of the Tool-Typed Double Wall Steel Cofferdam in the bridge of low clearance flyovers which is removable and recyclable in the spring tide of poor wa-ter is introduced.In the method,the factors,the spring tide of poor water,low clearance flyovers, and details of design and fabrication of the steel cofferdams are considered.An application example shows that the method can reduce construction time,cost,energy conservation and environmental protection..%以某桥梁15~18号桥墩检测加固项目为工程背景,介绍了某桥梁高潮差低净空下的工具式可拆卸循环利用双壁钢围堰使用方法,该工具式可拆卸循环利用双壁钢围堰的施工考虑了涨落潮变化、桥下净空较小等环境因素,以及围堰及辅助措施的设计、制作安装。应用证明,该方法具有减少施工工期、降低成本、节能环保等特点。

  10. Estudos laboratoriais do comportamento de um solo residual arenoso reforçado com fibras de polipropileno, visando à aplicação em estradas florestais Laboratory testing of a polypropylene fiber reinforced residual sandy soil for forest road application

    Tiago Pinto da Trindade


    Full Text Available Este trabalho teve como objetivo analisar o comportamento mecânico da mistura de um solo residual jovem de textura predominantemente arenosa reforçado com fibras de polipropileno, com vistas à aplicação em estradas florestais. Como ponto de partida, determinou-se, mediante os resultados de ensaios de compressão não-confinada, realizados em corpos-de-prova compactados na energia do ensaio Proctor Normal, que o quantitativo de 0,75% de fibras com 20 mm de comprimento foi a combinação responsável pelo maior ganho de resistência. Com a mistura solo-fibra composta por essa combinação, foram realizados ensaios triaxiais do tipo CID/Sat em corpos-de-prova compactados na energia anteriormente referida. Através desta pesquisa, foi possível avaliar: (i a influência da variação da umidade nos parâmetros de resistência mecânica do solo e das misturas solo-fibra e (ii a influência das fibras nos parâmetros de resistência ao cisalhamento do solo em estudo. Analisando os resultados, pôde-se concluir que o uso de fibras de polipropileno promoveu um ganho da ordem de 110% na resistência à compressão não-confinada e de 560% na coesão de intercepto do solo estudado.The purpose of this study was to analyze the mechanical behavior of a polypropylene fiber-reinforced young residual sandy soil for forest road application. The first step was to determine the best combination of fiber content and length that would give the greatest increase in unconfined compressive strength of mixture specimens compacted at the Standard Proctor effort. The best combination resulting from the laboratory test program was 0.75% fiber content and fiber 20-mm length. The next step in the testing program was to run triaxial CID/Sat tests in mixture specimens prepared with the best combination and compacted at the Standard Proctor effort. From the laboratory testing program data it was possible to evaluate the influence of the water content in the mechanical

  11. Research on the Penetration Behavior of Fe3 + in SB Slurry Wall%Fe 离子在 Soil - Bentonite Slurry wall中的渗透行为研究

    吕淑清; 刘锦伟


    采用实验室研究方法,研究了SB (Soil Bentonite )材料对Fe离子的吸附,以及Fe离子在SB Slurry wall 中的穿透行为,实验结果显示,SB 对 Fe 离子的吸附符合 langmuir 等温线,Fe 离子在 SB 中迁移时,导致 SB材料的渗透系数比纯水的渗透系数大一个数量级,Fe 离子流出浓度随着时间的增加在不断增加。%The method of laboratory research is adopted to study the adsorption of SB materials to Fe 3 + and the break-through behavior of Fe ions in SB Slurry wall .The results show that the adsorption SB material to Fe ion conforms to the Langmuir isotherm ;the migration of Fe3 + in SB causes the permeability coefficient increased to an order of magnitude and Fe3 + outflow concentration increases with the increase of time .

  12. The repair of ground cover of Bolivia-Brazil gas pipeline near Paraguay River crossing, in a swamp soft soil region, using geo synthetics reinforced backfilling; Reparo da cobertura do gasoduto Bolivia-Brasil junto ao Rio Paraguai, em trecho com solo mole, utilizando aterro reforcado com geosinteticos

    Costa, Cesar Augusto; Jorge, Kemal Vieira; Bechuate Filho, Pedro [TBG - Transportadora Brasileira Gasoduto Bolivia Brasil S.A., Campo Grande, MS (Brazil). Gerencia Regional Centro Oeste (CRGO); Teixeira, Sidnei H.C. [Geohydrotech Engenharia S.C. Ltda., Braganca Paulista, SP (Brazil)


    TBG - Transportadora Gasoduto Bolivia-Brasil S.A, executes routine maintenance works at the Gas Pipeline Right of Way, seeking its integrity. In the wetlands of Pantanal, near the Paraguay river crossing, the organic-alluvial soil was submitted to the process of subsidence. This process, associated with the river water flow erosion, shrank the soil volume and diminished or extinguished the pipeline land cover. The pipeline was exposed to the environment, and submitted to tension stresses and the risk of low cycle fatigue during the floods. The cathodic protection system also had to be evaluated, specially in the drought. To mitigate the problem, the embankment technique was adopted using sandy soil, reinforced with polyester geo-webs and with woven polipropene geo-textiles. The solution also used geo-webs with soil-cement as protection elements against the degradation of the geo-textiles blankets. Some monitoring works are associated with those interventions: monitoring of cathodic protection; topographical verification of horizontal and vertical displacements of the pipeline; levels of land covering, and rainfalls and flood measurement. The base of the embankment was built with hydraulic transported soil, and at the end consistently supported the gas pipeline. (author)

  13. Wall Art

    McGinley, Connie Q.


    The author of this article, an art teacher at Monarch High School in Louisville, Colorado, describes how her experience teaching in a new school presented an exciting visual challenge for an art teacher--monotonous brick walls just waiting for decoration. This school experienced only minimal instances of graffiti, but as an art teacher, she did…

  14. An experimental study on the influence of composite materials used to reinforce masonry ring beams

    Sisti, Romina; Corradi, Marco; Borri, Antonio


    For historic masonry constructions the out-of-plane wall behavior is critical to seismic performance. Because the main cause of out-of-plane collapses is the wall-to-wall level of connection, the application of a reinforced concrete (RC) ring beam at the eaves level of historic masonry buildings is an effective method to prevent an out-of-plane mechanism of a wall panel. However this effective reinforcing method presents some drawbacks. In order to address this, this paper describes the probl...

  15. Static load test of Arquin-designed CMU wall.

    Jensen, Richard Pearson; Cherry, Jeffery L.


    The Arquin Corporation has developed a new method of constructing CMU (concrete masonry unit) walls. This new method uses polymer spacers connected to steel wires that serve as reinforcing as well as means of accurately placing the spacers so that the concrete block can be dry stacked. The hollows of the concrete block used in constructing the wall are then filled with grout. As part of a New Mexico Small Business Assistance Program (NMSBAP), Sandia National Laboratories conducted a series of tests that statically loaded wall segments to compare the Arquin method to a more traditional method of constructing CMU walls. A total of 12 tests were conducted, three with the Arquin method using a W5 reinforcing wire, three with the traditional method of construction using a number 3 rebar as reinforcing, three with the Arquin method using a W2 reinforcing wire, and three with the traditional construction method but without rebar. The results of the tests showed that the walls constructed with the Arquin method and with a W5 reinforcing wire withstood more load than any of the other three types of walls that were tested.

  16. Research on critical placement height of gravel column reinforced soft soil foundations%碎石桩处理软土地基临界填筑高度的研究

    陈继彬; 赵其华; 彭社琴


    目前计算碎石桩处理软土地基临界填筑高度的方法并不完善,没有考虑软基经碎石桩处理后复合地基强度的增加和地基排水固结能力的提高,基于此,依据固结理论,引入碎石桩复合地基固结计算的简化方法,修正按变形控制的临界填筑高度计算公式;并结合四川省遂-资高速公路软基变形监测数据,得出软基厚度在6.5~11.0 m范围内,观测所得的临界填筑高度为4.5~6.5 m,该观测值与修正公式计算值差异性不显著,证实所推导的解析式是切实可行的;在此基础上,初步探讨影响路堤临界填筑高度变化的因素,得出软基厚度、桩间距对其影响较为明显。%Calculation methods for the critical placement height of gravel column reinforced soft soil foundations are not perfect at present. The traditional calculation methods do not take the improvement of composite foundation's strength and the enhancement of foundation's drainage consolidation ability into account. Based on the consolidation theory, the simplified method of consolidation calculation of gravel column composite foundation is introduced, and it modifies the formula of the critical placement height according to the deformation control. Analyzing the settlement deformation observation data of the soft ground distributed along the Suining-Ziyang expressway in Sichuan province, results show that the thickness of clay in the study area is within 6.5-11 m and the observation value of critical placement height ranges from 4.5 to 6.5 m. The difference between observation values and calculation values with modified formula is±(0.1-0.4)m. It verifies that the formula deduced in this paper is applicable. Based on these, the factors influencing the critical placement height were discussed and it was found that the thickness of soft soil and the column spacing have more obvious influences on the critical placement height than other factors.

  17. Continuous Reinforced Concrete Beams

    Hoang, Cao Linh; Nielsen, Mogens Peter


    This report deals with stress and stiffness estimates of continuous reinforced concrete beams with different stiffnesses for negative and positive moments e.g. corresponding to different reinforcement areas in top and bottom. Such conditions are often met in practice.The moment distribution...... at the limit state of serviceability is in some simple cases determined by setting up the statical and the compatibility conditions.With these moment distributions, the maximum deflection and the reinforcement stresses at the span middle and at a support are calculated.The results are compared with results...

  18. Algorithms for Reinforcement Learning

    Szepesvari, Csaba


    Reinforcement learning is a learning paradigm concerned with learning to control a system so as to maximize a numerical performance measure that expresses a long-term objective. What distinguishes reinforcement learning from supervised learning is that only partial feedback is given to the learner about the learner's predictions. Further, the predictions may have long term effects through influencing the future state of the controlled system. Thus, time plays a special role. The goal in reinforcement learning is to develop efficient learning algorithms, as well as to understand the algorithms'

  19. Reinforcing the mineral layer

    Pishchulin, V.V.; Kuntsevich, V.I.; Seryy, A.M.; Shirokov, A.P.


    A way of reinforcing the mineral layer includes drilling holes and putting in anchors that are longer than the width of the layer strip being extracted. It also includes shortening the anchors as the strip is mined and reinforcing the remaining part of the anchor in the mouth of the hole. To increase the productivity and safety of the work, the anchors are shortened by cutting them as the strip is mined and are reinforced through wedging. The device for doing this has auxilliary lengthwise grooves in the shaft located along its length at an interval equal to the width of the band being extracted.

  20. Blast Design of Reinforced Concrete and Masonry Components Retrofitted with FRP


    ultimate flexural and shear resistance of the upgraded walls. The methodology for estimating the flexural resistance of concrete and masonry components...recommended value not including any environmental effects or debonding The FRP reinforcement is typically applied to a concrete or masonry wall...have enough tensile and shear strength to transfer the force and develop the strength of the bonded FRP reinforcement . The durability of the

  1. Experimental study on seismic behavior of raw-soil structure with rammed earth walls by different construction methods%不同夯筑方法的承重夯土墙体抗震性能试验

    卜永红; 王毅红; 李丽; 刘挺


    提出适用于生土结构房屋承重夯土墙体新的施工方法,对采用不同方法夯筑的承重夯土墙体的受力及抗震性能进行试验研究,设计了3个墙体试件,分别采用传统水平分层夯筑、错层夯筑和加销键夯筑。对试件施加竖向荷载和低周反复水平荷载,研究采用不同夯筑方法建造的夯土墙体在地震荷载作用下的破坏过程、破坏形态、滞回曲线和骨架曲线的特征,以及墙体的水平承载力和变形能力等;对比分析不同夯筑方法对夯土墙体水平受力性能和变形性能的影响。研究结果表明,与传统夯筑方法相比,错层夯筑法使墙体的承载和变形能力都得到提高;加销键夯筑使墙体的变形能力得到提高。%New construction methods were put forward to apply to rammed earth walls of raw-soil structure.Three specimens were built by the way of traditional horizontal layer,alternate layer and add-pin-key construction methods,the mechanical behavior and seismic behavior of which were studied.Vertical loading and low cycle reversed horizontal loading were carried out on specimens to study the failure process,failure mode,hysteretic curve and skeleton curve feature.The horizontal bearing capacity and deformation capacity of the walls also were studied,the influence of different construction methods on which was analyzed.Test results indicate that,compared with the traditional construction method,the horizontal bearing capacity and deformation capacity of the wall can be improved by alternate layer construction method,and the deformation capacity of the wall can be improved by add-pin-key construction method.

  2. Fiber-reinforced ceramics

    Belcheva, D. [Technological University `Prof. A. Zlatarov`, Bourgas (Bulgaria); Lubchev, L.; Jelezkov, G.; Georgiev, W.


    The possibilities for preparation of reinforced composite materials were studied. Test specimens based on different types of alumina matrices, plasticized with formaldehyde oligomer and polyvinyl alcohol, and reinforced with carbon and mullite fibers were prepared and investigated. The results confirmed that reinforced composite materials with valuable properties such as high thermal shock resistance, chemical resistance and mechanical strength can be produced. The density of technical alumina materials is lower, compared with that of pure alumina. The density can also be influenced by the type and quantity of the plasticizers used. By increasing the fiber content, the density of the material decreases. The shrinkage is influcenced by the type and the quantity of the reinforcing material. (orig.)



    The FIRE AND RESCUE Group of TIS Commission informs that the climbing wall in the yard of the Fire-fighters Station, is intended for the sole use of the members of that service, and recalls that access to this installation is forbidden for safety reasons to all persons not belonging to the Service.CERN accepts no liability for damage or injury suffered as a result of failure to comply with this interdiction.TIS/DI

  4. Reinforcement Lernen mit Regularisierungsnetzwerken

    Jung, Tobias


    Die Arbeit behandelt das Problem der Skalierbarkeit von Reinforcement Lernen auf hochdimensionale und komplexe Aufgabenstellungen. Unter Reinforcement Lernen versteht man dabei eine auf approximativem Dynamischen Programmieren basierende Klasse von Lernverfahren, die speziell Anwendung in der Künstlichen Intelligenz findet und zur autonomen Steuerung simulierter Agenten oder realer Hardwareroboter in dynamischen und unwägbaren Umwelten genutzt werden kann. Dazu wird mittels Regression aus Sti...

  5. Reinforcement learning in scheduling

    Dietterich, Tom G.; Ok, Dokyeong; Zhang, Wei; Tadepalli, Prasad


    The goal of this research is to apply reinforcement learning methods to real-world problems like scheduling. In this preliminary paper, we show that learning to solve scheduling problems such as the Space Shuttle Payload Processing and the Automatic Guided Vehicle (AGV) scheduling can be usefully studied in the reinforcement learning framework. We discuss some of the special challenges posed by the scheduling domain to these methods and propose some possible solutions we plan to implement.

  6. Covert Reinforcement: A Partial Replication.

    Ripstra, Constance C.; And Others

    A partial replication of an investigation of the effect of covert reinforcement on a perceptual estimation task is described. The study was extended to include an extinction phase. There were five treatment groups: covert reinforcement, neutral scene reinforcement, noncontingent covert reinforcement, and two control groups. Each subject estimated…

  7. Multiwall carbon nanotubes reinforced epoxy nanocomposites

    Chen, Wei

    The emergence of carbon nanotubes (CNTs) has led to myriad possibilities for structural polymer composites with superior specific modulus, strength, and toughness. While the research activities in carbon nanotube reinforced polymer composites (NRPs) have made enormous progress towards fabricating next-generation advanced structural materials with added thermal, optical, and electrical advantages, questions concerning the filler dispersion, interface, and CNT alignment in these composites remain partially addressed. In this dissertation, the key technical challenges related to the synthesis, processing, and reinforcing mechanics governing the effective mechanical properties of NRPs were introduced and reviewed in the first two chapters. Subsequently, issues on the dispersion, interface control, hierarchical structure, and multi-functionality of NRPs were addressed based on functionalized multi-walled carbon nanotube reinforced DGEBA epoxy systems (NREs). In chapter 3, NREs with enhanced flexural properties were discussed in the context of improved dispersion and in-situ formation of covalent bonds at the interface. In chapter 4, NREs with controlled interface and tailored thermomechanical properties were demonstrated through the judicious choice of surface functionality and resin chemistry. In chapter 5, processing-condition-induced CNT organization in hierarchical epoxy nanocomposites was analyzed. In Chapter 6, possibilities were explored for multi-functional NREs for underwater acoustic structural applications. Finally, the findings of this dissertation were concluded and future research was proposed for ordered carbon nanotube array reinforced nanocomposites in the last chapter. Four journal publications resulted from this work are listed in Appendix.

  8. Wind Load Test of Earthbag Wall

    Ryan Scott


    Full Text Available Earthbag construction is a sustainable, low-cost, housing option for developing countries. Earthbag structures are built of individual soil-filled fabric bags (i.e., sand bags stacked in a running bond pattern. Once stacked, earthbags are compacted and the soil inside the bags is dried in-place to form earthen bricks. Barbed wires are placed between each course to affect shear transfer within the wall. Results of an out-of-plane load test on a full-scale earthbag wall are presented in this paper. The wall was subjected to out-of-plane pressure up to 3.16 kPa, which resulted in plastic deformations up to 50 mm. The wall did not collapse during loading. Wall behavior and force transfer mechanisms are discussed.




    Fighting cocks were conditioned to emit a key-pecking response on a fixed ratio reinforcement schedule leading to the visual image of another fighting cock. In addition, the relative reinforcing properties of the visual reinforcer were compared with food and water reinforcers in a three-choice, non-reversible option situation. The relative reinforcing effects of mirror presentation and another rooster visually presented through a window, were compared. The mirror maintained a relatively lower response output.

  10. Kinematic framework for evaluating seismic earth pressures on retaining walls

    Brandenberg, Scott J.; Mylonakis, George; Stewart, Jonathan P.


    © 2015 American Society of Civil Engineers.During earthquake ground shaking earth pressures on retaining structures can cyclically increase and decrease as a result of inertial forces applied to the walls and kinematic interactions between the stiff wall elements and surrounding soil. The application, based on limit equilibrium analysis, of a pseudostatic inertial force to a soil wedge behind the wall [the mechanism behind the widely-used Mononobe- Okabe (M-O) method] is a poor analogy for ei...

  11. Cellulose nanocrystals reinforced foamed nitrile rubber nanocomposites.

    Chen, Yukun; Zhang, Yuanbing; Xu, Chuanhui; Cao, Xiaodong


    Research on foamed nitrile rubber (NBR)/cellulose nanocrystals (CNs) nanocomposites is rarely found in the literatures. In this paper, CNs suspension and NBR latex was mixed to prepared the foamed NBR/CNs nanocomposites. We found that the CNs mainly located in the cell walls, effectively reinforcing the foamed NBR. The strong interaction between the CNs and NBR matrix restricted the mobility of NBR chains surrounding the CNs, hence increasing the crosslink density of the NBR matrix. CNs exhibited excellent reinforcement on the foamed NBR: a remarkable increase nearly 76% in the tensile strength of the foamed nanocomposites was achieved with a load of only 15 phr CNs. Enhanced mechanical properties make the foamed NBR/CNs nanocomposites a promising damping material for industrial applications with a potential to reduce the petroleum consumption.

  12. Analysis of Risk Management of Soil Nailing Wall for Expansive Red Clay Cut Slope%某膨胀性红土路堑边坡土钉墙风险管理实例分析

    丁兆锋; 魏永幸; 罗一农


    研究目的:铁路路基工程类风险管理技术处于刚起步阶段,可供借鉴的风险管理资料有限,在风险数据库的建设、风险因素的识别、预测模型的建立、风险因素动态变化的定量刻画,承灾体识别和易损性定量评价等方面存在诸多难题.本文针对上述难题以某膨胀土路堑边坡土钉墙工点为例,在阐述风险管理流程的基础上,详细介绍综合层次分析法、专家调查法、模糊评价法的科学风险管理方法体系及其具体操作步骤,以为铁路路基工程类风险管理技术方法研究提供借鉴和指导.研究结论:以层次分析法、专家调查法、模糊评价法相结合的风险管理体系,具有层次鲜明、步骤清晰,分析细致的特点,其分析结果与实际情况相符,是可靠的.自然与环境风险、施工风险以及设计风险对该段膨胀土土钉墙风险评价结果影响较大,因此在充分考虑自然与环境因素的前提下,合理的设计并严格按照设计施工,是降低该段膨胀性红土路堑边坡土钉墙工点坍塌风险的关键.%Research purposes:The risk management technology for the railway subgrade engineering is just in the beginning stage and there is a little reference information on it. There are many problems in the establishment of the risk database, the identification of the risk factors, the establishment of the prediction model, the quantitative characterization of the dynamic changes of the risk factors, the recognition of the hazard - affected body and the quantitative evaluation of the vulnerability. Aiming at the problems mentioned above, and taking an expansive soil nailing wall for the cut slope as an example, this paper expounds the risk management process and introduces the scientific risk management system composes of the analytic hierarchy process method, expert investigation method and fuzzy evaluation method and its operation steps for providing the reference and guidance to

  13. Application of FBG Sensing Technology in Stability Analysis of Geogrid-Reinforced Slope.

    Sun, Yijie; Xu, Hongzhong; Gu, Peng; Hu, Wenjie


    By installing FBG sensors on the geogrids, smart geogrids can both reinforce and monitor the stability for geogrid-reinforced slopes. In this paper, a geogrid-reinforced sand slope model test is conducted in the laboratory and fiber Bragg grating (FBG) sensing technology is used to measure the strain distribution of the geogrid. Based on the model test, the performance of the reinforced soil slope is simulated by finite element software Midas-GTS, and the stability of the reinforced soil slope is analyzed by strength reduction method. The relationship between the geogrid strain and the factor of safety is set up. The results indicate that the measured strain and calculated results agree very well. The geogrid strain measured by FBG sensor can be applied to evaluate the stability of geogrid-reinforced sand slopes.

  14. Application of FBG Sensing Technology in Stability Analysis of Geogrid-Reinforced Slope

    Sun, Yijie; Xu, Hongzhong; Gu, Peng; Hu, Wenjie


    By installing FBG sensors on the geogrids, smart geogrids can both reinforce and monitor the stability for geogrid-reinforced slopes. In this paper, a geogrid-reinforced sand slope model test is conducted in the laboratory and fiber Bragg grating (FBG) sensing technology is used to measure the strain distribution of the geogrid. Based on the model test, the performance of the reinforced soil slope is simulated by finite element software Midas-GTS, and the stability of the reinforced soil slope is analyzed by strength reduction method. The relationship between the geogrid strain and the factor of safety is set up. The results indicate that the measured strain and calculated results agree very well. The geogrid strain measured by FBG sensor can be applied to evaluate the stability of geogrid-reinforced sand slopes. PMID:28294995

  15. Behavior of reinforced concrete beams reinforced with GFRP bars

    D. H. Tavares

    Full Text Available The use of fiber reinforced polymer (FRP bars is one of the alternatives presented in recent studies to prevent the drawbacks related to the steel reinforcement in specific reinforced concrete members. In this work, six reinforced concrete beams were submitted to four point bending tests. One beam was reinforced with CA-50 steel bars and five with glass fiber reinforced polymer (GFRP bars. The tests were carried out in the Department of Structural Engineering in São Carlos Engineering School, São Paulo University. The objective of the test program was to compare strength, reinforcement deformation, displacement, and some anchorage aspects between the GFRP-reinforced concrete beams and the steel-reinforced concrete beam. The results show that, even though four GFRP-reinforced concrete beams were designed with the same internal tension force as that with steel reinforcement, their capacity was lower than that of the steel-reinforced beam. The results also show that similar flexural capacity can be achieved for the steel- and for the GFRP-reinforced concrete beams by controlling the stiffness (reinforcement modulus of elasticity multiplied by the bar cross-sectional area - EA and the tension force of the GFRP bars.

  16. Preference for 50% reinforcement over 75% reinforcement by pigeons.

    Gipson, Cassandra D; Alessandri, Jérôme J D; Miller, Holly C; Zentall, Thomas R


    When pigeons are given a choice between an initial-link alternative that results in either a terminal-link stimulus correlated with 100% reinforcement or a stimulus correlated with 0% reinforcement (overall 50% reinforcement) and another initial-link alternative that always results in a terminal-link stimulus correlated with 100% reinforcement, some pigeons show a preference for the initial-link alternative correlated with 50% reinforcement. Using this procedure, in Experiment 1, we found a relatively modest preference for 100% over 50% reinforcement. In Experiment 2, we decreased the reinforcement density for the second initial-link alternative to 75% and found a significant preference for the 50% reinforcement initial-link alternative. It may be that this "maladaptive" behavior results from a positive contrast between the expectation of reinforcement correlated with the 50% reinforcement initial-link alternative and the terminal-link stimulus correlated with 100% reinforcement. But apparently, the complementary negative contrast does not develop between the expectation of reinforcement correlated with the 50% reinforcement initial-link alternative and the terminal-link stimulus correlated with 0% reinforcement that often follow. Such paradoxical choice may account for certain human appetitive risk-taking behavior (e.g., gambling) as well.

  17. 土工布加筋土界面摩擦特性试验研究%Experimental research on interface frictional behaviors of the geotextile-reinforced soil

    杨敏; 李宁; 刘新星; 刘乃飞; 苏立海


    Based on the loess filled embankment in Yan'an new airport,and with the geotextile used in engineering practice as reinforcement material,the geotextile synthetic material testing machine jointly developed by Xi'an Yaxing Civil Engineering Instrument adopted to carry out the direct shear tests and pull tests of geotextiles-loess interface so that the direct shear and pull strengths and friction coefficients between geotentile soil interfaces in the case of differ-ent compactness are tested.The test results indicate:①The curves of shear displacement and shear stress is hardening type and the curves of drawing displacement and tensile stress is soften-ing type;②The interface strength of geotextiles-loess conforms with the Mohr-Coulomb strength theory.The friction behaviors of the geotextile-loess interface is very good.But the friction coef-ficient of direct shear is greater than that of pull test in the same condition;③In the shearing conditions,the interface strength of geotextiles-loess is not sensitive to the compaction degree, but in the drawing conditions,the compaction degree has a significant effect on interfacial cohe-sive force.%以延安新机场黄土高填方为依托,以工程实际使用的土工布作为筋材,采用与西安亚星土木仪器有限公司共同研制的土工合成材料试验机,进行了黄土加筋土的直剪试验和拉拔试验,测试了不同压实度条件下筋土界面间的直剪和拉拔强度以及摩擦系数.试验结果表明:①剪切位移与剪应力关系曲线为硬化型,而拉拔位移与拉应力关系曲线为软化型;②土工布与黄土的界面强度在直剪和拉拔条件下均符合莫尔库仑强度理论,土工布与黄土间具有较好的摩擦特性,但相同条件下直剪摩擦系数大于拉拔摩擦系数;③剪切条件下筋土界面强度参数对压实度不敏感,而拉拔条件下压实度对界面粘聚力影响显著.

  18. Active Earth Pressure for Non﹣vertical Rigid Retaining Wall Considering Soil Arching Effect%考虑土拱效应的非垂直刚性挡墙主动土压力

    孙文君; 宋杨; 王学民; 王蓉蓉; 杨鹏志


    为研究非垂直刚性挡墙的主动土压力计算方法,根据土拱效应原理、微分水平层法以及水平向静力平衡条件,得到了平移模式下非垂直刚性挡土墙墙后填土破裂角的计算式,并进一步根据力与力矩平衡条件获得了平移模式下非垂直刚性挡土墙墙后主动土压力、合力及其作用点等的计算式。通过计算对各种特殊情况下的破裂角和主动土压力进行分析,讨论了墙背倾角、墙土摩擦角等对破裂角、法向主动土压力系数、法向主动土压力和主动土压力合力作用点高度等的影响。该研究可为非垂直墙背的支挡结构设计中的主动土压力计算提供更为合理的理论支持。%Active earth pressure for non﹣vertical rigid retaining wall is studied. Considering soil arching effect,according to differential level layer method and horizontal static equilibrium,a new formula of the inclinations of sliding surface behind the inclined rigid retaining wall is obtained under translation mode. Then according to static and moment equilibrium,a new expression of the active earth pressure were derived,and those of the active earth force and the height of application of its is also putted for﹣ward. The special solutions of the failure angle and the active normal earth pressure are discussed under various boundary conditions. In addition,the effects of the inclination of wall﹣back surface,the internal friction angle of backfill and the wall﹣soil friction angle on the failure angle,the active normal earth pres﹣sure and its coefficient,and application height the active earth force is investigated. This study can provide a more reasonable theoretical support for the design calculation of the active earth pressure against the non﹣vertical rigid retaining structures.

  19. Geotehnical Properties of Plastic Stabilized Lateritic Soil

    Akinola Johnson Olarewaju


    Stabilization is the combination of soils and additives to change its properties and remain in its stable compacted state without undergoing any change under effect of exposure to weather and traffic. Soil stabilization through the reinforced soil construction is an efficient and reliable technique for improving the strength and stability of soils. The lateritic soil used in this study was taken along Papa-Ilaro road Ajegunle at Abalabi, Ogun State, Nigeria and the solid plastic wastes were t...

  20. Shear wall ultimate drift limits

    Duffey, T.A. [Duffy, (T.A.) Tijeras, NM (United States); Goldman, A. [Goldman, (A.), Sandia, Los Alamos, NM (United States); Farrar, C.R. [Los Alamos National Lab., NM (United States)


    Drift limits for reinforced-concrete shear walls are investigated by reviewing the open literature for appropriate experimental data. Drift values at ultimate are determined for walls with aspect ratios ranging up to a maximum of 3.53 and undergoing different types of lateral loading (cyclic static, monotonic static, and dynamic). Based on the geometry of actual nuclear power plant structures exclusive of containments and concerns regarding their response during seismic (i.e.,cyclic) loading, data are obtained from pertinent references for which the wall aspect ratio is less than or equal to approximately 1, and for which testing is cyclic in nature (typically displacement controlled). In particular, lateral deflections at ultimate load, and at points in the softening region beyond ultimate for which the load has dropped to 90, 80, 70, 60, and 50 percent of its ultimate value, are obtained and converted to drift information. The statistical nature of the data is also investigated. These data are shown to be lognormally distributed, and an analysis of variance is performed. The use of statistics to estimate Probability of Failure for a shear wall structure is illustrated.

  1. Modelling reinforcement corrosion in concrete

    Michel, Alexander; Geiker, Mette Rica; Stang, Henrik


    A physio-chemical model for the simulation of reinforcement corrosion in concrete struc-tures was developed. The model allows for simulation of initiation and subsequent propaga-tion of reinforcement corrosion. Corrosion is assumed to be initiated once a defined critical chloride threshold...... is reached causing the formation of anodic and cathodic regions along the reinforcement. Critical chloride thresholds, randomly distributed along the reinforcement sur-face, link the initiation and propagation phase of reinforcement corrosion. To demonstrate the potential use of the developed model......, a numerical example is pre-sented, that illustrates the formation of corrosion cells as well as propagation of corrosion in a reinforced concrete structure....

  2. Advancements in subsurface barrier wall technology

    Mutch, R.D. Jr.; Ash, R.E. IV; Caputi, J.R. [Eckenfelder Inc., Mahwah, NJ (United States)


    Subsurface barrier walls have been an important component of site remediation efforts for nearly thirty years. However, until the last decade, limited design options were available for barrier wall construction. Most barrier walls were constructed using traditional technologies such as soil-bentonite slurry trench and, in some instances, conventional compacted clay. While other technologies certainly existed, such as vibrating beam and sheet pile walls, they represented a minor share of the remediation market. Today the remediation engineer considering a subsurface barrier wall-based remediation is confronted with a baffling array, of new technologies and permutations of these technologies. Moreover, new technologies are entering the marketplace seemingly on a monthly basis. A partial listing of available barrier wall technologies is presented.

  3. 大坝砾石土防渗心墙填筑质量快速检测方法研究%Research on Rapid Detection Method for Filling Quality of Impervious Core Wall with Gravelly Soil in Dam

    保华富; 王海波; 庞桂; 王坤


    针对长河坝水电站砾石土心墙填筑压实质量需要,用全料压实度和细料压实度进行双控的质量快速检测控制,通过系列比较试验和分析,提出了一种砾石土填筑压实质量控制的快速检测方法。与常规标准检测方法所得结果相比,各项检测指标偏差完全在试验规程允许误差范围内。本方法简捷、快速、经济实用,可大幅缩短检测时间以满足高强度大方量填筑质量检测控制要求,大坝初期填筑应用结果表明本方法是一种砾石土填筑质量控制快速有效的检测方法。%According to the compaction quality of the gravelly soil filling for the core wall of Changheba Hydropower Sta-tion as well as the quality detection and control with full material compaction degree and fine material compaction degree , a rapid detection method for the compaction quality control of gravelly soil filling is proposed based on a series of compar-ative experiments and analysis .Compared with the results from conventional standard detection methods ,the deviation of each detection indexes of this method is within the scope of permissible error in the test procedure .The proposed method is simple ,rapid ,economic and practical ,with which the detection time can be greatly shortened so as to meet the quality detection and control requirements for high strength and large volume filling .The application results for early dam filling show that this method is a kind of fast and efficient detection method for the quality control of gravelly soil filling .


    黄炜; 薛伟伟; 张程华; 李云璋


    Capacity spectrum method was adopted to perform nonlinear static seismic response(pushover) analysis for eco-composite wall structure with grouped pile foundation resting on natural foundation soil.The substructure technique was adopted to simulate pile group with a group of springs,the grouped pile stiffness was determined with Davies method.According to the rigid frame-equivalent brace model,the Pushover model of soil-pile-structure interaction system was established.The differences of the results of two models under different earthquake intensities were discussed.The culated results show that in frequent earthquake conditions,structure performance point vertex displacement Un(rigid foundation) U′ n(interaction);while in rare earthquake conditions,There is the Un(rigid foundation) U′ n(interaction).When considering soil pile structure interaction,under the same seismic intensity conditions the base shear at performance point of the is increased as compared with a rigid foundation.%基于能力谱方法应用子结构原理对天然地基上带群桩基础的生态复合墙结构进行平面的静力弹塑性(Pushover)分析。建立弹簧单元模拟群桩基础,采用Davies方法确定桩的刚度;基于刚架-等效斜撑力学模型,提出考虑土-桩-生态复合墙结构共同作用的整体分析模型,并对比分析在不同地震烈度作用时土-桩-结构的共同工作问题。计算结果表明:在多遇地震条件下,结构性能点处的顶点位移Un(刚性地基)小于Un'(相互作用),而在罕遇地震条件下,则有Un(刚性地基)大于Un'(相互作用);考虑土-桩-结构相互作用后,相同地震烈度条件下结构在性能点时的基底剪力较刚性地基情形有所增大。

  5. 榆林卫城南城墙夯土改性加固试验研究%Experiment Research of Reinforcement by Rammed Soil of Yulin Acropolis South City Wall

    陈平; 杨瑜瑞; 郝宏伟; 宋泽维






    Full Text Available En este artículo se compara el comportamiento de cuatro muros aislados de concreto reforzado (CR con aberturas: dos muros prototipo ensayados bajo carga cuasi-estática cíclica (CEC y dos muros ensayados bajo excitación de mesa vibratoria. Las variables estudiadas fueron la cuantía de acero en el alma, el tipo de acero de refuerzo en el alma y el método de ensaye. A partir de la respuesta medida se verificó que la historia de carga de los ensayos CEC ignora los efectos dinámicos fundamentales observados en estructuras sometidas a cargas sísmicas. Cuando las respuestas dinámicas y CEC cíclicas se compararon, se observó que las propiedades de degradación de rigidez y resistencia dependen de la velocidad de aplicación de carga, los mecanismos de resistencia asociados a los modos de falla, el número de ciclos y los parámetros acumulados de la demanda de ductilidad y energía disipada. Por lo tanto, los datos obtenidos a partir de ensayos CEC no siempre se pueden suponer de forma segura como un límite inferior de la capacidad esperada. En el artículo también se proponen modelos de degradación de rigidez y resistencia para muros de CR con aberturas sometidos a carga del tipo sísmica.

  7. Bearing Capacity of High Density Polyethylene (HDPE Reinforced Sand Using Plate Load Test

    Er. Aly K


    Full Text Available The work presented here is a study to examine the improvement in bearing capacity of coastal sand of Trivandrum, Kerala, India using high density polyethylene (HDPE /woven fabric as reinforcement in discrete layers. The bearing capacity was evaluated using plate load test. The effect of reinforcement configurations like sheet reinforcement (sanded with adhesive, with adhesive and sheet alone and strip reinforcement (single and grid pattern are investigated. The test parameters chosen for the present study are, depth of topmost layer of reinforcement layer below footing, compacted density and number of layers of reinforcement etc. From the tests, it has been observed that sheet reinforcement is more effective than sheet sanded with adhesive and strip reinforcements. It is found that the synthetic adhesive gives no binding action at the interface of the reinforcement and soil. But it is to be noted that the sheet with adhesive dried has a marked influence on the bearing capacity especially at lower densities. The strip reinforcements in single pattern is considered to be a favorable choice for minimum reinforcement. The strip reinforcement in single or grid pattern gives sufficient improvement in strength.

  8. Composite panel, wall assembly and components therefor

    Kruger, P.J.


    This invention is concerned with improvements in wall assemblies made of a plurality of composite wall panels, such as concrete wall panels, and components and connectors for such assemblies. The invention is also concerned with a method of making such composite wall panels by molding concrete to form a concrete panel. It is particularly applicable for the provision of upstanding walls around oil tanks and hydrocarbon storage facilities, thereby to form part of a containment structure that can satisfy safety regulations for spills around such facilities. In accordance with another aspect of the invention, there is provided a composite building product comprising a concrete panel, said panel being obtained by molding a respective concrete composition. The panel has at least one metal hinge element integrally secured at a respective peripheral edge, with said metal hinge element being secured at the panel to project sufficiently therefrom so as to present a first hinge element. Several of the panels can be connected in a corral-type wall assembly in a variety of configuration. Another aspect of the invention provides, for use in a wall assembly, a portable composite panel comprising a concrete panel body, which is obtained by molding a respective concrete composition; and a frame assembly for reinforcing the peripheral edges of said concrete panel body. The frame assembly includes at least one metal member for provision of a first hing element for connecting a plurality of said panels in a corral-type wall assembly. 7 figs.

  9. Static inelastic analysis of RC shear walls

    Chen, Qin; Qian, Jiaru


    A macro-model of a reinforced concrete (RC) shear wall is developed for static inelastic analysis. The model is composed of RC column elements and RC membrane elements. The column elements are used to model the boundary zone and the membrane elements are used to model the wall panel. Various types of constitutive relationships of concrete could be adopted for the two kinds of elements. To perform analysis, the wall is divided into layers along its height. Two adjacent layers are connected with a rigid beam. There are only three unknown displacement components for each layer. A method called single degree of freedom compensation is adopted to solve the peak value of the capacity curve. The post-peak stage analysis is performed using a forced iteration approach. The macro-model developed in the study and the complete process analysis methodology are verified by the experimental and static inelastic analytical results of four RC shear wall specimens.

  10. Static inelastic analysis of RC shear walls

    陈勤; 钱稼茹


    A macro-model of a reinforced concrete (RC) shear wall is developed for static inelastic analysis. The model iscomposed of RC column elements and RC membrane elements. The column elements are used to model the boundary zone andthe membrane elements are used to model the wall panel. Various types of constitutive relationships of concrete could beadopted for the two kinds of elements. To perform analysis, the wall is divided into layers along its height. Two adjacent layersare connected with a rigid beam. There are only three unknown displacement components for each layer. A method called singledegree of freedom compensation is adopted to solve the peak value of the capacity curve. The post-peak stage analysis isperformed using a forced iteration approach. The macro-model developed in the study and the complete process analysismethodology are verified by the experimental and static inelastic analytical results of four RC shear wall specimens.

  11. Reinforcement Magnitude: An Evaluation of Preference and Reinforcer Efficacy

    Trosclair-Lasserre, Nicole M.; Lerman, Dorothea C; Call, Nathan A; Addison, Laura R; Kodak, Tiffany


    Consideration of reinforcer magnitude may be important for maximizing the efficacy of treatment for problem behavior. Nonetheless, relatively little is known about children's preferences for different magnitudes of social reinforcement or the extent to which preference is related to differences in reinforcer efficacy. The purpose of the current study was to evaluate the relations among reinforcer magnitude, preference, and efficacy by drawing on the procedures and results of basic experimenta...

  12. Reinforcement Magnitude: An Evaluation of Preference and Reinforcer Efficacy

    Trosclair-Lasserre, Nicole M.; Lerman, Dorothea C.; Call, Nathan A.; Addison, Laura R.; Kodak, Tiffany


    Consideration of reinforcer magnitude may be important for maximizing the efficacy of treatment for problem behavior. Nonetheless, relatively little is known about children's preferences for different magnitudes of social reinforcement or the extent to which preference is related to differences in reinforcer efficacy. The purpose of the current…

  13. 什邡市某已建住宅楼工程墙体裂缝控制%Crack Control for Walls in an Existing Residential Building in Shifang



    什邡市某6层砖混结构住宅楼,主体完工4个月后底层局部墙体出现裂缝。经分析,该建筑局部地基为软土,其含水量大、渗透性差,原设计采用的振冲法处理效果差,从而导致局部地基承载力不足、地基沉降量大且不均匀。针对墙体裂缝原因,采用灰土桩加固软土地基,同时采用钢筋混凝土梁加固基础,加固效果良好。%Cracks were emerged from partial ground-floor walls of a six-floor residential building with a masonry-concrete structure in Shifang, 4 months after the main body had completed. According to analysis, it was soft soil in the local foundation of this building, with large water content and poor permeability, the vibroflotation reinforcement effect was poor from the original design, resulted in insufficient carrying capacity of local foundation, and large and uneven of the foundation settlement amount . Based on these reasons, favourable effects of foundation stabilization are arisen from consolidated soft soil with lime-soil piles and reinforced foundation by applying reinforced concrete beams.

  14. Analysis on heat storage layer and thickness of soil wall in solar greenhouse based on theory of temperature-wave transfer%基于温波传递理论的日光温室土墙体蓄热层及墙体厚度分析

    白青; 张亚红; 孙利鑫


    The wall plays an important role in the study of the greenhouse. Heat storage layer and thickness of the wall are 2 key factors for studying wall thermal environment and optimizing the structure. As widely used wall in solar greenhouse, soil wall is typical and representative, and it is significant to study heat storage layer and thickness of soil wall. To study the varying rule of the heat storage layer and to find the optimum thickness of the wall, an experiment was performed in Yanghe County, Yinchuan, Ningxia, China in 2011. The fifth generation greenhouse with soil wall from Shouguang City, Shandong Province was used. The CR10X-2M and CR3000 data collectors from America were adopted, and 18 T-types thermocouple temperature probes were also used to test inner wall temperature at the positions of 0, 10, 20, 30, 40, 50, 60, 80, 100, 150, 200, 230, 250, 280 and 330 cm thickness (along horizontal direction of wall body). The temperature variation was analyzed in the horizontal direction. Indoor temperature and wall temperature were used to determine the thickness of heat storage layer. Besides, a method for calculating wall thickness was pointed out, which was based on wall temperature spreading speed. The results showed with the increase of wall depth, the variation of bilateral temperature-wave of the wall became less obvious. However, the temperatures were gradually decreased from wall surface to exterior surface. Temperature-wave amplitude approached zero at 50-230 cm depth of the wall surface, which was in a stable state. The thickness of heat storage layer was got by using the lowest temperature of inner greenhouse and inner wall. The temperature changed obviously in 0-50 cm and 280-330 cm depth of the wall, which showed wave layer, stable layer and insulation layer existing in the north wall of solar greenhouse, and the thickness of heat storage layer was various. In January, the amplitude of temperature within a month at wave layer ranged from 10.01 to 0

  15. Reinforcement and learning

    Servedio, M.R.; Sæther, S.A.; Sætre, G.-P.


    Evidence has been accumulating to support the process of reinforcement as a potential mechanism in speciation. In many species, mate choice decisions are influenced by cultural factors, including learned mating preferences (sexual imprinting) or learned mate attraction signals (e.g., bird song). It

  16. Motivated Reinforcement Learning

    Maher, Mary Lou


    Motivated learning is a research field in artificial intelligence and cognitive modelling. This book describes how motivated reinforcement learning agents can be used in computer games for the design of non-player characters that can adapt their behaviour in response to unexpected changes in their environment

  17. Glass Fibre Reinforced Polymers

    Nikolaou, N.; Karagianni, L.; Sarakiniatti, M.V.


    This "designers' manual" is made during the TIDO-course AR0533 Innovation & Sustainability. Fibre reinforced polymers (FRPs) have been used in many applications over the years, from new construction to retrofitting. They are lightweight, no-corrosive, exhibit high specific strength and specific

  18. Oscillations following periodic reinforcement.

    Monteiro, Tiago; Machado, Armando


    Three experiments examined behavior in extinction following periodic reinforcement. During the first phase of Experiment 1, four groups of pigeons were exposed to fixed interval (FI 16s or FI 48s) or variable interval (VI 16s or VI 48s) reinforcement schedules. Next, during the second phase, each session started with reinforcement trials and ended with an extinction segment. Experiment 2 was similar except that the extinction segment was considerably longer. Experiment 3 replaced the FI schedules with a peak procedure, with FI trials interspersed with non-food peak interval (PI) trials that were four times longer. One group of pigeons was exposed to FI 20s PI 80s trials, and another to FI 40s PI 160s trials. Results showed that, during the extinction segment, most pigeons trained with FI schedules, but not with VI schedules, displayed pause-peck oscillations with a period close to, but slightly greater than the FI parameter. These oscillations did not start immediately after the onset of extinction. Comparing the oscillations from Experiments 1 and 2 suggested that the alternation of reconditioning and re-extinction increases the reliability and earlier onset of the oscillations. In Experiment 3 the pigeons exhibited well-defined pause-peck cycles since the onset of extinction. These cycles had periods close to twice the value of the FI and lasted for long intervals of time. We discuss some hypotheses concerning the processes underlying behavioral oscillations following periodic reinforcement.

  19. Fibre reinforced polymer nanocomposites

    Vlasveld, D.P.N.


    In this thesis the results are described of the research on a combination of two types of composites: thermoplastic nanocomposites and continuous fibre composites. In this three-phase composite the main reinforcing phase are continuous glass or carbon fibres, and the matrix consists of a polyamide 6

  20. Turbomachine blade reinforcement

    Garcia Crespo, Andres Jose


    Embodiments of the present disclosure include a system having a turbomachine blade segment including a blade and a mounting segment coupled to the blade, wherein the mounting segment has a plurality of reinforcement pins laterally extending at least partially through a neck of the mounting segment.

  1. Glass Fibre Reinforced Polymers

    Nikolaou, N.; Karagianni, L.; Sarakiniatti, M.V.


    This "designers' manual" is made during the TIDO-course AR0533 Innovation & Sustainability. Fibre reinforced polymers (FRPs) have been used in many applications over the years, from new construction to retrofitting. They are lightweight, no-corrosive, exhibit high specific strength and specific sti

  2. Reinforcement and learning

    Servedio, M.R.; Sæther, S.A.; Sætre, G.-P.


    Evidence has been accumulating to support the process of reinforcement as a potential mechanism in speciation. In many species, mate choice decisions are influenced by cultural factors, including learned mating preferences (sexual imprinting) or learned mate attraction signals (e.g., bird song). It

  3. Reinforced aerodynamic profile


    The present invention relates to the prevention of deformations in an aerodynamic profile caused by lack of resistance to the bending moment forces that are created when such a profile is loaded in operation. More specifically, the invention relates to a reinforcing element inside an aerodynamic...

  4. Elastomer Reinforced with Carbon Nanotubes

    Hudson, Jared L.; Krishnamoorti, Ramanan


    Elastomers are reinforced with functionalized, single-walled carbon nanotubes (SWNTs) giving them high-breaking strain levels and low densities. Cross-linked elastomers are prepared using amine-terminated, poly(dimethylsiloxane) (PDMS), with an average molecular weight of 5,000 daltons, and a functionalized SWNT. Cross-link densities, estimated on the basis of swelling data in toluene (a dispersing solvent) indicated that the polymer underwent cross-linking at the ends of the chains. This thermally initiated cross-linking was found to occur only in the presence of the aryl alcohol functionalized SWNTs. The cross-link could have been via a hydrogen-bonding mechanism between the amine and the free hydroxyl group, or via attack of the amine on the ester linage to form an amide. Tensile properties examined at room temperature indicate a three-fold increase in the tensile modulus of the elastomer, with rupture and failure of the elastomer occurring at a strain of 6.5.

  5. Response deprivation, reinforcement, and economics

    Allison, James


    Reinforcement of an instrumental response results not from a special kind of response consequence known as a reinforcer, but from a special kind of schedule known as a response-deprivation schedule. Under the requirements of a response-deprivation schedule, the baseline rate of the instrumental response permits less than the baseline rate of the contingent response. Because reinforcement occurs only if the schedule deprives the organism of the contingent response, reinforcement cannot result ...

  6. Cellular fiber–reinforced concrete

    Isachenko S.; Kodzoev M.


    Methods disperse reinforcement of concrete matrix using polypropylene, glass, basalt and metal fibers allows to make the construction of complex configuration, solve the problem of frost products. Dispersed reinforcement reduces the overall weight of the structures. The fiber replaces the secondary reinforcement, reducing the volume of use of structural steel reinforcement. Cellular Fiber concretes are characterized by high-performance properties, especially increased bending strength and...

  7. Reinforcing aspects of androgens.

    Wood, Ruth I


    Are androgens reinforcing? Androgenic-anabolic steroids (AAS) are drugs of abuse. They are taken in large quantities by athletes and others to increase performance, often with negative long-term health consequences. As a result, in 1991, testosterone was declared a controlled substance. Recently, Brower [K.J. Brower, Anabolic steroid abuse and dependence. Curr. Psychiatry Rep. 4 (2002) 377-387.] proposed a two-stage model of AAS dependence. Users initiate steroid use for their anabolic effects on muscle growth. With continued exposure, dependence on the psychoactive effects of AAS develops. However, it is difficult in humans to separate direct psychoactive effects of AAS from the user's psychological dependence on the anabolic effects of AAS. Thus, studies in laboratory animals are useful to explore androgen reinforcement. Testosterone induces a conditioned place preference in rats and mice, and is voluntarily consumed through oral, intravenous, and intracerebroventricular self-administration in hamsters. Active, gonad-intact male and female hamsters will deliver 1 microg/microl testosterone into the lateral ventricles. Indeed, some individuals self-administer testosterone intracerebroventricularly to the point of death. Male rats develop a conditioned place preference to testosterone injections into the nucleus accumbens, an effect blocked by dopamine receptor antagonists. These data suggest that androgen reinforcement is mediated by the brain. Moreover, testosterone appears to act through the mesolimbic dopamine system, a common substrate for drugs of abuse. Nonetheless, androgen reinforcement is not comparable to that of cocaine or heroin. Instead, testosterone resembles other mild reinforcers, such as caffeine, nicotine, or benzodiazepines. The potential for androgen addiction remains to be determined.

  8. Classroom Management and Negative Reinforcement.

    Tauber, Robert T.

    Of the four simple consequences for behavior, none is more misunderstood than negative reinforcement. A Negative Reinforcement Quiz administered to 233 student teachers from two universities revealed that the vast majority of respondents mistakenly viewed negative reinforcement as a synonym for punishment, and believe that negative reinforcement…

  9. Short fiber reinforced thermoplastic blends

    Malchev, P.G.


    The present thesis investigates the potential of short fiber reinforced thermoplastic blends, a combination of an immiscible polymer blend and a short fiber reinforced composite, to integrate the easy processing solutions available for short fiber reinforced composites with the high mechanical perfo

  10. Short fiber reinforced thermoplastic blends

    Malchev, P.G.


    The present thesis investigates the potential of short fiber reinforced thermoplastic blends, a combination of an immiscible polymer blend and a short fiber reinforced composite, to integrate the easy processing solutions available for short fiber reinforced composites with the high mechanical perfo

  11. Falling walls

    It was 20 years ago this week that the Berlin wall was opened for the first time since its construction began in 1961. Although the signs of a thaw had been in the air for some time, few predicted the speed of the change that would ensue. As members of the scientific community, we can take a moment to reflect on the role our field played in bringing East and West together. CERN’s collaboration with the East, primarily through links with the Joint Institute for Nuclear Research, JINR, in Dubna, Russia, is well documented. Less well known, however, is the role CERN played in bringing the scientists of East and West Germany together. As the Iron curtain was going up, particle physicists on both sides were already creating the conditions that would allow it to be torn down. Cold war historian Thomas Stange tells the story in his 2002 CERN Courier article. It was my privilege to be in Berlin on Monday, the anniversary of the wall’s opening, to take part in a conference entitled &lsquo...

  12. Carbon nanotube reinforced metal binder for diamond cutting tools

    Sidorenko, Daria; Mishnaevsky, Leon; Levashov, Evgeny


    of grain size of the structural constituents of the binder, what in turn leads to the improved simultaneously hardness, Young modulus, plastic extension, bending strength and performances of the metallic binders. Comparing service properties of diamond end-cutting drill bits with and without MWCNT one......The potential of carbon nanotube reinforcement of metallic binders for the improvement of quality and efficiency of diamond cutting wheels is studied. The effect of multi-walled carbon nanotube (MWCNT) reinforcement on the mechanical properties i.e. hardness, Young modulus, strength and deformation...

  13. Nano-Aramid Fiber Reinforced Polyurethane Foam

    Semmes, Edmund B.; Frances, Arnold


    Closed cell polyurethane and, particularly, polyisocyanurate foams are a large family of flexible and rigid products the result of a reactive two part process wherein a urethane based polyol is combined with a foaming or "blowing" agent to create a cellular solid at room temperature. The ratio of reactive components, the constituency of the base materials, temperature, humidity, molding, pouring, spraying and many other processing techniques vary greatly. However, there is no known process for incorporating reinforcing fibers small enough to be integrally dispersed within the cell walls resulting in superior final products. The key differentiating aspect from the current state of art resides in the many processing technologies to be fully developed from the novel concept of milled nano pulp aramid fibers and their enabling entanglement capability fully enclosed within the cell walls of these closed cell urethane foams. The authors present the results of research and development of reinforced foam processing, equipment development, strength characteristics and the evolution of its many applications.

  14. 3-dimension FEM analysis of effect on soil slopes reinforced by anti-slide piles and reasonable pile locations%抗滑桩加固土坡效果及合理桩位的三维有限元分析

    邹盛堂; 戴自航


    Based on the software of ABAQUS, combined with the strength reduction method in elasto-plastic FEM, 3 - dimension numerical analyses on the soil slopes reinforced by anti - slide piles was conducted. Considered the pile - soil interaction, the limitations of slope collapse criterion in numerical non-convergence and characteristic position displacement inflexion with the strength reduction were discussed. Slope collapse criterion of characteristic position displacement inflexion combined with horizontal displacement limitation was provided for slopes reinforced by anti - slide piles. The variation laws of the critical slip surfaces and safety factors of slopes with changed pile locations were discussed. The reasonable locations of anti - slide piles were obtained by numerical simulation method.%基于ABAQUS有限元软件,采用弹塑性有限元强度折减法对抗滑桩加固的土坡进行三维数值分析.考虑桩-土相互作用,探讨强度折减法中以迭代不收敛和特征点位移拐点作为边坡失稳判据的局限性.对于抗滑桩加固的边坡,提出采用特征点位移拐点并结合水平位移限值作为边坡临界破坏的评价标准,分析边坡潜在最危险滑动面和安全系数随抗滑桩桩位变化的规律,从数值模拟角度探讨边坡加固中桩位的合理设置位置.

  15. Impacts of Soil Moisture Content and Vegetation on Shear Strength of Unsaturated Soil

    YANG Yong-hong; ZHANG Jian-guo; ZHANG Jian-hui; LIU Shu-zhen; WANG Cheng-hua; XIAO Qing-hua


    It is analyzed that the impacts of vegetation type and soil moisture content on shear strength of unsaturated soil through direct shearing tests for various vegetation types, different soil moisture contents and different-depth unsaturated soil. The results show that the cohesion of unsaturated soil changes greatly, and the friction angle changes a little with soil moisture content. It is also shown that vegetation can improve shear strength of unsaturated soil, which therefore provides a basis that vegetation can reinforce soil and protect slopes.

  16. Wall to Wall Optimal Transport

    Hassanzadeh, Pedram; Doering, Charles R


    The calculus of variations is employed to find steady divergence-free velocity fields that maximize transport of a tracer between two parallel walls held at fixed concentration for one of two constraints on flow strength: a fixed value of the kinetic energy or a fixed value of the enstrophy. The optimizing flows consist of an array of (convection) cells of a particular aspect ratio Gamma. We solve the nonlinear Euler-Lagrange equations analytically for weak flows and numerically (and via matched asymptotic analysis in the fixed energy case) for strong flows. We report the results in terms of the Nusselt number Nu, a dimensionless measure of the tracer transport, as a function of the Peclet number Pe, a dimensionless measure of the energy or enstrophy of the flow. For both constraints the maximum transport Nu_{MAX}(Pe) is realized in cells of decreasing aspect ratio Gamma_{opt}(Pe) as Pe increases. For the fixed energy problem, Nu_{MAX} \\sim Pe and Gamma_{opt} \\sim Pe^{-1/2}, while for the fixed enstrophy scen...

  17. Conditioned Reinforcement and Response Strength

    Shahan, Timothy A


    Stimuli associated with primary reinforcers appear themselves to acquire the capacity to strengthen behavior. This paper reviews research on the strengthening effects of conditioned reinforcers within the context of contemporary quantitative choice theories and behavioral momentum theory. Based partially on the finding that variations in parameters of conditioned reinforcement appear not to affect response strength as measured by resistance to change, long-standing assertions that conditioned reinforcers do not strengthen behavior in a reinforcement-like fashion are considered. A signposts or means-to-an-end account is explored and appears to provide a plausible alternative interpretation of the effects of stimuli associated with primary reinforcers. Related suggestions that primary reinforcers also might not have their effects via a strengthening process are explored and found to be worthy of serious consideration. PMID:20885815

  18. Flooding Effect on Earth Walls

    Meysam Banimahd


    Full Text Available Earth building is a sustainable, environmentally friendly and economical method of construction that has been used worldwide for many centuries. For the past three decades, earth has seen a revival as a building material for a modern construction method due to its benefits in terms of low carbon content, low cost and energy involved during construction, as well as the fact that it is a sustainable technology of building. Climate change is influencing precipitation levels and patterns around the world, and as a consequence, flood risk is increasing rapidly. When flooding occurs, earth buildings are exposed to water by submersion, causing an increase in the degree of saturation of the earth structures and therefore a decrease of the suction between particles. This study investigated the effect of cycles of flooding (consecutive events of flooding followed by dry periods on earth walls. A series of characterization tests were carried out to obtain the physical and mechanical properties of the studied earth material. In a second stage, Flooding Simulation Tests (FST were performed to explore the earth walls’ response to repeated flooding events. The results obtained for the tested earth wall/samples with reinforced material (straw reveal hydraulic hysteresis when wall/samples are subject to cycles of wetting and drying.

  19. Mechanically reinforced glass beams

    Nielsen, Jens Henrik; Olesen, John Forbes


    The use of glass as a load carrying material in structural elements is rarely seen even though glass is a popular material for many architects. This is owed to the unreliable and low tensile strength, which is due to surface flaws and high brittleness of the material. These properties lead...... to breakage without any warning or ductility, which can be catastrophic if no precautions are taken. One aspect of this issue is treated here by looking at the possibility of mechanically reinforcing glass beams in order to obtain ductile failure for such a structural component. A mechanically reinforced...... laminated float glass beam is constructed and tested in four-point bending. The beam consist of 4 layers of glass laminated together with a slack steel band glued onto the bottom face of the beam. The glass parts of the tested beams are \\SI{1700}{mm} long and \\SI{100}{mm} high, and the total width of one...

  20. Nanostructured composite reinforced material

    Seals, Roland D [Oak Ridge, TN; Ripley, Edward B [Knoxville, TN; Ludtka, Gerard M [Oak Ridge, TN


    A family of materials wherein nanostructures and/or nanotubes are incorporated into a multi-component material arrangement, such as a metallic or ceramic alloy or composite/aggregate, producing a new material or metallic/ceramic alloy. The new material has significantly increased strength, up to several thousands of times normal and perhaps substantially more, as well as significantly decreased weight. The new materials may be manufactured into a component where the nanostructure or nanostructure reinforcement is incorporated into the bulk and/or matrix material, or as a coating where the nanostructure or nanostructure reinforcement is incorporated into the coating or surface of a "normal" substrate material. The nanostructures are incorporated into the material structure either randomly or aligned, within grains, or along or across grain boundaries.

  1. South Oregon Coast Reinforcement.

    United States. Bonneville Power Administration.


    The Bonneville Power Administration is proposing to build a transmission line to reinforce electrical service to the southern coast of Oregon. This FYI outlines the proposal, tells how one can learn more, and how one can share ideas and opinions. The project will reinforce Oregon`s south coast area and provide the necessary transmission for Nucor Corporation to build a new steel mill in the Coos Bay/North Bend area. The proposed plant, which would use mostly recycled scrap metal, would produce rolled steel products. The plant would require a large amount of electrical power to run the furnace used in its steel-making process. In addition to the potential steel mill, electrical loads in the south Oregon coast area are expected to continue to grow.

  2. Reinforced Airfoil Shaped Body


    The present invention relates to an airfoil shaped body with a leading edge and a trailing edge extending along the longitudinal extension of the body and defining a profile chord, the airfoil shaped body comprising an airfoil shaped facing that forms the outer surface of the airfoil shaped body...... and surrounds an internal volume of the body, a distance member that is connected to the facing inside the body and extends from the facing and into the internal volume of the body, and at least one reinforcing member that operates in tension for reinforcing the facing against inward deflections...... and that is connected to the facing inside the internal volume of the body at the same side of the profile chord as the connection of the distance member to the facing and to the distance member at a distance from the facing....

  3. Reinforcement learning with Marr.

    Niv, Yael; Langdon, Angela


    To many, the poster child for David Marr's famous three levels of scientific inquiry is reinforcement learning-a computational theory of reward optimization, which readily prescribes algorithmic solutions that evidence striking resemblance to signals found in the brain, suggesting a straightforward neural implementation. Here we review questions that remain open at each level of analysis, concluding that the path forward to their resolution calls for inspiration across levels, rather than a focus on mutual constraints.

  4. Fiber reinforced polypropylene nanocomposites


    The aim of this thesis is to assess the feasibility of integrating nanoparticles into glass fiber (GF) reinforced isotactic polypropylene (iPP) composites via existing thermoplastic processing routes, and to investigate whether this results in significant improvements in the mechanical properties of the final composites. A longer term aim will be to extend the approach to the preparation of hybrid composites with added non-structural functionality. However, the nanoparticles that have provide...

  5. Fiber reinforced polypropylene nanocomposites


    The aim of this thesis is to assess the feasibility of integrating nanoparticles into glass fiber (GF) reinforced isotactic polypropylene (iPP) composites via existing thermoplastic processing routes, and to investigate whether this results in significant improvements in the mechanical properties of the final composites. A longer term aim will be to extend the approach to the preparation of hybrid composites with added non-structural functionality. However, the nanoparticles that have provide...

  6. The Community Reinforcement Approach.

    Meyers, Robert J; Smith, Jane Ellen; Lash, Denise N


    This chapter reviews two behavioral substance abuse treatments: The Community Reinforcement Approach (CRA) and Community Reinforcement and Family Training (CRAFT). Both of these programs were built on the concept that an individual's recovery is greatly affected by his or her unique environment. This environment, or reinforcing "community," is composed of family, friends, work/school, social activities, and perhaps spiritual affiliations. CRA, the first of these two programs to be developed, was created specifically for the problem drinker (Hunt & Azrin, 1973). The goal of CRA is to rearrange multiple aspects of an individual's "community" so that a clean and sober lifestyle is more rewarding than one that is dominated by alcohol and drugs. Subsequently, CRAFT was developed for the many individuals with substance abuse problems who are vehemently opposed to treatment (Institute of Medicine, 1990). CRAFT works through concerned family members and friends of these treatment refusers in an effort to get them to seek therapy (Sisson & Azrin, 1986). Descriptions and the empirical support for CRA and CRAFT follow.

  7. Reinforcement Learning Trees.

    Zhu, Ruoqing; Zeng, Donglin; Kosorok, Michael R

    In this paper, we introduce a new type of tree-based method, reinforcement learning trees (RLT), which exhibits significantly improved performance over traditional methods such as random forests (Breiman, 2001) under high-dimensional settings. The innovations are three-fold. First, the new method implements reinforcement learning at each selection of a splitting variable during the tree construction processes. By splitting on the variable that brings the greatest future improvement in later splits, rather than choosing the one with largest marginal effect from the immediate split, the constructed tree utilizes the available samples in a more efficient way. Moreover, such an approach enables linear combination cuts at little extra computational cost. Second, we propose a variable muting procedure that progressively eliminates noise variables during the construction of each individual tree. The muting procedure also takes advantage of reinforcement learning and prevents noise variables from being considered in the search for splitting rules, so that towards terminal nodes, where the sample size is small, the splitting rules are still constructed from only strong variables. Last, we investigate asymptotic properties of the proposed method under basic assumptions and discuss rationale in general settings.

  8. Autologous adventitial overlay method reinforces anastomoses in aortic surgery.

    Minato, Naoki; Okada, Takayuki; Sumida, Tomohiko; Watanabe, Kenichi; Maruyama, Takahiro; Kusunose, Takashi


    In this study, we present an inexpensive and effective method for providing a secure and hemostatic anastomosis using autologous adventitia obtained from a dissected or aneurysmal wall. The resected aortic wall is separated between the adventitia and media, and a soft, 2 × 10-cm adventitial strip is overlaid to cover the anastomotic margin. A graft is sutured to the aortic stump. This autologous adventitial overlay method can inexpensively and strongly reinforce the anastomosis during aortic surgery for dissection or aneurysm and will contribute to anastomotic hemostasis and long-term stability.

  9. Surface Heave Behaviour of Coir Geotextile Reinforced Sand Beds

    Lal, Dharmesh; Sankar, N.; Chandrakaran, S.


    Soil reinforcement by natural fibers is one of the cheapest and attractive ground improvement techniques. Coir is the most abundant natural fiber available in India and due to its high lignin content; it has a larger life span than other natural fibers. It is widely used in India for erosion control purposes, but its use as a reinforcement material is rather limited. This study focuses on the use of coir geotextile as a reinforcement material to reduce surface heave phenomena occurring in shallow foundations. This paper presents the results of laboratory model tests carried out on square footings supported on coir geotextile reinforced sand beds. The influence of various parameters such as depth of reinforcement, length, and number of layers of reinforcement was studied. It was observed that surface heave is considerably reduced with the provision of geotextile. Heave reduction up to 98.7% can be obtained by the proposed method. Heave reduction is quantified by a non-dimensional parameter called heave reduction factor.

  10. Design Aspect of including Infill Wall in RC Frame Design*

    Sukrawa, M.


    Full Text Available This study compares analysis and design of a four story reinforced concrete (RC frame structure with infill wall at upper levels and open at basement level. For the analysis, the RC frame are modeled as open frame (MOF and infilled-frames using six compression only cross diagonal strut (MIF-Strut, and infilled frame using shell elements (MIF-Shell. Another model, MIF-Full, is created by adding walls at basement level of the MIF-Strut to study the effect of wall discontinuity. All three dimensional models are loaded with gravity load and quake load appropriate for South Bali region. Results show that the infilled-frame models are 4.8 times stiffer than MOF in the wall direction. Perpendicular to the wall, however, the stiffness increase is 29%. Soft storey mechanism exists in the absence of wall at basement level, regardless of reasonable column dimensions.

  11. As-Fabricated Reinforced Carbon/Carbon Characterized

    Jacobson, Nathan S.; Calomino, Anthony M.; Webster, Neal


    Reinforced carbon/carbon (RCC) is a critical material for the space shuttle orbiter. It is used on the wing leading edge and the nose cap, where maximum temperatures are reached on reentry. The existing leading-edge system is a single-plate RCC composite construction with a wall thickness of approximately 1/4 in., making it a prime reliant protection scheme for vehicle operation.

  12. The 2011 Earthquake in Simav, Turkey and Seismic Damage to Reinforced Concrete Buildings

    Yücel Güney


    Full Text Available Reinforced concrete buildings suffered significant damage in the region affected by the 29 May 2011 earthquake in Simav (Kutahya, Turkey. Typical building damage is classified and potential causes of damage are investigated. Reinforced concrete moment resisting frames with hollow brick infill walls are the most common structural system in and around the Simav city center while masonry construction is common in rural areas. Although the Simav earthquake, with a magnitude of 5.7 to 5.9, can be classified as a moderate earthquake, many buildings experienced damage varying from frequent diagonal cracking and brittle failure of infill walls to collapse or severe damage to frames due to short columns, soft stories or other reasons including insufficient or poor detailing of reinforcement. This study investigates and presents the seismicity of the region, characteristics of the measured ground motions, seismic load demands including response spectra, and damage mechanisms, potential causes and classification of observed damage in reinforced concrete buildings.

  13. [Reinforcement learning by striatum].

    Kunisato, Yoshihiko; Okada, Go; Okamoto, Yasumasa


    Recently, computational models of reinforcement learning have been applied for the analysis of neuroimaging data. It has been clarified that the striatum plays a key role in decision making. We review the reinforcement learning theory and the biological structures such as the brain and signals such as neuromodulators associated with reinforcement learning. We also investigated the function of the striatum and the neurotransmitter serotonin in reward prediction. We first studied the brain mechanisms for reward prediction at different time scales. Our experiment on the striatum showed that the ventroanterior regions are involved in predicting immediate rewards and the dorsoposterior regions are involved in predicting future rewards. Further, we investigated whether serotonin regulates both the reward selection and the striatum function are specialized reward prediction at different time scales. To this end, we regulated the dietary intake of tryptophan, a precursor of serotonin. Our experiment showed that the activity of the ventral part of the striatum was correlated with reward prediction at shorter time scales, and this activity was stronger at low serotonin levels. By contrast, the activity of the dorsal part of the striatum was correlated with reward prediction at longer time scales, and this activity was stronger at high serotonin levels. Further, a higher proportion of small reward choices, together with a higher rate of discounting of delayed rewards is observed in the low-serotonin condition than in the control and high-serotonin conditions. Further examinations are required in future to assess the relation between the disturbance of reward prediction caused by low serotonin and mental disorders related to serotonin such as depression.


    张小龙; 刘宝臣; 吴名江; 李颖


    The paper proposes a new method of reinforcing deep and thick silt. The method uses the short-range and over-loading vacuum preloading dynamic drainage consolidation approach. It is based on the conclusion of soft soil drainage consolidation of S-T roundabout regularities. It is developed according to the characteristics of deep and thick silt soft soil in coastal areas and the requirements of engineering construction's substantial results. The approach also demonstrates that the primary consolidation settlement of deep and thick silt soft soil can be accomplished in a short time, under the optional regrouping of vacuum negative pressure and over-loading positive pressure as well as dynamic impact. The silt soft soil consolidation and settlement are capable of improving the intensity of the solid body while the ground surface dredged fill can become over-consolidating hard shell course under the dynamic impact. The consolidation of deep and thick silt soft soil can meet the requirements of ground bearing capacityand effectively control past-construction settlement and uneven settlement. The case study and the analysis as well asthe assessment of the effect of groundwork dealings show the feasibility and validity of this new method. It providesa new way of reinforcing deep and thick silt soft soil groundwork widely spread in coastal areas.%针对沿海地区深厚淤泥软土的特点和工程建设时效性的要求,本文在总结软土排水固结S-T曲线规律的基础上提出应用短程超载真空预压动力排水固结法加固深厚淤泥的方法,发现深厚淤泥软土在真空负压、超载正压和动力冲击三者优化组合的作用下,主固结沉降可在短时间内完成,土体强度提高的同时地表吹填土在动力冲击作用下形成超固结的硬壳层.深厚淤泥软土加固后能够满足地基承载力的要求并且能够有效控制工后沉降和不均匀沉降.并通过工程实例,对地基处理后的效果进行分析

  15. Manifold Regularized Reinforcement Learning.

    Li, Hongliang; Liu, Derong; Wang, Ding


    This paper introduces a novel manifold regularized reinforcement learning scheme for continuous Markov decision processes. Smooth feature representations for value function approximation can be automatically learned using the unsupervised manifold regularization method. The learned features are data-driven, and can be adapted to the geometry of the state space. Furthermore, the scheme provides a direct basis representation extension for novel samples during policy learning and control. The performance of the proposed scheme is evaluated on two benchmark control tasks, i.e., the inverted pendulum and the energy storage problem. Simulation results illustrate the concepts of the proposed scheme and show that it can obtain excellent performance.

  16. Negative effects of positive reinforcement

    Perone, Michael


    Procedures classified as positive reinforcement are generally regarded as more desirable than those classified as aversive—those that involve negative reinforcement or punishment. This is a crude test of the desirability of a procedure to change or maintain behavior. The problems can be identified on the basis of theory, experimental analysis, and consideration of practical cases. Theoretically, the distinction between positive and negative reinforcement has proven difficult (some would say t...

  17. How the deposition of cellulose microfibrils builds cell wall architecture

    Emons, A.M.C.; Mulder, B.M.


    Cell walls, the extracytoplasmic matrices of plant cells, consist of an ordered array of cellulose microfibrils embedded in a matrix of polysaccharides and glycoproteins. This construction is reminiscent of steel rods in reinforced concrete. How a cell organizes these ordered textures around itself,

  18. Experimental Investigation and Analytical Modeling of Prefabricated Reinforced Concrete Sandwich Panels

    BOURNAS DIONYSIOS; TORRISI Gonzalo; CRISAFULLI Francisco; Pavese, Alberto


    The behavior of prefabricated reinforced concrete sandwich panels (RCSPs) was investigated experimentally and analytically in this study. Initially, tests were carried out on single full-scale RCSPs with or without openings, reproducing the behavior of lateral resisting cantilever and fixed-end walls. The performance and failure mode of all panels tested revealed coupling between the flexure and shear response. However due to their well-detailed reinforcement, all panels exhibited a relativel...

  19. [The systems process of reinforcement].

    Sudakov, K V


    The process of reinforcement is considered in the context of the general theory of functional systems as an important part of behavioural act organization closely interacting with the dominant motivation. It is shown that reinforcement substantially changes the activities of separate neurons in different brain structures involved in dominant motivation. After a preliminary reinforcement under the influence of corresponding motivation the ribosomal apparatus of neurons begins to synthesize special molecular engrams of the action acceptor. The sensory mechanisms of reinforcement and, especially, the role of emotions are considered in details in the paper.

  20. Visualization of soil arching in flexible piled embankments

    Tuğba Eskışar


    Piled embankments rely on soil arching, but, when geogrid reinforcements are used, membrane action within the reinforcement contributes to load distribution. The arching of soil in unreinforced and reinforced piled embankments is evaluated in this study. A small-scale test apparatus is used to model the settlement up to 5 mm in an embankment with four pile elements. Visual inspection of the soil settlement and soil-reinforcement interaction is important to explain the mechanism of arching. In this study, X-ray Computed Tomography (CT) method was used as a non-destructive technique. The arching of soil between the piles was observed in the case of rigid piles and in the case of flexible piles with grid type of reinforcement. The load carrying capacity increased up to 33% in the case of geogrid reinforcement, and the differential settlement decreased around 35%, proving the efficiency of piled embankments with geogrid reinforcements. It is also shown that, using X-ray CT method and visualization techniques provides a better understanding of soil behavior in a reinforced embankment with the flexible pile foundation system.


    Ofrikhter Vadim Grigor’evich


    Full Text Available Natural non-treated sand reinforced with randomly oriented short polypropylene fibers of 12 mm in length was tested to determine creep characteristics. This study is a part of the research aimed at encouraging fibrosand (FRS application in subsoils, embankments and retaining wall constructions. Fiber content was accounted for 0.93 %. Twin specimens were put to creep tests (1-D compression using the two curve method. The test results were analyzed and checked with the use of ageing, hardening and hereditary creep theories. On the basis of approximation of the test results the creep deformation equation at constant stress for tested fibrosand was obtained. The assessment of fibrosand secondary compression was carried out by the FORE method. As a result, the value of the void ratio by the end of the secondary compression had been eu=0.7041. For determination of the beginning of the secondary compression the rate equation was superimposed on the empirical curve. The point of the graph divergence is the beginning of the secondary compression process. The secondary compression had begun by the time moment being equal to 9360 min. The void ratio by the beginning of the secondary compression had amounted to 0.70574. Fibrosand is a specific type of improved soil relating to so-called pseudo-cohesive soil. This type of soil is characterized by cohesion like cohesive soils, but, at the same time, by the filtration coefficient of about 1 m per day like non-cohesive soils. Pseudo-cohesive soil testing helps to understand the distinctive features of the stress-strain state of this kind of materials. Municipal solid waste also relates to them.

  2. 框支剪力墙土-结构共同作用的抗震性能分析%Antiseismic performance analysis for co-interaction of soil-structure of frame-supported shear wall

    陆铁坚; 单晓菲; 蔡勇


    采用有限元法对一框支剪力墙土-结构体系进行动力弹塑性时程分析.通过对计算模型的自振特性以及地震作用下的位移、层间位移角、等效刚度比和剪力等数据进行分析研究.研究结果表明:运用 ANSYS 建立框支剪力墙-土-结构共同作用模型对结构进行地震反应分析,能够真实地反映结构的抗震性能.转换层位置对结构自振周期影响较小;转换层附近的层间位移角和剪力均发生突变,且随转换层位置的提高而加剧;层间位移角较大值集中在结构中上部;框支柱剪力最大值发生在转换层中柱.建议抗震设计时,转换层位置可适当提高但不宜超过5层,等效侧向刚度比宜控制在0.8~1.3,除了底部框支柱加强外,还应该对中上部楼层采取减小层间位移的措施,对转换层中柱采取特殊加强.%A finite element elasto - plastic time - history analysis was conducted on the interaction system of soil - structure of frame - supported shear wall. The data of free vibration characteristics of models and the displacement, inter- storey drift angle, the ratio of equivalent lateral stiffness and shear force under earthquake were studied. The results show that, using models built in ANSYS to analyze the seismic response of SSI structure of frame - supported shear wall can efficiently reflect the seismic performance of structure. The location of conversion floor has little effect on the natural period of vibration mode. The drift angle and shear near conversion layer had mutations, which intensified with the increase of conversion layer position. The higher the level of transfer stories, the larger the ratio of equivalent lateral stiffness is. The larger inter - storey drift angle of structure occurs in middle - upper part. The maximum shear force of columns appears in the middle columns on transfer storey. The height of transfer storey can be set a little higher properly but not more than 5 layer

  3. Recycling of Reinforced Plastics

    Adams, R. D.; Collins, Andrew; Cooper, Duncan; Wingfield-Digby, Mark; Watts-Farmer, Archibald; Laurence, Anna; Patel, Kayur; Stevens, Mark; Watkins, Rhodri


    This work has shown is that it is possible to recycle continuous and short fibre reinforced thermosetting resins while keeping almost the whole of the original material, both fibres and matrix, within the recyclate. By splitting, crushing hot or cold, and hot forming, it is possible to create a recyclable material, which we designate a Remat, which can then be used to remanufacture other shapes, examples of plates and tubes being demonstrated. Not only can remanufacturing be done, but it has been shown that over 50 % of the original mechanical properties, such as the E modulus, tensile strength, and interlaminar shear strength, can be retained. Four different forms of composite were investigated, a random mat Glass Fibre Reinforced Plastic (GFRP) bathroom component and boat hull, woven glass and carbon fibre cloth impregnated with an epoxy resin, and unidirectional carbon fibre pre-preg. One of the main factors found to affect composite recyclability was the type of resin matrix used in the composite. Thermoset resins tested were shown to have a temperature range around the Glass Transition Temperature (Tg) where they exhibit ductile behaviour, hence aiding reforming of the material. The high-grade carbon fibre prepreg was found to be less easy to recycle than the woven of random fibre laminates. One method of remanufacturing was by heating the Remat to above its glass transition temperature, bending it to shape, and then cooling it. However, unless precautions are taken, the geometric form may revert. This does not happen with the crushed material.

  4. Quantum reinforcement learning.

    Dong, Daoyi; Chen, Chunlin; Li, Hanxiong; Tarn, Tzyh-Jong


    The key approaches for machine learning, particularly learning in unknown probabilistic environments, are new representations and computation mechanisms. In this paper, a novel quantum reinforcement learning (QRL) method is proposed by combining quantum theory and reinforcement learning (RL). Inspired by the state superposition principle and quantum parallelism, a framework of a value-updating algorithm is introduced. The state (action) in traditional RL is identified as the eigen state (eigen action) in QRL. The state (action) set can be represented with a quantum superposition state, and the eigen state (eigen action) can be obtained by randomly observing the simulated quantum state according to the collapse postulate of quantum measurement. The probability of the eigen action is determined by the probability amplitude, which is updated in parallel according to rewards. Some related characteristics of QRL such as convergence, optimality, and balancing between exploration and exploitation are also analyzed, which shows that this approach makes a good tradeoff between exploration and exploitation using the probability amplitude and can speedup learning through the quantum parallelism. To evaluate the performance and practicability of QRL, several simulated experiments are given, and the results demonstrate the effectiveness and superiority of the QRL algorithm for some complex problems. This paper is also an effective exploration on the application of quantum computation to artificial intelligence.

  5. Lock Wall Expedient Repair Demonstration Monitoring, John T. Myers Locks and Dam, Ohio River


    reinforced polymer composites for making repairs to hydraulic navigation structures. At the time of publication of this report, COL Kevin J. Wilson...thermoplastic guide wall and deck floating pontoon at the Port Allen navigation lock in Louisiana, (e) tongue and groove vertical plank walls, (f

  6. Nondestructive testing of externally reinforced structures for seismic retrofitting using flax fiber reinforced polymer (FFRP) composites

    Ibarra-Castanedo, C.; Sfarra, S.; Paoletti, D.; Bendada, A.; Maldague, X.


    Natural fibers constitute an interesting alternative to synthetic fibers, e.g. glass and carbon, for the production of composites due to their environmental and economic advantages. The strength of natural fiber composites is on average lower compared to their synthetic counterparts. Nevertheless, natural fibers such as flax, among other bast fibers (jute, kenaf, ramie and hemp), are serious candidates for seismic retrofitting applications given that their mechanical properties are more suitable for dynamic loads. Strengthening of structures is performed by impregnating flax fiber reinforced polymers (FFRP) fabrics with epoxy resin and applying them to the component of interest, increasing in this way the load and deformation capacities of the building, while preserving its stiffness and dynamic properties. The reinforced areas are however prompt to debonding if the fabrics are not mounted properly. Nondestructive testing is therefore required to verify that the fabric is uniformly installed and that there are no air gaps or foreign materials that could instigate debonding. In this work, the use of active infrared thermography was investigated for the assessment of (1) a laboratory specimen reinforced with FFRP and containing several artificial defects; and (2) an actual FFRP retrofitted masonry wall in the Faculty of Engineering of the University of L'Aquila (Italy) that was seriously affected by the 2009 earthquake. Thermographic data was processed by advanced signal processing techniques, and post-processed by computing the watershed lines to locate suspected areas. Results coming from the academic specimen were compared to digital speckle photography and holographic interferometry images.

  7. Corrosion of reinforcement bars in steel ibre reinforced concrete structures

    Solgaard, Anders Ole Stubbe

    Steel fibres have been known as an alternative to traditional reinforcement bars for special applications of structural concrete for decades and the use of steel fibre reinforced concrete (SFRC) has gradually increased in recent years. Steel fibres lead to reduced crack widths in concrete formed......, among other reasons, due to shrinkage and/or mechanical loading. Steel fibres are nowadays also used in combination with traditional reinforcement for structural concrete, where the role of the fibres is to minimize the crack widths whereas the traditional reinforcement bars are used for structural....... The aim of the work presented in this Ph.D. thesis was to quantify the influence of steel fibres on corrosion of traditional reinforcement bars embedded in uncracked concrete as well as cracked concrete. Focus of the work was set on the impact of steel fibres on corrosion propagation in uncracked concrete...

  8. Be Aware of Negative Reinforcement.

    Cipani, Ennio C.


    This article examines the concept of negative reinforcement in relation to the maintenance of off-task and disruptive behaviors in classrooms. Suggestions are given for determining whether negative reinforcement (in the form of escape from the instructional task) or teacher attention is maintaining the behavior. Suggestions for making tasks less…

  9. Stochastic Reinforcement Benefits Skill Acquisition

    Dayan, Eran; Averbeck, Bruno B.; Richmond, Barry J.; Cohen, Leonardo G.


    Learning complex skills is driven by reinforcement, which facilitates both online within-session gains and retention of the acquired skills. Yet, in ecologically relevant situations, skills are often acquired when mapping between actions and rewarding outcomes is unknown to the learning agent, resulting in reinforcement schedules of a stochastic…

  10. A systems process of reinforcement.

    Sudakov, K V


    Functional systems theory was used to consider the process of reinforcement of the actions on the body of reinforcing factors, i.e., the results of behavior satisfying the body's original needs. The systems process of reinforcement includes reverse afferentation entering the CNS from receptors acted upon by various parameters of the desired results, and mechanisms for comparing reverse afferentation with the apparatus which accepts the results of the action and the corresponding emotional component. A tight interaction between reinforcement and the dominant motivation is generated on the basis of the hologram principle. Reinforcement forms an apparatus for predicting a desired result, i.e. a result-of-action acceptor. Reinforcement procedures significant changes in the activities of individual neurons in the various brain structures involved in dominant motivation, transforming their spike activity for a burst pattern to regular discharges; there are also molecular changes in neuron properties. After preliminary reinforcement, the corresponding motivation induces the ribosomal system of neurons to start synthesizing special effector molecules, which organize molecular engrams of the acceptor of the action's result. Sensory mechanisms of reinforcement are considered, with particular reference to the information role of emotions.

  11. Reinforcement Learning Through Gradient Descent


    Reinforcement learning is often done using parameterized function approximators to store value functions. Algorithms are typically developed for...practice of existing types of algorithms, the gradient descent approach makes it possible to create entirely new classes of reinforcement learning algorithms

  12. Corrosion Inhibitors for Reinforced Concrete

    ECT Team, Purdue


    Steel corrosion in reinforced concrete structures has been a major problem across the U.S. Steel-reinforced concrete structures are continually subject to attack by corrosion brought on by naturally occurring environmental conditions. FerroGard, a corrosion inhibitor, developed by Sika Corporation, penetrates hardened concrete to dramatically reduce corrosion by 65% and extend the structure's service life.

  13. Diagnosis And Prescription: Reinforcement Module.

    Fair, George W.

    This learning module has been designed to aid the teacher trainee in identifying ways in which he influences student behavior in the classroom and also explores means of selecting more meaningful reinforcers and their application. Terminal objectives of the module are the ability to (1) define the terms "reinforcement,""positive…

  14. Conditioned Reinforcement and Response Strength

    Shahan, Timothy A.


    Stimuli associated with primary reinforcers appear themselves to acquire the capacity to strengthen behavior. This paper reviews research on the strengthening effects of conditioned reinforcers within the context of contemporary quantitative choice theories and behavioral momentum theory. Based partially on the finding that variations in…

  15. Stabilized Lateritic Blocks Reinforced With Fibrous Coir Wastes

    M G Sreekumar


    Full Text Available Tropical countries are rich in lateritic soil, a naturally available raw material for building construction. But its potential in block making is not yet satisfactorily explored. This paper focuses on an experimental investigation for improvising stabilized lateritic blocks (SLB with coir cutting wastes from coir industry as reinforcing elements. Lateritic soil used in this study showed a higher percentage of clay content. Hence it was pre-stabilized with sand and cement. Blocks were prepared by stabilizing it further with waste fibrous additives and tested for strength and durability. Considerable improvement in strength (compressive strength @19% and tensile strength @ 9% and durability characteristics were exhibited by the new fiber reinforced lateritic blocks (FRLB with fiber content of 0.5%. These blocks can be successfully proposed for load bearing construction and as well as for earthquake resistant structures

  16. Bond characteristics of steel fiber and deformed reinforcing steel bar embedded in steel fiber reinforced self-compacting concrete (SFRSCC)

    Aslani, Farhad; Nejadi, Shami


    Steel fiber reinforced self-compacting concrete (SFRSCC) is a relatively new composite material which congregates the benefits of the self-compacting concrete (SCC) technology with the profits derived from the fiber addition to a brittle cementitious matrix. Steel fibers improve many of the properties of SCC elements including tensile strength, ductility, toughness, energy absorption capacity, fracture toughness and cracking. Although the available research regarding the influence of steel fibers on the properties of SFRSCC is limited, this paper investigates the bond characteristics between steel fiber and SCC firstly. Based on the available experimental results, the current analytical steel fiber pullout model (Dubey 1999) is modified by considering the different SCC properties and different fiber types (smooth, hooked) and inclination. In order to take into account the effect of fiber inclination in the pullout model, apparent shear strengths (τ (app)) and slip coefficient (β) are incorporated to express the variation of pullout peak load and the augmentation of peak slip as the inclined angle increases. These variables are expressed as functions of the inclined angle (ϕ). Furthurmore, steel-concrete composite floors, reinforced concrete floors supported by columns or walls and floors on an elastic foundations belong to the category of structural elements in which the conventional steel reinforcement can be partially replaced by the use of steel fibers. When discussing deformation capacity of structural elements or civil engineering structures manufactured using SFRSCC, one must be able to describe thoroughly both the behavior of the concrete matrix reinforced with steel fibers and the interaction between this composite matrix and discrete steel reinforcement of the conventional type. However, even though the knowledge on bond behavior is essential for evaluating the overall behavior of structural components containing reinforcement and steel fibers

  17. Dynamic load test of Arquin-designed CMU wall.

    Jensen, Richard Pearson


    The Arquin Corporation has developed a new method of constructing CMU (concrete masonry unit) walls. This new method uses polymer spacers connected to steel wires that serve as reinforcing as well as a means of accurately placing the spacers so that the concrete block can be dry stacked. The hollows of the concrete block are then filled with grout. As part of a New Mexico Small Business Assistance Program (NMSBA), Sandia National Laboratories conducted a series of tests that dynamically loaded wall segments to compare the performance of walls constructed using the Arquin method to a more traditional method of constructing CMU walls. A total of four walls were built, two with traditional methods and two with the Arquin method. Two of the walls, one traditional and one Arquin, had every third cell filled with grout. The remaining two walls, one traditional and one Arquin, had every cell filled with grout. The walls were dynamically loaded with explosive forces. No significant difference was noted between the performance of the walls constructed by the Arquin method when compared to the walls constructed by the traditional method.

  18. Negative effects of positive reinforcement.

    Perone, Michael


    Procedures classified as positive reinforcement are generally regarded as more desirable than those classified as aversive-those that involve negative reinforcement or punishment. This is a crude test of the desirability of a procedure to change or maintain behavior. The problems can be identified on the basis of theory, experimental analysis, and consideration of practical cases. Theoretically, the distinction between positive and negative reinforcement has proven difficult (some would say the distinction is untenable). When the distinction is made purely in operational terms, experiments reveal that positive reinforcement has aversive functions. On a practical level, positive reinforcement can lead to deleterious effects, and it is implicated in a range of personal and societal problems. These issues challenge us to identify other criteria for judging behavioral procedures.

  19. Renforcement de fondations superficielles par soil mixing : Analyses par modélisation physique et numérique

    Dhaybi, Mathieu


    The reinforcement of shallow foundations by soil mixing consists on mixing the soil beneath with a hydraulic binder in order to obtain columns with mixed modulus. These columns, which have mechanical properties bounded between those of concrete and those of soil, can improve the soil bearing capacity and reduce excessive settlements as well. This research work is a phenomenological and quantitative study of the behavior of shallow foundations reinforced by soil mixing columns. It leads to ana...

  20. Comparative study of Trombe wall, water wall and trans wall

    Sodha, M.S.; Bansal, N.K.; Singh, S.; Ram, S.; Annamalai, M.; Iyer, M.V.; Nirmala, K.A.; Venkatesh, P.; Prasad, C.R.; Subramani, C.


    The thermal performances of three systems viz. Trombe wall: (1) without; and (2) with vents (forced air circulation), water wall and Transwall have been studied analytically interms of heat flux entering the living space (Maintained at 20/sup 0/C) corresponding to the meteriological data on January 19, 1981 at New Delhi (India), a typical cold winter day. Subsequent parametric studies using the simulation indicated that the Transwall system is the more efficient system for the passive heating of buildings.

  1. Geotechnical methods of reinforcement of slopes near railroads

    Vladimir D.Vereskun; Victor A.Yavna


    In order to generate well-based design decisions on reinforcement of landslide slopes and road embankment slopes, a system of combined geotechnical analysis of geological conditions is suggested which includes topographic and geo-physical survey, and laboratory studies of soils using infra-red spectroscopy methods. Calculations of slopes' deflected modes are carried out with taking into account elastic and elasto-plastic behavior of soil, and the presence of supporting man-made constructions. Results of the application of the system suggested may be used as criteria for the classification of landslide slopes along permanent ways according to the degree of danger when used for transportation.

  2. Carbon Nanotubes Reinforced Composites for Biomedical Applications

    Wei Wang; Yuhe Zhu; Susan Liao; Jiajia Li


    This review paper reported carbon nanotubes reinforced composites for biomedical applications. Several studies have found enhancement in the mechanical properties of CNTs-based reinforced composites by the addition of CNTs. CNTs reinforced composites have been intensively investigated for many aspects of life, especially being made for biomedical applications. The review introduced fabrication of CNTs reinforced composites (CNTs reinforced metal matrix composites, CNTs reinforced polymer matr...

  3. Wall jets created by single and twin high pressure jet impingement

    Miller, P.; Wilson, M.


    An extensive experimental investigation into the nature of the wall jets produced by single and twin normal jet impingement has been undertaken. Wall jet velocity profiles have been recorded up to 70 jet diameters from the impingement point, at pressures representative of current VStol technology. The tests used fixed convergent nozzles, with nozzle height and spacing and jet pressure being varied. Single jet impingement displays a consistent effect of nozzle height on wall jet development. For twin jet cases a powerful reinforcement exists along the wall jet interaction plane. Remote from the interaction plane the wall jets are weaker than those produced by a single jet impingement.

  4. 高填方错台式加筋土边坡治理施工技术%Construction technology of steel reinforced soil slope treatment with high-filling embankment split-style



    Combining with engineering examples, the thesis introduces high-filling embankment split-style slope treatment construction principles. Starting from aspects of construction sampling, foundation excavation, bottom base treatment and reinforced-belt paving, it describes the slope treatment construction technology procedures, and puts forward quality examination measures, and finally points out its advantages, such as con-venient construction, no pollution, no noise and possessing great environment benefit as well.%结合工程实例,介绍了高填方错台式加筋土边坡治理施工原理,从施工放样、基础开挖、基底处理、筋带铺设等方面,阐述了该边坡治理方法的施工工艺流程,并提出了质量检查验收措施,指出该方法施工方便、无污染、无噪声,具有良好的环境效益.

  5. Shear Behavior of Concrete Beams Reinforced with GFRP Shear Reinforcement

    Heecheul Kim; Min Sook Kim; Myung Joon Ko; Young Hak Lee


    This paper presents the shear capacities of concrete beams reinforced with glass fiber reinforced polymer (GFRP) plates as shear reinforcement. To examine the shear performance, we manufactured and tested a total of eight specimens. Test variables included the GFRP strip-width-to-spacing ratio and type of opening array. The specimen with a GFRP plate with a 3×2 opening array showed the highest shear strength. From the test results, the shear strength increased as the strip-width-to-strip-spac...

  6. Interaction analysis of back-to-back mechanically stabilized earth walls

    Sadok Benmebarek; Samir Attallaoui; Naïma Benmebarek


    Back-to-back mechanically stabilized earth walls (BBMSEWs) are encountered in bridge approaches, ramp ways, rockfall protection systems, earth dams, levees and noise barriers. However, available design guidelines for BBMSEWs are limited and not applicable to numerical modeling when back-to-back walls interact with each other. The objective of this paper is to investigate, using PLAXIS code, the effects of the reduction in the distance between BBMSEW, the reinforcement length, the quality of backfill material and the connection of reinforcements in the middle, when the back-to-back walls are close. The results indicate that each of the BBMSEWs behaves independently if the width of the embankment between mechanically stabilized earth walls is greater than that of the active zone. This is in good agreement with the result of FHWA design guideline. However, the results show that the FHWA design guideline un-derestimates the lateral earth pressure when back-to-back walls interact with each other. Moreover, for closer BBMSEWs, FHWA design guideline strongly overestimates the maximum tensile force in the reinforcement. The investigation of the quality of backfill material shows that the minor increase in embankment cohesion can lead to significant reductions in both the lateral earth pressure and the maximum tensile force in geosynthetic. When the distance between the two earth walls is close to zero, the connection of reinforcement between back-to-back walls significantly improves the factor of safety.

  7. Interaction analysis of back-to-back mechanically stabilized earth walls

    Sadok Benmebarek


    Full Text Available Back-to-back mechanically stabilized earth walls (BBMSEWs are encountered in bridge approaches, ramp ways, rockfall protection systems, earth dams, levees and noise barriers. However, available design guidelines for BBMSEWs are limited and not applicable to numerical modeling when back-to-back walls interact with each other. The objective of this paper is to investigate, using PLAXIS code, the effects of the reduction in the distance between BBMSEW, the reinforcement length, the quality of backfill material and the connection of reinforcements in the middle, when the back-to-back walls are close. The results indicate that each of the BBMSEWs behaves independently if the width of the embankment between mechanically stabilized earth walls is greater than that of the active zone. This is in good agreement with the result of FHWA design guideline. However, the results show that the FHWA design guideline underestimates the lateral earth pressure when back-to-back walls interact with each other. Moreover, for closer BBMSEWs, FHWA design guideline strongly overestimates the maximum tensile force in the reinforcement. The investigation of the quality of backfill material shows that the minor increase in embankment cohesion can lead to significant reductions in both the lateral earth pressure and the maximum tensile force in geosynthetic. When the distance between the two earth walls is close to zero, the connection of reinforcement between back-to-back walls significantly improves the factor of safety.

  8. Seismic retrofitting of timber framed walls

    Gonçalves, A. M.


    Full Text Available After the 1755 earthquake that destroyed Lisbon, an innovative anti-seismic structural system was developed consisting of a timber skeleton, that included timber framed masonry walls. After more than 250 years these structures need rehabilitation to face the present demands. The research presented in this paper aimed at experimentally characterizing the cyclic behaviour of timber framed walls reinforced with three different methods, namely: (i elastic-plastic dampers on diagonal braces, (ii reinforcement of timber connections with steel plates, (iii application of a reinforced rendering. The elastic-plastic damper showed an unsymmetrical behaviour and some difficulties to implement in practice. The strengthening with reinforced render led to an initial stiffness increase but showed a limited deformation capacity. The walls with reinforcing steel plates at the timber connections showed the best behaviour in terms of strength, stiffness and energy dissipation.Después del terremoto de 1755 que destruyó Lisboa, un sistema estructural antisísmico muy innovador fue desarrollado. El sistema consistió en un esqueleto de madera, que incluyó la construcción de muros de mampostería con un entramado de madera. Transcurridos más de 250 años, estas estructuras necesitan rehabilitación para poder hacer frente a los requisitos estructurales actuales. La investigación presentada en este trabajo tiene como objetivo caracterizar experimentalmente el comportamiento cíclico de los muros con entramado de madera reforzados con tres métodos diferentes: (i amortiguadores elasto-plásticos, (ii refuerzo de las conexiones de madera con placas de acero, (iii aplicación de un mortero reforzado. El amortiguador elasto-plástico mostró un comportamiento asimétrico y algunas dificultades para aplicarlo en la práctica. El refuerzo con mortero reforzado condujo a un aumento de la rigidez inicial, pero reveló una capacidad de deformación limitada. Los muros con

  9. Domain Walls on Singularities

    Halyo, Edi


    We describe domain walls that live on $A_2$ and $A_3$ singularities. The walls are BPS if the singularity is resolved and non--BPS if it is deformed and fibered. We show that these domain walls may interpolate between vacua that support monopoles and/or vortices.

  10. The Lamportian cell wall

    Keiliszewski, M.; Lamport, D. (Michigan State Univ. Plant Research Lab., East Lansing (United States))


    The Lamportian Warp-Weft hypothesis suggests a cellulose-extensin interpenetrating network where extensin mechanically couples the load-bearing cellulose microfibrils in a wall matrix that is best described as a microcomposite. This model is based on data gathered from the extensin-rich walls of tomato and sycamore cell suspension culture, wherein extensin precursors are insolubilized into the wall by undefined crosslinks. The authors recent work with cell walls isolated from intact tissue as well as walls from suspension cultured cells of the graminaceous monocots maize and rice, the non-graminaceous monocot asparagus, the primitive herbaceous dicot sugar beet, and the gymnosperm Douglas Fir indicate that although extensins are ubiquitous to all plant species examined, they are not the major structural protein component of most walls examined. Amino acid analyses of intact and HF-treated walls shows a major component neither an HRGP, nor directly comparable to the glycine-rich wall proteins such as those associated with seed coat walls or the 67 mole% glycine-rich proteins cloned from petunia and soybean. Clearly, structural wall protein alternatives to extensin exist and any cell wall model must take that into account. If we assume that extracellular matrices are a priori network structures, then new Hypless' structural proteins in the maize cell wall raise questions about the sort of network these proteins create: the kinds of crosslinks involved; how they are formed; and the roles played by the small amounts of HRGPs.

  11. Halogenation of microcapsule walls

    Davis, T. R.; Schaab, C. K.; Scott, J. C.


    Procedure for halogenation of confining walls of both gelatin and gelatin-phenolic resin capsules is similar to that used for microencapsulation. Ten percent halogen content renders capsule wall nonburning; any higher content enhances flame-retardant properties of selected internal phase material. Halogenation decreases permeability of wall material to encapsulated materials.

  12. Preference pulses induced by reinforcement.

    Hachiga, Yosuke; Sakagami, Takayuki; Silberberg, Alan


    Eight rats responded on concurrent Variable-Ratio 20 Extinction schedules for food reinforcement. The assignment of variable-ratio reinforcement to a left or right lever varied randomly following each reinforcer, and was cued by illumination of a stimulus light above that lever. Postreinforcement preference levels decreased substantially and reliably over time when the lever that just delivered reinforcement was now in extinction; however, if that lever was once again associated with variable ratio, this decrease in same-lever preference tended to be small, and for some subjects, not in evidence. The changes in preference level to the extinction lever were well described by a modified version of Killeen, Hanson, and Osborne's (1978) induction model. Consistent with this model's attribution of preference change to induction, we attribute preference change in this report to a brief period of reinforcer-induced arousal that energizes responding to the lever that delivered the last reinforcer. After a few seconds, this induced responding diminishes, and the operant responding that remains comes under the control of the stimulus light cuing the lever providing variable-ratio reinforcement.

  13. Conditioned inhibition and reinforcement rate.

    Harris, Justin A; Kwok, Dorothy W S; Andrew, Benjamin J


    We investigated conditioned inhibition in a magazine approach paradigm. Rats were trained on a feature negative discrimination between an auditory conditioned stimulus (CS) reinforced at one rate versus a compound of that CS and a visual stimulus (L) reinforced at a lower rate. This training established L as a conditioned inhibitor. We then tested the inhibitory strength of L by presenting it in compound with other auditory CSs. L reduced responding when tested with a CS that had been reinforced at a high rate, but had less or even no inhibitory effect when tested with a CS that had been reinforced at a low rate. The inhibitory strength of L was greater if it signaled a decrease in reinforcement from an already low rate than if it signaled an equivalent decrease in reinforcement from a high rate. We conclude that the strength of inhibition is not a linear function of the change in reinforcement that it signals. We discuss the implications of this finding for models of learning (e.g., Rescorla & Wagner, 1972) that identify inhibition with a difference (subtraction) rule.

  14. Shear Behavior of Concrete Beams Reinforced with GFRP Shear Reinforcement

    Heecheul Kim


    Full Text Available This paper presents the shear capacities of concrete beams reinforced with glass fiber reinforced polymer (GFRP plates as shear reinforcement. To examine the shear performance, we manufactured and tested a total of eight specimens. Test variables included the GFRP strip-width-to-spacing ratio and type of opening array. The specimen with a GFRP plate with a 3×2 opening array showed the highest shear strength. From the test results, the shear strength increased as the strip-width-to-strip-spacing ratio increased. Also, we used the experimental results to evaluate whether the shear strength equations of ACI 318-14 and ACI 440.1R can be applied to the design of GFRP shear reinforcement. In the results, the ACI 440 equation underestimated the experimental results more than that of ACI 318.

  15. Machining of fiber reinforced composites

    Komanduri, Ranga; Zhang, Bi; Vissa, Chandra M.

    Factors involved in machining of fiber-reinforced composites are reviewed. Consideration is given to properties of composites reinforced with boron filaments, glass fibers, aramid fibers, carbon fibers, and silicon carbide fibers and to polymer (organic) matrix composites, metal matrix composites, and ceramic matrix composites, as well as to the processes used in conventional machining of boron-titanium composites and of composites reinforced by each of these fibers. Particular attention is given to the methods of nonconventional machining, such as laser machining, water jet cutting, electrical discharge machining, and ultrasonic assisted machining. Also discussed are safety precautions which must be taken during machining of fiber-containing composites.

  16. Reinforced Intrusion Detection Using Pursuit Reinforcement Competitive Learning

    Indah Yulia Prafitaning Tiyas


    Full Text Available Today, information technology is growing rapidly,all information can be obtainedmuch easier. It raises some new problems; one of them is unauthorized access to the system. We need a reliable network security system that is resistant to a variety of attacks against the system. Therefore, Intrusion Detection System (IDS required to overcome the problems of intrusions. Many researches have been done on intrusion detection using classification methods. Classification methodshave high precision, but it takes efforts to determine an appropriate classification model to the classification problem. In this paper, we propose a new reinforced approach to detect intrusion with On-line Clustering using Reinforcement Learning. Reinforcement Learning is a new paradigm in machine learning which involves interaction with the environment.It works with reward and punishment mechanism to achieve solution. We apply the Reinforcement Learning to the intrusion detection problem with considering competitive learning using Pursuit Reinforcement Competitive Learning (PRCL. Based on the experimental result, PRCL can detect intrusions in real time with high accuracy (99.816% for DoS, 95.015% for Probe, 94.731% for R2L and 99.373% for U2R and high speed (44 ms.The proposed approach can help network administrators to detect intrusion, so the computer network security systembecome reliable. Keywords: Intrusion Detection System, On-Line Clustering, Reinforcement Learning, Unsupervised Learning.

  17. Correlations Between Mechanical Properties of Steel Fiber Reinforced Concrete

    Carrillo Julián


    Full Text Available Tension strength and post-cracking deformation capacities that exhibits steel fiber reinforced concrete (SFRC stimulate its use in elements governed by shear deformations. Aimed at developing design aids that promote the use of SFRC as web shear reinforcement of concrete walls for low-rise economic housing (LEH, an experimental study for describing the mechanical properties of SFRC was carried out. The experimental program included testing of 128 cylinder- and beam-type specimens. According to requirements specified by ACI-318, to thickness of walls used in LEH, and to results of previous studies, three Dramix fibers with length-diameter ratios of 55, 64 and 80 were selected. Fiber dosage was expressed in terms of the minimum fiber dosage specified by ACI-318 for replacing the minimum area of conventional shear reinforcement in beams (60 kg/m3. Therefore, five dosages were used: 0, 40, 45, 60 and 75 kg/m3. Mechanical properties of SFRC under compressive, tensile and flexural stresses were evaluated in this study. Based on trends of experimental results, numerical correlations for estimating both basic mechanical properties and properties that describe flexural performance of SFRC are proposed.


    Mkrtychev Oleg Vartanovich


    Full Text Available The co-authors consider the problem of analysis of building structures in respect of combined effects of forces and temperatures. Results of fire tests of reinforced concrete walls and slabs are presented. Overview of the analysis of the fire resistance of reinforced-concrete buildings is also provided. As a result of the research, numerical solutions were obtained in respect of deflections, stresses, deformations and internal forces arising in a reinforced concrete bearing wall and plate exposed to a combination of forces and thermal loads. Comparative analysis of the experimental data and the results of the numerical solution was performed. The conclusion is that the experimental data are in good fit to the results of the numerical solution. Overall limit state of the monolithic building under consideration in terms of its fire resistance means its failure as a result of collapse. The limit state value is equal to 60; therefore, it is equal to 60 minutes. This value, if considered in respect of separate bearing elements, fits the fire resistance limit of buildings of Grade III (Fire Resistance that is equal to 45. Evidently, assurance of higher fire resistance limits of the building under consideration requires special fire safety actions to be applied.

  19. Methodical Specifics of Thermal Experiments with Thin Carbon Reinforced Plates

    O. V. Denisov


    Full Text Available Polymer composite materials (CM are widely used in creation of large space constructions, especially reflectors of space antennas. Composite materials should provide high level of specific stiffness and strength for space structures. Thermal conductivity in reinforcement plane is a significant factor in case of irregular heating space antennas. Nowadays, data on CM reinforcement plane thermal conductivity are limited and existing methods of its defining are imperfect. Basically, traditional methods allow us to define thermal conductivity in perpendicular direction towards the reinforcement plane on the samples of round or rectangular plate. In addition, the thickness of standard samples is larger than space antenna thickness. Consequently, new methods are required. Method of contact heating, which was developed by BMSTU specialists with long hollow carbon beam, could be a perspective way. This article is devoted to the experimental method of contact heating on the thin carbon plates.Thermal tests were supposed to provide a non-stationary temperature field with a gradient being co-directional with the plane reinforcement in the material sample. Experiments were conducted in vacuum chamber to prevent unstructured convection. Experimental thermo-grams processing were calculated by 1-d thermal model for a thin plate. Influence of uncertainty of experimental parameters, such as (radiation emission coefficients of sample surface, glue, temperature sensors and uncertainty of sensors placement on the result of defined thermal conductivity has been estimated. New data on the thermal conductivity in reinforcement plane were obtained within 295 - 375 K temperature range, which can be used to design and develop reflectors of precision space antennas. In the future it is expedient to conduct tests of thin-wall plates from carbon fiber-reinforced plastic in wide temperature range, especially in the low-range temperatures.

  20. Tungsten disulfide nanotubes reinforced biodegradable polymers for bone tissue engineering.

    Lalwani, Gaurav; Henslee, Allan M; Farshid, Behzad; Parmar, Priyanka; Lin, Liangjun; Qin, Yi-Xian; Kasper, F Kurtis; Mikos, Antonios G; Sitharaman, Balaji


    In this study, we have investigated the efficacy of inorganic nanotubes as reinforcing agents to improve the mechanical properties of poly(propylene fumarate) (PPF) composites as a function of nanomaterial loading concentration (0.01-0.2 wt.%). Tungsten disulfide nanotubes (WSNTs) were used as reinforcing agents in the experimental group. Single- and multi-walled carbon nanotubes (SWCNTs and MWCNTs) were used as positive controls, and crosslinked PPF composites were used as the baseline control. Mechanical testing (compression and three-point bending) shows a significant enhancement (up to 28-190%) in the mechanical properties (compressive modulus, compressive yield strength, flexural modulus and flexural yield strength) of WSNT-reinforced PPF nanocomposites compared to the baseline control. In comparison to the positive controls, significant improvements in the mechanical properties of WSNT nanocomposites were also observed at various concentrations. In general, the inorganic nanotubes (WSNTs) showed mechanical reinforcement better than (up to 127%) or equivalent to that of carbon nanotubes (SWCNTs and MWCNTs). Sol fraction analysis showed significant increases in the crosslinking density of PPF in the presence of WSNTs (0.01-0.2 wt.%). Transmission electron microscopy (TEM) analysis on thin sections of crosslinked nanocomposites showed the presence of WSNTs as individual nanotubes in the PPF matrix, whereas SWCNTs and MWCNTs existed as micron-sized aggregates. The trend in the surface area of nanostructures obtained by Brunauer-Emmett-Teller (BET) surface area analysis was SWCNTs>MWCNTs>WSNTs. The BET surface area analysis, TEM analysis and sol fraction analysis results taken together suggest that chemical composition (inorganic vs. carbon nanomaterials), the presence of functional groups (such as sulfide and oxysulfide) and individual dispersion of the nanomaterials in the polymer matrix (absence of aggregation of the reinforcing agent) are the key parameters


    王元战; 唐照评; 郑斌


    Based on the Coulomb' s theory that the earth pressure against the back of a retaining wall is due to the thrust exerted by the sliding wedge of soil from the back of the wall to a plane which passes through the bottom edge of the wall and has an inclination equal to the angle of θ, the theoretical answers to the unit earth pressure, the resultant earth pressure and the point of application of the resultant earth pressure on a retaining wall were obtained for the wall movement mode of rotation about top. The comparisons were made among the formula presented here, the formula for the wall movement mode of translation,the Coulomb' s formula and some experimental observations. It is demonstrated that the magnitudes of the resultant earth pressures for the wall movement mode of rotation about top is equal to that determined by the formula for the wall movement mode of translation and the Coulomb' s theory. But the distribution of the earth pressure and the points of application of the resultant earth pressures have significant difference.

  2. Evolutionary computation for reinforcement learning

    S. Whiteson


    Algorithms for evolutionary computation, which simulate the process of natural selection to solve optimization problems, are an effective tool for discovering high-performing reinforcement-learning policies. Because they can automatically find good representations, handle continuous action spaces, a

  3. Abdominal wall fat pad biopsy

    Amyloidosis - abdominal wall fat pad biopsy; Abdominal wall biopsy; Biopsy - abdominal wall fat pad ... method of taking an abdominal wall fat pad biopsy . The health care provider cleans the skin on ...

  4. Optimization of reinforced concrete slabs

    Ferritto, J. M.


    Reinforced concrete cells composed of concrete slabs and used to limit the effects of accidental explosions during hazardous explosives operations are analyzed. An automated design procedure which considers the dynamic nonlinear behavior of the reinforced concrete of arbitrary geometrical and structural configuration subjected to dynamic pressure loading is discussed. The optimum design of the slab is examined using an interior penalty function. The optimization procedure is presented and the results are discussed and compared with finite element analysis.

  5. Deep Reinforcement Learning: An Overview

    Li, Yuxi


    We give an overview of recent exciting achievements of deep reinforcement learning (RL). We start with background of deep learning and reinforcement learning, as well as introduction of testbeds. Next we discuss Deep Q-Network (DQN) and its extensions, asynchronous methods, policy optimization, reward, and planning. After that, we talk about attention and memory, unsupervised learning, and learning to learn. Then we discuss various applications of RL, including games, in particular, AlphaGo, ...

  6. Optimization of reinforced concrete slabs

    Ferritto, J. M.


    Reinforced concrete cells composed of concrete slabs and used to limit the effects of accidental explosions during hazardous explosives operations are analyzed. An automated design procedure which considers the dynamic nonlinear behavior of the reinforced concrete of arbitrary geometrical and structural configuration subjected to dynamic pressure loading is discussed. The optimum design of the slab is examined using an interior penalty function. The optimization procedure is presented and the results are discussed and compared with finite element analysis.

  7. Reinforcement of concrete structures by fiberglass rods

    Avdeeva Arina


    Full Text Available In this article we introduced conducted experiments to determine the basic characteristics of composite reinforcement fiberglass reinforcement on the example of the same diameter, but with a different number of rovings. We have established strength along the reinforcing fiber and the corresponding class of the steel reinforcement.

  8. Carbon Nanotubes Reinforced Composites for Biomedical Applications

    Wei Wang


    Full Text Available This review paper reported carbon nanotubes reinforced composites for biomedical applications. Several studies have found enhancement in the mechanical properties of CNTs-based reinforced composites by the addition of CNTs. CNTs reinforced composites have been intensively investigated for many aspects of life, especially being made for biomedical applications. The review introduced fabrication of CNTs reinforced composites (CNTs reinforced metal matrix composites, CNTs reinforced polymer matrix composites, and CNTs reinforced ceramic matrix composites, their mechanical properties, cell experiments in vitro, and biocompatibility tests in vivo.

  9. Carbon nanotubes reinforced composites for biomedical applications.

    Wang, Wei; Zhu, Yuhe; Liao, Susan; Li, Jiajia


    This review paper reported carbon nanotubes reinforced composites for biomedical applications. Several studies have found enhancement in the mechanical properties of CNTs-based reinforced composites by the addition of CNTs. CNTs reinforced composites have been intensively investigated for many aspects of life, especially being made for biomedical applications. The review introduced fabrication of CNTs reinforced composites (CNTs reinforced metal matrix composites, CNTs reinforced polymer matrix composites, and CNTs reinforced ceramic matrix composites), their mechanical properties, cell experiments in vitro, and biocompatibility tests in vivo.

  10. Methods for producing reinforced carbon nanotubes

    Ren, Zhifen; Wen, Jian Guo; Lao, Jing Y.; Li, Wenzhi


    Methods for producing reinforced carbon nanotubes having a plurality of microparticulate carbide or oxide materials formed substantially on the surface of such reinforced carbon nanotubes composite materials are disclosed. In particular, the present invention provides reinforced carbon nanotubes (CNTs) having a plurality of boron carbide nanolumps formed substantially on a surface of the reinforced CNTs that provide a reinforcing effect on CNTs, enabling their use as effective reinforcing fillers for matrix materials to give high-strength composites. The present invention also provides methods for producing such carbide reinforced CNTs.

  11. Liquid Wall Chambers

    Meier, W R


    The key feature of liquid wall chambers is the use of a renewable liquid layer to protect chamber structures from target emissions. Two primary options have been proposed and studied: wetted wall chambers and thick liquid wall (TLW) chambers. With wetted wall designs, a thin layer of liquid shields the structural first wall from short ranged target emissions (x-rays, ions and debris) but not neutrons. Various schemes have been proposed to establish and renew the liquid layer between shots including flow-guiding porous fabrics (e.g., Osiris, HIBALL), porous rigid structures (Prometheus) and thin film flows (KOYO). The thin liquid layer can be the tritium breeding material (e.g., flibe, PbLi, or Li) or another liquid metal such as Pb. TLWs use liquid jets injected by stationary or oscillating nozzles to form a neutronically thick layer (typically with an effective thickness of {approx}50 cm) of liquid between the target and first structural wall. In addition to absorbing short ranged emissions, the thick liquid layer degrades the neutron flux and energy reaching the first wall, typically by {approx}10 x x, so that steel walls can survive for the life of the plant ({approx}30-60 yrs). The thick liquid serves as the primary coolant and tritium breeding material (most recent designs use flibe, but the earliest concepts used Li). In essence, the TLW places the fusion blanket inside the first wall instead of behind the first wall.

  12. Role of Instructions and Reinforcement in Behavior Changes in Token Reinforcement Programs

    Kazdin, Alan E.


    Major findings were that: contingent reinforcement was effective in altering behavior; instructions did not augment the efficacy of contingent reinforcement; noncontingent reinforcement was effective for nondeviant students who were told that the reinforcement was actually contingent; and contingent reinforcement led to greater generalization than…

  13. A Wall of Funnels Concentrates Swimming Bacteria▿

    Galajda, Peter; Keymer, Juan; Chaikin, Paul; Austin, Robert


    Randomly moving but self-propelled agents, such as Escherichia coli bacteria, are expected to fill a volume homogeneously. However, we show that when a population of bacteria is exposed to a microfabricated wall of funnel-shaped openings, the random motion of bacteria through the openings is rectified by tracking (trapping) of the swimming bacteria along the funnel wall. This leads to a buildup of the concentration of swimming cells on the narrow opening side of the funnel wall but no concentration of nonswimming cells. Similarly, we show that a series of such funnel walls functions as a multistage pump and can increase the concentration of motile bacteria exponentially with the number of walls. The funnel wall can be arranged along arbitrary shapes and cause the bacteria to form well-defined patterns. The funnel effect may also have implications on the transport and distribution of motile microorganisms in irregular confined environments, such as porous media, wet soil, or biological tissue, or act as a selection pressure in evolution experiments. PMID:17890308

  14. Reinforcement Learning Algorithms in Humanoid Robotics

    Katic, Dusko; Vukobratovic, Miomir


    This study considers a optimal solutions for application of reinforcement learning in humanoid robotics Humanoid Robotics is a very challenging domain for reinforcement learning, Reinforcement learning control algorithms represents general framework to take traditional robotics towards true autonomy and versatility. The reinforcement learning paradigm described above has been successfully implemented for some special type of humanoid robots in the last 10 years. Reinforcement learning is well...

  15. Superimposition of response-independent reinforcement

    Burgess, I. S.; Wearden, J H


    Studies that have superimposed response-independent reinforcement (or reinforcers scheduled by contingencies placed on the absence of responding) upon conventional response-dependent schedules are reviewed. In general, providing alternative sources of reinforcement reduced response rates below the levels observed when alternative reinforcement was absent. However, response-rate elevation was sometimes found, particularly when rates of superimposed response-independent reinforcement were low. ...

  16. Cell Wall Heterogeneity in Root Development of Arabidopsis

    Somssich, Marc; Khan, Ghazanfar Abbas; Persson, Staffan


    Plant cell walls provide stability and protection to plant cells. During growth and development the composition of cell walls changes, but provides enough strength to withstand the turgor of the cells. Hence, cell walls are highly flexible and diverse in nature. These characteristics are important during root growth, as plant roots consist of radial patterns of cells that have diverse functions and that are at different developmental stages along the growth axis. Young stem cell daughters undergo a series of rapid cell divisions, during which new cell walls are formed that are highly dynamic, and that support rapid anisotropic cell expansion. Once the cells have differentiated, the walls of specific cell types need to comply with and support different cell functions. For example, a newly formed root hair needs to be able to break through the surrounding soil, while endodermal cells modify their walls at distinct positions to form Casparian strips between them. Hence, the cell walls are modified and rebuilt while cells transit through different developmental stages. In addition, the cell walls of roots readjust to their environment to support growth and to maximize nutrient uptake. Many of these modifications are likely driven by different developmental and stress signaling pathways. However, our understanding of how such pathways affect cell wall modifications and what enzymes are involved remain largely unknown. In this review we aim to compile data linking cell wall content and re-modeling to developmental stages of root cells, and dissect how root cell walls respond to certain environmental changes. PMID:27582757

  17. Further weight reduction of applications in long glass reinforced polymers

    Yanev, A.; Schijve, W.; Martin, C.; Brands, D.


    Long glass reinforced materials are broadly used in the automotive industry due to their good mechanical performance, competitive price and options for functional integration in order to reduce weight. With rapidly changing environmental requirements, a demand for further weight reduction is growing constantly. Designs in LGF-PP can bring light weight solutions in combination with system cost improvement. There are quite some possibilities for applying weight reduction technologies nowadays. These technologies have to be evaluated based on weight reduction potential, but also on mechanical performance of the end application, where the latter is often the key to success. Different weight reduction technologies are applied to SABIC®STAMAX{trade mark, serif} material, a long glass fiber reinforced polypropylene (LGF-PP), in order to investigate and define best application performance. These techniques include: chemical foaming, physical foaming and thin wall applications. Results from this research will be presented, giving a guideline for your development.

  18. Steel fiber reinforced concrete behavior, modelling and design

    Singh, Harvinder


    This book discusses design aspects of steel fiber-reinforced concrete (SFRC) members, including the behavior of the SFRC and its modeling. It also examines the effect of various parameters governing the response of SFRC members in detail. Unlike other publications available in the form of guidelines, which mainly describe design methods based on experimental results, it describes the basic concepts and principles of designing structural members using SFRC as a structural material, predominantly subjected to flexure and shear. Although applications to special structures, such as bridges, retaining walls, tanks and silos are not specifically covered, the fundamental design concepts remain the same and can easily be extended to these elements. It introduces the principles and related theories for predicting the role of steel fibers in reinforcing concrete members concisely and logically, and presents various material models to predict the response of SFRC members in detail. These are then gradually extended to d...

  19. Mechanical Reinforcement of Diopside Bone Scaffolds with Carbon Nanotubes

    Cijun Shuai


    Full Text Available Carbon nanotubes are ideal candidates for the mechanical reinforcement of ceramic due to their excellent mechanical properties, high aspect ratio and nanometer scale diameter. In this study, the effects of multi-walled carbon nanotubes (MWCNTs on the mechanical properties of diopside (Di scaffolds fabricated by selective laser sintering were investigated. Results showed that compressive strength and fracture toughness improved significantly with increasing MWCNTs from 0.5 to 2 wt %, and then declined with increasing MWCNTs to 5 wt %. Compressive strength and fracture toughness were enhanced by 106% and 21%, respectively. The reinforcing mechanisms were identified as crack deflection, MWCNTs crack bridging and pull-out. Further, the scaffolds exhibited good apatite-formation ability and supported adhesion and proliferation of cells in vitro.




    Full Text Available This study used steel fibre as reinforcement while enhancing the EPS-LWC strength. In line with architectural demand and ventilation requirement, opening within wall panel was also taken into account. Experimental tests were conducted for reinforced and unreinforced EPS-LWC wall panel. Two samples with size of 1500 mm (height x 1000 mm (length x 75 mm (thickness for each group of wall panel were prepared. Samples in each group had opening size of 600 mm (height x 400 mm (length located at 350 mm and 550 mm from upper end respectively. EPS-LWC wall panel had fcu of 20.87 N/mm2 and a density of 1900 kg/m3. The loading capacity, displacement profiles and crack pattern of each sample was analyzed and discussed. Unreinforced EPS-LWC enhanced with steel fibre resist almost similar loading as reinforced EPS-LWC wall panel. The presence of steel fibre as the only reinforcement creates higher lateral displacement. Wall panel experience shear failure at the side of opening. The number of micro cracks reduces significantly due to presence of steel fibre.

  1. Plastic Deformation of Copper-Based Alloy Reinforced with Incoherent Nanoparticles

    Matvienko, O. V.; Daneiko, O. I.; Kovalevskaya, T. A.


    The paper deals with research carried out into plastic deformation of a heavy-wall pipe made of nanoparticle reinforced copper-based alloy. We present an original approach which combines methods of crystal plasticity and deformable solid mechanics, thereby allowing to study the stress-strain state of the heavy-wall pipe strengthened with incoherent nanoparticles using a homogeneous internal pressure. Dependences are constructed for the yielding area and the pressure, the limit of elasto-plastic resistance is obtained for the heavy-wall pipe and its deformation degree is described. It is shown that the particle size has an effect on strength properties of the material.

  2. The dorsal shell wall structure of Mesozoic ammonoids

    Gregor Radtke


    Full Text Available The study of pristine preserved shells of Mesozoic Ammonoidea shows different types of construction and formation of the dorsal shell wall. We observe three major types: (i The vast majority of Ammonoidea, usually planispirally coiled, has a prismatic reduced dorsal shell wall which consists of an outer organic component (e.g., wrinkle layer, which is the first layer to be formed, and the subsequently formed dorsal inner prismatic layer. The dorsal mantle tissue suppresses the formation of the outer prismatic layer and nacreous layer. With the exception of the outer organic component, secretion of a shell wall is omitted at the aperture. A prismatic reduced dorsal shell wall is always secreted immediately after the hatching during early teleoconch formation. Due to its broad distribution in (planispiral Ammonoidea, the prismatic reduced dorsal shell wall is probably the general state. (ii Some planispirally coiled Ammonoidea have a nacreous reduced dorsal shell wall which consists of three mineralized layers: two prismatic layers (primary and secondary dorsal inner prismatic layer and an enclosed nacreous layer (secondary dorsal nacreous layer. The dorsal shell wall is omitted at the aperture and was secreted in the rear living chamber. Its layers are a continuation of an umbilical shell doubling (reinforcement by additional shell layers that extends towards the ventral crest of the preceding whorl. The nacreous reduced dorsal shell wall is formed in the process of ontogeny following a prismatic reduced dorsal shell wall. (iii Heteromorph and some planispirally coiled taxa secrete a complete dorsal shell wall which forms a continuation of the ventral and lateral shell layers. It is formed during ontogeny following a prismatic reduced dorsal shell wall or a priori. The construction is identical with the ventral and lateral shell wall, including a dorsal nacreous layer. The wide distribution of the ability to form dorsal nacre indicates that it is

  3. Solar heating wall

    Schoenfelder, J.L.


    A solar heating wall is disclosed including a water pipe circulation system having a plurality of separate tubes, each formed as a loop, connected between a water supply and a return. The separate tubes are arranged in a single vertical plane at the approximate center of the wall. The wall is formed within a frame which is packed with a material suited for use as a thERMAL RESERVOIR, SUCH AS concrete. The frame provides extra support by having a series of horizontally disposed cross supports on one surface of the wall and a series of vertically disposed cross supports on the opposite surface A pressure relief valve may be provided between the water supply to the separate tubes and the water supply to the building or structure containing the solar wall, so that the solar wall can be adapted for use with a city water system.

  4. Evaluation of seismic shear capacity of prestressed concrete containment vessels with fiber reinforcement

    Choun, Young Sun; Park, Jun Hee [Integrated Safety Assessment Division, Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)


    Fibers have been used in cement mixture to improve its toughness, ductility, and tensile strength, and to enhance the cracking and deformation characteristics of concrete structural members. The addition of fibers into conventional reinforced concrete can enhance the structural and functional performances of safety-related concrete structures in nuclear power plants. The effects of steel and polyamide fibers on the shear resisting capacity of a prestressed concrete containment vessel (PCCV) were investigated in this study. For a comparative evaluation between the shear performances of structural walls constructed with conventional concrete, steel fiber reinforced concrete, and polyamide fiber reinforced concrete, cyclic tests for wall specimens were conducted and hysteretic models were derived. The shear resisting capacity of a PCCV constructed with fiber reinforced concrete can be improved considerably. When steel fiber reinforced concrete contains hooked steel fibers in a volume fraction of 1.0%, the maximum lateral displacement of a PCCV can be improved by > 50%, in comparison with that of a conventional PCCV. When polyamide fiber reinforced concrete contains polyamide fibers in a volume fraction of 1.5%, the maximum lateral displacement of a PCCV can be enhanced by ∼40%. In particular, the energy dissipation capacity in a fiber reinforced PCCV can be enhanced by > 200%. The addition of fibers into conventional concrete increases the ductility and energy dissipation of wall structures significantly. Fibers can be effectively used to improve the structural performance of a PCCV subjected to strong ground motions. Steel fibers are more effective in enhancing the shear performance of a PCCV than polyamide fibers.

  5. Cell Wall Proteome

    Boudart, Georges; Minic, Zoran; Albenne, Cécile; Canut, Hervé; Jamet, Elisabeth; Pont-Lezica, Rafael F


    In this chapter, we will focus on the contribution of proteomics to the identification and determination of the structure and function of CWPs as well as discussing new perspectives in this area. The great variety of proteins found in the plant cell wall is described. Some families, such as glycoside hydrolases, proteases, lectins, and inhibitors of cell wall modifying enzymes, are discussed in detail. Examples of the use of proteomic techniques to elucidate the structure of various cell wall...

  6. Staggered domain wall fermions

    Hoelbling, Christian


    We construct domain wall fermions with a staggered kernel and investigate their spectral and chiral properties numerically in the Schwinger model. In some relevant cases we see an improvement of chirality by more than an order of magnitude as compared to usual domain wall fermions. Moreover, we present first results for four-dimensional quantum chromodynamics, where we also observe significant reductions of chiral symmetry violations for staggered domain wall fermions.

  7. Green walls in Vancouver

    Sharp, R. [Sharp and Diamond Landscape Architecture Inc., Vancouver, BC (Canada)


    With the renewed interest in design for microclimate control and energy conservation, many cities are implementing clean air initiatives and sustainable planning policies to mitigate the effects of urban climate and the urban heat island effect. Green roofs, sky courts and green walls must be thoughtfully designed to withstand severe conditions such as moisture stress, extremes in temperature, tropical storms and strong desiccating winds. This paper focused on the installation of green wall systems. There are 2 general types of green walls systems, namely facade greening and living walls. Green facades are trellis systems where climbing plants can grow vertically without attaching to the surface of the building. Living walls are part of a building envelope system where plants are actually planted and grown in a wall system. A modular G-SKY Green Wall Panel was installed at the Aquaquest Learning Centre at the Vancouver Aquarium in Stanley Park in September 2006. This green wall panel, which was originally developed in Japan, incorporates many innovative features in the building envelope. It provides an exterior wall covered with 8 species of plants native to the Coastal Temperate Rain Forest. The living wall is irrigated by rainwater collected from the roof, stored in an underground cistern and fed through a drip irrigation system. From a habitat perspective, the building imitates an escarpment. Installation, support systems, irrigation, replacement of modules and maintenance are included in the complete wall system. Living walls reduce the surface temperature of buildings by as much as 10 degrees C when covered with vegetation and a growing medium. The project team is anticipating LEED gold certification under the United States-Canada Green Building Council. It was concluded that this technology of vegetated building envelopes is applicable for acoustical control at airports, biofiltration of indoor air, greywater treatment, and urban agriculture and vertical

  8. Seismic Analysis of Reinforced Concrete Shaft Support Water Storage Tank

    Bharti Tekwani


    Full Text Available This paper compares the results of Seismic Analysis of Reinforced Concrete Shaft Support Water Storage Tank carried out in accordance with IS: 1893- 1984 and IS: 1893-2002 (Part-2 draft code. The analysis is carried out for shaft supported water tank of 500,750 and 1000 Cu.m capacity, located in four seismic zones (Zone-II, Zone -III, Zone-IV, Zone-V and on three different soil types (Hard rock, Medium soil, Soft soil. Further, 1000 kl tank for conditions - tank full, tank empty are also considered in this study. The analysis was performed using MAT LAB. The parameters of comparison include base shears, base moments and time history analysis. The above models are analyzed for different time history data such as El Centro, Kobe, Ji-Ji, Erzincan. The comparison is made between the structural responses of one mass and two mass models of above capacity.


    牛琪瑛; 刘峰; 郭英; 刘少文


    该文运用三维有限差分软件FLAC3D(Fast Lagrangian Analysis of Continua)对水泥土桩加固的液化砂土地基建立模型并进行地震响应分析,从计算机数值模拟的角度对水泥土桩加固模型地基竖向位移、超静孔隙水压力、孔压比、剪应变增量、接触面剪力及表面加速度作了较系统地分析,总结了这些参数的变化规律,得到了一些有价值的结论,对实际工程有一定的指导意义.%The three-dimensional finite difference program FLAC3D (Fast Lagrangian Analysis of Continua) is used to establish the model of the improved foundation soil by cement piles and to analyze seismic response.From the point of the numerical analysis,it adopts a visualized way to make a systematic analysis about the vertical displacement,the excess pore water pressure,the pore pressure ratio,the shear strain increment,the shear stress on interface elements and the surface acceleration.It helps us to obtain some valuable conclusions by summarizing the changing patterns of above parameters.It has definite instruct meaning for practical projects in the future.

  10. On the role of CFRP reinforcement for wood beams stiffness

    Ianasi, A. C.


    In recent years, carbon fiber composites have been increasingly used in different ways in reinforcing structural elements. Specifically, the use of composite materials as a reinforcement for wood beams under bending loads requires paying attention to several aspects of the problem such as the number of the composite layers applied on the wood beams. Study consolidation of composites revealed that they are made by bonding fibrous material impregnated with resin on the surface of various elements, to restore or increase the load carrying capacity (bending, cutting, compression or torque) without significant damage of their rigidity. Fibers used in building applications can be fiberglass, aramid or carbon. Items that can be strengthened are concrete, brick, wood, steel and stone, and in terms of structural beams, walls, columns and floors. This paper describes an experimental study which was designed to evaluate the effect of composite material on the stiffness of the wood beams. It proposes a summary of the fundamental principles of analysis of composite materials and the design and use. The type of reinforcement used on the beams is the carbon fiber reinforced polymer (CFRP) sheet and plates and also an epoxy resin for bonding all the elements. Structural epoxy resins remain the primary choice of adhesive to form the bond to fiber-reinforced plastics and are the generally accepted adhesives in bonded CFRP-wood connections. The advantages of using epoxy resin in comparison to common wood-laminating adhesives are their gap-filling qualities and the low clamping pressures that are required to form the bond between carbon fiber plates or sheets and the wood beams. Mechanical tests performed on the reinforced wood beams showed that CFRP materials may produce flexural displacement and lifting increases of the beams. Observations of the experimental load-displacement relationships showed that bending strength increased for wood beams reinforced with CFRP composite plates

  11. The ultimate strength of doubler plate reinforced Y-joints under compression loading

    FENQ Qi; TAN Jia-hua


    It is common practice in the offshore industry to solve the punching shear problem due to compression by using doubler plate. The finite-element method is a useful tool for studying this problem. The aim of this paper is to study the static strength of doubler plate reinforced Y-joints subjected to compression loading. The finite-element method is adopted in numerical parametric studies. The individual influences of the geometric parameters βand τd (doubler plate to chord wall thickness ratio) and ld/d1(dubler plate length to brace diameter ratio) on the ultimate strength are made clear. The results show the size of plate may have important effects on the strength of reinforced joints. It is found that the ultimate strength of Y-joints reinforced with appropriately proportioned doubler plates can be greatly improved nearly up tothree times to un-reinforced Y-joints.

  12. Tissue-engineering with muscle fiber fragments improves the strength of a weak abdominal wall in rats

    Jangö, Hanna; Gräs, Søren; Christensen, Lise


    INTRODUCTION AND HYPOTHESIS: Alternative approaches to reinforce the native tissue in patients with pelvic organ prolapse (POP) are needed to improve surgical outcome. Our aims were to develop a weakened abdominal wall in a rat model to mimic the weakened vaginal wall in women with POP...

  13. An Analysis for Cross Beam-Ground Anchor Reinforcement

    Xu Yingzi; Zhang Baiqing; Tang Huiming


    With the rapid development of water facilities, hydroelectric projects, highways and railways in China, beam-anchor reinforcement has been widely used to stabilize slopes in recent years. But the theory for the design of beam-anchor reinforcement is far behind the application. Cross beam-ground anchor reinforcement is a combination of beams and anchors forming a new structure to prevent slope sliding. The forces in the beams are discussed using theoretical analysis and numerical modeling. The Winkler model is used to analyze the beams, and reasonable values of λ, length, spacing and cantilevered length for the beams are determined through a theoretical analysis. A three-dimensional finite element method is adopted to model the interaction of the beams and soils and a structure analysis is applied to treat the beams and to study the stress distribution in external and internal beams. The analytical results show that it is better to satisfy λ≥2π, the spacing between anchors ls should be lsλ<π/2 and cantilever length should be (0.3-0.5)ls for the optimum design. The numerical results show that the same design can be used for all beams in different directions, including the internal and external beams. The application of the analytical method for reinforcement beam analysis is acceptable. It is better to choose a safety coefficient of 1.3 for design based on the analytical method for safety.

  14. Reinforcement learning and Tourette syndrome.

    Palminteri, Stefano; Pessiglione, Mathias


    In this chapter, we report the first experimental explorations of reinforcement learning in Tourette syndrome, realized by our team in the last few years. This report will be preceded by an introduction aimed to provide the reader with the state of the art of the knowledge concerning the neural bases of reinforcement learning at the moment of these studies and the scientific rationale beyond them. In short, reinforcement learning is learning by trial and error to maximize rewards and minimize punishments. This decision-making and learning process implicates the dopaminergic system projecting to the frontal cortex-basal ganglia circuits. A large body of evidence suggests that the dysfunction of the same neural systems is implicated in the pathophysiology of Tourette syndrome. Our results show that Tourette condition, as well as the most common pharmacological treatments (dopamine antagonists), affects reinforcement learning performance in these patients. Specifically, the results suggest a deficit in negative reinforcement learning, possibly underpinned by a functional hyperdopaminergia, which could explain the persistence of tics, despite their evident inadaptive (negative) value. This idea, together with the implications of these results in Tourette therapy and the future perspectives, is discussed in Section 4 of this chapter.

  15. Load carrying capacity of keyed joints reinforced with high strength wire rope loops

    Jørgensen, Henrik B.; Hoang, Linh Cao


    Vertical shear connections between precast concrete wall elements are usually made as keyed joints reinforced with overlapping U-bars. The overlapping U-bars form a cylindrical core in which the locking bar is placed and the connection is subsequently grouted with mortar. A more construction...... friendly shear connection can be obtained by replacing the U-bars with high strength looped wire ropes. The wire ropes have the advantage of being flexible (they have virtually no bending stiffness) which makes installation of wall elements much easier. The looped wire ropes are usually pre-installed in so......-called wire boxes which are embedded in the precast wall elements. Once the joint is grouted with mortar, the boxes will function as shear keys and the overlapping wire loops will function as transverse reinforcement that replaces the U-bars. This paper presents a rigid-plastic upper bound model to determine...

  16. Load Carrying Capacity of Keyed Joints Reinforced with High Strength Wire Rope Loops

    Jørgensen, Henrik Brøner; Hoang, Linh Cao

    Vertical shear connections between precast concrete wall elements are usually made as keyed joints reinforced with overlapping U-bars. The overlapping U-bars form a cylindrical core in which the locking bar is placed and the connection is subsequently grouted with mortar. A more construction...... friendly shear connection can be obtained by replacing the U-bars with high strength looped wire ropes. The wire ropes have the advantage of being flexible (they have virtually no bending stiffness) which makes installation of wall elements much easier. The looped wire ropes are usually pre-installed in so......-called wire boxes which are embedded in the precast wall elements. Once the joint is grouted with mortar, the boxes will function as shear keys and the overlapping wire loops will function as transverse reinforcement that replaces the U-bars. This paper presents a rigid-plastic upper bound model to determine...

  17. Carbon nanotube reinforced polyacrylonitrile and poly(etherketone) fibers

    Jain, Rahul

    The graphitic nature, continuous structure, and high mechanical properties of carbon nanotubes (CNTs) make them good candidate for reinforcing polymer fiber. The different types of CNTs including single-wall carbon nanotubes (SWNTs), few-wall carbon nanotubes (FWNTs), and multi-wall carbon nanotubes (MWNTs), and carbon nanofibers (CNFs) differ in terms of their diameter and number of graphitic walls. The desire has been to increase the concentration of CNTs as much as possible to make next generation multi-functional materials. The work in this thesis is mainly focused on MWNT and CNF reinforced polyacrylonitrile (PAN) composite fibers, and SWNT, FWNT, and MWNT reinforced poly(etherketone) (PEK) composite fibers. To the best of our knowledge, this is the first study to report the spinning of 20% MWNT or 30% CNF reinforced polymer fiber spun using conventional fiber spinning. Also, this is the first study to report the PEK/CNT composite fibers. The fibers were characterized for their thermal, tensile, mechanical, and dynamic mechanical properties. The fiber structure and morphology was studied using WAXD and SEM. The effect of two-stage heat drawing, sonication time for CNF dispersion, fiber drying temperature, and molecular weight of PAN was also studied. Other challenges associated with processing high concentrations of solutions for making composite fibers have been identified and reported. The effect of CNT diameter and concentration on fiber spinnability and electrical conductivity of composite fiber have also been studied. This work suggests that CNT diameter controls the maximum possible concentration of CNTs in a composite fiber. The results show that by properly choosing the type of CNT, length of CNTs, dispersion of CNTs, fiber spinning method, fiber draw ratio, and type of polymer, one can get electrically conducting fibers with wide range of conductivities for different applications. The PEK based control and composite fibers possess high thermal

  18. Carbon-Nanotube-Reinforced Polymer-Derived Ceramic Composites

    An, Linan; Xu, Weixing; Rajagopalan, Sudhir; Wang, Chong M.; Wang, Hsin; Fan, Yi; Zhang, Ligong; Jiang, Dapeng; Kapat, Jay; Chow, Louis; Guo, Baohua; Liang, Ji; Vaidyanathan, Raj


    Carbon nanotube reinforced ceramic composites were synthesized by using recently developed polymer-derived ceramics as matrices. Multi-wall carbon nanotubes, treated with a surfactant, were first dispersed in a liquid polymer precursor by sonication and mechanical stirring. The solution was then converted to fully dense ceramic composites with pressure-assist pyrolysis technique. Microstructural observation revealed that nanotubes were homogeneously dispersed throughout the ceramic matrix. Significant increases in mechanical and thermal properties were observed by adding only {approx}6vol% nanotubes. Strong nanotube pullout revealed by SEM observation suggested that the composites could possess high fracture toughness.

  19. Quicklime-induced changes of soil properties: Implications for enhanced remediation of volatile chlorinated hydrocarbon contaminated soils via mechanical soil aeration.

    Ma, Yan; Dong, Binbin; He, Xiaosong; Shi, Yi; Xu, Mingyue; He, Xuwen; Du, Xiaoming; Li, Fasheng


    Mechanical soil aeration is used for soil remediation at sites contaminated by volatile organic compounds. However, the effectiveness of the method is limited by low soil temperature, high soil moisture, and high soil viscosity. Combined with mechanical soil aeration, quicklime has a practical application value related to reinforcement remediation and to its action in the remediation of soil contaminated with volatile organic compounds. In this study, the target pollutant was trichloroethylene, which is a volatile chlorinated hydrocarbon pollutant commonly found in contaminated soils. A restoration experiment was carried out, using a set of mechanical soil-aeration simulation tests, by adding quicklime (mass ratios of 3, 10, and 20%) to the contaminated soil. The results clearly indicate that quicklime changed the physical properties of the soil, which affected the environmental behaviour of trichloroethylene in the soil. The addition of CaO increased soil temperature and reduced soil moisture to improve the mass transfer of trichloroethylene. In addition, it improved the macroporous cumulative pore volume and average pore size, which increased soil permeability. As soil pH increased, the clay mineral content in the soils decreased, the cation exchange capacity and the redox potential decreased, and the removal of trichloroethylene from the soil was enhanced to a certain extent. After the addition of quicklime, the functional group COO of soil organic matter could interact with calcium ions, which increased soil polarity and promoted the removal of trichloroethylene. Copyright © 2017 Elsevier Ltd. All rights reserved.

  20. Synthetic, biological and composite scaffolds for abdominal wall reconstruction.

    Meintjes, Jennifer; Yan, Sheng; Zhou, Lin; Zheng, Shusen; Zheng, Minghao


    The reconstruction of abdominal wall defects remains a huge surgical challenge. Tension-free repair is proven to be superior to suture repair in abdominal wall reconstruction. Scaffolds are essential for tension-free repair. They are used to bridge a defect or reinforce the abdominal wall. A huge variety of scaffolds are now commercially available. Most of the synthetic scaffolds are composed of polypropylene. They provide strong tissue reinforcement, but cause a foreign body reaction, which can result in serious complications. Absorbable synthetic scaffolds, such as Dexon™ (polyglycolic acid) and Vicryl™ (polyglactin 910), are not suitable for abdominal wall reconstruction as they usually require subsequent surgeries to repair recurrent hernias. Composite scaffolds combine the strength of nonabsorbable synthetic scaffolds with the antiadhesive properties of the absorbable scaffold, but require long-term follow-up. Biological scaffolds, such as Permacol™, Surgisis(®) and Alloderm(®), are derived from acellular mammalian tissues. Non-cross-linked biological scaffolds show excellent biocompatibility and degrade slowly over time. However, remnant DNA has been found in several products and the degradation leads to recurrence. Randomized controlled trials with long-term follow-up studies are lacking for all of the available scaffolds, particularly those derived from animal tissue. This article provides an overview of the different types of scaffolds available, and presents the key clinical studies of the commercially available synthetic, composite and biological scaffolds for abdominal wall reconstruction.

  1. Does supplementary reinforcement of stereotypy facilitate extinction?

    Dozier, Claudia L; Iwata, Brian A; Wilson, David M; Thomason-Sassi, Jessica L; Roscoe, Eileen M


    Results of several studies suggest that delivery of supplemental (social) reinforcement for stereotypy might facilitate its subsequent extinction. We examined this possibility with 9 subjects who engaged in stereotypy by including methodological refinements to ensure that (a) subjects' stereotypy was maintained in the absence of social consequences, (b) supplementary reinforcers were highly preferred and were shown to be reinforcers for some behavior, and (c) subjects were exposed to lengthy reinforcement and extinction conditions. In spite of these modifications, only 4 subjects' stereotypy increased when supplementary reinforcement was delivered contingent on stereotypy, and no subject's stereotypy decreased below initial baseline levels when social reinforcement was subsequently withheld. Decreases in stereotypy occurred with the implementation of noncontingent reinforcement. Thus, delivery of supplementary reinforcers either did not increase stereotypy or did not facilitate extinction of stereotypy maintained by automatic reinforcement. We discuss the practical and conceptual bases of these results with respect to our current understanding of function-based interventions.

  2. Design of SC walls and slabs for impulsive loading

    Varma, Amit H. [Purdue Univ., West Lafayette, IN (United States)


    Reinforced concrete (RC) structures have historically been the preferred choice for blast resistant structures because of their mass and the ductility provided by steel reinforcement. Steel-plate composite (SC) walls are a viable alternative to RC for protecting the infrastructure against explosive threats. SC structures consist of two steel faceplates with a plain concrete core between them. The steel faceplates are anchored to the concrete using stud anchors and connected to each other using tie bars. SC structures provide mass from the concrete infill and ductility from the continuous external steel faceplates. This dissertation presents findings and recommendations from experimental and analytical investigations of the performance of SC walls subjected to far-field blast loads.

  3. Stress Ratio-Strain Relation of Pile and Soil in Composite Foundation

    LIU Fei; GAO Quan-chen; JING Lai-wang; ZHAO Yan-lin


    A series of triaxial compression tests were arried out by means of composite-reinforced soil samples to simulate the interaction between soil and pile. The samples are made of gravel or lime-soil with different length at the center. The experiment indicates that the strength of the composite samples can not be obtained by superimposure of reinforcing pile and soil simply according to their replacement proportion. It also indicates the law for stress ratio of reinforcing column to soil. The stress ratio of reinforcing column to soil increases and reaches peak rapidly while load and strain is small. Then the ratio decreases. This law is in accordance with the measuring resuits in construction site.

  4. Assessment of the Mechanical Properties of Sisal Fiber-Reinforced Silty Clay Using Triaxial Shear Tests

    Yankai Wu


    Full Text Available Fiber reinforcement is widely used in construction engineering to improve the mechanical properties of soil because it increases the soil’s strength and improves the soil’s mechanical properties. However, the mechanical properties of fiber-reinforced soils remain controversial. The present study investigated the mechanical properties of silty clay reinforced with discrete, randomly distributed sisal fibers using triaxial shear tests. The sisal fibers were cut to different lengths, randomly mixed with silty clay in varying percentages, and compacted to the maximum dry density at the optimum moisture content. The results indicate that with a fiber length of 10 mm and content of 1.0%, sisal fiber-reinforced silty clay is 20% stronger than nonreinforced silty clay. The fiber-reinforced silty clay exhibited crack fracture and surface shear fracture failure modes, implying that sisal fiber is a good earth reinforcement material with potential applications in civil engineering, dam foundation, roadbed engineering, and ground treatment.

  5. Analysing hydro-mechanical behaviour of reinforced slopes through centrifuge modelling

    Veenhof, Rick; Wu, Wei


    Every year, slope instability is causing casualties and damage to properties and the environment. The behaviour of slopes during and after these kind of events is complex and depends on meteorological conditions, slope geometry, hydro-mechanical soil properties, boundary conditions and the initial state of the soils. This study describes the effects of adding reinforcement, consisting of randomly distributed polyolefin monofilament fibres or Ryegrass (Lolium), on the behaviour of medium-fine sand in loose and medium dense conditions. Direct shear tests were performed on sand specimens with different void ratios, water content and fibre or root density, respectively. To simulate the stress state of real scale field situations, centrifuge model tests were conducted on sand specimens with different slope angles, thickness of the reinforced layer, fibre density, void ratio and water content. An increase in peak shear strength is observed in all reinforced cases. Centrifuge tests show that for slopes that are reinforced the period until failure is extended. The location of shear band formation and patch displacement behaviour indicate that the design of slope reinforcement has a significant effect on the failure behaviour. Future research will focus on the effect of plant water uptake on soil cohesion.

  6. International Divider Walls

    Kruis, A.; Sneller, A.C.W.(L.)


    The subject of this teaching case is the Enterprise Resource Planning (ERP) system implementation at International Divider Walls, the world market leader in design, production, and sales of divider walls. The implementation in one of the divisions of this multinational company had been successful, a

  7. Domain wall filters

    Bär, O; Neuberger, H; Witzel, O; Baer, Oliver; Narayanan, Rajamani; Neuberger, Herbert; Witzel, Oliver


    We propose using the extra dimension separating the domain walls carrying lattice quarks of opposite handedness to gradually filter out the ultraviolet fluctuations of the gauge fields that are felt by the fermionic excitations living in the bulk. This generalization of the homogeneous domain wall construction has some theoretical features that seem nontrivial.

  8. Thin Wall Iron Castings

    J.F. Cuttino; D.M. Stefanescu; T.S. Piwonka


    Results of an investigation made to develop methods of making iron castings having wall thicknesses as small as 2.5 mm in green sand molds are presented. It was found that thin wall ductile and compacted graphite iron castings can be made and have properties consistent with heavier castings. Green sand molding variables that affect casting dimensions were also identified.

  9. International Divider Walls

    Kruis, A.; Sneller, A.C.W.(L.)


    The subject of this teaching case is the Enterprise Resource Planning (ERP) system implementation at International Divider Walls, the world market leader in design, production, and sales of divider walls. The implementation in one of the divisions of this multinational company had been successful,

  10. Quenched Reinforcement Exposed to Fire

    Hertz, Kristian Dahl


    Idealized data are derived for the tensile strength of quenched and tempered prestressing steel and of quenched and self-tempered reinforcing bars for fire safety design. 0.2% stresses are derived as a function of the maximum temperature and in addition, 2.0% stresses are provided. A strain of 2.......0% is seldom found in “slack” (not prestressed) reinforcement, but 2.0% stresses might be relevant for reinforcement in T shaped cross sections and for prestressed structures, where large strains can be applied. All data are provided in a “HOT” condition during a fire and in a “COLD” condition after a fire....... The COLD condition is relevant for analyses of residual load bearing capacity of a structure after a fire exposure. It is also relevant for analyses of concrete structures exposed to fully developed fire courses. The reason is that compression zones of concrete are always the weakest in the cooling phase...

  11. Localization of reinforced random walks

    Tarrès, Pierre


    We describe and analyze how reinforced random walks can eventually localize, i.e. only visit finitely many sites. After introducing vertex and edge self-interacting walks on a discrete graph in a general setting, and stating the main results and conjectures so far on the topic, we present martingale techniques that provide an alternative proof of the a.s. localization of vertex-reinforced random walks (VRRWs) on the integers on finitely many sites and, with positive probability, on five consecutive sites, initially proved by Pemantle and Volkov (1999). Next we introduce the continuous time-lines representation (sometimes called Rubin construction) and its martingale counterpart, and explain how it has been used to prove localization of some reinforced walks on one attracting edge. Then we show how a modified version of this construction enables one to propose a new short proof of the a.s. localization of VRRWs on five sites on Z.

  12. The power reinforcement framework revisited

    Nielsen, Jeppe; Andersen, Kim Normann; Danziger, James N.


    Whereas digital technologies are often depicted as being capable of disrupting long-standing power structures and facilitating new governance mechanisms, the power reinforcement framework suggests that information and communications technologies tend to strengthen existing power arrangements within...... public organizations. This article revisits the 30-yearold power reinforcement framework by means of an empirical analysis on the use of mobile technology in a large-scale programme in Danish public sector home care. It explores whether and to what extent administrative management has controlled decision......-dominated and centrally controlled technologies that were the main focus of the 1970s and 1980s studies. Yet this study concludes that there is general support for the reinforcement framework in the contemporary application of mobile technology in public sector home care....

  13. Quenched Reinforcement Exposed to Fire

    Hertz, Kristian Dahl


    Idealized data are derived for the tensile strength of quenched and tempered prestressing steel and of quenched and self-tempered reinforcing bars for fire safety design. 0.2% stresses are derived as a function of the maximum temperature and in addition, 2.0% stresses are provided. A strain of 2.......0% is seldom found in “slack” (not prestressed) reinforcement, but 2.0% stresses might be relevant for reinforcement in T shaped cross sections and for prestressed structures, where large strains can be applied. All data are provided in a “HOT” condition during a fire and in a “COLD” condition after a fire....... The COLD condition is relevant for analyses of residual load bearing capacity of a structure after a fire exposure. It is also relevant for analyses of concrete structures exposed to fully developed fire courses. The reason is that compression zones of concrete are always the weakest in the cooling phase...

  14. Plastic Response of Tracheids in Pinus pinaster in a Water-Limited Environment: Adjusting Lumen Size instead of Wall Thickness

    Carvalho, Ana; Nabais, Cristina; Vieira, Joana; Rossi, Sergio; Campelo, Filipe


    The formation of wood results from cambial activity and its anatomical properties reflect the variability of environmental conditions during the growing season. Recently, it was found that wood density variations in conifers growing under cold-limited environment result from the adjustment of cell wall thickness (CWT) to temperature. Additionally, it is known that intra-annual density fluctuations (IADFs) are formed in response to precipitation after the summer drought. Although IADFs are frequent in Mediterranean conifers no study has yet been conducted to determine if these structures result from the adjustment of lumen diameter (LD) or CWT to soil water availability. Our main objective is to investigate the intra-ring variation of wood anatomical features (LD and CWT) in Pinus pinaster Ait. growing under a water-limited environment. We compared the tracheidograms of LD and CWT for the years 2010–2013 in P. pinaster growing in the west coast of Portugal. Our results suggest a close association between LD and soil moisture content along the growing season, reinforcing the role of water availability in determining tracheid size. Compared with CWT, LD showed a higher intra- and inter-annual variability suggesting its strong adjustment value to variations in water availability. The formation of a latewood IADF appears to be predisposed by higher rates of cell production in spring and triggered by early autumn precipitation. Our findings reinforce the crucial role of water availability on cambial activity and wood formation in Mediterranean conifers, and emphasize the high plasticity of wood anatomical features under Mediterranean climate. PMID:26305893

  15. Plastic Response of Tracheids in Pinus pinaster in a Water-Limited Environment: Adjusting Lumen Size instead of Wall Thickness.

    Carvalho, Ana; Nabais, Cristina; Vieira, Joana; Rossi, Sergio; Campelo, Filipe


    The formation of wood results from cambial activity and its anatomical properties reflect the variability of environmental conditions during the growing season. Recently, it was found that wood density variations in conifers growing under cold-limited environment result from the adjustment of cell wall thickness (CWT) to temperature. Additionally, it is known that intra-annual density fluctuations (IADFs) are formed in response to precipitation after the summer drought. Although IADFs are frequent in Mediterranean conifers no study has yet been conducted to determine if these structures result from the adjustment of lumen diameter (LD) or CWT to soil water availability. Our main objective is to investigate the intra-ring variation of wood anatomical features (LD and CWT) in Pinus pinaster Ait. growing under a water-limited environment. We compared the tracheidograms of LD and CWT for the years 2010-2013 in P. pinaster growing in the west coast of Portugal. Our results suggest a close association between LD and soil moisture content along the growing season, reinforcing the role of water availability in determining tracheid size. Compared with CWT, LD showed a higher intra- and inter-annual variability suggesting its strong adjustment value to variations in water availability. The formation of a latewood IADF appears to be predisposed by higher rates of cell production in spring and triggered by early autumn precipitation. Our findings reinforce the crucial role of water availability on cambial activity and wood formation in Mediterranean conifers, and emphasize the high plasticity of wood anatomical features under Mediterranean climate.

  16. Hard and soft walls

    Milton, Kimball A


    In a continuing effort to understand divergences which occur when quantum fields are confined by bounding surfaces, we investigate local energy densities (and the local energy-momentum tensor) in the vicinity of a wall. In this paper, attention is largely confined to a scalar field. If the wall is an infinite Dirichlet plane, well known volume and surface divergences are found, which are regulated by a temporal point-splitting parameter. If the wall is represented by a linear potential in one coordinate $z$, the divergences are softened. The case of a general wall, described by a potential of the form $z^\\alpha$ for $z>0$ is considered. If $\\alpha>2$, there are no surface divergences, which in any case vanish if the conformal stress tensor is employed. Divergences within the wall are also considered.




    Artificially ground freezing (AGF) is one of the main methods to establish temporary support for shaft sinking in unstable water bearing strata. Domke(1915) formula based on frozen soil strength has widely been used for designing freeze wall thickness. However, it can not ensure the stability of freeze wall, nor guarantee the safety of shaft construction as frozen depth increase in unstable water bearing strata. F.A.Auld (1985, 1988) presented a design method of freeze wall, which is on the basis of strength and stability, together with deformation of freeze wall.He combined deformation of freeze wall, lining and deformation of freeze tube to set up a comprehensive design method for freeze wall. This paper, according to the practice in China, describes a comprehensive design method for deep freeze wall, considering influence of excavation rate of advance, unsupported length of freeze wall and the sump state on inward deformation of freeze wall, and the allowable pipe deformation caused by inward deformation of freeze wall. Finally, successful application of this method to the large scale coal mine-Jining No.2 Mine in Shandong Province of China, is presented.It saved much investment compared with F.A.Auld's design for the same mine on behalf of Shell Coal International.

  18. Train induced vibrations in geosynthetic reinforced railway embankments

    Zania, Varvara; Hededal, Ole; Krogsbøll, Anette


    includes usually the application of stabilization techniques like geosynthetic reinforcement. Hence, in the current study the ground vibration, which is induced by a train passage in geosynthetic reinforced embankments, is investigated. In addition the impact of the soil conditions is examined. In order...... to accomplish the aforementioned research goals, dynamic finite element analyses of two-dimensional plane strain models have been performed. The results of the adopted approach, which is rather simplified, were compared with the corresponding results reported in the literature for a real scale experiment....... The quite satisfactory agreement of the results provided an acceptable validation of the numerical procedure. This enabled the parametric investigation for analyzing the effect of the characteristic parameters of the subsoil conditions. The results indicate that the impact of the site conditions...

  19. Mechanical interaction between roots and soil mass in slope vegetation


    The most basic function of slope vegetation is to strengthen rock and soil mass through plant roots which increase the shear strength of the slope markedly and thereby increase the stability of the slope. However, the calculation of the reinforcement ability of slope vegetation still remains at the stage of judging by experience, because it is rather difficult due to the intricacy and volatility of the force condition of plant roots in rock and soil medium. Although some scholars have tried to study the interaction between plant roots and soil mass, the systemic analysis of the mechanical reinforcement mechanism and the contribution of plant roots to strengthening the rock and soil mass on the surface of the slope is untapped. In this paper, by analyzing the mechanism of slope vegetation and the corresponding reinforcement effect, the effects that slope vegetation generates on the shear strength of slope soil mass are studied, thereby a theoretical basis for plant protection designing is provided.

  20. What Happens with Reinforced Concrete Structures when the Reinforcement Corrodes

    Thoft-Christensen, Palle

    In this paper, corrosion of reinforced concrete structures is discussed from the point of view of corrosion products. The different types of corrosion products are presented and a detailed study of the important diffusion coefficient is performed. Stochastic modelling of corrosion initiated...