Introduction to Single Piles under Lateral Loading
DEFF Research Database (Denmark)
Augustesen, Anders; Ibsen, Lars Bo
The purpose of this chapter is to give a short introduction to single piles subjected to lateral loading. First, the observed behaviour of laterally loaded piles is described, i.e. the effects of loading conditions, installation procedure, pile type etc. on pile behaviour are presented (section 1.......2). The description is based on results of laboratory tests, full-scale field tests as well as numerical investigations presented in literature. Second, general methods that attempt to model lateral pile response are discussed in section 1.4. Third, focus is paid to a widely used method for prediction of the response...... of a lateral loaded pile, namely the Winkler approach in which the pile is modelled as an elastic beam on an elastic foundation (section 1.5). The soil response and thereby the elastic foundation is represented by springs with nonlinear behaviour (p-y curves). In section 1.6 different types and formulations...
Pile Load Capacity – Calculation Methods
Directory of Open Access Journals (Sweden)
Wrana Bogumił
2015-12-01
Full Text Available The article is a review of the current problems of the foundation pile capacity calculations. The article considers the main principles of pile capacity calculations presented in Eurocode 7 and other methods with adequate explanations. Two main methods are presented: α – method used to calculate the short-term load capacity of piles in cohesive soils and β – method used to calculate the long-term load capacity of piles in both cohesive and cohesionless soils. Moreover, methods based on cone CPTu result are presented as well as the pile capacity problem based on static tests.
Laterally Loaded Piles in Clay
DEFF Research Database (Denmark)
Christensen, Helle; Niewald, Gitte
1992-01-01
The ultimate lateral resistance of a pile element moved horizontally can be analyzed by the theory of plasticity. At a certain depth the movements around the pile are purely horizontal and upper bound solutions can be estimated theoretically under undrained circumstances. Model tests in the labor...
Laterally Loaded Partially Prestressed Concrete Piles
1989-09-01
of an extensive test program onl laterali y ioadeu. partially pr- estressed concrete fender piles. The study Included service load range as well ats...12,000-psi design strength). Configura- tion G utilized 14 r:- estress strand, in an unsymmetric pattern. To provide a uniform concrete prestress of 540
Twist buckling of veins under torsional loading.
Garcia, Justin R; Sanyal, Arnav; Fatemifar, Fatemeh; Mottahedi, Mohammad; Han, Hai-Chao
2017-06-14
Veins are often subjected to torsion and twisted veins can hinder and disrupt normal blood flow but their mechanical behavior under torsion is poorly understood. The objective of this study was to investigate the twist deformation and buckling behavior of veins under torsion. Twist buckling tests were performed on porcine internal jugular veins (IJVs) and human great saphenous veins (GSVs) at various axial stretch ratio and lumen pressure conditions to determine their critical buckling torques and critical buckling twist angles. The mechanical behavior under torsion was characterized using a two-fiber strain energy density function and the buckling behavior was then simulated using finite element analysis. Our results demonstrated that twist buckling occurred in all veins under excessive torque characterized by a sudden kink formation. The critical buckling torque increased significantly with increasing lumen pressure for both porcine IJV and human GSV. But lumen pressure and axial stretch had little effect on the critical twist angle. The human GSVs are stiffer than the porcine IJVs. Finite element simulations captured the buckling behavior for individual veins under simultaneous extension, inflation, and torsion with strong correlation between predicted critical buckling torques and experimental data (R 2 =0.96). We conclude that veins can buckle under torsion loading and the lumen pressure significantly affects the critical buckling torque. These results improve our understanding of vein twist behavior and help identify key factors associated in the formation of twisted veins. Copyright © 2017 Elsevier Ltd. All rights reserved.
Test Procedure for Axially Loaded Piles in Sand
DEFF Research Database (Denmark)
Thomassen, Kristina
The test procedure described in the following is used when examining the effects of static or cyclic loading on the skin friction of an axially loaded pile in dense sand. The pile specimen is only loaded in tension to avoid any contribution from the base resistance. The pile dimensions are chosen...... to resemble full scale dimension of piles used in offshore pile foundations today. In this report is given a detailed description of the soil preparation and pile installation procedures as well data acquisition methods....
Use of pile driving analysis for assessment of axial load capacity of piles : [technical summary].
2012-01-01
The dynamic response of a pile during driving is very : complex, involving the interactions of the hammer, cushion, : pile and soil during application of an impact load. : The first analysis aimed at simulating a hammer blow on : a pile was published...
Huy, N.Q.
2010-01-01
Pile testing, which plays an importance role in the field of deep foundation design, is performed by static and non-static methods to provide information about the following issues: (Poulos, 1998) - The ultimate capacity of a single pile. - The load-displacement behavior of a pile. - The performance
Uplift Capacity of Inclined Underreamed Piles Subjected to Vertical Load
Rahman, Md. Akilur; Sengupta, Siddhartha
2017-12-01
Many offshore structures are subjected to overturning moments due to wind load, wave pressure, and ship impacts. Inclined (batter) piles are used to support such structures, and to carry the horizontal and vertical loads resulted from the overturning moments. Though studies have been done with inclined piles having no underream bulb, little information is available in the literature about estimating the uplift capacity of inclined underreamed piles. In the present study laboratory experiments have been done with vertically loaded model piles having no underream as well as with one and two underreams. The piles were positioned at angle of inclination of θ = 0°, 10°, 20°, 30° (with vertical); and placed in locally available sand under vertical uplift load. Three different pile stem diameters (D = 20, 25, and 35 mm) were used. The corresponding pile length to stem diameter (l/D) ratio were 18, 14, and 10 respectively. Experiments had been conducted with two relative different densities (45 and 70%) of sand. The failure uplift loads were obtained in each case. It had been found that for inclined piles increase in number of underream bulbs from 0 to 2 was quite effective in resisting uplift loads corresponding to piles having l/D equals to 10. The percentage decreases in uplift capacity corresponding to increase in inclination angle were more pronounced for piles with double underreams.
Friction effects on lateral loading behavior of rigid piles
DEFF Research Database (Denmark)
Zania, Varvara; Hededal, Ole
2012-01-01
The adequacy of the p -y curves used in the current practice for the design of rigid pile foundations with large diameter, like in the case of monopile foundations of offshore wind turbines, has been widely questioned. The current study aims at analyzing the lateral behavior of rigid piles, while...... the lateral capacity of the pile. The obtained p - y curves demonstrate the importance of the aforementioned parameters in the design of rigid piles, as the reduction of friction along the interface reduces not only the ultimate load but also the stiffness of the soil-pile response. Read More: http...
Static Tension Tests on Axially Loaded Pile Segments in Sand
DEFF Research Database (Denmark)
Thomassen, Kristina; Andersen, Lars Vabbersgaard; Ibsen, Lars Bo
This paper provides laboratory test results of static axially loaded piles in sand. With a newly developed test setup, the pile-soil interface friction was investigated by using an open-ended steel pile segment with a diameter of 0.5 m. Use of a pile length of 1 m enabled the pile-soil interface...... friction to be analyzed at a given soil horizon while increasing the vertical effective stress in the sand. Test results obtained by this approach can be analyzed as single t-z curves and compared to predictions of unit shaft friction from current design methods for offshore foundations. The test results...
Modeling Laterally Loaded Single Piles Accounting for Nonlinear Soil-Pile Interactions
Directory of Open Access Journals (Sweden)
Maryam Mardfekri
2013-01-01
Full Text Available The nonlinear behavior of a laterally loaded monopile foundation is studied using the finite element method (FEM to account for soil-pile interactions. Three-dimensional (3D finite element modeling is a convenient and reliable approach to account for the continuity of the soil mass and the nonlinearity of the soil-pile interactions. Existing simple methods for predicting the deflection of laterally loaded single piles in sand and clay (e.g., beam on elastic foundation, p-y method, and SALLOP are assessed using linear and nonlinear finite element analyses. The results indicate that for the specific case considered here the p-y method provides a reasonable accuracy, in spite of its simplicity, in predicting the lateral deflection of single piles. A simplified linear finite element (FE analysis of piles, often used in the literature, is also investigated and the influence of accounting for the pile diameter in the simplified linear FE model is evaluated. It is shown that modeling the pile as a line with beam-column elements results in a reduced contribution of the surrounding soil to the lateral stiffness of the pile and an increase of up to 200% in the predicted maximum lateral displacement of the pile head.
Field Test of Driven Pile Group under Lateral Loading
Gorska, Karolina; Rybak, Jaroslaw; Wyjadlowski, Marek
2017-12-01
All the geotechnical works need to be tested because the diversity of soil parameters is much higher than in other fields of construction. Horizontal load tests are necessary to determine the lateral capacity of driven piles subject to lateral load. Various load tests were carried out altogether on the test field in Kutno (Poland). While selecting the piles for load tests, different load combinations were taken into account. The piles with diverse length were chosen, on the basis of the previous tests of their length and integrity. The subsoil around the piles consisted of mineral soils: clays and medium compacted sands with the density index ID>0.50. The pile heads were free. The points of support of the “base” to which the dial gauges (displacement sensors) were fastened were located at the distance of 0.7 m from the side surface of the pile loaded laterally. In order to assure the independence of measurement, additional control (verifying) geodetic survey of the displacement of the piles subject to the load tests was carried out (by means of the alignment method). The trial load was imposed in stages by means of a hydraulic jack. The oil pressure in the actuator was corrected by means of a manual pump in order to ensure the constant value of the load in the on-going process of the displacement of the pile under test. On the basis of the obtained results it is possible to verify the numerical simulations of the behaviour of piles loaded by a lateral force.
Load rating and retrofit testing of bridge timber piles subjected to eccentric loading.
2012-11-01
This report first evaluated the load rating procedure currently in use by the Illinois Department of Transportation (IDOT) for rating timber : piles supporting multiple-span, simply supported bridges. For simplicity, these piles are often rated under...
The effect of loading rate on pile bearing capacity of saturated sand
Archeewa, E.
2005-01-01
Pile load tests are commonly used by engineers to determine its bearing capacity. At present, there are three methods of pile load tests: the static, the dynamic and the quasi-static test. The static pile load test is done by applying an axial load on the pile with a long duration. The dynamic and
Rapid pile load tests in the geotechnical centrifuge
Holscher, P.; Van Tol, A.F.; Huy, N.Q.
2012-01-01
Centrifiige experiments were carried out to gain insight into the factors that affect the mobilized resistance during rapid load testing on piles in sand. The influence of generated pore water pressure during rapid load tests is shidied, and its effect on the commonly used unloadmg point method to
Centrifuge modelling of a laterally cyclic loaded pile
DEFF Research Database (Denmark)
Klinkvort, Rasmus Tofte; Leth, Caspar Thrane; Hededal, Ole
2010-01-01
A total number of 9 static and 6 cyclic centrifuge tests on laterally loaded piles in very dense, dry sand was erformed. The prototype dimensions of the piles were 1 meter in diameter and penetration depths varying from 6 to 10 meters. The static tests were used to investigate the initial subgrade...... reaction modulus and as a reference for cyclic tests. For the cyclic tests the accumulation of deflections and the change in secant stiffness of the soil from repetitive loading were investigated. From all the tests carried out accumulations of deflections were seen. rom the centrifuge tests it was seen...
Statistical Estimation of Subgrade Reaction Coefficient For Horizontally Loaded Piles
International Nuclear Information System (INIS)
Honjo, Yusuke; Zaika, Yulvi; Pokharel, Gyaneswor
2002-01-01
Appropriate horizontal subgrade reaction (k h ) is required to evaluate stress and displacement in horizontal loading pile. In order to obtain more accurate prediction of pile behavior, statistical analysis is employed. Based on 21 data set gathered on horizontal loading piles, inverse analysis and regression analysis are carried out. The main value and uncertainty are obtained by inverse analysis, could be employed in the regression analysis. The relationship between the lateral resistant constant (k c ) and SPT N value takes into account in correlated and uncorrelated condition. The results are compared with Port and Harbor Technical Research Institute (JPHA, 1999) and Japan Highway Bridge Specification IV (JRA, 1996). The computed values are found to be very close to the JPHA line and within the range of JRA lines in diameter 0.5 m and 2 m
Crack path in aeronautical titanium alloy under ultrasonic torsion loading
Directory of Open Access Journals (Sweden)
A. Nikitin
2016-01-01
Full Text Available This paper discusses features of fatigue crack initiation and growth in aeronautical VT3-1 titanium alloy under pure torsion loading in gigacycle regime. Two materials: extruded and forged VT3-1 titanium alloys were studied. Torsion fatigue tests were performed up to fatigue life of 109 cycles. The results of the torsion tests were compared with previously obtained results under fully reversed axial loading on the same alloys. It has been shown that independently on production process as surface as well subsurface crack initiation may appear under ultrasonic torsion loading despite the maximum stress amplitude located at the specimen surface. In the case of surface crack initiation, a scenario of crack initiation and growth is similar to HCF regime except an additional possibility for internal crack branching. In the case of subsurface crack, the initiation site is located below the specimen surface (about 200 μm and is not clearly related to any material flaw. Internal crack initiation is produced by shear stress in maximum shear plane and early crack growth is in Mode II. Crack branching is limited in the case of internal crack initiation compared to surface one. A typical ‘fish-eye’ crack can be observed at the torsion fracture surface, but mechanism of crack initiation seems not to be the same than under axial fatigue loading.
Residual torsional properties of composite shafts subjected to impact loadings
International Nuclear Information System (INIS)
Sevkat, Ercan; Tumer, Hikmet
2013-01-01
Highlights: • Impact loading reduces the torsional strength of composite shaft. • Impact energy level determines the severity of torsional strength reduction. • Hybrid composite shafts can be manufactured by mixing two types of filament. • Maximum torque capacity of shafts can be estimated using finite element method. - Abstract: This paper presents an experimental and numerical study to investigate residual torsional properties of composite shafts subjected to impact loadings. E-glass/epoxy, carbon/epoxy and E-glass–carbon/epoxy hybrid composite shafts were manufactured by filament winding method. Composite shafts were impacted at 5, 10, 20 and 40 J energy levels. Force–time and energy–time histories of impact tests were recorded. One composite shaft with no impact, and four composite shafts with impact damage, five in total, were tested under torsion. Torque-twisting angle relations for each test were obtained. Reduction at maximum torque and maximum twisting angle induced by impact loadings were calculated. While 5 J impact did not cause significant reduction at maximum torque and maximum twisting angle, remaining impact loadings caused 34–67% reduction at maximum torque, and 30–61% reduction at maximum twisting angle. Reductions increased with increasing energy levels and varied depending on the material of composite shafts. The 3-D finite element (FE) software, Abaqus, incorporated with an elastic orthotropic model, was then used to simulate the torsion tests. Good agreement between experimental and numerical results was achieved
Directory of Open Access Journals (Sweden)
Denise-Penelope N. Kontoni
2018-01-01
Full Text Available An existing riverine platform in Egypt, together with its pile group foundation, is analyzed under environmental loads using 3D FEM structural analysis software incorporating soil-pile interaction. The interaction between the transfer plate and the piles supporting the platform is investigated. Two connection conditions were studied assuming fixed or hinged connection between the piles and the reinforced concrete platform for the purpose of comparison of the structural behavior. The analysis showed that the fixed or hinged connection condition between the piles and the platform altered the values and distribution of displacements, normal force, bending moments, and shear forces along the length of each pile. The distribution of piles in the pile group affects the stress distribution on both the soil and platform. The piles were found to suffer from displacement failure rather than force failure. Moreover, the resulting bending stresses on the reinforced concrete plate in the case of a fixed connection between the piles and the platform were almost doubled and much higher than the allowable reinforced concrete stress and even exceeded the ultimate design strength and thus the environmental loads acting on a pile-supported riverine offshore platform may cause collapse if they are not properly considered in the structural analysis and design.
THREE-DIMENSIONAL NONLINEAR FINITE ELEMENT MODELING FOR LATERALLY LOADED VERTICAL PILES
Directory of Open Access Journals (Sweden)
M. Kubilay KELESOĞLU
2006-01-01
Full Text Available This paper presents a study for laterally loaded free head concrete piles using the finite element method (FEM. The finite element mesh is constituted from three-dimensional elements. The pile and soil boundary are defined cylindrically while lateral load is defined as single concentrated load from the top of the pile head. Various types of soil and pile properties are analysed and the load-deformation curves for different types of soils namely, sands and clays are evaluated.
Directory of Open Access Journals (Sweden)
Yan-yan Cai
2018-01-01
Full Text Available Lateral displacement of pile foundation is crucial to the safety of an overall structure. In this study, a numerical simulation on the lateral displacement of pile foundation under stacking loads was conducted to determine its relation with different influencing factors. Simulation results demonstrated that stacking loads at the pile side mostly influence the lateral displacement of pile foundation. The lateral displacement of pile foundation increases by one order of magnitude when the stacking loads increase from 100 kPa to 300 kPa. Other influencing factors are less important than stacking loads. Lateral displacements of the pile body and at the pile top can be reduced effectively by increasing the deformation modulus of surface soil mass, reducing the thickness of soft soil, and expanding pile diameter. Our analysis indicates that a nonlinear relationship exists between the lateral displacement at the pile top and the pile diameter. The lateral resistance of the pile body can be enhanced by coupling the stacking load along piles and the axial force at the pile top. An actual large-scale engineering project was chosen to simulate the effects of postconstructed embankment on lateral displacement and axial force of bridge pile foundation under different construction conditions and to obtain the lateral displacement of the pile body and the negative frictional resistance caused by soft soil compression under stacking loads. On the basis of the calculated results, engineering safety and stability were evaluated, and a guide for the design and construction was proposed.
Numerical Simulation for the Soil-Pile-Structure Interaction under Seismic Loading
Directory of Open Access Journals (Sweden)
Lifeng Luan
2015-01-01
Full Text Available Piles are widely used as reinforcement structures in geotechnical engineering designs. If the settlement of the soil is greater than the pile, the pile is pulled down by the soil, and negative friction force is produced. Previous studies have mainly focused on the interaction of pile-soil under static condition. However, many pile projects are located in earthquake-prone areas, which indicate the importance of determining the response of the pile-soil structure under seismic load. In this paper, the nonlinear, explicit, and finite difference program FLAC3D, which considers the mechanical behavior of soil-pile interaction, is used to establish an underconsolidated soil-pile mode. The response processes of the pile side friction force, the pile axial force, and the soil response under seismic load are also analyzed.
2009-12-01
During earthquake excitations, reinforced concrete bridge columns can be subjected to a combination of axial load, shear force, : flexural moments, and torsional moments. The torsional moment can be much more significant in columns of bridges that ar...
Three dimensional modeling of laterally loaded pile groups resting in sand
Directory of Open Access Journals (Sweden)
Amr Farouk Elhakim
2016-04-01
Full Text Available Many structures often carry lateral loads due to earth pressure, wind, earthquakes, wave action and ship impact. The accurate predictions of the load–displacement response of the pile group as well as the straining actions are needed for a safe and economic design. Most research focused on the behavior of laterally loaded single piles though piles are most frequently used in groups. Soil is modeled as an elastic-perfectly plastic model using the Mohr–Coulomb constitutive model. The three-dimensional Plaxis model is validated using load–displacement results from centrifuge tests of laterally loaded piles embedded in sand. This study utilizes three dimensional finite element modeling to better understand the main parameters that affect the response of laterally loaded pile groups (2 × 2 and 3 × 3 pile configurations including sand relative density, pile spacing (s = 2.5 D, 5 D and 8 D and pile location within the group. The fixity of the pile head affects its load–displacement under lateral loading. Typically, the pile head may be unrestrained (free head as the pile head is allowed to rotate, or restrained (fixed head condition where no pile head rotation is permitted. The analyses were performed for both free and fixed head conditions.
Investigation of Redistribution of Pile Foundation Forces Under Successive Loading of Its Elements
Sedin, Vladimir; Bikus, Kateryna; Kovba, Vladislav
2017-12-01
Redistribution of pile foundation forces under successive loading of its elements was investigated under laboratory conditions. A segment of pile foundation model was taken for use in the case study. Load tests on the pile foundation model segment, without joining its elements (pile and plate, which turns into grillage) and based on different combinations of static loadings were conducted. This proved that the loading of a plate causes skin friction on some length of the pile side surface as well as providing additional loading and settlement. Test results have shown that application of successive elements enables the foundation to carry loads up to 13% higher than in the case of a standard pile foundation loading with the same settlement rates.
2016-11-01
mudline. The piles are 2 ft diameter, concrete-filled pipe piles. Fortunately, the CPGA software discussed subsequently had enough flexibility to...being an axial stiffness modifier, A designating the cross-sectional area of the concrete-filled pipe pile, E designating the pile’s (composite...stiffness modifier, A designates the cross-sectional area of the concrete-filled pipe pile, E designates its (composite) Young’s Modulus, and Le is the
Experimental study on performance of laterally loaded plumb and battered piles in layered sand
Directory of Open Access Journals (Sweden)
Bushra S. Albusoda
2017-09-01
Full Text Available This study introduces a series of single and pile group model tests subjected to lateral loads in . multilayered sand from Karbala, Iraq. The aim of this study is to investigate: the performance of the pile groups subjected to lateral loads; in which the pile batter inclination angle is changed; the effect of pile spacing (s/d ratio, the influence of using different number of piles and pile group configuration. Results revealed that the performance of single negative (Reverse Battered piles with inclination of 10° and 20° show a gain of 32% and 76 % in the ultimate lateral capacity over the regular ones. For pile groups, the use of a combination of regular, negative and positive battered piles in different angles of inclination within the same group shows a significant increase in the ultimate lateral load carrying capacity. Increasing the spacing between piles in groups of the same category shows an increase in the group efficiency, also changing the piles number within the group by using different patterns will influence the ultimate lateral resistance of the pile group.
APPLICATION OF THE METHOD OF DIMENSIONALITY REDUCTION TO CONTACTS UNDER NORMAL AND TORSIONAL LOADING
Directory of Open Access Journals (Sweden)
Emanuel Willert
2015-08-01
In view of all this, the torsional contact problems have been disregarded until now, although it is known that torsion is a major reason of wear and possible failure of system components. Therefore, in the present paper, we extend the MDR to contacts of axisymmetric profiles under superimposed normal and torsional loading.
Horizontal Displacement Control in Course of Lateral Loading of a Pile in a Slope
Muszyński, Zbigniew; Rybak, Jarosław
2017-10-01
Standard procedures concerning axial and lateral capacity testing of foundation piles usually consist of a single loading cycle. Constant load steps or constant settlement increments may be applied in the test. Such a procedure significantly differs from in-situ conditions of pile loading, which can be cyclic – especially in the case of the constructions, which are subject to wind load. Several tests were performed to observe the behaviour of the driven piles subject to fast cyclic loading in horizontal direction (lateral load). The manner in which the load tests were performed made it possible to determine the displacement of the 40×40 cm pile in the least favourable loading scheme, i.e. the lateral load capacity of the pile oriented towards the embankment slope. The piles were originally designed for the foundation of noise barriers along the highway. Some of the piles were broken in course of driving and a cautious check of their behaviour under load was requested before the assembling of the entire structure. Eight load tests were carried out altogether. While selecting the piles for further load tests, the representativeness of the random sample was taken into account. The piles with diverse cross section and length were chosen, on the basis of the previous low strain tests of their integrity. The subsoil around the piles consisted of medium and coarse sands with the density index ID>0.67. The pile heads were free. The points of support of the reference frame to which the sensors were fastened were located at the distance of 0.6 m from the side surface of the pile loaded laterally. In order to assure the independence of measurement, additional control (verifying) geodetic survey of the displacements of the piles subject to the load tests was carried out. The research conducted at Wroclaw University of Technology made it possible to collect and summarize the results of displacement measurements in course of static load testing of driven piles in a slope
2009-12-01
Reinforced concrete (RC) columns of skewed and curved bridges with unequal spans and column heights can be subjected to : combined loading including axial, flexure, shear, and torsion loads during earthquakes. The combination of axial loads, shear : ...
Experimental Comparison of Non-Slender Piles under Static Loading and under Cyclic Loading in Sand
DEFF Research Database (Denmark)
Sørensen, Søren Peder Hyldal; Ibsen, Lars Bo
2012-01-01
An experimental evaluation of the pile behavior of non-slender piles exposed to static and cyclic lateral loading is presented. The tests were conducted in a pressure tank at Aalborg University. This enabled the possibility of applying an overburden pressure to the soil. When conducting small......-scale tests at 1-g the determination of the friction angle and the Young’s modulus of elasticity of the soil are difficult and further these soil parameters varies greatly with depth. These uncertainties were avoided by application of an overburden pressure....
An experimental study on pile spacing effects under lateral loading in sand.
Khari, Mahdy; Kassim, Khairul Anuar; Adnan, Azlan
2013-01-01
Grouped and single pile behavior differs owing to the impacts of the pile-to-pile interaction. Ultimate lateral resistance and lateral subgrade modulus within a pile group are known as the key parameters in the soil-pile interaction phenomenon. In this study, a series of experimental investigation was carried out on single and group pile subjected to monotonic lateral loadings. Experimental investigations were conducted on twelve model pile groups of configurations 1 × 2, 1 × 3, 2 × 2, 3 × 3, and 3 × 2 for embedded length-to-diameter ratio l/d = 32 into loose and dense sand, spacing from 3 to 6 pile diameter, in parallel and series arrangement. The tests were performed in dry sand from Johor Bahru, Malaysia. To reconstruct the sand samples, the new designed apparatus, Mobile Pluviator, was adopted. The ultimate lateral load is increased 53% in increasing of s/d from 3 to 6 owing to effects of sand relative density. An increasing of the number of piles in-group decreases the group efficiency owing to the increasing of overlapped stress zones and active wedges. A ratio of s/d more than 6d is large enough to eliminate the pile-to-pile interaction and the group effects. It may be more in the loose sand.
An Experimental Study on Pile Spacing Effects under Lateral Loading in Sand
Khari, Mahdy; Kassim, Khairul Anuar; Adnan, Azlan
2013-01-01
Grouped and single pile behavior differs owing to the impacts of the pile-to-pile interaction. Ultimate lateral resistance and lateral subgrade modulus within a pile group are known as the key parameters in the soil-pile interaction phenomenon. In this study, a series of experimental investigation was carried out on single and group pile subjected to monotonic lateral loadings. Experimental investigations were conducted on twelve model pile groups of configurations 1 × 2, 1 × 3, 2 × 2, 3 × 3, and 3 × 2 for embedded length-to-diameter ratio l/d = 32 into loose and dense sand, spacing from 3 to 6 pile diameter, in parallel and series arrangement. The tests were performed in dry sand from Johor Bahru, Malaysia. To reconstruct the sand samples, the new designed apparatus, Mobile Pluviator, was adopted. The ultimate lateral load is increased 53% in increasing of s/d from 3 to 6 owing to effects of sand relative density. An increasing of the number of piles in-group decreases the group efficiency owing to the increasing of overlapped stress zones and active wedges. A ratio of s/d more than 6d is large enough to eliminate the pile-to-pile interaction and the group effects. It may be more in the loose sand. PMID:24453900
Analytical Approach for Load Capacity of Large Diameter Bored Piles Using Field Data
Directory of Open Access Journals (Sweden)
Alaa Dawood Salman
2015-08-01
Full Text Available An analytical approach based on field data was used to determine the strength capacity of large diameter bored type piles. Also the deformations and settlements were evaluated for both vertical and lateral loadings. The analytical predictions are compared to field data obtained from a proto-type test pile used at Tharthar –Tigris canal Bridge. They were found to be with acceptable agreement of 12% deviation. Following ASTM standards D1143M-07e1,2010, a test schedule of five loading cycles were proposed for vertical loads and series of cyclic loads to simulate horizontal loading .The load test results and analytical data of 1.95m in diameter test pile proved efficiently to carry a working load of 450 tons. The calculated lateral displacements based on a specified coefficient of subgrade reaction are compared to the measured values from dial gauges and strain gauges placed at various locations along the length of the pile.
Effect of relative pile’s stiffness on lateral pile response under loading of large eccentricity
DEFF Research Database (Denmark)
Zania, Varvara; Hededal, Ole; Klinkvort, R.T.
2015-01-01
The wide application of monopiles as foundations for offshore wind turbines has raised the issue of the suitability of the p –y curves proposed by API for lateral pile loading, since the latter were developed after full-scale tests on flexible and slender piles. This study investigates the role o...
Development of p-y curves of laterally loaded piles in cohesionless soil.
Khari, Mahdy; Kassim, Khairul Anuar; Adnan, Azlan
2014-01-01
The research on damages of structures that are supported by deep foundations has been quite intensive in the past decade. Kinematic interaction in soil-pile interaction is evaluated based on the p-y curve approach. Existing p-y curves have considered the effects of relative density on soil-pile interaction in sandy soil. The roughness influence of the surface wall pile on p-y curves has not been emphasized sufficiently. The presented study was performed to develop a series of p-y curves for single piles through comprehensive experimental investigations. Modification factors were studied, namely, the effects of relative density and roughness of the wall surface of pile. The model tests were subjected to lateral load in Johor Bahru sand. The new p-y curves were evaluated based on the experimental data and were compared to the existing p-y curves. The soil-pile reaction for various relative density (from 30% to 75%) was increased in the range of 40-95% for a smooth pile at a small displacement and 90% at a large displacement. For rough pile, the ratio of dense to loose relative density soil-pile reaction was from 2.0 to 3.0 at a small to large displacement. Direct comparison of the developed p-y curve shows significant differences in the magnitude and shapes with the existing load-transfer curves. Good comparison with the experimental and design studies demonstrates the multidisciplinary applications of the present method.
Rat disc torsional mechanics: effect of lumbar and caudal levels and axial compression load.
Espinoza Orías, Alejandro A; Malhotra, Neil R; Elliott, Dawn M
2009-03-01
Rat models with altered loading are used to study disc degeneration and mechano-transduction. Given the prominent role of mechanics in disc function and degeneration, it is critical to measure mechanical behavior to evaluate changes after model interventions. Axial compression mechanics of the rat disc are representative of the human disc when normalized by geometry, and differences between the lumbar and caudal disc have been quantified in axial compression. No study has quantified rat disc torsional mechanics. Compare the torsional mechanical behavior of rat lumbar and caudal discs, determine the contribution of combined axial load on torsional mechanics, and compare the torsional properties of rat discs to human lumbar discs. Cadaveric biomechanical study. Cyclic torsion without compressive load followed by cyclic torsion with a fixed compressive load was applied to rat lumbar and caudal disc levels. The apparent torsional modulus was higher in the lumbar region than in the caudal region: 0.081+/-0.026 (MPa/degrees, mean+/-SD) for lumbar axially loaded; 0.066+/-0.028 for caudal axially loaded; 0.091+/-0.033 for lumbar in pure torsion; and 0.056+/-0.035 for caudal in pure torsion. These values were similar to human disc properties reported in the literature ranging from 0.024 to 0.21 MPa/degrees. Use of the caudal disc as a model may be appropriate if the mechanical focus is within the linear region of the loading regime. These results provide support for use of this animal model in basic science studies with respect to torsional mechanics.
Experimental Comparison of Statically and Cyclically Loaded Non-Slender Piles in Sand
DEFF Research Database (Denmark)
Sørensen, Søren Peder Hyldal; Ibsen, Lars Bo
and hence the effective stresses in the soil have been increased homogeneously. The tests have been conducted in a pressure tank at Aalborg University. A total of 29 quasi-static tests and 14 cyclic tests have been conducted on laterally loaded piles situated in sand. Aluminium pipe piles instrumented...... used as foundation for modern offshore wind energy converters. The aim of the present work is to investigate the pile behaviour for non-slender piles by means of small-scale testing. The pile behaviour is investigated and compared for both static and cyclic loading. When conducting small-scale tests...... the effective stresses in the soil will be low and vary linearly with depth. As a consequence of this the soil parameters will vary greatly with depth and the determination of soil parameters is subject to great uncertainties. To overcome these uncertainties an overburden pressure, P0, has been applied...
Development of a new simplified load testing method of a pile. Kui no shinsaika shikenho no kaihatsu
Energy Technology Data Exchange (ETDEWEB)
Aoki, H.; Maruyama, O. (Japan Railway Construction Public Corp., Tokyo (Japan)); Fujioka, T. (Chiyoda Corp., Tokyo (Japan)); Kato, H. (Daido Concrete Co. Ltd., Tokyo (Japan))
1992-10-15
It is preferable to use a vertically loading test to verify bearing power of a pile. However, the conventional standard loading test could not be used easily because of much expense required for reactive piles and a loading device. Accordingly, a new load testing method was developed. The method places a load on a jack mounted initially near a pile tip, and measures the load on the jack, its vertical displacement and the strain and displacement in the pile including the pile head at each depth. Thus, the relationship between circumferential friction force at each part of the pile and the displacement, and the relationship between the jack load and the downward displacement are derived, which are converted to the relationship between the load on the pile head against the pile head loading and the amount of subsidence, using a load transmission analysis. The method features no necessity of reactive piles or loading girders, capability of measuring separately the circumferential friction force and the tip bearing power, safety, short construction time, and inexpensiveness. The jacks include types that are recovered after a test and not recovered. This new load testing method has been used on 18 different kinds of piles, in addition to verification test at sandy alluvial fan areas between Takasaki and Karuizawa in the planned Hokuriku Shinkansen line. 11 figs.
Research on torsional friction behavior and fluid load support of PVA/HA composite hydrogel.
Chen, Kai; Zhang, Dekun; Yang, Xuehui; Cui, Xiaotong; Zhang, Xin; Wang, Qingliang
2016-09-01
Hydrogels have been extensively studied for use as synthetic articular cartilage. This study aimed to investigate (1) the torsional friction contact state and the transformation mechanism of PVA/HA composite hydrogel against CoCrMo femoral head and (2) effects of load and torsional angle on torsional friction behavior. The finite element method was used to study fluid load support of PVA/HA composite hydrogel. Results show fluid loss increases gradually of PVA/HA composite hydrogel with torsional friction time, leading to fluid load support decreases. The contact state changes from full slip state to stick-slip mixed state. As the load increases, friction coefficient and adhesion zone increase gradually. As the torsional angle increases, friction coefficient and slip trend of the contact interface increase, resulting in the increase of the slip zone and the reduction of the adhesion zone. Fluid loss increases of PVA/HA composite hydrogel as the load and the torsional angle increase, which causes the decrease of fluid load support and the increase of friction coefficient. Copyright © 2016 Elsevier Ltd. All rights reserved.
Improved Design Basis for Laterally Loaded Large Diameter Pile
DEFF Research Database (Denmark)
Leth, Caspar Thrane
in dry sand by use of centrifuge modelling and to compare the findings with the standard p-y curves. It has been chosen to apply piles with an embedment length of 6 to 10 times the diameter of the applied piles. The general static behaviour of monopiles in dry sand has based on centrifuge tests been...... initial response and a higher ultimate capacity. The initial stiffness of the soil-structure interaction measured in the centrifuge tests, equivalent to initial stiffness of p-y curves, shows a dependency of depth and diameter. Control issues in relation to cyclic tests have resulted in tests...... on the structure and the productivity of the turbine. Current design practice for monopiles are based on p-y curves developed for slender piles with a diameter of 0.6 m. The focus on the structure stiffness has entailed a significant research on the soil-structure interaction for large diameter monopiles...
Synergism Analysis of Bedding Slope with Piles and Anchor Cable Support under Sine Wave Vehicle Load
Directory of Open Access Journals (Sweden)
Li Dan-Feng
2016-01-01
Full Text Available Slope instability under dynamic load is the technical difficulty in the engineering; the evaluation of slope stability under dynamic load and the control of dynamic load is particularly important. In this paper, taking the right side slope of K27+140 m~380 m typical section (K27 slope for short in Chongqing Fuling-Fengdu-Shizhu expresses highway as an example to calculate and analyze. The K27 slope is under sinusoidal vehicle load and supported by anchor cable and antislide pile to resist downslide strength; at the same time, the combined effect of them is studied. Three-dimensional finite element methodology (FEM is used to simulate the bedding slope with piles and anchor cable support; furthermore, the eigenvalue can be obtained. In order to reduce error of the elastic boundary conditions caused by the reflection effect of wavelengths, the combination of Lysmer surface viscous boundary and traditional ground support boundaries is utilized to analyze and calculate the time-histories during bedding slope under dynamic load. The dynamic response of pile anchor support to resist sliding force is obtained. The concept of the pile anchor supporting coordinate interval is put forward. Furthermore, it is verified that the pile anchor supporting coordinate interval can be used to evaluate the stability of the slope under dynamic load and provide a new method for the control of the dynamic load.
Directory of Open Access Journals (Sweden)
Stefano Stacul
2018-02-01
Full Text Available A Boundary Element Method (BEM approach was developed for the analysis of pile groups. The proposed method includes: the non-linear behavior of the soil by a hyperbolic modulus reduction curve; the non-linear response of reinforced concrete pile sections, also taking into account the influence of tension stiffening; the influence of suction by increasing the stiffness of shallow portions of soil and modeled using the Modified Kovacs model; pile group shadowing effect, modeled using an approach similar to that proposed in the Strain Wedge Model for pile groups analyses. The proposed BEM method saves computational effort compared to more sophisticated codes such as VERSAT-P3D, PLAXIS 3D and FLAC-3D, and provides reliable results using input data from a standard site investigation. The reliability of this method was verified by comparing results from data from full scale and centrifuge tests on single piles and pile groups. A comparison is presented between measured and computed data on a laterally loaded fixed-head pile group composed by reinforced concrete bored piles. The results of the proposed method are shown to be in good agreement with those obtained in situ.
Analytical investigation of pile-soil interaction in sand under axial and lateral loads
Abdel-Mohti, Ahmed; Khodair, Yasser
2014-03-01
This paper presents a numerical study of pile-soil interaction due to application of axial and lateral loads to piles in sand. The pile-soil interaction was analyzed using the finite difference (FD) software LPILE and two finite element (FE) software. The three-dimensional (3D) FE models of pile-soil interaction have been created using Abaqus/Cae and SAP2000. Various types of soft soil were studied, such as loose, medium, and dense sand. A lateral displacement of 2 cm was applied to the top of the pile while maintaining a zero slope in a guided fixation. A combined lateral and axial load of 300 kN was also studied. The paper compared between the bending moments and lateral displacements along the depth of the pile obtained from the FD solutions and FE analyses. A parametric study was conducted to study the effect of crucial design parameters such as the modulus of elasticity of soil and the number of nonlinear soil springs that can be used to model the soil. A good agreement between the results obtained by the FE models and the FD solution was observed. Also, the FE models were capable of predicting the pile-soil interaction for all types of soft soil.
Numerical analysis of energy piles under different boundary conditions and thermal loading cycles
Directory of Open Access Journals (Sweden)
Khosravi Ali
2016-01-01
Full Text Available The thermo- mechanical behavior of energy piles has been studied extensively in recent years. In the present study, a numerical model was adapted to study the effect of various parameters (e.g. heating/cooling temperature, head loading condition and soil stiffness on the thermo-mechanical behavior of an energy pile installed in unsaturated sandstone. The results from the simulations were compared with measurements from a thermal response test on a prototype energy pile installed beneath a 1-story building at the US Air Force Academy (USAFA in Colorado Springs, CO. A good agreement was achieved between the results obtained from the prototype and the numerical models. A parametric evaluation were also carried out which indicated the significance of the stiffness of the unsaturated sandstone and pile’s head loading condition on stress-strain response of the energy pile during heating/cooling cycles.
Biomechanics of lumbosacral spinal fusion in combined compression-torsion loads.
Yang, S W; Langrana, N A; Lee, C K
1986-11-01
The current study investigates the stabilizing effects of three different types of spinal fusion to the juxta-free motion segments and to the fused segment of the lumbosacral spine under combined compression-torsion loads. Sixteen fresh human cadaver lumbosacral spines were tested under a simulated physiologic loading condition. The relative movements of the motion segments, as well as the angular rotations and the center of rotation were then computed and analyzed. The average torsional stiffness of the unfused three-motion segment was found to be 2.35 nm/degree. After fusion, the torsional stiffness did not increase significantly. Under the compression-torsional load, the anterior and bilateral-lateral fusions provided adequate stabilizing effect on the fused segment. The posterior fusion provided the least amount of stabilizing effect. These findings are similar to the results of the compression-bending experiment. Whereas the compression-bending loads produced significantly increased stress at the juxta-free segments, the compression-torsional loads did not produce any significant amount of increase in torsional stress at the juxta-free segments.
Development of p-y Curves of Laterally Loaded Piles in Cohesionless Soil
Khari, Mahdy; Kassim, Khairul Anuar; Adnan, Azlan
2014-01-01
The research on damages of structures that are supported by deep foundations has been quite intensive in the past decade. Kinematic interaction in soil-pile interaction is evaluated based on the p-y curve approach. Existing p-y curves have considered the effects of relative density on soil-pile interaction in sandy soil. The roughness influence of the surface wall pile on p-y curves has not been emphasized sufficiently. The presented study was performed to develop a series of p-y curves for single piles through comprehensive experimental investigations. Modification factors were studied, namely, the effects of relative density and roughness of the wall surface of pile. The model tests were subjected to lateral load in Johor Bahru sand. The new p-y curves were evaluated based on the experimental data and were compared to the existing p-y curves. The soil-pile reaction for various relative density (from 30% to 75%) was increased in the range of 40–95% for a smooth pile at a small displacement and 90% at a large displacement. For rough pile, the ratio of dense to loose relative density soil-pile reaction was from 2.0 to 3.0 at a small to large displacement. Direct comparison of the developed p-y curve shows significant differences in the magnitude and shapes with the existing load-transfer curves. Good comparison with the experimental and design studies demonstrates the multidisciplinary applications of the present method. PMID:24574932
Physical scale modeling of single free head piles under lateral loading in cohesive soils
Directory of Open Access Journals (Sweden)
Edgar Leonardo Salamanca-Medina
2017-06-01
Full Text Available This paper presents the results of the small scale modeling of free head wood piles under horizontal loading in cohesive soils, tested in order to compare the results with analytical models proposed by various authors. Characteristic Load (CLM and P-Y Curves methods were used for the prediction of lateral deflections at the head of the piles and the method proposed by Broms for estimating the ultimate lateral load. These predictions were compared with the results of the physical modeling, obtaining a good approximation between them.
Optimum Design of Composite Sandwich Structures Subjected to Combined Torsion and Bending Loads
Li, Xiang; Li, Gangyan; Wang, Chun H.; You, Min
2012-06-01
This research is motivated by the increase use of composite sandwich structures in a wide range of industries such as automotive, aerospace and civil infrastructure. To maximise stiffness at minimum weight, the paper develops a minimum weight optimization method for sandwich structure under combined torsion and bending loads. We first extend the minimum-weight design of sandwich structures under bending load to the case of torsional deformation and then present optimum solutions for the combined requirements of both bending and torsional stiffness. Three design cases are identified for a sandwich structure required to meet multiple design constraints of torsion and bending stiffness. The optimum solutions for all three cases are derived. To illustrate the newly developed optimum design solutions, numerical examples are presented for sandwich structures made of either isotropic face skins or orthotropic composite face skins.
EQUATIONS OF NONLINEAR SOIL DAMAGE BASED ON RESULTS OF TESTING OF LATERALLY LOADED PILE MODELS
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Buslov Anatoliy Semenovich
2012-12-01
Full Text Available Results of testing of laterally loaded pile models demonstrate that the "load -to-displacement" dependency has a nonlinear character. This dependency may be regarded as linear within the interval of (0.2…0.3 Pul only. Tests were performed in a box with displacement indicators and power equipment. The pile model length was 200 mm, and its diameter was 40 mm. A hollow steel tube was used as the material for tested piles. Based on the analysis of testing results, a pattern of the non-linear damage of the base was formulated. According to the pattern, the increase of the load intensity (damage factor m=Ph/Pul involves an increase in the damage of the continuity, or the rebuff ability of the soil foundation.
Effect of torsional loading on compressive fatigue behaviour of trabecular bone.
Fatihhi, S J; Rabiatul, A A R; Harun, M N; Kadir, Mohammed Rafiq Abdul; Kamarul, T; Syahrom, Ardiyansyah
2016-02-01
The present study reports the effects of combined torsional and compressive cyclic loading on trabecular bone in order to mimic true physiological conditions and thereby provides improved data that represents clinical and real life conditions. However, only compressive behaviour is evaluated in most previous studies of bone mechanics. From the monotonic evaluation, it is observed that lower stress is needed for the onset of microcrack in the sample under torsional loading, compared to the stress needed in compression. Trabecular bone samples were subjected to a combination of torsion and compression fatigue at different stress levels during which they were compared to compressive axial fatigue. The stress levels were determined by considering the monotonic strength at 25-50% for both compressive and shear stresses. Significant decrease in fatigue lifetime is observed in between samples of pure compression fatigue and those with superpositioned torsional loading (ptorsional stress level. In this case, the failure of the sample is said to be 'torsional dominant'. Fatigue behaviour of bovine trabecular bone begins with plastic deformation, followed by strain accumulation and modulus reduction. As the strain rate increases, more energy dissipates and the sample finally failed. Further, the analysis of fractograph revealed something on the trabeculae by bending in sample with superpositioned torsional loading. In conclusion, torsional loading decreases the quality of the trabecular properties in terms of stiffness, life and structural integrity. It is hoped that results from this study will improve the understanding of the behaviour of trabecular bone under combined fatigue and help to develop future assessments of trabecular failure. Copyright © 2015 Elsevier Ltd. All rights reserved.
Comparison of Numerical Analyses with a Static Load Test of a Continuous Flight Auger Pile
Hoľko, Michal; Stacho, Jakub
2014-12-01
The article deals with numerical analyses of a Continuous Flight Auger (CFA) pile. The analyses include a comparison of calculated and measured load-settlement curves as well as a comparison of the load distribution over a pile's length. The numerical analyses were executed using two types of software, i.e., Ansys and Plaxis, which are based on FEM calculations. Both types of software are different from each other in the way they create numerical models, model the interface between the pile and soil, and use constitutive material models. The analyses have been prepared in the form of a parametric study, where the method of modelling the interface and the material models of the soil are compared and analysed. Our analyses show that both types of software permit the modelling of pile foundations. The Plaxis software uses advanced material models as well as the modelling of the impact of groundwater or overconsolidation. The load-settlement curve calculated using Plaxis is equal to the results of a static load test with a more than 95 % degree of accuracy. In comparison, the load-settlement curve calculated using Ansys allows for the obtaining of only an approximate estimate, but the software allows for the common modelling of large structure systems together with a foundation system.
Comparison of Numerical Analyses with a Static Load Test of a Continuous Flight Auger Pile
Directory of Open Access Journals (Sweden)
Hoľko Michal
2014-12-01
Full Text Available The article deals with numerical analyses of a Continuous Flight Auger (CFA pile. The analyses include a comparison of calculated and measured load-settlement curves as well as a comparison of the load distribution over a pile's length. The numerical analyses were executed using two types of software, i.e., Ansys and Plaxis, which are based on FEM calculations. Both types of software are different from each other in the way they create numerical models, model the interface between the pile and soil, and use constitutive material models. The analyses have been prepared in the form of a parametric study, where the method of modelling the interface and the material models of the soil are compared and analysed.
Comparison of Design Methods for Axially Loaded Driven Piles in Cohesionless Soil
DEFF Research Database (Denmark)
Thomassen, Kristina; Andersen, Lars Vabbersgaard; Ibsen, Lars Bo
2012-01-01
For offshore wind turbines on deeper waters, a jacket sub-structure supported by axially loaded piles is thought to be the most suitable solution. The design method recommended by API and two CPT-based design methods are compared for two uniform sand profiles. The analysis show great difference...
Evaluation of the Load-Displacement Relationships for Large-Diameter Piles in Sand
DEFF Research Database (Denmark)
Sørensen, Søren Peder Hyldal; Brodbaek, K. T.; Moller, M.
2009-01-01
For laterally loaded piles in sand with diameters up to 6 m, e.g. monopiles used as foundations for offshore wind turbines, there is no approved design procedure. The p-y curve method, given in offshore design regulations, is usually employed for the design of monopiles. However, this method was ...
Improved Design Basis for Laterally Loaded Large Diameter Pile
DEFF Research Database (Denmark)
Leth, Caspar Thrane
The development of offshore wind turbines has been in rapid growth since the construction of the first offshore wind farm in 1991 at Vindeby, Denmark. Developing from 11 turbines at a water depth of 2-6 m each with a capacity of 450 kW to the latest farms with up to 175 turbines each with a capac......The development of offshore wind turbines has been in rapid growth since the construction of the first offshore wind farm in 1991 at Vindeby, Denmark. Developing from 11 turbines at a water depth of 2-6 m each with a capacity of 450 kW to the latest farms with up to 175 turbines each...... with a capacity of 3.6 MW and placed at water depths beyond 25 m. Different foundation solutions have over the years been applied for offshore turbines, but monopiles are currently the most applied foundation type and are typically with a pile diameter of 4-6 m and applied up to a water depth of 25 m....... The expected development of offshore wind farms is towards larger farms, larger turbines and larger water depths. Monopiles have been applied widely and it is of interest to investigate the possibilities to further optimize the design and in particular the modelling of the soil-structure interaction...
Motevalli, B.; Montazeri, A.; Tavakoli-Darestani, R.; Rafii-Tabar, H.
2012-09-01
A number of studies have been performed on the mechanical and deformational properties of carbon nanotubes under different loading conditions, such as compression, tension, torsion, bending, and hydrostatic pressure. However, in practical applications, such as in nanotube-reinforced nanocomposites, these different loading conditions are present simultaneously. We employ molecular dynamics simulation to compute the behavior and deformation properties of carbon nanotubes under combined application of compression and torsion. The buckling properties and the corresponding mode shapes are investigated, for the first time, for different rotational and axial displacement rates. It is found that the critical loads and the buckling deformations strongly depend upon the ratio of these displacement rates. Finally, a relationship between the shear and normal stresses is established, which can be used for determining the stress limits when designing practical carbon nanotube-based systems in which combined loads may be applied.
Dynamic response of a clamped/free hollow circular cylinder under travelling torsional impact loads
International Nuclear Information System (INIS)
Jonker, J.B.
1982-01-01
Impact-induced vibrations in the casing of a gas centriguge due to a sudden failure of the spinning rotor (crash) can cause structural disintegrity of the casing. In order to study the influence of the rotor failure bahaviour and the impact load histories on the dynamic response of the casing, a simple crash model is proposed in this paper to analyse the transient torsional response due to tangential components of the impact loads. The casing is modeled as a linear-elastic hollow circular cylinder, clamped at the lower end and free at the upper end. The rotor is thought to breakup in identical sections in a sequence determined by its fracture behaviour. Each section is assumed to cause an axi-symmetric load distribution at the inner surface of the casing. Therefore the problem is essentially reduced to the analysis of a clamped/free cylinder under travelling torsional impact loads. The problem is solved by representing the impact loads as local pulses acting over the length of the sections. A perturbation method is used to show that the general two-dimensional theory of axi-symmetric torsional wave propagation in circular cylinders, for the problem under consideration, may be approximated by the elementary one-dimensional theory. Solutions are obtained according to the usual modal expansion approach. Measurements of transient torsional responses are shown to be in good agreement with the calculated responses by choosing a suitable shape of the pulses. The effects of travelling velocity and pulse shape are investigated. Finally the transfer of kinetic energy in the rotor to vibrational energy of torsion in the casing is studied. (orig.)
Laboratory Test Setup for Cyclic Axially Loaded Piles in Sand
DEFF Research Database (Denmark)
Thomassen, Kristina; Ibsen, Lars Bo; Andersen, Lars Vabbersgaard
2017-01-01
conditions for all tests. For verifications purposes six static tension tests conducted at three different vertical effective stress levels of 0, 35 and 70 kPa. The load-displacement curves showed that the test setup provides repeatable test results. A preliminary comparison between the unit shaft friction...
Assem, Yusuf; Pelletier, Matthew H; Mobbs, Ralph J; Phan, Kevin; Walsh, William R
2017-05-01
To perform a repeatable idealized in vitro model to evaluate the effects of key design features and integrated screw fixation on unloaded surface engagement, subsidence, and torsional stability. We evaluated four different stand-alone anterior lumbar interbody fusion (ALIF) cages with two, three, and four screw designs. Polyurethane (saw-bone) foam blocks were used to simulate the vertebral bone. Fuji Film was used to measure the contact footprint, average pressure, and load generated by fixating the cages with screws. Subsidence was tested by axially loading the constructs at 10 N/s to 400 N and torsional load was applied +/-1 Nm for 10 cycles to assess stability. Outcome measures included total subsidence and maximal torsional angle range. Cages 1, 2, and 4 were symmetrical and produced similar results in terms of contact footprint, average pressure, and load. The addition of integrated screws into the cage-bone block construct demonstrated a clear trend towards decreased subsidence. Cage 2 with surface titanium angled ridges and a keel produced the greatest subsidence with and without screws, significantly more than all other cages ( P < 0.05). Angular rotation was not significantly affected by the addition of screws ( P < 0.066). A statistically significant correlation existed between subsidence and reduced angular rotation across all cage constructs ( P = 0.018). Each stand-alone cage featured unique surface characteristics, which resulted in differing cage-foam interface engagement, influencing the subsidence and torsional angle. Increased subsidence significantly reduced the torsional angle across all cage constructs. © 2017 Chinese Orthopaedic Association and John Wiley & Sons Australia, Ltd.
Ratcheting of 316L stainless steel thin wire under tension-torsion loading
Directory of Open Access Journals (Sweden)
Sichao Fu
2016-10-01
Full Text Available A series of cyclic tension-torsion tests under symmetric shear strain and asymmetric axial stress control in various loading paths are conducted on 100 μm-diameter 316L steel wires applying a micro tensiontorsion fatigue testing apparatus. The ratcheting strain of the thin wire increases with increasing axial mean stress and decreases in a sequence of linear, rhombic and circular paths. The macro-scale based cyclic plastic constitutive models with kinematic hardening rules of the Ohno-Wang (OW and the Chen-Jiao-Kim (C-J-K are evaluated for the thin wire. Comparing with the O-W, the C-J-K predicts more accurately under high axial stress. While the loading path effects on ratcheting for wire specimens are basically simulated, the macro-based models tend to under-estimate the effect of phase difference between axial and torsional loadings and the ratcheting evolution in the initial 50 cycles
Centrifuge modelling of large diameter pile in sand subject to lateral loading
DEFF Research Database (Denmark)
Leth, Caspar Thrane
and cyclic behaviour of large diameter rigid piles in dry sand by use of physical modelling. The physical modelling has been carried out at Department of Civil Engineering at the Danish Technical University (DTU.BYG), in the period from 2005 to 2009. The main centrifuge facilities, and especially...... the equipment for lateral load tests were at the start of the research in 2005 outdated and a major part of the work with the geotechnical centrifuge included renovation and upgrading of the facilities. The research with respect to testing of large diameter piles included: Construction of equipment...... with embedment lengths of 6, 8 and 10 times the diameter. The tests have been carried out with a load eccentricity of 2.5 m to 6.5 m above the sand surface. The present report includes a description of the centrifuge facilities, applied test procedure and equipment along with presentation of the obtained results....
Study on load-bearing characteristics of a new pile group foundation for an offshore wind turbine.
Lang, Ruiqing; Liu, Run; Lian, Jijian; Ding, Hongyan
2014-01-01
Because offshore wind turbines are high-rise structures, they transfer large horizontal loads and moments to their foundations. One of the keys to designing a foundation is determining the sensitivities and laws affecting its load-bearing capacity. In this study, this procedure was carried out for a new high-rise cap pile group foundation adapted to the loading characteristics of offshore wind turbines. The sensitivities of influential factors affecting the bearing properties were determined using an orthogonal test. Through a combination of numerical simulations and model tests, the effects of the inclination angle, length, diameter, and number of side piles on the vertical bearing capacity, horizontal bearing capacity, and bending bearing capacity were determined. The results indicate that an increase in the inclination angle of the side piles will increase the vertical bearing capacity, horizontal bearing capacity, and bending bearing capacity. An increase in the length of the side piles will increase the vertical bearing capacity and bending bearing capacity. When the length of the side piles is close to the central pile, the increase is more apparent. Finally, increasing the number of piles will increase the horizontal bearing capacity; however, the growth rate is small because of the pile group effect.
Study on Load-Bearing Characteristics of a New Pile Group Foundation for an Offshore Wind Turbine
Liu, Run; Lian, Jijian; Ding, Hongyan
2014-01-01
Because offshore wind turbines are high-rise structures, they transfer large horizontal loads and moments to their foundations. One of the keys to designing a foundation is determining the sensitivities and laws affecting its load-bearing capacity. In this study, this procedure was carried out for a new high-rise cap pile group foundation adapted to the loading characteristics of offshore wind turbines. The sensitivities of influential factors affecting the bearing properties were determined using an orthogonal test. Through a combination of numerical simulations and model tests, the effects of the inclination angle, length, diameter, and number of side piles on the vertical bearing capacity, horizontal bearing capacity, and bending bearing capacity were determined. The results indicate that an increase in the inclination angle of the side piles will increase the vertical bearing capacity, horizontal bearing capacity, and bending bearing capacity. An increase in the length of the side piles will increase the vertical bearing capacity and bending bearing capacity. When the length of the side piles is close to the central pile, the increase is more apparent. Finally, increasing the number of piles will increase the horizontal bearing capacity; however, the growth rate is small because of the pile group effect. PMID:25250375
Directory of Open Access Journals (Sweden)
Ibrahim H. Abu-Tahun
2018-01-01
Full Text Available This study compared the microscopic features of the fractured endodontic nickel-titanium (NiTi rotary instruments by two different torsional loadings: repetitive torsional loading (RTL and single torsional loading (STL based on the International Organization for Standardization (ISO. ProTaper Next, HyFlex EDM, and V-Taper 2 were compared in this study. In the STL method, the torsional load was applied after fixing the 3 mm tip of the file, by continuous clockwise rotation (2 rpm until fracture. In the RTL method, a preset rotational loading (0.5 N·cm was applied and the clockwise loading to the preset torque and counterclockwise unloading to original position were repeated at 50 rpm until the file fractured. Fractured fragments by two methods were compared under a scanning electron microscope (SEM to examine the topographic features of the fractured surfaces and longitudinal aspects. SEM examinations showed significantly different features according to the loading methods. Specimens from the RTL method showed ruptured aspects on cross sections, with multiple areas of initiated cracks while the STL method showed the typical features of torsional failure, such as circular abrasion marks and fatigue dimples. This study suggested a new repetitive torsional loading method which is much more clinically relevant and may result in a different fracture feature from STL method.
Ahmadi, Habiburrahman
Thin-walled structures are major components in many engineering applications. When a thin-walled slender beam is subjected to lateral loads, causing moments, the beam may buckle by a combined lateral bending and twisting of cross-section, which is called lateral-torsional buckling. A generalized analytical approach for lateral-torsional buckling of anisotropic laminated, thin-walled, rectangular cross-section composite beams under various loading conditions (namely, pure bending and concentrated load) and boundary conditions (namely, simply supported and cantilever) was developed using the classical laminated plate theory (CLPT), with all considered assumptions, as a basis for the constitutive equations. Buckling of such type of members has not been addressed in the literature. Closed form buckling expressions were derived in terms of the lateral, torsional and coupling stiffness coefficients of the overall composite. These coefficients were obtained through dimensional reduction by static condensation of the 6x6 constitutive matrix mapped into an effective 2x2 coupled weak axis bending-twisting relationship. The stability of the beam under different geometric and material parameters, like length/height ratio, ply thickness, and ply orientation, was investigated. The analytical formulas were verified against finite element buckling solutions using ABAQUS for different lamination orientations showing excellent accuracy.
Numerical analysis of two pile caps with sockets embedded, subject the eccentric compression load
Directory of Open Access Journals (Sweden)
R. G. Delalibera
Full Text Available The structural behavior of pile caps with sockets embedded is influenced by interface of column-socket, which can be smooth or rough. With intent to analyze the behavior of two pile caps with embedded socket, considering the friction between the column and the socket, with eccentric normal load, the numerical simulations were carried out, using a program based on the Finite Element Methods (FEM. In the numerical analysis the non-linear behavior of materials was considered, also the friction between the column and the socket. It was considered perfect bond between the reinforcement and the concrete around. It was observed that the embedded length is preponderant factor in the structural behavior of the analyzed element.
Ai, Zhi Yong; Li, Zhi Xiong; Wang, Li Hua
2016-12-01
The time-harmonic response of a laterally loaded fixed-head pile group embedded in a transversely isotropic multilayered half-space is investigated using a finite element and indirect boundary element coupling method. The piles are solved by the finite element method (FEM), while the soil can be modeled by the indirect boundary element method (BEM) with the aid of the fundamental solution for a transversely isotropic multilayered half-space in a cylindrical coordinate system. The governing equation of the pile-soil-pile dynamic interaction is established by applying the FEM-BEM coupling method. Numerical examples are carried out to validate the presented theory and to investigate influences of the soil's anisotropy and layering on the dynamic response of pile groups.
Direct Design of T-Beams for Combined Load of Bending and Torsion
Directory of Open Access Journals (Sweden)
A. S. Alnuaimi
2007-12-01
Full Text Available Tests were conducted on five reinforced concrete T-beams subjected to combined load of bending and torsion. Elastic stress field in conjunction with Nielsen's 2D yield criterion for reinforced concrete subjected to in-plane forces were used in the Direct Design Method for the design of reinforcement. The beam dimensions were: flange width = 600mm, flange thickness = 150mm, web width = 200mm, total depth = 600mm and beam length = 5.2m. Required reinforcement calculated using the Direct Design Method was compared with the ACI and BSI codes. It was found that the Direct Design Method requires longitudinal reinforcement similar to the ACI code but less than the BSI code. In the transverse direction, the Direct Design Method requires much less reinforcement than both codes. The main variable studied was the ratio of the maximum twisting moment to the bending moment which was varied between 0.6 and 1.5. Good agreement was found between the design and experimental failure loads. Most of the longitudinal and transverse steel yielded or reached near yield stress when the design load was approached. All beams failed near the design loads and undergone ductile behaviour until failure. The results indicate that the Direct Design Method can be successfully used to design reinforced concrete T-beams for the combined effect of bending and torsion loads.
Directory of Open Access Journals (Sweden)
Ricardo A. da Mota Silveira
Full Text Available AbstractThis paper presents a nonlinear stability analysis of piles under bilateral contact constraints imposed by a geological medium (soil or rock. To solve this contact problem, the paper proposes a general numerical methodology, based on the finite element method (FEM. In this context, a geometrically nonlinear beam-column element is used to model the pile while the geological medium can be idealized as discrete (spring or continuum (Winkler and Pasternak foundation elements. Foundation elements are supposed to react under tension and compression, so during the deformation process the structural elements are subjected to bilateral contact constraints. The errors along the equilibrium paths are minimized and the convoluted nonlinear equilibrium paths are made traceable through the use of an updated Lagrangian formulation and a Newton-Raphson scheme working with the generalized displacement technique. The study offers stability analyses of three problems involving piles under bilateral contact constraints. The analyses show that in the evaluation of critical loads a great influence is wielded by the instability modes. Also, the structural system stiffness can be highly influenced by the representative model of the soil.
Gosnell, W Casey; Butcher, Michael T; Maie, Takashi; Blob, Richard W
2011-10-15
Studies of limb bone loading in terrestrial mammals have typically found anteroposterior bending to be the primary loading regime, with torsion contributing minimally. However, previous studies have focused on large, cursorial eutherian species in which the limbs are held essentially upright. Recent in vivo strain data from the Virginia opossum (Didelphis virginiana), a marsupial that uses a crouched rather than an upright limb posture, have indicated that its femur experiences appreciable torsion during locomotion as well as strong mediolateral bending. The elevated femoral torsion and strong mediolateral bending observed in D. virginiana might result from external forces such as a medial inclination of the ground reaction force (GRF), internal forces deriving from a crouched limb posture, or a combination of these factors. To evaluate the mechanism underlying the loading regime of opossum femora, we filmed D. virginiana running over a force platform, allowing us to measure the magnitude of the GRF and its three-dimensional orientation relative to the limb, facilitating estimates of limb bone stresses. This three-dimensional analysis also allows evaluations of muscular forces, particularly those of hip adductor muscles, in the appropriate anatomical plane to a greater degree than previous two-dimensional analyses. At peak GRF and stress magnitudes, the GRF is oriented nearly vertically, inducing a strong abductor moment at the hip that is countered by adductor muscles on the medial aspect of the femur that place this surface in compression and induce mediolateral bending, corroborating and explaining loading patterns that were identified in strain analyses. The crouched orientation of the femur during stance in opossums also contributes to levels of femoral torsion as high as those seen in many reptilian taxa. Femoral safety factors were as high as those of non-avian reptiles and greater than those of upright, cursorial mammals, primarily because the load
Torsional Buckling of I Beam and Flat Bar Stiffeners under Combined Lateral and Axial Loading.
1985-06-01
Development of the Virtual Work Equation ......... 20 2.3 Determination of the Critical Buckling Load ...... 23 3. Model II - Torsional Buckling Under... Virtual Work Equation Work is defined as the movement of a force through a distance. ," In the case of Model I then the virtual work done is obtained by...1- sin 2 a dx 4EI a which when integrated becomes: 22 2 P~o+ 67T 2 Bo7r aa + GJ(-) - 4EI 192, a 4 z 28 .. 3.2 Development of the Virtual Work Equation
Lager, J. R.
1975-01-01
A cylindrical shell structure 3.66 m (144 in.) high by 4.57 m (180 in.) diameter was designed using a wide variety of materials and structural concepts to withstand design ultimate combined loading 1225.8 N/cm (700 lb/in.) axial compression and 245.2 N/cm (140 lb/in.) torsion. The overall cylinder geometry and design loading are representative of that expected on a high performance space tug vehicle. The relatively low design load level results in designs that use thin gage metals and fibrous-composite laminates. Fabrication and structural tests of small panels and components representative of many of the candidate designs served to demonstrate proposed fabrication techniques and to verify design and analysis methods. Three of the designs evaluated, honeycomb sandwich with aluminum faceskins, honeycomb sandwich with graphite/epoxy faceskins, and aluminum truss with fiber-glass meteoroid protection layers, were selected for further evaluation.
A zero torsional stiffness twist morphing blade as a wind turbine load alleviation device
International Nuclear Information System (INIS)
Lachenal, X; Daynes, S; Weaver, P M
2013-01-01
This paper presents the design, analysis and realization of a zero stiffness twist morphing wind turbine blade. The morphing blade is designed to actively twist as a means of alleviating the gust loads which reduce the fatigue life of wind turbine blades. The morphing structure exploits an elastic strain energy balance within the blade to enable large twisting deformations with modest actuation requirements. While twist is introduced using the warping of the blade skin, internal pre-stressed members ensure that a constant strain energy balance is achieved throughout the deformation, resulting in a zero torsional stiffness structure. The torsional stability of the morphing blade is characterized by analysing the elastic strain energy in the device. Analytical models of the skin, the pre-stressed components and the complete blade are compared to their respective finite element models as well as experimental results. The load alleviation potential of the adaptive structure is quantified using a two-dimensional steady flow aerodynamic model which is experimentally validated with wind tunnel measurements. (paper)
2017-01-30
will lose moment capacity there as well. Soil -Structure Interaction (SSI) software will be needed to determine the load that causes a moment failure...Cohesionless Soils to Withstand Lateral Barge Train Impact Loads In fo rm at io n an d Te ch no lo gy L ab or at or y Barry C. White and...Pile Depth of Embedment in Cohesionless Soils to Withstand Lateral Barge Train Impact Loads Barry C. White and Robert M. Ebeling Information
Katsuta, Yasuhiro; Watanabe, Fumihiko
2015-01-01
Cyclic torsional loading tests were carried out in the laboratory using various implant systems, in order to clarify differences between the systems in loosening of abutment screws. Six samples from six commercially available abutment systems were used, giving a total of 36 samples. Four of the systems used internal connections, and two used external connections. The abutment screw for each system was tightened to a torque value specified by the manufacturer, and after 5 min, the loosening torque was measured using a digital torque meter. Measurements were taken twice, and a second measurement was taken as a reference value. A cyclic torsional loading test with 100,000 cycles was performed on the sample, and the loosening torque was again measured after the test. In conclusion, loosening of the abutment screw occurred as a result of cyclic torsional loading, and the degree of loosening varied with each implant system.
Load and resistance factor design of bridge foundations accounting for pile group-soil interaction.
2015-11-01
Pile group foundations are used in most foundation solutions for transportation structures. Rigorous and reliable pile design methods are : required to produce designs whose level of safety (probability of failure) is known. By utilizing recently dev...
The response of pile-guided floats subjected to dynamic loading : volume I final report.
2014-08-01
Pile : - : Guided floats can be a desirable alternative to stationary berthing structures. Both floats and guide piles are subjected to dynamic : forces such as wind generated waves and impacts from vessels. This project developed a rational basis fo...
Simple criterion for predicting fatigue life under combined bending and torsion loading
Directory of Open Access Journals (Sweden)
K. Slámečka
2017-07-01
Full Text Available Multiaxial fatigue is a challenging problem and, consequently, a number of methods has been developed to aid in design of components and assemblies. Following the complexity of the problem, these approaches are often elaborate and it is difficult to use them for simple loading cases. In this paper, an empirical approach for constant amplitude, proportional axial and torsion loading is introduced to serve as a basic engineering tool for estimating fatigue life of rotational structural parts. The criterion relies on a quadratic equivalent-stress formula and requires one constant parameter to be determined from experiments. The comparison with similar classical stressbased approaches using data on diverse materials (several steels, aluminium alloy, and nickel base superalloy reveals very good agreement with experimental data.
EFFECTIVNESS OF THE FATIGUE CRITERIA FOR COMBINED BENDING – TORSION LOADING
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Štěpán Major
2010-12-01
Full Text Available Most of mechanical components in the engineering are frequently subjected to combined loading, which can lead to sudden fatigue failure. In present work the fatigue life of plasma-nitrided and virgin specimens is studied. Specimens made of low-alloy high-strength steel. Specimens were subjected to an in-phase combined bending-torsion loading. The plasma-nitrided specimens have significantly improved fatigue resistance. The most relevant goal of this paper is to verify the efficiency of classical and advanced stress based multiaxial criteria. The criterion proposed by McDiarmid was found to be the most precise in the fatigue life prediction for virgin specimens. On the other hand, the Matake criterion was the most successful for nitrided specimens.
3D Numerical Analysis of the Effects of an Advancing Tunnel on an Existing Loaded Pile Group
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M. A. Soomro
2018-02-01
Full Text Available Tunnels are often preferred for underground transportation in densely populated areas. In these areas, it is almost inevitable for tunnels to run close to some existing pile foundations. Since tunnelling activities induce stress relief and soil movement in the ground, existing piles may suffer from additional axial and lateral forces, bending moments, settlements and lateral deflections. Most of the previous researches on the responses of pile foundations due to tunnel construction were carried out under the plane strain condition. In this paper, a three-dimensional, elasto-plastic and coupled-consolidation finite element parametric study has been carried out to investigate the effects of a 6 m open-face advancing tunnel on a two by two pile group in saturated stiff clay. The influence of different cover-to-diameter (C/D tunnel ratios (namely 2.0, 2.5 & 3.0 was studied. The objectives of this study are to determine the changes in axial load distribution, changes in shaft resistance along the shaft of pile group and settlement of pile cap due to an advancing open-face tunnel.
Morris C. Johnson; Jessica E. Halofsky; David L. Peterson
2013-01-01
We used a combination of field measurements and simulation modelling to quantify the effects of salvage logging, and a combination of salvage logging and pile-and-burn fuel surface fuel treatment (treatment combination), on fuel loadings, fire behaviour, fuel consumption and pollutant emissions at three points in time: post-windstorm (before salvage logging), post-...
Ilin, K.; Ilin, K.; Yagotyntsev, Kostyantyn; Zhou, Chao; Gao, Peng; Kosse, Jaap Jeroen; Otten, S.J.; Wessel, Wilhelm A.J.; Haugan, T.J.; van der Laan, D.C.; Nijhuis, Arend
2015-01-01
For high current superconductors in high magnet fields with currents in the order of 50 kA, single ReBCO coated conductors must be assembled in a cable. The geometry of such a cable is mostly such that combined torsion, axial and transverse loading states are anticipated in the tapes and tape
Homminga, Jasper Johan; Lehr, A.M.; Meijer, Gerdine; Janssen, M.M.A.; Schlösser, T.P.C.; Verkerke, Gijsbertus Jacob; Castelein, R.M.
2013-01-01
Objective. To analyze the effects of posterior shear loads, disc degeneration, and the combination of both on spinal torsion stiffness. Summary of Background Data. Scoliosis is a 3-dimensional deformity of the spine that presents itself mainly in adolescent girls and elderly patients. Our concept of
Sumanth, D.; Preetish, K. L.; Srinivasan, S. M.
2014-08-01
Given that most applications of shape memory alloys (SMA) are in the wire form, a reduced order model and analysis has been attempted in this paper. It takes into account the fact that the predominant actions are axial (bending inclusive) and torsional. A thermodynamic framework is first developed to simulate the behaviour of the SMA material under thermo-mechanical loading that is a combination of axial and shear stresses arising at a point in a wire due to axial and torsional loads applied to the wire. Since only a few variants relevant to axial-torsion are going to be active in transformation under this kind of loading, a reduced order model that tracks the evolution of four martensite variants and an austenite variant is proposed. It is shown through simulations that these five model parameters amply form a minimal set of model parameters sufficient for simulating response under tension-torsion loading excursions. The model is further applied to the structural member, in this case, a wire of circular cross-section subject to a twist and an axial extension and the capability of the model to simulate the kind of response expected in wires. Incorporation of this model into a large deformation space frame nonlinear analysis will help in the design and analysis of several applications where SMA wire forms are used.
International Nuclear Information System (INIS)
Sumanth, D; Preetish, K L; Srinivasan, S M
2014-01-01
Given that most applications of shape memory alloys (SMA) are in the wire form, a reduced order model and analysis has been attempted in this paper. It takes into account the fact that the predominant actions are axial (bending inclusive) and torsional. A thermodynamic framework is first developed to simulate the behaviour of the SMA material under thermo-mechanical loading that is a combination of axial and shear stresses arising at a point in a wire due to axial and torsional loads applied to the wire. Since only a few variants relevant to axial-torsion are going to be active in transformation under this kind of loading, a reduced order model that tracks the evolution of four martensite variants and an austenite variant is proposed. It is shown through simulations that these five model parameters amply form a minimal set of model parameters sufficient for simulating response under tension–torsion loading excursions. The model is further applied to the structural member, in this case, a wire of circular cross-section subject to a twist and an axial extension and the capability of the model to simulate the kind of response expected in wires. Incorporation of this model into a large deformation space frame nonlinear analysis will help in the design and analysis of several applications where SMA wire forms are used. (paper)
Matsuda, Tatsuya; Miura, Kinya; Sawada, Yayoi
2017-10-01
This study investigated the characteristics of wave forces loading on the detached structure that consisted of an upper structure and a pile foundation. In this study, structure stability was also considered on the results obtained from previous studies on the instability of seabed induced by wave force. When a wave force acted on the structure, an external force acted on the pile foundation as if pulling out the foundation on the outer harbor side and pushing it in on the inner harbor. The effective stress in seabed was increase so the pile foundation was considered to maintain sufficient bearing capacity. Subsequently, when the bearing capacity of the ground was decreased because the water pressure in the ground surface layer decreased, the pile foundation will be aggravated settled down. The external force acting on the pile foundation was not same on outer harbor and inner harbor with the form of the upper structure. As a result, we found that the strain will be generated on the structure.
Pile Driving Analysis for Pile Design and Quality Assurance
2017-08-01
Driven piles are commonly used in foundation engineering. The most accurate measurement of pile capacity is achieved from measurements made during static load tests. Static load tests, however, may be too expensive for certain projects. In these case...
Concrete Open-Wall Systems Wrapped with FRP under Torsional Loads
Directory of Open Access Journals (Sweden)
Valentino P. Berardi
2012-10-01
Full Text Available The static behavior of reinforced concrete (RC beams plated with layers of fiber-reinforced composite material (FRP is widely investigated in current literature, which deals with both its numerical modeling as well as experiments. Scientific interest in this topic is explained by the increasing widespread use of composite materials in retrofitting techniques, as well as the consolidation and upgrading of existing reinforced concrete elements to new service conditions. The effectiveness of these techniques is typically influenced by the debonding of the FRP at the interface with concrete, where the transfer of stresses occurs from one element (RC member to the other (FRP strengthening. In fact, the activation of the well-known premature failure modes can be regarded as a consequence of high peak values of the interfacial interactions. Until now, typical applications of FRP structural plating have included cases of flexural or shear-flexural strengthening. Within this context, the present study aims at extending the investigation to the case of wall-systems with open cross-section under torsional loads. It includes the results of some numerical analyses carried out by means of a finite element approximation.
Directory of Open Access Journals (Sweden)
Mir Tahmaseb Kashani
2015-01-01
Full Text Available The dynamic analysis of prestressed, bending-torsion coupled beams is revisited. The axially loaded beam is assumed to be slender, isotropic, homogeneous, and linearly elastic, exhibiting coupled flexural-torsional displacement caused by the end moment. Based on the Euler-Bernoulli bending and St. Venant torsion beam theories, the vibration and stability of such beams are explored. Using the closed-form solutions of the uncoupled portions of the governing equations as the basis functions of approximation space, the dynamic, frequency-dependent, interpolation functions are developed, which are then used in conjunction with the weighted residual method to develop the Dynamic Finite Element (DFE of the system. Having implemented the DFE in a MATLAB-based code, the resulting nonlinear eigenvalue problem is then solved to determine the coupled natural frequencies of illustrative beam examples, subjected to various boundary and load conditions. The proposed method is validated against limited available experimental and analytical data, those obtained from an in-house conventional Finite Element Method (FEM code and FEM-based commercial software (ANSYS. In comparison with FEM, the DFE exhibits higher convergence rates and in the absence of end moment it produces exact results. Buckling analysis is also carried out to determine the critical end moment and compressive force for various load combinations.
Effect of torsional loading of nickel-titanium instruments on cyclic fatigue resistance.
Cheung, Gary Shun-Pan; Oh, Seung-Hei; Ha, Jung-Hong; Kim, Sung Kyo; Park, Se-Hee; Kim, Hyeon-Cheol
2013-12-01
The aim of this study was to evaluate the effect of torsional preload on the cyclic fatigue life of nickel-titanium rotary instruments. ProFile (#25/0.06) (Dentsply Maillefer, Ballaigues, Switzerland) and ProTaper (F1; Dentsply Maillefer) were used. Each file was preloaded at 4 conditions (ie, no preloading and 25%, 50%, and 75% of mean ultimate torsional strength) of torsional prestress before the fatigue test. The torsional preloads were applied by securing 5 mm of the file tip while keeping the file straight, rotating it clockwise until the preset torque, and then returning to the original position. This motion was repeated until a preset number (10, 30, or 50) of repetitions were reached (n = 12). After torsional preloading, the number of cycles to failure was evaluated in a simulated canal. Data were analyzed using 2-way analysis of variance and the Duncan post hoc comparison. The fractured fragment surfaces were examined under a scanning electron microscope for the topographic features of fractured instruments. For both instruments, there was a significant effect because of the extent of torsional preloads. The 50% and 75% torsionally preloaded ProFile and all ProTaper preloading groups had a higher number of cycles to failure than the other group(s). There was little difference in the lateral view appearance between new and torsionally preloaded files. After cyclic fatigue testing, all preloaded instruments showed numerous microcracks adjacent to the fracture site on lateral view examination. The microcracks did not seem to follow the machining grooves on the instrument surface but rather ran irregularly. The torsional preloads within the superelastic limit of the material may improve the cyclic fatigue resistance of nickel-titanium rotary instruments. Copyright © 2013 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.
Ilin, K.; Yagotintsev, K. A.; Zhou, C.; Gao, P.; Kosse, J.; Otten, S. J.; Wessel, W. A. J.; Haugan, T. J.; van der Laan, D. C.; Nijhuis, A.
2015-05-01
For high current superconductors in high magnet fields with currents in the order of 50 kA, single ReBCO coated conductors must be assembled in a cable. The geometry of such a cable is mostly such that combined torsion, axial and transverse loading states are anticipated in the tapes and tape joints. The resulting strain distribution, caused by different thermal contraction and electromagnetic forces, will affect the critical current of the tapes. Tape performance when subjected to torsion, tensile and transverse loading is the key to understanding limitations for the composite cable performance. The individual tape material components can be deformed, not only elastically but also plastically under these loads. A set of experimental setups, as well as a convenient and accurate method of stress-strain state modeling based on the finite element method have been developed. Systematic measurements on single ReBCO tapes are carried out combining axial tension and torsion as well as transverse loading. Then the behavior of a single tape subjected to the various applied loads is simulated in the model. This paper presents the results of experimental tests and detailed FE modeling of the 3D stress-strain state in a single ReBCO tape under different loads, taking into account the temperature dependence and the elastic-plastic properties of the tape materials, starting from the initial tape processing conditions during its manufacture up to magnet operating conditions. Furthermore a comparison of the simulations with experiments is presented with special attention for the critical force, the threshold where the tape performance becomes irreversibly degraded. We verified the influence of tape surface profile non-uniformity and copper stabilizer thickness on the critical force. The FE models appear to describe the tape experiments adequately and can thus be used as a solid basis for optimization of various cabling concepts.
Stress Relaxation Of Superelastic Shape Memory Alloy Under Bending And Torsional Load
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Sakib Tanvir
2017-04-01
Full Text Available Stress Relaxation of Superelastic Shape memory NiTi Alloy under bending and torsion is uncommon in literature. Therefore experimental set up has been devised and test results are obtained for superelastic SMA.Unlike the other common engineering materials superelastic SMA it gives dramatic reduction in stress. In this paper therefore results of stress relaxation of superelastic shape memory alloy under bending and torsion are presented graphically and interpreted in terms of stress induced martensitic transformation.
Directory of Open Access Journals (Sweden)
Saeed Ghaffarpour Jahromi
2015-12-01
Full Text Available The goal of this research is to study the effect of the space between long and short piles beneath combined deep foundation caps on the forces acting on piles and the resulting summit, all done by considering variables such as; short pile length, soil pad stiffness (cushion, short pile stiffness and long pile stiffness, using a modeling and numerical analysis method. Modeling and numerical analysis are performed using the Abacus software, which results indicated that by increasing the space between short and long piles, the compressive axial tension acting on short piles rises and the compressive axial tension acting on long piles almost reduces, and also increasing the space between short and long piles will reduce the resulting summit and by rising the elastic modulus of short piles the summit reduces and increasing the elastic modulus of long and short piles results in reducing the summit.
2013-04-01
Damage in pile supported structures due to liquefaction and liquefaction induced deformation were reported in past earthquakes around the world (eg, Ansal et al. 1999, Seed et al. 1990, EERI 2010, EERI 2011, GEER 2010a, GEER 2010b, GEER 2011). For ex...
Assessment of Calculation Procedures for Piles in Clay Based on Static Loading Tests
DEFF Research Database (Denmark)
Augustesen, Anders; Andersen, Lars
2008-01-01
Numerous methods are available for the prediction of the axial capacity of piles in clay. In this paper, two well-known models are considered, namely the current API-RP2A (1987 to present) and the recently developed ICP method. The latter is developed by Jardine and his co-workers at Imperial Col...
Energy Technology Data Exchange (ETDEWEB)
Mohan, R.; Marshall, C.; Ghadiali, N.; Wilkowski, G. [Battelle, Columbus, OH (United States)
1997-04-01
This paper summarizes work on angled through-wall-crack initiation and combined loading effects on ferritic nuclear pipe performed as part of the Nuclear Regulatory Commission`s research program entitled {open_quotes}Short Cracks In Piping an Piping Welds{close_quotes}. The reader is referred to Reference 1 for details of the experiments and analyses conducted as part of this program. The major impetus for this work stemmed from the observation that initially circumferentially oriented cracks in carbon steel pipes exhibited a high tendency to grow at a different angle when the cracked pipes were subjected to bending or bending plus pressure loads. This failure mode was little understood, and the effect of angled crack grown from an initially circumferential crack raised questions about how cracks in a piping system subjected to combined loading with torsional stresses would behave. There were three major efforts undertaken in this study. The first involved a literature review to assess the causes of toughness anisotropy in ferritic pipes and to develop strength and toughness data as a function of angle from the circumferential plane. The second effort was an attempt to develop a screening criterion based on toughness anisotropy and to compare this screening criterion with experimental pipe fracture data. The third and more significant effort involved finite element analyses to examine why cracks grow at an angle and what is the effect of combined loads with torsional stresses on a circumferentially cracked pipe. These three efforts are summarized.
International Nuclear Information System (INIS)
Mohan, R.; Marschall, C.; Krishnaswamy, P.; Brust, F.; Ghadiali, N.; Wilkowski, G.
1995-04-01
This topical report summarizes the work on angled crack growth and combined loading effects performed within the Nuclear Regulatory Commission's research program entitled open-quotes Short Cracks in Piping and Piping Weldsclose quotes. The major impetus for this work stemmed from the observation that initial circumferential cracks in carbon steel pipes exhibited angular crack growth. This failure mode was little understood, and the effect of angled crack growth from an initially circumferential crack raised questions of how pipes under combined loading with torsional stresses would behave. There were three major conclusions from this work. The first was that virtually all ferritic nuclear pipes will have toughness anisotropy. The second was that the ratio of the normalized crack driving force (as a function of angle) to the normalized toughness (also as a function of the angle of crack growth) showed that there was an equal likelihood of cracks growing at any angle between 25 and 65 degrees. This agreed with the scatter of crack growth angles observed in pipe tests. Third, for combined loads with torsional stresses, an effective moment allows pure bending analyses to be used up to crack initiation. Crack opening area under combined loads could also be determined in this mariner
International Nuclear Information System (INIS)
Mohan, R.; Marshall, C.; Ghadiali, N.; Wilkowski, G.
1997-01-01
This paper summarizes work on angled through-wall-crack initiation and combined loading effects on ferritic nuclear pipe performed as part of the Nuclear Regulatory Commission's research program entitled open-quotes Short Cracks In Piping an Piping Weldsclose quotes. The reader is referred to Reference 1 for details of the experiments and analyses conducted as part of this program. The major impetus for this work stemmed from the observation that initially circumferentially oriented cracks in carbon steel pipes exhibited a high tendency to grow at a different angle when the cracked pipes were subjected to bending or bending plus pressure loads. This failure mode was little understood, and the effect of angled crack grown from an initially circumferential crack raised questions about how cracks in a piping system subjected to combined loading with torsional stresses would behave. There were three major efforts undertaken in this study. The first involved a literature review to assess the causes of toughness anisotropy in ferritic pipes and to develop strength and toughness data as a function of angle from the circumferential plane. The second effort was an attempt to develop a screening criterion based on toughness anisotropy and to compare this screening criterion with experimental pipe fracture data. The third and more significant effort involved finite element analyses to examine why cracks grow at an angle and what is the effect of combined loads with torsional stresses on a circumferentially cracked pipe. These three efforts are summarized
Analysis of 2-spar cantilever wings with special reference to torsion and load transference
Kuhn, Paul
1936-01-01
This report deals with the analysis of 2-spar cantilever wings in torsion, taking cognizance of the fact that the spars are not independent, but are interconnected by ribs and other structural members. The principles of interaction are briefly explained, showing that the mutual relief action occurring depends on the "pure torsional stiffness" of the wing cross section. Various practical methods of analysis are outlined. The "Friedrichs-Von Karman equations" are shown to require the least amount of labor. Numerical examples by the several methods of analysis are given and the agreement between the calculation and experiment is shown.
Directory of Open Access Journals (Sweden)
Zheng Yang
2013-01-01
Full Text Available Torsional spring-loaded antibacklash gear which can improve the transmission precision is widely used in many precision transmission fields. It is very important to investigate the dynamic characteristics of antibacklash gear. In the paper, applied force analysis is completed in detail. Then, defining the starting point of double-gear meshing as initial position, according to the meshing characteristic of antibacklash gear, single- or double-tooth meshing states of two gear pairs and the transformation relationship at any moment are determined. Based on this, a nonlinear model of antibacklash gear with time-varying friction and meshing stiffness is proposed. The influences of friction and variations of torsional spring stiffness, damping ratio and preload on dynamic transmission error (DTE are analyzed by numerical calculation and simulation, and the results show that antibacklash gear can increase the composite meshing stiffness; when the torsional spring stiffness is large enough, the oscillating components of the DTE (ODTE and the RMS of the DTE (RDTE trend to be a constant value; the variations of ODTE and RDTE are not significant, unless preload exceeds a certain value.
Becker, Edward H; Kim, Hyunchul; Shorofsky, Michael; Hsieh, Adam H; Watson, Jeffrey D; OʼToole, Robert V
2017-05-01
Biomechanical studies of osteoporotic bone have used synthetic models rather than cadaveric samples because of decreased variability, increased availability, and overall ease of the use of synthetic models. We compared the torsional mechanical properties of cadaveric osteoporotic bone with those of currently available synthetic osteoporotic bone analogues. We tested 12 osteoporotic cadaveric humeri and 6 specimens each of 6 types of synthetic analogues. A 5-mm fracture gap model and posterior plating technique with 4.5-mm narrow 10-hole locking compression plate were used. Torque was applied to a peak of ±10 N·m for 1000 cycles at 0.3 Hz. Data were continuously collected during cyclical and ramped loading with a servohydraulic materials testing system. Cadaveric bone had a 17% failure rate before completing 1000 cycles. Three osteoporotic bone models had 100% failure (P Osteoporotic bone analogues had torsional mechanical properties different from those of osteoporotic cadaveric specimens. The differences between osteoporotic cadaveric humeri and synthetic osteoporotic bone analogues ranged from profound with complete catastrophic failure after a few cycles to subtler differences in stiffness and strain hardening. These findings suggest that different bone analogue models vary substantially in their torsional mechanical properties and might not be appropriate substitutes for cadaveric bone in biomechanical studies of osteoporotic bone.
A simplified analysis method for piled raft and pile group foundations with batter piles
Kitiyodom, Pastsakorn; Matsumoto, Tatsunori
2002-11-01
A simplified method of numerical analysis has been developed to estimate the deformation and load distribution of piled raft foundations subjected to vertical, lateral, and moment loads, using a hybrid model in which the flexible raft is modelled as thin plates and the piles as elastic beams and the soil is treated as springs. Both the vertical and lateral resistances of the piles as well as the raft base are incorporated into the model. Pile-soil-pile, pile-soil-raft and raft-soil-raft interactions are taken into account based on Mindlin's solutions for both vertical and lateral forces. The validity of the proposed method is verified through comparisons with several existing methods for single piles, pile groups and piled rafts. Workable design charts are given for the estimation of the lateral displacement and the load distribution of piled rafts from the stiffnesses of the raft alone and the pile group alone. Additionally, parametric studies were carried out concerning batter pile foundations. It was found that the use of batter piles can efficiently improve the deformation characteristics of pile foundations subjected to lateral loads.
Harasid, Harun; Roesyanto; Iskandar, Rudi; Silalahi, Sofyan A.
2018-03-01
Piling Foundation is one of the foundations which is used to penetrate its load through soil layer. The power carried by the piling is obtained from the end bearing capacity, that is, the compressive end piling and friction bearing capacity obtained from friction bearing and adhesive capacity between the piling and the soil around it. The investigation on the Standard Penetration Test is aimed to get the description of soil layer, based on the type and color of soil through visual observation, and soil characteristics. SPT data can be used to calculate bearing capacity. Besides investigating the SPT, this study is also been equipped by taking the samples in laboratory and loading test on the piling and Ducth Cone Penetrometer (DCP) data to confirm its bearing capacity. This study analyzed bearing capacity and settlement in the square pile of 40X40 cm in diameter in a single pile or grouped, using an empirical method, AllPile program, Plaxis program, and comparing the result with interpreting its loading test in the foundation of Rusunawa project, Jatinegara, Jakarta. The analysis was been done by using the data on soil investigation and laboratory by comparing them with Mohr-Coulomb soil model. Ultimate bearing capacity from the SPT data in the piling of 15.4 meters was 189.81 tons and the parameter of soil shear strength was 198.67 tons. The sander point, based on Aoki and De Alencar bearing capacity was 276.241 tons and based on Mayerhoff it was 305.49 tons. Based on the loading test of bearing capacity, unlimited bearing capacity for the three methods was Davisson (260 tons), Mazurkiewich (270 tons), and Chin (250 tons). The efficiency of grouped piles according to Converse-Library Equation method = 0.73, according to Los Angeles Group Action Equation method = 0.59, and according to Sheila-Keeny method = 0.94. Bearing capacity based on piling strength was 221.76 tons, bearing capacity based on calendaring data was 201.71 tons, and lateral bearing capacity of a
DEFF Research Database (Denmark)
Truong, P.; Lehane, B. M.; Zania, Varvara
2018-01-01
A systematic study into the response of monopiles to lateral cyclic loading in medium dense and dense sand was performed in beam and drum centrifuge tests. The centrifuge tests were carried out at different cyclic load and magnitude ratios, while the cyclic load sequence was also varied...
Technology of pile dynamic testing
Holeyman, Alain; The 4th International Conference on the Application of Stress-Wave Theory to Piles
1992-01-01
Because of the recent larger availability and higher performance of pile testing and monitoring equipment, pile dynamic testing has become part of many present day civil engineering projects. This report covers the past and state-of-the-art technological aspects of pile dynamic testing: testing methods, loading equipment, and measurements, including their acquisition and interpretation. Three major pile dynamic testing methods are distinguished based on means and objectives: high-strain testi...
2016-04-01
The objectives of this research study are to develop a three-dimensional FE : model for simulating the behavior of a battered pile group foundation subjected : to lateral loading, and to verify the model using results from a unique static : lateral l...
Interaction of crippling and torsional-flexural instabilities for centrally loaded columns
Walls, J. C.
1970-01-01
Empirical technique predicts failure loads for centrally loaded columns with thin-walled, open cross sections. Interaction of two failure modes is predicted by modification of the Johnson-Euler equation.
International Nuclear Information System (INIS)
Bocher, L.; Delobelle, P.
1997-01-01
This paper is concerned with the experimental determination of the behaviour of a 316 L austenitic stainless steel at room temperature and under non proportional cyclic strainings in tension-torsion-internal and external pressures. The two or three sinusoidal strains were applied both in and out-of-phase and the main investigations deal with the additional hardening due to multiaxiality of the loadings. Typical stabilized hysteresis loops are presented. With respect to the maximum additional hardening the different tests can be classified as follows: in phase tests, out-of-phase internal-external pressures tests, out-of-phase tension-torsion tests and finally tension-torsion-pressure with significant phase angles. (orig.)
Response of stiff piles in sand to long-term cyclic lateral loading
DEFF Research Database (Denmark)
Bakmar, Christian LeBlanc; Houlsby, Guy T.; Byrne, Byron W.
2010-01-01
The monopile is currently the preferred foundation type for most offshore wind farms. Whilst static capacity of the monopile is important, a safe design must also address issues of accumulated rotation and stiffness after long-term cyclic loading. Design guidance on this issue is limited. To addr...
DESIGN AND CONSTRUCTION OF A TORSIONAL FATIGUE TESTING MACHINE OPERATED BY INERTIAL LOADS
Directory of Open Access Journals (Sweden)
FABIO MARCELO PEÑA BUSTOS
2012-01-01
Full Text Available En este artículo se presenta el desarrollo de una máquina para pruebas de fatiga torsional en materiales metálicos. La máquina se considera de tipo I según la clasificación de Weibull debido a que la falla es producida por una carga de origen inercial. El principio de operación se basa en el movimiento alternante que produce la transmisión de una máquina lavadora. La carga inercial es producida por un volante ubicado en la parte superior de la máquina. A diferencia de muchas máquinas de fatiga que generan la alternancia de los esfuerzos mediante la reubicación o giro de la probeta respecto a cargas que son uniformes en el tiempo, en el diseño realizado se evidencia cómo las cargas inerciales debidas a las aceleraciones de los elementos mecánicos generan cargas de carácter alternante que llegan a ocasionar fallas por fatiga.
Yeager, W. T.; Mantay, W. R.
1981-01-01
The Langley transonic dynamics tunnel was used to determine the degree of correlation between rotor performance and the dynamic twist generated by changes in blade tip geometry using an articulated rotor with four different tip geometries at advance ratios of 0.20, 0.30 and 0.35. Based on the data obtained, it is concluded that: (1) there appears to be no strong correlation between blade torsion loads and rotor performance prediction; (2) for a given rotor task at each advance ratio investigated, both the azimuthal variation of torsional moment and the mean torsional moment at 81% radius are configuration dependent; (3) reducing the nose down twist on the advancing blade appears to be more important to forward flight performance than increasing the nose down twist on the retreating blade; (4) the rotor inflow model used was important in predicting the performance of the adaptive rotor; and (5) neither rigid blade solidity effects, inflow environment, nor blade torsion loads can be used alone to accurately predict active rotor performance.
Directory of Open Access Journals (Sweden)
Ali Ghorbani
2017-01-01
Full Text Available Coupled Piled Raft Foundations (CPRFs are broadly applied to share heavy loads of superstructures between piles and rafts and reduce total and differential settlements. Settlements induced by static/coupled static-dynamic loads are one of the main concerns of engineers in designing CPRFs. Evaluation of induced settlements of CPRFs has been commonly carried out using three-dimensional finite element/finite difference modeling or through expensive real-scale/prototype model tests. Since the analyses, especially in the case of coupled static-dynamic loads, are not simply conducted, this paper presents two practical methods to gain the values of settlement. First, different nonlinear finite difference models under different static and coupled static-dynamic loads are developed to calculate exerted settlements. Analyses are performed with respect to different axial loads and pile’s configurations, numbers, lengths, diameters, and spacing for both loading cases. Based on the results of well-validated three-dimensional finite difference modeling, artificial neural networks and evolutionary polynomial regressions are then applied and introduced as capable methods to accurately present both static and coupled static-dynamic settlements. Also, using a sensitivity analysis based on Cosine Amplitude Method, axial load is introduced as the most influential parameter, while the ratio l/d is reported as the least effective parameter on the settlements of CPRFs.
Assessment of wind turbine drive-train fatigue loads under torsional excitation
DEFF Research Database (Denmark)
Gallego Calderon, Juan Felipe; Natarajan, Anand
2015-01-01
This paper establishes validated models that can accurately account for the dynamics of the gearbox, along with the external dynamics that excite the system. A drive-train model implementation is presented where the gearbox and generator are coupled to the wind turbine structure in a dynamic...... allows the computation of the bearing and gear-mesh loads. The proposed models are validated by experiments from a 750 kW test-rig. The drive-train model is configured for a 5 MW power capacity and coupled to the corresponding wind turbine and load simulations are carried out under turbulent wind...
Directory of Open Access Journals (Sweden)
Faeze Jafari
2017-02-01
Full Text Available The aim of designing of the structural members is withstanding the members or structures against the different loading conditions such that the safety of the system could be preserved. The conventional method for designing of reinforced concrete members in Iranian concrete code is based on load and resistance factor. Although, load and resistance parameters are random variables, and in the mentioned Code the constant values have been designated for them during the designing procedure. Accounting these factors as the constants parameters will ultimately be led to the unsafe and uneconomical designs. The main purpose of this paper is probability-based designing of reinforcement concrete beams under simultaneous effects of bending, shear and torsion actions. For this purpose, analytical relations of the limit states for combination of bending, shear and torsion have been developed. Using the method, the structural designers could be fulfilled the designing of the RC beams based on the importance of structures and the required safety indexes of the owners. The next goal of this investigation is evaluation and calibration of load and resistance factors for desired safety index. The economic and fully probabilistic designing of concrete beams for simultaneous effects of bending, shear and torsion are available by implementing the proposed design procedures. In order to calculate the safety indexes a computer program has been written in the MATLAB environment, and the Monte Carlo simulation technique has been utilized.
Modeling of Batter Pile Behavior under Lateral Soil Movement
Chen, C. Y.; Hsu, H. Q.
2017-06-01
Pile foundation is frequently used when structures are located on weak sublayers or are at risk from lateral loadings such as earthquakes. The design of pile foundations has recently become crucial to stop slope movement. To understand the behavior of pile foundations subjected to lateral soil movement, the three-dimensional Fast Lagrangian Analysis of Continua (FLAC3D) program was used to perform numerical simulations, which can reduce the cost of field testing. Vertical piles and batter piles were combined into 3 × 3 pile groups, and the response of batter piles to soil movement was analyzed. The outer batter piles led to an increased bending moment in the middle, vertical pile row. Increasing the pile spacing and the presence of battered piles reduced the pile group’s displacement. The batter pile group’s maximum bending moment was smaller than the vertical pile group’s in sand soil, but 5-8 times higher in clay soil.
Directory of Open Access Journals (Sweden)
Evgenij Kalentev
2017-06-01
Full Text Available The paper presents the results of a numerical analysis of the stress-strain state of a rope strand with linear contact under tension and torsion loading conditions. Calculations are done using the ANSYS software package. Different approaches to calculation of the stress-strain state of ropes are reviewed, and their advantages and deficiencies are considered. The analysis of the obtained results leads us to the conclusion that the proposed method can be used in engineering calculations.
Energy Technology Data Exchange (ETDEWEB)
Zhang Xinjian [School of Chemical Engineering and Technology, Tianjin University, 92 Weijin Road, Tianjin 300072 (China); Huang Lu [Department of Materials Science and Engineering, University of Tennessee, TN 37996 (United States); Key Laboratory of Aerospace Materials and Performance (Ministry of Education), School of Materials Science and Engineering, Beijing University of Aeronautics and Astronautics, Beijing 100191 (China); Chen Xu, E-mail: xchen@tju.edu.cn [School of Chemical Engineering and Technology, Tianjin University, 92 Weijin Road, Tianjin 300072 (China); Liaw, Peter K. [Department of Materials Science and Engineering, University of Tennessee, TN 37996 (United States); An Ke [Neutron Scattering Sciences Division, Oak Ridge National Laboratory, TN 37831 (United States); Zhang Tao [Key Laboratory of Aerospace Materials and Performance (Ministry of Education), School of Materials Science and Engineering, Beijing University of Aeronautics and Astronautics, Beijing 100191 (China); Wang Gongyao [Department of Materials Science and Engineering, University of Tennessee, TN 37996 (United States)
2010-11-15
Research highlights: {yields} Fe{sub 75}Mo{sub 5}P{sub 10}C{sub 7.5}B{sub 2.5} bulk-metallic glass exhibits a brittle characteristic under torsional loading. {yields} The BMG occurs in a tensile mode failure under torsional loading. {yields} A slight cyclic-hardening behavior was observed in the initial loading cycles during torsional-fatigue tests. {yields} The torsional fatigue-fracture surface consists of three main regions. - Abstract: Pure- and cyclic-torsional studies were conducted on a Fe{sub 75}Mo{sub 5}P{sub 10}C{sub 7.5}B{sub 2.5} (atomic percent, at.%) bulk-metallic glass at room temperature for an understanding of its damage and fracture mechanisms. Under pure-torsional loading, the metallic glass exhibited very little plastic strain before fracture. The fracture initiated along the maximum tensile-stress plane, which is about 45{sup o} to the axial direction. The shear-fracture strength ({approx}510 MPa) is much lower than the compressive-fracture strength ({approx}3280 MPa), which suggests that different deformation mechanisms be present under various loading modes. Instead of an apparent vein-type structure, the fracture morphologies revealed a crack-initiation site, a mirror region, a mist region, and a hackle region. Under cyclic-torsional loading, fatigue cracks initiated from casting defects, and propagate generally along the maximum tensile-stress plane. A slight cyclic-hardening behavior was observed in initial loading steps. The fatigue-fracture surface consists of three main regions: the fatigue crack-initiation, crack-propagation, and final-fast-fracture areas. The striations resulting from the blunting and re-sharpening of the fatigue crack tip were observed in the crack-propagation region. Based on these results, the damage and fracture mechanisms of the metallic glass induced by torsional loadings are elucidated.
Shakedown and ratchetting under tension-torsion loadings: analysis and experiments
International Nuclear Information System (INIS)
Heitzer, M.; Staat, M.; Reiners, H.; Schubert, F.
2003-01-01
Structural design analyses are conducted with the aim of verifying the exclusion of ratchetting. To this end it is important to make a clear distinction between the shakedown range and the ratchetting range. The performed experiment comprised a hollow tension specimen which was subjected to alternating axial forces, superimposed with constant moments. First, a series of uniaxial tests has been carried out in order to calibrate a bounded kinematic hardening rule. The load parameters have been selected on the basis of previous shakedown analyses with the PERMAS code using a kinematic hardening material model. It is shown that this shakedown analysis gives reasonable agreement between the experimental and the numerical results. A linear and a nonlinear kinematic hardening model of two-surface plasticity are compared in material shakedown analysis
Directory of Open Access Journals (Sweden)
A. S. Alnuaimi
2008-12-01
Full Text Available This paper presents a non-linear analysis of three reinforced and two partially prestressed concrete solid beams based on a 20 node isoparametric element using an in-house 3D finite element program. Anon linear elastic isotropic model, proposed by Kotsovos, was used to model concrete behaviour, while steel was modelled as an embedded element exhibiting elastic-perfectly plastic response. Allowance was made for shear retention and for tension stiffening in concrete after cracking. Only in a fixed direction, smeared cracking modelling was adopted. The beams dimensions were 300x300 mm cross section, 3800 mm length and were subjected to combined bending, torsion and shear. Experimental results were compared with the non-linear predictions. The comparison was judged by load displacement relationship, steel strain, angle of twist, failure load, crack pattern and mode of failure. Good agreement was observed between the predicted ultimate load and the experimentally measured loads. It was concluded that the present program can confidently be used to predict the behaviour and failure load of reinforced and partially prestressed concrete solid beams subjected to a combined load of bending, torsion and shear.
Yeager, W. T., Jr.; Mantay, W. R.
1983-01-01
A passive means of tailoring helicopter rotor blades to improve performance and reduce loads was evaluated. The parameters investigated were blade torsional stiffness, blade section camber, and distance between blade structural elastic axis and blade tip aerodynamic center. This offset was accomplished by sweeping the tip. The investigation was conducted at advance ratios of 0.20, 0.30, and 0.40. Data are presented without analysis; however, cross referencing of performance data and harmonic loads data may be useful to the analyst for validating aeroelastic theories and design methodologies as well as for evaluating passive aeroelastic tailoring or rotor blade parameters.
Otsuka, Hisanori; Hattori, Masahiro
When the structures, for example arch bridges are subjected bending moments and torsional moments, the strength and rigidity of the members decline compared to those of pure bending or torsion load condition. However, any analysis soft don't consider interrelation between bending and torsion ,and effects of torsional moments have not been considered severely in seismic design. In this study, the authors proposed analysis technique considering interaction between bending and torsion to estimate torsional moments severely, and formulized the analysis tools for this technique. These are interaction curve, skeleton for combined load, hysteresis for torsion. Moreover, the authors analyzed a RC arch bridge using this method, and inspected the validity of comparing the results obtained equivalent linear analysis about torsion and nonlinear torsional analysis not considering the interaction between bending and torsion.
Directory of Open Access Journals (Sweden)
Siddharth Pramod Dubhashi
2016-01-01
Full Text Available Torsion of the vermiform appendix is a rare condition detectable only at operation. It can be primary or secondary. This is a case report of 52-year-old female with 180° anti-clockwise rotation of the appendix. Torsion can further leads to strangulation and infarction of the organ. Appendicular torsion could be included in the differential diagnosis of pain in right iliac fossa.
Mono pile foundation. Final report
Energy Technology Data Exchange (ETDEWEB)
Lyngesen, S.; Brendstrup, C.
1997-02-01
The use of mono piles as foundations for maritime structures has been developed during the last decades. The installation requirements within the offshore sector have resulted in equipment enabling driving of piles up to 3-4 m to large penetration depths. The availability of this equipment has made the use of large mono piles feasible as foundations for structures like wind turbines. The mono pile foundations consists of three parts; the bare pile, a conical transition and a boat landing. All parts are prefitted at the yard in order to minimise the installation work that has to be carried out offshore. The study of a mono pile foundations for a 1.5 MW wind turbine has been conducted for two locations, Horns Rev and Roedsand. Three different water depths: 5, 8 and 11 m have been investigated in the study. The on-site welding between pile and conical transition is performed by an automatic welding machine. Final testing and eventually repair of the weld are conducted at least 16 hours after welding. This is followed by final installation of J-tube, tie-in to subsea cables and installation of the impressed current system for corrosive protection of the mono pile. The total cost for procurement and installation of the mono pile using the welded connection is estimated. The price does not include procurement and installation of access platform and boat landing. These costs are estimated to 250.000 DKK. Depending on water depth the cost of the pile ranges from 2,2 to 2,7 million DKK. Procurement and fabrication of the pile are approx. 75% of the total costs. The remaining 25% are due to installation. The total costs are very sensitive to the unit price of pile steel. During the project it became obvious that ice load has a very large influence on the dimensions of the mono pile. (EG)
African Journals Online (AJOL)
TESTICULAR TORSION: EXPERIENCE IN THE MIDDLE BELT OF NIGERIA. S.A. KURANGA AND G.A. RAHMAN. Department of Surgery, University of l/orin Teaching Hospital, Ilorin, Nigeria. Objective To determine the fate of the testis affected by testicular torsion (TT) in relation to the duration of the symptoms and to.
International Nuclear Information System (INIS)
Ogata, Takashi; Nitta, Akito
1994-01-01
Creep-fatigue damage in high temperature structural components in a FBR progress under multiaxial stress condition depending on their operating conditions and configuration. Therefore, multiaxial stress effects on creep-fatigue damage evolution must be clarified to make precise creep-fatigue damage evaluation of these components. In this study, creep-fatigue tests in FBR high temperature materials such as SUS304, 316FR stainless steels and a modified 9Cr steel were conducted under biaxial stress subjecting tension-compression and torsion loading, in order to examine biaxial stress effects on failure mechanism and life property, and to discuss creep-fatigue life evaluation methods under biaxial stress. Main results obtained in this study are summarized as follows: 1. The main cracks under cyclic torsion loading propagated by shear mode in three materials. But intergranular failure was occurred in SUS304 and 316FR, and transgranular failure was observed in Mod.9Cr steel. 2. Nonlinear damage accumulation model proposed based on uniaxial creep-fatigue test results was extended to apply for creep-fatigue damage evaluation under biaxial stress state by considering the biaxial stress effects on fatigue and creep damage evolution. 3. It was confirmed that creep-fatigue life under biaxial stress could be predicted by the extended evaluation method with higher accuracy than existing methods. (author)
Luo, Min
2018-02-01
On the basis of consulting data, the bearing mechanism of gravel pile composite foundation is analyzed in this paper. The use of ANSYS software under flexible foundation according to the plum blossoms gravel pile additional stress between pile and soil additional stress distribution, load on pile top stress and pile bearing rate of modulus ratio between pile and soil on the pile top stress and rate of pile bearing capacity, pile-soil effect the stress ratio was calculated and analyzed, providing reasonable design reference for the design of gravel pile composite foundation.
Introduction of effective piles in a base structure
Directory of Open Access Journals (Sweden)
В.Б. Кашка
2005-03-01
Full Text Available Design features of effective piles such as СВ and their advantages in use are considered at the device of the pile bases in comparison with widely widespread types of piles. From results of comparative tests of piles under static pressing loading in different earth conditions the tendency of redistribution of bearing (carrying ability between a trunk and expansions an effective pile such as СВ was determined on earth conditions.
Measurement and Analysis of Horizontal Vibration Response of Pile Foundations
Directory of Open Access Journals (Sweden)
A. Boominathan
2007-01-01
Full Text Available Pile foundations are frequently used in very loose and weak deposits, in particular soft marine clays deposits to support various industrial structures, power plants, petrochemical complexes, compressor stations and residential multi-storeyed buildings. Under these circumstances, piles are predominantly subjected to horizontal dynamic loads and the pile response to horizontal vibration is very critical due to its low stiffness. Though many analytical methods have been developed to estimate the horizontal vibration response, but they are not well validated with the experimental studies. This paper presents the results of horizontal vibration tests carried out on model aluminium single piles embedded in a simulated Elastic Half Space filled with clay. The influence of various soil and pile parameters such as pile length, modulus of clay, magnitude of dynamic load and frequency of excitation on the horizontal vibration response of single piles was examined. Measurement of various response quantities, such as the load transferred to the pile, pile head displacement and the strain variation along the pile length were done using a Data Acquisition System. It is found that the pile length, modulus of clay and dynamic load, significantly influences the natural frequency and peak amplitude of the soil-pile system. The maximum bending moment occurs at the fundamental frequency of the soil-pile system. The maximum bending moment of long piles is about 2 to 4 times higher than that of short piles and it increases drastically with the increase in the shear modulus of clay for both short and long piles. The active or effective pile length is found to be increasing under dynamic load and empirical equations are proposed to estimate the active pile length under dynamic loads.
Pullout capacity of batter pile in sand.
Nazir, Ashraf; Nasr, Ahmed
2013-03-01
Many offshore structures are subjected to overturning moments due to wind load, wave pressure, and ship impacts. Also most of retaining walls are subjected to horizontal forces and bending moments, these forces are due to earth pressure. For foundations in such structures, usually a combination of vertical and batter piles is used. Little information is available in the literature about estimating the capacity of piles under uplift. In cases where these supporting piles are not vertical, the behavior under axial pullout is not well established. In order to delineate the significant variables affecting the ultimate uplift shaft resistance of batter pile in dry sand, a testing program comprising 62 pullout tests was conducted. The tests are conducted on model steel pile installed in loose, medium, and dense sand to an embedded depth ratio, L/d, vary from 7.5 to 30 and with various batter angles of 0°, 10°, 20°, and 30°. Results indicate that the pullout capacity of a batter pile constructed in dense and/or medium density sand increases with the increase of batter angle attains maximum value and then decreases, the maximum value of Pα occurs at batter angle approximately equal to 20°, and it is about 21-31% more than the vertical pile capacity, while the pullout capacity for batter pile that constructed in loose sand decreases with the increase of pile inclination. The results also indicated that the circular pile is more resistant to pullout forces than the square and rectangular pile shape. The rough model piles tested is experienced 18-75% increase in capacity compared with the smooth model piles. The suggested relations for the pullout capacity of batter pile regarding the vertical pile capacity are well predicted.
Pullout capacity of batter pile in sand
Directory of Open Access Journals (Sweden)
Ashraf Nazir
2013-03-01
Full Text Available Many offshore structures are subjected to overturning moments due to wind load, wave pressure, and ship impacts. Also most of retaining walls are subjected to horizontal forces and bending moments, these forces are due to earth pressure. For foundations in such structures, usually a combination of vertical and batter piles is used. Little information is available in the literature about estimating the capacity of piles under uplift. In cases where these supporting piles are not vertical, the behavior under axial pullout is not well established. In order to delineate the significant variables affecting the ultimate uplift shaft resistance of batter pile in dry sand, a testing program comprising 62 pullout tests was conducted. The tests are conducted on model steel pile installed in loose, medium, and dense sand to an embedded depth ratio, L/d, vary from 7.5 to 30 and with various batter angles of 0°, 10°, 20°, and 30°. Results indicate that the pullout capacity of a batter pile constructed in dense and/or medium density sand increases with the increase of batter angle attains maximum value and then decreases, the maximum value of Pα occurs at batter angle approximately equal to 20°, and it is about 21–31% more than the vertical pile capacity, while the pullout capacity for batter pile that constructed in loose sand decreases with the increase of pile inclination. The results also indicated that the circular pile is more resistant to pullout forces than the square and rectangular pile shape. The rough model piles tested is experienced 18–75% increase in capacity compared with the smooth model piles. The suggested relations for the pullout capacity of batter pile regarding the vertical pile capacity are well predicted.
2014-10-01
The overall goal of this project is the experimental evaluation and design of unfilled and concrete-filled FRP : composite piles for load-bearing in bridges. This report covers Task 1, Mechanical Properties of FRP Piles. : Mechanical and geotechnic...
International Nuclear Information System (INIS)
Sharpe, Eric
2003-01-01
In this article we explain discrete torsion. Put simply, discrete torsion is the choice of orbifold group action on the B field. We derive the classification H 2 (Γ,U(1)), the twisted sector phases appearing in string loop partition functions, Douglas's description of discrete torsion for D-branes in terms of a projective representation of the orbifold group, and outline how the results of Vafa and Witten fit into this framework. In addition, we observe that additional degrees of freedom (known as shift orbifolds) appear in describing orbifold group actions on B fields, in addition to those classified by H 2 (Γ,U(1)), and explain how these degrees of freedom appear in terms of twisted sector contributions to partition functions and in terms of orbifold actions on D-brane worldvolumes. This paper represents a technically simplified version of prior papers by the author on discrete torsion. We repeat here technically simplified versions of results from those papers, and have included some new material
African Journals Online (AJOL)
A‑2/103, Shivranjan Towers, Someshwarwadi, Pashan, Pune ‑ 411 008,. Maharashtra, India. E‑mail: spdubhashi@gmail.com. INTRODUCTION. Acute appendicitis presents with pain in right iliac fossa. Torsion of the vermiform appendix, though rare, also presents in a similar fashion, and it is detectable only at operation.[1].
The relationship between torsional rigidity and bending strength ...
African Journals Online (AJOL)
torsional buckling resistance of bending members and when members are subjected to torsional loads. This study was based on a series of laboratory experiments on actual sized timber with the focus and emphasis on mechanical properties and ...
DEFF Research Database (Denmark)
Brasso, K; Andersen, L; Kay, L
1993-01-01
Thirty-five patients were examined 6-11 years after operation for torsion of the testis. Loss of testicular tissue was significantly associated with long preoperative duration of symptoms and with low postoperative sperm counts. The sex hormones were normal in the majority of patients but there w...... to the sperm count and concentration. Measurement of carnitine levels in seminal plasma, as a sign of vas deferens obstruction or dysfunction of epididymis, and of autoantibodies against spermatozoa revealed no significant findings....
Some Remarks on Foundation Pile Testing Procedures
Rybak, Jarosław
2017-10-01
This work presents the review of pile capacity testing techniques. In an overview, the key points in pile designing are: determination of the appropriate computational schemes, reliable data on loads and the properties of structural materials (in particular, of the soil mass, which is marked by the greatest variability). The procedure of constructing a pile foundation should include: carrying out soil tests in the scope that ensures safe designing, selecting a piling technology that is relevant both to geotechnical conditions and expected loads, drafting a piling design together with the design of load tests, setting up a testing station for further load tests, static and/or dynamic tests of pile load capacity, preceded by supplementary soil tests when the conditions of test pile installation fail to comply with the design assumptions or when the pile length exceeds the depth of the previously investigated soil, making documentation of load capacity tests (with an additional correction of the piling design), the actual piling (ongoing analysis of pile driving logs and, if necessary, testing the piles’ integrity), drawing up the as-built documentation. Unfortunately, the design is corrected after the load test have been conducted only if the piles fail to show the designed bearing capacity. The designer is then obliged to revise the design assumptions on the basis of tests results. If the test results account for the a greater bearing capacity than necessary and it would be recommendable to limit the extent of the planned (i.e. set out in the contract) piling works, usually neither the contractor nor the designer, nor even the Construction Site Supervisor, acting for the benefit of the Investor, are willing to take on the responsibility for reducing the scope of the piling works. The necessity of conducting additional control tests before and during the implementation of the construction project is often treated by the investors as an attempt at extorting extra
A new elasto-plastic spring element for cyclic loading of piles using the p-y curve concept
DEFF Research Database (Denmark)
Hededal, Ole; Klinkvort, Rasmus Tofte
2010-01-01
in terms of monotonic loading (until failure) as e.g. prescribed byAPI (2000). However, the cyclic and dynamic performance is only to a limited degree accounted for. Here the elasto-plastic framework is applied allowing definition of unloading-reloading branches, hence enabling modeling of cyclic response......” as e.g. seen from centrifuge tests carried out. This article presents the theoretical formulations, discusses numerical implementation and finally presents simulations....
Pile group program for full material modeling and progressive failure.
2008-12-01
Strain wedge (SW) model formulation has been used, in previous work, to evaluate the response of a single pile or a group of piles (including its : pile cap) in layered soils to lateral loading. The SW model approach provides appropriate prediction f...
Numerical analysis of kinematic soil—pile interaction
Castelli, Francesco; Maugeri, Michele; Mylonakis, George
2008-07-01
In the present study, the response of singles pile to kinematic seismic loading is investigated using the computer program SAP2000@. The objectives of the study are: (1) to develop a numerical model that can realistically simulate kinematic soil-structure interaction for piles accounting for discontinuity conditions at the pile-soil interface, energy dissipation and wave propagation; (2) to use the model for evaluating kinematic interaction effects on pile response as function of input ground motion; and (3) to present a case study in which theoretical predictions are compared with results obtained from other formulations. To evaluate the effects of kinematic loading, the responses of both the free-field soil (with no piles) and the pile were compared. Time history and static pushover analyses were conducted to estimate the displacement and kinematic pile bending under seismic loadings.
Design Implementation of Pile Foundation
Jaiswal, Manish
2017-01-01
The objective of this Bachelor’s thesis was to design a pile foundation for a residential building. The aim was to identify aspects affecting pile foundation design in a challenging environment because the building was to be built on a reclaimed land from the Baltic sea and almost half of the foundation slab would extend into the sea, resulting in very high lateral forces due to ice loading during winter. The site was to be stabilised using deep soil mixing columns. To enable the design,...
Tension Tests On Bored Piles In Sand
DEFF Research Database (Denmark)
Krabbenhøft, Sven; Clausen, Johan; Damkilde, Lars
2006-01-01
The lengths of the bored piles varied from 2 m to 6 m and all were of a diameter of 140 mm. The piles were tested to failure in tension and the load-displacement relations were recorded. The investigation has shown pronounced differences between the load bearing capacities obtained by different...... design methods. The methods proposed by Fleming et al. and Reese & O’Neill seem to produce the best match with the test results....
Experimental Study on Post Grouting Bearing Capacity of Large Diameter Bored Piles
Directory of Open Access Journals (Sweden)
Wang Duanduan
2015-01-01
Full Text Available Post grouting can improve the inherent defects such as the formation of the mud cake at pile side and the sediment at pile end in the process of bored pile construction. Thus post grouting has been widely used in Engineering. The purpose of this paper is to research the influences of post grouting to pile bearing capacity more systematically and intuitively. Combined with the static load test of four test piles in Weihe River Bridge test area of new airport highway in Xi’an, the bearing capacity and settlement of routine piles and post grouting piles are comparatively analyzed. The test results show that under the same geological condition, post grouting can improve the properties of pile tip and pile shaft soil of bored piles significantly, enhance the ultimate resistance, improve the ultimate bearing capacity and reduce the pile tip settlement. Then post grouting can aim to optimize pile foundation.
Energy Technology Data Exchange (ETDEWEB)
Watabe, Y. [Port and Harbour Research Inst., Kanagawa (Japan); Takemura, J.; Kimura, T. [Tokyo Institute of Technology, Tokyo (Japan). Faculty of Engineering
1997-06-21
When embankment is constructed behind a piled bridge abutment in soft clay deposits, long term behavior of ground stability and deformation of piled bridge abutment have been investigated by a series of centrifuge model tests and FEM. After a short term change during the construction of embankment, horizontal displacement of the bridge abutment and bending moment of piles increased with time due to undrained creep of soft clay ground. When ground consolidation was predominant after the sufficient time, they decreased to be stable. Influence of the undrained creep on the behavior of piled bridge abutment was reflected to an increase in the bending moment when the constraint of pile end was sufficiently large, and to an increase in the horizontal displacement when it was small. It was effective to improve the backfill lateral ground and to prevent the lateral flow of ground. For the three-dimensional FEM analysis using a modified Cam-clay model, undrained creep deformation of clay can not be considered. Accordingly, an increase in the long term horizontal displacement of bridge abutment after the construction of embankment can not be grasped. However, pulling-back of piles to the backfill side due to the local consolidation can be grasped. 20 refs., 15 figs., 4 tabs.
Thermomechanical Behavior of Energy Pile Embedded in Sandy Soil
Directory of Open Access Journals (Sweden)
Xu Huang
2018-01-01
Full Text Available The traditional energy pile (solid energy pile has been implemented for decades. However, the design of different kinds of energy piles is still not well understood. In this study, a series of model tests were performed on an aluminum pipe energy pile (PEP in dry sandy soil to investigate the thermal effects on the mechanical behaviors of pipe energy pile. The thermal responses of the PEP were also analyzed. Steady temperatures of the PEP under different working conditions were also compared with that of the solid energy pile. Different loading tests were carried out on four pipe energy piles under three different temperatures of 5, 35, and 50°C, respectively. The bearing capacity change can be interpreted through the load-displacement curves. Experiment results were also compared with the solid energy pile to evaluate bearing capacities of the PEP and the solid energy pile under different temperature conditions. The mobilized shaft resistance was also calculated and compared with the solid energy pile data and the results show that the PEP has a similar load transfer mechanism with the solid energy pile. It could also be found that, for PEPs under working load, plastic displacement would appear after a whole heating cycle.
Reactor G1 - Flux charts in the flat pile
International Nuclear Information System (INIS)
Genthon, J.P.
1957-10-01
Experimental flux charts are available for different pile conditions. Data in these charts are given as points. The flux density at each point is the result of the irradiation and counting of a detector, followed by plotting of this count. All these flux density measurements are relative. The different flux charts studied are always relative to the fiat pile, loading side; this will give us: - the flat pile full for the Laplacian measurement; - the flat pile full for the study of the variation of the cadmium ratio; - the flat pile, central canal empty; - the flat pile, central canal plugged with graphite; - the flat pile, central canal containing a cadmium rod; - the flat pile, central canal containing a thorium rod. (author) [fr
Integrity and As-built capacity of bored pile group
International Nuclear Information System (INIS)
Shaw, D.E.; Kissenpfennig, J.F.; Huemmer, M.R.
1983-01-01
This paper discusses the application of statistical methods to the reliability evaluation of cast-in-place concrete piles. The difficulties associated with pile construction can lead to larger uncertainties than would be associated with normal reinforced concrete structures both due to uncertainty in concrete quality and end bearing capacity. These uncertainties can be dealt with through the use of statistical methods. A statistical model of an individual pile is formulated along with a methodology for determining necessary statistical parameters from results of concrete batch tests, core strength tests and visual logs, sonic geophysical testing methods, and proof tests. Strength models for both static vertical and seismic horizontal loadings are discussed. The overall safety of a pile foundation is dependent upon the distribution of individual pile strength as well as the additional reliability due to the use of a large number of parallel load paths provided by a pile group foundation. The paper presents a mechanical model of global pile behavior which accounts for individual pile ductility along with the possibility of redistribution of loads from weaker to stronger piles. The use of the Monte Carlo method to determine the overall reliability of the pile foundation is discussed. Numerical results for both individual pile behavior as well as overall foundation behavior are presented. (orig.)
Pachla, Henryk
2017-12-01
The idea of strengthening the foundation using injection piles lies in transferring loads from the foundation to the piles anchorage in existing structure and formed in the soil. Such a system has to be able to transfer loads from the foundation to the pile and from the pile onto the soil. Pile structure often reinforced with steel element has to also be able to transfer such a loading. According to the rules of continuum mechanics, the bearing capacity of such a system and a deformation of its individual elements can be determined by way of an analysis of the contact problem of three interfaces. Each of these surfaces is determined by different couples of materials. Those surfaces create: pile-foundation anchorage, bonding between reinforcement and material from which the pile is formed and pilesoil interface. What is essential is that on the contact surfaces the deformation of materials which adhere to each other can vary and depends on the mechanical properties and geometry of these surfaces. Engineering practice and experimental research point out that the failure in such structures occurs at interfaces. The paper is concentrating on presenting the experiments on interaction between cement grout and various types of steel reinforcement. The tests were conducted on the special low pressure injection piles widely used to strengthen foundations of already existing structures of historical buildings due to the technology of formation and injection pressure.
Directory of Open Access Journals (Sweden)
Pachla Henryk
2017-12-01
Full Text Available The idea of strengthening the foundation using injection piles lies in transferring loads from the foundation to the piles anchorage in existing structure and formed in the soil. Such a system has to be able to transfer loads from the foundation to the pile and from the pile onto the soil. Pile structure often reinforced with steel element has to also be able to transfer such a loading. According to the rules of continuum mechanics, the bearing capacity of such a system and a deformation of its individual elements can be determined by way of an analysis of the contact problem of three interfaces. Each of these surfaces is determined by different couples of materials. Those surfaces create: pile-foundation anchorage, bonding between reinforcement and material from which the pile is formed and pilesoil interface. What is essential is that on the contact surfaces the deformation of materials which adhere to each other can vary and depends on the mechanical properties and geometry of these surfaces. Engineering practice and experimental research point out that the failure in such structures occurs at interfaces. The paper is concentrating on presenting the experiments on interaction between cement grout and various types of steel reinforcement. The tests were conducted on the special low pressure injection piles widely used to strengthen foundations of already existing structures of historical buildings due to the technology of formation and injection pressure.
The Settlement Behavior of Piled Raft Interaction in Undrained Soil
DEFF Research Database (Denmark)
Ghalesari, Abbasali Taghavi; Barari, Amin; Amini, Pedram Fardad
2013-01-01
Offshore piled raft foundations are one of the most commonly used foundations in offshore structures. When a raft foundation alone does not satisfy the design requirements, the addition of piles may improve both the ultimate load capacity and the settlement performance of the raft. In this paper......, the behavior of a piled raft on undrained soil is studied based on a series of parametric studies on the average and differential settlement of piled raft using three-dimensional finite element analysis. The settlement behavior is found to be dependent on the number of piles and raft thickness....
Energy Technology Data Exchange (ETDEWEB)
Robert, J.; Raievski, V. [Commissariat a l' Energie Atomique, Paris (France). Centre d' Etudes Nucleaires; Hainzelin, J. [Chantiers de l' Atlantique (Penhoet-Loire), 75 - Paris (France)
1959-07-01
The programme of the high flux laboratory pile EL3 was laid down in october 1954. It is a heavy-water moderated and cooled pile. The fuel rods are of uranium metal with 1.6 per cent - 2 per cent of molybdenum, with aluminium canning. The maximum thermal flux in the moderator is 10{sup 14} n/cm{sup 2}/s. Studies began in january 1955, construction in may 1955, and the first divergence took place in July 1957. This report gives a general description of the pile and its adjacent buildings, the physical study of the pile, and certain technological studies carried out for the construction of EL3. (author) [French] Le programme de la pile laboratoire a haut flux EL3, a ete fixe en octobre 1954. C'est une pile moderee et refroidie a l'eau lourde. Les barres de combustible sont en uranium metal a 1,6 pour cent - 2 pour cent de molybdene, gainees a l'aluminium. Le flux thermique maximum dans le moderateur est de 10{sup 14} n/cm{sup 2}/s. Les etudes ont commence en janvier 1955, la construction en mai 1955, la premiere divergence a eu lieu en juillet 1957. On trouvera dans ce rapport, une description generale de la pile et de ses batiments annexes, l'etude physique de la pile et un certain nombre d'etudes technologiques executees pour la construction d'EL3. (auteur)
The Effects of Time on Soil Behaviour and Pile Capacity
DEFF Research Database (Denmark)
Augustesen, Anders
When designing pile foundations, static design equations, pile driving formulae, static loading tests or stress wave analyses can be employed to estimate the axial capacity of single piles. Both laboratory and field tests show that soil exhibits time-dependent behaviour. An important result...... is that soil gains additional strength and stiffness with time due to time-dependent processes such as ageing. Similarly, results show that the capacity of piles increases, to a certain extent, with time after installation due to time-dependent processes in the soil. However, most design methods do not take...... this into account. This implies that the design methods used today do not in general make use of the full capacity of piles. This thesis is based on a number of scientific papers and reports that deal with elements of pile design and time effects in soils in general. With regard to pile design, focus is placed...
Torsion sensing based on patterned piezoelectric beams
Cha, Youngsu; You, Hangil
2018-03-01
In this study, we investigated the sensing characteristics of piezoelectric beams under torsional loads. We used partially patterned piezoelectric beams to sense torsion. In particular, the piezoelectric patches are located symmetrically with respect to the line of the shear center of the beam. The patterned piezoelectric beam is modeled as a slender beam, and its electrical responses are obtained by piezoelectric electromechanical equations. To validate the modeling framework, experiments are performed using a setup that forces pure torsional deformation. Three different geometric configurations of the patterned piezoelectric layer are used for the experiments. The frequency and amplitude of the forced torsional load are systematically varied in order to study the behavior of the piezoelectric sensor. Experimental results demonstrate that two voltage outputs of the piezoelectric beam are approximately out of phase with identical amplitude. Moreover, the length of the piezoelectric layers has a significant influence on the sensing properties. Our theoretical predictions using the model support the experimental findings.
Full size testing of sheet pile walls
Kuilen, J.W.G. van de; Linden, M.L.R. van der; Katsma, H.; Stolle, P.
1996-01-01
Azobé (Lophira alata) is widely used in timber sheet pile walls in the Netherlands. The boards in these walls are coupled and therefore load-sharing can be expected. A simulation model based on the finite element method DIANA (DIANA, 1992) was developed and load-sharing could be calculated. To check
The Use of Tactile Sensors and PIV Analysis for Understanding the Bearing Mechanism of Pile Groups.
You, Zhijia; Chen, Yulong
2018-02-06
Model tests were carried out in dry silica sand under pile loading and visualizing observation to investigate the behavior of a pile group. The pile group consisted of nine cylindrical model piles of 40 mm in diameter in most tests or three rectangular parallelepiped model piles in the visualizing observation. Pile spacings of 200 mm and 100 mm between pile centers were used in the models. Tactile sensors were installed to measure the pressure distribution in the ground and colored sand layer with particle image velocimetry (PIV) analysis to reveal the ground deformation in addition to strain gauges inside the model piles to investigate the interaction among group piles. The tests results showed that a narrower spacing between piles resulted in a wider affected area of the ground and the interaction was more significant below the tips.
Interesting Developments in Testing Methods Applied to Foundation Piles
Sobala, Dariusz; Tkaczyński, Grzegorz
2017-10-01
Both: piling technologies and pile testing methods are a subject of current development. New technologies, providing larger diameters or using in-situ materials, are very demanding in terms of providing proper quality of execution of works. That concerns the material quality and continuity which define the integral strength of pile. On the other side we have the capacity of the ground around the pile and its ability to carry the loads transferred by shaft and pile base. Inhomogeneous nature of soils and a relatively small amount of tested piles imposes very good understanding of small amount of results. In some special cases the capacity test itself form an important cost in the piling contract. This work presents a brief description of selected testing methods and authors remarks based on cooperation with Universities constantly developing new ideas. Paper presents some experience based remarks on integrity testing by means of low energy impact (low strain) and introduces selected (Polish) developments in the field of closed-end pipe piles testing based on bi-directional loading, similar to Osterberg idea, but without sacrificial hydraulic jack. Such test is suitable especially when steel piles are used for temporary support in the rivers, where constructing of conventional testing appliance with anchor piles or kentledge meets technical problems. According to the author’s experience, such tests were not yet used on the building site but they bring a real potential especially, when the displacement control can be provided from the river bank using surveying techniques.
Hsu, Shu-Wei
2010-01-01
We present a method for directly modeling piles of objects in multi-body simulations. Piles of objects represent some of the more interesting, but also most time-consuming portion of simulation. We propose a method for reducing computation in many of these situations by explicitly modeling the piles that the objects may form into. By modeling pile behavior rather than the behavior of all individual objects, we can achieve realistic results in less time, and without directly modeling the frictional component that leads to desired pile shapes. Our method is simple to implement and can be easily integrated with existing rigid body simulations. We observe notable speedups in several rigid body examples, and generate a wider variety of piled structures than possible with strict impulse-based simulation. © 2010 ACM.
Wang, Shibo; Niu, Chengchao
2016-01-01
In this work, the plane-on-plane torsional fretting tribological behavior of polytetrafluoroethylene (PTFE) was studied. A model of a rigid, flat-ended punch acting on an elastic half-space was built according to the experimental conditions. The results indicate that the shape of T-θ curves was influenced by both the torsional angle and the normal load. The torsion friction torque and wear rate of PTFE exponentially decreased when the torsion angle rose. The torsional torque increased from 0.025 N·m under a normal load of 43 N to 0.082 N·m under a normal load of 123 N. With sequentially increasing normal load, the value of torque was maintained. With rising normal load, the wear mass loss of PTFE disks was increased and the wear rate was decreased. Good agreement was found with the calculated torque according to the model and the experimental torque except for that under a normal load of 163 N. The difference under a normal load of 163 N was caused by the coefficient of friction. Usually the coefficient of friction of a polymer decreases with increasing normal load, whereas a constant coefficient of friction was applied in the model.
Wang, Shibo; Niu, Chengchao
2016-01-01
In this work, the plane-on-plane torsional fretting tribological behavior of polytetrafluoroethylene (PTFE) was studied. A model of a rigid, flat-ended punch acting on an elastic half-space was built according to the experimental conditions. The results indicate that the shape of T–θ curves was influenced by both the torsional angle and the normal load. The torsion friction torque and wear rate of PTFE exponentially decreased when the torsion angle rose. The torsional torque increased from 0.025 N·m under a normal load of 43 N to 0.082 N·m under a normal load of 123 N. With sequentially increasing normal load, the value of torque was maintained. With rising normal load, the wear mass loss of PTFE disks was increased and the wear rate was decreased. Good agreement was found with the calculated torque according to the model and the experimental torque except for that under a normal load of 163 N. The difference under a normal load of 163 N was caused by the coefficient of friction. Usually the coefficient of friction of a polymer decreases with increasing normal load, whereas a constant coefficient of friction was applied in the model. PMID:26799324
International Nuclear Information System (INIS)
Robert, J.; Raievski, V.
1959-01-01
The programme of the high flux laboratory pile EL3 was laid down in october 1954. It is a heavy-water moderated and cooled pile. The fuel rods are of uranium metal with 1.6 per cent - 2 per cent of molybdenum, with aluminium canning. The maximum thermal flux in the moderator is 10 14 n/cm 2 /s. Studies began in january 1955, construction in may 1955, and the first divergence took place in July 1957. This report gives a general description of the pile and its adjacent buildings, the physical study of the pile, and certain technological studies carried out for the construction of EL3. (author) [fr
Lateral resistance of piles near vertical MSE abutment walls.
2013-03-01
Full scale lateral load tests were performed on eight piles located at various distances behind MSE walls. The objective of the testing was to determine the effect of spacing from the wall on the lateral resistance of the piles and on the force induc...
Visualization of soil arching in flexible piled embankments
Indian Academy of Sciences (India)
Abstract. Piled embankments rely on soil arching, but, when geogrid reinforce- ments 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 ...
Assessment of Time Functions for Piles Driven in Clay
DEFF Research Database (Denmark)
Augustesen, Anders; Andersen, Lars; Sørensen, Carsten Steen
The vertical bearing capacity of piles situated in clay is studied with regard to the long-term set-up. A statistical analysis is carried out on the basis of data from numerous static loading tests. The database covers a wide range of both soil and pile properties, which ensures a general...
Visualization of soil arching in flexible piled embankments
Indian Academy of Sciences (India)
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 ...
Pile foundation of nuclear power plant structures
International Nuclear Information System (INIS)
Jurkiewicz, W.J.; Thomaz, E.; Rideg, P.; Girao, M.
1978-01-01
The subject of pile foundation used for nuclear power plant structures, considering the experience gained by the designers of the Angra Nuclear Power Plant, Units 2 and 3 in Brazil is dealt with. The general concept of the pile foundations, including types and execution of the piles, is described briefly. Then the two basic models, i.e. the static model and the dynamic one, used in the design are shown, and the pertinent design assumptions as related to the Angra project are mentioned. The criteria which established the loading capacity of the piles are discussed and the geological conditions of the Angra site are also explained briefly, justifying the reasons why pile foundations are necessary in this project. After that, the design procedures and particularly the tools - i.e. the computer programs - are described. It is noted that the relatively simple but always time consuming job of loading determination calculations can be computerized too, as it was done on this project through the computer program SEASA. The interesting aspects of soil/structure interaction, applicable to static models, are covered in detail, showing the theoretical base wich was used in the program PILMAT. Then the advantage resulting from computerizing of the job of pile reinforcement design are mentioned, describing briefly the jobs done by the two special programs PILDES and PILTAB. The point is stressed that the effort computerizing the structural design of this project was not so much due to the required accuracy of the calculations, but mainly due to the need to save on the design time, as to allow to perform the design task within the relatively tight time schedule. A conclusion can be drawn that design of pile foundations for nuclear power plant structures is a more complex task than the design of bearing type of foundation for the same structures, but that the task can be always made easier when the design process can be computerized. (Author)
Modelling Pile Installation Effects : A Numerical Approach
Engin, H.K.
2013-01-01
One of the most traditional methods for supporting structures resting on soft soils is the use of piles. They generally work by transferring the loads to deeper soil layers, which can provide sufficient bearing capacity when mobilised. This type of foundations has been commonly used throughout the
Directory of Open Access Journals (Sweden)
al-Omari Raid R.
2017-01-01
Full Text Available Piles are often used in groups, and the behavior of pile groups under the applied loads is generally different from that of single pile due to the interaction of neighboring piles, therefore, one of the main objectives of this paper is to investigate the influence of pile group (bearing capacity, load transfer sharing for pile shaft and tip in comparison to that of single piles. Determination of the influence of load transfer from the pile group to the surrounding soil and the mechanism of this transfer with increasing the load increment on the tip and pile shaft for the soil in saturated and unsaturated state (when there is a negative pore water pressure. Different basic properties are used that is (S = 90%, γd = 15 kN / m3, S = 90%, γd = 17 kN / m3 and S = 60%, γd =15 kN / m3. Seven model piles were tested, these was: single pile (compression and pull out test, 2×1, 3×1, 2×2, 3×2 and 3×3 group. The stress was measured with 5 cm diameter soil pressure transducer positioned at a depth of 5 cm below the pile tip for all pile groups. The measured stresses below the pile tip using a soil pressure transducer positioned at a depth of 0.25L (where L is the pile length below the pile tip are compared with those calculated using theoretical and conventional approaches. These methods are: the conventional 2V:1H method and the method used the theory of elasticity. The results showed that the method of measuring the soil stresses with soil pressure transducer adopted in this study, gives in general, good results of stress transfer compared with the results obtained from the theoretical and conventional approaches.
Gallbladder torsion. Case report
DEFF Research Database (Denmark)
Brasso, K; Rasmussen, O V
1991-01-01
Gallbladder torsion is a rare surgical emergency occurring primarily in elderly women. The anatomical background is a variation in the attachment of the gallbladder to the inferior margin of the liver. Increasing life span will probably lead to an increasing number of cases, and gallbladder torsion...
Energy Technology Data Exchange (ETDEWEB)
Fresneda, R., E-mail: rodrigo.fresneda@ufabc.edu.br [Universidade Federal do ABC (UFABC), Santo Andre, SP (Brazil); Baldiotti, M.C.; Pereira, T.S., E-mail: baldiotti@uel.br, E-mail: tspereira@uel.br [Universidade Estadual de Londrina (UEL), Londrina, PR (Brazil). Departamento de Fisica
2015-06-15
We propose a gauge-invariant model of propagating torsion which couples to the Maxwell field and to charged particles. As a result, we have an Abelian gauge-invariant action leading to a theory with nonzero torsion consistent with available experimental data, which can be used to establish a lower bound for our new coupling parameter. (author)
Directory of Open Access Journals (Sweden)
Yu-Hui Huang
2006-09-01
Conclusion: Splenic torsion is a rare cause of acute abdominal pain during pregnancy or postpartum, and the symptoms vary depending on the degree of torsion. Early involvement of many complementary specialty services enabled early recognition of this rare entity and timely definitive treatment.
20051655 - Petronas, Capacity of Driven Piles Offshore Malaysia
DEFF Research Database (Denmark)
Augustesen, Anders; Andersen, Lars
This document is the third of four notes concerning the vertical capacity of piles. It includes an assessment of the effect of previous static load testing upon the measured capacity, i.e. preshearing effects....
The influence of connecting pile cap-column in the mechanisms of break in the two pile caps
Directory of Open Access Journals (Sweden)
A. C. MESQUITA
Full Text Available Abstract The paper analyzes the two pile caps with partially embedded socket and subject a center load. Three models were experimentally tested, varying the type of conformation of the column and walls of the socket, with a smooth, the other rough, and a monolithic two pile cap, used for reference. The roughening of the column-socket interface was examined with the aim of verifying the difference of the distribution of compressive and tensile stresses in the strut an tie model used for design. The experimental test to show that the two pile caps with conformation rough of the column and walls of the socket, support more load in comparison with two pile caps with smooth of the column and walls of the socket. Both however underperformed the monolithic two pile cap, with values of 66% and 36% respectively.
Directory of Open Access Journals (Sweden)
Saeed Ghaffarpour Jahromi
2016-06-01
Full Text Available Capacity of pile group is the summation of the individual piles capacity with influence of spacing between the piles. Pile groups usually have the same length, so if the spacing between piles is too close, the zones of stress around the pile will overlap and the ultimate load of the group is less than the sum of the individual pile capacities especially in the case of friction piles, where the efficiency of pile group is much less. In this research the optimization of bearing capacity and unsymmetrical settlement of cap in the vertical pile group using genetic algorithm were studied. Friction pile in granular soil, with different length and arrangement were investigated to find the best performance of the group for the axial stiffness, bearing capacity and unsymmetrical settlement. The criterion of optimization is the volume of concrete needs for piles and cap. Two patterns of 5×5 pile groups (row variation and squared variation are studied in this research. The analysis of pile group to find bearing capacity was conducted using the finite element software (Fb-pier and for optimization used evolutionary genetic algorithm method.
Torsional Strengthening of RC Beams Using GFRP Composites
Patel, Paresh V.; Jariwala, Vishnu H.; Purohit, Sharadkumar P.
2016-09-01
Fiber reinforced polymer as an external reinforcement is used extensively for axial, flexural and shear strengthening in structural systems. The strengthening of members subjected to torsion is recently being explored. The loading mechanism of beams located at the perimeter of buildings which carry loads from slabs, joists and beams from one side of the member generates torsion that are transferred from the beams to the columns. In this work an experimental investigation on the improvement of the torsional resistance of reinforced concrete beams using Glass Fiber Reinforced Polymer (GFRP) is presented. Total 24 RC beams have been cast in this work. Ten beams of dimension 150 mm × 150 mm × 1300 mm are subjected to pure torsion while fourteen beams of 150 mm × 150 mm × 1700 mm are subjected to combined torsion and bending. Two beams in each category are designated as control specimen and remaining beams are strengthened by GFRP wrapping of different configurations. Pure torsion on specimens is applied using specially fabricated support mechanism and universal testing machine. For applying combined torsion and bending a loading frame and test set up are fabricated. Measurements of angle of twist at regular interval of torque, torsion at first crack, and ultimate torque, are obtained for all specimens. Results of different wrapping configurations are compared for control and strengthened beams to suggest effective GFRP wrapping configuration.
FLEXURAL, TORSIONAL AND DISTORTIONAL BUCKLING OF ...
African Journals Online (AJOL)
neutral equilibrium of axially compressed single-cell box column with deformable cross-sections. The study ... FLEXURAL, TORSIONAL AND DISTORTIONAL BUCKLING OF SINGLE-CELL THIN-WALLED BOX COLUMNS cr. P : Critical buckling load. S: ... and v of a thin-walled closed structure in series form as follows: (1).
Bilmont, A; Palierne, S; Verset, M; Swider, P; Autefage, A
2015-01-01
The number of locking screws required per fragment during bridging osteosynthesis in the dog has not been determined. The purpose of this study was to assess the survival of two constructs, with either two or three screws per fragment, under cyclic torsion. Ten-hole 3.5 mm stainless steel locking compression plates (LCP) were fixed 1 mm away from bone surrogates with a fracture gap of 47 mm using two bicortical locking screws (10 constructs) or three bicortical locking screws (10 constructs) per fragment, placed at the extremities of each LCP. Constructs were tested in cyclic torsion (range: 0 to +0.218 rad) until failure. The 3-screws constructs (29.65 ± 1.89 N.m/rad) were stiffer than the 2-screws constructs (23.73 ± 0.87 N.m/rad), and therefore, were subjected to a greater torque during cycling (6.05 ± 1.33 N.m and 4.88 ± 1.14 N.m respectively). The 3-screws constructs sustained a significantly greater number of cycles (20,700 ± 5,735 cycles) than the 2-screws constructs (15,600 ± 5,272 cycles). In most constructs, failure was due to screw damage at the junction of the shaft and head. The remaining constructs failed because of screw head unlocking, sometimes due to incomplete seating of the screw head prior to testing. Omitting the third innermost locking screw during bridging osteosynthesis led to a reduction in fatigue life of 25% and construct stiffness by 20%. Fracture of the screws is believed to occur sequentially, starting with the innermost screw that initially shields the other screws.
Energy Technology Data Exchange (ETDEWEB)
Kysela, Jan [Research Centre Rez, Hlavni 130, 250 68 Husinec-Rez (Czech Republic); Entler, Slavomir, E-mail: slavomir.entler@cvrez.cz [Research Centre Rez, Hlavni 130, 250 68 Husinec-Rez (Czech Republic); Vsolak, Rudolf; Klabik, Tomas [Research Centre Rez, Hlavni 130, 250 68 Husinec-Rez (Czech Republic); Zlamal, Ondrej [CEZ, Duhova 2/1444, 140 53 Praha 4 (Czech Republic); Bellin, Boris; Zacchia, Francesco [Fusion for Energy, Josep Pla, 2, Torres Diagonal Litoral B3, 08019 Barcelona (Spain)
2015-10-15
Highlights: • Irradiated thermal fatigue testing of the ITER primary first wall mock-ups. • Cyclic heat flux of 0.5 MW/m{sup 2} in the neutron field of the nuclear reactor core. • 17,040 thermal cycles. • Radiation damage in the range of 0.41–1.17 dpa depending on the material. - Abstract: The TW3 in-pile rig enabled the thermal fatigue testing of ITER primary first wall mock-ups in the core of the nuclear reactor. This experiment investigated the neutron irradiation influence on the design performance under high heat flux testing. A thermal flux of 0.5 MW/m{sup 2} in the neutron field of the core of the LVR-15 nuclear reactor was applied. Within the scope of the tests with simultaneous neutron irradiation, the TW3 rig reached a record of 17,040 thermal cycles with the radiation damage in the range of 0.41–1.17 dpa depending on the material. Even after a high number of thermal cycles, while being irradiated by neutrons, no damage of the tested mock-ups was visually observed. Further testing and analysis will follow in the Forschungszentrum Juelich.
Lateral response of pile foundations in liquefiable soils
Directory of Open Access Journals (Sweden)
Asskar Janalizadeh
2015-10-01
Full Text Available Liquefaction has been a main cause of damage to civil engineering structures in seismically active areas. The effects of damage of liquefaction on deep foundations are very destructive. Seismic behavior of pile foundations is widely discussed by many researchers for safer and more economic design purposes. This paper presents a pseudo-static method for analysis of piles in liquefiable soil under seismic loads. A free-field site response analysis using three-dimensional (3D numerical modeling was performed to determine kinematic loads from lateral ground displacements and inertial loads from vibration of the superstructure. The effects of various parameters, such as soil layering, kinematic and inertial forces, boundary condition of pile head and ground slope, on pile response were studied. By comparing the numerical results with the centrifuge test results, it can be concluded that the use of the p-y curves with various degradation factors in liquefiable sand gives reasonable results.
Analysis of static and dynamic pile-soil-jacket behaviour
Energy Technology Data Exchange (ETDEWEB)
Azadi, Mohammad Reza Emami
1998-12-31
In the offshore industry, recent extreme storms, severe earthquakes and subsidence of the foundation of jacket platforms have shown that new models and methods must take into account the jacket- pile-soil foundation interaction as well as the non-linear dynamic performance/loading effects. This thesis begins with a review of the state of art pile-soil interaction model, recognizing that most existing pile-soil models have been established based on large diameter pile tests on specific sites. The need for site independent and mechanistic pile-soil interaction models led to the development of new (t-z) and (p-y) disk models. These are validated using the available database from recent large diameter pile tests in the North Sea and Gulf of Mexico. The established static disk models are applied for non-linear static analysis of the jacket-pile-soil system under extreme wave loading. Dynamic pile-soil interaction is studied and a new disk-cone model is developed for the non-linear and non-homogeneous soils. This model is applied to both surface and embedded disks in a soil layer with non-linear properties. Simplified non-linear as well as more complex analysis methods are used to study the dynamic response of the jacket platform under extreme sea and seismic loading. Ductility spectra analysis is introduced and used to study the dynamic performance of the jacket systems near collapse. Case studies are used to illustrate the effects of structural, foundation failure characteristics as well as dynamic loading effects on the overall performance of the jacket-pile-soil systems near ultimate collapse. 175 refs., 429 figs., 70 tabs.
Energy Technology Data Exchange (ETDEWEB)
Bassan, Massimo [Dipartimento di Fisica, Università di Roma Tor Vergata, and INFN, Sezione di Roma Tor Vergata, I-00133 Roma (Italy); De Marchi, Fabrizio, E-mail: fabrizio.demarchi@roma2.infn.it [Dipartimento di Fisica, Università di Roma Tor Vergata, and INFN, Sezione di Roma Tor Vergata, I-00133 Roma (Italy); Marconi, Lorenzo [Dipartimento di Fisica ed Astronomia, Università degli Studi di Firenze, and INFN, Sezione di Firenze (Italy); Pucacco, Giuseppe [Dipartimento di Fisica, Università di Roma Tor Vergata, and INFN, Sezione di Roma Tor Vergata, I-00133 Roma (Italy); Stanga, Ruggero [Dipartimento di Fisica ed Astronomia, Università degli Studi di Firenze, and INFN, Sezione di Firenze (Italy); Visco, Massimo [IAPS-INAF, and INFN, Sezione di Roma Tor Vergata, I-00133 Roma (Italy)
2013-10-01
We present an analysis of the motion of a simple torsion pendulum and we describe how, with straightforward extensions to the usual basic dynamical model, we succeed in explaining some unexpected features we found in our data, like the modulation of the torsion mode at a higher frequency and the frequency splitting of the swinging motion. Comparison with observed values yields estimates for the misalignment angles and other parameters of the model.
International Nuclear Information System (INIS)
Denardo, G.; Spallucci, E.
1985-07-01
We study pregeometry in the framework of a Poincare gauge field theory. The Riemann-Cartan space-time is shown to be an ''effective geometry'' for this model in the low energy limit. By using Heat Kernel techniques we find the induced action for curvature and torsion. We obtain in this way the usual Einstein-Hilbert action plus an axial Maxwell term describing the propagation of a massless, axial vector torsion field. (author)
Torsional Behavior of Axonal Microtubule Bundles
Lazarus, Carole; Soheilypour, Mohammad; Mofrad, Mohammad R.K.
2015-01-01
Axonal microtubule (MT) bundles crosslinked by microtubule-associated protein (MAP) tau are responsible for vital biological functions such as maintaining mechanical integrity and shape of the axon as well as facilitating axonal transport. Breaking and twisting of MTs have been previously observed in damaged undulated axons. Such breaking and twisting of MTs is suggested to cause axonal swellings that lead to axonal degeneration, which is known as “diffuse axonal injury”. In particular, overstretching and torsion of axons can potentially damage the axonal cytoskeleton. Following our previous studies on mechanical response of axonal MT bundles under uniaxial tension and compression, this work seeks to characterize the mechanical behavior of MT bundles under pure torsion as well as a combination of torsional and tensile loads using a coarse-grained computational model. In the case of pure torsion, a competition between MAP tau tensile and MT bending energies is observed. After three turns, a transition occurs in the mechanical behavior of the bundle that is characterized by its diameter shrinkage. Furthermore, crosslink spacing is shown to considerably influence the mechanical response, with larger MAP tau spacing resulting in a higher rate of turns. Therefore, MAP tau crosslinking of MT filaments protects the bundle from excessive deformation. Simultaneous application of torsion and tension on MT bundles is shown to accelerate bundle failure, compared to pure tension experiments. MAP tau proteins fail in clusters of 10–100 elements located at the discontinuities or the ends of MT filaments. This failure occurs in a stepwise fashion, implying gradual accumulation of elastic tensile energy in crosslinks followed by rupture. Failure of large groups of interconnecting MAP tau proteins leads to detachment of MT filaments from the bundle near discontinuities. This study highlights the importance of torsional loading in axonal damage after traumatic brain injury
Wang, W. C.; Lin, D. G.
2015-12-01
This study investigates the bearing capacities and mechanical behaviors of pile foundation installed on the seabed of wind farm near Chang-Hua coast of western Taiwan for the supporting structure of offshore wind turbine. A series of three-dimensional (3-D) numerical modeling of pile foundation subjected to various types of combined loading were carried out using Plaix-3D finite element program to investigate the interactive behaviors between soil and pile. In the numerical modeling, pile diameter, pile length and pile spacing were selected as design parameters to inspect their effects on the bearing capacities and deformation behaviors of the pile foundation. For a specific design parameter combination, one can obtain the corresponding loading-displacement curve, various ultimate bearing capacities, V-H (Vertical-Horizontal combined loading) ultimate bearing capacity envelope, and p-ycurve of pile foundation. Numerical results indicate that: (1) Large displacement and plastic points at ultimate state mostly distribute and concentrate in the topsoil of seabed and around pile head. (2) The soil resistance on the soil-pile interface is ascending with the increases of depth, pile diameter and pile length. (3) The vertical and horizontal bearing capacities of pile group increase significantly with the increase of pile diameter. (4) The vertical and bending moment capacities of pile group increase greatly with the increase of pile length whereas the horizontal capacity is almost insensitive to pile length. (5) The bending moment of pile is highly influenced by the pile spacing. (6) For different design parameters, the shape of ultimate bearing capacity envelopes of pile group on V-H plane is similar while the envelopes will expand as the design parameters increase. For different loading levels of bending moment, the envelopes on V-H plane will contract gradually as the bending moment loading increasing.
International Nuclear Information System (INIS)
Raievski, V.; Sautiez, B.
1959-01-01
The report describes a pile designed to measure the absorption of fuel slugs. The pile is of graphite and comprises a central section composed of uranium rods in a regular lattice. RaBe sources and BF 3 counters are situated on either side of the center. A given uranium charge is compared with a specimen charge of about 560 kg, and the difference in absorption between the two noted. The sensitivity of the equipment will detect absorption variations of about a few ppm boron (10 -6 boron per gr. of uranium) or better. (author) [fr
Characterizing hand-piled fuels
Clinton S. Wright; Paige C. Eagle; Cameron S. Balog
2010-01-01
Land managers throughout the West pile and burn surface fuels to mitigate fire hazard in dry forests. Whereas piling was historically conducted with heavy machinery following commercial harvesting operations, land managers are increasingly prescribing the use of hand piling and burning to treat surface fuels created by thinning and brush cutting. An estimate of the...
Three-dimensional analysis of two-pile caps
Directory of Open Access Journals (Sweden)
T.E.T. Buttignol
Full Text Available This paper compares the results between a non-linear three-dimensional numerical analysis of pile caps with two piles and the experimental study conducted by Delalibera. It is verified the load-carrying capacity, the crack pattern distribution, the principal stress in concrete and steel, the deflection and the fracture of the pile cap. The numerical analysis is executed with the finite-element software ATENA 3D, considering a perfect bond between concrete and steel. The numerical and experimental results are presented and have demonstrated a good approximation, reasserting the results of the experimental model and corroborating the theory.
The Influence of Time on Bearing Capacity of Driven Piles
DEFF Research Database (Denmark)
Jensen, J. Lysebjerg; Augustesen, A.; Sørensen, Carsten S.
2004-01-01
In Danish engineering practice, one of the ways to determine the ultimate bearing capacity of an axially loaded pile is by means of geostatic formulas. In the equation describing the contribution from the shaft friction to the total bearing capacity for piles located entirely or partly in clay......, a regeneration factor appears. The regeneration factor accounts for effects of dissipation of pore pressure due to pile driving and true time effects such as ageing on the ultimate bearing capacity. Normally the factor is 0.4 but in this paper, the influence of the undrained shear strength and time...
Effects of Diameter on Initial Stiffness of P-Y Curves for Large-Diameter Piles in Sand
DEFF Research Database (Denmark)
Sørensen, Søren Peder Hyldal; Ibsen, Lars Bo; Augustesen, Anders Hust
2010-01-01
-pile interaction. Hence, a modified expression for the p-y curves for statically loaded piles in sand is proposed in which the initial slope of the p-y curves depends on the depth below the soil surface, the pile diameter and the internal angle of friction. The evaluation is based on three-dimensional numerical...
Fermi, Enrico
The Patent contains an extremely detailed description of an atomic pile employing natural uranium as fissile material and graphite as moderator. It starts with the discussion of the theory of the intervening phenomena, in particular the evaluation of the reproduction or multiplication factor, K, that is the ratio of the number of fast neutrons produced in one generation by the fissions to the original number of fast neutrons, in a system of infinite size. The possibility of having a self-maintaining chain reaction in a system of finite size depends both on the facts that K is greater than unity and the overall size of the system is sufficiently large to minimize the percentage of neutrons escaping from the system. After the description of a possible realization of such a pile (with many detailed drawings), the various kinds of neutron losses in a pile are depicted. Particularly relevant is the reported "invention" of the exponential experiment: since theoretical calculations can determine whether or not a chain reaction will occur in a give system, but can be invalidated by uncertainties in the parameters of the problem, an experimental test of the pile is proposed, aimed at ascertaining if the pile under construction would be divergent (i.e. with a neutron multiplication factor K greater than 1) by making measurements on a smaller pile. The idea is to measure, by a detector containing an indium foil, the exponential decrease of the neutron density along the length of a column of uranium-graphite lattice, where a neutron source is placed near its base. Such an exponential decrease is greater or less than that expected due to leakage, according to whether the K factor is less or greater than 1, so that this experiment is able to test the criticality of the pile, its accuracy increasing with the size of the column. In order to perform this measure a mathematical description of the effect of neutron production, diffusion, and absorption on the neutron density in the
Seismic Dynamic Damage Characteristics of Vertical and Batter Pile-supported Wharf Structure Systems
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Li Jiren
2015-10-01
Full Text Available Considering a typical steel pipe pile-supported wharf as the research object, finite element analytical models of batter and vertical pile structures were established under the same construction site, service, and geological conditions to investigate the seismic dynamic damage characteristics of vertical and batter pile-supported wharf structures. By the numerical simulation and the nonlinear time history response analysis of structure system and the moment–axial force relation curve, we analyzed the dynamic damage characteristics of the two different structures of batter and vertical piles under different seismic ground motions to provide reasonable basis and reference for designing and selecting a pile-supported wharf structure. Results showed that the axial force of batter piles was dominant in the batter pile structure and that batter piles could effectively bear and share seismic load. Under the seismic ground motion with peak ground acceleration (PGA of 350 Gal and in consideration of the factors of the design requirement of horizontal displacement, the seismic performance of the batter pile structure was better than that of the vertical pile structure. Under the seismic ground motion with a PGA of 1000 Gal, plastic failure occurred in two different structures. The contrastive analysis of the development of plastic damage and the absorption and dissipation for seismic energy indicated that the seismic performance of the vertical pile structure was better than that of the batter pile structure.
Mechanical origins of rightward torsion in early chick brain development
Chen, Zi; Guo, Qiaohang; Dai, Eric; Taber, Larry
2015-03-01
During early development, the neural tube of the chick embryo undergoes a combination of progressive ventral bending and rightward torsion. This torsional deformation is one of the major organ-level left-right asymmetry events in development. Previous studies suggested that bending is mainly due to differential growth, however, the mechanism for torsion remains poorly understood. Since the heart almost always loops rightwards that the brain twists, researchers have speculated that heart looping affects the direction of brain torsion. However, direct evidence is lacking, nor is the mechanical origin of such torsion understood. In our study, experimental perturbations show that the bending and torsional deformations in the brain are coupled and that the vitelline membrane applies an external load necessary for torsion to occur. Moreover, the asymmetry of the looping heart gives rise to the chirality of the twisted brain. A computational model and a 3D printed physical model are employed to help interpret these findings. Our work clarifies the mechanical origins of brain torsion and the associated left-right asymmetry, and further reveals that the asymmetric development in one organ can induce the asymmetry of another developing organ through mechanics, reminiscent of D'Arcy Thompson's view of biological form as ``diagram of forces''. Z.C. is supported by the Society in Science - Branco Weiss fellowship, administered by ETH Zurich. L.A.T acknowledges the support from NIH Grants R01 GM075200 and R01 NS070918.
An experimental study on mechanical properties of fiber-reinforced concrete of energy piles
Directory of Open Access Journals (Sweden)
Songying Zhao
2017-07-01
Full Text Available The technology of energy piles for heat storage involves turning the concrete piles buried beneath the ground into a part of the ground-source heat pump system and burying the heat-transfer tubes in the foundation piles, which are regarded as heat transfer wells. The heat transfer tubes are embedded in the concrete foundation piles, destroying the mechanical bearing capacity of the piles and damaging the safety of the buildings. Thus, considering the structural stability and the degree of heat transfer of concrete piles, as well as the selection of material for the foundation piles, the mixing ratio of the material of the energy piles is experimentally studied by the orthogonal method. The optimum mixing ratio of the energy pile is thus obtained. A concrete test block is used to conduct a static load test and splitting test to verify the mixing ratio of the concrete of the energy pile. The results show that steel fiber can be used to enhance the bearing capacity of the storage pile as a reinforcement material. Under a reasonable ratio, the reinforced pile can absolutely meet the original design requirements. Ordinary Portland cement or composite Portland cement can be used as cementitious materials for energy piles. Through an experiment, it is proved that the composite Portland cement can better meet the requirements of the concrete foundation piles than the cementitious material. As thermal conductivity materials, the addition of industrial graphite and scrap copper slag can improve the thermal conductivity of the pile, but it can also reduce the mechanical properties of the pile. It is necessary to control it in a certain range and not to add a large amount of graphite just to improve the thermal conductivity.
Soil-Pile Interaction in the Pile Vertical Vibration Based on Fictitious Soil-Pile Model
Directory of Open Access Journals (Sweden)
Guodong Deng
2014-01-01
Full Text Available By introducing the fictitious soil-pile model, the soil-pile interaction in the pile vertical vibration is investigated. Firstly, assuming the surrounding soil of pile to be viscoelastic material and considering its vertical wave effect, the governing equations of soil-pile system subjected to arbitrary harmonic dynamic force are founded based on the Euler-Bernoulli rod theory. Secondly, the analytical solution of velocity response in frequency domain and its corresponding semianalytical solution of velocity response in time domain are derived by means of Laplace transform technique and separation of variables technique. Based on the obtained solutions, the influence of parameters of pile end soil on the dynamic response is studied in detail for different designing parameters of pile. Lastly, the fictitious soil-pile model and other pile end soil supporting models are compared. It is shown that the dynamic response obtained by the fictitious soil-pile model is among the dynamic responses obtained by other existing models if there are appropriate material parameters and thickness of pile end soil for the fictitious soil-pile model.
Embedded data collector (EDC) phase II load and resistance factor design (LRFD) : [summary].
2015-07-01
Piles that support bridge structures are designed for the specific site characteristics and loads : that the piles are expected to bear. In Florida, driven piles are monitored during installation : (dynamically tested) to assess resistance, com...
Mosna, Ricardo A.; Saa, Alberto
2005-11-01
We reexamine here the issue of consistency of minimal action formulation with the minimal coupling procedure (MCP) in spaces with torsion. In Riemann-Cartan spaces, it is known that a proper use of the MCP requires that the trace of the torsion tensor be a gradient, Tμ=∂μθ, and that the modified volume element τθ=eθ√g dx1∧⋯∧dxn be used in the action formulation of a physical model. We rederive this result here under considerably weaker assumptions, reinforcing some recent results about the inadequacy of propagating torsion theories of gravity to explain the available observational data. The results presented here also open the door to possible applications of the modified volume element in the geometric theory of crystalline defects.
PROCESS DIAGRAMS FOR INSTALLATION OF DRIVEN PILES IN PENETRATED WELLS
Directory of Open Access Journals (Sweden)
Kovalev Vladimir Aleksandrovich
2017-03-01
Full Text Available This article presents the main options of improved and newly devised designs and process diagrams for installation of foundations made of driven, or jack, piles in the penetrated wells with expanded shoe, mainly in weak wet (waterlogged and water-saturated soils. The article presents six options of process diagrams for installation of driven piles in penetrated wells, listing the main procedures: for well-compacted weak soils, for the case when the water ingress is excluded, for the case when it is necessary to increase the load-bearing capacity of pile's bearing face in the waterlogged soils, for the case when the load-bearing capacity of the pile shall be increased both for the end and for the sides, for the case when peat or other biogenous water-saturated soils are present at the bottom of the well, and for the case when there is no contracted zone nor practical possibility to ensure the stability of the walls. The proposed six options of process diagrams for installation of the driven piles in penetrated wells provide expansion of their area of application regarding the soil conditions, increase of load-bearing capacity, and possibility of using jack systems for driving the piles under conditions of dense urban development.
Higher Franz-Reidemeister torsion
Igusa, Kiyoshi
2002-01-01
The book is devoted to the theory of topological higher Franz-Reidemeister torsion in K-theory. The author defines the higher Franz-Reidemeister torsion based on Volodin's K-theory and Borel's regulator map. He describes its properties and generalizations and studies the relation between the higher Franz-Reidemeister torsion and other torsions used in K-theory: Whitehead torsion and Ray-Singer torsion. He also presents methods of computing higher Franz-Reidemeister torsion, illustrates them with numerous examples, and describes various applications of higher Franz-Reidemeister torsion, particularly for the study of homology of mapping class groups. Packed with up-to-date information, the book provides a unique research and reference tool for specialists working in algebraic topology and K-theory.
Isolated Fallopian Tube Torsion
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S. Kardakis
2013-01-01
Full Text Available Isolated torsion of the Fallopian tube is a rare gynecological cause of acute lower abdominal pain, and diagnosis is difficult. There are no pathognomonic symptoms; clinical, imaging, or laboratory findings. A preoperative ultrasound showing tubular adnexal masses of heterogeneous echogenicity with cystic component is often present. Diagnosis can rarely be made before operation, and laparoscopy is necessary to establish the diagnosis. Unfortunately, surgery often is performed too late for tube conservation. Isolated Fallopian tube torsion should be suspected in case of acute pelvic pain, and prompt intervention is necessary.
Torsional Moment Measurement on Bucket Wheel Shaft of Giant Machine
Directory of Open Access Journals (Sweden)
Jiří FRIES
2011-06-01
Full Text Available Bucket wheel loading at the present time (torsional moment on wheel shaft, peripheral cutting force is determined from electromotor incoming power or reaction force measured on gearbox hinge. Both methods together are weighted by steel construction absorption of driving units and by inertial forces of motor rotating parts. In the article is described direct method of the torsional moment measurement, which eliminates mentioned unfavourable impacts except absorption of steel construction of bucket wheel itself.
THE NEW STRUCTURE OF A PLATE-PILE FOUNDATION
Directory of Open Access Journals (Sweden)
SAMORODOV О. V.
2016-01-01
Full Text Available Raising of problem. In the construction of high-rise buildings with significant loads on foundations and bedding at the base of not rocky soils tend to use the most common pile foundation to reduce the deformation and correspond to regulations [1] on the maximum permissible deformation. Monitoring of the stress-strain state (SSS pile foundations constructed buildings shows the existing reserves of bearing capacity on the one hand - soil bases of the second group of limit states, on the other - the foundation of the first group of limit states by regulating the SSS foundation during construction and exploitation. Therefore, are increasingly using more progressive structure of foundations consisting of piles and of plate, as well as methods for their construction [2 - 10], however, in their design there are a number of disadvantages associated with the ambiguity of the application of methods for the calculation of such structures, which allows to do only partial conclusions and recommendations. Purpose. Is proposing the new structure of a plate-pile foundation, which overcomes the drawbacks of the existing design solutions and methods of consruction their, as well as is proposing an engineering method of a determination of basic parameters. Conclusion. Is proposes the new structure of a plate-pile foundation and the method of a determination of basic parameters his in the design of a soil base to the maximum permissible deformation Su buildings. Efficiency of application this type plate-pile foundation obtained by rational distribution resistance between a plate and piles, when under load from the building to the first work fully incorporated plate that allows maximum deformed for plate, and then the piles - due to of the hinge connection with the plate. Thus, depending on the maximum permissible deformation for buildings resistance of plate part of a full load of more than 50%, that significantly reduces the consumption of concrete.
2015-04-01
The overall goal of this project is the experimental evaluation and design of unfilled and concrete-filled FRP : composite piles for load-bearing in bridges. This report covers Task 6, FRP Composite Pile Axial Compression : Testing. : Hollow and conc...
Electrostatically actuated torsional resonant sensors and switches
Younis, Mohammad I.
2016-12-29
Embodiments in accordance of a torsional resonant sensor disclosure is configured to actuate a beam structure using electrostatic actuation with an AC harmonic load (e.g., AC and DC voltage sources) that is activated upon detecting a particular agent having a mass above a predefined level. In various embodiments, the beam structure may be different types of resonant structures that is at least partially coated or layered with a selective material.
Ihrke, Chris A. (Inventor); Parsons, Adam H. (Inventor); Mehling, Joshua S. (Inventor); Griffith, Bryan Kristian (Inventor)
2012-01-01
A torsion spring comprises an inner mounting segment. An outer mounting segment is located concentrically around the inner mounting segment. A plurality of splines extends from the inner mounting segment to the outer mounting segment. At least a portion of each spline extends generally annularly around the inner mounting segment.
Electrostatically suspended torsion pendulum
Willemenot, E.; Touboul, P.
2000-01-01
A torsion pendulum without a torsion wire has been designed and realized, in order to measure very weak forces. The arm of this torsion pendulum (5.40 g, 1.32×10-6 kg m2 of inertia) is electrostatically suspended. Its 6 degrees of freedom are controlled thanks to electrostatic forces, and capacitive position sensing with a noise spectral density between 10-10 and 10-13 m/√Hz . The torque noise spectral density is 1.3×10-14 Nm/√Hz around 0.05 Hz with a 1/√f increase at lower frequency, corresponding to 10-8 rad/s2/√Hz , and 2×10-10 ms-2/√Hz with a lever arm of 2 cm. The residual seismic noise limit the performances above 0.1 Hz. The free oscillating mode has a torsion stiffness of 5.14×10-8 Nm/rad and a Q of 217. This new instrument allows on ground experiments on very weak parasitic forces inside space accelerometers developed in ONERA, with a good representativeness. For example, it is possible to measure electrostatic stiffnesses with high resolution thanks to the low torque noise spectral density; the electrostatic damping phenomenon is also well seen as illustrated by the rather low Q. The instrument design and operation are described, the main performances are given, and the possibilities offered are discussed.
Testicular Torsion (For Parents)
... securing the testicles to the scrotum. If your son had a torsion that resulted in the loss of a testicle, it's important to let him know that he can still lead a normal life, just like anyone else. The loss of one testicle won't prevent a man from having normal sexual relations and is unlikely ...
Gallbladder torsion. Case report
DEFF Research Database (Denmark)
Brasso, K; Rasmussen, O V
1991-01-01
Gallbladder torsion is a rare surgical emergency occurring primarily in elderly women. The anatomical background is a variation in the attachment of the gallbladder to the inferior margin of the liver. Increasing life span will probably lead to an increasing number of cases, and gallbladder torsi...
African Journals Online (AJOL)
he had described a typical case in an 18 year old who later developed torsion of the contra-lateral testis and suffered ... he visited our hospital where an ultrasound scan was ordered, which was reported as showing an enlarged .... Mills S.E., Carter D., Reuter V.E., et al. Sternberg's diagnostic surgical pathology. 2004;4th.
International Nuclear Information System (INIS)
Aros, Rodrigo; Contreras, Mauricio
2006-01-01
In this work the Poincare-Chern-Simons and anti-de Sitter-Chern-Simons gravities are studied. For both, a solution that can be cast as a black hole with manifest torsion is found. Those solutions resemble Schwarzschild and Schwarzschild-AdS solutions, respectively
African Journals Online (AJOL)
are retractile and more mobility is at increased risk for torsion. An increased prevalence of carcinoma has also been reported.[1]. Case Report. A 72-year-old man presented with vague pain in the lower abdomen and scrotum. There was no history of trauma and he stated that the pain was severe in nature and had been ...
A Numerical Simulation of Base Shear Forces and Moments Exerted by Waves on Large Diameter Pile
Directory of Open Access Journals (Sweden)
You-liang Cheng
2017-01-01
Full Text Available To solve the problem of the dynamic variation of wave force diameter of pile foundation for offshore wind turbines, wave force and moment of large diameter pile foundation can be calculated. In this paper, simulation technique is used to calculate the wave force and moment of different large diameter pile foundation, and the base shear force and moment of the interval 20-degree phase angle are obtained by the base line of the pile. Under the action of a certain load, the complete stress variation of the pile foundation is obtained. According to the basic principle of diffraction theory, the process curve of large diameter pile, and analysis of wave force, diffraction force changes in a certain period of time interval. The results show that the wave after the large diameter pile formed around the vortex, large diameter pile base shear, and moment dynamic change is nonlinear in a complete cycle, the diameter of the pile increases by 0.5 m, and the wave force increases by about 5%, the results show that it provides certain reference value for the offshore pile foundation pile with large diameter primary site. Some significant results for practical application are discussed.
Directory of Open Access Journals (Sweden)
Yi Fan
2016-01-01
Full Text Available The purpose of the paper is to research the vertical bearing capacity and settlement idiosyncracies of prestressed concrete piles. In-situ experiments, which was carried out by anchor-pile beam counterforce device, and numerical analysis methods was adopted as research methods on 3 tested piles. Mohr-Coulomb model was employed as the constitutive model of soil mass and isotropic elastic damage model as the constitutive model of piles to analyze its yield functions. Furthermore, the basic idea of modelling large deformation problems was analyzed based on Finite Difference Method (FDM. The comparison results was obtained in the paper and it suggested that the simulated data is highly identical with the experimental ones. Load-settlement curve basically presents a quadratic function form.
International Nuclear Information System (INIS)
Takatsu, Hideyuki; Yamamoto, Masahiro; Shimizu, Masatsugu; Suzuki, Kazuo; Sonobe, Tadashi; Hayashi, Yuzo; Mizuno, Gen-ichiro.
1984-01-01
Torsional fatigue strength of the welded bellows was evaluated experimentally, aiming the application to a port of a fusion device. The welded bellows revealed elastic torsional buckling and spiral distorsion even under a small angle of torsion. Twisting load never leads the welded bellows to fracture easily so far as the angle of torsion is not excessively large, and the welded bellows has the torsional fatigue strength much larger than that expected so far. Two formulae were proposed to evaluate the stress of the welded bellows under the forced angle of torsion; shearing stress evaluation formula in the case that torsional buckling does not occur and the axial bending stress evaluation formula in the case that torsional buckling occurs. And the results of the torsional fatigue experiments showed that the former is reasonably conservative and simulates the actual behavior of the welded bellows better than the latter in the high cycle fatigue region and vice versa in the low cycle fatigue region from the viewpoint of the mechanical design. The present evaluation method of the torsional fatigue strength was applied to the welded bellows for the port of the JT-60 vacuum vessel and its structural integrity was confirmed under the design load condition. (author)
Use of geothermal piles combined with pile foundations
Directory of Open Access Journals (Sweden)
Ivan Kuzytskyi
2016-07-01
Full Text Available The possibility of use of geothermal piles in conditions of cold climate is considered. Full-scale experiment is conducted for using this technology in Kiev. Obtained results testify about a possibility for using the system in conditions of Ukraine, but this technology requires more detailed study and simulation of multiannual cycle of use of geothermal piles
Torsional Ratcheting Actuating System
Energy Technology Data Exchange (ETDEWEB)
BARNES,STEPHEN MATTHEW; MILLER,SAMUEL L.; RODGERS,M. STEVEN; BITSIE,FERNANDO
2000-01-24
A new type of surface micromachined ratcheting actuation system has been developed at the Microelectronics Development Laboratory at Sandia National Laboratories. The actuator uses a torsional electrostatic comb drive that is coupled to an external ring gear through a ratcheting scheme. The actuator can be operated with a single square wave, has minimal rubbing surfaces, maximizes comb finger density, and can be used for open-loop position control. The prototypes function as intended with a minimum demonstrated operating voltage of 18V. The equations of motion are developed for the torsional electrostatic comb drive. The resonant frequency, voltage vs. displacement and force delivery characteristics are predicted and compared with the fabricated device's performance.
Piled Embankment Design Comparison
Drusa, Marián; Kais, Ladislav; Vlček, Jozef; Mečár, Martin
2015-05-01
There are currently several national standards or regulations for the design of the piled embankment, providing suitable solutions for foundation of transport structure on soft, high compressible subsoil, [1]. The most widely used and the best-known standard is British Standard BS8006 [2], which was confronted with another analytical design methodologies (Ebgeo, CUR). Today's popularity and versatility of FEM numerical models brings many advantages, which analytical methods cannot achieved, but must be verified by proposed scaled physical model, which was currently being developed by Department of Geotechnics, University of Žilina.
Pile technology section, annual report for 1955
Energy Technology Data Exchange (ETDEWEB)
1956-03-15
This report is the 1955 annual report from the Pile Technology Section at Hanford. It summarizes work on pile engineering, pile materials, physics research, metallurgy, and fuel technology, related to the production reactors at Hanford.
Numerical Modelling of Large-Diameter Steel Piles at Horns Rev
DEFF Research Database (Denmark)
Augustesen, Anders Hust; Brødbæk, K. T.; Møller, M.
2009-01-01
as foundation for a wind turbine at Horns Rev located in the Danish sector of the North Sea. The outer diameter of the pile is 4 m and the subsoil at the location consists primarily of sand. The behaviour of the pile is investigated under realistic loading conditions by means of a traditional Winkler...
Directory of Open Access Journals (Sweden)
R. Ananda Kumar
2015-01-01
Full Text Available Abstract Retrofitting works are immensely essential for deteriorated and damaged structures in Engineering and Medical fields in order to keep or return to the originality for safe guarding the structures and consumers. In this paper different types of methods of retrofitting review notes are given based on the experimental numerical and analytical methods results on strengthening the Reinforced cement concrete RCC structures including RCC piles. Soil-pile interaction on axial load lateral load reviews are also presented. This review paper is prepared to find out the performance of basalt fibre reinforced polymer BFRP composite retrofitted reinforced cement concrete single end bearing piles.
An Assessment of Cumulative Axial and Torsional Fatigue in a Cobalt-Base Superalloy
Kalluri, Sreeramesh; Bonacuse, Peter J.
2010-01-01
Cumulative fatigue under axial and torsional loading conditions can include both load-order (higMow and low/high) as well as load-type sequence (axial/torsional and torsional/axial) effects. Previously reported experimental studies on a cobalt-base superalloy, Haynes 188 at 538 C, addressed these effects. These studies characterized the cumulative axial and torsional fatigue behavior under high amplitude followed by low amplitude (Kalluri, S. and Bonacuse, P. J., "Cumulative Axial and Torsional Fatigue: An Investigation of Load-Type Sequance Effects," in Multiaxial Fatigue and Deformation: Testing and Prediction, ASTM STP 1387, S. Kalluri, and P. J. Bonacuse, Eds., American Society for Testing and Materials, West Conshohocken, PA, 2000, pp. 281-301) and low amplitude followed by high amplitude (Bonacuse, P. and Kalluri, S. "Sequenced Axial and Torsional Cumulative Fatigue: Low Amplitude Followed by High Amplitude Loading," Biaxial/Multiaxial Fatigue and Fracture, ESIS Publication 31, A. Carpinteri, M. De Freitas, and A. Spagnoli, Eds., Elsevier, New York, 2003, pp. 165-182) conditions. In both studies, experiments with the following four load-type sequences were performed: (a) axial/axial, (b) torsional/torsional, (c) axial/torsional, and (d) torsional/axial. In this paper, the cumulative axial and torsional fatigue data generated in the two previous studies are combined to generate a comprehensive cumulative fatigue database on both the load-order and load-type sequence effects. This comprehensive database is used to examine applicability of the Palmgren-langer-Miner linear damage rule and a nonlinear damage curve approach for Haynes 188 subjected to the load-order and load-type sequencing described above. Summations of life fractions from the experiments are compared to the predictions from both the linear and nonlinear cumulative fatigue damage approaches. The significance of load-order versus load-type sequence effects for axial and torsional loading conditions
Stability in quadratic torsion theories
Energy Technology Data Exchange (ETDEWEB)
Vasilev, Teodor Borislavov; Cembranos, Jose A.R.; Gigante Valcarcel, Jorge; Martin-Moruno, Prado [Universidad Complutense de Madrid, Departamento de Fisica Teorica I, Madrid (Spain)
2017-11-15
We revisit the definition and some of the characteristics of quadratic theories of gravity with torsion. We start from a Lagrangian density quadratic in the curvature and torsion tensors. By assuming that General Relativity should be recovered when the torsion vanishes and investigating the behaviour of the vector and pseudo-vector torsion fields in the weak-gravity regime, we present a set of necessary conditions for the stability of these theories. Moreover, we explicitly obtain the gravitational field equations using the Palatini variational principle with the metricity condition implemented via a Lagrange multiplier. (orig.)
Stability in quadratic torsion theories
Vasilev, Teodor Borislavov; Cembranos, Jose A. R.; Valcarcel, Jorge Gigante; Martín-Moruno, Prado
2017-11-01
We revisit the definition and some of the characteristics of quadratic theories of gravity with torsion. We start from a Lagrangian density quadratic in the curvature and torsion tensors. By assuming that General Relativity should be recovered when the torsion vanishes and investigating the behaviour of the vector and pseudo-vector torsion fields in the weak-gravity regime, we present a set of necessary conditions for the stability of these theories. Moreover, we explicitly obtain the gravitational field equations using the Palatini variational principle with the metricity condition implemented via a Lagrange multiplier.
Aminfar, Ali; Ahmadi, Hamid; Aminfar, Mohammad Hossein
2016-06-01
Offshore jacket-type platforms are attached to the seabed by long batter piles. In this paper, results from a finite element analysis, verified against experimental data, are used to study the effect of the pile's inclination angle, and its interaction with the geometrical properties of the pile and the geotechnical characteristics of the surrounding soil on the behavior of the inclined piles supporting the jacket platforms. Results show that the inclination angle is one of the main parameters affecting the behavior of an offshore pile. We investigated the effect of the inclination angle on the maximum von Mises stress, maximum von Mises elastic strain, maximum displacement vector sum, maximum displacement in the horizontal direction, and maximum displacement in the vertical direction. The pile seems to have an operationally optimal degree of inclination of approximately 5°. By exceeding this value, the instability in the surrounding soil under applied loads grows extensively in all the geotechnical properties considered. Cohesive soils tend to display poorer results compared to grained soils.
Oberlyn Simanjuntak, Johan; Suita, Diana
2017-12-01
Pile foundation is one type deep foundation that serves to distribute the load of hard soil structure loading which has a high bearing capacity that is located deep enough inside the soil. To determine the bearing capacity of the pile and at the same time control the Calendring results, the Pile Driving Analyzer (PDA) test at 8 pile sections from the 84 point piling section (10% of the number sections), the results were analyzed by CAPWAP SOFTWARE, and the highest bearing capacity of Ru 177 ton and the lowest bearing capacity of 111 tons, is bigger than the plan load which load plans that is 60,9 tons. Finally the PDA safe is bearing bearing capacity of the load planning.
Directory of Open Access Journals (Sweden)
V. A. Sernov
2015-01-01
Full Text Available In recent time piled foundations are extensively applied due to an increase of storeys in buildings constructed in Minsk and load increment on the soil. Preference is given to this approach even in the case when relatively firm soil occurs in the top part of the foundation bed. In this case maximum usage of the foundation bed bearing capacity and reduction of foundation cost are considered as top-priority tasks for designers. One of the ways to increase the bearing capacity of piled foundations is the necessity to take into account resistance of foundation bed soil located under raft bottom. The raft as well as a shallow foundation is capable to transfer a significant part of building load into the soil. Such approach makes it possible to reduce a number of piles in the foundation or shorten their length. Then it results in shortening of the construction period and significant reduction in zero cycle. However up to the present moment reliable calculation methods that permit to take into account soil resistance in the raft base. An analysis of previous investigations on the matter executed by various researchers and a number of field investigations have been carried out with the purpose to develop the proposed methods.The paper presents results of field investigations on foundations consisting of short stamped tapered piles which are joined together with the help of the raft fragment. Strength and deformation characteristics of the bases are increasing while making such foundations in the fill-up soil. In this case the filled-up ground layer becomes a bearing layer both for piles and rafts as well. Improvement of high-plastic clay-bearing soil properties is ensured by ramming dry concrete mix under pile foot. The paper describes an experience on application of the piled-raft foundation in complicated engineering and geological conditions while constructing the Orthodox Church in Minsk.
Torsional Rigidity of Minimal Submanifolds
DEFF Research Database (Denmark)
Markvorsen, Steen; Palmer, Vicente
2006-01-01
We prove explicit upper bounds for the torsional rigidity of extrinsic domains of minimal submanifolds $P^m$ in ambient Riemannian manifolds $N^n$ with a pole $p$. The upper bounds are given in terms of the torsional rigidities of corresponding Schwarz symmetrizations of the domains in warped...
Seismic response of pile foundations and pile forces caused by kinematic and inertial interaction
International Nuclear Information System (INIS)
Hartmann, H.G.; Waas, G.
1985-01-01
The horizontal motion and pile forces of pile groups subjected to earthquake excitation are analysed. The piles are modelled as linear elastic beam elements embedded in a layered linear visco-elastic soil medium. Pile-soil-pile interaction is included. The earthquake excitation results from vertically propagating shear waves. Kinematic and inertial interaction effects on foundation motion and pile forces are studied for a single pile, a small pile group and a large pile group. Soft and stiff soil conditions are considered, and the effect of a flexible vs. a rigid halfspace below the soil layers is shown. (orig.)
Evaluation of Limit Loads for Circumferentially Cracked Pipes Under Combined Loadings
Energy Technology Data Exchange (ETDEWEB)
Ryu, Ho-Wan; Han, Jae-Jun; Kim, Yun-Jae [Korea University, Seoul (Korea, Republic of)
2015-05-15
Since the Fukushima nuclear accident, several researchers are extensively studying the effect of torsion on the piping systems In nuclear power plants. Piping installations in power plants with a circumferential crack can be operated under combined loading conditions such as bending and torsion. ASME Code provides flaw evaluations for fully plastic fractures using limit load criteria for the structural integrity of the cracked pipes. According to the recent version of Code, combined loadings are provided only for the membrane and bending. Even though actual operating conditions have torsion loading, the methodology for evaluating torsion load is not established. This paper provides the results of limit load analyses by using finite element models for circumferentially cracked pipes under pure bending, pure torsion, and combined bending and torsion with tension. Theoretical limit load solutions based on net-section fully plastic criteria are suggested and verified with the results of finite element analyses.
Evaluation of Limit Loads for Circumferentially Cracked Pipes Under Combined Loadings
International Nuclear Information System (INIS)
Ryu, Ho-Wan; Han, Jae-Jun; Kim, Yun-Jae
2015-01-01
Since the Fukushima nuclear accident, several researchers are extensively studying the effect of torsion on the piping systems In nuclear power plants. Piping installations in power plants with a circumferential crack can be operated under combined loading conditions such as bending and torsion. ASME Code provides flaw evaluations for fully plastic fractures using limit load criteria for the structural integrity of the cracked pipes. According to the recent version of Code, combined loadings are provided only for the membrane and bending. Even though actual operating conditions have torsion loading, the methodology for evaluating torsion load is not established. This paper provides the results of limit load analyses by using finite element models for circumferentially cracked pipes under pure bending, pure torsion, and combined bending and torsion with tension. Theoretical limit load solutions based on net-section fully plastic criteria are suggested and verified with the results of finite element analyses
Evaluation of bearing capacity of piles from cone penetration test data.
1999-11-01
This study presents an evaluation of the performance of eight cone penetration test (CPT) methods in predicting the ultimate load carrying capacity of square precast prestressed concrete (PPC) piles driven into Louisiana soils. A search in the DOTD f...
Case Study of CPT-based Design Methods for Axial Capacity of Driven Piles in Sand
DEFF Research Database (Denmark)
Thomassen, Kristina; Ibsen, Lars Bo; Andersen, Lars Vabbersgaard
2012-01-01
. Thus, several CPT-based methods have been proposed for the design of offshore driven piles in cohesionless soil such as the UWA-05, ICP-05, and NGI-99 methods. This article treats a case study where the API-method as well as the UWA-05 and NGI-99 methods are compared using CPT-data from an offshore...... loaded offshore driven piles in cohesionless soil has until now been the β-method given in API. The API-method is based on the effective overburden pressure at the depth in question. Previous studies show deviations between full-scale load test measurements of the axial pile capacity and the predictions...
Combined bending-torsion fatigue reliability. III
Kececioglu, D.; Chester, L. B.; Nolf, C. F., Jr.
1975-01-01
Results generated by three, unique fatigue reliability research machines which can apply reversed bending loads combined with steady torque are presented. AISI 4340 steel, grooved specimens with a stress concentration factor of 1.42 and 2.34, and Rockwell C hardness of 35/40 were subjected to various combinations of these loads and cycled to failure. The generated cycles-to-failure and stress-to-failure data are statistically analyzed to develop distributional S-N and Goodman diagrams. Various failure theories are investigated to determine which one represents the data best. The effects of the groove, and of the various combined bending-torsion loads, on the S-N and Goodman diagrams are determined. Two design applications are presented which illustrate the direct useability and value of the distributional failure governing strength and cycles-to-failure data in designing for specified levels of reliability and in predicting the reliability of given designs.
International Nuclear Information System (INIS)
Ugachi, Hirokazu; Tsukada, Takashi; Kaji, Yoshiyuki; Nagata, Nobuaki; Dozaki, Koji; Takiguchi, Hideki
2003-01-01
Irradiation assisted stress corrosion cracking (IASCC) is caused by the synergistic effects of neutron irradiation, stress and corrosion by high temperature water. It is, therefore, essential to perform in-pile SCC tests, which are material tests under the conditions simulating those of actual LWR operation, in order to clarify the precise mechanism of the phenomenon, though mainly out-of-pile SCC tests for irradiated materials have been carried out in this research field. There are, however, many difficulties to perform in-pile SCC tests. Performing in-pile SCC tests, essential key techniques must be developed. Hence as a part of development of the key techniques for in-pile SCC tests, we have embarked on development of the test technique which enables us to obtain the information concerning the effect of such parameters as applied stress level, water chemistry, irradiation conditions, etc. on the crack initiation behavior. Although it is difficult to detect the crack initiation in in-pile SCC tests, the crack initiation can be evaluated by the detection of specimen rupture if the cross section area of the specimen is small enough. Therefore, we adopted the uniaxial constant loading (UCL) test with small tensile specimens. This paper will describe the current status of the development of several techniques for in-pile SCC initiation tests in JMTR and the results of the performance tests of the designed testing unit using the out-of-pile loop facility. (author)
Ocular torsion before and after 1 hour centrifugation
Groen, E.; Graaf, B. de; Bles, W.; Bos, J.E.
1996-01-01
To assess a possible otolith contribution to effects observed following prolonged expo-sure to hyper gravity, we used video-oculography to measure ocular torsion during static and dynamic conditions of lateral body tilt (roll) before and after one hour of centrifugation with a Gx-load of 3G. Static
Ocular torsion before and after 1 hour centrifugation
Groen, Eric; De Graaf, Bernd; Bles, Willem; Bos, Jelte E.
1996-01-01
To assess a possible otolith contribution to effects observed following prolonged exposure to hypergravity, we used video oculography to measure ocular torsion during static and dynamic conditions of lateral body tilt (roll) before and after t h of centrifugation with a G(x)-load of 3 G. Static tilt
Underwater noise reduction of marine pile driving using a double pile.
2015-12-01
Impact pile driving of steel piles in marine environments produces extremely high sound levels in the water. : It has been shown that current pile driving noise attenuation techniques, such as bubble curtains and : cofferdams, provide limited noise r...
Ovarian torsion: Echographic discoveries
International Nuclear Information System (INIS)
Triana R, Gustavo; Navas O, Claudia
1994-01-01
Patient of 31 years who consulted to the even service of urgencies to present of two hours of evolution intense pain in flank and region lumbar left, associated to vomit, present square similar 5 previous days to the entrance in the right side. Go Po, plans with DIU FUR, 8 previous days to the square. It is practiced Tran abdominal pelvic echography that shows left ovary of 6 x 5 x 3 cms, with multiple follicular images, of thick walls, with I liquidate free abdominal, highly suggestive of ovarian torsion although the patient didn't present square of sharp abdomen. It decides to suspend analgesic and to value it, presented sharp abdominal pain, reason why laparotomy was practiced, finding mass of 6 x 6 cms. of necrotic aspect, corresponding to the left ovary, which presented three turns on their axis. It is taken finish left salpingooferectomy
ESTIMATION OF AGING EFFECTS OF PILES IN MALAYSIAN OFFSHORE LOCATIONS
Directory of Open Access Journals (Sweden)
JERIN M. GEORGE
2017-04-01
Full Text Available An increasing demand for extending life and subsequently higher loading requirements of offshore jacket platforms are among the key problems faced by the offshore industry. The Aging effect has been proved to increase the axial capacity of piles, but proper methods to estimate and quantify these effects have not been developed. Borehole data from ten different Malaysian offshore locations have been analysed and they were employed to estimate the setup factor for different locations using AAU method. The setup factors found were used in the Skov and Denver equation to calculate capacity ratios of the offshore piles. The study showed that there will be an average improvement in the axial capacity of offshore piles by 42.2% and 34.9% for clayey and mixed soils respectively after a time equal to the normal design life (25 years of a jacket platform.
DEFF Research Database (Denmark)
Hyttel, Trine E W; Bak, Geske S; Larsen, Solveig B
2015-01-01
The increasing use of de-torsion of the ovaries may result in re-torsion. This review addresses risk of re-torsion and describes preventive strategies to avoid re-torsion in pre-menarcheal girls, and fertile and pregnant women. We clinically reviewed PubMed, Embase, Trip and Cochrane databases...
Simplified calculation methods for all-vertical-piled wharf in offshore deep water
Wang, Yuan-zhan; He, Lin-lin
2017-04-01
All-vertical-piled wharf is a kind of high-piled wharf, but it is extremely different from the traditional ones in some aspects, such as the structural property, bearing characteristics, failure mechanism, and static or dynamic calculation methods. In this paper, the finite element method (FEM) and theoretical analysis method are combined to analyze the structural property, bearing behavior and failure mode of the all-vertical-piled wharf in offshore deep water, and to establish simplified calculation methods determining the horizontal static ultimate bearing capacity and the dynamic response for the all-vertical-piled wharf. Firstly, the bearing capability and failure mechanism for all-vertical-piled wharf are studied by use of FEM, and the failure criterion is put forward for all-vertical-piled wharf based on the `plastic hinge'. According to the failure criterion and P-Y curve method, the simplified calculation method of the horizontal static ultimate bearing capacity for all-vertical-piled wharf is proposed, and it is verified that the simplified method is reasonable by comparison with the FEM. Secondly, the displacement dynamic magnification factor for the all-vertical-piled wharf under wave cyclic loads and ship impact loads is calculated by the FEM and the theory formula based on the single degree of freedom (SDOF) system. The results obtained by the two methods are in good agreement with each other, and the simplified calculation method of the displacement dynamic magnification factor for all-vertical-piled wharf under dynamic loads is proposed. Then the simplified calculation method determining the dynamic response for the all-vertical-piled wharf is proposed in combination with P-Y curve method. That is, the dynamic response of the structure can be obtained through the static calculation results of P-Y curve method multiplied by the displacement dynamic magnification factor. The feasibility of the simplified dynamic response method is verified by
Spin and torsion in gravitation
De Sabbata, Venzo
1994-01-01
This book gives an exposition of both the old and new results of spin and torsion effects on gravitational interactions with implications for particle physics, cosmology etc. Physical aspects are stressed and measurable effects in relation to other areas of physics are discussed.Among the topics discussed are: alternative ways of unifying gravity with electroweak and strong interactions by an energy dependent spin torsion coupling constant; the idea that all interactions can be understood as originating from spin curvature coupling; the possibility of cosmological models with torsion providing
DEFF Research Database (Denmark)
Hansen, Klavs Feilberg; Pedersen, Carsten Mørk
2008-01-01
be carried out directly in a normal testing machine. The torsion strength is believed to be the most important parameter in out-of-plane resistance of masonry walls subjected to bending about an axis perpendicular to the bed joints. The paper also contains a few test results from bending of small walls about...... an axis perpendicular to the bed joints, which indicate the close connection between these results and results from torsion tests. These characteristics make the torsion strength well suited to act as substitute parameter for the bending strength of masonry about an axis perpendicular to the bed joints....
Surface crack growth in cylindrical hollow specimen subject to tension and torsion
Shlyannikov, V.; Yarullin, R.; Ishtyryakov, I.
2015-01-01
The subject for studies is an aluminium cylindrical hollow specimen with external axial and part circumferential semi-elliptical surface crack undergoing fatigue loads. Both the optical microscope measurements and the crack opening displacement (COD) method are used to monitor and calculate both crack depth and crack length during the tests. The variation of crack growth behaviour is studied under cyclic axial tension, pure torsion and combined tension+torsion fatigue loading. For...
Multi-scale sensitivity analysis of pile installation using DEM
Esposito, Ricardo Gurevitz; Velloso, Raquel Quadros; , Eurípedes do Amaral Vargas, Jr.; Danziger, Bernadete Ragoni
2017-12-01
The disturbances experienced by the soil due to the pile installation and dynamic soil-structure interaction still present major challenges to foundation engineers. These phenomena exhibit complex behaviors, difficult to measure in physical tests and to reproduce in numerical models. Due to the simplified approach used by the discrete element method (DEM) to simulate large deformations and nonlinear stress-dilatancy behavior of granular soils, the DEM consists of an excellent tool to investigate these processes. This study presents a sensitivity analysis of the effects of introducing a single pile using the PFC2D software developed by Itasca Co. The different scales investigated in these simulations include point and shaft resistance, alterations in porosity and stress fields and particles displacement. Several simulations were conducted in order to investigate the effects of different numerical approaches showing indications that the method of installation and particle rotation could influence greatly in the conditions around the numerical pile. Minor effects were also noted due to change in penetration velocity and pile-soil friction. The difference in behavior of a moving and a stationary pile shows good qualitative agreement with previous experimental results indicating the necessity of realizing a force equilibrium process prior to any load-test to be simulated.
Bore pile foundation tall buildings closed in the heritage building
Triastuti, Nusa Setiani
2017-11-01
Bore pile foundation for high building surroundings heritage building should be not damage. Construction proses must good, no necking, no mixed deep water, no sliding soil, nonporous concrete. Objective the execution of bore pile so that heritage buildings and neighboring buildings that are old do not experience cracks, damage and tilting. The survey methodology was observe the process of the implementation of the dominant silt, clay soil, in addition a limited space and to analyze the results of loading tests, investigations of soil and daily reports. Construction process determines the success of the structure bore pile in high building structure bearing, without damaging a heritage building. Attainment the hard soil depth, density concrete, observable clean reinforcement in the implementation. Monitoring the implementation of, among others, the face of the ground water little reduce in the area and outside the footprint of the building, no impact of vibration drilling equipment, watching the mud content on the water coming out at the time of drilling, concrete volume was monitored each 2 m bore depth of pile, The result researched heritage building was not damage. The test results bore pile axial, lateral analyzed the results have the appropriate force design required.
Directory of Open Access Journals (Sweden)
Mojtaba Shokri
2017-02-01
Full Text Available One of the most important strengths of concrete structures is their torsional strength in different loads. This strengthening could have a significant impact on increasing tolerability of structure relative to lateral and vertical loads and vibrations. In order to withstand the additional loads, reinforced polymers (FRP are used today. The present study investigated the effect of using polymer composite sheets CFRP on the torsional strength and ultimate deformation of beam. Research method is practical and in this study, four types of beams with different dimensions are used to examine the effect of different loads on the torsional strength.
Bezci, Semih E; Klineberg, Eric O; O'Connell, Grace D
2018-01-01
The intervertebral disc is a complex joint that acts to support and transfer large multidirectional loads, including combinations of compression, tension, bending, and torsion. Direct comparison of disc torsion mechanics across studies has been difficult, due to differences in loading protocols. In particular, the lack of information on the combined effect of multiple parameters, including axial compressive preload and rotation angle, makes it difficult to discern whether disc torsion mechanics are sensitive to the variables used in the test protocol. Thus, the objective of this study was to evaluate compression-torsion mechanical behavior of healthy discs under a wide range of rotation angles. Bovine caudal discs were tested under a range of compressive preloads (150, 300, 600, and 900N) and rotation angles (± 1, 2, 3, 4, or 5°) applied at a rate of 0.5°/s. Torque-rotation data were used to characterize shape changes in the hysteresis loop and to calculate disc torsion mechanics. Torsional mechanical properties were described using multivariate regression models. The rate of change in torsional mechanical properties with compression depended on the maximum rotation angle applied, indicating a strong interaction between compressive stress and maximum rotation angle. The regression models reported here can be used to predict disc torsion mechanics under axial compression for a given disc geometry, compressive preload, and rotation angle. Copyright © 2017 Elsevier Ltd. All rights reserved.
Stress Analysis of CFG Pile Composite Foundation in Consolidating Saturated Mine Tailings Dam
Directory of Open Access Journals (Sweden)
Jinxing Lai
2016-01-01
Full Text Available Cement fly-ash gravel (CFG pile is a widely used ground reinforcement technique. This paper aims to address the mechanical characteristics of CFG composite foundation in consolidating saturated mine tailings (MTs dam. The field static load tests were employed to explore the bearing capacity of the CFG composite foundation, and finite element (FE models in three dimensions validated through comparison with experimental results were used to discuss the pile-soil stress distribution and pile-soil stress ratio of the CFG composite foundation. The results indicate that the distribution of earth pressure and pile stress is relatively homogeneous and stable over depth and load, while the development of CFG composite foundation bearing capacity is insufficient, in which the developed bearing capacity of CFG piles is less than 50% of its characteristic value. Additionally, compared with the laboratory model test results, the pile-soil stress ratio decreases with the increasing of the load in FEM results proved to better conform to the actual engineering conditions. Furthermore, the deformation modulus and thickness of cushion exert significant influence on pile-soil stress ratio and integral bearing capacity of CFG composite foundation.
International Nuclear Information System (INIS)
Maheshwari, B.K.; Truman, K.Z.; El Naggar, M.H.; Gould, P.L.
2004-01-01
The effects of material nonlinearity of soil and separation at the soil-pile interface on the dynamic behaviour of a single pile and pile groups are investigated. An advanced plasticity-based soil model, hierarchical single surface (HiSS), is incorporated in the finite element formulation. To simulate radiation effects, proper boundary conditions are used. The model and algorithm are verified with analytical results that are available for elastic and elastoplastic soil models. Analyses are performed for seismic excitation and for the load applied on the pile cap. For seismic analysis, both harmonic and transient excitations are considered. For loading on the pile cap, dynamic stiffness of the soil-pile system is derived and the effect of nonlinearity is investigated. The effects of spacing between piles are investigated, and it was found that the effect of soil nonlinearity on the seismic response is very much dependent on the frequency of excitation. For the loading on a pile cap, the nonlinearity increases the response for most of the frequencies of excitation while decreasing the dynamic stiffness of the soil-pile system. (author)
Collapse mechanisms and strength prediction of reinforced concrete pile caps
DEFF Research Database (Denmark)
Jensen, Uffe G.; Hoang, Linh Cao
2012-01-01
This paper describes an upper bound plasticity approach for strength prediction of reinforced concrete pile caps. A number of collapse mechanisms are identified and analysed. The procedure leads to an estimate of the load-carrying capacity and an identification of the critical collapse mechanism....... Calculations have been compared with nearly 200 test results found in the literature. Satisfactory agreement has been found. The analyses are conducted on concentrically loaded caps supported by four piles. The paper briefly outlines how the approach may be extended to more complicated loadings and geometries....... It is argued that the upper bound approach may be a useful complement to the widely used lower bound strut-and-tie method. Especially when dealing with strength assessment of existing structures....
Undrained behavior of auger cast-in-place piles in multilayered soil
Directory of Open Access Journals (Sweden)
Fathi M. Abdrabbo
2013-06-01
Full Text Available Auger cast-in-place piles (ACIP are often installed through multilayered soil profiles, which make accurate predictions of the performance of the piles more complex than piles constructed in either clay or sand deposits. This study is intended to shed some light on the undrained behavior of ACIP embedded in stratified soil and to explore a methodology to predict the ultimate pile loads. The study is based on practical measurements of load–displacement relationships of 51 static loading tests of full-scale ACIP installed through multilayered soil profiles. The study revealed that the normalized load–displacement relationships of the tested piles have deterministic range with upper and lower bounds. Equations for these bounds and the mean load–displacement relationship are developed in this study. There is a deficiency in the literature concerning the calculations of ultimate loads for piles embedded in multilayered soil. Therefore, this paper presents an attempt to estimate the ultimate pile load in undrained conditions utilizing two approaches. The first approach assumed the failure pattern of the soil beneath the pile base to be punching into the sand followed by general shear failure in clay underneath. The end-bearing resistance at the pile tip was estimated by implementing Meyerhof and Hanna’s [24] shallow foundation procedure. The second approach assessed the depth of the influence zone below the pile tip using isobars of pressure around and below the pile tip due to a point load, based on the theory of elasticity and characterization of a semi-infinite soil mass (Martins [3]. Soil layers, within the zone of influence, were considered to be an equivalent geomaterial with shear strength parameters computed by weighted average of shear strength parameters of the soil sub-layers. For comparison purposes, the ultimate pile load of each test was interpreted experimentally using the method proposed by Chin (1970. Reasonable agreement was
Constraining spacetime torsion with LAGEOS
March, Riccardo; Bellettini, Giovanni; Tauraso, Roberto; Dell'Agnello, Simone
2011-11-01
We compute the corrections to the orbital Lense-Thirring effect (or frame-dragging) in the presence of spacetime torsion. We analyze the motion of a test body in the gravitational field of a rotating axisymmetric massive body, using the parametrized framework of Mao, Tegmark, Guth and Cabi. In the cases of autoparallel and extremal trajectories, we derive the specific approximate expression of the corresponding system of ordinary differential equations, which are then solved with methods of Celestial Mechanics. We calculate the secular variations of the longitudes of the node and of the pericenter. We also show how the LAser GEOdynamics Satellites (LAGEOS) can be used to constrain torsion parameters. We report the experimental constraints obtained using both the nodes and perigee measurements of the orbital Lense-Thirring effect. This makes LAGEOS and Gravity Probe B complementary frame-dragging and torsion experiments, since they constrain three different combinations of torsion parameters.
Development of Torsional and Linear Piezoelectrically Driven Motors
Duong, Khanh; Newton, David; Garcia, Ephrahim
1996-01-01
The development of rotary and linear inchworm-motors using piezoelectric actuators is presented. The motors' design has the advantage of a macro and micro stepper motor with high load and speed. The torsional design is capable of fast angular positioning with micro level accuracy. Additionally, the rotary motor, as designed, can be used as a clutch/brake mechanism. Constructed prototype motors of both types along with their characteristics are presented. The torsional motor consists of a torsional section that provides angular displacement and torque, and two alternating clamping sections which provide the holding force. The motor relies on the principal piezoelectric coupling coefficient (d33) with no torsional elements, increasing its torque capability. The linear motor consists of a longitudinal vibrator that provides displacement and load, and two alternating clamping sections which provide the holding force. This design eliminates bending moment, tension and shear applied to the actuator elements, increase its load capability and life. Innovative flexure designs have been introduced for both motor types. Critical issues that affect the design and performance of the motors are explored and discussed. Experiments are performed demonstrating the motor prototypes based on the aforementioned design considerations.
DEFF Research Database (Denmark)
Pagola, Maria Alberdi; Madsen, Søren; Jensen, Rasmus Lund
2017-01-01
Pile heat exchangers are traditional foundation piles with built in heat exchangers. As such, the footing of the building both serves as a structural component and a heating/cooling supply element. The existing geotechnical design standards do not consider the nature of thermo-active foundations...... and, therefore, there is a need to develop guidelines to design them properly. This paper contributes by studying the thermo-mechanical behavior of the precast piles which are 15-meter long and have a quadratic cross section and a W-shape pipe heat exchanger. This article aims to numerically assess...... the additional changes in the pile load transfer generated by its heating and cooling. In addressing this objective, a preliminary multi-physical finite element analysis is conducted which serves as a tool for exploring: i) the thermally induced mechanical stresses within the concrete and on the pile-soil axial...
Settlement Analysis of Saturated Tailings Dam Treated by CFG Pile Composite Foundation
Directory of Open Access Journals (Sweden)
Jinxing Lai
2016-01-01
Full Text Available Cement fly ash gravel (CFG pile composite foundation is an effective and economic foundation treatment approach, which is significant to building foundation, subgrade construction, and so forth. The present paper aims at investigating the settlement behaviors of saturated tailings dam soft ground under CFG pile composite foundation treatment, in which FEM and laboratory model test were utilized. The proposed findings demonstrate that CFG pile treatment is effective in reinforcing saturated tailings dam and loading has little influence on settlement of soil between piles. The variation of soil between piles settlement in FEM has a good agreement with the laboratory model test. Additionally, the cushion deformation modulus has a small effect on the composite foundation settlement, although the cushion thickness will generate certain influence on the settlement distribution of the composite foundation.
Study on Dynamic Characteristics of Heavy Machine Tool-Composite Pile Foundation-Soil
Directory of Open Access Journals (Sweden)
CAI Li-Gang
2014-09-01
Full Text Available Heavy duty computer numerical control machine tools have characteristics of large self-weight, load and. The insufficiency of foundation bearing capacity leads to deformation of lathe bed, which effects machining accuracy. A combined-layer foundation model is created to describe the pile group foundation of multi-soil layer in this paper. Considering piles and soil in pile group as transversely isotropic material, equivalent constitutive relationship of composite foundation is constructed. A mathematical model is established by the introduction of boundary conditions, which is based on heavy duty computer numerical control machine tools-composite pile foundation-soil interaction system. And then, the response of different soil and pile depth is studied by a case. The model improves motion accuracy of machine tools.
Probabilistic pseudostatic analysis of pile in laterally spreading ground: Two layer soil profile
Directory of Open Access Journals (Sweden)
Reda Farag
2014-06-01
Full Text Available Coupling the finite element model of pile under lateral spread with the Monte Carlo Simulation is frequently prohibited by excessive lengthily computations. In the present paper, a simplified pseudostatic method is integrated with an improved response surface scheme to evaluate the reliability of pile subjected to lateral spread. The pseudostatic model takes both geometric and soil nonlinearities into account, while, the response surface formulation takes; load, geometry, material and model uncertainties into consideration. First; the improved response surface scheme is suggested and validated with the help of a simple example. Then, the pseudostatic model of a full size pile under lateral spread is integrated with the improved response surface scheme in order to assess the pile reliability. In the considered example, for both operational and structural possible modes of failure, it has been found that the most influential random variables are lateral displacement, and pile radius, respectively.
Energy piles. A fundamental energy pile; Energiepfaehle. Eine fundamentale Energiequelle
Energy Technology Data Exchange (ETDEWEB)
Kaiser, Holger; Beldermann, Nico [GF-Tec GmbH, Roedermark (Germany)
2013-03-01
The Maintower, the new airport in Berlin/Brandenburg, a lot of Ikea buildings, and also small office buildings or residential buildings may exchange energy with the underground by means of pile fundaments. At the correct planning and execution, energy piles are low-cost geothermal power plants which sustainable generate heating and cooling for the buildings standing on them. Even more energy can be generated safely under compliance with the groundwater protection by means of a new development of the material and the transfer.
Directory of Open Access Journals (Sweden)
R. Barros
Full Text Available On Precast concrete structures the column foundation connections can occur through the socket foundation, which can be embedded, partially embedded or external, with socket walls over the pile caps. This paper presents an experimental study about two pile caps reinforced concrete with external, partially embedded and embedded socket submitted to central load, using 1:2 scaled models. In the analyzed models, the smooth interface between the socket walls and column was considered. The results are compared to a reference model that presents monolithic connections between the column and pile cap. It is observed that the ultimate load of pile cap with external sockets has the same magnitude as the reference pile cap, but the ultimate load of models with partially embedded and embedded socket present less magnitude than the reference model.
Effect of torsion moment on failure bending moment for circumferentially cracked pipe
International Nuclear Information System (INIS)
Li, Yinsheng; Hasegawa, Kunio; Ida, Wataru; Hoang, Phuong H.; Bezensek, Bostjan
2010-01-01
When a crack is detected in a stainless steel pipe during in-service inspection, the limit load criterion given in the codes such as JSME Rules on Fitness-for-Service for Nuclear Power Plants or ASME Boiler and Pressure Vessel Code Section XI can be applied to evaluate the integrity of the pipe. However, in the current codes, the limit load criterion is only provided considering pressure and bending moment. The torsion moment is not considered, although torsion moment does exist in the nuclear power piping system. In this paper, finite element analyses are carried out for stainless steel pipe containing a circumferential surface crack under the combination of bending moment and torsion moment, considering different pipe dimensions and flaw sizes. Based upon the analysis results, a plastic collapse estimation method is proposed considering the existence of the torsion moment and its magnitude, and this method make it possible to evaluate the integrity of the pipe for general loading conditions. (author)
Directory of Open Access Journals (Sweden)
Chayanon Hansapinyo
2003-01-01
Full Text Available This paper presents the experimental investigation on the failure mechanism and ultimate capacity of rectangular reinforced concrete beam under combined action of bi-axial shear accompanied with torsion through the test of four reinforced concrete members. The simple experimental set-up for a simply-supported beam under one point loading is introduced in this study by applying eccentric load to the tilted beam. This requires only one hydraulic jack to produce the complicated bi-axial shear and torsional loading. The main parameter is the magnitude of torsion induced to specimens which is relatively represented by the torsion-to-shear ratio. In addition, the influence of torsion on ultimate capacity of reinforced concrete with different ratio of two shears is investigated. From the experimental results, it is found that the increase in the magnitude of torsion about 69 percent drastically decreases bi-axial shear capacity as much as 12 to 39 percent according to the ratio of bi-axial shears. The experimental results are compared with the capacities calculated by the available interaction formula between uni-axial shear and torsion in the current design codes. The comparison indicates that the current design codes give quite conservative values of ultimate capacity.
Torsional Stiffness Comparison of Different Tube Cross-Sections of a Formula SAE Car Space Frame
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Hao Liu Cong
2018-01-01
Full Text Available Since torsional loading and the accompanying deformation of the frame and suspension parts can affect the handling and performance of the car, torsional stiffness is generally thought to be a primary determinant of frame performance for a FSAE car. According to the FSAE Rules, different tube cross-sections are available for some members of a space frame. By finite element simulation, this research compared different tube shapes and thicknesses. Compared with 1.6 mm thickness round tube, square tube with the same wall thickness can improve the torsional stiffness by 23% in test Mode I, and 65% in test Mode II. The 1.2mm thickness square tube also can improve the torsional stiffness by 6% and 39% in test Mode I and Mode II. From these comparisons, it can be found the usage of square tube can improve the frame torsional stiffness efficiently.
Dynamic Bending and Torsion Stiffness Derivation from Modal Curvatures and Torsion Rates
MAECK, J.; DE ROECK, G.
1999-08-01
In order to maintain the reliability of civil engineering structures, considerable effort is currently spent on developing a non-destructive vibration testing method for monitoring the structural integrity of constructions. The technique must be able to observe damage, secondly to localize the damage; and finally to give an idea of the severity of the damage. Within the framework of relating changes of measured modal parameters to changes in the integrity of the structure, it is important to be able to determine the dynamic stiffness in each section of the structure from measured modal characteristics.A damaged structure results in a dynamic stiffness reduction of the cracked sections. The dynamic stiffnesses provide directly an indication of the extension of the cracked zones in the structure. The dynamic stiffness reduction can also be associated with a degree of cracking in a particular zone.In an experimental programme, a concrete beam of 6 m length is subjected to an increasing static load to produce cracks. After each static perload, the beam is tested dynamically in a free-free set-up. The change in modal parameters is then related to damage in the beam.The technique that will be presented in the paper to predict the damage location and intensity is a direct stiffness derivation from measured modal displacement derivatives. Using the bending modes, the dynamic bending stiffness can be derived from modal curvatures. Using the torsional modes, the dynamic torsion stiffness can be derived from modal torsion rates.
Huang, Xianbin; Liu, Chenyang; Chen, Chunyang; Wangren, Yahong; Xu, Jialin; Xian, Jin
2018-03-01
The group of pile foundation of no.5 pier in Shoujiang Bridge needs to overcome the big load of large span continuous steel structure. The length of single pile foundation is 77m and the diameter of single pile foundation is 250cm. It not only faces the flood in the upstream of Shoujiang river, the construction obstacles during summer rain period, but also the reservoir clearance activity of Zipingpu reservoir and the high water level in winter and other water level fluctuation that have huge impact on platform of pile foundation construction. This article introduces the preparation in aspect of personnel, material, equipment and so on of pile foundation construction, and also conduct intensive research on leveling the field, assaying pile location, the embedment of the steel casing, installing the drill, mixing mud, drilling, final hole inspection and clearance, steel cage construction, perfusing concrete under water.
Torsional superelasticity of NiTi archwires.
Bolender, Yves; Vernière, Anne; Rapin, Christophe; Filleul, Marie-Pierryle
2010-11-01
To reproduce and compare the intraoral torsional behavior of 10 commonly used preformed upper NiTi 0.017 x 0.025 archwires in 0.018-slot brackets at 20 degrees C, 35 degrees C, and 55 degrees C. Ten upper preformed NiTi archwires were compared to a multibraided stainless steel wire. An original testing bench was used to reproduce palatal root torque applied onto an upper central incisor with a maximum value of 1540 g x mm. Ten samples of each wire type were tested at 20 degrees C, 35 degrees C, and 55 degrees C each. Loading and unloading at 20 degrees C revealed three categories of wires: a group of four NiTi wires of relative stiffness bereft of any superelasticity, a group of six NiTi wires displaying some horizontal plateau, and finally the stainless steel wire of lesser stiffness. Testing at the average oral temperature of 35 degrees C produced the same three categories of wires, with only 2 of 10 NiTi wires displaying a superelastic effect (Copper NiTi 35 degrees C and 40 degrees C). None of the NiTi wires was superelastic at 55 degrees C. Moments increased with temperature as the martensite was replaced by the more rigid austenite. This study showed that most NiTi wires did not exhibit in torsion the superelastic effect traditionally described in bending. The combination of straight-wire prescriptions and rectangular superelastic NiTi archwires did not provide optimal constant moments necessary to gain third-order control of tooth movement early in treatment. A braided stainless steel rectangular archwire displayed better torsional behavior at 35 degrees C than most NiTi archwires of the same dimensions.
Vertical Equilibrium of Sheet Pile Walls with Emphasis on Toe Capacity and Plugging
DEFF Research Database (Denmark)
Iversen, Kirsten Malte; Augustesen, Anders Hust; Nielsen, Benjaminn Nordahl
Constructions including retaining walls are normally established in areas where it is impossible to conduct an excavation with inclined sides. Due to large excavation depths and due to restrictions on the deformations of the wall, it is often necessary to anchor the wall. The limited space makes...... at the pile toe to fulfil vertical equilibrium. The paper describes a case study of sheet pile walls in Aalborg Clay, and the amount of loads transferred as point loads at the pile toe for free and anchored walls is estimated. A parametric study is made for the free wall with regards to the height...... and the roughness of the wall. Due to limitations of the calculation method, the study of the anchored wall only includes variation of the roughness. For the case study, it is found that the vertical equilibrium is fulfilled for the considered free wall. An anchored wall needs a plug forming at the pile toe...
Torsional Phacoemulsification and Tip Selection
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Fırat Helvacıoğlu
2014-10-01
Full Text Available One of the recent advances in cataract surgery is torsional phacoemulsification. It was developed to increase the efficacy of ultrasonic emulsification. In torsional phacoemulsification, the torsional movement of the tip is translated to side-to-side cutting action with the aid of bent phaco tips. Lens material is cut in both directions, rather than only during a forward stroke. The efficiency of this technique is further enhanced by an improvement in followability provided by the inherent non-repulsive nature of the side-to-side motion. Tip selection is very important for the efficiency of torsional phacoemulsification. Theoretically, there are 2 ways to enhance the cutting efficiency of the tip. First is the stroke length; the 22-degree bent 30-degree Kelman mini-flared tip cuts longer than the 12-degree bent 30-degree mini-flared Kelman tip. Second is the angulation or bevel; the higher the degree (45 degrees, the better cutting efficiency. Retrospective analyses of the previously published clinical studies clearly demonstrated that the efficacy of the torsional phacoemulsification has positive correlation with both the aperture angles and neck angles of the tips. (Turk J Ophthalmol 2014; 44: 392-5
International Nuclear Information System (INIS)
Mazancourt, R. de
1957-10-01
After a presentation of the experimental conditions (pile status and condition, atmospheric conditions and detector locations, establishment of flux maps), the authors reports the performed data analysis: general principles, least square method, graphical determination. Results are discussed in the case of gold (analysis of rough counts, analysis after extraction of the second harmonic) and indium (rough counts, cadmium rate)
DRIVEN POLYSTRONG REINFORCED CONCRETE PILES AND NEW DESIGN OF PILE CAPS
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I. I. Bekbasarov
2015-01-01
Full Text Available The paper presents constructional and technological features for manufacturing driven piles with variable strength of pile shaft. Economical efficiency of their production has been shown in the paper. The paper provides a pile cap design that ensures perception of hammer impacts with the help of lateral edges of the pile cap. Driven reinforced concrete piles which are manufactured from three shaft sections having various strength have been proposed in the paper. Material strength (concrete grade and diameter of bars and length of shaft sections are given on a case by case basis in accordance with nature and rate of stresses in piles during their driving process. Manufacturing of polystrong piles provides an opportunity to select them for a particular construction site with due account of their preservation during driving process.A pile cap has been developed that as opposed to existing analogous designs makes it possible to transmit impact efforts from a hammer to the pile through lateral surface of its head part. The pile cap provides the possibility to increase an area for perception of hammer impact efforts by the pile and in doing so it is possible significantly to reduce a damage risk and destruction of pile concrete during its driving. Application of polystrong piles and their driving with the help of new pile cap are considered as a basis for defect-free and resource-saving technology for pile foundations in the construction.
The Method of Calculating the Settlement of Weak Ground Strengthened with the Reinforced Sandy Piles
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Maltseva Tatyana
2016-01-01
Full Text Available The paper presents an engineering method for calculating the weak clay base, strengthened with sandy piles reinforced along the contour. The method is based on the principle of layer-by-layer summation, which is used when designing the bases and foundations. The novelty of the suggested method lies in the taking account of the soil reaction along the pile lateral surface and the impact of external vertical loads on the vertical displacement of the base.
Numerical Simulation by using Soldiers Pile of the Embankment on Semarang-Solo Highway
Tumanduk, M. S. S. S.; Maki, T. S.; Pangkey, T. U. Y.; Pandeiroth, Y. C.
2018-02-01
Semarang-Solo highway works section II Gedawang-Penggaron constitutes a labile area. It is thought to be effect of the existence of coat clay shale which have moulded. For the purpose of anticipating the embankment mass movement it is placed line bored pile and stringed up (soldiers pile). The objective of this research is to know the efficient use of soldier’s pile of the embankment on Semarang-Solo highway section II Gedawang-Penggaron pursuant based upon numerical simulation. The result of analysis depicts that original slope in a stabil state with horizontal displacement which equal to 0.06 m and safety factor (SF) which equal to 1.31. The strengthened embankment with bored pile is not effective to give am SF improvement at slope so that, at this phase, the slope cannot be slid to be safe enough from landslide namely with horizontal displacement which equal to 0.20 m and SF which equal to 1.09. The effect of traffic load horizontal displacement is which equal to 0.21 m with SF which equal to 1.00. The earthquake simulation results horizontal displacement which equal to 0.75 m with SF which equal to 1.00. Long variation of bored pile of phase II by neglecting bored pile phase III at the depth 35 m yields horizontal displacement which equal to 0.03 m and SF optimum which equal to 2.17. The variation of pile location by placing bored pile under embankment slope foot with distance from the location of bored pile of phase II which equal to 20 m without changing the profile of the existing bored pile creates the horizontal displacement which equals to 0.02 m with SF which equal to 2.29. The result of the horizontal displacement and SF of the two alternative is safer compared to the existing condition (SF>1.5).
Directory of Open Access Journals (Sweden)
Konkol Jakub
2017-03-01
Full Text Available In this paper, the whole process of pile construction and performance during loading is modelled via large deformation finite element methods such as Coupled Eulerian Lagrangian (CEL and Updated Lagrangian (UL. Numerical study consists of installation process, consolidation phase and following pile static load test (SLT. The Poznań site is chosen as the reference location for the numerical analysis, where series of pile SLTs have been performed in highly overconsolidated clay (OCR ≈ 12. The results of numerical analysis are compared with corresponding field tests and with so-called “wish-in-place” numerical model of pile, where no installation effects are taken into account. The advantages of using large deformation numerical analysis are presented and its application to the pile designing is shown.
Aerial sampling of emissions from biomass pile burns in ...
Emissions from burning piles of post-harvest timber slash in Grande Ronde, Oregon were sampled using an instrument platform lofted into the plume using a tether-controlled aerostat or balloon. Emissions of carbon monoxide, carbon dioxide, methane, particulate matter (PM2.5 µm), black carbon, ultraviolet absorbing PM, elemental/organic carbon, semi-volatile organics (polycyclic aromatic hydrocarbons and polychlorinated dibenzodioxins/dibenzofurans), filter-based metals, and volatile organics were sampled for determination of emission factors. The effect on emissions from covering or not covering piles with polyethylene sheets to prevent fuel wetting was determined. Results showed that the uncovered (“wet”) piles burned with lower combustion efficiency and higher emissions of volatile organic compounds. Results for other pollutants will also be discussed. This work determined the emissions from open burning of forest slash wood, with and without plastic sheeting. The foresters advocate the use of plastic to keep the slash wood dry and aid in the controlled combustion of the slash to reduce fuel loading. Concerns about the emissions from the burning plastic prompted this work which conducted an extensive characterization of dry, wet, and dry with plastic slash pile emissions.
Dirac operators and Killing spinors with torsion
International Nuclear Information System (INIS)
Becker-Bender, Julia
2012-01-01
On a Riemannian spin manifold with parallel skew torsion, we use the twistor operator to obtain an eigenvalue estimate for the Dirac operator with torsion. We consider the equality case in dimensions four and six. In odd dimensions we describe Sasaki manifolds on which equality in the estimate is realized by Killing spinors with torsion. In dimension five we characterize all Killing spinors with torsion and obtain certain naturally reductive spaces as exceptional cases.
Painless Ovarian Torsion Mimicking a Uterine Myoma
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Cheng-Kuo Lin
2006-12-01
Conclusion: Ovarian torsion is a significant cause of acute lower abdominal pain in women and is a gynecologic surgical emergency. Nevertheless, surgical strategies are usually impeded because of ambiguous warning signs. Clinicians may be misled by certain conditions such as silent ovarian torsion. Although there may be no specific indication, the diagnosis of ovarian torsion should be considered on finding a pelvic mass.
The odd side of torsion geometry
DEFF Research Database (Denmark)
Conti, Diego; Madsen, Thomas Bruun
2012-01-01
We introduce and study a notion of `Sasaki with torsion structure' (ST) as an odd-dimensional analogue of Kähler with torsion geometry (KT). These are normal almost contact metric manifolds that admit a unique compatible connection with 3-form torsion. Any odd-dimensional compact Lie group is sho...
Test rig for tension-torsion at high temperature
International Nuclear Information System (INIS)
Policella, H.; Pacou, D.
1988-01-01
An improved version of Tension-Torsion test rig at high temperature (1,000 0 C) is described. Damage under Multiaxial loading, experimental methods have been developed concerning both extensometric measures and induction heating application. First experimental results are presented for AISI316 nuclear steel at 600 0 C and INCO718 alloy at 650 and 550 0 C. During these tests, the Multiaxiality effect is investigated following proportional or non proportional strain (or stress) paths (phase or out of phase) [fr
Calibration of combined bending-torsion fatigue reliability data reduction
Kececioglu, D.; Mcconnell, J. B.
1969-01-01
The combined bending-torsion fatigue reliability research machines are described. Three such machines are presently in operation. The calibration of these machines is presented in depth. Fatigue data generated with these machines for SAE 4340 steel grooved specimens subjected to reversed bending and steady torque loading are given. The data reduction procedure is presented. Finally, some comments are made about notch sensitivity and stress concentration as applied to combined fatigue.
THE RELIABILITY ANALYSIS OF EXISTING REINFORCED CONCRETE PILES IN PERMAFROST REGIONS
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Vladimir S. Utkin
2017-06-01
Full Text Available The article describes the general problem of safe operation of buildings and structures with the dynamics of permafrost in Russia and other countries. The global warming on Earth will lead to global disasters such as failures of buildings and structures. The main reason of these failures will be a reduction of bearing capacity and the reliability of foundations. It is necessary to organize the observations (monitoring for the process of reducing the bearing capacity of foundations to prevent such accidents and reduce negative consequences, to development of preventive measures and operational methods for the piles reliability analysis. The main load-bearing elements of the foundation are reinforced concrete piles and frozen ground. Reinforced concrete piles have a tendency to decrease the bearing capacity and reliability of the upper (aerial part and the part in the soil. The article discusses the problem of reliability analysis of existing reinforced concrete piles in upper part in permafrost regions by the reason of pile degradation in the contact zone of seasonal thawing and freezing soil. The evaluation of the probability of failure is important in itself, but also it important for the reliability of foundation: consisting of piles and frozen soil. Authors offers the methods for reliability analysis of upper part of reinforced concrete piles in the contact zone with seasonally thawed soil under different number of random variables (fuzzy variables in the design mathematical model of a limit state by the strength criterion.
Net-section-collapse of circumferentially cracked cylinders subjected to torsional moment
International Nuclear Information System (INIS)
Miura, Naoki; Hoshino, Katsuaki; Li, Yinsheng; Doi, Hiroaki
2011-01-01
When a flaw is detected in austenitic piping during in-service inspection, the limit load criterion given in the codes such as JSME Rules on Fitness-for-Service for Nuclear Power Plants or ASME Boiler and Pressure Vessel Code Section XI can be applied to evaluate the structural integrity of the piping. Considering that a cracked pipe is subjected to tensile load and/or bending moment, limit load (moment) for ductile material can be well predicted based on the net-section-collapse criterion derived from the equilibrium of the admissible stress distribution on the ligament of the cracked section. Actual piping is generally subjected to combined tensile, bending, and torsional loadings, however, a methodology to evaluate limit moment for torsion is not established due to the inadequacy of experimental validation. In this study, fracture tests for circumferentially cracked cylinders subjected to torsional moment were conducted. Tested material was austenitic stainless steel, and the shape and size of crack were variable. Experimental maximum moments were compared with the limit moments, which were evaluated based on the concept of the net-section-collapse criterion for torsional moment. The maximum moments could be conservatively predicted by the net-section-collapse criterion. In addition, an innovative test method was developed to conduct torsional tests using a pair of Charpy V-notch specimens and a conventional test machine. The adequacy of the replacement of cracks with machined notches for ductile materials under torsional loading was investigated through the comparison of the fracture behavior obtained from notched and precracked Charpy specimens. The developed method could be an alternative test method for torsional moment. (author)
Design and Preparation of Carbon Based Composite Phase Change Material for Energy Piles.
Yang, Haibin; Memon, Shazim Ali; Bao, Xiaohua; Cui, Hongzhi; Li, Dongxu
2017-04-07
Energy piles-A fairly new renewable energy concept-Use a ground heat exchanger (GHE) in the foundation piles to supply heating and cooling loads to the supported building. Applying phase change materials (PCMs) to piles can help in maintaining a stable temperature within the piles and can then influence the axial load acting on the piles. In this study, two kinds of carbon-based composite PCMs (expanded graphite-based PCM and graphite nanoplatelet-based PCM) were prepared by vacuum impregnation for potential application in energy piles. Thereafter, a systematic study was performed and different characterization tests were carried out on two composite PCMs. The composite PCMs retained up to 93.1% of paraffin and were chemically compatible, thermally stable and reliable. The latent heat of the composite PCM was up to 152.8 J/g while the compressive strength of cement paste containing 10 wt % GNP-PCM was found to be 37 MPa. Hence, the developed composite PCM has potential for thermal energy storage applications.
TORSION OF THE VERMIFORM APPENDIX: A CASE REPORT
Directory of Open Access Journals (Sweden)
Dr. Imtiaz Wani
2009-07-01
Full Text Available Torsion of the vermiform appendix is a rare condition with few cases reported in the literature. Various factors predispose to torsion. Various factors predispose to torsion. We report a case of primary torsion of the vermiform appendix. The clinical presentation was indistinguishable from acute appendicitis and the diagnosis was made at operation. Appendix was preileal in position and the direction of torsion was anticlockwise. There was intrinsic torsion with no obvious factor for torsion identified. Appendectomy was performed.
Directory of Open Access Journals (Sweden)
Wengang Zhang
2016-01-01
Full Text Available Piles are long, slender structural elements used to transfer the loads from the superstructure through weak strata onto stiffer soils or rocks. For driven piles, the impact of the piling hammer induces compression and tension stresses in the piles. Hence, an important design consideration is to check that the strength of the pile is sufficient to resist the stresses caused by the impact of the pile hammer. Due to its complexity, pile drivability lacks a precise analytical solution with regard to the phenomena involved. In situations where measured data or numerical hypothetical results are available, neural networks stand out in mapping the nonlinear interactions and relationships between the system's predictors and dependent responses. In addition, unlike most computational tools, no mathematical relationship assumption between the dependent and independent variables has to be made. Nevertheless, neural networks have been criticized for their long trial-and-error training process since the optimal configuration is not known a priori. This paper investigates the use of a fairly simple nonparametric regression algorithm known as multivariate adaptive regression splines (MARS, as an alternative to neural networks, to approximate the relationship between the inputs and dependent response, and to mathematically interpret the relationship between the various parameters. In this paper, the Back propagation neural network (BPNN and MARS models are developed for assessing pile drivability in relation to the prediction of the Maximum compressive stresses (MCS, Maximum tensile stresses (MTS, and Blow per foot (BPF. A database of more than four thousand piles is utilized for model development and comparative performance between BPNN and MARS predictions.
Steel Sheet Pile Walls in Soft Soil
Kort, D.A.
2002-01-01
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 issued in 1997. This code offers possibilities for cheaper and safer steel sheet piling, in comparison with the existing design criteria used in most countries. Two of these design criteria with w...
Hydraulic structures with defective sheet pile walls
Ahmed, Ashraf A.; Johnston, Harold T.; Oyedele, Lukumon
2013-01-01
A sheet pile wall driven to form a barrier wall below the floor of a hydraulic structure is frequently assumed to be watertight. Although the leakage through the interlocks of the sheet piles is usually small, damage and other factors can result in significant leakage. Consequently, this assumption is rarely, if ever, satisfied in reality. The present study used a finite-element model to investigate the effect of leaks through sheet piles driven under the floor of a hydraulic structure on see...
Underwater Sound Propagation from Marine Pile Driving.
Reyff, James A
2016-01-01
Pile driving occurs in a variety of nearshore environments that typically have very shallow-water depths. The propagation of pile-driving sound in water is complex, where sound is directly radiated from the pile as well as through the ground substrate. Piles driven in the ground near water bodies can produce considerable underwater sound energy. This paper presents examples of sound propagation through shallow-water environments. Some of these examples illustrate the substantial variation in sound amplitude over time that can be critical to understand when computing an acoustic-based safety zone for aquatic species.
Investigations on Torsion of the Two-Chords Single Laced Members
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Lorkowski Paweł
2017-06-01
Full Text Available The paper presents experimental and numerical studies to determine the equivalent second moment of area of the uniform torsion of the two-chord steel single laced members. The members are used as poles of railway traction network gates, and steel columns of framed buildings as well. The stiffness of uniform torsion of this kind of columns allows to the determine the critical loads of the spatial stability. The experimental studies have been realized on a single - span members with rotation arrested at their ends, loaded by a torque applied at the mid-span. The relationship between angle of rotation of the considered cross-section and the torque has been determined. Appropriate numerical model was created in the ABAQUS program, based on the finite element method. A very good compatibility has been observed between experimental and numerical studies. The equivalent second moment of area of the uniform torsion for analysed members has been determined by comparing the experimental and analytical results to those obtained from differential equation of non-uniform torsion, based on Vlasov’s theory. Additionally, the parametric analyses of similar members subjected to the uniform torsion, for the richer range of cross-sections have been carried out by the means of SOFiSTiK program. The purpose of the latter was determining parametrical formulas for calculation of the second moment of area of uniform torsion.
Investigations on Torsion of the Two-Chords Single Laced Members
Lorkowski, Paweł; Gosowski, Bronisław
2017-06-01
The paper presents experimental and numerical studies to determine the equivalent second moment of area of the uniform torsion of the two-chord steel single laced members. The members are used as poles of railway traction network gates, and steel columns of framed buildings as well. The stiffness of uniform torsion of this kind of columns allows to the determine the critical loads of the spatial stability. The experimental studies have been realized on a single - span members with rotation arrested at their ends, loaded by a torque applied at the mid-span. The relationship between angle of rotation of the considered cross-section and the torque has been determined. Appropriate numerical model was created in the ABAQUS program, based on the finite element method. A very good compatibility has been observed between experimental and numerical studies. The equivalent second moment of area of the uniform torsion for analysed members has been determined by comparing the experimental and analytical results to those obtained from differential equation of non-uniform torsion, based on Vlasov's theory. Additionally, the parametric analyses of similar members subjected to the uniform torsion, for the richer range of cross-sections have been carried out by the means of SOFiSTiK program. The purpose of the latter was determining parametrical formulas for calculation of the second moment of area of uniform torsion.
Torsions of 3-dimensional manifolds
Wurzbacher, T
2002-01-01
From the reviews: "This is an excellent exposition about abelian Reidemeister torsions for three-manifolds." ―Zentralblatt Math "This monograph contains a wealth of information many topologists will find very handy. …Many of the new points of view pioneered by Turaev are gradually becoming mainstream and are spreading beyond the pure topology world. This monograph is a timely and very useful addition to the scientific literature." ―Mathematical Reviews
Moduli space of torsional manifolds
International Nuclear Information System (INIS)
Becker, Melanie; Tseng, L.-S.; Yau, S.-T.
2007-01-01
We characterize the geometric moduli of non-Kaehler manifolds with torsion. Heterotic supersymmetric flux compactifications require that the six-dimensional internal manifold be balanced, the gauge bundle be Hermitian Yang-Mills, and also the anomaly cancellation be satisfied. We perform the linearized variation of these constraints to derive the defining equations for the local moduli. We explicitly determine the metric deformations of the smooth flux solution corresponding to a torus bundle over K3
Influence of Torsion Effect on the Mechanical Characteristics of Reinforced Concrete Column
Wang, Debin; Fan, Guoxi
2017-11-01
The purpose of this paper is to study the effect of torsional effect and loading rate on the flexural capacity of RC members. Based on the fiber model of finite element software ABAQUS, a model has been established with the consideration of the strain rate sensitivity of steel and concrete. The model is used to reflect the influence of the rotational component of ground motion by applying the initial angular displacement. The mechanical properties of RC columns under monotonic loads are simulated. The simulation results show that there has been a decrease in the carrying capacity and initial stiffness of RC columns for high initial torsion angle. With the increase of initial torsion angle, the influence of loading rate on RC columns gradually increases.
Torsional resistance of retreatment instruments.
Lopes, Hélio P; Elias, Carlos N; Vedovello, Gislaine A F; Bueno, Carlos E S; Mangelli, Marcelo; Siqueira, José F
2011-10-01
This study compared the torsional resistance of two brands of rotary nickel-titanium (NiTi) instruments indicated for endodontic retreatment. Mtwo retreatment instruments #15 and #25 (VDW, Munich, Germany) and ProTaper Universal retreatment instruments D2 and D3 (Maillefer/Dentsply, Ballaigues, Switzerland) were subjected to a torsional assay in clockwise rotation. The two parameters evaluated were maximum torque and angular deflection at failure. Fractured instruments had their fractured surfaces and helical shafts examined by scanning electron microscopy. The results indicated that the angular deflection at fracture decreased in the following order: Mtwo retreatment file #15 > Mtwo retreatment file #25 > ProTaper Universal retreatment file D2 > ProTaper Universal retreatment file D3. As for the maximum torque values, the results revealed the following descending order: ProTaper Universal file D2 > Mtwo retreatment file #25 > ProTaper Universal file D3 > Mtwo retreatment file #15. Scanning electron microscopic analysis revealed that plastic deformation occurred along the helical shaft of the fractured instruments. Fractured surfaces were of the ductile type. The instruments tested showed different torsional behavior depending on the parameter evaluated. If one considers that high angular deflection values may serve as a safety factor, then the Mtwo retreatment instruments showed significantly better results. Copyright © 2011 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.
Bezci, Semih E; Eleswarapu, Ananth; Klineberg, Eric O; O'Connell, Grace D
2018-02-12
Stresses applied to the spinal column are distributed between the intervertebral disc and facet joints. Structural and compositional changes alter stress distributions within the disc and between the disc and facet joints. These changes influence the mechanical properties of the disc joint, including its stiffness, range of motion, and energy absorption under quasi-static and dynamic loads. There have been few studies evaluating the role of facet joints in torsion. Furthermore, the relationship between biochemical composition and torsion mechanics is not well understood. Therefore, the first objective of this study was to investigate the role of facet joints in torsion mechanics of healthy and degenerated human lumbar discs under a wide range of compressive preloads. To achieve this, each disc was tested under four different compressive preloads (300-1200 N) with and without facet joints. The second objective was to develop a quantitative structure-function relationship between tissue composition and torsion mechanics. Facet joints have a significant contribution to disc torsional stiffness (∼60%) and viscoelasticity, regardless of the magnitude of axial compression. The findings from this study demonstrate that annulus fibrosus GAG content plays an important role in disc torsion mechanics. A decrease in GAG content with degeneration reduced torsion mechanics by more than an order of magnitude, while collagen content did not significantly influence disc torsion mechanics. The biochemical-mechanical and compression-torsion relationships reported in this study allow for better comparison between studies that use discs of varying levels of degeneration or testing protocols and provide important design criteria for biological repair strategies. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.
Wang, Yuhang; Nie, Jianguo; Fan, Jiansheng
2016-06-01
An experimental study on concrete filled steel tube columns with rectangular section subjected to compressionflexure-torsion combined action has been carried out. The failure modes and load-deformation hysteretic relations were obtained. Based on the principles of classical material mechanics, the relations between the torsion curvature of the section and the shear strain of the fiber on the section were established. Then the strain distribution on the rectangular section of concrete filled steel tube columns subjected to torsion was analyzed. The three-dimensional refined finite element model was also built, in order to make the precision verification. The matrix forms of the relation between the torsion curvature of the section and the shear strain of the fiber on the section were derived, and introduced into the fiber beam model considering nonlinear torsion effect on the section. The comparison between test results and calculation results showed that the fiber beam model considering nonlinear torsion effect had high modeling efficiency and solution precision for predicting the torsion behavior of concrete filled steel tube columns with rectangular sections, and was suitable for analyzing the dynamic response of various structures subjected to the combined cyclic load caused by the earthquake load.
Cyclic Axial-Torsional Deformation Behavior of a Cobalt-Base Superalloy
Bonacuse, Peter J.; Kalluri, Sreeramesh
1995-01-01
The cyclic, high-temperature deformation behavior of a wrought cobalt-base super-alloy, Haynes 188, is investigated under combined axial and torsional loads. This is accomplished through the examination of hysteresis loops generated from a biaxial fatigue test program. A high-temperature axial, torsional, and combined axial-torsional fatigue database has been generated on Haynes 188 at 760 C. Cyclic loading tests have been conducted on uniform gage section tubular specimens in a servohydraulic axial-torsional test rig. Test control and data acquisition were accomplished with a minicomputer. The fatigue behavior of Haynes 188 at 760 C under axial, torsional, and combined axial-torsional loads and the monotonic and cyclic deformation behaviors under axial and torsional loads have been previously reported. In this paper, the cyclic hardening characteristics and typical hysteresis loops in the axial stress versus axial strain, shear stress ,versus engineering shear strain, axial strain versus engineering shear strain. and axial stress versus shear stress spaces are presented for cyclic in-phase and out-of-phase axial-torsional tests. For in-phase tests, three different values of the proportionality constant lambda (the ratio of engineering shear strain amplitude to axial strain amplitude, are examined, viz. 0.86, 1.73, and 3.46. In the out-of-phase tests, three different values of the phase angle, phi (between the axial and engineering shear strain waveforms), are studied, viz., 30, 60, and 90 degrees with lambda equals 1.73. The cyclic hardening behaviors of all the tests conducted on Haynes 188 at 760 C are evaluated using the von Mises equivalent stress-strain and the maximum shear stress-maximum engineering shear strain (Tresca) curves. Comparisons are also made between the hardening behaviors of cyclic axial, torsional, and combined in-phase (lambda = 1.73 and phi = 0) and out-of-phase (lambda = 1.73 and phi = 90') axial-torsional fatigue tests. These comparisons
Tensile and Torsional Structural Properties of the Native Scapholunate Ligament.
Pang, Eric Quan; Douglass, Nathan; Behn, Anthony; Winterton, Matthew; Rainbow, Michael J; Kamal, Robin N
2018-02-17
The ideal material for reconstruction of the scapholunate interosseous ligament (SLIL) should replicate the mechanical properties of the native SLIL to recreate normal kinematics and prevent posttraumatic arthritis. The purpose of our study was to evaluate the cyclic torsional and tensile properties of the native SLIL and load to failure tensile properties of the dorsal SLIL. The SLIL bone complex was resected from 10 fresh-frozen cadavers. The scaphoid and lunate were secured in polymethylmethacrylate and mounted on a test machine that incorporated an x-y stage and universal joint, which permitted translations perpendicular to the rotation/pull axis as well as nonaxial angulations. After a 1 N preload, specimens underwent cyclic torsional testing (±0.45 N m flexion/extension at 0.5 Hz) and tensile testing (1-50 N at 1 Hz) for 500 cycles. Lastly, the dorsal 10 mm of the SLIL was isolated and displaced at 10 mm/min until failure. During intact SLIL cyclic torsional testing, the neutral zone was 29.7° ± 6.6° and the range of rotation 46.6° ± 7.1°. Stiffness in flexion and extension were 0.11 ± 0.02 and 0.12 ± 0.02 N m/deg, respectively. During cyclic tensile testing, the engagement length was 0.2 ± 0.1 mm, the mean stiffness was 276 ± 67 N/mm, and the range of displacement was 0.4 ± 0.1 mm. The dorsal SLIL displayed a 0.3 ± 0.2 mm engagement length, 240 ± 65 N/mm stiffness, peak load of 270 ± 91 N, and displacement at peak load of 1.8 ± 0.3 mm. We report the torsional properties of the SLIL. Our novel test setup allows for free rotation and translation, which reduces out-of-plane force application. This may explain our observation of greater dorsal SLIL load to failure than previous reports. By matching the natural ligament with respect to its tensile and torsional properties, we believe that reconstructions will better restore the natural kinematics of the wrist and lead to improved outcomes. Future clinical studies should aim to investigate this
Newton-Cartan gravity and torsion
Bergshoeff, Eric; Chatzistavrakidis, Athanasios; Romano, Luca; Rosseel, Jan
2017-10-01
We compare the gauging of the Bargmann algebra, for the case of arbitrary torsion, with the result that one obtains from a null-reduction of General Relativity. Whereas the two procedures lead to the same result for Newton-Cartan geometry with arbitrary torsion, the null-reduction of the Einstein equations necessarily leads to Newton-Cartan gravity with zero torsion. We show, for three space-time dimensions, how Newton-Cartan gravity with arbitrary torsion can be obtained by starting from a Schrödinger field theory with dynamical exponent z = 2 for a complex compensating scalar and next coupling this field theory to a z = 2 Schrödinger geometry with arbitrary torsion. The latter theory can be obtained from either a gauging of the Schrödinger algebra, for arbitrary torsion, or from a null-reduction of conformal gravity.
Using torsion to manipulate spin currents
Fumeron, Sébastien; Berche, Bertrand; Medina, Ernesto; Santos, Fernando A. N.; Moraes, Fernando
2017-02-01
We address the problem of quantum particles moving on a manifold characterised by the presence of torsion along a preferential axis. In fact, such a torsion may be taylored by the presence of a single screw dislocation, whose Burgers vector measures the torsion amplitude. The problem, first treated in the relativistic limit describing fermions that couple minimally to torsion, is then analysed in the Pauli limit. We show that torsion induces a geometric potential and also that it couples generically to the phase of the wave function, giving rise to the possibility of using torsion to manipulate spin currents in the case of spinor wave functions. These results emerge as an alternative strategy for using screw dislocations in the design of spintronic-based devices.
Quartz crystal microbalance based on torsional piezoelectric resonators
International Nuclear Information System (INIS)
Buecking, W.; Du, B.; Turshatov, A.; Koenig, A. M.; Reviakine, I.; Bode, B.; Johannsmann, D.
2007-01-01
A quartz crystal microbalance (QCM) is described, which is based on a torsional resonator, rather than a conventional thickness-shear resonator. Typical applications are measurements of film thickness in the coating industry and monitoring of biofouling. The torsional QCM is about a factor of 100 less sensitive than the conventional QCM. On the other hand, it can probe film thicknesses in the range of hundreds of microns, which is impossible with the conventional QCM due to viscoelastic artifacts. Data acquisition and data analysis proceed in analogy to the conventional QCM. An indicator of the material's softness can be extracted from the bandwidth of the resonance. Within the small-load approximation, the frequency shift is independent of whether the sample is applied to the face or to the side of the cylinder. Details of the geometry matter if the viscoelastic properties of the sample are of interest
Quantum General Relativity, Torsion and Uncertainty Relations
de Sabbata, V.; Sivaram, C.; Borzeszkowski, H.-H. V.; Treder, H.-J.
It is shown that in gravitational theories with torsion one is led to commutation rules corresponding to Landau-Peierls type uncertainty relations.Translated AbstractQuantisierte allgemeine Relativitätstheorie, Torsion und UnschärferelationenEs wird gezeigt, daß man in Gravitationstheorien mit Torsion zu Vertauschungsregeln geführt wird, die Landau-Peierls-artigen Unschärferelationen entsprechen.
Tibial Torsion Among Filipinos: A Cadaveric Study
Directory of Open Access Journals (Sweden)
Villamin CAC
2012-07-01
Full Text Available Tibial torsion, the twisting of the tibia about its long axis, can affect rotational positioning in total knee replacement. This angle varies depending on the ethnicity of the subject. There are no published studies to date to determine the tibial torsion among Filipinos. In this study, 28 cadaveric limbs were examined. Our results show that the average tibial torsion among adult Filipinos is 28.9°.
Steel Sheet Pile Walls in Soft Soil
Kort, D.A.
2002-01-01
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
Detection of tube leaks in piles
Energy Technology Data Exchange (ETDEWEB)
Upson, U.L.
1960-01-20
This report discusses the use of liquid ammonia as a tracer for the detection of cooling water leaks into the piles. It is both safe and cheap and can be detected by methods adaptable to direct-reading instrumentation on a continuous-flow sample. Moderate capital costs and materials costs of less than $50 per pile test are anticipated.
Dirac operators and Killing spinors with torsion; Dirac-Operatoren und Killing-Spinoren mit Torsion
Energy Technology Data Exchange (ETDEWEB)
Becker-Bender, Julia
2012-12-17
On a Riemannian spin manifold with parallel skew torsion, we use the twistor operator to obtain an eigenvalue estimate for the Dirac operator with torsion. We consider the equality case in dimensions four and six. In odd dimensions we describe Sasaki manifolds on which equality in the estimate is realized by Killing spinors with torsion. In dimension five we characterize all Killing spinors with torsion and obtain certain naturally reductive spaces as exceptional cases.
High cycle torsional fatigue properties of 17-4PH stainless steel
Directory of Open Access Journals (Sweden)
K. Yanase
2016-07-01
Full Text Available Sensitivity to small defects under torsional fatigue loading condition is examined in the high cycle fatigue regime. Fatigue crack initiation and small crack growth behaviors were observed during fatigue testing and fractographic investigations were performed. The results are compared to the data obtained in the uniaxial fatigue tests, which allows the effect of biaxial stresses on the surface of material to be discussed. Finally, an approach for predicting the fatigue limit of 17-4PH stainless steel under torsional and tension-compression fatigue loadings is presented.
Stress analysis and torsional buckling analysis of U-shaped bellows
International Nuclear Information System (INIS)
Watanabe, Osamu; Ohtsubo, Hideomi.
1986-01-01
This paper presents analysis of elastic stress and torsional buckling of U-shaped bellows using ring elements. The expansion joint is considered to be composed of the two toroidal sections and inner-connecting annular plates. The general thin shell theory is employed to derive strain-displacement relations of shells and plates, valid for any loadings. Numerical examples under internal pressure or axial loading are described and compared with the results of existing appropriate analysis. The fundamental aspects of torsional buckling, which have not been studied previously, will also be investigated. (author)
FEM Modelling of Lateral-Torsional Buckling Using Shell and Solid Elements
DEFF Research Database (Denmark)
Valeš, Jan; Stan, Tudor-Cristian
2017-01-01
The paper describes two methods of FEM modelling of I-section beams loaded by bending moments. Series of random realizations with initial imperfections following the first eigenmode of lateral-torsional buckling were created. Two independent FEM software products were used for analyses of resista......The paper describes two methods of FEM modelling of I-section beams loaded by bending moments. Series of random realizations with initial imperfections following the first eigenmode of lateral-torsional buckling were created. Two independent FEM software products were used for analyses...
Ultimate Strength of Ship Hulls under Torsion
DEFF Research Database (Denmark)
Paik, Jeom Kee; Thayamballi, Anil K.; Pedersen, Preben Terndrup
2001-01-01
subjected to torsion. A procedure for calculating these stresses is briefly described. As an illustrative example, the distribution and magnitude of warping and shear stresses for a typical container vessel hull cross section under unit torsion is calculated by the procedure. By theoretical and numerical...... analyses, it is shown that the influence of torsion induced warping stresses on the ultimate hull girder bending strength is small for ductile hull materials while torsion induced shear stresses will of course reduce the ship hull ultimate bending moment....
Primary splenic torsion in a Boston terrier
International Nuclear Information System (INIS)
Ohta, H.; Takagi, S.; Murakami, M.; Sasaki, N.; Yoshikawa, M.; Nakamura, K.; Hwang, S.J.; Yamasaki, M.; Takiguchi, M.
2009-01-01
A 7-year-old female Boston terrier was referred to Hokkaido University Veterinary Teaching Hospital with a history of hemoglobinuria and anemia for several days. Abdominal radiographs showed splenomegaly, and ultrasonography revealed a hypoechoic splenic parenchyma with interspersed linear echoes consistent with the ultrasonographic appearance of splenic torsion. Ultrasonography and computed tomography (CT) indicated a C-shaped spleen. Exploratory laparotomy confirmed the diagnosis of splenic torsion. A splenectomy was performed, and the dog recovered well without complications. This is the first report of splenic torsion in Boston terriers, and the usefulness of ultrasonographic and CT findings of the splenic torsion was also confirmed
Primary splenic torsion in a Boston terrier.
OHTA, Hiroshi; TAKAGI, Satoshi; MURAKAMI, Masahiro; SASAKI, Noboru; YOSHIKAWA, Muneyoshi; NAKAMURA, Kensuke; HWANG, Shiang-Jyi; YAMASAKI, Masahiro; TAKIGUCHI, Mitsuyoshi
2009-11-01
A 7-year-old female Boston terrier was referred to Hokkaido University Veterinary Teaching Hospital with a history of hemoglobinuria and anemia for several days. Abdominal radiographs showed splenomegaly, and ultrasonography revealed a hypoechoic splenic parenchyma with interspersed linear echoes consistent with the ultrasonographic appearance of splenic torsion. Ultrasonography and computed tomography (CT) indicated a C-shaped spleen. Exploratory laparotomy confirmed the diagnosis of splenic torsion. A splenectomy was performed, and the dog recovered well without complications. This is the first report of splenic torsion in Boston terriers, and the usefulness of ultrasonographic and CT findings of the splenic torsion was also confirmed.
Laboratory and field study of the performance of helical piles in sandy soil
Directory of Open Access Journals (Sweden)
Farhad Nabizadeh
2016-12-01
Full Text Available Developing different method in construction of deep footing plays a major role in optimized and economized performing of civil projects especially in problematic soils. One of the common types of deep footing is helical piles which have several advantages such as fast procedure, useful in different soil types, performing without noise and vibration, effective in pressure and tension and etc. In this paper, the performance of 1-helix & 2-helixes and 3-helixes in an un-grouted and grouted with the field and laboratory studies are discussed. Field studies include of helical piles behavior in sand. Laboratory tests with physical FCV modeling is also carried out on the soil of the site. Grouting effect on helical piles resistance is evaluated. Comparison load test results with analytical method were compared. Results show that performance cylindrical in sandy soils in helical piles is not suitable and increasing helical number pile capacity is decreases. Also, after grouting helical pile with three helixes increases more resistant compare to one helix and double helixes.
Faizah Bawadi, Nor; Anuar, Shamilah; Rahim, Mustaqqim A.; Mansor, A. Faizal
2018-03-01
A conventional and seismic method for determining the ultimate pile bearing capacity was proposed and compared. The Spectral Analysis of Surface Wave (SASW) method is one of the non-destructive seismic techniques that do not require drilling and sampling of soils, was used in the determination of shear wave velocity (Vs) and damping (D) profile of soil. The soil strength was found to be directly proportional to the Vs and its value has been successfully applied to obtain shallow bearing capacity empirically. A method is proposed in this study to determine the pile bearing capacity using Vs and D measurements for the design of pile and also as an alternative method to verify the bearing capacity from the other conventional methods of evaluation. The objectives of this study are to determine Vs and D profile through frequency response data from SASW measurements and to compare pile bearing capacities obtained from the method carried out and conventional methods. All SASW test arrays were conducted near the borehole and location of conventional pile load tests. In obtaining skin and end bearing pile resistance, the Hardin and Drnevich equation has been used with reference strains obtained from the method proposed by Abbiss. Back analysis results of pile bearing capacities from SASW were found to be 18981 kN and 4947 kN compared to 18014 kN and 4633 kN of IPLT with differences of 5% and 6% for Damansara and Kuala Lumpur test sites, respectively. The results of this study indicate that the seismic method proposed in this study has the potential to be used in estimating the pile bearing capacity.
Load-Displacement and Stability Characteristics of Thin-Walled ...
African Journals Online (AJOL)
Further, the same refinements were applied to the reduced formulations which contain only lateral and torsional degrees of freedom, and these have been applied for the determination of lateral torsional buckling loads and for plotting linearized load-displacement curves. These studies showed that only the channel ...
In-pile experimental device for Sirene thermionic converters
International Nuclear Information System (INIS)
Bliaux, J.; Durand, J.; Lazare-Chopard, G.
1969-01-01
The irradiation device described here, was built for in pile life tests of 100 We SIRENE converters. The nuclear converter is located in a sealed vacuum chamber, which is plugged at the lower end of a coaxial tubing acting as electrical leads. The output power is available on a variable resistive load on the bank of the reactor pool. Thermal, electrical and neutronic parameters of the converter are recorded. Since 1967, two permanent devices allowed five experiments in the swimming pool TRITON (CEN-FAR) and the results, obtained till now, are presented. (authors) [fr
Design and Preparation of Carbon Based Composite Phase Change Material for Energy Piles
Directory of Open Access Journals (Sweden)
Haibin Yang
2017-04-01
Full Text Available Energy piles—A fairly new renewable energy concept—Use a ground heat exchanger (GHE in the foundation piles to supply heating and cooling loads to the supported building. Applying phase change materials (PCMs to piles can help in maintaining a stable temperature within the piles and can then influence the axial load acting on the piles. In this study, two kinds of carbon-based composite PCMs (expanded graphite-based PCM and graphite nanoplatelet-based PCM were prepared by vacuum impregnation for potential application in energy piles. Thereafter, a systematic study was performed and different characterization tests were carried out on two composite PCMs. The composite PCMs retained up to 93.1% of paraffin and were chemically compatible, thermally stable and reliable. The latent heat of the composite PCM was up to 152.8 J/g while the compressive strength of cement paste containing 10 wt % GNP-PCM was found to be 37 MPa. Hence, the developed composite PCM has potential for thermal energy storage applications.
Design and Preparation of Carbon Based Composite Phase Change Material for Energy Piles
Yang, Haibin; Memon, Shazim Ali; Bao, Xiaohua; Cui, Hongzhi; Li, Dongxu
2017-01-01
Energy piles—A fairly new renewable energy concept—Use a ground heat exchanger (GHE) in the foundation piles to supply heating and cooling loads to the supported building. Applying phase change materials (PCMs) to piles can help in maintaining a stable temperature within the piles and can then influence the axial load acting on the piles. In this study, two kinds of carbon-based composite PCMs (expanded graphite-based PCM and graphite nanoplatelet-based PCM) were prepared by vacuum impregnation for potential application in energy piles. Thereafter, a systematic study was performed and different characterization tests were carried out on two composite PCMs. The composite PCMs retained up to 93.1% of paraffin and were chemically compatible, thermally stable and reliable. The latent heat of the composite PCM was up to 152.8 J/g while the compressive strength of cement paste containing 10 wt % GNP-PCM was found to be 37 MPa. Hence, the developed composite PCM has potential for thermal energy storage applications. PMID:28772752
Torsional Vibration in the National Wind Technology Center’s 2.5-Megawatt Dynamometer
Energy Technology Data Exchange (ETDEWEB)
Sethuraman, Latha [National Renewable Energy Lab. (NREL), Golden, CO (United States); Keller, Jonathan [National Renewable Energy Lab. (NREL), Golden, CO (United States); Wallen, Robb [National Renewable Energy Lab. (NREL), Golden, CO (United States)
2016-08-31
This report documents the torsional drivetrain dynamics of the NWTC's 2.5-megawatt dynamometer as identified experimentally and as calculated using lumped parameter models using known inertia and stiffness parameters. The report is presented in two parts beginning with the identification of the primary torsional modes followed by the investigation of approaches to damp the torsional vibrations. The key mechanical parameters for the lumped parameter models and justification for the element grouping used in the derivation of the torsional modes are presented. The sensitivities of the torsional modes to different test article properties are discussed. The oscillations observed from the low-speed and generator torque measurements were used to identify the extent of damping inherently achieved through active and passive compensation techniques. A simplified Simulink model of the dynamometer test article integrating the electro-mechanical power conversion and control features was established to emulate the torque behavior that was observed during testing. The torque response in the high-speed, low-speed, and generator shafts were tested and validated against experimental measurements involving step changes in load with the dynamometer operating under speed-regulation mode. The Simulink model serves as a ready reference to identify the torque sensitivities to various system parameters and to explore opportunities to improve torsional damping under different conditions.
Torsional behaviour of reinforced concrete beams with ferrocement U-jacketing—Experimental study
Directory of Open Access Journals (Sweden)
Gopal Charan Behera
2016-06-01
Full Text Available Wrapping technology is one of the effective ways of strengthening concrete elements. Several researchers reported the effectiveness of Glass fiber reinforced polymers and carbon fiber reinforced polymers for improving the strength of the concrete elements. Wrapping on three sides is one of the effective methods for strengthening the beams supporting slabs. Available literatures on the strength enhancement of “U” wrapped concrete elements subjected to torsional loads do not give a detailed insight, whereas this investigation is an attempt to address the issues with ferrocement “U” wrap. Ferrocement “U” wraps are preferred over FRPs because of its cost factor. The “U” wraps are found to provide better torque carrying capacity under all states of torsion while under reinforced members provide better toughness over other states of torsion. Similarly completely over reinforced beams provide more torque resisting capacity than the others. Increase of torsional capacity is more prominent in states of torsion while improvement in torsional strength with number of mesh layers in ferrocement “U” wrap is minimal.
Simultaneous acute appendicitis with right testicular torsion
Directory of Open Access Journals (Sweden)
Tanveer Akhtar
2012-01-01
Full Text Available We present a child with both acute appendicitis and torsion of the right testis presenting at the same time. Testicular torsion possibly occurring due to vomiting in acute appendicitis so far has not been reported in the literature.
Teenage testicular torsion. | Onuigbo | International Journal of ...
African Journals Online (AJOL)
Aim: To study testicular torsion in teenagers in the Igbo community. Method: A retrospective study was carried out as regards requests for pathological examination of specimens received at a Regional Reference Laboratory based in Enugu. Results: Over a period of 30 years, 28 surgical specimens of testicular torsion in ...
Misdiagnosed Adult Testicular Torsion: Case Report | Ndaguatha ...
African Journals Online (AJOL)
Adult testicular torsion is thought to be rare if not relatively unusual. The rarity could be an underestimation since there are many episodes of missed torsions and misdiagnosis with other conditions of acute scrotum despite the now widespread ultra sound availability that are being reported in the literature. Such a ...
Appendicular Torsion | Dubhashi | Nigerian Journal of Surgery
African Journals Online (AJOL)
. It can be primary or secondary. This is a case report of 52-year-old female with 180° anti-clockwise rotation of the appendix. Torsion can further leads to strangulation and infarction of the organ. Appendicular torsion could be included in the ...
Allowable temperature rise in tubes of the piles: Precautions against boiling
Energy Technology Data Exchange (ETDEWEB)
Woods, W.K.
1945-09-27
In the design of the pile, it was considered advisable never to impose so great a heat load on any tube that the available header pressure would be insufficient to sweep the tube free of vapor if boiling should accidentally be initiated in the tube. Figures are given for the maximum temperature rises permissible, as function of header pressure and orifice diameter.
Energy Technology Data Exchange (ETDEWEB)
Furet, J. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires
1962-07-01
We have been led to study the problem of safety in atomic pile control as a result of our participation on the one hand in the planning of C.E.A. atomic piles, and on the other hand in the pile safety sub omission considering atomic pile safety of operational or planned C.E.A. piles. We have thus had to consider the wishes occurring in piles during their operation and also their behaviour in the dynamic state The present work deals mainly with the importance of intrinsic safety devices, with the influence of reactivity variations on the power fluctuations during accidental operation, and with the development of robust and reliable safety appliances. The starting p accident has been especially studied both for low-flux piles where a compromise is necessary between the response time of the safety appliances and the statistical fluctuations and for high lux piles where xenon poisoning has an effect on the lower limit of the velocity of reactivity liberation. The desirability has been stressed of automation as a safety factor in atomic pile control. The details required for an understanding of the diagrams of the apparatus are given. (author) [French] Nous avons aborde le probleme de la securite dans le controle des piles atomiques a la suite de notre participation d'une part aux avant rojets de piles atomiques du CE.A. et d'autre part a l'examen au sein de la sous ommission de surete des piles, de la securite des piles du CE.A. en fonctionnement ou en projet. Nous avons ete amenes a nous interesser alors aux risques encourus par les piles pendant leur fonctionnement et par la meme a leur comportement en regime dynamique. Ce travail traite principalement de l'importance des securites intrinseques, de l'influence des variations de reactivite sur les evolutions de puissance en regime d'accident et du developpement d'appareillages de securite robustes et de fonctionnement tres sur. L'accident de demarrage a ete particulierement
Reliability-Based Design and Quality Control of Bored Piles
Bach, D.
2014-01-01
Bored piles are a type of deep foundations which have been and are being widely used in construction engineering such as high-rise buildings, bridges, jetties, and so on. Although bored piles have remarkable advantages over driven piles, the quality of bored piles is frequently affected by many
Wang, Pu; Huang, Zhen
2017-01-01
This paper uses experimental investigation and theoretical derivation to study the unified failure mechanism and ultimate capacity model of reinforced concrete (RC) members under combined axial, bending, shear and torsion loading. Fifteen RC members are tested under different combinations of compressive axial force, bending, shear and torsion using experimental equipment designed by the authors. The failure mechanism and ultimate strength data for the four groups of tested RC members under di...
Kerrigan, Shannon M; Kapatkin, Amy S; Garcia, Tanya C; Robinson, Duane A; Guzman, David Sanchez-Migallon; Stover, Susan M
2018-04-01
OBJECTIVE To describe the torsional and axial compressive properties of tibiotarsal bones of red-tailed hawks (Buteo jamaicensis). SAMPLE 16 cadaveric tibiotarsal bones from 8 red-tailed hawks. PROCEDURES 1 tibiotarsal bone from each bird was randomly assigned to be tested in torsion, and the contralateral bone was tested in axial compression. Intact bones were monotonically loaded in either torsion (n = 8) or axial compression (8) to failure. Mechanical variables were derived from load-deformation curves. Fracture configurations were described. Effects of sex, limb side, and bone dimensions on mechanical properties were assessed with a mixed-model ANOVA. Correlations between equivalent torsional and compressive properties were determined. RESULTS Limb side and bone dimensions were not associated with any mechanical property. During compression tests, mean ultimate cumulative energy and postyield energy for female bones were significantly greater than those for male bones. All 8 bones developed a spiral diaphyseal fracture and a metaphyseal fissure or fracture during torsional tests. During compression tests, all bones developed a crushed metaphysis and a fissure or comminuted fracture of the diaphysis. Positive correlations were apparent between most yield and ultimate torsional and compressive properties. CONCLUSIONS AND CLINICAL RELEVANCE The torsional and axial compressive properties of tibiotarsal bones described in this study can be used as a reference for investigations into fixation methods for tibiotarsal fractures in red-tailed hawks. Although the comminuted and spiral diaphyseal fractures induced in this study were consistent with those observed in clinical practice, the metaphyseal disruption observed was not and warrants further research.
2015-07-01
The overall goal of this project is the experimental evaluation and design of unfilled and concrete-filled FRP composite piles for load-bearing in bridges. This report covers Task 4B, Materials and Construction Specifications. : This technical report...
Soil heating during burning of forest slash piles and wood piles
Matt D. Busse; Carol J. Shestak; Ken R. Hubbert
2013-01-01
Pile burning of conifer slash is a common fuel reduction practice in forests of the western United States that has a direct, yet poorly quantified effect on soil heating. To address this knowledge gap, we measured the heat pulse beneath hand-built piles ranging widely in fuel composition and pile size in sandy-textured soils of the Lake Tahoe Basin. The soil heat pulse...
Directory of Open Access Journals (Sweden)
M. A. Algorafi
2011-07-01
Full Text Available Externally Prestressed Segmented (EPS concrete beams are generally used in the construction of bridge structures. External Prestressed technique uses tendons that are placed completely outside the concrete section and attached to the concrete at anchorages and deviators only. Segmented bridge is a bridge built in short sections. Segmented bridge applies smart technique that is a part of an engineering management. EPS bridges are affected by combined stresses i.e., bending, shear, normal, and torsion stresses especially at the segments interface joints. Previous studies on EPS bridges did not include the effect of torsion in the load carrying capacity and other structural behavior. This paper presents an experimental investigation of the structural behavior of EPS bridged under combined bending, shear, normal, and torsion stresses. The aim of this paper is to improve the existing equation to include the effect of torsion in estimating the failure load of EPS bridge. A parametric study was carried out to investigate the effect of different external tendon layouts and different levels of torsion.
Displacement pile installation effects in sand
Beijer-Lundberg, A.
2015-01-01
Installation effects govern the post-installation behaviour of displacement piles in sand. These effects are currently not completely understood. Suitable experimental techniques to model these installation effects include field, laboratory and experimental models. In the current thesis a
Performance of pile supported sign structures : [brief].
2015-05-01
Sign structures in Wisconsin are typically supported by drilled shaft foundations or spread : footing foundations. However, when the soil conditions are not suitable to be supported on : drilled shafts or spread footings, a group of piles could suppo...
New trends in pile safety instrumentation
International Nuclear Information System (INIS)
Furet, J.
1961-01-01
This report addresses the protection of nuclear piles against damages due to operation incidents. The author discusses the current trends in the philosophy of safety of atomic power piles, identifies the parameters which define safety systems, presents tests to be performed on safety chains, comments the relationship between safety and the decrease of the number of pile inadvertent shutdowns, discusses the issues of instrument failures and chain multiplicity, comments the possible improvement of the operation of elements which build up safety chains (design simplification, development of semiconductors, replacement of electromechanical relays by static relays), the role of safety logical computers and the development of automatics in pile safety, presents automatic control as a safety factor (example of automatic start-up), and finally comments the use of fuses
ATLAS Pile-up and Overlay Simulation
Novak, Tadej; The ATLAS collaboration
2017-01-01
The high luminosity of the LHC results in a significant background to interesting physics events known as pile-up. ATLAS uses several methods for simulating the effects of pile-up. The mostly used method is a direct simulation of background events where multiple simulated background events are combined for each physics event. For some physics processes, a more accurate simulation can be achieved by overlaying real proton-proton collisions on a simulated hard-scatter process. Overlay is also being investigated for a premixed pile-up background to reduce CPU usage and I/O stress during the simulation. Embedding replaces the muons found in Z→mumu decays in data with simulated taus at the same 4-momenta, thus preserving the underlying event and pileup from the original data event. This talk compares the pile-up simulation methods used at the ATLAS experiment pointing their benefits and drawbacks.
Discussion on elastic compressive-flexural-torsional buckling in structural members
Van der Put, T.A.C.M.
The article of Raven, Blaauwendraad and Vambersky in HERON 53, No. 1 discusses stability checking of torsional buckling in structural members loaded by compressive forces and bending moments. Unfortunately, many important issues are not considered and need to be commented on.
Tulebekova, S.; Saliyev, D.; Zhang, D.; Kim, J. R.; Karabay, A.; Turlybek, A.; Kazybayeva, L.
2017-11-01
Compressed air energy storage technology is one of the promising methods that have high reliability, economic feasibility and low environmental impact. Current applications of the technology are mainly limited to energy storage for power plants using large scale underground caverns. This paper explores the possibility of making use of reinforced concrete pile foundations to store renewable energy generated from solar panels or windmills attached to building structures. The energy will be stored inside the pile foundation with hollow sections via compressed air. Given the relatively small volume of storage provided by the foundation, the required storage pressure is expected to be higher than that in the large-scale underground cavern. The high air pressure typically associated with large temperature increase, combined with structural loads, will make the pile foundation in a complicated loading condition, which might cause issues in the structural and geotechnical safety. This paper presents a preliminary analytical study on the performance of the pile foundation subjected to high pressure, large temperature increase and structural loads. Finite element analyses on pile foundation models, which are built from selected prototype structures, have been conducted. The analytical study identifies maximum stresses in the concrete of the pile foundation under combined pressure, temperature change and structural loads. Recommendations have been made for the use of reinforced concrete pile foundations for renewable energy storage.
Grouting of uranium mill tailings piles
International Nuclear Information System (INIS)
Boegly, W.J. Jr.; Tamura, T.; Williams, J.D.
1984-03-01
A program of remedial action was initiated for a number of inactive uranium mill tailings piles. These piles result from mining and processing of uranium ores to meet the nation's defense and nuclear power needs and represent a potential hazard to health and the environment. Possible remedial actions include the application of covers to reduce radon emissions and airborne transport of the tailings, liners to prevent groundwater contamination by leachates from the piles, physical or chemical stabilization of the tailings, or moving the piles to remote locations. Conventional installation of liners would require excavation of the piles to emplace the liner; however, utilization of grouting techniques, such as those used in civil engineering to stabilize soils, might be a potential method of producing a liner without excavation. Laboratory studies on groutability of uranium mill tailings were conducted using samples from three abandoned piles and employing a number of particulate and chemical grouts. These studies indicate that it is possible to alter the permeability of the tailings from ambient values of 10 -3 cm/s to values approaching 10 -7 cm/s using silicate grouts and to 10 -8 cm/s using acrylamide and acrylate grouts. An evaluation of grouting techniques, equipment required, and costs associated with grouting were also conducted and are presented. 10 references, 1 table
Out of pile testing of the PHWR fuel bundles
International Nuclear Information System (INIS)
Mahender Dev; Raghunathan, S.; Agarwal, G.K.; Patel, R.J.; Agarwal, R.G.
2002-01-01
In PHWRs fuel bundle resides in the form of a string in the coolant channels. These fuel bundles are required to be replaced periodically with the help of fuelling machine and spent fuel is discharged to the spent-fuel bay through fuel transfer system. During complete refuelling operation, and during residence in channel fuel bundle experiences various kinds of loads like drag force, impact force, force applied by Fuelling Machine ram and force applied by various actuators in fuel transfer system. These fuel bundles are manufactured indigenously and require out of pile testing for qualification of design as well as manufacturing process. In 220 MWe PHWRs, 19-element split spacer fuel bundle is used whereas in 500 MWe PHWRs 37-element fuel bundle will be used. A comprehensive programme was conducted to generate, basic data like estimation of loads coming on fuel bundles, experimental data generation about friction factor and pressure drop and carrying out of pile testing of 19-element fuel bundles in Integral Thermal Facility at Hall-7. The 37-element fuel bundles were tested in fuel locator test facility at simulated reactor conditions for pressure drop test, endurance test and cross flow test. The 37-element bundles have also been tested for flow-induced vibration during residence in the reactor. The paper describes the experimental techniques and setups, for simulating the reactor condition and determining the effect of those conditions on the fuel bundles. (author)
Ter-Martirosyan, Z. G.; Ter-Martirosyan, A. Z.; Anzhelo, G. O.; Buslov, A. S.
2018-01-01
The task of the interaction of the sand and gravel drain pile with the surrounding loam soil after its preliminary deep compaction and formation of the composite ground cylinder from the drain pile and surrounding compacted loam soil (cells) is considered in the article. It is seen that the subsidence and carrying capacity of such cell considerably depends on physical and mechanical properties of the compacted drain piles and surrounding loam soil as well as their diameter and intercellular distance. The strain-stress state of the cell is considered not taking into account its component elements, but taking into account linear and elastic-plastic properties of the drain pile and creep flow of the surrounding loam soil. It is stated that depending on these properties the distribution and redistribution of the load on a cell takes place from the foundation raft between the drain pile and surrounding soil. Based on the results of task solving the formulas and charts are given demonstrating the ratio of the load between the drain pile and surrounding loam soil in time.
Torsion of the vermiform appendix: A case report | Wani | Internet ...
African Journals Online (AJOL)
Torsion of the vermiform appendix is a rare condition with few cases reported in the literature. Various factors predispose to torsion. Various factors predispose to torsion. We report a case of primary torsion of the vermiform appendix. The clinical presentation was indistinguishable from acute appendicitis and the diagnosis ...
Acute and intermittent testicular torsion: Analysis of presentation ...
African Journals Online (AJOL)
Background: Testicular torsion compromises the blood supply to the testes and may result in testicular loss or damage if not dealt with promptly. It can occur either as acute testicular torsion (ATT) or intermittent testicular torsion (ITT). This study examines the presentation, management, and outcome of adult testicular torsion.
Measurement of tibial torsion by computer tomography
International Nuclear Information System (INIS)
Jend, H.-H.; Heller, M.; Dallek, M.; Schoettle, H.
1981-01-01
A CT procedure for objective measurements of tibial torsion independent of axial rotation in the nearby joints is described. Transverse sections in defined planes of the tibia permit easy calculation of normal and abnormal congenital or posttraumatic angles of torsion. In 69 limbs normal tibial torsion was 40 0 +-9 0 . In a series of 42 limbs with complicated healing of a fracture of both bones of the leg it is shown that tibial maltorsion is a deformity which in most cases leads to arthrosis of the ankle joint. (Auth.)
Measurement of tibial torsion by computer tomography
Energy Technology Data Exchange (ETDEWEB)
Jend, H.H.; Heller, M.; Dallek, M.; Schoettle, H. (Hamburg Univ. (Germany, F.R.))
1981-01-01
A CT procedure for objective measurements of tibial torsion independent of axial rotation in the nearby joints is described. Transverse sections in defined planes of the tibia permit easy calculation of normal and abnormal congenital or posttraumatic angles of torsion. In 69 limbs normal tibial torsion was 40/sup 0/+-9/sup 0/. In a series of 42 limbs with complicated healing of a fracture of both bones of the leg it is shown that tibial maltorsion is a deformity which in most cases leads to arthrosis of the ankle joint.
Dynamic Instability of Pile-Supported Structures in Liquefiable Soils during Earthquakes
Directory of Open Access Journals (Sweden)
S. Adhikari
2008-01-01
Full Text Available Piles are long slender columns installed deep into the ground to support heavy structures such as oil platforms, bridges, and tall buildings where the ground is not strong enough to support the structure on its own. In seismic prone zones, in the areas of soft soils (loose to medium dense soil which liquefies like a quick sand piles are routinely used to support structures (buildings/ bridges. The pile and the building vibrate, and often collapse, in liquefiable soils during major earthquakes. In this paper an experimental and analytical approach is taken to characterize this vibration. The emphasis has been given to the dynamic instability of piled foundations in liquefied soil. The first natural frequency of a piled-structure vibrating in liquefiable soil is obtained from centrifuge tests. The experimental system is modelled using a fixed-free Euler-Bernoulli beam resting against an elastic support with axial load and tip mass with rotary inertia. Natural frequencies obtained from the analytical method are compared with experimental results. It was observed that the effective natural frequency of the system can reduce significantly during an earthquake.
A 4 mm² Double Differential Torsional MEMS Accelerometer Based on a Double-Beam Configuration.
Miao, Tongqiao; Xiao, Dingbang; Li, Qingsong; Hou, Zhanqiang; Wu, Xuezhong
2017-10-02
This paper reports the design and simulation of a 4 mm² double differential torsional MEMS accelerometer based on a double-beam configuration. Based on the structure of conventional torsional accelerometers, normally composed of one pair of proof masses and one torsional beam, this work explores the double differential configuration: a torsional accelerometer with two pairs of unbalanced proof masses rotating in reverse. Also, the torsional beam is designed as a double-beam structure, which is a symmetrical structure formed by two torsional beams separated by a certain distance. The device area of the novel accelerometer is more than 50 times smaller than that of a traditional double differential torsional MEMS accelerometer. The FEM simulation results demonstrate that the smaller device does not sacrifice other specifications, such as mechanical sensitivity, nonlinearity and temperature robustness. The mechanical sensitivity and nonlinearity of a ±15 g measuring range is 59.4 fF/g and 0.88%, respectively. Compared with traditional single-beam silicon structures, the novel structure can achieve lower maximum principle stress in critical regions and reduce the possibility of failure when high-g acceleration loading is applied along all three axes. The mechanical noise equivalent acceleration is about 0.13 mg / Hz in the theoretical calculations and the offset temperature coefficient is 0.25 mg/ ℃ in the full temperature range of - 40 ℃ to 60 ℃ .
Maizir, H.; Suryanita, R.
2018-01-01
A few decades, many methods have been developed to predict and evaluate the bearing capacity of driven piles. The problem of the predicting and assessing the bearing capacity of the pile is very complicated and not yet established, different soil testing and evaluation produce a widely different solution. However, the most important thing is to determine methods used to predict and evaluate the bearing capacity of the pile to the required degree of accuracy and consistency value. Accurate prediction and evaluation of axial bearing capacity depend on some variables, such as the type of soil, diameter, and length of pile, etc. The aims of the study of Artificial Neural Networks (ANNs) are utilized to obtain more accurate and consistent axial bearing capacity of a driven pile. ANNs can be described as mapping an input to the target output data. The method using the ANN model developed to predict and evaluate the axial bearing capacity of the pile based on the pile driving analyzer (PDA) test data for more than 200 selected data. The results of the predictions obtained by the ANN model and the PDA test were then compared. This research as the neural network models give a right prediction and evaluation of the axial bearing capacity of piles using neural networks.
Directory of Open Access Journals (Sweden)
Wojciech HOMIK
2011-01-01
Full Text Available The short explanation of usefulness of rubber torsional dampers in crankshaft in multi-cylinder engines is presented. The description of the construction and operation of rubber torsional damper is also included. In the rubber torsional damper, the damping is achieved as the effect of internal friction resulting from the deformation of the rubber material. This deformation appears while the internal rubber elasticity is overloaded. Both the physical and mechanical rubber properties depend on temperature change. In cooperation with rubber dampers manufacturer the experimental investigations are made in order to establish the influence of temperature change on torsional stiffness and damping.
Isolated torsion of fallopian tube. Radiological findings
International Nuclear Information System (INIS)
Tomas Fanjul, L.; Aldea Martinez, J.; Fernandez Matia, G.; Rodrigo Verguizas, J.; Fernandez Alvarez, G.; Galindo Vicente, M.C.
1993-01-01
Isolated tubal torsion is a very uncommon disorder that is rarely diagnosed preoperatively. We present a case and review the literature, which only provides ultrasonographic findings in 5 cases reported to date. 11 refs
Internal torsion resistance in deflected shafts
Directory of Open Access Journals (Sweden)
Mahmoud T. El-Sayed
2017-06-01
The objective of the present work was to estimate the effect of internal torsional resistance in shafts which is caused by deflection, for the reason that it has the upper hand on misalignment problem. With the aim of fulfilling this objective, an experimental rig has been constructed to verify the existence of the torsional resistance in deflected shafts and its variation with the rotation angle.
Torsion and geometrostasis in covariant superstrings
Energy Technology Data Exchange (ETDEWEB)
Zachos, C.
1985-01-01
The covariant action for freely propagating heterotic superstrings consists of a metric and a torsion term with a special relative strength. It is shown that the strength for which torsion flattens the underlying 10-dimensional superspace geometry is precisely that which yields free oscillators on the light cone. This is in complete analogy with the geometrostasis of two-dimensional sigma-models with Wess-Zumino interactions. 13 refs.
Torsion of Wandering Gallbladder following Colonoscopy
Directory of Open Access Journals (Sweden)
Sean R. Warfe
2013-01-01
Full Text Available Torsion of the gallbladder is an uncommon condition that may present as an acute abdomen. Its preoperative diagnosis can often be challenging due to its variable presentation, with specific sonographic signs seen infrequently. We describe, to our knowledge, the first case of torsion of a wandering gallbladder following a colonoscopy in a 69-year-old female who presented with acute abdominal pain after procedure. This was discovered intraoperatively, and after a subsequent cholecystectomy, she had an uncomplicated recovery.
Evaluation of Load-Displacement Relationships for Non-Slender Monopiles in Sand
DEFF Research Database (Denmark)
Sørensen, Søren Peder Hyldal; Møller, M.; Brødbæk, K. T.
pipe piles subjected to lateral loads at a given vertical eccentricity. The piles are heavily instrumented with strain gauges in order to obtain p-y curves and bending moment distributions along the piles. In order to minimise scale effects the tests are successfully carried out in a pressure tank...... to 6 m are typically necessary. In current practice these piles are normally designed by use of the p-y curve method although the method is developed and verified for small-diameter, slender piles with diameters up to approximately 2 m. This paper investigate the behaviour of two non-slender aluminium......; in current design the initial stiffness of the p-y curves is considered independent of the pile diameter. This recommendation is questionable as derived p-y curves indicate a strong dependency on pile diameter with a higher initial stiffness related to the largest pile diameter....
Attentional Modulation of Eye Torsion Responses
Stevenson, Scott B.; Mahadevan, Madhumitha S.; Mulligan, Jeffrey B.
2016-01-01
Eye movements generally have both reflexive and voluntary aspects, but torsional eye movements are usually thought of as a reflexive response to image rotation around the line of sight (torsional OKN) or to head roll (torsional VOR). In this study we asked whether torsional responses could be modulated by attention in a case where two stimuli rotated independently, and whether attention would influence the latency of responses. The display consisted of rear-projected radial "pinwheel" gratings, with an inner annulus segment extending from the center to 22 degrees eccentricity, and an outer annulus segment extending from 22 degrees out to 45 degrees eccentricity. The two segments rotated around the center in independent random walks, stepping randomly 4 degrees clockwise or counterclockwise at 60 Hz. Subjects were asked to attend to one or the other while keeping fixation steady at the center of the display. To encourage attention on one or the other segment of the display, subjects were asked to move a joystick in synchrony with the back and forth rotations of one part of the image while ignoring the other. Eye torsion was recorded with the scleral search coil technique, sampled at 500 Hz. All four subjects showed roughly 50% stronger torsion responses to the attended compared to unattended segments. Latency varied from 100 to 150 msec across subjects and was unchanged by attention. These findings suggest that attention can influence eye movement responses that are not typically under voluntary control.
Seismic behavior analysis of piled drums
International Nuclear Information System (INIS)
Aoki, H.; Kosaka, T.; Mizushina, T.; Shimizu, M.; Uji, S.; Tsuchiya, H.
1987-01-01
In general, low level radioactive waste is packed in drums and stored in a warehouse being piled vertically, or laid horizontally. To observe the behavior of piled drums during an earthquake, an experimental study was reported. The experimental study is limited by the vibrating platform capacity. To carry out these tests up to the supporting limit is not recommended, in view of the vibrating platform curing as well as the operators' security. It is very useful to develop the analytical method for simulating the behavior of the drums. In this report, a computer program of piled drum's dynamic motion is shown, and the analytical result is referred to the experimental result. From the result of experiment on piled drums, the sliding effect has been found to be very important for the stability of drum, and the rocking motion observed, showing a little acceleration is less than the static estimated value. Behavior of piled drums is a complex phenomena comprising of sliding, rocking and jumping
Resistance of i-beams in warping torsion with account for the development of plasticdeformations
Directory of Open Access Journals (Sweden)
Tusnin Aleksandr Romanovich
2014-01-01
Full Text Available Torsion of thin-walled open-section beams due to restrained warping displacements of cross-section is causing additional stresses, which make a significant contribution to the total stress. Due to plastic deformation there are certain reserves of bearing capacity, identification of which is of significant practical interest. The existing normative documents for the design of steel structures in Russia do not include design factor taking into account the development of plastic deformation during warping torsion. The analysis of thin-walled open-section members with plastic deformation will more accurately determine their load-bearing capacity and requires further research. Reserves of the beams bearing capacity due to the development of plastic deformations are revealed when beams are influenced by bending, as well as tension and compression. The existing methodology of determining these reserves and the plastic shape factor in bending was reviewed. This has allowed understanding how it was possible to solve this problem for warping torsion members and outline possible ways of theoretical studies of the bearing capacity in warping torsion. The authors used theoretical approach in determining this factor for the symmetric I-section beam under the action of bimoment and gave recommendations for the design of torsion members including improved value of plastic shape factor.
Lateral-Torsional Buckling Instability Caused by Individuals Walking on Wood Composite I-Joists
Villasenor Aguilar, Jose Maria
Recent research has shown that a significant number of the falls from elevation occur when laborers are working on unfinished structures. Workers walking on wood I-joists on roofs and floors are prone to fall hazards. Wood I-joists have been replacing dimension lumber for many floor systems and a substantial number of roof systems in light-frame construction. Wood I-joists are designed to resist axial stresses on the flanges and shear stresses on the web while minimizing material used. However, wood I-joists have poor resistance to applied lateral and torsional loads and are susceptible to lateral-torsional buckling instability. Workers walking on unbraced or partially braced wood I-joists can induce axial and lateral forces as well as twist. Experimental testing demonstrated that workers cause lateral-torsional buckling instability in wood I-joists. However, no research was found related to the lateral-torsional buckling instability induced by individuals walking on the wood I-joists. Furthermore, no research was found considering the effects of the supported end conditions and partial bracing in the lateral-torsional buckling instability of wood I-joists. The goal of this research was to derive mathematical models to predict the dynamic lateral-torsional buckling instability of wood composite I-joists loaded by individuals walking considering different supported end conditions and bracing system configurations. The dynamic lateral-torsional buckling instability was analyzed by linearly combining the static lateral-torsional buckling instability with the lateral bending motion of the wood Ijoists. Mathematical models were derived to calculate the static critical loads for the simply supported end condition and four wood I-joist hanger supported end conditions. Additionally, mathematical models were derived to calculate the dynamic maximum lateral displacements and positions of the individual walking on the wood Ijoists for the same five different supported end
Torsional oscillations of strange stars
Directory of Open Access Journals (Sweden)
Mannarelli Massimo
2014-01-01
Full Text Available Strange stars are one of the hypothetical compact stellar objects that can be formed after a supernova explosion. The existence of these objects relies on the absolute stability of strange collapsed quark matter with respect to standard nuclear matter. We discuss simple models of strange stars with a bare quark matter surface, thus standard nuclear matter is completely absent. In these models an electric dipole layer a few hundreds Fermi thick should exist close to the star surface. Studying the torsional oscillations of the electrically charged layer we estimate the emitted power, finding that it is of the order of 1045 erg/s, meaning that these objects would be among the brightest compact sources in the heavens. The associated relaxation times are very uncertain, with values ranging between microseconds and minutes, depending on the crust thickness. Although part of the radiated power should be absorbed by the electrosphere surrounding the strange star, a sizable fraction of photons should escape and be detectable.
Flexural-Torsional Flutter and Buckling of Braced Foil Beams under a Follower Force
Directory of Open Access Journals (Sweden)
Manuel Ferretti
2017-01-01
Full Text Available The flutter and buckling behavior of a cantilever foil beam, loaded at the tip by a follower force, are addressed in this paper. The beam is internally and externally damped and braced at the tip by a linear spring-damper device, which is located in an eccentric position with respect to beam axis, thus coupling the flexural and torsional behaviors. An exact linear stability analysis is carried out, and the linear stability diagram of the trivial rectilinear configuration is built up in the space of the follower load and spring’s stiffness parameters. The effects of the flexural-torsional coupling, as well as of the damping, on the flutter and buckling critical loads are discussed.
The Strength of Thin-wall Cylinders of D Cross Section in Combined Pure Bending and Torsion
Sherwood, A W
1943-01-01
The results of tests of 56 cylinders of D cross section conducted in the Aeronautical Laboratory of the University of Maryland are presented in this report. These cylinders were subjected to pure bending and torsional moments of varying proportions to give the strength under combined loading conditions. The average buckling stress of these cylinders has been related to that of circumscribing circular cylinders for conditions of pure torsion and pure bending and the equation of the interaction curve has been determined for conditions of combined loading.
Radiation Protection in the Experimental Pile Marius
International Nuclear Information System (INIS)
Cohendy, G.
1962-01-01
Measurements made around the experimental pile 'Marius' made it possible to determine the valid characteristics of the slabs designed to improve the biological protection by covering the charge and discharge pits. These measurements also made it possible to evaluate the risks occurring when the pile is operating at various Powers and to make a reasonable estimate of the value of the ratio of the total danger due to neutrons (thermal and fast) and γ radiation and to the danger due only to the γ radiation. A knowledge of this ratio makes it possible to make satisfactory evaluations with a single apparatus which is really portable. (author) [fr
Directory of Open Access Journals (Sweden)
Jingwei Cai
2016-01-01
Full Text Available For large-diameter, cast-in-place concrete piles, the end bearing capacity of a single pile is affected by discontinuous surfaces that exist in natural rock masses when the bearing layer of the pile end is located in the rock layer. In order to study the influence of the jointed dip angle on the bearing characteristics of the pile end, the discrete element models are adopted to simulate the mechanical characteristics of the jointed rock masses, and the model tests of the failure mode of the jointed rock masses were also designed. The results of the numerical calculations and modeling tests show that the joints, which have a filtering effect on the internal stress of the bedrock located at the pile end, change the load transferring paths. And the failure mode of the jointed rock foundation also changes as jointed dip angle changes. The rock located at the pile end generally presents a wedge failure mode. In addition, the Q-S curves obtained by model tests show that the ultimate end bearing capacity of a single pile is influenced by the jointed dip angle. The above results provide an important theoretical basis for how to correctly calculate end resistance for a cast-in-place concrete pile.
Synthesis of concrete bridge piles prestressed with CFRP systems.
2017-06-01
The Texas Department of Transportation frequently constructs prestressed concrete piles for use in bridge : foundations. Such prestressed concrete piles are typically built with steel strands that are highly susceptible to : environmental degradation...
The effect of pile parameters on the factor of safety of piled-slopes using 3D numerical analysis
Directory of Open Access Journals (Sweden)
Ahmed Abdelaziz
2017-12-01
Full Text Available Slope stability can be achieved using different methods. Piles are commonly used to stabilize slopes or to improve slope stability. Stabilized slopes with piles are numerically studied in the current paper. A 3 dimensional (3D finite element study is carried out to investigate the effect of different parameters on the stability of slopes stabilized with piles. A 3D finite element model was developed using the finite element program PLAXIS. The 3D model was verified using experimental data from the literature for a stabilized silty sand slope in a large-scale physical model. A parametric study was undertaken to study the effect of pile position, pile inclination, pile length and pile diameter on the factor of safety of the piled-slopes. The findings of the research were compared to other findings from the literature. The results show that using the 3D aspect gives more insight into the complicated slope stability problem. The study determines the optimum location of the pile and its optimum inclination to achieve the maximum stability. It shows that after a certain length of the pile, increasing the pile length becomes unnecessary and that the diameter of the pile has a relatively minor effect on the factor of safety of piled-slopes.
Torsional Split Hopkinson Bar Optimization
2012-04-10
cemented carbides , cast carbides , coated carbides , and coated high-speed steels, ranked by the cutting speed used to machine a unit volume of material...determine the load and deformation history of the specimen to obtain various mechanical properties of the material such as shear stress and strain. 15...simplified version of the process has as its objective to determine the load and deformation history of the specimen to obtain various mechanical
Charge Pricing Optimization Model for Private Charging Piles in Beijing
Directory of Open Access Journals (Sweden)
Xingping Zhang
2017-11-01
Full Text Available This paper develops a charge pricing model for private charging piles (PCPs by considering the environmental and economic effects of private electric vehicle (PEV charging energy sources and the impact of PCP charging load on the total load. This model simulates users’ responses to different combinations of peak-valley prices based on the charging power of PCPs and user charging transfer rate. According to the regional power structure, it calculates the real-time coal consumption, carbon dioxide emissions reduction, and power generation costs of PEVs on the power generation side. The empirical results demonstrate that the proposed peak-valley time-of-use charging price can not only minimize the peak-valley difference of the total load but also improve the environmental effects of PEVs and the economic income of the power system. The sensitivity analysis shows that the load-shifting effect of PCPs will be more obvious when magnifying the number of PEVs by using the proposed charging price. The case study indicates that the proposed peak, average, and valley price in Beijing should be 1.8, 1, and 0.4 yuan/kWh, which can promote the large-scale adoption of PEVs.
The Tensile Capacity Of Bored Piles In Frictional Soils
DEFF Research Database (Denmark)
Krabbenhøft, Sven; Andersen, Allan; Damkilde, Lars
2008-01-01
Three series of 10 piles each were installed in two different locations. The length of the piles varied from 2 to 6 m and the diameters were 14 and 25 cm. The piles were constructed above the groundwater table using continuous flight augers and the concrete was placed by gravity free fall. The pi...
Construction of Steel Pipe Sheet Piles with Newly Developed Joint ...
African Journals Online (AJOL)
H-joint in steel pipe sheet piles (SPSP) is introduced and developed, the joint is made by welding a cylindrical steel pile on either side of an H steel section, welding is continuous along their lengths therefore it is completely waterproof with high strength; the two connected piles are installed simultaneously hence short ...
Torsion profiling of proteins using magnetic particles.
van Reenen, A; Gutiérrez-Mejía, F; van Ĳzendoorn, L J; Prins, M W J
2013-03-05
We report a method to profile the torsional spring properties of proteins as a function of the angle of rotation. The torque is applied by superparamagnetic particles and has been calibrated while taking account of the magnetization dynamics of the particles. We record and compare the torsional profiles of single Protein G-Immunoglobulin G (IgG) and IgG-IgG complexes, sandwiched between a substrate and a superparamagnetic particle, for torques in the range between 0.5 × 10(3) and 5 × 10(3) pN·nm. Both molecular systems show torsional stiffening for increasing rotation angle, but the elastic and inelastic torsion stiffnesses are remarkably different. We interpret the results in terms of the structural properties of the molecules. The torsion profiling technique opens new dimensions for research on biomolecular characterization and for research on bio-nanomechanical structure-function relationships. Copyright © 2013 Biophysical Society. Published by Elsevier Inc. All rights reserved.
On the Modelling of Pile Installation
Dijkstra, J.
2009-01-01
This thesis introduces two different types of physical model tests to investigate the stress and density change in the soil during installation of a jacked pile as well as two numerical modelling approaches to model the same process in a finite element code capable of large deformations.
Underwater noise generated by offshore pile driving
Tsouvalas, A.
2015-01-01
Anthropogenic noise emission in the marine environment has always been an environmental issue of serious concern. In particular, the noise generated during the installation of foundation piles is considered to be one of the most significant sources of underwater noise pollution. This is mainly
Application Study of Self-balanced Testing Method on Big Diameter Rock-socketed Piles
Directory of Open Access Journals (Sweden)
Qing-biao WANG
2013-07-01
Full Text Available Through the technological test of self-balanced testing method on big diameter rock-socketed piles of broadcasting centre building of Tai’an, this paper studies and analyzes the links of the balance position selection, the load cell production and installation, displacement sensor selection and installation, loading steps, stability conditions and determination of the bearing capacity in the process of self-balanced testing. And this paper summarizes key technology and engineering experience of self-balanced testing method of big diameter rock-socketed piles and, meanwhile, it also analyzes the difficult technical problems needed to be resolved urgently at present. Conclusion of the study has important significance to the popularization and application of self-balanced testing method and the similar projects.
Directory of Open Access Journals (Sweden)
Ala Nasir Al-Jorany
2016-06-01
Full Text Available Soil movement resulting due unsupported excavation nearby axially loaded piles imposes significant structural troubles on geotechnical engineers especially for piles that are not designed to account for loss of lateral confinement. In this study the field excavation works of 7.0 m deep open tunnel was continuously followed up by the authors. The work is related to the project of developing the Army canal in the east of Baghdad city in Iraq. A number of selected points around the field excavation are installed on the ground surface at different horizontal distance. The elevation and coordinates of points are recorded during 23 days with excavation progress period. The field excavation process was numerically simulated by using the finite element package PLAXIS 3D foundation. The obtained analysis results regarding the displacements of the selected points are compared with the field observation for verification purpose. Moreover, finite element analysis of axially loaded piles that are presumed to be existed at the locations of the observation points is carried out to study the effect of excavation on full scale piles behaviors. The field observation monitored an upward movement and positive lateral ground movement for shallow excavation depth. Later on and as the excavation process went deeper, a downward movement and negative lateral ground movement are noticed. The analyses results are in general well agreed with the monitored values of soil displacements at the selected points. It is found also that there are obvious effects of the nearby excavation on the presumed piles in terms of displacements and bending moments.
Ocular torsional movements in normal humans.
Kushner, B J; Kraft, S
1983-06-01
We conducted three studies of compensatory ocular torsional movements in normal human subjects, using changes in the axis of astigmatism, afterimages, and direct observation with cinematography. Measurements of changes in the axis of astigmatism and the subjects' subjective perception of afterimages with a superimposed Maddox rod showed a partial compensatory intorsion on head tilt to the ipsilateral side and extorsion on head tilt to the contralateral side. Cinematography demonstrated that the eye lags behind the head in a slow rolling movement as the head is tilted. Periodic rotary movements in the direction of the head tilt partially correct the lag and result in a partial compensatory torsion. A fourth experiment excluded false torsion as an artifact in these studies.
Torsional rigidity of submanifolds with controlled geometry
DEFF Research Database (Denmark)
Hurtado, Ana; Markvorsen, Steen; Palmer, Vicente
2009-01-01
We prove explicit upper and lower bounds for the torsional rigidity of extrinsic domains of submanifolds ^m$ with controlled radial mean curvature in ambient Riemannian manifolds ^n$ with a pole $ and with sectional curvatures bounded from above and from below, respectively. These bounds are given...... in terms of the torsional rigidities of corresponding Schwarz symmetrizations of the domains in warped product model spaces. Our main results are obtained using methods from previously established isoperimetric inequalities, as found in e.g. [MP4] and [MP5]. As in [MP4] we also characterize the geometry...... of those situations in which the bounds for the torsional rigidity are actually attained and study the behavior at infinity of the so-called geometric average of the mean exit time for Brownian motion....
Surface crack growth in cylindrical hollow specimen subject to tension and torsion
Directory of Open Access Journals (Sweden)
V. Shlyannikov
2015-07-01
Full Text Available The subject for studies is an aluminium cylindrical hollow specimen with external axial and part circumferential semi-elliptical surface crack undergoing fatigue loads. Both the optical microscope measurements and the crack opening displacement (COD method are used to monitor and calculate both crack depth and crack length during the tests. The variation of crack growth behaviour is studied under cyclic axial tension, pure torsion and combined tension+torsion fatigue loading. For the particular surface flaw geometries considered, the elastic and plastic in-plane and out-of-plane constraint parameters, as well as the governing parameter for stress fields in the form of In-integral and plastic stress intensity factor, are obtained as a function of the aspect ratio, dimensionless crack length and crack depth. The combined effect of tension and torsion loading and initial surface flaw orientation on the crack growth for two type of aluminium alloys is made explicit. The experimental and numerical results of the present study provided the opportunity to explore the suggestion that fatigue crack propagation may be governed more strongly by the plastic stress intensity factor rather than the magnitude of the elastic SIFs alone. One advantage of the plastic SIF is its sensitivity to combined loading due to accounting for the plastic properties of the material.
Multiaxial fatigue criterion based on parameters from torsion and axial S-N curve
Directory of Open Access Journals (Sweden)
M. Margetin
2016-07-01
Full Text Available Multiaxial high cycle fatigue is a topic that concerns nearly all industrial domains. In recent years, a great deal of recommendations how to address problems with multiaxial fatigue life time estimation have been made and a huge progress in the field has been achieved. Until now, however, no universal criterion for multiaxial fatigue has been proposed. Addressing this situation, this paper offers a design of a new multiaxial criterion for high cycle fatigue. This criterion is based on critical plane search. Damage parameter consists of a combination of normal and shear stresses on a critical plane (which is a plane with maximal shear stress amplitude. Material parameters used in proposed criterion are obtained from torsion and axial S-N curves. Proposed criterion correctly calculates life time for boundary loading condition (pure torsion and pure axial loading. Application of proposed model is demonstrated on biaxial loading and the results are verified with testing program using specimens made from S355 steel. Fatigue material parameters for proposed criterion and multiple sets of data for different combination of axial and torsional loading have been obtained during the experiment.
Steffen, Heimo; Straumann, Dominik S; Walker, Mark F; Miller, Neil R; Guyton, David L; Repka, Michael X; Zee, David S
2008-05-01
The purpose was to assess intra- and post-saccadic torsion in superior oblique palsy (SOP) patients and the effect of surgery on torsion. Eleven patients with a presumed congenital SOP and five with acquired SOP performed 10 degrees vertical saccades over a range of +/-20 degrees. Eye movements were recorded with dual search coils. Dynamic torsion was calculated by subtracting the expected change in torsion during the saccade (based upon static torsion before and after the saccade) from the maximum intrasaccadic torsion. Eight healthy subjects were controls. We also examined the effects of surgery on dynamic torsion and the orientation of Listing's plane in patients with congenital SOP who were operated on either by weakening of the inferior oblique muscle on the affected eye (n=5), by recession of the inferior rectus muscle on the normal eye (n=4) or by both procedures (n=2). Postoperative recordings were obtained at least 1 month after surgery. Patients with congenital and acquired SOP showed an increased dynamic extorsion, primarily during downward saccades. Following a recession of the inferior oblique muscle in congenital SOP patients, half showed significant decreases in extorsion (up to 1.0 degrees) during downward saccades by the affected eye. Following surgery all showed a temporal rotation of Listing's plane (up to 15 degrees for primary position). Patients with a SOP show a characteristic pattern of dynamic torsion during vertical saccades differing from normals. Recession of the inferior oblique muscle leads to rotation of Listing's plane in all congenital SOP patients and causes large changes in dynamic torsion in a subgroup of them, perhaps reflecting the heterogeneity of congenital SOP.
DEFF Research Database (Denmark)
Alberdi Pagola, Maria; Madsen, Søren; Lund Jensen, Rasmus
2017-01-01
and shaft resistances; ii) the maximum upward/downward displacements. A one-year time span is considered under operational and extreme thermal boundary conditions. The results show that a typical geothermal utilization of the energy foundation does not generate significant structural implications...... on the geotechnical capacity of a single energy pile. However, ground thermal loads need to be considered in the design phase to account for potential extreme temperature changes, which could generate thermal stresses that equalize the mechanically generated ones....
Torsional fatigue model for limitorque type SMB/SB/SBD actuators for motor-operated valves
Energy Technology Data Exchange (ETDEWEB)
Somogyi, D.; Alvarez, P.D.; Kalsi, M.S. [Kalsi Engineering, Inc., Sugar Land, TX (United States)
1996-12-01
Kalsi Engineering, Inc. has recently developed a computer program to predict the torsional fatigue life of Limitorque Type SMB/SB/SBD actuators for motor-operated valves under given loading levels, including those that exceed the ratings. The development effort was an outgrowth of the {open_quote}Thrust Rating Increase{close_quote} test program. The fatigue model computes all pertinent stress components and their variations as a function of the loading ramp. The cumulative damage and fatigue life due to stress cycling is computed by use of a modification of Miner`s rule. Model predictions were validated against actual cyclic loading test results.
Torsional fatigue model for limitorque type SMB/SB/SBD actuators for motor-operated valves
International Nuclear Information System (INIS)
Somogyi, D.; Alvarez, P.D.; Kalsi, M.S.
1996-01-01
Kalsi Engineering, Inc. has recently developed a computer program to predict the torsional fatigue life of Limitorque Type SMB/SB/SBD actuators for motor-operated valves under given loading levels, including those that exceed the ratings. The development effort was an outgrowth of the open-quote Thrust Rating Increase close-quote test program. The fatigue model computes all pertinent stress components and their variations as a function of the loading ramp. The cumulative damage and fatigue life due to stress cycling is computed by use of a modification of Miner's rule. Model predictions were validated against actual cyclic loading test results
On the geometrization of electromagnetism by torsion
International Nuclear Information System (INIS)
Fonseca Neto, J.B. da.
1984-01-01
The possibility of electromagnetism geometrization using an four dimension Cartan geometry is investigated. The Lagrangian density which presents dual invariance for dyons electrodynamics formulated in term of two potentials is constructed. This theory by association of two potentials with track and with torsion pseudo-track and of the field with torsion covariant divergent is described. The minimum coupling of particle gravitational field of scalar and spinorial fields with dyon geometry theory by the minimum coupling of these fields with Cartan geometry was obtained. (author)
The torsion of the multicell sections
Directory of Open Access Journals (Sweden)
Marcel STERE
2010-09-01
Full Text Available The paper is focused on the stress analysis of thin-walled multicell sections subjected to pure torsion. The shear flow and stiffness characteristics of the cross section for torsion are given. Example: aircraft wing section. The theory for thin-walled closed sections used in this paper was developed by Bredt [3]. The shear flows obtained are used in the design of skins and interior webs, ribs and fasteners at skin splices, skin web junctions and the joints where the ribs meet the skin or webs.
Disseminated peritoneal leiomyomatosis mimicking ovarian torsion
Directory of Open Access Journals (Sweden)
Chau-Yang Tyan
2015-01-01
Full Text Available The presentation of disseminated peritoneal leiomyomatosis (DPL can be misleading. Herein, we present the case of a 42-year-old nulliparous female who had previously undergone a total hysterectomy and presented with an acute abdomen. A presumptive diagnosis of ovarian torsion was made based on the clinical findings and an ultrasonographic examination. A diagnostic laparoscopy was performed immediately. DPL was subsequently diagnosed based on an intra-operative frozen section during surgical exploration and the final histopathologic examination. This case illustrates an atypical presentation of DPL mimicking ovarian torsion.
Torsional Performance of Wind Turbine Blades
DEFF Research Database (Denmark)
Branner, Kim; Berring, Peter; Berggreen, Christian
2007-01-01
The present work investigates how well different finite element modeling techniques can predict bending and torsion behavior of a wind turbine blade. Two shell models are investigated. One model has element offsets and the other has the elements at the mid-thickness surfaces of the model. The last...... two models investigated use a combination of shell and solid elements. The results from the numerical investigations are compared with measurements from testing of a section of a full-scale wind turbine blade. It is found that only the combined shell/solid models give reliable results in torsion. Both...
2015-05-01
The overall goal of this project is the experimental evaluation and design of unfilled and concrete-filled FRP composite piles for load-bearing in bridges. This report covers Task 7, Final Report - Thesis. : This final report covers Tasks 1, 2, 3, 5 ...
Directory of Open Access Journals (Sweden)
Suksun Horpibulsuk
2013-08-01
Full Text Available This paper presents the development of geotechnical maps in Nakhon Ratchasima municipality, Nakhon Ratchasima province, Thailand based on the boring logs and in situ test results collected from public and private sector sources. The standard penetration number, N was used to identify the soil type. The soil deposits in Nakhon Ratchasima municipality are divided into three layers: medium-to-stiff silty clay with N 50. The medium-to-stiff silty clay layer has a thickness varying from 1.8 to 7.5 metres and an average N value of 14 with a relatively low standard deviation of 1.08. The first hard silty clay layer has a thickness varying from 1.2 to 3.0 metres and an average N value of 42 with a standard deviation of 1.37. For a practical application in foundation engineering in which the pile tips of the bored piles are located in the second hard stratum with N > 50, eight pile tip zones with approximated load capacity are recommended for pile lengths of 3-10 metres.
Starting up a programme of atomic piles using compressed gas
International Nuclear Information System (INIS)
Horowitz, J.; Yvon, J.
1959-01-01
1) An examination of the intellectual and material resources which have directed the French programme towards: a) the natural uranium and plutonium system, b) the use of compressed gas as heat transfer fluid (primary fluid). 2) The parts played in exploring the field by the pile EL2 and G1, EL2 a natural uranium, heavy water and compressed gas pile, G1 a natural uranium, graphite and atmospheric air pile. 3) Development of the neutronics of graphite piles: physical study of G1. 4) The examination of certain problem posed by centres equipped with natural uranium, graphite and compressed carbon dioxide piles: structure, special materials, fluid circuits, maximum efficiency. Economic aspects. 5) Aids to progress: a) piles for testing materials and for tests on canned fuel elements, b) laboratory and calculation facilities. 6) Possible new orientations of compressed gas piles: a) raising of the pressure, b) enriched fuel, c) higher temperatures, d) use of heavy water. (author) [fr
Model tests on single piles in soft clay
Energy Technology Data Exchange (ETDEWEB)
Pan, J.L. [Durham Univ., Durham, (United Kingdom). School of Engineering; Goh, A.T.C.; Wong, K.S.; Teh, C.I. [Nanyang Technological Univ., (Singapore). Geotechnical Research Centre
2000-08-04
The behaviour of single stainless steel piles subjected to lateral soft clay soil movement was investigated in laboratory model tests in an effort to determine the ultimate soil pressure acting along the pile shaft. A custom designed apparatus was manufactured and calibrated for the test which measured the limiting soil pressures acting along the model pile shaft. The ultimate soil pressure was determined based on the maximum value of this measurement. The results show that the ultimate soil pressure for single passive piles was about 10 times the undrained shear strength, and the magnitude of the soil translation needed to fully mobilize the ultimate soil pressure on the single passive piles was about half the pile width. Further experimental study is needed to examine the effects of the pile end fixity, flexibility and shape and to confirm the effects of sample size and the disturbance due to soil sample preparation. 17 refs., 10 figs.
Torsion of the fallopian tube: progression of sonographic features.
Richard, H M; Parsons, R B; Broadman, K F; Shapiro, R S; Yeh, H C
1998-09-01
Isolated torsion of the fallopian tube is a rare gynecologic condition that is difficult to diagnose preoperatively. We present the sonographic and CT findings over a 48-hour period in a case of isolated torsion of the fallopian tube. The radiologic features of isolated torsion have been described previously; however, to our knowledge, the progressive findings have not been previously reported.
Testicular torsion: case report | Kuremu | East African Medical Journal
African Journals Online (AJOL)
This is a report of bilateral testicular torsion. The objective of the report is to highlight the serious implications of misdiagnosis of testicular torsion. Other than loss of the testis due to necrosis in unilateral torsion, immunological damage of the opposite testis occurs. Early, accurate diagnosis, and institution of the appropriate ...
Investigation method of torsional properties and damages of glass/epoxy composite pipes
Directory of Open Access Journals (Sweden)
Putić Slaviša S.
2006-01-01
Full Text Available Pipes made of composites glass fiber/epoxy resin are predominantly used in the chemical industry, construction, infrastructure and war technique. The pipes made for this purpose are in their use exposed to static and dynamic loading. Depending on the purpose, the pipes, especially those in complex structures, can be loaded by torsion. In that case, exceeding allowed tensions can cause damages such as cracking the fibers and matrix delamination. These damages can lead to the appearance of cracks on the pipes and in many cases to complete breakage of the pipe. Because of this, it is very important to evaluate composite pipes exposed to torsion and find out in which way the construction is weakened, what actually is the main goal of this paper.
Effect of web openings on the structural behavior of RC beams subjected to pure torsion
Directory of Open Access Journals (Sweden)
Abdo Taha
2017-01-01
Full Text Available In the construction of modern buildings, the presence of openings became a necessity nowadays in order to accommodate the many pipes and ducts required for the different services. On the other hand, the presence of these openings in RC beams affects their structural behavior. One important behavior that needs further study would be torsion. Currently, there are no guide lines available to analyze or design RC beams with web openings under pure torsion. Thus, the main objective of this research is to investigate the behavior of simply supported RC beams with openings subjected to pure torsion. In the first part of this paper, an experimental study is conducted on seven beams subjected to pure torsion loading in order to investigate the effect of the number of openings, the spacing between stirrups, and beam depth. All beams have a constant clear span length of 1800 mm and a constant beam width of 150 mm. The beams have varying opening number and stirrups arrangement as well as varying beam depth in order to investigate the effect of these parameters on the behavior of the beams. Systematic measurements such as the cracking torque, the ultimate torque, the angle of rotation of the beam at cracking, and the angle of rotation of the beam at the ultimate load are conducted for further understanding of the beam behavior under torsion. In the second part of the paper, the experimental results are compared with the numerical results obtained using the non-linear finite element analysis program, ANSYS. Good agreement between the experimental and numerical results is found.
Saint-Venant torsion of non-homogeneous anisotropic bars
Directory of Open Access Journals (Sweden)
John T. Katsikadelis
2016-01-01
Full Text Available The BEM is applied to the solution of the torsion problem of non-homogeneous anisotropic non-circular prismatic bars. The problem is formulated in terms of the warping function. This formulation leads to a second order partial differential equation with variable coefficients, subjected to a generalized Neumann type boundary condition. The problem is solved using the Analog Equation Method (AEM. According to this method, the governing equation is replaced by a Poisson’s equation subjected to a fictitious source under the same boundary condition. The fictitious load is established using the Boundary Element Method (BEM after expanding it into a finite series of radial basis functions. The method has all the advantages of the pure BEM, since the discretization and integration are limited only on to the boundary. Numerical examples are presented which illustrate the efficiency and accuracy of the method.
Structural Loading of Cross Deck Connections for Trimaran Vessels
National Research Council Canada - National Science Library
Rhoads, Jason
2004-01-01
...: longitudinal bending, transverse bending, torsional bending, spreading and squeezing of hulls, inner and outer hull slam pressures, wet deck slam pressures, loading from ship's motions, and whipping of slender hulls...
Kwak, Sang-Won; Ha, Jung-Hong; Lee, WooCheol; Kim, Sung-Kyo; Kim, Hyeon-Cheol
2014-11-01
This study compared the mechanical properties of various instruments for canal exploration and glide-path preparations. The buckling resistance, bending stiffness, ultimate torsional strength, and fracture angle under torsional load were compared for C+ file (CP, Dentsply Maillefer), M access K-file (MA, Dentsply Maillefer), Mani K-file (MN, Mani), and NiTiFlex K-file (NT, Dentsply Maillefer). The files of ISO size #15 and a shaft length of 25 mm were selected. For measuring buckling resistance (n = 10), the files were loaded in the axial direction of the shaft, and the maximum load was measured during the files' deflection. The files (n = 10) were fixed at 3-mm from the tip and then bent 45° with respect to their long axis, while the bending force was recorded by a load cell. For measuring the torsional properties, the files (n = 10) were also fixed at 3-mm, and clockwise rotations (2-rpm) were applied to the files in a straight state. The torsional load and the distortion angle were recorded until the files succumbed to the torque. The CP was shown to require the highest load to buckle and bend the files, and the NT showed the least. While MA and MN showed similar buckling resistances, MN showed higher bending stiffness than MA. The NT had the lowest bending stiffness and ultimate torsional strength (p < 0.05). The tested instruments showed different mechanical properties depending on the evaluated parameters. CP and NT files were revealed to be the stiffest and the most flexible instruments, respectively.
Torsional Shear Device for Testing the Dynamic Properties of Recycled Material
Gabryś, Katarzyna; Sas, Wojciech; Soból, Emil; Głuchowski, Andrzej
2016-12-01
From the viewpoint of environmental preservation and effective utilization of resources, it is beneficial and necessary to reuse wastes, for example, concrete, as the recycled aggregates for new materials. In this work, the dynamic behavior of such aggregates under low frequency torsional loading is studied. Results show that the properties of such artificial soils match with those reported in the literature for specific natural soils.
Torsional Shear Device for Testing the Dynamic Properties of Recycled Material
Directory of Open Access Journals (Sweden)
Gabryś Katarzyna
2016-12-01
Full Text Available From the viewpoint of environmental preservation and effective utilization of resources, it is beneficial and necessary to reuse wastes, for example, concrete, as the recycled aggregates for new materials. In this work, the dynamic behavior of such aggregates under low frequency torsional loading is studied. Results show that the properties of such artificial soils match with those reported in the literature for specific natural soils.
Lateral-torsional buckling of laminated structural glass beams. Experimental study
Pešek, Ondřej; Melcher, Jindřich
2017-01-01
This paper deals with experimental research of stability behaviour of laminated structural glass beams. The purpose of the research is the evaluation of lateral-torsional buckling resistance and actual behaviour of the beams due to absence of standards for design of glass load-bearing structures. The experimental research follows the previous one focusing on measuring of initial geometrical imperfections of glass members and experimental evaluation of flexural buckling resistance of structura...
Plant-based torsional actuator with memory
Nayomi Plaza; Samuel L. Zelinka; Don S. Stone; Joseph E. Jakes
2013-01-01
A bundle of a few loblolly pine (Pinus taeda) cells are moisture-activated torsional actuators that twist multiple revolutions per cm length in direct proportion to moisture content. The bundles generate 10 N m kg1 specific torque during both twisting and untwisting, which is higher than an electric motor. Additionally, the bundles exhibit a moisture-...
Torsional Performance of Wind Turbine Blades
DEFF Research Database (Denmark)
Branner, Kim; Berring, Peter; Berggreen, Christian
2007-01-01
The present work investigates how well different finite element modeling techniques can predict bending and torsion behavior of a wind turbine blade. Two shell models are investigated. One model has element offsets and the other has the elements at the mid-thickness surfaces of the model. The las...
Torsion of the gallbladder: a case report
Directory of Open Access Journals (Sweden)
Ijaz Samia
2008-07-01
Full Text Available Abstract Introduction Torsion of the gallbladder is a rare condition that most commonly affects the elderly. Pre-operative diagnosis is the exception rather than the rule. Any delay in treatment can be fatal as the gallbladder may rupture, leading to biliary peritonitis. Case presentation We present the case of an 80-year-old woman who was admitted with right upper quadrant pain initially thought to be secondary to acute cholecystitis. Subsequent ultrasound and computed tomography scans of the abdomen revealed signs suggestive of acute cholecystitis but neither modality detected any gallstones. As the patient's symptoms failed to resolve on conservative management, she was taken to theatre for an open cholecystectomy. Intra-operatively, the gallbladder had undergone complete torsion and appeared gangrenous. A routine cholecystectomy followed and she recovered from the operation without incident. Conclusion It is rare to diagnose torsion of the gallbladder pre-operatively despite advances in diagnostic imaging. However, this differential diagnosis should be borne in mind particularly in the elderly patient, without proven gallstones, who fails to improve on conservative management. An emergency cholecystectomy is indicated in the event of diagnosing torsion of the gallbladder to avert the potentially lethal sequelae of biliary peritonitis.
Management and Outcome of Testicular Torsion
African Journals Online (AJOL)
multiruka1
MSH, AFS, CGH: Research International East. Africa Limited. Coast Province General Hospital report 2015. 8. Lee SM, Huh JS, BaekM, et al. A Nationwide. Epidemiological Study of Testicular Torsion in. Korea. J Korean Med Sci. 2014; 29(12): 1684–1687. 9. Cattolica EV, Karol JB, Rankin KN, et al. High. Testicular Salvage ...
Right paratesticular abscess mimicking neonatal testicular torsion ...
African Journals Online (AJOL)
U.O. Ezomike
Right paratesticular abscess mimicking neonatal testicular torsion and caused by Proteus mirabilis. U.O. Ezomikea,∗. , M.A. Ituena, S.C. Ekpemoa, S.O. Ekenzeb a Department of Surgery, Federal Medical Centre Umuahia, Abia State, Nigeria b Sub-Department of Pediatric Surgery, University of Nigeria Teaching Hospital, ...
Conformal deformation of Riemann space and torsion
International Nuclear Information System (INIS)
Pyzh, V.M.
1981-01-01
Method for investigating conformal deformations of Riemann spaces using torsion tensor, which permits to reduce the second ' order equations for Killing vectors to the system of the first order equations, is presented. The method is illustrated using conformal deformations of dimer sphere as an example. A possibility of its use when studying more complex deformations is discussed [ru
Torsion of the gallbladder: a case report.
Ijaz, Samia; Sritharan, Kaji; Russell, Neil; Dar, Manzoor; Bhatti, Tahir; Ormiston, Michael
2008-07-24
Torsion of the gallbladder is a rare condition that most commonly affects the elderly. Pre-operative diagnosis is the exception rather than the rule. Any delay in treatment can be fatal as the gallbladder may rupture, leading to biliary peritonitis. We present the case of an 80-year-old woman who was admitted with right upper quadrant pain initially thought to be secondary to acute cholecystitis. Subsequent ultrasound and computed tomography scans of the abdomen revealed signs suggestive of acute cholecystitis but neither modality detected any gallstones. As the patient's symptoms failed to resolve on conservative management, she was taken to theatre for an open cholecystectomy. Intra-operatively, the gallbladder had undergone complete torsion and appeared gangrenous. A routine cholecystectomy followed and she recovered from the operation without incident. It is rare to diagnose torsion of the gallbladder pre-operatively despite advances in diagnostic imaging. However, this differential diagnosis should be borne in mind particularly in the elderly patient, without proven gallstones, who fails to improve on conservative management. An emergency cholecystectomy is indicated in the event of diagnosing torsion of the gallbladder to avert the potentially lethal sequelae of biliary peritonitis.
Pseudotopological quasilocal energy of torsion gravity
Ko, Sheng-Lan; Lin, Feng-Li; Ning, Bo
2017-08-01
Torsion gravity is a natural extension to Einstein gravity in the presence of fermion matter sources. In this paper we adopt Wald's covariant method of calculating the Noether charge to construct the quasilocal energy of the Einstein-Cartan-fermion system, and find that its explicit expression is formally independent of the coupling constant between the torsion and axial current. This seemingly topological nature is unexpected and is reminiscent of the quantum Hall effect and topological insulators. However, a coupling dependence does arise when evaluating it on shell, and thus the situation is pseudotopological. Based on the expression for the quasilocal energy, we evaluate it for a particular solution on the entanglement wedge and find agreement with the holographic relative entropy obtained before. This shows the equivalence of these two quantities in the Einstein-Cartan-fermion system. Moreover, the quasilocal energy in this case is not always positive definite, and thus it provides an example of a swampland in torsion gravity. Based on the covariant Noether charge, we also derive the nonzero fermion effect on the Komar angular momentum. The implications of our results for future tests of torsion gravity in gravitational-wave astronomy are also discussed.
The spectrum of axisymmetric torsional Alfven waves
International Nuclear Information System (INIS)
Sy, W.N.
1977-03-01
The spectrum of axisymmetric torsional Alfven waves propagating in a cylindrical, non-uniform, resistive plasma waveguide has been analysed by a method of singular perturbations. A simple condition has been derived which predicts whether the spectrum is continuous or discrete under given physical conditions. Application of this result to resolve an apparent discrepancy in experimental observations is briefly discussed. (Author)
Gosiewski, J D; Holsgrove, T P; Gill, H S
2017-05-01
Fractures of the proximal femur are a common clinical problem, and a number of orthopaedic devices are available for the treatment of such fractures. The objective of this study was to assess the rotational stability, a common failure predictor, of three different rotational control design philosophies: a screw, a helical blade and a deployable crucifix. Devices were compared in terms of the mechanical work (W) required to rotate the implant by 6° in a bone substitute material. The substitute material used was Sawbones polyurethane foam of three different densities (0.08 g/cm 3 , 0.16 g/cm 3 and 0.24 g/cm 3 ). Each torsion test comprised a steady ramp of 1°/minute up to an angular displacement of 10°. The deployable crucifix design (X-Bolt), was more torsionally stable, compared to both the dynamic hip screw (DHS, p = 0.008) and helical blade (DHS Blade, p= 0.008) designs in bone substitute material representative of osteoporotic bone (0.16 g/cm 3 polyurethane foam). In 0.08 g/cm 3 density substrate, the crucifix design (X-Bolt) had a higher resistance to torsion than the screw (DHS, p = 0.008). There were no significant differences (p = 0.101) between the implants in 0.24 g/cm 3 density bone substitute. Our findings indicate that the clinical standard proximal fracture fixator design, the screw (DHS), was the least effective at resisting torsional load, and a novel crucifix design (X-Bolt), was the most effective design in resisting torsional load in bone substitute material with density representative of osteoporotic bone. At other densities the torsional stability was also higher for the X-Bolt, although not consistently significant by statistical analysis. Cite this article : J. D. Gosiewski, T. P. Holsgrove, H. S. Gill. The efficacy of rotational control designs in promoting torsional stability of hip fracture fixation. Bone Joint Res 2017;6:270-276. DOI: 10.1302/2046-3758.65.BJR-2017-0287.R1. © 2017 Gosiewski et al.
Including Torsional Anharmonicity in Canonical and Microcanonical Reaction Path Calculations.
Zheng, Jingjing; Truhlar, Donald G
2013-07-09
We reformulate multistructural variational transition state theory by removing the approximation of calculating torsional anharmonicity only at stationary points. The multistructural method with torsional anharmonicity is applied to calculate the reaction-path free energy of the hydrogen abstraction from the carbon-1 position in isobutanol by OH radical. The torsional potential anharmonicity along the reaction path is taken into account by a coupled torsional potential. The calculations show that it can be critical to include torsional anharmonicity in searching for canonical and microcanonical variational transition states. The harmonic-oscillator approximation fails to yield reasonable free energy curves along the reaction path.
[Conservative surgery of ovarian torsion in pediatrics].
Abad, P; Rigol, S; Ezzedine, H; Durán, C; Ortega, D; Martí, M; Pinyot, J
2003-10-01
The authors describe the case of two girls diagnosed of ovarian torsion secondary to a cyst. They were operated on by conservative ovarian therapy regardless the time of evolution and ovary macroscopical aspect. These 2 patients were 9 and 13 years old, with abdominal colic pain of 48 and 36 hours of evolution. The diagnosis by doppler sonography was ovarian torsion, with a 4 cms cyst in the right ovary in the first case and a 5 cms cyst in the left ovary in the second patient. Both patients were operated on. After untwisting the ovary, we instille warm saline solution to this ovary and, after waiting for 10 minutes, we resect the ovarian cyst and it recuperates partial and heterogeneous its pink colour. We advise to the family about the possibility of surgical reintervention if the ovary is not viable. After 10 and 12 days of surgical intervention, the Doppler sonography has confirmed the existence of ovary flow and the symmetry of affected ovary in comparation to the opposite on. At the present, both patients are asymptomatic, with exhaustive ultrasound controls. Ovarian torsion is the most frequent complication of ovarian tumours of pediatrics (3-16%) and this is a real emergency in gynecology. Traditionally, it has been recommended the exeresis of ovarian torsion. Regardless the blue aspect of isquemic ovary affected by torsion and the time of evolution, in our experience when there is a minimal possibility of ovarian viability, it is possible to follow a conservative therapy because the macroscopical aspect of the ovary is not necessarily related with the following evolution of the case.
Horizontal vibrations of piles in a centrifuge
International Nuclear Information System (INIS)
Bourdin, B.
1987-01-01
The aim of the thesis is the study of soil dynamics for important structures like nuclear power plants, offshore platforms, dams etc. Experimental results of horizontal vibrations on a pile partially anchored in a soil scale model put into a centrifuge are presented. Mechanical similitude conditions from equilibrium equations or rheologic laws are described. After a description of testing equipment (centrifuge, electrodynamic excitator) experimental results are interpreted with a model. Non-linearities on frequency response curves are characterized [fr
Integrity Testing of Pile Cover Using Distributed Fibre Optic Sensing
Directory of Open Access Journals (Sweden)
Yi Rui
2017-12-01
Full Text Available The integrity of cast-in-place foundation piles is a major concern in geotechnical engineering. In this study, distributed fibre optic sensing (DFOS cables, embedded in a pile during concreting, are used to measure the changes in concrete curing temperature profile to infer concrete cover thickness through modelling of heat transfer processes within the concrete and adjacent ground. A field trial was conducted at a high-rise building construction site in London during the construction of a 51 m long test pile. DFOS cables were attached to the reinforcement cage of the pile at four different axial directions to obtain distributed temperature change data along the pile. The monitoring data shows a clear development of concrete hydration temperature with time and the pattern of the change varies due to small changes in concrete cover. A one-dimensional axisymmetric heat transfer finite element (FE model is used to estimate the pile geometry with depth by back analysing the DFOS data. The results show that the estimated pile diameter varies with depth in the range between 1.40 and 1.56 m for this instrumented pile. This average pile diameter profile compares well to that obtained with the standard Thermal Integrity Profiling (TIP method. A parametric study is conducted to examine the sensitivity of concrete and soil thermal properties on estimating the pile geometry.
Review of vibration effect during piling installation to adjacent structure
Rahman, Nurul Aishah Abd; Musir, Adhilla Ainun; Dahalan, Nurol Huda; Ghani, Abdul Naser Abdul; Khalil, Muhamad Kasimi Abd
2017-12-01
Basically, many major structures across the world such as towers, high rise building, houses and bridges utilize pile as a support material. The use of pile is important to strengthen the structures. However, this has led to another problem to the nearest surrounding structures resulted from pile driving. As part of a construction work, unavoidable pile driving activity generates a vibration towards the surrounding structures if uncontrolled may cause damage to the adjacent structure. As the current construction works are frequently located in urban areas where the distance between the nearest building structures is not far, vibration may cause damage to nearby structures. Knowing which part of the building that is mostly affected by various vibration patterns from the impact of pile driving is crucial. Thus, it is very important to predict the impact of vibration during piling installation work. This paper reviews the vibrations generated by piling activity toward surrounding structures in terms sources of vibration, impact of piling installation, pile-soil interaction, and factors affecting the vibration impact of building as well as to study the parameters involved in vibration generation during piling works.
Integrity Testing of Pile Cover Using Distributed Fibre Optic Sensing
Rui, Yi; Kechavarzi, Cedric; O’Leary, Frank; Barker, Chris; Nicholson, Duncan; Soga, Kenichi
2017-01-01
The integrity of cast-in-place foundation piles is a major concern in geotechnical engineering. In this study, distributed fibre optic sensing (DFOS) cables, embedded in a pile during concreting, are used to measure the changes in concrete curing temperature profile to infer concrete cover thickness through modelling of heat transfer processes within the concrete and adjacent ground. A field trial was conducted at a high-rise building construction site in London during the construction of a 51 m long test pile. DFOS cables were attached to the reinforcement cage of the pile at four different axial directions to obtain distributed temperature change data along the pile. The monitoring data shows a clear development of concrete hydration temperature with time and the pattern of the change varies due to small changes in concrete cover. A one-dimensional axisymmetric heat transfer finite element (FE) model is used to estimate the pile geometry with depth by back analysing the DFOS data. The results show that the estimated pile diameter varies with depth in the range between 1.40 and 1.56 m for this instrumented pile. This average pile diameter profile compares well to that obtained with the standard Thermal Integrity Profiling (TIP) method. A parametric study is conducted to examine the sensitivity of concrete and soil thermal properties on estimating the pile geometry. PMID:29257094
Geomorphic reclmation of a coal refuse pile
Hopkinson, L. C.; Quaranta, J.
2017-12-01
Geomorphic reclamation is a technique that may offer opportunities to improve mine reclamation in Central Appalachia. The design approach is based on constructing a steady-state, mature landform condition and takes into account the long-term climatic conditions, soil types, terrain grade, and vegetation. Geomorphic reclamation has been applied successfully in semi-arid regions but has not yet been applied in Central Appalachia. This work describes a demonstration study where geomorphic landforming techniques are being applied to a coarse coal refuse pile in southern West Virginia, USA. The reclamation design includes four geomorphic watersheds that radially drain runoff from the pile. Each watershed has one central draining channel and incorporates compound slope profiles similarly to naturally eroded slopes. Planar slopes were also included to maintain the impacted area. The intent is to alter the hydrology to decrease water quality treatment costs. The excavation cut and fill volumes are comparable to those of more conventional refuse pile reclamation designs. If proven successful then this technique can be part of a cost-effective solution to improve water quality at active and future refuse facilities, abandoned mine lands, bond forfeiture sites, landfills, and major earthmoving activities within the region.
FORECASTING PILE SETTLEMENT ON CLAYSTONE USING NUMERICAL AND ANALYTICAL METHODS
Directory of Open Access Journals (Sweden)
Ponomarev Andrey Budimirovich
2016-06-01
Full Text Available In the article the problem of designing pile foundations on claystones is reviewed. The purpose of this paper is comparative analysis of the analytical and numerical methods for forecasting the settlement of piles on claystones. The following tasks were solved during the study: 1 The existing researches of pile settlement are analyzed; 2 The characteristics of experimental studies and the parameters for numerical modeling are presented, methods of field research of single piles’ operation are described; 3 Calculation of single pile settlement is performed using numerical methods in the software package Plaxis 2D and analytical method according to the requirements SP 24.13330.2011; 4 Experimental data is compared with the results of analytical and numerical calculations; 5 Basing on these results recommendations for forecasting pile settlement on claystone are presented. Much attention is paid to the calculation of pile settlement considering the impacted areas in ground space beside pile and the comparison with the results of field experiments. Basing on the obtained results, for the prediction of settlement of single pile on claystone the authors recommend using the analytical method considered in SP 24.13330.2011 with account for the impacted areas in ground space beside driven pile. In the case of forecasting the settlement of single pile on claystone by numerical methods in Plaxis 2D the authors recommend using the Hardening Soil model considering the impacted areas in ground space beside the driven pile. The analyses of the results and calculations are presented for examination and verification; therefore it is necessary to continue the research work of deep foundation at another experimental sites to improve the reliability of the calculation of pile foundation settlement. The work is of great interest for geotechnical engineers engaged in research, design and construction of pile foundations.
Sadeghi, H.
2015-12-01
Bridges are major elements of infrastructure in all societies. Their safety and continued serviceability guaranties the transportation and emergency access in urban and rural areas. However, these important structures are subject to earthquake induced damages in structure and foundations. The basic approach to the proper support of foundations are a) distribution of imposed loads to foundation in a way they can resist those loads without excessive settlement and failure; b) modification of foundation ground with various available methods; and c) combination of "a" and "b". The engineers has to face the task of designing the foundations meeting all safely and serviceability criteria but sometimes when there are numerous environmental and financial constrains, the use of some traditional methods become inevitable. This paper explains the application of timber piles to improve ground resistance to liquefaction and to secure the abutments of short to medium length bridges in an earthquake/liquefaction prone area in Bohol Island, Philippines. The limitations of using the common ground improvement methods (i.e., injection, dynamic compaction) because of either environmental or financial concerns along with the abundance of timber in the area made the engineers to use a network of timber piles behind the backwalls of the bridge abutments. The suggested timber pile network is simulated by numerical methods and its safety is examined. The results show that the compaction caused by driving of the piles and bearing capacity provided by timbers reduce the settlement and lateral movements due to service and earthquake induced loads.
Directory of Open Access Journals (Sweden)
Ravi Kumar Reddy, C.
2014-01-01
Full Text Available This paper presents the effect of rigidity of plinth beam on a model building frame supported by pile groups embedded in cohesionless soil (sand through the results of static vertical load tests. The effect of rigidity of plinth beam on displacements and rotation at the column base and also shears and bending moments in the building frame were investigated. In the analytical model, soil nonlinearity in the axial direction is characterized by nonlinear vertical springs along the length of the pile (t-z curves and at the tip of the pile (Q-z curves while in the lateral direction by the p-y curves. Results revealed that, shear force and bending moment values which were back calculated from the experimental results, showed considerable reduction with the reduction of the rigidity of the plinth beam. The response of the frame from the experimental results is in good agreement with that obtained by the nonlinear finite element analysis.
Impedance function of a group of vertical piles
International Nuclear Information System (INIS)
Wolf, J.P.; Arx, G.A. von
1978-01-01
Impedance and transfer functions of a group of vertical piles located in any desired configuration in plan in a horizontally stratified soil layer are derived. Hysteretic and radiation damping are accounted for. The method separates the piles and the soil, introducing unknown interaction forces. The total flexibility matrix of the soil is constructed, superposing the (complex) flexibility coefficients caused by the interaction forces of a single pile only. The dependence of the impedance and transfer functions on the oscllating frequency for foundations with different numbers of piles is investigated. Pile-soil-pile interaction is shown to be very important for all modes of vibration. The procedure is used in the seismic analysis of a reactor building. (Author)
The reactor Cabri; La pile cabri
Energy Technology Data Exchange (ETDEWEB)
Ailloud, J.; Millot, J.P. [Commissariat a l' Energie Atomique, Cadarache (France). Centre d' Etudes Nucleaires
1964-07-01
exceptional circumstances... - experimental investigations on power excursions linked with precise initial conditions: the aim of this work is to define the basis for theoretical research, and the limits beyond which the risks of explosion cease to be negligible. The research work will be done so as to enable checking with outside reactor experiments and to continue them in the explosion field. - studies of the behaviour of the reactor control-instrumentation. - experimental investigations related with transient operation with initial short life (study of boiling, temperature measurements, vacuum pressure and fraction...) with the aim of defining the hypotheses of a theory on swimming-pool reactor kinetics related to heat transfer phenomena, - investigations of the behaviour of fuels in reactors (these experiments are planned to be carried out in loops) Preliminary experimental results. CABRI went critical on the 21 December 1963. The first transient experiments are expected for March 1964. (authors) [French] II devenait necessaire de construire en France une pile qui permette d'etudier les conditions de fonctionnement des installations futures, de choisir, tester et mettre au point les dispositifs de securite a adopter. On a choisi une pile a eau, type de pile qui correspond aux constructions les plus nouvelles du CEA en matiere de piles laboratoire ou d'universite; il importe en effet de pouvoir evaluer les risques presentes et d'etudier les possibilites d'augmentation de puissance constamment demandees par les utilisateurs: il est particulierement interessant d'eclaircir les phenomenes d'oscillation de puissance et les risques de calefaction (burn out). Les programmes de travaux sur CABRI seront harmonises avec les travaux effectues sur les Spert americains de meme type; lors de sa construction des contacts fructueux ont ete etablis avec les specialistes americains qui ont defini les premiers de ces reacteurs. La communication donne une
Viscoelastic modelling of Zircaloy cladding in-pile transient creep
Energy Technology Data Exchange (ETDEWEB)
Tulkki, Ville, E-mail: ville.tulkki@vtt.fi; Ikonen, Timo
2015-02-15
In fuel behaviour modelling accurate description of the cladding stress response is important for both operational and safety considerations. The cladding creep determines in part the width of the gas gap, the duration to pellet-cladding contact and the stresses to the cladding due to the pellet expansion. Conventionally the strain hardening rule has been used to describe the creep response to transient loads in engineering applications. However, it has been well documented that the strain hardening rule does not describe well results of tests with load drops or reversals. In our earlier work we have developed a model for primary creep which can be used to simulate the in- and out-of-pile creep tests. Since then several creep experiments have entered into public domain. In this paper we develop the model formulation based on the theory of viscoelasticity, and show that this model can reproduce the new experimental results. We also show that the creep strain recovery encountered in experimental measurements can be explained by viscoelastic behaviour.
Contiguous Pile Wall as a Deep Excavation Supporting System
Venkata Ramasubbarao GODAVARTHI; Dineshbabu MALLAVALLI; Ramya PEDDI; Neelesh KATRAGADDA; Prudhvikrishna MULPURU
2012-01-01
Providing space for parking, public amenities, etc in multi-storey buildings at town centres has created a need to go deep excavations into ground. Deep excavations are supported by systems like conventional retaining walls, sheet pile walls, braced walls, diaphragm walls and pile walls. This article describes various excavation supporting systems that are in vogue essentially contiguous pile wall and its advantages. A detailed design methodology of an excavation supporting system is furnishe...
Numerical Study on Soil Arching Effects of Stabilizing Piles
Fan, Fusong; Chen, Guangqi; Hu, Xinli; Wang, Wei
2015-01-01
The Soil arching effect, the transfer of soil pressure from the yielding soil to the piles support, is a phenomena commonly encountered in geotechnical engineering for stabilizing landslides. In this paper, the (finite element method) FEM and (discontinuous deformation analysis) DDA were used to study on the soil arching effects of stabilizing piles in landslides. This paper proposes a method for two dimensional numerical simulation to perform three dimensional soil-pile interaction so that t...
Neural networks and principle component analysis approaches to predict pile capacity in sand
Directory of Open Access Journals (Sweden)
Benali A
2018-01-01
Full Text Available Determination of pile bearing capacity from the in-situ tests has developed considerably due to the significant development of their technology. The project presented in this paper is a combination of two approaches, artificial neural networks and main component analyses that allow the development of a neural network model that provides a more accurate prediction of axial load bearing capacity based on the SPT test data. The retropropagation multi-layer perceptron with Bayesian regularization (RB was used in this model. This was established by the incorporation of about 260 data, obtained from the published literature, of experimental programs for large displacement driven piles. The PCA method is proposed for compression and suppression of the correlation between these data. This will improve the performance of generalization of the model.
Physical Modelling of Large Diameter Piles in Coarse-Grained Soil
DEFF Research Database (Denmark)
Brødbæk, K. T.; Augustesen, Anders Hust; Møller, M.
2011-01-01
design (e.g. [1] and [2]) is the effects of diameter on the initial part of the p-y curves. This part is especially important in connection with the serviceability limit state and fatigue. The effects of diameter on the p-y curves can be investigated by means of either numerical analyses or physical...... modelling (large- or small-scale). This paper investigates the effects of diameter on the initial part of the p-y curves by small-scale testing. A new and innovative test setup is presented. In order to minimize scale effects the tests are successfully carried out in a pressure tank enabling the possibility...... of increasing the effective stresses. The test setup is thoroughly described in the paper. Two non-slender aluminium pipe piles subjected to lateral loads have been tested in the laboratory. The piles are heavily instrumented with strain gauges in order to obtain p-y curves, displacement and bending moment...
Contiguous Pile Wall as a Deep Excavation Supporting System
Directory of Open Access Journals (Sweden)
Venkata Ramasubbarao GODAVARTHI
2012-08-01
Full Text Available Providing space for parking, public amenities, etc in multi-storey buildings at town centres has created a need to go deep excavations into ground. Deep excavations are supported by systems like conventional retaining walls, sheet pile walls, braced walls, diaphragm walls and pile walls. This article describes various excavation supporting systems that are in vogue essentially contiguous pile wall and its advantages. A detailed design methodology of an excavation supporting system is furnished in this study. A case study on the Contiguous pile wall retaining system for supporting a deep excavation at a town centre is presented.
Critical sizes and flux distributions in the shut down pile
International Nuclear Information System (INIS)
Banchereau, A.; Berthier, P.; Genthon, J.P.; Gourdon, C.; Lattes, R.; Martelly, J.; Mazancourt, R. de; Portes, L.; Sagot, M.; Schmitt, A.P.; Tanguy, P.; Teste du Bailler, A.; Veyssiere, A.
1957-01-01
An important part of the experiments carried out on the reactor G1 during a period of shut-down has consisted in determinations of critical sizes, and measurements of flux distribution by irradiations of detectors. This report deals with the following points: 1- Critical sizes of the flat pile, the long pile and the uranium-thorium pile. 2- Flux charts of the same piles, and study of an exponential experiment. 3- Determination of the slit effect. 4- Calculation of the anisotropy of the lattice. 5- Description of the experimental apparatus of the irradiation measurements. (author) [fr
Twin stability in highly nanotwinned Cu under compression, torsion and tension
DEFF Research Database (Denmark)
Hodge, A.M.; Furnish, T.A.; Shute, C.J.
2012-01-01
Twin stability under four distinct mechanical loading states has been investigated for highly nanotwinned Cu containing parallel nanotwins 40 nm thick. Observed deformation-induced microstructural changes under tension, compression, tension–tension fatigue and torsion are qualitatively compared...... in order to assess twin stability as a function of the loading direction and stress. It is observed that the twins are very stable although small microstructural changes vary with deformation mode. Shear bands, deformation-induced grain growth and detwinning are also discussed. © 2012 Acta Materialia Inc...
Torsion ratchet associated with mechanical hysteresis
International Nuclear Information System (INIS)
Han, S.; Wack, B.
1987-01-01
The experimental determination of behavior of material like metals, is often obtained with a tube shape sample. For the traction-compression and internal pressure test the direction of the solicitation principal axes is maintened constant. On the contrary the torsion test is a rotational solicitation and thus is accompagnied by secondary effects. For these reasons we conduct some cyclic torsion tests, with or without axial force, and attempt to measure as precisely as possible the axial deformation. The tests are run at a low strain rate and at room temperature so as to reduce as much as possible the influence of the viscosity phenomena and consequently to obtain results whose interpretation may be less complex. (orig./GL)
Torsion and transverse bending of cantilever plates
Reissner, Eric; Stein, Manuel
1951-01-01
The problem of combined bending and torsion of cantilever plates of variable thickness, such as might be considered for solid thin high-speed airplane or missile wings, is considered in this paper. The deflections of the plate are assumed to vary linearly across the chord; minimization of the potential energy by means of the calculus of variations then leads to two ordinary linear differential equations for the bending deflections and the twist of the plate. Because the cantilever is analyzed as a plate rather than as a beam, the effect of constraint against axial warping in torsion is inherently included. The application of this method to specific problems involving static deflection, vibration, and buckling of cantilever plates is presented. In the static-deflection problems, taper and sweep are considered.
Torsional asymmetry in suspension bridge systems
Czech Academy of Sciences Publication Activity Database
Malík, Josef
2015-01-01
Roč. 60, č. 6 (2015), s. 677-701 ISSN 0862-7940 R&D Projects: GA MŠk ED2.1.00/03.0082 Institutional support: RVO:68145535 Keywords : suspension bridge * Hamilton principle * vertical and torsional oscillation * uniqueness * existence Subject RIV: BA - General Mathematics Impact factor: 0.507, year: 2015 http://link.springer.com/article/10.1007%2Fs10492-015-0117-3
Torsion of a giant mesenteric lipoma
Energy Technology Data Exchange (ETDEWEB)
Wolko, Jonathan D.; Rosenfeld, David L.; Lazar, Michael J.; Underberg-Davis, Sharon J. [Department of Radiology, University of Medicine and Dentistry of New Jersey, Robert Wood Johnson Medical School, P.O. Box 19, New Brunswick, NJ 08903-0019 (United States)
2003-01-01
Mesenteric lipoma is a rare benign neoplastic condition that can grow to be very large and mimic other midgut fatty tumors. These benign tumors can cause various gastrointestinal symptoms such as obstruction and abdominal pain. We report the case of a 9-year-old boy who presented with a small bowel obstruction caused by torsion of a large mesenteric lipoma. This is an important but unusual tumor and should be considered in the differential of fatty lesions within the mesentery. (orig.)
Spacetime thermodynamics in the presence of torsion
Dey, Ramit; Liberati, Stefano; Pranzetti, Daniele
2017-12-01
It was shown by Jacobson in 1995 that the Einstein equation can be derived as a local constitutive equation for an equilibrium spacetime thermodynamics. With the aim to understand if such thermodynamical description is an intrinsic property of gravitation, many attempts have been made so far to generalize this treatment to a broader class of gravitational theories. Here we consider the case of the Einstein-Cartan theory as a prototype of theories with nonpropagating torsion. In doing so, we study the properties of Killing horizons in the presence of torsion, establish the notion of local causal horizon in Riemann-Cartan spacetimes, and derive the generalized Raychaudhuri equation for these kinds of geometries. Then, starting with the entropy that can be associated to these local causal horizons, we derive the Einstein-Cartan equation by implementing the Clausius equation. We outline two ways of proceeding with the derivation depending on whether we take torsion as a geometric field or as a matter field. In both cases we need to add internal entropy production terms to the Clausius equation as the shear and twist cannot be taken to be 0 a priori for our setup. This fact implies the necessity of a nonequilibrium thermodynamics treatment for the local causal horizon. Furthermore, it implies that a nonzero twist at the horizon in general contributes to the Hartle-Hawking tidal heating for black holes with possible implications for future observations.
Directory of Open Access Journals (Sweden)
Kacprzak Grzegorz
2015-06-01
Full Text Available A common engineering solution for excessive settlement with raft foundation (s is the use of piles in order to reduce the vertical displacements, in this method, the whole structural load is transferred to the piles. This is an overly cautious approach, and there remains a need to find an optimal design method for a building’s foundations. Such a solution may be the piled raft foundation, which allows a reduction of the number of piles due to the integration of the raft in the bearing capacity of the foundation. The aim of the article is to estimate the contribution of foundation elements such as the raft and the piles in the bearing capacity of a residential building located in Warsaw, where the geological conditions are characterized by organic soil layers, principally of gyttja.
Natural radioactivity at CBPP waste pile
International Nuclear Information System (INIS)
Kovac, Jadranka; Marovic, Gordana
2008-01-01
Electrical power requirements will necessitate doubling the present generating capacity in Croatia in the future. As a result, environmental discharges associated with the coal power industry will considerably increase. Burning of coal is one source of enhanced radiation exposure to naturally occurring elements, particularly members of uranium and thorium decay chains. By coal burning (in CBPP at about 1700 C degrees) the activity originating from uranium and thorium is redistributed from underground (where the impact on humanity is nil) and liberated into the environment. Most of the radioactive substances are concentrated in the ash and slag, which are heavy and drop to the bottom of a furnace, lately transported to deposit pile, from where some activity may leach into aquifer, or be dispersed by wind. Lighter fly ash, however, is carried up the chimney and into the atmosphere and irradiates people and contaminates food crops. Also, 222 Rn escapes into the atmosphere during incineration, while the non-gaseous members of the uranium decay series remain in the ash and slag. Extensive investigations have been performed in the coal burning power plant (CBPP) Plomin in Croatia and at deposit pile. A network of radon escalation measurements, in-situ gamma-spectrometric measurements and monitoring of waste pile were organized. The results of the measurements confirm that the ash/slag deposite site are well monitored and involve all the necessary protective measures. All obtained data can be used as a valuable database for future estimations and modeling of the impact of radioactive pollution to the marine environment. (author)
Threat from Rubble-Pile Asteroids
Schultz, P. H.
2015-12-01
While chondrites are the most common meteoroids to enter our atmosphere, they represent a small fraction of recovered falls. Most stony meteorites disrupt during entry, consumed by ablation or lost by weathering; in contrast, small iron meteorites (eyewitness of a crater formed by a stony meteorite; (b) undetected thermal entry at altitude; (c) no accessory meteorite falls; (d) "explosion" (not low-speed compression) crater; (e) infrasound/seismic data indicating a high-speed entry/collision; and (f) petrologic evidence for shock deformation/melting in breccias indicative of speeds >4 km/s. Although a monolithic chondrite (~ 10 m across) might allow surviving entry, most objects of this size contain multiple flaws, ensuring atmospheric disruption. Hence, an alternative "needle model" was proposed wherein a small rubble-pile object gradually re-shaped itself during entry [Schultz, 2008], a process that minimizes drag, thermal signatures of entry, and catastrophic disruption. First proposed to account for smaller than expected craters on Venus [Schultz, 1992], such a process resembles subsequent Shoemaker-Levy entry models [Boslough and Crawford, 1997] that predicted much deeper entry than standard models. Laboratory experiments at the NASA Ames Vertical Gun Range simulated this process by breaking-up hypervelocity projectiles into a cloud of debris and tracking its path at near-full atmospheric pressure. The resulting cloud of fragments exhibited less deceleration than a solid sphere at the same speed. Moreover, shadowgraphs revealed constituent fragments "surfing" the pressure jump within the mach cone/column. Previous models proposed that crater-forming impacts must be >50-100 m in diameter in order to survive entry [Bland and Artemieva, 2004]. The "needle model" for the Carancas meteorite entry, however, raises questions about this lower limit for threats by rubble-pile asteroids, e.g., Itokawa. Consequently, we modeled the fate of a rubble-pile entering earth
Visual in-pile fuel disruption experiments
International Nuclear Information System (INIS)
Cano, G.L.; Ostensen, R.W.; Young, M.F.
1978-01-01
In a loss-of-flow (LOF) accident in an LMFBR, the mode of disruption of fuel may determine the probability of a subsequent energetic excursion. To investigate these phenomena, in-pile disruption of fission-heated irradiated fuel pellets was recorded by high speed cinematography. Instead of fuel frothing or dust-cloud breakup (as used in the SAS code) massive and very rapid fuel swelling, not predicted by analytical models, occurred. These tests support massive fuel swelling as the initial mode of fuel disruption in a LOF accident. (author)
IP Controller Design for Uncertain Two-Mass Torsional System Using Time-Frequency Analysis
Directory of Open Access Journals (Sweden)
Jing Cui
2018-01-01
Full Text Available With the development of industrial production, drive systems are demanded for larger inertias of motors and load machines, whereas shafts should be lightweight. In this situation, it will excite mechanical vibrations in load side, which is harmful for industrial production when the motor works. Because of the complexity of the flexible shaft, it is often difficult to calculate stiffness coefficient of the flexible shaft. Furthermore, only the velocity of driving side could be measured, whereas the driving torque, the load torque, and the velocity of load side are immeasurable. Therefore, it is inconvenient to design the controller for the uncertain system. In this paper, a low-order IP controller is designed for an uncertain two-mass torsional system based on polynomial method and time-frequency analysis (TFA. IP controller parameters are calculated by inertias of driving side and load side as well as the resonant frequency based on polynomial method. Therein, the resonant frequency is identified using the time-frequency analysis (TFA of the velocity step response of the driving side under the open-loop system state, which can not only avoid harmful persistent start-stop excitation signal of the traditional method, but also obtain high recognition accuracy under the condition of weak vibration signal submerged in noise. The effectiveness of the designed IP controller is verified by groups of experiments. Experimental results show that good performance for vibration suppression is obtained for uncertain two-mass torsional system in a medium-low shaft stiffness condition.
Isolated Penile Torsion in Brothers: A Case Report
Directory of Open Access Journals (Sweden)
Metin Gunduz
2012-04-01
Full Text Available Penile torsion can be congenital and associated with hypospadias and chordee, or can be acquired after circumcision. The incidence of isolated neonatal penile torsion was 1.7 to 27% in the literature. The majority were between 10 and deg; and 20 and deg;. Generally, torsion was to the left in cases. The techniques for correction of penile torsion described in the literature are penile de-gloving and reattaching of skin, resection of Buck's fascia incising the base of the penis and removing angular ellipses of corporeal tissue with subsequent plication of tunica, and dorsal dartos flap rotation in severe cases. In conclusion, penile torsion may be familial. Therefore, brothers should be examined carefully. The degloving and realignment technique is successful in isolated penile torsion. [Arch Clin Exp Surg 2012; 1(2.000: 122-124
Fast Torsional Artificial Muscles from NiTi Twisted Yarns.
Mirvakili, Seyed M; Hunter, Ian W
2017-05-17
Torsional artificial muscles made of multiwalled carbon nanotube/niobium nanowire yarns have shown remarkable torsional speed and gravimetric torque. The muscle structure consists of a twisted yarn with half of its length infiltrated with a stimuli-responsive guest material such as paraffin wax. The volumetric expansion of the guest material creates the torsional actuation in the yarn. In the present work, we show that this type of actuation is not unique to wax-infiltrated carbon multiwalled nanotube (MWCNT) or niobium nanowire yarns and that twisted yarn of NiTi alloy fibers also produces fast torsional actuation. By gold-plating half the length of a NiTi twisted yarn and Joule heating it, we achieved a fully reversible torsional actuation of up to 16°/mm with peak torsional speed of 10 500 rpm and gravimetric torque of 8 N·m/kg. These results favorably compare to those of MWCNTs and niobium nanowire yarns.
Painless inter epididymal testicular torsion of the spermatic cord
Directory of Open Access Journals (Sweden)
Salomon V. Romano
2007-02-01
Full Text Available Inter epididymal testicular torsion of the spermatic cord is extremely rare and usually diagnosed at surgery. We present an unusual case of spermatic cord torsion in a 14-year-old male patient. It is important to highlight that the torsion occurred only on the distal half of the epididymis leaving the head untwisted and edematous. In addition, the fact that this condition was painless made this case extremely rare and motivated our presentation.
Painless inter epididymal testicular torsion of the spermatic cord
Salomon V. Romano; Haime S. Hernan; Norberto Fredotovich
2007-01-01
Inter epididymal testicular torsion of the spermatic cord is extremely rare and usually diagnosed at surgery. We present an unusual case of spermatic cord torsion in a 14-year-old male patient. It is important to highlight that the torsion occurred only on the distal half of the epididymis leaving the head untwisted and edematous. In addition, the fact that this condition was painless made this case extremely rare and motivated our presentation.
Secondary Torsion of Vermiform Appendix with Mucinous Cystadenoma
Maki Kitagawa; Tatsuya Kotani; Takeshi Yamano; Hideaki Tsurudome; Tomoya Hatakeyama; Yoshiaki Kuriu; Hiroshi Nishi; Masaharu Yabe
2007-01-01
Torsion of the vermiform appendix is a rare disorder, which causes abdominal symptoms indistinguishable from acute appendicitis. We report a case (a 34-year-old male) of secondary torsion of the vermiform appendix with mucinous cystadenoma. This case was characterized by mild inflammatory responses, pentazocine-resistant abdominal pain, and appendiceal tumor, which was not enhanced by the contrast medium on computed tomography presumably because of reduced blood flow by the torsion. These fin...
Wilson, William K; Morris, Randal P; Ward, Adam J; Carayannopoulos, Nikoletta L; Panchbhavi, Vinod K
2016-05-01
Carbon fiber composite implants are gaining popularity in orthopedics, but with few independent studies of their failure characteristics under supra-physiologic loads. The objective of this cadaveric study was to compare torsional failure properties of bridge plating a comminuted distal fibula fracture with carbon fiber polyetheretherketone (PEEK) composite and stainless steel one-third tubular plates. Comminuted fractures were simulated in 12 matched pairs of fresh-frozen human fibulas with 2-mm osteotomies located 3 cm proximal to the tibiotalar joint. Each fibula pair was randomized for fixation and implanted with carbon fiber and stainless steel 5-hole one-third tubular plates. The constructs were loaded in external rotation at a rate of 1-degree/sec until failure with a materials testing system. Torsional stiffness and mode of failure, as well as displacement, torque, and energy absorption for the first instance of failure and peak failure, were determined. Statistical analysis was performed with paired t tests and chi-square. There were no significant differences among the 12 pairs for torsional stiffness, first failure torque, peak failure displacement, peak failure torque, or peak failure energy. Stainless steel plates exhibited significantly higher displacement (P fibula fracture fixation model, carbon fiber implants exhibited multiple pre-peak failures at significantly lower angles than the first failure for the stainless steel implants, with some delamination of composite layers and brittle catastrophic failure rather than plastic deformation. The torsional failure properties of carbon fiber composite one-third tubular plates determined in this independent study provide novel in vitro data for this alternative implant material. © The Author(s) 2016.
Isolated fallopian tube torsion during pregnancy: a case report.
Lee, D H; Park, Y K
2015-01-01
Isolated fallopian tube torsion is a rare pregnancy-related complication. It is frequently misdiagnosed as acute appendicitis or ovarian torsion owing to the lack of specific symptoms or signs. Here, the authors report a case of a 35-year-old primigravida at 30 weeks and six days of gestation who had presented with right isolated fallopian tube torsion and a history of right oophorectomy. The authors propose that isolated fallopian tube torsion should be included in the list of differential diagnosis when encountered with patients complaining of lower abdominal pain.
Ultrasonographic features of prenatal testicular torsion: Case report
Directory of Open Access Journals (Sweden)
Elif Ağaçayak
2013-01-01
Full Text Available Although prenatal testicular torsion (PNTT is rarely observed,it is an important condition that can cause bilateralvanishing testis. Generally, PNTT cases observed asextravaginal torsion and treatment is emergency surgicalop-eration. In this article, 39 week presented a case diagnosedin the prenatal testicular torsion. PNTT diagnosiswas confirmed by Doppler ultrasonography and emergencysurgery was performed. Extravaginal left testiculartorsion gangrene and necrosis of the testis was observedin the operation. Left orchiectomy was performed andintrauter-ine ultrasonographic diagnosis was found to becorrect.Key words: Testicular torsion, prenatal diagnosis, features,ultrasonography
Secondary Torsion of Vermiform Appendix with Mucinous Cystadenoma
Directory of Open Access Journals (Sweden)
Maki Kitagawa
2007-06-01
Full Text Available Torsion of the vermiform appendix is a rare disorder, which causes abdominal symptoms indistinguishable from acute appendicitis. We report a case (a 34-year-old male of secondary torsion of the vermiform appendix with mucinous cystadenoma. This case was characterized by mild inflammatory responses, pentazocine-resistant abdominal pain, and appendiceal tumor, which was not enhanced by the contrast medium on computed tomography presumably because of reduced blood flow by the torsion. These findings may be helpful for the preoperative diagnosis of secondary appendiceal torsion.
Torsion of vermiform appendix with fecalith: a case report
Wani, Imtiaz; Kitagawa, Maki; Rather, Mudasir; Singh, Jang; Bhat, Gulam; Nazir, Mir
2008-01-01
Introduction Torsion of the vermiform appendix is a rare disorder, which causes abdominal symptoms indistinguishable from acute appendicitis and is found by chance during the laparotomy. Case presentation We report a case (a 76-year-old male) suffering of torsion of the vermiform appendix with fecalith. It was twisted 540 degrees in an anti-clockwise direction. Appendectomy was done. Conclusion Appendiceal torsion may be assocated with the presence of fecalith. This case is the oldest one among the patients with appendiceal torsion reported to literature. PMID:18577201
Secondary Torsion of Vermiform Appendix with Mucinous Cystadenoma
Kitagawa, Maki; Kotani, Tatsuya; Yamano, Takeshi; Tsurudome, Hideaki; Hatakeyama, Tomoya; Kuriu, Yoshiaki; Nishi, Hiroshi; Yabe, Masaharu
2007-01-01
Torsion of the vermiform appendix is a rare disorder, which causes abdominal symptoms indistinguishable from acute appendicitis. We report a case (a 34-year-old male) of secondary torsion of the vermiform appendix with mucinous cystadenoma. This case was characterized by mild inflammatory responses, pentazocine-resistant abdominal pain, and appendiceal tumor, which was not enhanced by the contrast medium on computed tomography presumably because of reduced blood flow by the torsion. These findings may be helpful for the preoperative diagnosis of secondary appendiceal torsion. PMID:21487469
Piling up technology of goods irradiated by single plate source
International Nuclear Information System (INIS)
Xia Hezhou; Chen Yuxia; Cao Hongyun; Lin Yong; Zhou guoquan
1999-01-01
In the irradiation process of piling up goods in static state, four irradiation working sites and single plate source was adopted. The results showed that piling up in this way remarkably raised the irradiation quality of goods. The utilization rate of radioactive ray reached 22.27%
Visualization of soil arching in flexible piled embankments
Indian Academy of Sciences (India)
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 ...
Assessment of timber piles in Clallam County, Washington
Pandey, Arun K.; Tyler, Ross; Arnette, Clyde G.; Anthony, Ronald W.
1998-03-01
Timber bridges are very common in state and rural highway systems. According to the National Bridge Inventory (NBI), there are 41,743 timber bridges in the United States and another 42,102 bridges with timber decks as a part of the superstructure. As these bridges age, there is a critical need for reliable inspection and assessment methods for evaluating timber members. Under an FHWA mandate, these bridges also need to be evaluated for scour susceptibility. Knowledge of the length of timber piles supporting the bridge is a vital component in calculating scour resistance of a bridge. However, records of timber pile lengths are often nonexistent or incomplete due to the construction practices for timber piles. This paper presents nondestructive evaluation (NDE) techniques used for assessing timber piles on 10 bridges in Clallam County, Washington. Stress wave velocity and resistance drilling techniques were used to determine the presence of and quantify the extent of decay in the piles. A longitudinal stress wave technique was used for determining the length of timber piles. Determination of piles with decay aided in establishing maintenance and repair needs on the bridge substructures. Pile length estimates enabled Clallam County Road Department to determine the scour-susceptibility of these bridges.
Effect of piles on the seismic response of mosques minarets
Directory of Open Access Journals (Sweden)
Mohamed Ahmed Abdel-Motaal
2014-03-01
Minaret (60.0-m height was studied to investigate the effects of soil stiffness, pile length, diameter, and arrangement, on the minaret and pile dynamic behavior. Comparison between study results and conventional analysis method is illustrated. Study results, discussion, and conclusion are given.
Optimising the bio-piling of weathered hydrocarbons within a risk management framework
International Nuclear Information System (INIS)
Hough, R.; Brassington, K.; Sinke, A.; Crossley, J.; Paton, G.; Semple, K.; Risdon, G.; Jacobson, Ch.; Daly, P.; Jackman, S.; Lethbridge, G.; Pollard, S.
2005-01-01
Thirty years of research into petroleum microbiology and bio-remediation have bypassed an important observation - that many hydrocarbon contaminated sites posing potential risks to human health harbour weathered, 'mid-distillate' or heavy oils rather than 'fresh product'. Ex-situ bio-piling is an important technology for treating soils contaminated with weathered hydrocarbons. However, its performance continues to be represented by reference to reductions in the hydrocarbon 'load' in the soils being treated, rather than reductions in the risks posed by the hydrocarbon contamination. The absence of 'risk' from the vocabulary of many operators and remediation projects reduces stakeholder (regulatory, investor, landowner, and public) confidence in remediation technologies, and subsequently limits the market potential of these technologies. Stakeholder confidence in the bio-piling of weathered hydrocarbons may be improved by demonstrating process optimisation within a validated risk management framework. To address these issues, a consortium led by Cranfield University's Integrated Waste Management Centre has secured funding from the UK Government's Bio-remediation LINK programme. Project PROMISE (involving BP, SecondSite Regeneration Ltd., Dew Remediation Ltd., TES Bretby (Mowlem Group), technology translators PERA, and academics from Aberdeen, Cranfield and Lancaster Universities) aims to improve market confidence in bio-piling by demonstrating how this treatment may be applied within a risk management context. For weathered hydrocarbons in particular, the underpinning scientific components of process control, waste diagnostics, environmental fate modelling, and risk assessment have yet to be fully integrated to allow bio-piling projects to be verified with improved confidence. The Joint Research Council Review of Bio-remediation recognised this in calling explicitly for the positioning of bio-remediation within a risk management framework. The PERF report (Thermo
The Analysis of Soil Resistance During Screw Displacement Pile Installation
Directory of Open Access Journals (Sweden)
Krasinski Adam
2015-02-01
Full Text Available The application of screw displacement piles (SDP is still increasing due to their high efficiency and many advantages. However, one technological problem is a serious disadvantage of those piles. It relates to the generation of very high soil resistance during screw auger penetration, especially when piles are installed in non-cohesive soils. In many situations this problem causes difficulties in creating piles of designed length and diameter. It is necessary to find a proper method for prediction of soil resistance during screw pile installation. The analysis of screw resistances based on model and field tests is presented in the paper. The investigations were carried out as part of research project, financed by the Polish Ministry of Science and Higher Education. As a result of tests and analyses the empirical method for prediction of rotation resistance (torque during screw auger penetration in non-cohesive subsoil based on CPT is proposed.
Optimal Design of Sheet Pile Wall Embedded in Clay
Das, Manas Ranjan; Das, Sarat Kumar
2015-09-01
Sheet pile wall is a type of flexible earth retaining structure used in waterfront offshore structures, river protection work and temporary supports in foundations and excavations. Economy is an essential part of a good engineering design and needs to be considered explicitly in obtaining an optimum section. By considering appropriate embedment depth and sheet pile section it may be possible to achieve better economy. This paper describes optimum design of both cantilever and anchored sheet pile wall penetrating clay using a simple optimization tool Microsoft Excel ® Solver. The detail methodology and its application with examples are presented for cantilever and anchored sheet piles. The effects of soil properties, depth of penetration and variation of ground water table on the optimum design are also discussed. Such a study will help professional while designing the sheet pile wall penetrating clay.
Directory of Open Access Journals (Sweden)
H. W. Yang
2015-11-01
Full Text Available In this study, the performance of pile foundation is assessed for the 30 km long viaduct bridge structure seating in the ground subsidence area in the central part of Taiwan. The focus of this paper is placed on the settlement behaviour of a continuous 3-span R. C. viaduct bridge supported on piles adjacent to highway embankment. Monitoring data accumulated over the last 12 years indicate that the observed pace of the settlement of the viaduct structure in other sections matches that of the ground. However, the bridge piers adjacent to the embankment have been suffering an additional approximately 1 cm settlement every year since the completion of the embankment construction. It was believed that the piers may suffer from enormous negative skin friction owing to the surcharge from the embankment and groundwater depression. This paper first summarizes the settlement analysis results to quantify the settlement of pile due to regional ground subsidence and the combined effects from ground water fluctuation and embankment surcharge loading. Accordingly, a loading path on P'-q stress space is formulated to illustrate the loading variation subject to the combined loading effects that can explain why the combined effect becoming significant on settlement control for civil infrastructure in ground subsidence area.
Directory of Open Access Journals (Sweden)
Chenchen Jiang
2016-03-01
Full Text Available Fatigue behavior of nanomaterials could ultimately limit their applications in variable nano-devices and flexible nanoelectronics. However, very few existing nanoscale mechanical testing instruments were designed for dedicated fatigue experiments, especially for the challenging torsional cyclic loading. In this work, a novel high-cycle torsion straining micromachine, based on the digital micromirror device (DMD, has been developed for the torsional fatigue study on various one-dimensional (1D nanostructures, such as metallic and semiconductor nanowires. Due to the small footprint of the DMD chip itself and its cable-remote controlling mechanisms, it can be further used for the desired in situ testing under high-resolution optical or electron microscopes (e.g., scanning electron microscope (SEM, which allows real-time monitoring of the fatigue testing status and construction of useful structure-property relationships for the nanomaterials. We have then demonstrated its applications for testing nanowire samples with diameters about 100 nm and 500 nm, up to 1000 nm, and some of them experienced over hundreds of thousands of loading cycles before fatigue failure. Due to the commercial availability of the DMD and millions of micromirrors available on a single chip, this platform could offer a low-cost and high-throughput nanomechanical solution for the uncovered torsional fatigue behavior of various 1D nanostructures.
Improving the bearing capacity of footing on soft clay with sand pile with/without skirts
Directory of Open Access Journals (Sweden)
Ashraf Kamal Nazir
2010-12-01
Full Text Available This paper presents the results of laboratory model tests for studying the improvement of soft clay layer by using both partially replaced sand piles with/without confinement. This research is performed to study the effect of sand pile to improve the bearing capacity and to control the settlement. Also the research aimed at investigating the variation of subgrade modulus, and the induced failure mechanism of shallow circular footing on replaced soil with/without skirts. The results show that the improvement of load bearing capacity is remarkable; using both partially replaced sand pile with and without confinement by skirts. The adopted technique can substantially modify the stress displacement curve of the footing rested on soft clay layer, significantly decreases the settlement and the replaced soil block inside the skirts behave as deep foundation. Therefore, the bearing capacity failure mechanism of a footing rested on soft clay can be modified from exclusive settlement to general bearing capacity failure at the tip of confined replaced sand column.
Numerical Analysis of Helical Pile–Soil Interaction under Compressive Loads
Polishchuk, A. I.; Maksimov, F. A.
2017-11-01
The results of the field tests of full-scale steel helical piles in clay soils intended for prefabricated temporary buildings foundations are presented in this article. The finite element modeling was used for the evaluation of stress distribution of the clay soil around helical piles. An approach of modeling of the screw-pile geometry has been proposed through the Finite Element Analysis. Steel helical piles with a length of 2.0 m, shaft diameter of 0.108 m and a blade diameter of 0.3 m were used in the experiments. The experiments have shown the efficiency of double-bladed helical piles in the clay soils compared to single-bladed piles. It has been experimentally established that the introduction of the second blade into the pile shaft provides an increase of the bearing capacity in clay soil up to 30% compared to a single-bladed helical pile with similar geometrical dimensions. The numerical results are compared with the measurements obtained by a large scale test and the bearing capacity has been estimated. It has been found that the model results fit the field results. For a double-bladed helical pile it was revealed that shear stresses upon pile loading are formed along the lateral surface forming a cylindrical failure surface.
Toward laboratory torsional spine magnetic reconnection
Chesny, David L.; Orange, N. Brice; Oluseyi, Hakeem M.; Valletta, David R.
2017-12-01
Magnetic reconnection is a fundamental energy conversion mechanism in nature. Major attempts to study this process in controlled settings on Earth have largely been limited to reproducing approximately two-dimensional (2-D) reconnection dynamics. Other experiments describing reconnection near three-dimensional null points are non-driven, and do not induce any of the 3-D modes of spine fan, torsional fan or torsional spine reconnection. In order to study these important 3-D modes observed in astrophysical plasmas (e.g. the solar atmosphere), laboratory set-ups must be designed to induce driven reconnection about an isolated magnetic null point. As such, we consider the limited range of fundamental resistive magnetohydrodynamic (MHD) and kinetic parameters of dynamic laboratory plasmas that are necessary to induce the torsional spine reconnection (TSR) mode characterized by a driven rotational slippage of field lines - a feature that has yet to be achieved in operational laboratory magnetic reconnection experiments. Leveraging existing reconnection models, we show that within a 3$ apparatus, TSR can be achieved in dense plasma regimes ( 24~\\text{m}-3$ ) in magnetic fields of -1~\\text{T}$ . We find that MHD and kinetic parameters predict reconnection in thin current sheets on time scales of . While these plasma regimes may not explicitly replicate the plasma parameters of observed astrophysical phenomena, studying the dynamics of the TSR mode within achievable set-ups signifies an important step in understanding the fundamentals of driven 3-D magnetic reconnection and the self-organization of current sheets. Explicit control of this reconnection mode may have implications for understanding particle acceleration in astrophysical environments, and may even have practical applications to fields such as spacecraft propulsion.
Transverse posterior element fractures associated with torsion
International Nuclear Information System (INIS)
Abel, M.S.
1989-01-01
Six examples of a previously undescribed class of transverse vertebral element fractures are presented. These fractures differ from Chance and Smith fractures and their variants in the following respects: (1) the etiology is torsion and not flexion; (2) there is neither distraction of posterior ring fragments nor posterior ligament tears; (3) in contrast to Chance and Smith fractures, extension of the fracture into the vertebral body is absent or minimal; (4) the transverse process of the lumbar vertebra is avulsed at its base with a vertical fracture, not split horizontally. These fractures occur in cervical, lumbar, and sacral vertebrae in normal or compromised areas of the spine. (orig.)
Possible role of torsion in gravitational theories
International Nuclear Information System (INIS)
Nieh, H.T.
1983-01-01
Torsion is of interest in an indirect way, in that it has the potential of being an important ingredient in a future successful quantum theory of gravitation. Einstein's theory of gravitation, despite its simplicity and elegance, and its successes in large-scale gravitational phenomena, can only be regarded as a macroscopic classical theory. It is a non-renormalizable quantum field theory, and, therefore, lacks the status of a good microscopic theory. It is the search for a successful quantum field theory of gravitation that poses as one of the great challenges to theoretical physics today. (Auth.)
DETERMINING A SUFFICIENT DEPTH OF PILE FOUNDATION ON THE PERTAMINA GRAVING DOCK DESIGN SORONG PAPUA
Directory of Open Access Journals (Sweden)
Franto Novico
2017-07-01
Full Text Available Engineering geological aspect and bearing capacity of pile foundation are significant for safety of upper structure, especially for substantial constructions such as a docking ship. Moreover, it provides effectiveness and cost efficiency when applies in rural areas of Indonesia. This is due to lack of docking ship appropriately built at rural areas particularly in eastern areas of Indonesia. Karim island of Papua even though is a small island yet is very strategic as Pertamina place its transitory function on that island connecting its oil supply route to Sorong. Appropriate docking ship construction is required to aim the effective and efficient port management. Choosing the most suitable structure for a docking is also the key. Graving dock structure has been chosen by Pertamina as the most appropriate type of structure for the docking ship in Karim Island. The structure of graving dock planned to be built in Karim island Papua, is projected to be able to serve the maximum 7500 DWT ship capacity, with approximately dimension is 125 x 25 x 8 meters. Therefore, to support the plan, type and design of the best foundation is the key. There are two methods could be done in determining the type and bearing capacity foundation. Field and laboratory test applied ASTM, field observation result by applying Meyerhoff theory and laboratorial analysis derived from Tarzaghi theory. Those observation and analysis has confirmed that the soil layer at the graving dock design consists of three layers, those are; cover layer, silt-clay layer and clay rock unit. Therefore, the most suitable foundation to be constructed in that area is a pile massive foundation, with depth of pile foundation approximately -20 m below the land surface, and the ultimate point load pile massive for 30x30 cm - 75x75 cm dimension approximately 79.76 â€“ 406.25 ton, and frictional resistance value approximately 24.59-61.48 ton.
Digitalisation in atomic pile control (1962)
International Nuclear Information System (INIS)
Furet, J.
1962-01-01
A brief survey is first given of the general theorems of Boodle's algebra and of sequence systems using D.A. Huffmans theory. Some indications are then given concerning the setting-up and the operation of digital computers and also of the principal codes used in digital techniques. It is then shown how digitalisation in atomic pile control makes it possible to use new techniques having the following advantages in particular: greater working safety, a higher degree of centralisation, and suppression of the linear elements. A few examples are given of the application of these techniques to control, particularly with respect to the measurement of the neutronic power and of the period and also of course, to the treatment of the data and the sequence automatisms. The advantage of using digital techniques in the shutdown channels is also examined. Finally a review is given of the technology and the viability of the control devices used. (author) [fr
Ultimate limit state design of sheet pile walls by finite elements and nonlinear programming
DEFF Research Database (Denmark)
Krabbenhøft, Kristian; Damkilde, Lars; Krabbenhøft, Sven
2005-01-01
The design of sheet pile walls by lower bound limit analysis is considered. The design problem involves the determination of the necessary yield moment of the wall, the wall depth and the anchor force such that the structure is able to sustain the given loads. This problem is formulated...... as a nonlinear programming problem where the yield moment of the wall is minimized subject to equilibrium and yield conditions. The finite element discretization used enables exact fulfillment of these conditions and thus, according to the lower bound theorem, the solutions are safe....
Ultimate Limit State Design Of Sheet Pile Walls By Finite Elements And Nonlinear Programming
DEFF Research Database (Denmark)
Krabbenhøft, Kristian; Damkilde, Lars; Krabbenhøft, Sven
2005-01-01
The design of sheet pile walls by lower bound limit analysis is considered. The design problem involves the determination of the necessary yield moment of the wall, the wall depth and the anchor force such that the structure is able to sustain the given loads. This problem is formulated...... as a nonlinear programming problem where the yield moment of the wall is minimized subject to equilibrium and yield conditions. The finite element discretization used enables exact fulfillment of these conditions and thus, according to the lower bound theorem, the solutions are safe...
Correlation of severity of penile torsion with type of hypospadias ...
African Journals Online (AJOL)
Objective: This study was carried out to evaluate the correlation between the severity of penile torsion on the one hand and the degree of ventral penile curvature and the type of hypospadias on the other. We also assessed the effectiveness of correction of chordee and torsion by penile degloving and mobilization of the ...
Perinatal testicular torsion: literature review and local experience ...
African Journals Online (AJOL)
The prognosis in TUDT is guarded and contralateral fixation was not practiced, except in a 5-week-old infant. Early orchiopexy at 3–6 months is recommended. Cooperation between surgeons, neonatologists, and parents is mandatory to avoid time delay. Keywords: intrauterine testicular torsion, postnatal testicular torsion, ...
Torsion of the Spermatic Cord: Is Bilateral Orchidopexy Really ...
African Journals Online (AJOL)
Aim: To evaluate the rationale for bilateral orchidopexy as treatment for unilateral torsion of the testis, by determining how frequently the contralateral testis shows an abnormal pathology in unilateral testicular torsion. Patients and Methods:This is a retrospective study using adult urology patients treated for both acute and ...
experimental and analytical comparison of torsion, bending moment
African Journals Online (AJOL)
HOD
by shear design. Less attention was paid in the past by reinforced concrete designers to these effects of torsion in reinforced concrete members. When torsion is encountered in reinforced ... and composite nature of the material and presence of cracks [2]. .... principles and some limited design equations for a generalized ...
Penile Torsion: an Overlooked Anomaly with Distal Hypospadias
African Journals Online (AJOL)
HussamHassan
with posterior hypospadias had associating penile torsion. Follow-up showed satisfactory correction of penile torsion in 3 out of 9 patients in group A; and in 8 out of ... using MillenMed DICOM viewer program for image analysis, based on the orientation of the urethral groove (meatus) relative to the vertical position (fig. B). P ...
A Patient Presenting with Concurrent Testis Torsion and Epididymal Leiomyoma
Directory of Open Access Journals (Sweden)
E. Arpali
2013-01-01
Full Text Available Leiomyomas are the second most common tumors of epididymis. Patients with leiomyomas are sometimes misdiagnosed with testicular tumors. A Case of a patient with a scrotal mass presenting with testicular torsion is reported. Concurrent occurrence of testicular torsion and epididymal leiomyoma is an extremely rare condition.
Torsion of right middle lobe after a right upper lobectomy
Directory of Open Access Journals (Sweden)
Chen Tung-Ying
2009-04-01
Full Text Available Abstract Lobar torsion after lung resection is a quite rare complication. A 50-year-old woman presented typical features on chest radiographs and CT(computed tomography scan of lobar torsion after a right upper lobectomy. After emergency lobectomy of right middle lobe, the patient recovered well and discharged 10 days after the second operation.
Prediction of Torsional Strength for Very High Early Strength Geopolymer
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Woraphot PRACHASAREE
2017-11-01
Full Text Available Very early high strength geopolymers are gaining acceptance as alternative repair materials for highways and other infrastructure. In this study, a very rapid geopolymer binder based on Metakaolin (MK and Parawood ash (PWA, developed by the authors, was experimentally tested and a prediction model for its torsional strength is proposed. The geopolymer samples were subjected to uniaxial compression, flexural beam, and torsion tests. The modulus of rupture and torsional strength in terms of compression strength were found to be well approximated by 0.7(f’c1/2 and 1/7(x2y (f’c1/2, respectively. Also an interaction relation to describe combined bending and torsion was developed in this study. In addition, the effects of aspect ratio (y/x were studied on both torsional strength and combined bending and torsion. It was found that an aspect ratio of y/x = 3 significantly reduced the torsional resistance, to about 50 % of the torsional strength of a square section.DOI: http://dx.doi.org/10.5755/j01.ms.23.4.17280
Torsion of the Spermatic Cord: An Exemplary Early Presentation ...
African Journals Online (AJOL)
... still the norm. In the index patient, the presentation time was very short. In our environment, patients with torsion of the spermatic cord can present early and be operated promptly if we can provide public health education, mobile phones, commercial taxis, and good road networks. Keywords: Spermatic cord, testis, torsion ...
Manual Detorsion of Testicular Torsion - A Primary Care Intervention ...
African Journals Online (AJOL)
Testicular torsion is one of the known acute urological emergencies that require prompt intervention. Salvage of the testis is only possible if derotation is performed within 6 hours of onset of symptoms. The objective of this paper is to report successful manual detorsion of the testes of patients with testicular torsion.
Effect of irregularity on torsional surface waves in an initially ...
Indian Academy of Sciences (India)
Effect of irregularity on torsional surface waves in an initially stressed anisotropic porous layer sandwiched between homogeneous and non-homogeneous half- ... Torsional wave; anisotropy; initial stress; irregularity; non-homogeneity ... Department of Applied Mathematics, Indian School of Mines, Dhanbad 826 004, India.
Case series on testicular torsion: an educational emergency for sub ...
African Journals Online (AJOL)
305 records ... Testicular torsion remains a common surgical emergency of adolescent males presenting with sudden onset of intense scrotal pain in Africa. While the magnitude of testicular torsion is not known it has been identified as a cause of male infertility. Testicular loss in Africa is directly related to delay in surgery and ...
CONSTRAINING SPACETIME TORSION WITH THE MOON, MERCURY AND LAGEOS
Directory of Open Access Journals (Sweden)
Riccardo March
2013-12-01
Full Text Available We consider an extension of Einstein General Relativity where, beside the Riemann curvature tensor, we suppose the presence of a torsion tensor. Using a parametrized theory based on symmetry arguments, we report on some results concerning the constraints that can be put on torsion parameters by studying the orbits of a test body in the solar system.
Severe congenital penile torsion with anterior urethral diverticulum ...
African Journals Online (AJOL)
On examination, he was found to be a case of severe congenital penile torsion with diversion and rotation of median raphae in a counterclockwise fashion upto the midline dorsally confirming 180◦ torsion. During voiding, there was appearance of a swelling in distal penile region with passage of urinary drops while ...
Intermittent Testicular Torsion | Obi | Nigerian Journal of Clinical ...
African Journals Online (AJOL)
Methods: Clinical and demographic data of all patients treated for intermittent testicular torsion from January 2007 to June 2015 were prospectively collected in a pro forma and analyzed. A diagnosis of intermittent torsion was made on the basis of recurrent scrotal pain, presence of abnormal testicular lie in otherwise normal ...
Primary omental torsion in children: case report | Khalid | Pan ...
African Journals Online (AJOL)
Primary omental torsion in children: case report. Khattala Khalid, Tenorkorang Snr Somuah, Elmadi Aziz, Rami Mohamed, Bouabdallah Youssef. Abstract. Primary omental torsion is a rare cause of acute abdominal pain, we report a case of 10-year-old boy admitted with crampy abdominal pain, routine laboratory tests and ...
The Metal Hoard from Pile in Scania, Sweden
DEFF Research Database (Denmark)
Vandkilde, Helle
The metal hoard from Pile has branded the onset of the rich Nordic Bronze Age since its discovery in 1864 at the coast of Scania in southwestern Sweden. Yet, this book provides the first detailed documentation, scientific examination and historical interpretation. Indeed, Pile emerges as the earl......The metal hoard from Pile has branded the onset of the rich Nordic Bronze Age since its discovery in 1864 at the coast of Scania in southwestern Sweden. Yet, this book provides the first detailed documentation, scientific examination and historical interpretation. Indeed, Pile emerges...... as the earliest, finest and among the largest of the Nordic sacrificial deposits of metalwork in watery settings. In this book, Pile figures as a place at the brim of the sea as much as an ensemble of exquisite things and coppers that arrived to Scandinavia from various parts of Europe around 2000 BCE. Pile...... was a maritime node and a landing place for exogenous metals and exotic daggers and rings, but also a site where the smith produced coveted axes for wider distribution locally and regionally. Such robust axes of ‘Pile-type’ boosted the political economy of Southern Scandinavia 2100-1700 BCE while adding to a hot...
Turbulence Modeling of Torsional Couette Flows
Directory of Open Access Journals (Sweden)
Sofia Haddadi
2008-01-01
Full Text Available The present study considers the numerical modeling of the turbulent flow inside a rotor-stator cavity subjected or not to a superimposed throughflow. Extensive numerical predictions based on one-point statistical modeling using a low Reynolds number second-order full stress transport closure (RSM model are performed mainly in the case of turbulent flows with merged boundary layers known as turbulent torsional Couette flows and belonging to regime III of Daily and Nece (1960. The RSM model has already shown its capability of predicting accurately the mean and turbulent fields in various rotating disk configurations (Poncet, 2005; Poncet et al., 2005, 2007, 2008. For the first time, a detailed mapping of the hydrodynamic flow over a wide range of rotational Reynolds numbers (180 000≤Re≤10 000 000, aspect ratios of the cavity (0.02≤G≤0.05, and flow rate coefficients (−10000≤Cw≤10000 is here provided in the turbulent torsional Couette flow regime.
Lung lobe torsion in seven juvenile dogs.
Latimer, Christian R; Lux, Cassie N; Sutton, Jessie S; Culp, William T N
2017-12-15
CASE DESCRIPTION 7 juvenile (< 12 months old) dogs with lung lobe torsion were evaluated. CLINICAL FINDINGS All patients were male; breeds included Pug (n = 5), Chinese Shar-Pei (1), and Bullmastiff (1). Dyspnea and lethargy were the most common initial complaints, with a duration of clinical signs ranging from 1 to 10 days. A CBC showed leukocytosis and neutrophilia in all dogs. Anemia was present in 6 dogs, 2 of which received packed RBC transfusions. The diagnosis was made on the basis of results of thoracic radiography, CT, ultrasonography, or a combination of modalities. The left cranial lung lobe was most commonly affected (n = 4), followed by the right middle lung lobe (2) and the right cranial lung lobe (1). TREATMENT AND OUTCOME A lateral intercostal thoracotomy with lobectomy of the affected lobe was performed in all patients. All dogs survived to be discharged between 1 and 2 days postoperatively. Six of 7 owners contacted for follow-up information 7 to 170 months after discharge reported satisfaction with the treatment and no apparent signs of recurrence of disease. CLINICAL RELEVANCE The juvenile patients of this report were successfully treated surgically with no apparent complications. Clinicians should be aware of the possibility of lung lobe torsion when evaluating young dogs with clinical signs related to the respiratory system, including those with vague signs, to avoid undue delays in treatment.
The Reidemeister torsion of 3-manifolds
Nicolaescu, Liviu I
2003-01-01
This is a state-of-the-art introduction to the work of Franz Reidemeister, Meng Taubes, Turaev, and the author on the concept of torsion and its generalizations. Torsion is the oldest topological (but not with respect to homotopy) invariant that in its almost eight decades of existence has been at the center of many important and surprising discoveries. During the past decade, in the work of Vladimir Turaev, new points of view have emerged, which turned out to be the "right ones" as far as gauge theory is concerned. The book features mostly the new aspects of this venerable concept. The theoretical foundations of this subject are presented in a style accessible to those, who wish to learn and understand the main ideas of the theory. Particular emphasis is upon the many and rather diverse concrete examples and techniques which capture the subleties of the theory better than any abstract general result. Many of these examples and techniques never appeared in print before, and their choice is often justified by ...
Directory of Open Access Journals (Sweden)
N. Bachschmid
2004-01-01
Full Text Available In this article, the deflections of a circular cross-section beam presenting a transverse crack of different depths, due to different loads (bending, torsion, shear, and axial loads, are analyzed with the aid of a rather refined 3-D model, which takes into account the nonlinear contact forces in the cracked area. The bending and shear loads are applied in several different angular positions, in order to simulate a rotating load on a fixed beam, or, by changing the reference system, a fixed load on a rotating beam. Torsion and axial loads are instead fixed with respect to the beam.
Directory of Open Access Journals (Sweden)
Nicolò Bachschmid
2003-01-01
Full Text Available In this article the deflections of a circular cross-section beam presenting a transverse crack of varying depths caused by various loads (bending, torsion, shear, and axial loads are analyzed with the aid of a rather refined three-dimensional model that takes into account the nonlinear contact forces in the cracked area. The bending and shear loads are applied in several different angular positions in order to simulate a rotating load on a fixed beam or, by changing the reference system, a fixed load on a rotating beam. Torsion and axial loads are fixed with respect to the beam.
Krukenberg Tumor: A Rare Cause of Ovarian Torsion
Directory of Open Access Journals (Sweden)
Sameer Sandhu
2012-01-01
Full Text Available Ovarian torsion is the fifth most common gynecological surgical emergency. Ovarian torsion is usually associated with a cyst or a tumor, which is typically benign. The most common is mature cystic teratoma. We report the case of a 43-year-old woman who came to the Emergency Department with rare acute presentation of bilateral Krukenberg tumors, due to unilateral ovarian torsion. In this case report, we highlight the specific computed tomography (CT features of ovarian torsion and demonstrate the unique radiological findings on CT imaging. Metastasis to the ovary is not rare and 5 to 10% of all ovarian malignancies are metastatic. The stomach is the common primary site in most Krukenberg tumors (70%; an acute presentation of metastatic Krukenberg tumors with ovarian torsion is rare and not previously reported in radiology literature.
Physics of detecting torsion and placing limits on its effects
International Nuclear Information System (INIS)
Stoeger, W.R.
1985-01-01
The essential principles of torsion-detection physics are presented, and an evaluation is conducted of several conceivable types of experiments and observations for actually detecting torsion fields, reemphasizing also the evident impossibility of successfully searching for its manifestations among cosmological relics. In particular, a polarized body, with net intrinsic (fundamental-particle) spin, is essential for detecting a torsion field. One which possesses only orbital angular momentum - rotation - or an unpolarized intrinsic spin density will not feel torsion. The fundamental problem in searching for such fields is the extremely small basic unit of the coupling or interaction energy between the torsion field and spin. The best way of maximizing the total interaction energy is to increase the spin density of the source sigma-s and at the same time the spin number SD of the detector. 15 references
Peculiar torsion dynamical response of spider dragline silk
Liu, Dabiao; Yu, Longteng; He, Yuming; Peng, Kai; Liu, Jie; Guan, Juan; Dunstan, D. J.
2017-07-01
The torsional properties of spider dragline silks from Nephila edulis and Nephila pilipes spiders are investigated by using a torsion pendulum technique. A permanent torsional deformation is observed after even small torsional strain. This behaviour is quite different from that of the other materials tested here, i.e., carbon fiber, thin metallic wires, Kevlar fiber, and human hair. The spider dragline thus displays a strong energy dissipation upon the initial excitation (around 75% for small strains and more for a larger strain), which correspondingly reduces the amplitude of subsequent oscillations around the new equilibrium position. The variation of torsional stiffness in relaxation dynamics of spider draglines for different excitations is also determined. The experimental result is interpreted in the light of the hierarchical structure of dragline silk.
Stief, Thomas; Peikenkamp, Klaus
2015-01-01
Stress occurring at the feet while wearing footwear is often determined using pressure measurement systems. However, other forms of stress, such as bending, torsional and shear loadings, cannot be detected in shoes during day-to-day activities. Nevertheless, the detection of these types of stresses would be helpful for understanding the mechanical aspects of various kinds of hard and soft tissue injuries. Therefore, we describe the development of a new measuring device that allows the reliable determination of bending and torsional load at the foot in shoes. The system consists of a measuring insole and an analogue device with Bluetooth interface. The specific shape of the insole base layer, the positions of the strain gauges, and the interconnections between them have all been selected in such a way so as to isolate bending and torsional moment detections in the medial and lateral metatarsal region. The system was calibrated using a classical two-point test procedure. A single case study was executed to evaluate the new device for practical use. This application consisted of one subject wearing neutral shoes walking on a treadmill. The calibration results (coefficients of determination R(2) > 0.999) show that bending and torsional load can be reliably detected using the measurement system presented. In the single case study, alternating bending and torsional load can be detected during walking, and the shape of the detected bending moments can be confirmed by the measurements of Arndt et al. (J Biomech 35:621-8, 2002). Despite some limitations, the presented device allows for the reliable determination of bending and torsional stresses at the foot in shoes.
Elementary calculation of the shutdown delay of a pile
International Nuclear Information System (INIS)
Yvon, J.
1949-04-01
This study analyzes theoretically the progress of the shutdown of a nuclear pile (reactor) when a cadmium rod is introduced instantaneously. For simplification reasons, the environment of the pile is considered as homogenous and only thermal neutrons are considered (delayed neutrons are neglected). Calculation is made first for a plane configuration (plane vessel, plane multiplier without reflector, and plane multiplier with reflector), and then for a cylindrical configuration (multiplier without reflector, multiplier with infinitely thick reflector, finite cylindrical piles without reflector and with reflector). The self-sustain conditions are calculated for each case and the multiplication length and the shutdown delay are deduced. (J.S.)
Monitoring moisture content, temperature, and humidity in whole-tree pine chip piles
John Klepac; Dana Mitchell; Jason Thompson
2015-01-01
Two whole-tree chip piles were monitored for moisture content, temperature, and relative humidity from October 8th, 2010 to March 16th, 2011 at a location in south Alabama. Initial moisture content samples were collected immediately after chips were delivered to the study location on October 8th for Pile 1 and October 22nd for Pile 2. During pile construction, Lascar...
Estimating volume, biomass, and potential emissions of hand-piled fuels
Clinton S. Wright; Cameron S. Balog; Jeffrey W. Kelly
2009-01-01
Dimensions, volume, and biomass were measured for 121 hand-constructed piles composed primarily of coniferous (n = 63) and shrub/hardwood (n = 58) material at sites in Washington and California. Equations using pile dimensions, shape, and type allow users to accurately estimate the biomass of hand piles. Equations for estimating true pile volume from simple geometric...
Fatigue crack growth in 2017A-T4 alloy subjected to proportional bending with torsion
Directory of Open Access Journals (Sweden)
D. Rozumek
2017-10-01
Full Text Available The paper presents the results of tests on the fatigue crack growth for a constant moment amplitude under combined bending with torsion in the aluminium alloy AW-2017A-T4. The tests were performed under different values of the load ratio R. Plane specimens with stress concentrators in form of the external one-sided sharp notch were tested. A non-uniform fatigue cracks growth on both lateral surfaces of specimens was observed during experimental tests. Fatigue cracks were developing in the specimens in two stages; quarter-elliptic edge cracks were observed at the beginning, then evolving into through cracks
A Simple Algorithm for Analyzing a Piled Raft by Considering Stress Distribution
Directory of Open Access Journals (Sweden)
Alireza Saeedi Azizkandi
2014-12-01
Full Text Available Numerous techniques have been presented by different researchers to analyze piled raft. In order to analyze pile foundation, soil can be modeled as spring, continuous medium, or porous media. Pile can also be modeled as spring or continuous medium. This study includes three main stages: a short description of different types of analysis methods of pile foundation, writing a computer program based on the finite element method (FEM for analyzing piled raft foundation (in this program, foundation is modeled as a flexible plate, soil and pile are modeled by Winkler springs, and comparison of different concepts of pile group design.
Lundquist, Eugene E; Stowell, Elbridge Z
1942-01-01
An analysis is presented of the results of tests made by the Massachusetts Institute of Technology and by the National Advisory Committee for Aeronautics on an investigation of the strength of thin-walled circular and elliptic cylinders in pure bending and in combined torsion and bending. In each of the loading conditions, the bending moments were applied in the plane of the major axis of the ellipse.