Bartonicek, J.; Schoeckle, F.
In many cases the quality and integrity of a bolted joint depend on an exact prestressing level. This is essential with bolted flanged joints as well as with bolted pipe clamps, which are used in piping restraints. Without measuring the resulting prestress levels, common prestressing methods of flanged joints-as the use of torque spanners- might lead to insufficient prestressing levels and to a large scatterband in prestress values. The use of hydraulic tightening method is preferable. Using hydraulic tightening methods and specially developed measurement devices, controlled mounting of bolted flanged joints is easy. Control is provided during the entire tightening process, the resulting forces can be documented on printer output. Exact prestress levels can be controlled and applied to bolted pipe clamps with a new loading and measuring device. With this device the long term behaviour of the stress levels in the bolts of pipe clamps are measured successfully without dismounting the clamps. (orig.)
Full Text Available Bolted joint is widely used in mechanical and architectural structures, such as machine tools, industrial robots, transport machines, power plants, aviation stiffened plate, bridges, and steel towers. The bolt loosening induced by flight load and environment factor can cause joint failure leading to a disastrous accident. Hence, structural health monitoring is critical for the bolted joint detection. In order to realize a real-time and convenient monitoring and satisfy the requirement of advanced maintenance of the structure, this paper proposes an intelligent bolted joint failure monitoring approach using a developed decision fusion system integrated with Lamb wave propagation based actuator-sensor monitoring method. Firstly, the basic knowledge of decision fusion and classifier selection techniques is briefly introduced. Then, a developed decision fusion system is presented. Finally, three fusion algorithms, which consist of majority voting, Bayesian belief, and multiagent method, are adopted for comparison in a real-world monitoring experiment for the large aviation aluminum plate. Based on the results shown in the experiment, a big potential in real-time application is presented that the method can accurately and rapidly identify the bolt loosening by analyzing the acquired strain signal using proposed decision fusion system.
Yuansheng, Li; Guangpeng, Zhang; Zhen, Zhang; Ping, Wang
Bolt joints are common in machine tools and have a direct impact on the overall performance of the tools. Therefore, the understanding of bolt joint characteristics is essential for improving machine design and assembly. Firstly, According to the experimental data obtained from the experiment, the stiffness curve formula was fitted. Secondly, a finite element model of unit bolt joints such as bolt flange joints, bolt head joints, and thread joints was constructed, and lastly the stiffness parameters of joint surfaces were implemented in the model by the secondary development of ABAQUS. The finite element model of the bolt joint established by this method can simulate the contact state very well.
Luo, W. F.; Yu, L.
Compared with riveted and welded joints, bolted joints have advantages of easily dismantled, high load carrying and load-transferring capacity. However, bolted joints are also weaker components of assembled structures. Structural damage detection (SDD) on bolted joints is much required in the field of structural health monitoring (SHM). A new SDD method is proposed for damage identification of structures with bolted joints based on residual error of AR model in time series analysis. Firstly, a new data standardization process is defined to maintain the information of damage location. Then, a new structural damage feature sensitive to structural damage is developed based on the standard deviation of AR model residual errors. To verify the proposed method, a bolted joint structure is designed and fabricated in laboratory, connection damages of structures are simulated by loosening the bolted joints. The acceleration responses of structures with bolted joints under healthy and damage cases are acquired. Finally, the SDD is performed by traditional DSF and the new DSF. The illustrated results show that the proposed method is a hybrid tool for the bolted joint damage detection with the new damage-sensitive feature. In addition, some related issues will be discussed as well.
Liu, M. J.; Yu, S.; Zhao, Q. Y.
Fatigue performance of composite structure with imperfections is a challenging subject at present. Based on cohesive zone method and multi-continuum theory, delamination evolution response and fatigue life prediction of a 3D composite single-lap joint with a bolt-hole have been investigated through computer codes Abaqus and Fe-safe. Results from the comparison of a perfect composite bolted joint with another defect one indicates that a relatively small delamination damage around the bolt hole brings about significant degradation of local material performance. More notably, fatigue life of stress concentration region of composite bolted joints is highly sensitive to external loads, as an increase of 67% cyclic load amplitude leads to an decrease of 99.5% local fatigue life in this study. However, the numerical strategy for solving composite fatigue problems is meaningful to engineering works.
Full Text Available The effects of pretension in bolts on hysteretic response of timber joints exposed to a bending had been reported by the authors, but the cyclic tests were carried out at small displacement level which might not be applicable for earthquake-resistance design. In this study, similar cyclic tests but at large displacement levels were conducted. Beam to column timber joints with steel side plates were fabricated and continuously loaded until failure. At connection, the bolts were pretension in four different magnitudes: 0 kN, 5 kN, 10 kN and 15 kN. The results showed that frictional action between the steel side plates and wood member as a result of bolt pretensioning significantly increased the (frictional hysteretic damping and the equivalent viscous damping ratio. It is obvious from the test results that the pretension force in bolts has no influence on the maximum joint resistance but decreases the joint rotational deformation.
Zhu, Xiaolei; Liu, Yang; Wang, Yana; Lu, Xiaofeng; Zhu, Lingxue
The lattice core sandwich structures have drawn more attention for the integration of load capacity and multifunctional applications. However, the connection of carbon fibers reinforced polymer composite (CFRP) lattice core sandwich structure hinders its application. In this paper, a typical connection of two lattice core sandwich panels, named as corner joint or L-joint, was investigated by experiment and finite element method (FEM). The mechanical behavior and failure mode of the corner joints were discussed. The results showed that the main deformation pattern and failure mode of the lattice core sandwich bolted corner joints structure were the deformation of metal connector and indentation of the face sheet in the bolt holes. The metal connectors played an important role in bolted corner joints structure. In order to save the calculation resource, a continuum model of pyramid lattice core was used to replace the exact structure. The computation results were consistent with experiment, and the maximum error was 19%. The FEM demonstrated the deflection process of the bolted corner joints structure visually. So the simplified FEM can be used for further analysis of the bolted corner joints structure in engineering.
In this study, the behavior and the damage caused in the bolt joints in sandwich structures with laminates made of glass fiber and foam core is investigated. Many investigators ... been designed. The results of the tests show that the results of the finite element analysis and those of the experimental results are closely related.
Guo, Tao; Fan, Yougao; Gao, Feng; Gu, Shixin; Wang, Wei
Propulsion system is one of the important subsystems of satellite, and its performance directly affects the service life, attitude control and reliability of the satellite. The Paper analyzes the sealing principle of bolted joint ball head component of satellite propulsion system and discuss from the compatibility of hydrazine anhydrous and bolted joint ball head component, influence of ground environment on the sealing performance of bolted joint ball heads, and material failure caused by environment, showing that the sealing reliability of bolted joint ball head component is good and the influence of above three aspects on sealing of bolted joint ball head component can be ignored.
Ambarita H.; Fujiki H.; Daimaruya M.
This study is concerned with the development of a fracture criterion for the impact fracture of jointed steel plates of a bolted joint used in a car body. For the accurate prediction of crash characteristics of car bodies by computer-aided engineering (CAE), it is also necessary to examine the behavior and fracture of jointed steel plates subjected to impact loads. Although the actual impact fracture of jointed steel plates of a bolted joint used in cars is complicated, for simplifying the pr...
Matocha, K.; Wozniak, J.; Pochman, K.
Bolts made of type CHN35VT-VD stainless steel are being damaged due to stress corrosion cracking. In some cases, after some years of operation cracks appeared also in threaded holes of the primary collector flange due to transgranular stress corrosion cracking of type 08CH18N10T stainless steel. Stress corrosion cracking occurs when an alloy is exposed to a specific aggressive environment at a stress exceeding a critical value. The resistance of both steels to stress corrosion cracking in a high temperature environment was studied using slow strain rate tests of fatigue pre-cracked specimens. Dissolved oxygen or another strong oxidizer must be present to induce stress corrosion cracking of both steels in water environment at about 280 degC containing less than 15 ppm Cl - and 30 ppm SO 4 - . Measures are proposed to improve the reliability of primary collector bolted joints. (M.D.)
Mantelli, Marcia Barbosa Henriques; Basto, Jose Edson
The thermal resistance was experimentally determined of the bolted joints of the first Brazilian satellite (SCD 01). These joints, used to connect the satellite structural panels, are reproduced in an experimental apparatus, keeping, as much as possible, the actual dimensions and materials. A controlled amount of heat is forced to pass through the joint and the difference of temperature between the panels is measured. The tests are conducted in a vacuum chamber with liquid nitrogen cooled walls, that simulates the space environment. Experimental procedures are used to avoid much heat losses, which are carefully calculated. Important observations about the behavior of the joint thermal resistance with the variation of the mean temperature are made.
Satheeskumar, N.; Davison, J. B.
The robustness of steel joints in fire is important for steel building structures because of the need to prevent progressive collapse. Stainless steel is widely used in building construction mainly because of its corrosion resistance, but it also possesses improved fire resistance compared with conventional non-alloy, fine grain structural steels. Extensive research performed on the robustness of steel joints in fire has revealed that failure at elevated temperature may be controlled by bolt shear for fin plate and web cleat connections. Hence, this study focussed on the use of stainless steel in experimental tests conducted on fin plate and web cleat connections at high temperatures. In addition, this study investigated the use of a component-based model to predict connection performance at elevated temperature.
Li, Shichao; Gao, Hongli; Liu, Qi; Liu, Bokai
The dynamic characteristics of the bolted joints have a significant influence on the dynamic characteristics of the machine tool. Therefore, establishing a reasonable bolted joint dynamics model is helpful to improve the accuracy of machine tool dynamics model. Because the pressure distribution on the joint surface is uneven under the concentrated force of bolts, a dynamic modeling method based on the uneven pressure distribution of the joint surface is presented in this paper to improve the dynamic modeling accuracy of the machine tool. The analytic formulas between the normal, tangential stiffness per unit area and the surface pressure on the joint surface can be deduced based on the Hertz contact theory, and the pressure distribution on the joint surface can be obtained by the finite element software. Futhermore, the normal and tangential stiffness distribution on the joint surface can be obtained by the analytic formula and the pressure distribution on the joint surface, and assigning it into the finite element model of the joint. Qualitatively compared the theoretical mode shapes and the experimental mode shapes, as well as quantitatively compared the theoretical modal frequencies and the experimental modal frequencies. The comparison results show that the relative error between the first four-order theoretical modal frequencies and the first four-order experimental modal frequencies is 0.2% to 4.2%. Besides, the first four-order theoretical mode shapes and the first four-order experimental mode shapes are similar and one-to-one correspondence. Therefore, the validity of the theoretical model is verified. The dynamic modeling method proposed in this paper can provide a theoretical basis for the accurate dynamic modeling of the bolted joint in machine tools.
Abid, Muhammad; Khan, Ayesha; Nash, David Hugh; Hussain, Masroor; Wajid, Hafiz Abdul
Achieving a proper preload in the bolts of a gasketed bolted flanged pipe joint during joint assembly is considered important for its optimized performance. This paper presents results of detailed non-linear finite element analysis of an optimized bolt tightening strategy of different joint sizes for achieving proper preload close to the target stress values. Industrial guidelines are considered for applying recommended target stress values with TCM (torque control method) and SCM (stretch control method) using a customized optimization algorithm. Different joint components performance is observed and discussed in detail.
Zabihpoor, M.; Moslemian, Ramin; Afshin, M.
This study represents an effort to predict the bearing strength, failure modes, and failure load of bolted joints in foam-core sandwich composites. The studied joints have been used in a light full composite airplane. By using solid laminates, a new design for the joint zone is developed. These s......This study represents an effort to predict the bearing strength, failure modes, and failure load of bolted joints in foam-core sandwich composites. The studied joints have been used in a light full composite airplane. By using solid laminates, a new design for the joint zone is developed...
Peter James Moss
This study reviewed the literature on experimental and analytical research for the connection of wood members using multiple laterally loaded bolts. From this, the influence of geometric factors were ascertained, such as staggered and aligned fasteners, optimum fastener configurations, row factors and length-to-diameter bolt ratios, spacing, end and edge distances, and...
Li, Linjie; Qu, Junli; Liu, Xiangdong
A three-dimensional progressive damage model was developed in ANSYS to predict the damage accumulation of single bolted joint in composite laminates under in-plane tensile loading. First, we describe the formulation and algorithm of this model. Second, we calculate the failure loads of the joint in fibre reinforced epoxy laminated composite plates and compare it with the experiment results, which validates that our model can appropriately simulate the ultimate tensile strength of the joints and the whole process of failure of structure. Finally, this model is applied to study the failure process of the light-weight composite material (USN125). The study also has a great potential to provide a strong basis for bolted joints design in composite Laminates as well as a simple tool for comparing different laminate geometries and bolt arrangements.
Baiburin, A. Kh; Semenov, K. O.
This paper presents an analysis of semi-rigid effects of bolted joints occurring due to clearance holes and manufacturing tolerances at temporary fixing and the exploitation stages. The manufacturing requirements of SP 53-101-98 ‘Production and Quality Control of Steel Structures’ and GOST 23118-2012 ‘Building Steel Structures. General Specifications’ are used for calculations. Friction-grip joints with high-strength bolts are considered as well as joints with ordinary structural bolts. Different permissible assembling technologies are reviewed to account a non-linear behaviour of the joint at temporary fixing and during the operational stage. The recommendations were developed for the scheduling of mounting works which can provide convergence between the design of a whole building and the consequential calculations of mounting schemes.
Rodabaugh, E.C.; Moore, S.E.
The ASME Boiler and Pressure Vessel Code, Section VIII, Division 1, gives rules which are subdivided into ''Part A'' and ''Part B''. Part A covers flanged joints where contact between flanges occurs through a gasket located inside the bolt holes. Part B covers flanged joints with contact outside the bolt holes. This report (a) summarizes the theory for Part B flanged joints, (b) presents examples which show the significant differences between Part A flanged joints and Part B flanged joints, (c) presents the available test data relevant to the characteristics of Part B flanged joints, (d) gives listings of two computer programs which can be used to evaluate the characteristics of Part B flanged joints, and (e) gives recommendations for Code revisions and other aspects of Part B flanged-joint design
Oregui Echeverria-Berreyarza, M.; Li, S.; Li, Z.; Carroll, R; Dollevoet, R.P.B.J.
Rail joints are a weak component in railway tracks because of the large impact and wheel-rail contact forces. Every train passage contributes to the deterioration of rail joints, causing visible (e.g. battered rails) and invisible (e.g. loose bolts) damages. The invisible damage cannot be detected
Full Text Available Online and offline monitoring of composite bolted joints under tensile load were investigated using piezoelectric transducers. The relationships between Lamb wave signals, pre-tightening force, the applied tensile load, as well as the failure modes were investigated. Results indicated that S0/A0 wave amplitudes decrease with the increasing of load. Relationships between damage features and S0/A0 mode were built based on the finite element (FE simulation and experimental results. The possibility of application of Lamb wave-based structure health monitoring in bolted joint-like composite structures was thus achieved.
Yang, Bin; Xuan, Fu-Zhen; Xiang, Yanxun; Li, Dan; Zhu, Wujun; Tang, Xiaojun; Xu, Jichao; Yang, Kang; Luo, Chengqiang
Online and offline monitoring of composite bolted joints under tensile load were investigated using piezoelectric transducers. The relationships between Lamb wave signals, pre-tightening force, the applied tensile load, as well as the failure modes were investigated. Results indicated that S0/A0 wave amplitudes decrease with the increasing of load. Relationships between damage features and S0/A0 mode were built based on the finite element (FE) simulation and experimental results. The possibility of application of Lamb wave-based structure health monitoring in bolted joint-like composite structures was thus achieved. PMID:28773014
Full Text Available Improvement of cyclic or dynamic performance of timber connections has been intensively conducted since the overall response of wooden structures is merely a function of joint performance. For a bolted joint, filling the lead-hole clearance with epoxy resin or gluing high embedding-strength materials at the interface of the individual timber member are probably the most common methods. This study presents cyclic test results of moment-resisting joints with a combination of bolts and nails. The nails were placed closer to the joint centroid than the bolts, acting as additional fasteners and were expected to improve the seismic performance of the joints. Static-cyclic test results confirmed the increase of joint stiffness and moment resistance due to the additional nails. The nails contribute to the increase of hysteretic damping significantly though pinching behavior or narrowing the hysteresis loops close to zero rotation points was still observed. The results indicated that contribution of nails or bolts on moment resistance and hysteretic damping can be superimposed.
Full Text Available Failure in timber structures occurs mainly in crucial points such as joints areas. Therefore, the idea of using composite sheets in timber joints has been intro-duced as a method in order to increase the strength and ductility behaviour of timber joints. This research aims to study the behaviour of bolted joints in poplar and pine woods, which are reinforced by two types of GFRP sheets. A single shear bolted joint consisted of 3 timber members whose length and width were 30 cm in length and 5 cm in width. The thickness of each member was 4 cm for internal part and 2 cm for external part. The employed steel bolt was 10 cm in length and 1 cm in diameter. In this respect, one layer of GFRP sheet was used to be bonded to timber members by using epoxy resin and left between the clamps for 24 hours. They were then kept at room temperature for three weeks. Also the effect of adding a wood veneer on the reinforced joints was investigated. The tensile strength of the reinforced and control samples (un-reinforced joints was measured according to ASTM D5652-92 standard. The results show that the reinforced samples have higher tensile strength compared to that of reinforced joints, although it is not statistically signifcant. Also, two types of sheets infuence the joint behaviour as the reinforced joints display more ductility behaviour.
Li, Xuwei; Aziz, Naj; Mirzaghorbanali, Ali; Nemcik, Jan
This paper experimentally compares the shear behavior of fiber glass (FG) bolt, rock bolt (steel rebar bolt) and cable bolt for the bolt contribution to bolted concrete surface shear strength, and bolt failure mode. Two double shear apparatuses of different size were used for the study. The tensile strength, the shear strength and the deformation modulus of bolt control the shear behavior of a sheared bolted joint. Since the strength and deformation modulus of FG bolt, rock bolt and cable bolt obtained from uniaxial tensile tests are different, their shear behavior in reinforcing joints is accordingly different. Test results showed that the shear stiffness of FG bolted joints decreased gradually from the beginning to end, while the shear stiffness of joints reinforced by rock bolt and cable bolt decreased bi-linearly, which is clearly consistent with their tensile deformation modulus. The bolted joint shear stiffness was highly influenced by bolt pretension in the high stiffness stage for both rock bolt and cable bolt, but not in the low stiffness stage. The rock bolt contribution to joint shear strength standardised by the bolt tensile strength was the largest, followed by cable bolts, then FG bolts. Both the rock bolts and cable bolts tended to fail in tension, while FG bolts in shear due to their low shear strength and constant deformation modulus.
Wu, Bo; Ou, Yunlong
Shield tunnels have been widely used in city metros all over the world. During the long-term period of the metro operation, the joints of shield tunnel’s neighboring segments may degrade due to some environmental factors, leading to the increasing of the joint opening and some resulting adverse consequences. In this paper, a temporary strengthening method by using shape memory alloy (SMA) bolts is proposed and experimentally studied for the joints of neighboring segments, and a revised electric heating method which suits with the strengthening method is presented and experimentally validated for the SMA bolts. The purpose of the proposed temporary strengthening method is to create favorable conditions for the following permanent strengthening. Test results show that: (a) for the joints of shield tunnel’s neighboring segments, the strengthening method can effectively reduce the joint opening, joint deflection, concrete strain in joint’s compression zone, and strain of joint’s steel bolts; (b) the revised electric heating method can be used to heat the SMA rod to a temperature higher than the SMA’s austenite finish temperature quickly, and the average heating rate related to Type 2 inner resistance element is larger than that related to Type 1 inner resistance element; and (c) the reduction percentages of the joint opening increment, joint deflection, concrete strain in joint’s compression zone, and strain of joint’s steel bolts for Specimen I are all larger than those for Specimen II, implying that the less the joint opening is, the more significant the strengthening effect is. (paper)
Full Text Available Gasketed bolted flange joints are the most critical components in pipelines for their sealing and strength under operating conditions. Most of the work available in literature is under static loading, whereas in industry, cyclic loads are applied due to the vibrating machinery such as motors, pumps, sloshing in offshore applications and in the ships etc. In this study a three dimensional finite element analysis of a gasketed joint is carried out using a spiral wound gasket under bolt up and dynamic operating conditions (internal pressure, axial and bending singly and in combination. The cyclic axial loads are concluded relatively more challenging for both the sealing and strength of the joint. Higher magnitudes of loads and frequencies are also observed more challenging to the joints performance.
Cao Lei; Song Yuntao
The first wall in the Experimental Advanced Superconducting Tokamak (EAST) used graphite tiles to withstand high thermal energy. The graphite tiles are mounted on the heat sink using screw bolts which have been preloaded to produce a clamp force. The clamp force is very important to keep the graphite tiles tightly on the surface of the heat sink so that the heat flux crosses this contacting surface in a small thermal resistor. Without the clamp force, the small gap between the graphite tiles and the heat sink will make it impossible for thermal power to be carried away by cooling water. Some bolts may even fall off with the loss of clamp force. From the mathematical models, the loss process of the clamp force has been studied. Research results explain how the different thermal expansions of three members of the screw joint makes the clamp force decrease to zero under temperature rise and external force, and how the stiffness affects the relation between the clamp force and temperature. The research also gives the critical temperature at which the clamp force can remain above zero. Analysis results indicate that the current screw joints are almost destined to lose their clamp force during the running time of EAST, so the bolt joints should be redesigned in order to improve its reliability.
Tesfa, B.; Horler, G.; Thobiani, F. Al; Gu, F.; Ball, A. D.
Many industrial structures associated with railway infrastructures rely on a large number of bolted joint connections to ensure safe and reliable operation of the track and trackside furniture. Significant sums of money are spent annually to repair the damage caused by bolt failures and to maintain the integrity of bolted structures. In the UK, Network Rail (the organization responsible for rail network maintenance and safety) conducts corrective and preventive maintenance manually on 26,000 sets of points (each having approximately 30 bolted joints per set), in order to ensure operational success and safety for the travelling public. Such manual maintenance is costly, disruptive, unreliable and prone to human error. The aim of this work is to provide a means of automatically measuring the clamping force of each individual bolted joint, by means of an instrumented washer. This paper describes the development of a sensor means to be used in the washer, which satisfies the following criteria. Sense changes in the clamping force of the joint and report this fact. Provide compatibility with the large dynamic range of clamping force. Satisfy the limitations in terms of physical size. Provide the means to electronically interface with the washer. Provide a means of powering the washer in situ. Provide a solution at an acceptable cost. Specifically the paper focuses on requirements 1, 2 and 3 and presents the results that support further development of the proposed design and the realization of a pre-prototype system. In the paper, various options for the force sensing element (strain gage, capacitor, piezo-resistive) have been compared, using design optimization techniques. As a result of the evaluation, piezo-resistive sensors in concert with a proprietary force attenuation method, have been found to offer the best performance and cost trade-off The performance of the novel clamping force sensor has been evaluated experimentally and the results show that a smart washer
interracial locations between adjacent plies. Incorporating these into an interlaminar failure criterion, the joint load corresponding to the earliest...procedure introduces inaccuracies that have been acknowledged and discussed in the literature. Nevertheless, SAMCJ adopts this procedure for lack of a
In applying the glulam timber to the large-sized structures, the new types of connections have been developed. In presence, there are a few joint systems using steel plates and bolts. However, those systems are not always adequately satisfied with durability. Therefore, the new joint system by prestressing was developed. In Nagano prefecture, the timber-concrete composite bridge was provided as the standard design of timber bridges, and the joint system is by prestressing. In case of concrete girder, work of prestress decrease by elastic strain, creep, and etc. However, timber-concrete composite girder is not cleared numerically. In this study, we discussed the effective prestress on timber-concrete composite girder based on time-dependent of prestress checked in existing bridge, and we suggest the evaluation method of it.
This report contains a theoretical discussion of the load distribution in bolted or riveted joints in light-alloy structures which is applicable not only for loads below the limit of proportionality but also for loads above this limit. The theory is developed for double and single shear joints. The methods given are illustrated by numerical examples and the values assumed for the bolt (or rivet) stiffnesses are based partly on theory and partly on known experimental values. It is shown that the load distribution does not vary greatly with the bolt (or rivet) stiffnesses and that for design purposes it is usually sufficient to know their order of magnitude. The theory may also be directly used for spot-welded structures and, with small modifications, for seam-welded structures, The computational work involved in the methods described is simple and may be completed in a reasonable time for most practical problems. A summary of earlier theoretical and experimental investigations on the subject is included in the report.
Kradinov, V.; Madenci, E.; Ambur, D. R.
Although two-dimensional methods provide accurate predictions of contact stresses and bolt load distribution in bolted composite joints with multiple bolts, they fail to capture the effect of thickness on the strength prediction. Typically, the plies close to the interface of laminates are expected to be the most highly loaded, due to bolt deformation, and they are usually the first to fail. This study presents an analysis method to account for the variation of stresses in the thickness direction by augmenting a two-dimensional analysis with a one-dimensional through the thickness analysis. The two-dimensional in-plane solution method based on the combined complex potential and variational formulation satisfies the equilibrium equations exactly, and satisfies the boundary conditions and constraints by minimizing the total potential. Under general loading conditions, this method addresses multiple bolt configurations without requiring symmetry conditions while accounting for the contact phenomenon and the interaction among the bolts explicitly. The through-the-thickness analysis is based on the model utilizing a beam on an elastic foundation. The bolt, represented as a short beam while accounting for bending and shear deformations, rests on springs, where the spring coefficients represent the resistance of the composite laminate to bolt deformation. The combined in-plane and through-the-thickness analysis produces the bolt/hole displacement in the thickness direction, as well as the stress state in each ply. The initial ply failure predicted by applying the average stress criterion is followed by a simple progressive failure. Application of the model is demonstrated by considering single- and double-lap joints of metal plates bolted to composite laminates.
Kulkarni, Ravindra B.; Vaghe, Vishal M.
Cold-formed structural members are being used more widely in routine structural design as the world steel industry moves from the production of hot-rolled section and plate to coil and strip, often with galvanized and/or painted coatings. Steel in this form is more easily delivered from the steel mill to the manufacturing plant where it is usually cold-rolled into open and closed section members. In the present experimental study, the use of packing plate at the joints in cold-formed channel sections may increase the load carrying capacity and also reduce the buckling of unconnected cold form channel steel plate at joints. The present study focuses on examining the experimental investigation to use mild steel as a packing plate with cold-formed channel sections by bolted connection at the joints and the connection subjected to axial tension. Series of tests are carried out with increase in the thickness of packing plate and results are observed and analyzed. Total Twelve experimental tests have been carried out on cold-formed channel tension members fastened with single as well as three numbers of bolts at the connection and from the observations the strength of the joint is increased by increasing the various thicknesses of packing plates and also the buckling of unconnected leg of channel specimen is reduced. It is analyzed by plotting the entire load versus elongation path, so that the behavior of the connection is examined.
Full Text Available The performed tests intended to establish the necessary conditions for surfaces of the assemblage elements in contact with the KB, so as, by connecting them using the HSFG (High Strength Friction Grip bolts, to ensure the necessary frictional resistance. The tests have performed using 2.5mm thickness KB250 thin – walled profiles. This minimum thickness is often used for structural elements in this constructive system. The KONTIBEAM system is primarily made of two galvanized sheet profiles so denominated as “KB”, which are joined by means of steel sheets, (usually of 10 mm thickness, placed in – between them. Connecting this assembly (KB’s and connectors is done by using M20 bolts put in Ø 22 holes, which work in friction with two contact planes. The tested joints are connected by means of 8.8 class HSFG bolts. The connecting elements for tested KB’s have been manufactured with two types of prepared surfaces: (i rough (sandblasted and (ii covered with a zincamid film. The main conclusions of tests are that the bearing capacity of connections with sandblasted surface joining elements observes the norms while the bearing capacity of connections with painted – surface joining elements does not observes the norms.
Wang, Yishou; Qing, Xinlin; Dong, Liang; Banerjee, Sourav
Advanced fiber reinforced composite materials are becoming the main structural materials of next generation of aircraft because of their high strength and stiffness to weight ratios, and excellent designability. As key components of large composite structures, joints play important roles to ensure the integrity of the composite structures. However, it is very difficult to analyze the strength and failure modes of composite joints due to their complex nonlinear coupling factors. Therefore, there is a need to monitor, diagnose, evaluate and predict the structure state of composite joints. This paper proposes a multi-field coupled sensing network for health monitoring of composite bolted joints. Major work of this paper includes: 1) The concept of multifunctional sensor layer integrated with eddy current sensors, Rogowski coil and arrayed piezoelectric sensors; 2) Development of the process for integrating the eddy current sensor foil, Rogowski coil and piezoelectric sensor array in multifunctional sensor layer; 3) A new concept of smart composite joint with multifunctional sensing capability. The challenges for building such a structural state sensing system and some solutions to address the challenges are also discussed in the study.
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AUTHOR|(CDS)2225945; Dassa, Luca; Welo, Torgeir
This thesis investigates how finite element analysis (FEA) can be used to simplify and improve analysis of bolted joints according to the guideline VDI 2230. Some aspects of how FEA can be applied to aid design and verification of bolted joints are given in the guideline, but not in a streamlined way that makes it simple and efficient to apply. The scope of this thesis is to clarify how FEA and VDI 2230 can be combined in analysis of bolted joints, and to present a streamlined workflow. The goal is to lower the threshold for carrying out such combined analysis. The resulting benefits are improved analysis validity and quality, and improved analysis efficiency. A case from the engineering department at CERN, where FEA has been used in analysis of bolted joints is used as basis to identify challenges in combining FEA and VDI 2230. This illustrates the need for a streamlined analysis strategy and well described workflow. The case in question is the Helium vessel (pressure vessel) for the DQW Crab Cavities, whi...
Park, Gyuhae [Los Alamos National Laboratory; Farrar, Charles R [Los Alamos National Laboratory; Park, Chan - Yik [ADD; Jun, Seung - Moon [ADD
This paper is a report of an initial investigation into tracking and monitoring the integrity of bolted joints using piezoelectric active-sensors. The target application of this study is a fitting lug assembly of unmanned aerial vehicles (UAVs), where a composite wing is mounted to a UAV fuselage. The SHM methods deployed in this study are impedance-based SHM techniques, time-series analysis, and high-frequency response functions measured by piezoelectric active-sensors. Different types of simulated damage are introduced into the structure, and the capability of each technique is examined and compared. Additional considerations encountered in this initial investigation are made to guide further thorough research required for the successful field deployment of this technology.
Full Text Available Many metal parts in various applications are being replaced by plastic parts. There are several reasons for that depending on actual application - minimize part cost, enhance corrosion resistance, integrating more components into one part etc. Most important steps of metal to plastic conversion are material selection and design of plastic part. Plastic part has to withstand the same load as metal part. To fulfill this requirement fiber reinforced engineering plastics are often used. Also it is convenient to substitute heavy wall sections with ribbed structure to increase load-carrying ability of part and decrease cycle time, eliminate voids, sink marks etc. Mechanical properties of such part could be highly affected by fiber orientation. Results of fiber orientation from injection molding filling analysis can be used in stress analysis for better prediction of part response to mechanical load. Such coupled analysis is performed here in this case study on bolted flange joint.
Gessner, Robby, E-mail: firstname.lastname@example.org [Karlsruhe Institute of Technology, Institute for Applied Materials, P.O. Box 3640, D-76021 Karlsruhe (Germany); Aiello, Gaetano; Grossetti, Giovanni; Meier, Andreas [Karlsruhe Institute of Technology, Institute for Applied Materials, P.O. Box 3640, D-76021 Karlsruhe (Germany); Ronden, Dennis [DIFFER – Dutch Institute for Fundamental Energy Physics, P.O. Box 1207, NL-3430 BE Nieuwegein (Netherlands); Spaeh, Peter; Scherer, Theo; Schreck, Sabine; Strauss, Dirk; Vaccaro, Alessandro [Karlsruhe Institute of Technology, Institute for Applied Materials, P.O. Box 3640, D-76021 Karlsruhe (Germany)
Highlights: ► The BSM of the ECH Launcher is attached to the Launcher Main Frame by a bolted joint. ► The bolts were designed as “captive” in order to avoid their accidental removal from the joint. ► The bolted flange connection using two sets of 15 captive bolts (M22 × 2) placed along the sides. ► The captive bolt design is based on a concept that uses a dedicated spring ring, a standard spiral spring and a tensioning screw with two threads to secure the bolts in a form-locking stop. -- Abstract: The final design of the structural system for the ITER EC H and CD upper launcher is in progress. Many design features of the preliminary design are under revision with the aim to achieve the built-to-print-status. This paper deals with design and analysis of a bolted joint for the Blanket Shield Module with special perspective on Remote Handling capability. The BSM of the ECH Launcher is attached to the Launcher Main Frame by a bolted joint conceived so that in the Hot Cell Facility, RH maintenance can be performed on internal components. The joint must be capable to resist very high Electro-Magnetic loads from disruptions, while it has to sustain substantial thermal cycling during operation. Thus the need for a rigid and reliable design is essential. Beside the set of pre-stressed bolts the flanges were therefore equipped with additional shear keys to divert radial moments away from the bolts. Main focus of the work performed was the mechanical design of the joint and the assessment of the structural integrity with respect to the loads applied and its capability for maintenance by RH procedures. To fulfill a major aspect of the RH requirements, the bolts were designed as “captive” in order to avoid their accidental removal from the joint. The captive bolt design is based on a concept that uses a dedicated spring ring, a standard spiral spring and a tensioning screw with two threads to secure the bolts in a form-locking stop. The final approval phase of
An investigation of bolting practices specific to the nuclear industry was performed. The report covered a large spectrum of topics e.g., bolts embedded in concrete, specifications, inspection of bolting, both at receipt and inservice. Plots of preload versus yield strength for different bolting materials in different environments are presented as well as information relative to the stress corrosion cracking resistance of the more recent reactor internals bolting materials A286 and Inconel X-750. Part of the report contains input by Standard Pressed Steel Inc. (a bolting consultant) relative to bolting standards, cottering methods and potential areas for bolting improvement
Full Text Available This work aims to investigate the fretting fatigue life and failure mode of steel Q235B plates in single-lap bolted joints. Ten specimens were prepared and tested to fit the S-N curve. SEM (scanning electron microscope was then employed to observe fatigue crack surfaces and identify crack initiation, crack propagation, and transient fracture zones. Moreover, a FEM model was established to simulate the stress and displacement fields. The normal contact stress, tangential contact stress, and relative slipping displacement at the critical fretting zone were used to calculate FFD values and assess fretting fatigue crack initiation sites, which were in good agreement with SEM observations. Experimental results confirmed the fretting fatigue failure mode for these specimens. It was found that the crack initiation resulted from wear regions at the contact surfaces between plates, and fretting fatigue cracks occurred at a certain distance away from hole edges. The proposed FFD-N relationship is an alternative approach to evaluate fretting fatigue life of steel plates in bolted joints.
Koyankin Aleksandr Aleksandrovich
Full Text Available Precast-monolithic construction is becoming an increasingly popular form of housing. The wide distribution of this type of construction is explained by the possibility to successfully combine the advantages of precast and monolithic construction, at the same time reducing their disadvantages. Though there is a significant lack of data, including experimental data, for objective assessment of the stress-strain state of precast-monolithic floor structures. In order to investigate the structural reliability of the bolt joint of a bearer with a column in a precast-monolithic building a series of experimental investigations were carried out in the laboratory of testing the building structures of the Siberian Federal University.One of the main conclusions is that the bolt joint of a bearer with a column is characterized by sufficient rigidity, crack resistance and bearing capacity. The results of the given work have proved the data obtained in previously conducted investigations on a fragment of a precast-monolithic ceiling.
Liu, Wenpeng; Rostami, Jamal; Elsworth, Derek; Ray, Asok
Roof bolts are the dominant method of ground support in mining and tunneling applications, and the concept of using drilling parameters from the bolter for ground characterization has been studied for a few decades. This refers to the use of drilling data to identify geological features in the ground including joints and voids, as well as rock classification. Rock mass properties, including distribution of joints/voids and strengths of rock layers, are critical factors for proper design of ground support to avoid instability. The goal of this research was to improve the capability and sensitivity of joint detection programs based on the updated pattern recognition algorithms in sensing joints with smaller than 3.175 mm (0.125 in.) aperture while reducing the number of false alarms, and discriminating rock layers with different strengths. A set of concrete blocks with different strengths were used to simulate various rock layers, where the gap between the blocks would represent the joints in laboratory tests. Data obtained from drilling through these blocks were analyzed to improve the reliability and precision of joint detection systems. While drilling parameters can be used to detect the gaps, due to low accuracy of the results, new composite indices have been introduced and used in the analysis to improve the detection rates. This paper briefly discusses ongoing research on joint detection by using drilling parameters collected from a roof bolter in a controlled environment. The performances of the new algorithms for joint detection are also examined by comparing their ability to identify existing joints and reducing false alarms.
Full Text Available A parametric study of the stress distribution in the composite plates is undertaken to show the effect of different lay-ups. Full 3-D elastic properties are required in the modelling. These properties are calculated using equations taken from the literature and derivation from simple Classical Laminate Plate Theory (CLPT. In previous experimental work, it was shown that tensile failure involved the development of a damage zone at the edge of the hole. In a double-lap joint, it is assumed that uniform stresses are exhibited throughout the plate thickness. Different lay-ups system give different tangential stress distributions and insignificant variation in the radial stress distribution along the hole boundary.
In tightening critical structural members such as pressure vessels of nuclear reactors and chemical plants and important parts of diesel engines, a hydraulic tensioner is widely used because of its high accuracy in controlling clamping force. The ratio of the desired clamping force to initial tension, which is termed the effective tensile coefficient, is the most important factor to be predicted in the actual operation of given joint configurations. It is reported, however, that a certain amount of scatter in clamping force cannot be avoided. In this paper, an elementary approach to analyze the tightening process is proposed using spring elements, where the effects of incorrect geometry at contact surface on the coefficient are taken into account. The influences of pitch error and flatness deviation at the nut-loaded surface are discussed. Finally, a simple equation for estimating the coefficient is presented, where the major factors influencing scatter in clamping force are considered. (author)
Mok, G.C.; Fischer, L.E.; Hsu, S.T.
This report specifies the requirements and criteria for stress analysis of closure bolts for shipping casks containing nuclear spent fuels or high level radioactive materials. The specification is based on existing information conceming the structural behavior, analysis, and design of bolted joints. The approach taken was to extend the ASME Boiler and Pressure Vessel Code requirements and criteria for bolting analysis of nuclear piping and pressure vessels to include the appropriate design and load characteristics of the shipping cask. The characteristics considered are large, flat, closure lids with metal-to-metal contact within the bolted joint; significant temperature and impact loads; and possible prying and bending effects. Specific formulas and procedures developed apply to the bolt stress analysis of a circular, flat, bolted closure. The report also includes critical load cases and desirable design practices for the bolted closure, an in-depth review of the structural behavior of bolted joints, and a comprehensive bibliography of current information on bolted joints
Building multi-simple span bridges using precast prestressed concrete girders is an easy construction. However, the existence of : expansion joints often leads to a host of problems in their vicinity due to drainage leaks. Furthermore, debris accumul...
Full Text Available A new method was developed to apply pull-and-shear loads to the bolt specimen in order to evaluate the anchorage performance of the rebar bolt and the D-Bolt. In the tests, five displacing angles (0°, 20°, 40°, 60°, and 90°, two joint gaps (0 mm and 30 mm, and three kinds of host rock materials (weak concrete, strong concrete, and concrete-granite were considered, and stress–strain measurements were conducted. Results show that the ultimate loads of both the D-Bolt and the rebar bolt remained constant with any displacing angles. The ultimate displacement of the D-Bolt changed from 140 mm at the 0° displacing angle (pure pull to approximately 70 mm at a displacing angle greater than 40°. The displacement capacity of the D-Bolt is approximately 3.5 times that of the rebar bolt under pure pull and 50% higher than that of the rebar bolt under pure shear. The compressive stress exists at 50 mm from the bolt head, and the maximum bending moment value rises with the increasing displacing angle. The rebar bolt mobilises greater applied load than the D-Bolt when subjected to the maximum bending. The yielding length (at 0° of the D-Bolt is longer than that of the rebar bolt. The displacement capacity of the bolts increased with the joint gap. The bolt subjected to joint gap effect yields more quickly with greater bending moment and smaller applied load. The displacement capacities of the D-Bolt and the rebar bolt are greater in the weak host rock than that in the hard host rock. In pure shear condition, the ultimate load of the bolts slightly decreases in the hard rock. The yielding speed in the hard rock is higher than that in the weak rock.
Sampling Interval 1 sec Sample Load -lg 38 measuring prot>« alumina discs aluminium tin V- incooel tray sample support Figure 2.13 - TMA Typical...OcutU OuMM *«»j» rj Bnju, .> umt I0VE itrf-uerr I15*1 Own* Bang, I inmw4 wan HOI 3 Owl* Ouvtv 8Mgt ! mHml ftn na JIM Bug*. 4 «tem« stamps 4...the bolts are being tightened. There is also a log button located on this screen. It allows the user to log a single data point, with a time stamp
Abspoel, R.; Dubina, D.; Ungureanu, V.
In a material economy driven plate girder design, the lever arm between the flanges will increase. This leads to higher stiffness and bending moment resistance, but also to an in-crease of the web slenderness. This means that high strength steels can be used leading to a large reduction of the steel
Spliced girder technology continues to attract : attention due to its versatility over traditional : prestressed concrete highway bridge construction. : By joining multiple precast concrete girders using : post-tensioning, spliced girder technology :...
Sherrit, Stewart; Badescu, Mircea; Bar-Cohen, Yoseph; Barengoltz, Jack; Heckman, Vanessa
A proposed family of devices for inducing fatigue in bolts in order to break the bolts would incorporate piezoelectric actuators into resonant fixtures as in ultrasonic/ sonic drills/corers and similar devices described in numerous prior NASA Tech Briefs articles. These devices were originally intended primarily for use as safer, more-reliable, more-versatile alternatives to explosive bolts heretofore used to fasten spacecraft structures that must subsequently be separated from each other quickly on command during flight. On Earth, these devices could be used for accelerated fatigue testing of bolts. Fatigue theory suggests that a bolt subjected to both a constant-amplitude dynamic (that is, oscillatory) stress and a static tensile stress below the ultimate strength of the bolt material will fail faster than will a bolt subjected to only the dynamic stress. This suggestion would be applied in a device of the proposed type. The device would be designed so that the device and the bolt to be fatigue-tested or broken would be integral parts of an assembly (see figure). The static tension in the tightened bolt would apply not only the clamping force to hold the joined structures (if any) together but also the compression necessary for proper operation of the piezoelectric actuators as parts of a resonant structural assembly. The constant-amplitude dynamic stress would be applied to the bolt by driving the piezoelectric actuators with a sinusoidal voltage at the resonance frequency of longitudinal vibration of the assembly. The amplitude of the excitation would be made large enough so that the vibration would induce fatigue in the bolt within an acceptably short time. In the spacecraft applications or in similar terrestrial structural-separation applications, devices of the proposed type would offer several advantages over explosive bolts: Unlike explosive bolts, the proposed devices would be reusable, could be tested before final use, and would not be subject to
Pedersen, Niels Leergaard
and the tensile force in the bolt. In the literature and also in standards,different models are presented for this important non-linear response. In the present paper, a simplified expression for the non-linear force response is presented based on finite element calculations using contact analysis. The L......In wind turbine towers, the preferred design is circular tubes that are connected by a bolted flange joint. The design is typically that of an L-flange resulting in an eccentrically loaded bolted connection. The eccentricity results in a non-linear relationship between external load on the tower......-flange connection is in essence a bad design because it leads to a non-optimal ratio between external force and bolt force. Furthermore,bolt bending results in an even higher bolt stress resulting in a reduction of strength. The present paper presents simple modifications of the L-flange design that considerably...
Larsen, Curtis E.; Wilson, Tim R.; Elliott, Kenny B.; Raju, Ivatury S.; McManamen, John
Following STS-107, the External Tank (ET) Project implemented corrective actions and configuration changes at the ET bipod fitting. Among the corrective actions, the existing bolt lock wire which provided resistance to potential bolt rotation was removed. The lock wire removal was because of concerns with creating voids during foam application and potential for lock wire to become debris. The bolts had been previously lubricated to facilitate assembly but, because of elimination of the lock wire, the ET Project wanted to enable the locking feature of the insert. Thus, the lubrication was removed from bolt threads and instead applied to the washer under the bolt head. Lubrication is necessary to maximize joint pre-load while remaining within the bolt torque specification. The locking feature is implemented by thread crimping in at four places in the insert. As the bolt is torqued into the insert the bolt threads its way past the crimped parts of the insert. This provides the locking of the bolt, as torque is required to loosen the joint after clamping.
Ammar Yasir Ali
Full Text Available In this paper, the behavior of spliced continuous reinforced concrete girders was experimentally investigated. The main objective was to examine the contribution of the carbon fiber reinforced polymer (CFRP laminates in strengthening the spliced continuous reinforced concrete girders. Eight models of continuous reinforced concrete girder were constructed and tested. The test variables were strengthening the splice joints by different schemes of CFRP laminates, presence of horizontal stirrups through the interfaces of the joints and using binder material at the interfaces of the joints. The results showed that strengthening the continuous spliced girders with 45° inclined CFRP laminates led to an increase in the ultimate load in a range of (47 to 74%. Besides, strengthening the continuous spliced girder with horizontal CFRP laminates bonded at its lateral faces could increase the ultimate load by 70%. Additionally, the ultimate load of the continuous spliced girder was increased by (30% due to presence of the horizontal steel stirrups through the interfaces of the joints
Technology provides an evaluator path to improvement for roof bolting machines. Bucyrus offers three different roof bolts models for various mining conditions. The LRB-15 AR is a single-arm boiler recommended for ranges of 32 inches and above; the dual-arm RB2-52A for ranges of 42 inches and above; and the dual-arm RB2-88A for ranges of 54 inches and above. Design features are discussed in the article. Developments in roof bolting technology by Joy Mining Machinery are reported. 4 photos.
Pedersen, Niels Leergaard
The state of stress in bolts and nuts with ISO metric thread design is examined and optimized. The assumed failure mode is fatigue so the applied preload and the load amplitude together with the stress concentrations define the connection strength. Maximum stress in the bolt is found at, the fillet...... under the head, at the thread start or at the thread root. To minimize the stress concentration shape optimization is applied....
Manufacture and tests of shape memory actuators for bolted joints of the oil and gas industry; Fabricacao e testes de atuadores de ligas com memoria de forma para unioes aparafusadas do setor de petroleo e gas
Silva, Niedson J. da; Silva, Marcos M. da [Universidade Federal de Campina Grande (UFCG), PB (Brazil). Curso de Pos-graduacao em Ciencia e Engenharia de Materiais; Araujo, Carlos J. de; Santos, Marco A. dos [Universidade Federal de Campina Grande (UFCG), PB (Brazil). Dept. de Engenharia Mecanica
Shape memory alloys (SMA) actuators have a great potential for applications in the engineering field due to the ability of mechanical force generation through the Shape Memory Effect (SME). The SME behavior is the capacity of SMA remember a form established previously when submitted to a temperature variation. In the oil and gas industry there is a variety of possible applications for these active materials, from thermostatic valves to safety devices for piping. Thus, the aim of this work was to study the technical viability of developing SMA washers for potential application in bolted joints of pipelines to improve the reliability of these joints. NiTi SMA washer actuators were produced through casting by plasma skull melting and molding by Push Pull method using the Discovery all machine from EDG equipment and controls. The NiTi SMA washers were obtained and analyzed using electrical resistance and force generation as a function of temperature. The results of force generation as a function of the temperature have demonstrated that important mechanical efforts can be obtained, justifying the application of these SMA for pipeline joints employed in the oil and gas industry. (author)
Gordon, Ali P.; Drilling Brian; Weichman, Kyle; Kammerer, Catherine; Baldwin, Frank
It has been widely accepted that the phenomenon of time-dependent loosening of flange connections is a strong consequence of the viscous nature of the compression seal material. Characterizing the coupled interaction between gasket creep and elastic bolt stiffness has been useful in predicting conditions that facilitate leakage. Prior advances on this sub-class of bolted joints has lead to the development of (1) constitutive models for elastomerics, (2) initial tightening strategies, (3) etc. The effect of re-torque, which is a major consideration for typical bolted flange seals used on the Space Shuttle fleet, has not been fully characterized, however. The current study presents a systematic approach to characterizing bolted joint behavior as the consequence of sequentially applied torques. Based on exprimenta1 and numerical results, the optimal re-torquing parameters have been identified that allow for the negligible load loss after pre-load application
Bena, Iosif [Institut de Physique Théorique, Université Paris Saclay, CEA, CNRS, 91191 Gif-sur-Yvette Cedex (France); Bossard, Guillaume [Centre de Physique Théorique, Ecole Polytechnique, CNRS, Université Paris-Saclay, 91128 Palaiseau Cedex (France); Katmadas, Stefanos; Turton, David [Institut de Physique Théorique, Université Paris Saclay, CEA, CNRS, 91191 Gif-sur-Yvette Cedex (France)
We introduce a solvable system of equations that describes non-extremal multicenter solutions to six-dimensional ungauged supergravity coupled to tensor multiplets. The system involves a set of functions on a three-dimensional base metric. We obtain a family of non-extremal axisymmetric solutions that generalize the known multicenter extremal solutions, using a particular base metric that introduces a bolt. We analyze the conditions for regularity, and in doing so we show that this family does not include solutions that contain an extremal black hole and a smooth bolt. We determine the constraints that are necessary to obtain smooth horizonless solutions involving a bolt and an arbitrary number of Gibbons-Hawking centers.
Pedersen, Niels Leergaard
The state of stress in bolts and nuts with International Organization for Standardization metric thread design is examined and optimized. The assumed failure mode is fatigue, so the applied preload and the load amplitude together with the stress concentrations define the connection strength....... Maximum stress in the bolt is found at the fillet under the head, at the thread start, or at the thread root. To minimize the stress concentration, shape optimization is applied. Nut shape optimization also has a positive effect on the maximum stress. The optimization results show that designing a nut......, which results in a more evenly distribution of load along the engaged thread, has a limited influence on the maximum stress due to the stress concentration at the first thread root. To further reduce the maximum stress, the transition from bolt shank to the thread must be optimized. Stress reduction...
Bulloch, J.H. [ESB, Power Generation, Dublin (Ireland)
The present presentation describes a detailed study concerning the life assessment and replacement strategy of large turbine casing bolts in a 120 MW steam raising unit. After 122000 hours service, circa 1991/92, the Cr-Mo-V steel casing bolts, involving a total of 184 bolts, from two identical 120 MW units, termed Units 1 and 2, were examined to establish the extent of Reverse Temper Embrittlement, RTE, and creep damage suffered during service. The bolt replacement plans for the two units were as follows; Unit 1 bolts were completely replaced with new bolts while Unit 2 embrittled bolts were withdrawn from service and replaced with Non- Embrittled bolts from Unit 1; basically Unit 2 bolts were made up from a mixture of Unit 1 and 2 Non- Embrittled bolts which had been in service for 122000 hours. Remnant life assessments, concerning both embrittlement and creep damage aspects, were earned out on this series of easing bolts at service times 122000, 150000 and 200000 hours. These assessments involved the use of general embrittlement and creep damage laws which were empirically derived and concerned such parameters as microstructural grain size, bulk phosphorus content and accumulated service strain. (orig.) 7 refs.
A structural investigation of self-consolidating concrete (SCC) in AASHTO Type I precast, : prestressed girders was performed. Six test girders were subjected to transfer length and : flexural testing. Three separate concrete mixtures, two girders pe...
Kim, Junkyeong; Kim, Ju-Won; Lee, Chaggil; Park, Seunghee
The tensile force of pre-stressed concrete (PSC) girders is the most important factor for managing the stability of PSC bridges. The tensile force is induced using pre-stressing (PS) tendons of a PSC girder. Because the PS tendons are located inside of the PSC girder, the tensile force cannot be measured after construction using conventional NDT (non-destructive testing) methods. To monitor the induced tensile force of a PSC girder, an embedded EM (elasto-magnetic) sensor was proposed in this study. The PS tendons are made of carbon steel, a ferromagnetic material. The magnetic properties of the ferromagnetic specimen are changed according to the induced magnetic field, temperature, and induced stress. Thus, the tensile force of PS tendons can be estimated by measuring their magnetic properties. The EM sensor can measure the magnetic properties of ferromagnetic materials in the form of a B (magnetic density)-H (magnetic force) loop. To measure the B-H loop of a PS tendon in a PSC girder, the EM sensor should be embedded into the PSC girder. The proposed embedded EM sensor can be embedded into a PSC girder as a sheath joint by designing screw threads to connect with the sheath. To confirm the proposed embedded EM sensors, the experimental study was performed using a down-scaled PSC girder model. Two specimens were constructed with embedded EM sensors, and three sensors were installed in each specimen. The embedded EM sensor could measure the B-H loop of PS tendons even if it was located inside concrete, and the area of the B-H loop was proportionally decreased according to the increase in tensile force. According to the results, the proposed method can be used to estimate the tensile force of unrevealed PS tendons.
Kim, Ju-Won; Lee, Chaggil; Park, Seunghee
The tensile force of pre-stressed concrete (PSC) girders is the most important factor for managing the stability of PSC bridges. The tensile force is induced using pre-stressing (PS) tendons of a PSC girder. Because the PS tendons are located inside of the PSC girder, the tensile force cannot be measured after construction using conventional NDT (non-destructive testing) methods. To monitor the induced tensile force of a PSC girder, an embedded EM (elasto-magnetic) sensor was proposed in this study. The PS tendons are made of carbon steel, a ferromagnetic material. The magnetic properties of the ferromagnetic specimen are changed according to the induced magnetic field, temperature, and induced stress. Thus, the tensile force of PS tendons can be estimated by measuring their magnetic properties. The EM sensor can measure the magnetic properties of ferromagnetic materials in the form of a B (magnetic density)-H (magnetic force) loop. To measure the B-H loop of a PS tendon in a PSC girder, the EM sensor should be embedded into the PSC girder. The proposed embedded EM sensor can be embedded into a PSC girder as a sheath joint by designing screw threads to connect with the sheath. To confirm the proposed embedded EM sensors, the experimental study was performed using a down-scaled PSC girder model. Two specimens were constructed with embedded EM sensors, and three sensors were installed in each specimen. The embedded EM sensor could measure the B-H loop of PS tendons even if it was located inside concrete, and the area of the B-H loop was proportionally decreased according to the increase in tensile force. According to the results, the proposed method can be used to estimate the tensile force of unrevealed PS tendons. PMID:28867790
Tetsuya Yabuki; Yasunori Arizumi; Tetsuhiro Shimozato; Samy Guezouli; Hiroaki Matsusita; Masayuki Tai
The main object of this paper is to present the research results of the development of a hybrid stainless steel girder system for bridge construction undertaken at University of Ryukyu. In order to prevent the corrosion damage and reduce the fabrication costs, a hybrid stainless steel girder in bridge construction is developed, the stainless steel girder of which is stiffened and braced by structural carbon steel materials. It is verified analytically and experimentally that the ultimate stre...
A number of failures of threaded fasteners in nuclear reactor component supports have been reported. Many of those failures were attributed to stress corrosion cracking. This report discusses how stress corrosion cracking can be avoided in bolting by controlling the maximum bolt preloads so that the sustained stresses in the bolts are below the level required to cause stress corrosion cracking. This is a basic departure from ordinary bolted joint design where the only limits on preload are on the minimum preload. Emphasis is placed on the importance of detailed analysis to determine the acceptable range of preload and the selection of a method for measuring the preload that is sufficiently accurate to ensure that the preload is actually within the acceptable range. Procedures for determining acceptable preload range are given, and the accuracy of various methods of measuring preload is discussed
Nah, H. S.; Lee, H. J.; Kim, K. S.
It is general that the clamping forces of high-strength bolts diminish within a certain time period after the initial clamping force. In case that special treatments are applied on a faying surface, the clamping force is relaxed severely. Tests were conducted for slip critical joints subjected to various faying surface parameters. The candidates for bolt were two kinds: Korean Standard and American Standard. Relaxation occurred for slip resistant joints with an uncoated surface that had been shot-blasted, cleaned, milled or rusted. In case of ASTM hexagon bolts, the initial clamping force dropped from 7.9% to 13.6% after 1, 000 hours while relaxation ratio was the range from 8.7% to 15.4% for KS bolts. For ASTM hexagon bolt joints with a 5 mil thick zinc coating, the clamping force of the bolts decreased 15.0%, while relaxation ratio was 12.85% for KS bolts. For 4.9 mil thick red lead painted treatment, the relaxation ratio was 18.7% for ASTM hexagon bolt, 34.9% for KS bolts. Regardless of faying surface treatments, the first week charged at least 86% of total relaxation from this test. (authors)
Pedersen, Niels Leergaard
Designs of threaded fasteners are controlled by different standards, and the number of different thread definitions is large. The most commonly used thread is probably the metric ISO thread, and this design is therefore used in this paper. Thread root design controls the stress concentration factor...... of threads and therefore indirectly the bolt fatigue life. The root shape is circular, and from shape optimization for minimum stress concentration it is well known that the circular shape is seldom optimal. An axisymmetric Finite Element (FE) formulation is used to analyze the bolted connection, and a study...... is performed to establish the need for contact modeling with regard to finding the correct stress concentration factor. Optimization is performed with a simple parameterization with two design variables. Stress reduction of up to 9% is found in the optimization process, and some similarities are found...
Full Text Available Steel trusses are the most popular system for supporting long-span roofs in commercial buildings, such as warehouses and aircraft hangars. There are several advantages of steel trusses, such as lightweight, ease of handling and erection, and geometric flexibility. However, they have some drawbacks, such as high material and maintenance cost, and low fire resistance. In this paper, a precast concrete truss is proposed as an alternative to steel trusses for spans up to 48 m (160 ft without intermediate supports. The proposed design is easy to produce and has lower construction and maintenance costs than steel trusses. The truss consists of two segments that are formed using standard bridge girder forms with block-outs in the web which result in having diagonals and vertical members and reduces girder weight. The two segments are then connected using a wet joint and post-tensioned longitudinally to form a crowned truss. The proposed design optimizes the truss-girder member locations, cross-sections, and material use. A 9 m (30 ft long truss specimen is constructed using self-consolidated concrete to investigate the constructability and structural capacity of the proposed design. A finite element analysis of the specimen is conducted to investigate stresses at truss diagonals, verticals, and connections. Testing results indicate the production and structural efficiency of the developed system.
Full Text Available In this paper, we report our findings on implementing a synthetic phased array surface acoustic wave sensor to quantify bolt tension. Maintaining proper bolt tension is important in many fields such as for ensuring safe operation of civil infrastructures. Significant advantages of this relatively simple methodology is its capability to assess bolt tension without any contact with the bolt, thus enabling measurement at inaccessible locations, multiple bolt measurement capability at a time, not requiring data collection during the installation and no calibration requirements. We performed detailed experiments on a custom-built flexible bench-top experimental setup consisting of 1018 steel plate of 12.7 mm (½ in thickness, a 6.4 mm (¼ in grade 8 bolt and a stainless steel washer with 19 mm (¾ in of external diameter. Our results indicate that this method is not only capable of clearly distinguishing properly bolted joints from loosened joints but also capable of quantifying how loose the bolt actually is. We also conducted detailed signal-to-noise (SNR analysis and showed that the SNR value for the entire bolt tension range was sufficient for image reconstruction.
Huang, Yong-Kuo; Tu, Yun; Tu, Shan-Tung
Insufficient or excessive preload has been regarded as the main issue that may endanger the safety of bolted joints operated at high temperatures. A new technique for monitoring the bolt clamping force is thus proposed using metal-packaged regenerated fiber Bragg grating (RFBG) strain sensors spot-welded onto the bolt. The measurement of the clamping force in a bolted steel-steel joint subjected to thermal loading is conducted. The experimental results show that the bolt clamping force can be monitored by the metal-packaged RFBG strain sensor at high temperatures up to 500 °C. This technique provides a new possibility for structural health monitoring of bolted joints operated at high temperatures.
The paper deals with modelling and calculations of asymmetrical multi-bolted joints at the assembly stage. The physical model of the joint is based on a system composed of four subsystems, which are: a couple of joined elements, a contact layer between the elements, and a set of bolts. The contact layer is assumed as the Winkler model, which can be treated as a nonlinear or linear model. In contrast, the set of bolts are modelled using simplified beam models, known as spider bolt models. The theorem according to which nonlinearity of the contact layer has a negligible impact on the final preload of the joint in the case of its sequential tightening has been verified. Results of sample calculations for the selected multi-bolted system, in the form of diagrams of preloads in the bolts as well as normal contact pressure between the joined elements during the assembly process and at its end, are presented.
Kauer, R.; Deininger, J.
In Europe as well as in other countries a lot of efforts are invested into developing new codes and standards for bolted joints under various loading conditions. The standardization of gasket factors and the improvement of calculation methods with respect to these factors characterize the last couple of years in this area. In Germany, the nuclear code (KTA-Regeln) is also influenced by this development. So, the leak rate dependency of gasket factors and the results of a research program on metal-to-metal contact type flanges were introduced into the new approach of the code for Class 2 and 3 components. Herein; flange calculations can be performed for various flange types, floating type and metal-to-metal contact type. Generally, the calculations to be performed can be separated into a design step and the proof of sufficient tightness and strength of flange, bolts and gasket for the various operating conditions according to the chosen bolting method. In Europe, the most recent development in the field of flange calculations is the new standard EN 1591-1 for flange connections. The structure of the EN 1591-1 is also a two-step approach, but due to the more sophisticated and iterative calculation method, the design step is neglected and instead the focus in the first step is the determination of a suitable bolting force. In cases, where the allowable stress values are not satisfied by performing code calculations or in cases, where the applicability of the code is not given, e. g. due to geometric facts, Finite-Element analyses often replace code calculations but have to demonstrate code compliance. Therefore, numerical Finite-Element analyses, performed according to a special code, e. g. KTA, must also fulfill the requirements of the code with respect to considered load cases, bolting condition, allowable stresses etc., to get an adequate testimony for a certain flange joint. Usually this can be done by checking relevant cross sections according to the stress
Hopkins, Ronald Neil; Heitman, Lili Anne Akin
Relative motion at bolted connections can occur for large shock loads as the internal shear force in the bolted connection overcomes the frictional resistive force. This macroslip in a structure dissipates energy and reduces the response of the components above the bolted connection. There is a need to be able to capture macroslip behavior in a structural dynamics model. A linear model and many nonlinear models are not able to predict marcoslip effectively. The proposed method to capture macroslip is to use the multi-body dynamics code ADAMS to model joints with 3-D contact at the bolted interfaces. This model includes both static and dynamic friction. The joints are preloaded and the pinning effect when a bolt shank impacts a through hole inside diameter is captured. Substructure representations of the components are included to account for component flexibility and dynamics. This method was applied to a simplified model of an aerospace structure and validation experiments were performed to test the adequacy of the method.
Zhang, Zhen; Liu, Menglong; Liao, Yaozhong; Su, Zhongqing; Xiao, Yi
The significance of evaluating bolt tightness in engineering structures, preferably in a continuous manner, cannot be overemphasized. With hybrid use of high-order harmonics (HOH) and spectral sidebands, a contact acoustic nonlinearity (CAN)-based monitoring framework is developed for detecting bolt loosening and subsequently evaluating the residual torque on a loose bolt. Low-frequency pumping vibration is introduced into the bolted joint to produce a "breathing" effect at the joining interface that modulates the propagation characteristics of a high-frequency probing wave when it traverses the bolt, leading to the generation of HOH and vibro-acoustic nonlinear distortions (manifested as sidebands in the signal spectrum). To gain insight into the mechanism of CAN generation and to correlate the acquired nonlinear responses of a loose joint with the residual torque remaining on the bolt, an analytical model based on micro-contact theory is established. Two types of nonlinear index, respectively exploiting the induced HOH and spectral sidebands, are defined without dependence on excitation intensity and are experimentally demonstrated to be effective in continuously monitoring bolt loosening in both aluminum-aluminum and composite-composite bolted joints. Taking a step further, variation of the index pair is quantitatively associated with the residual torque on a loose bolt. The approach developed provides a reliable method of continuous evaluation of bolt tightness in both composite and metallic joints, regardless of their working conditions, from early awareness of bolt loosening at an embryonic stage to quantitative estimation of residual torque.
... anchor trailing cables or used for any other purpose that could affect the tension of the bolt. Hanging... tension ranges for roof bolts as specified in the roof control plan shall maintain the integrity of the.... (4) In each roof bolting cycle, the actual torque or tension of the first tensioned roof bolt...
These two volumes provide the documentation for industry resolution of the US Nuclear Regulatory Commission (NRC) generic issue B-29, Degradation and Failure of Bolting in Nuclear Power Plants. The issue was identified as a consequence of concerns about the structural integrity of component supports circa 1980. When bolting integrity became a separate issue in 1982, the utility industry responded by forming a Task Group on Bolting under the aegis of the Atomic Industrial Forum (AIF) and the Materials Properties Council (MPC). The AIF/MPC Task Group on Bolting formulated a comprehensive nineteen-task action plan aimed at resolution of the issue, with implementation of the plan, the responsibility of EPRI and the affected Owner's Groups. EPRI organized a matrix-managed Generic Bolted Joint Integrity Program to carry out the research, with the results reported herein
"Prestressed concrete girders are an economical superstructure system for bridges. With the : advent of higher strength concretes and more effi cient cross sections, the use of long span (>100 : ft.) prestressed girders are now specifi ed. Such long ...
The design of prestressed concrete bridge girders has changed significantly over the past several : decades. Specifically, the design procedure to calculate the shear capacity of bridge girders that : was used forty years ago is very different than t...
Wide cracks were discovered in prestressed concrete bridge girders shortly after their construction in Huntsville, Alabama. Previous investigations of these continuous-for-live-load girders revealed that the cracking resulted from restrained thermal ...
End diaphragms connect multiple girders to form a bridge superstructure system for effective resistance to earthquake loads. Concrete : girder bridges that include end diaphragms consistently proved to perform well during previous earthquake events. ...
Full Text Available Modelling and calculations of a contact layer between elements joined in a preloaded bolted connection for the operational condition are presented. The physical model of the bolted connection is based on a flexible flange element that is joined with a rigid support by means of the no-bolt model (at the assembly stage or the rigid body bolt model (at the operational stage. The contact layer between joined elements is described as the nonlinear Winkler model. The contact joint model considering an experimental normal elastic characteristic is presented. Examples of normal contact pressure and normal contact deformations distributions are contained.
.... Two approaches were implemented. A conventional mesh overlay method in the crack region to satisfy the crack face boundary conditions and a novel spline basis partitioning method were compared...
Full Text Available Loss of pre-load with time, commonly known as ‘Relaxation’ is an established phenomena. Behaviour of a bolted joint depends upon the pre-load in the bolts in use, not the pre-load introduced by the mechanic. Loss of pre-load is expected due to the many factors such as embedment relaxation, gasket creep, elastic interactions, and vibration loosening or stress relaxation. In a gasketed joint, due to the gasket flexibility, relaxation is always substantial during preliminary passes, as 80 to 100% loss is not uncommon in almost all the bolts, resulting in a dynamic behaviour. Pre-load in a gasketed joint is stabilized and retained to certain extent in the final passes only. In a non-gasketed joint, due to no gasket and no rotation its static behaviour is concluded. This paper highlights the factors affecting the amount of relaxation with time and presents important considerations that can reduce this. Both the short and long term relaxations are recorded and a ‘best fit’ model for relaxation behaviour is derived.
Full Text Available Steel-concrete composite girders have attractive potentials when applied in bridge construction. The serviceability performance of continuous composite girders is becoming more and more a deterministic parameter in the design of this type of structures. An effective method for improving this performance is to apply prestressing to control or completely eliminate concrete deck cracking caused by static and time dependent actions. Little literature has been found addressing the experimental analysis of continuous girders prestressed by means of external deviated tendons. The current research aims to investigate the behavior of a double-span steel composite beam externally prestressed by means of continuous tendons in terms of cracking characteristics, load deflection response, and load carrying capacity. The efficiency of prestressing is evaluated by comparing the results to those of a non-prestressed beam with similar cross sections and spans.
Reactor vessel stud bolt handling equipment includes means for transferring a stud bolt to a carrier from a parking station, or vice versa. Preferably a number of stud bolts are handled simultaneously. The transfer means may include cross arms rotatable about extendable columns, and the equipment is mounted on a mobile base for movement into and out of position. Each carrier comprises a tubular socket and an expandable sleeve to grip a stud bolt. (author)
Full Text Available This paper compares the effect of temperature changes on the superstructure of bridges, above all the effect of non-uniform temperature. Loadings according to standards ESN 73 6203, ENV 1991-1-5 and DIN 1072 are compared here. The paper shows a short summary of temperature loading according to each standard and shows the comparison of bending moments arisen from these temperature loadings on superstructure made from continuous girder from a steel-concrete box girder with a composite concrete slab. With respect to a variety of design processes, the comparison is made without any coefficient of loading, combination or material.
Reverse diagonal shear cracking at reinforced concrete girder supports affects many low-volume bridges built : in the early 1900s in Kansas. This phenomenon, however, is not addressed in the American Association of State : Highway and Transportation ...
V. I. Burenin
Full Text Available Results of study of the collection accessions of red beet with different level of bolting resistance are presented. Nature of inheritance of this trait in progeny, and also its connection with other biological and economically valuable characters and properties is shown. Bolting resistant accessions and possibility of its use in breeding are described. The promising initial material is selected and recommended. The most rational solution of the bolting problems in the beet is the development of resistant varieties and hybrids. For this purpose, the early-spring and under-winter planting are used, as well as the seed germination at low (30C temperatures. The availability of the various initial material studied by modern methods of researches plays a key role. When the collection accessions of beet were studied in the VIR Polar branch (The Murmansk Region, the following genotypes were identified: 1 – non bolting, 2 – weak bolting (less than 10% of bolting plants, 3 – moderately bolting (10-50%, and 4 – high bolting (more than 50% of bolting plants. As a result of screening of a gene pool, the genetic sources of bolting resistance of beet were identified. At its crossing with bolting accessions the dominance of the trait «bolting» and monogenic nature of its inheritance are confirmed. For the purpose of beet breeding for bolting resistance, the symphycarpous varieties characterized by complex biological and agronomic characters (increased yield, cold tolerance, quality of production and resistance to blackleg are the most usable. The cultivars Banko from Sweden (donor, Podzimnyaya A-0474 (VNIISSOK and Polyarnaya ploskaya-249 (Polar branch VIR are recommended as a genetic sources of bolting resistance.
Most highway bridges are built as cast-in-place : reinforced concrete slabs and prestressed concrete : girders. The shear connectors on the top of the girders : assure composite action between the slabs and : girders. The design guidelines for bridge...
Claydon, S M
The crossbow was one of the most efficient military weapons of the Middle Ages but the development of portable firearms meant that it was eventually relegated to the museum shelf. The medieval crossbow was accurate and deadly but took some time to load because of the windlass used to wind the string, thus increasing the velocity and range of the bolt, or quarrel. By contrast, the English longbows of Crecy and Agincourt were far less accurate but could fire six arrows in the time taken to shoot one bolt and the continual raining-down of missiles proved more successful in battle than accuracy of aim. This paper describes the homicide of a young business woman outside her London flat in 1987. Today crossbow fatalities are extremely rare on both sides of the Atlantic but Dr Siva described a case of suicide in 1979 and Professor Gresham presented a case of crossbow homicide to the BAFM in June 1976.
McCutcheon, S.H.; Waaser, R.E.
The Savannah River Plant (SRP) is operated for the U.S. Department of Energy (DOE) by E.I. du Pont de Nemours and Co. Reactors at SRP are used to produce nuclear isotopes for national defense. As part of the routine operation of each of the reactors, irradiated fuel assemblies are remotely discharged from the reactor, transferred in air, and placed underwater in a Deposit and Exit (D and E) canal. The D and E conveyor transports the assemblies under the reactor room wall into the disassembly basin, where they are stored for several months before shipment to the separations areas. On August 13, 1980, a broken bolt was discovered on the D and E conveyor during a routine pre-operational inspection. The failed bolt was one of four which anchor a bearing on one of the conveyor drive shafts. All four of the bolts on the affected bearing were replaced as an immediate corrective measure and the discharge of irradiated fuel assemblies was subsequently completed without difficulty
Wang, Feng-Lan; Zhang, Bo; Gao, Bo; Liu, Yan-Xin; Gao, Bo
Expansion bolt is a kind of the most common things in our daily life. Currently, there are many kinds of expansion bolts in the market. However, they have some shortcomings that mainly contain underuse and unremovement but our innovation of design makes up for these shortcomings very well. Principle of working follows this: expansion tube is fixed outside of bolt, steel balls and expansion covers are fixed inside. Meanwhile, the steel balls have 120° with each other. When using it ,expansion cover is moved in the direction of its internal part. So the front part of expansion bolt cover is increasingly becoming big and steel halls is moved outside. Only in this way can it be fixed that steel balls make expansion tube expand. When removing them, expansion bolt is moved outside. So the front part of expansion bolt cover is gradually becoming small and steel balls moves inside, after expansion tube shrinks, we can detach them.
Full Text Available This paper focuses on the nonlinear dynamics modeling and parameter identification of an Aluminum Honeycomb Panel (AHP with multiple bolted joints. Finite element method using eight-node solid elements is exploited to model the panel and the bolted connection interface as a homogeneous, isotropic plate and as a thin layer of nonlinear elastic-plastic material, respectively. The material properties of a thin layer are defined by a bilinear elastic plastic model, which can describe the energy dissipation and softening phenomena in the bolted joints under nonlinear states. Experimental tests at low and high excitation levels are performed to reveal the dynamic characteristics of the bolted structure. In particular, the linear material parameters of the panel are identified via experimental tests at low excitation levels, whereas the nonlinear material parameters of the thin layer are updated by using the genetic algorithm to minimize the residual error between the measured and the simulation data at a high excitation level. It is demonstrated by comparing the frequency responses of the updated FEM and the experimental system that the thin layer of bilinear elastic-plastic material is very effective for modeling the nonlinear joint interface of the assembled structure with multiple bolts.
Full Text Available The contribution is focused on reliability of balcony girders of a Czech national heritage monument. As preliminary reliability assessment suggests insufficient resistance, a series of nondestructive tests supplemented by a single tensile test are performed and evaluated by the statistical methods. Values of material properties, recommended in standards for historic materials, seem to be overly conservative and it is advised to specify properties of historic metallic materials by tests.
Full Text Available Determination of the local interlaminar stress distribution in a laminate with a bolt-filled hole is helpful for optimal bolted joint design, due to the three-dimensional (3D nature of the stress field near the bolt hole. A new interlaminar stress distribution phenomenon induced by the bolt-head and clamp-up load, which occurs in a filled-hole composite laminate, is investigated. In order to efficiently evaluate interlaminar stresses under the complex boundary condition, a calculation strategy that using zero-thickness cohesive interface element is presented and validated. The interface element is based on a linear elastic traction-separation description. It is found that the interlaminar stress concentrations occur at the hole edge, as well as the interior of the laminate near the periphery of the bolt head. In addition, the interlaminar stresses near the periphery of the bolt head increased with an increase in the clamp-up load, and the interlaminar normal and shear stresses are not at the same circular position. Therefore, the clamp-up load cannot improve the interlaminar stress distribution in the laminate near the periphery of the bolt head, although it can reduce the magnitude of the interlaminar shear stress at the hole edge. Thus, the interlaminar stress distribution phenomena may lead to delamination initiation in the laminate near the periphery of the bolt head, and should be considered in composite bolted joint design.
Regarding the high tensile strength and proper module of elasticity, CFRP plates are considered as a suitable alternative to strengthen girders. The behaviour of steel–concrete composite girders being statically loaded and strengthened by CFRP plates in this study. The CFRP plates used in this study have been stuck, with ...
Maljaars, J.; Steenbergen, H.M.G.M.; Stark, J.W.B.; Abspoel, R.
The lateral torsional buckling resistance of girders depends on the support conditions. In floor structures for buildings, coped girders are often used. A numerical model was developed to research the influence of copes on lateral buckling resistance. The model is successfully validated with tests.
Wang, Furui; Huo, Linsheng; Song, Gangbing
Monitoring of bolt looseness is essential for ensuring the safety and reliability of equipment and structures with bolted connections. It is well known that tangential damping has an important influence on energy dissipation during wave propagation across the bolted joints, which require different levels of preload. In this paper, the energy dissipation generated by tangential damping of the bolted joints under different bolt preloads was modeled analytically based on fractal contact theory, which took the imperfect interface into account. A saturation value exists with the increase of the bolt preload, and the center frequency of emitted signal is demonstrated to affect the received energy significantly. Compared with previous similar studies based on experimental techniques and numerical method, the investigation presented in this paper explains the phenomenon from the inherent mechanism, and achieves the accurate quantitative monitoring of bolt looseness directly, rather than an indirect failure index. Finally, the validity of the proposed method in this paper was demonstrated with an experimental study of a bolted joint with different preload levels.
Da-wei, Gao; Gui-jie, Shi
Hull girder ultimate strength is an evaluation index reflecting the true safety margin or structural redundancy about container ships. Especially, after the hull girder fracture accident of the MOL COMFORT, the 8,000TEU class large container ship, on June 17 2013, larger container ship safety has been paid on much more attention. In this paper, different methods of calculating hull girder ultimate strength are firstly discussed and compared with. The bending ultimate strength can be analyzed by nonlinear finite element method (NFEM) and increment-iterative method, and also the shear ultimate strength can be analyzed by NFEM and simple equations. Then, the probability distribution of hull girder wave loads and still water loads of container ship are summarized. At last, the reliability of hull girder ultimate strength under bending moment and shear forces for three container ships is analyzed by using a first order method. The conclusions can be applied to give guidance for ship design and safety evaluation.
Pinaud, T.; Grypczynski, D.
Both Framatome Nuclear Services in France and its U.S. arm, FT1, are now equipped with baffle bolt inspection and replacement packages. These packages allow them to tackle baffle bold degradation on both two- and three-loop nuclear power plants. Framatome and FT1 together are world leaders in addressing reactor vessel internal bolting concerns
A cornerstone publication that covers the basic principles and practical considerations of design methodology for joints held by rivets, bolts, weld seams, and adhesive materials, Design of Mechanical Joints gives engineers the practical results and formulas they need for the preliminary design of mechanical joints, combining the essential topics of joint mechanics...strength of materials...and fracture control to provide a complete treatment of problems pertinent to the field of mechanical connections.
Bijlaard, F.S.K.; Brekelmans, J.W.P.M.
Traditionally for Western Europe countries, joints in steel frame structures are realised using bolts and welds. In the workshop the components are made using welding and drilling of the bolt holes. On site these structural components are connected together using bolts and nuts. The actions on site
Full Text Available This study deals with unconventional bearing capacity analysis and the procedure of optimizing a two-cell box girder. The generalized model which enables the local stress-strain analysis of multicell girders was developed based on the principle of cross-sectional decomposition. The applied methodology is verified using the experimental data (Djelosevic et al., 2012 for traditionally formed box girders. The qualitative and quantitative evaluation of results obtained for the two-cell box girder is realized based on comparative analysis using the finite element method (FEM and the ANSYS v12 software. The deflection function obtained by analytical and numerical methods was found consistent provided that the maximum deviation does not exceed 4%. Multicell box girders are rationally designed support structures characterized by much lower susceptibility of their cross-sectional elements to buckling and higher specific capacity than traditionally formed box girders. The developed local stress model is applied for optimizing the cross section of a two-cell box carrier. The author points to the advantages of implementing the model of local stresses in the optimization process and concludes that the technological reserve of bearing capacity amounts to 20% at the same girder weight and constant load conditions.
to high pressure and high temperature applications. In a gasketed pipe flange joint, prob- lem of bolt scatter, bolt bending and joint relaxation is observed; resulting in the dynamic mode-of-load (Abid & Nash 2006; Abid 2000). Dynamic mode here represents a situation where the flange faces move and rotate relative to one ...
Full Text Available The cranes are now not replaceable mode of transport of materials and finished products both in production halls and in the open space. This paper made the whole analytical calculation of double girder bridge cranes to be used in laboratories exclusively for testing, determined by the maximum bending stress and deflection of the main girder. After calculating the dimensions, we created a model cranes in software CATIA V5. The same model was subjected to FEM analysis of the same name software. At the end of the paper comparison has been done. The objective of the calculation and analysis of the model was to develop a model crane and to serve for the next tests. Dimensions of the crane are given according to the laboratory where it will be located.
... steel stud bolts must be threaded full length or, if desired, may have reduced shanks of a diameter not less than that at the root of the threads. They must have heavy semifinished hexagonal nuts in...
Volkov, Nikolai; Finkelstein, Nir; Novoselsky, Yehuda; Tsach, Tsadok
Bolt cutters are known as cutting tools which are used for cutting hard objects and materials, such as padlocks and bars. Bolt cutter blades leave their imprint on the cut objects. When receiving a cut object from a crime scene, forensic toolmarks examiners can determine whether the suspected cutting tool was used in a specific crime or not based on class characteristic marks and individual marks that the bolt cutter blades leave on the cut object. The paper presents preliminary results of a study on ten bolt cutters and suggests a quick preliminary examination-the comparison between the blade thickness and the width of the imprint left by the tool on the cut object. Based on the comparison result, if there is not a match, the examiner can eliminate the feasibility of the use of the suspected cutting tool in a specific crime. This examination simplifies and accelerates the comparison procedure. © 2015 American Academy of Forensic Sciences.
The construction of highway bridges using precast prestressed concrete (PSC) girders is considered one of the most : economical construction alternatives because of the advantages they offer (e.g. reducing formwork and rapid construction). : Construc...
Precast prestressed concrete I-Girder bridges have become the most dominant bridge system in the United States. In the early design : stages, preliminary design becomes a vital first step in designing an economical bridge. Within the state of Nebrask...
End region detailing has significant effect on the serviceability, behavior, and capacity of pretensioned concrete girders. : In this project, experimental and analytical research programs were conducted to evaluate and quantify the effects of : diff...
This document reports the findings of a research project designed to better understand material and structural performance of prestressed bridge girders made with Self-Consolidating Concrete (SCC) from Wisconsin. SCC has high potential to be used for...
Self-consolidating concrete (SCC) is commonly used as an alternative to conventional concrete (CC) in precast, prestressed concrete (PSC) bridge girders. The high strength, highly workable mixture can flow through dense reinforcement to fill formwork...
This research study investigates the behavior of two long prestressed concrete girders during lifting and : transportation from the precast yard to the bridge site, with a particular focus on cracking concerns : during transport. Different response m...
Full Text Available Comprehensive methodology of numerical nonlinear analysis of the consecutive phases in the structural behaviour of bridge plate girders with deformations is presented. The analysis concerns all stages of structure loading until failure and especially determination of the ultimate shear load capacity. Verification and validation of the numerical procedures proposed is based on comparison of the calculated results with effects of experimental laboratory shear capacity tests of plate girders carried out at the University of Ljubljana.
Full Text Available To research structural performance of extra-large-span cable-stayed bridge under different section forms, with the engineering background of a 800m main-span cable-stayed bridge with steel truss girder, the cable-stayed bridge with steel box girder is designed according to the current bridge regulations when two bridges are designed in an ultimate state of the carrying capacity, so the maximum stress and minimum stress of the stress envelope diagram are substantially the same. A comprehensive comparison is given to two types of bridge on the aspect of static force, natural vibration frequency, stability, economic performance and so on. Analysis results provide future reference for the large-span cable-stayed bridge to select between the steel truss girder and the steel box girder.
A user interface creates a grillage model of an existing bridge and places various rating trucks on the : bridge. Equivalent flexibility analysis distributes truck live loads within deck panels to surrounding : girders and diaphragms. Stiffness matri...
Jimenez Chong, Juan Manuel
Closed structural sections, such as those having circular, rectangular or trapezoidal shape, possess high rotational rigidity when compared to open sections such as I-girders. The high torsional rigidity of closed sections makes them ideal for use in highly curved bridges. In this case, the geometry of the bridge results in large torsional forces. Because of structural efficiency and economy reasons, most of these closed-section bridges consist of a trapezoidal cross-section, with a top concrete slab and bottom and side steel plates. The slab is cast after the steel is erected and thus a system of internal diaphragms and braces is necessary to stabilize the system during erection. During the steel erection and the early stages of the concrete deck placement, the section can be considered as quasi-closed as the top concrete flange has not been cast or is not yet effective. During steel erection, undetermined and/or large torsional forces and/or displacements may result in fit-up problems requiring large stresses to overcome. During concrete deck placement, the undetermined displacements can affect the control of the deck thickness and the final deck geometry, such as the alignment of deck joints and the matching of stages in phased constructions projects. Due to the interactions between their various components, the behavior of curved and skewed tub-girder bridges is significantly more complex than that of straight bridges. When skewed supports are used in tub-girders, the interaction of the girder bending rotations and the displacement constraints induced by the skewed support diaphragms causes twisting of the girders at the supports. These twist rotations introduce additional torques into the system. Both curvature and skew can cause design and construction difficulties, especially at the supports, where the corresponding steel dead load deflections and the large torsional stiffness of the girders may lead to large fit-up forces. Currently, the general
Herrera, M.; Mattson, R.
Implementation of Noble Metal Chemical Application (NMCA) in a Boiling Water Reactor (BWR) requires injection of a noble metal compound while the reactor is idle at hot shutdown conditions. In order to minimize outage time, utilities are very pro-actively finding ways to reduce the number of critical path tasks. One of these tasks is to remove some containment vessel drywell head bolts during the NMCA idle time. This, thereby, saves the utilities outage time, or they can perform other tasks as desired. Using design basis conditions and state-of-the-art analytical techniques, detailed finite element stress analyses of the closure region are performed. Two acceptance criteria are evaluated. The first is that contained within Section III of the ASME Code for allowable stresses. The second relates to leak tightness, i.e., with bolt removal the joint must still remain leak tight. This paper describes the activities performed to justify bolt removal during the noble metal compound injection idle time at a particular plant. Drywell joint integrity criteria, design input, and assumptions are defined, and analytical results justifying bolt removal are presented. (author)
In bridges constructed with precast prestressed concrete girders, resistance to seismic effects is achieved by the interaction between the columns, the cap beam and the girders. These components must be connected to provide flexural resistance. Under...
Hundreds of prestressed concrete girders are used each year for building bridges in Wisconsin. : The prestress transfer from the prestressing strands to concrete takes place at the girder ends. : Characteristic cracks form in this end region during o...
Encouraged by the performance of high performance normal weight composite girders, the Virginia Department of Transportation has sought to exploit the use of high performance lightweight composite concrete (HPLWC) girders to achieve economies brought...
The Jakway Park Bridge in Buchanan County, Iowa is the first bridge constructed with a new prestesssed girder system composed of : precast Ultra-High Performance Concrete (UHPC). These girders employ an integral deck to facilitate construction and ar...
The design of prestressed concrete bridge girders has changed significantly over the past several decades. Specifically, the design procedure to calculate the shear capacity of bridge girders that was used forty years ago is very different than those...
Skew of the supports in steel I-girder bridges cause undesirable torsional effects, increase cross-frame forces, and generally increase the difficulty of designing and : constructing a bridge. The girders experience differential deflections due to th...
Pakarinen, J.; Ehrnsten, U.; Keinaenen, H.; Karlsen, W.; Karlsen, T.
Analytical transmission electron microscopy (ATEM) was used to examine irradiation-induced damage in material removed from two different bolts from two different nuclear power plants. One section came from a French PWR, was made of CW AISI 316, and included a section of the bolt that had accumulated a dose of approximately 15 dpa during 19 operation cycles at 350 - 390 C. degrees. Another section came from a VVER bolt that was removed from the plant due to indications found in non-destructive examinations (NDE). The VVER bolt was made of solution annealed titanium stabilized 0X18H10T (corresponding to Type AISI 321) and had accumulated a fluence of 2.9 dpa. During the removal of that bolt, it was found that the bolt washer had been inappropriately spot welded to the shielding plate during assembly. Destructive investigations showed that the bolt had two large intergranular cracks, and the TEM samples were prepared from the material adjacent to those cracks. The PWR bolt had not failed, although cracks in the bolts with a similar history had been found previously. The fluence for the cold-worked AISI 316 PWR bolt was estimated to be about 15 dpa. Both the examined bolts showed a clear radiation induced segregation of alloying elements at the grain boundaries (GB-RIS), the presence of dislocation loops, the formation of precipitates, and linear deformation microstructures. Additionally, voids were found from the PWR bolt and the VVER bolt had a high density of dislocations. (authors)
Fabián Augusto Lamus Báez
Full Text Available In a bolted joint of structures that use Guadua angustifolia as the main supporting material, the resistance to the double metal shears paralleled to fiber could be influenced by an extensive list of parameters including parallel to fiber crushing resistance, parallel to metal fiber resistance of the wall and the contact area between elements in the joint. This paper presents experimental results for the resistance to the double metal shears paralleled to fiber, when the element is loaded under compression, for different culm diameters. Moreover, we studied the influence of the bolt diameter and culm thickness in the joint resistance. The tests were conducted on specimens of Guadua angustifolia with variable diameters between seven and fourteen centimeter where bolts of 3/8, 1/2 and 3/4" diameter were used. The Guadua tested came from the outskirts of Armenia in Colombia. It was found that the great amount of the double metal shears paralleled to fiber in the joint is provided by parallel to fiber crushing resistance of the Guadua.
Full Text Available of magnetic methods in measuring the stress or microstructural transformation in an individual bolt in both laboratory and underground environment. The corrosion performance of the smart bolt alloy was evaluated in synthetic mine water and compared...
Lechner, Joseph H.
Several additions to a classroom activity are proposed in which an "enzyme" (the student) converts "substrates" (nut-bolt assemblies) into "products" (separated nuts and bolts) by unscrewing them. (Contains 1 table.)
... TREASURY ARTICLES CONDITIONALLY FREE, SUBJECT TO A REDUCED RATE, ETC. General Provisions Bolting Cloths... used in the act or process of grading, screening, bolting, separating, classifying, or sifting dry...
Czarnecki, R.M.; Manrique, M.A.; Samaddar, S.K.
A summary of available experimental expansion anchor bolt test data is presented. These data were collected as part of programs by the nuclear industry to address generic issues related to verification of seismic adequacy of equipment in nuclear power plants. Some of the data presented are suitable for use in seismic probabilistic risk assessments. For example, mean values of ultimate strength, along with their standard deviation and coefficients of variation, for a range of most typical expansion anchor bolt sizes are presented. Effects of interaction between shear and tension, edge distance, spacing, and cracking of the concrete are presented in a manner that is more suitable for use in deterministic evaluations. Related industry programs to derive anchor bolt capacities are briefly discussed. Recommendations for areas of further investigation are also presented
In steel construction, the importance of connection cannot be overemphasized. Steel connection can be made of bolts, rivets and welding. The quality of bolts, rivets and welds in structural steel connection affects the connection and hence the capacity of the whole steel structure. This paper examined the quality of bolts and ...
... 21 Food and Drugs 2 2010-04-01 2010-04-01 false Bolted white corn meal. 137.255 Section 137.255 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD... Flours and Related Products § 137.255 Bolted white corn meal. (a) Bolted white corn meal is the food...
Kockelmann, H.; Hahn, R.
Great progress was observed in the European standardization in the last years in the field of the design of floating type bolted flange connections. New design rules were developed (EN 1591) which include new definitions of gasket characteristics for the calculation of floating type flanged joints. In addition a new gasket testing standard was drafted (prEN 13555) which assures a comprehensive characterization of gaskets for bolted flanged joints. This draft standard contains some new features which were examined and validated within the European research project PERL (Pressure Equipment - Reduction of Leak Rate). The gasket testing strategy laid down in prEN 13555 is presented in this paper. Some testing results highlighten the measuring procedures and the evaluation of the gasket characteristics. (orig.)
Full Text Available A finite segment method is presented to analyze the mechanical behavior of skewed box girders. By modeling the top and bottom plates of the segments with skew plate beam element under an inclined coordinate system and the webs with normal plate beam element, a spatial elastic displacement model for skewed box girder is constructed, which can satisfy the compatibility condition at the corners of the cross section for box girders. The formulation of the finite segment is developed based on the variational principle. The major advantage of the proposed approach, in comparison with the finite element method, is that it can simplify a three-dimensional structure into a one-dimensional structure for structural analysis, which results in significant saving in computational times. At last, the accuracy and efficiency of the proposed finite segment method are verified by a model test.
Ertekin Öztekin Öztekin
Full Text Available Design of the distance of bolts to each other and design of the distance of bolts to the edge of connection plates are made based on minimum and maximum boundary values proposed by structural codes. In this study, reliabilities of those distances were investigated. For this purpose, loading types, bolt types and plate thicknesses were taken as variable parameters. Monte Carlo Simulation (MCS method was used in the reliability computations performed for all combination of those parameters. At the end of study, all reliability index values for all those distances were presented in graphics and tables. Results obtained from this study compared with the values proposed by some structural codes and finally some evaluations were made about those comparisons. Finally, It was emphasized in the end of study that, it would be incorrect of the usage of the same bolt distances in the both traditional designs and the higher reliability level designs.
Sears, Gary; King, David
Plant owners are coming under ever increasing pressure to reduce fugitive emissions for a number of reasons including environmental (legislation) and safety and commercial (plant efficiency). The real cost of fugitive emissions is frequently not fully appreciated. A number of the resultant costs are often difficult to quantify such as loss of product, cost of labour/materials to repair leaks, cost of cleaning the affected area, environmental fines, and image. Joint integrity management service is the total package of services that provides the best possible chance of achieving a leak-free start-up. It includes engineering analysis, unbolting, inspection, machining as required, gasket installation assembly, controlled bolt up and full documentation/traceability. The assembly of a joint is not just about installing a gasket and tightening the bolts. Correct assembly of critical joint requires that the flange is analysed and the correct bolt load to seal the joint is established. It requires the most suitable gasket to be installed for the service, flange flatness/condition to be inspected and for the determined bolt load to be applied in a controlled manner. Incorrect bolt loads, flange distortion, inappropriate gasket selection and uncontrolled flange assembly/bolt tightening methods are the main reasons for joint leaks. By taking some simple steps these potential causes for failure can be eliminated
Lei Cao; Song Yuntao; Zhou Zibo; Xu Weiwei
The first wall in Experimental Advanced Superconducting Tokamak (EAST) has used many graphite tiles to face the plasma. All graphite ties have been mounted on heat sink using screw bolts which had been preloaded to produce clamp force. The clamp force is very important to keep the graphite tiles on the surface of the heat sink tightly because the heat flux will cross this contacting surface in a small thermal resistor. Without the clamp force the small gap between graphite tiles and heat sink will lead thermal power cannot be carried away by cooling water. The worse is some bolts turned out with the loss of clamp force. From the mathematical models the process of the loss of clamp force has been studied. Research results explain how the different thermal expansion of three members of the screw joint leads to the clamp force decrease to zero under temperature rise and external force and how the stiffness affect the relationship between the clamp force and temperature. The research also gets the critical temperature point that the clamp force can remain above zero. Research results indicated this screw joint is absolute to lose their clamp force during the EAST running so that the bolt joints should be redesign to improve its reliability.
In this article, the author provides detailed information on a wide variety of commonly used screws, bolts, and other fasteners. The information has been gathered in his engineering career and outside interests (maintenance on his car and airplane, and woodworking). The topic should be of interest to students and educators in many technical…
Lacki, Piotr; Nawrot, Jacek
The work presents a brief description of VFT-WIB® steel-concrete composite beams, examples of composite dowel shear connection shapes are presented. A steel-concrete bridge girder construction solution for the new shape of composite dowel shear connection was proposed. The geometric parameters of the steel section web cutting line are given. For the assumed cross-section dimensions, a numerical model of the girder was made. Numerical analysis was performed, the results of which were compared with the results of the analytical calculations. A program of actions aimed at further optimization of the model is presented.
Sokal, Y. J.; Tyrer, P.
Prestressed concrete girders which are intended for composite construction in bridges and other similar structures are often stored unloaded for some time before being placed in their final positions where top deck is being poured over. During that free storage the girders are subjected to creep and shrinkage which manifests itself through increased upward deformation usually defined as camber. The analytical estimation of this deformation is important as it controls the minimum thickness of the top deck. An attempt was made to correlate on site measurements with continuous computer modeling of the time-dependent behavior using data from recently adopted international standard for concrete structures.
Song, Gangbing; Li, Weijie; Wang, Bo; Ho, Siu Chun Michael
Rock bolts have been widely used as rock reinforcing members in underground coal mine roadways and tunnels. Failures of rock bolts occur as a result of overloading, corrosion, seismic burst and bad grouting, leading to catastrophic economic and personnel losses. Monitoring the health condition of the rock bolts plays an important role in ensuring the safe operation of underground mines. This work presents a brief introduction on the types of rock bolts followed by a comprehensive review of rock bolt monitoring using smart sensors. Smart sensors that are used to assess rock bolt integrity are reviewed to provide a firm perception of the application of smart sensors for enhanced performance and reliability of rock bolts. The most widely used smart sensors for rock bolt monitoring are the piezoelectric sensors and the fiber optic sensors. The methodologies and principles of these smart sensors are reviewed from the point of view of rock bolt integrity monitoring. The applications of smart sensors in monitoring the critical status of rock bolts, such as the axial force, corrosion occurrence, grout quality and resin delamination, are highlighted. In addition, several prototypes or commercially available smart rock bolt devices are also introduced.
Full Text Available The bolting cabin assistance system prevents operators from facing dangerous situations. This system consists of a bolting robot control system and a top view supervisory system. In order to control the bolting robot, circular Hough transforms and fuzzy reasoning are used. First, the circular Hough transform roughly estimates the location of the bolt hole. After that, errors of estimation are compensated for using fuzzy reasoning. In order to track a bolt hole, a region of interest (ROI is used. By setting the region in which to search for a bolt hole, the algorithm tracks the location of the bolt hole. In order to choose an ROI, a template-based matching algorithm is used. In order to make the top view supervisory system, four cameras are installed at the left, right, front and back of the robot. The four individual images from the various cameras are combined to make the top view image after correcting for distortion.
Hatt, C.D.; Reynolds, A.F.; Jeffrey, A.
This paper describes the operational experience gained by British Nuclear Fuels Limited (BNFL) at the THORP spent-fuel storage facility in the application and verification of ultra-sonic bolt seals to light water reactor fuel containers and multielement bottles while in the storage ponds. Additionally, it discusses BNFL's cooperation with the International Atomic Energy Agency, Euratom, and Joint Research Council-Ispra to facilitate the development and design modifications of the remote-handling tools used. Finally, it summarizes the benefits, from an operator's point of view, of using the bolt seals as a safeguards/containment device
The importance of thin-walled box girder bridges has attracted the attention of researchers since the last five decades. A lot of literature has dealt with the analytical formulations as well as experimental investigations. Field studies have increased tremendously in the last decade. So far the agreement between the analytical ...
Virdi, Kuldeep; Azzi, Walid
overhead bracing is not practical. This paper investigates the effect of the U-frame spacing on the stability of the parallel girders. Eigenvalue buckling analysis was undertaken with four different spacings of the U-frames. Results were extracted from finite element analysis, interpreted and conclusions...
Prestressed Concrete (PC) I-girders are used extensively as the primary superstructure components in Texas highway bridges. : A simple semi-empirical equation was developed at the University of Houston (UH) to predict the shear strength of PC I-girde...
In many steel structures like buildings, industrial halls and bridges, standard hot-rolled sections like IPE, HEA, HEB, HEM, HED and UNP in Europe and similar profiles in other regions of the world are used. The range of hot-rolled sections is limited and therefore fabricated plate girders are used
Huynh, T.; Thoft-Christensen, Palle
the flaps is presented. The length of the flaps attached to the girder, the flap configuration and the flap rotational angles are parameters used to increase the critical wind speed of the bridge. To illustrate the theory a numerical example is shown for a suspension bridge of 1000m+2500m+1000m span based...
Bridges are one of the most crucial facilities of transportation networks. Therefore, evaluation of the seismic vulnerability of bridge structures is perpetually regarded topic for researchers. In this study, we developed seismic fragility curves for a continuous steel box girder bridge considering the effect of differentlevels of ...
Kalibhat, Madhusudan G.; Upadhyay, Akhil
Steel concrete composite (SCC) structural system has been commonly used both in the buildings and in the bridges because of the advantages it associates when compared to its counterparts such as RC and steel structures. A typical SCC girder consists of a concrete element placed over a steel element. The effectiveness of this composite system is characterized by the type of connection that exists between the two connecting elements. More commonly shear stud connectors are used to connect the two elements. If the shear studs are infinitely rigid, then it brings about full composite action, on the contrary there is no composite action if the studs are not used, between the two connecting elements. It has been observed that generally the composite action exists somewhere between the full composite action and the no composite action, and is called the partial composite action or the partial interaction. More often the partial composite action is overlooked during the design of SCC girders, and the girder is designed assuming that there exists full composite action, because of the complexities in the analysis incorporating the partial composite action. This might lead to the serviceability issues in the SCC girders. Keeping this in mind the present work has been carried out to understand the significance of the partial interaction in SCC girders. In the present work, a comparative study has been made between the available analytical model and the numerical model. Numerical modeling is performed by using commercially available tool such as SAP2000. The main objective of this work is to bring out the relative significance of the partial interaction with respect to the full composite action, with the help of parametric study. Here, the parametric study has been carried by considering various design parameters, such as, span length, degree of shear connection, cross section geometry of steel girder and concrete slab. It is observed that there is significant increase in
Vugampore, J M V; Bemont, C
Presently costly periodic inspection is vital in guaranteeing the structural integrity of aircraft. This investigation assesses the potential for significantly reducing aircraft maintenance costs without modification of aircraft structures by implementing smart wing bolts, manufactured from TRIP steel, which can be monitored for damage in situ. TRIP steels undergo a transformation from paramagnetic austenite to ferromagnetic martensite during deformation. Subscale smart aircraft wing bolts were manufactured from hot rolled TRIP steel. These wing bolts were used to demonstrate that washers incorporating embedded inductance coils can be utilized to measure the martensitic transformation occurring in the TRIP steel during bolt deformation. Early in situ warning of a critical bolt stress level was thereby facilitated, potentially reducing the costly requirement for periodic wing bolt removal and inspection. The hot rolled TRIP steels that were utilized in these subscale bolts do not however exhibit the mechanical properties required of wing bolt material. Thus warm rolled TRIP steel alloys were also investigated. The mechanical properties of the best warm rolled TRIP steel alloy tested almost matched those of AISI 4340. The warm rolled alloys were also shown to exhibit transformation before yield, allowing for earlier warning when overload occurs. Further work will be required relating to fatigue crack detection, environmental temperature fluctuation and more thorough material characterization. However, present results show that in situ early detection of wing bolt overload is feasible via the use of high alloy warm rolled TRIP steel wing bolts in combination with inductive sensor embedded washers. (paper)
Ostrowski, Krzysztof; Kozłowski, Aleksander
One of the flexibility parameters of semi-rigid joints is rotation capacity. Plastic rotation capacity is especially important in plastic design of framed structures. Current design codes, including Eurocode 3, do not posses procedures enabling designers to obtain value of rotation capacity. In the paper the calculation procedure of the rotation capacity for stiffened bolted flush end-plate beam-to-column connections has been proposed. Theory of experiment design was applied with the use of Hartley's PS/DS-P:Ha3 plan. The analysis was performed with the use of finite element method (ANSYS), based on the numerical experiment plan. The determination of maximal rotation angle was carried out with the use of regression analysis. The main variables analyzed in parametric study were: pitch of the bolt "w" (120-180 mm), the distance between the bolt axis and the beam upper edge cg1 (50-90 mm) and the thickness of the end-plate tp (10-20 mm). Power function was proposed to describe available rotation capacity of the joint. Influence of the particular components on the rotation capacity was also investigated. In the paper a general procedure for determination of rotation capacity was proposed.
Park, Seung Hee; Yun, Chung Bang [Korea Advanced Institute of Science and Technology, Daejeon (Korea, Republic of); Inman, Daniel J. [Virginia Polytechnic Institute and State University, Virginia (United States)
This paper introduces an active sensing node using radio-frequency (RF) telemetry. This device has brought the traditional impedance-based structural health monitoring (SHM) technique to a new paradigm. The RF active sensing node consists of a miniaturized impedance measuring device (AD5933), a microcontroller (ATmega128L), and a radio frequency (RF) transmitter (XBee). A macro-fiber composite (MFC) patch interrogates a host structure by using a self-sensing technique of the miniaturized impedance measuring device. All the process including structural interrogation, data acquisition, signal processing, and damage diagnostic is being performed at the sensor location by the microcontroller. The RF transmitter is used to communicate the current status of the host structure. The feasibility of the proposed SHM strategy is verified through an experimental study inspecting loose bolts in a bolt-jointed aluminum structure
Jang, Myung Guen; Jeong, Jin Hwan; Jang, Yeon Hui; Kim, Hee Cheol; Kim, Jong-Bong [Seoul Nat’l Univ. of Science & Tech, Seoul (Korea, Republic of)
As the size of electric products such as mobile phones and smart watches decrease, the bolts used to assemble these products should also be miniaturized. A miniature-sized bolt has to provide sufficient joining torque and anti-releasing torque to keep the components together. We studied a serrated bolt as a candidate for a miniature-sized fastener to increase the anti-releasing torque. In a serrated bolt, a serrated shape is formed on the bottom surface of the bolt head to create an obstacle to releasing. In this study, finite element analyses for the joining and releasing of bolts were carried out, and the anti-releasing performance was predicted. Based on the results of analyses using various numbers of serrations and fastening depths, the effects of the number of serrations and fastening depth on the anti-releasing performance were investigated.
Jang, Myung Guen; Jeong, Jin Hwan; Jang, Yeon Hui; Kim, Hee Cheol; Kim, Jong-Bong
As the size of electric products such as mobile phones and smart watches decrease, the bolts used to assemble these products should also be miniaturized. A miniature-sized bolt has to provide sufficient joining torque and anti-releasing torque to keep the components together. We studied a serrated bolt as a candidate for a miniature-sized fastener to increase the anti-releasing torque. In a serrated bolt, a serrated shape is formed on the bottom surface of the bolt head to create an obstacle to releasing. In this study, finite element analyses for the joining and releasing of bolts were carried out, and the anti-releasing performance was predicted. Based on the results of analyses using various numbers of serrations and fastening depths, the effects of the number of serrations and fastening depth on the anti-releasing performance were investigated.
Matocha, K.; Wozniak, J. [Vitkovice J.S.C., Ostrava (Switzerland); Pochman, K. [NPP Dukovany (Switzerland)
The susceptibility of CHN35VT-VD and 08CH18N10T stainless steels to stress corrosion cracking in water environment, simulating water solution found in threaded holes, was investigated using rising load line displacement tests of precracked C(T) specimens. To judge the role of oxidant on stress corrosion cracking of both stainless steels, the effect of dissolved oxygen content (fully deaerated water, water aerated at the beginning of the test) was studied. 7 refs.
schematic of equipment for Hopkinson bar data acquisition and high speed capture calibration Figure AC1 1/2- Wheatstone bridge circuit Figure AC2 1/2... Wheatstone bridge Hopkinson incident bar schematic, where numbers in triangles represent pin connection in Ectron 513-2A enclosure Figure AC3 Full... Wheatstone bridge circuit Figure AC4 Full Wheatstone bridge Hopkinson transmission bar and load cell schematic, where numbers in triangles represent
Pollak, S; Reiter, C
Some common types of "humane killers" are supplied with rubber bushings and recoil springs holding back the bolt, which afterwards is rebound into the barrel. Removal of the rubber bush and withdrawal spring before firing can cause the bolt to break and become a free projectile. A suicide case is reported, in which a livestock stunner discharged a steel bolt penetrating the forehead and getting stuck in the skull.
Nielsen, Per Hørlyk; Tesauro, Angelo; Bitsche, Robert
, which create an inner structure in the box girder. With a combination of advanced FEM analysis and the inventions it was possible to reduce the material thickness of the cap by up to 40%. The new design of the box girder was manufactured at SSP Technology A/S, where it was demonstrated......This report is covering the structural design and full scale test of a box girder as a part of the project “Demonstration of new blade design using manufacturing process simulations” supported by the EUDP program. A box girder with a predetermined outer geometry was designed using new inventions...... that the manufacturing process could include the new inventions. Subsequently the box girder was transported to the blade test facility at DTU Wind Energy. A series of test was performed with the blade to investigate the behaviour during loading, and finally the girder was loaded to ultimate failure. The report includes...
Chen, Shi-Zhi; Wu, Gang; Xing, Tuo; Feng, De-Cheng
Monitoring prestressing forces is essential for prestressed concrete box girder bridges. However, the current monitoring methods used for prestressing force were not applicable for a box girder neither because of the sensor’s setup being constrained or shear lag effect not being properly considered. Through combining with the previous analysis model of shear lag effect in the box girder, this paper proposed an indirect monitoring method for on-site determination of prestressing force in a concrete box girder utilizing the distributed long-gauge fiber Bragg grating sensor. The performance of this method was initially verified using numerical simulation for three different distribution forms of prestressing tendons. Then, an experiment involving two concrete box girders was conducted to study the feasibility of this method under different prestressing levels preliminarily. The results of both numerical simulation and lab experiment validated this method’s practicability in a box girder.
Kattimani, Ravi Prasad; Shetty, Sanath; Mirza, Humayun
Introduction: Bolt gun or slaughterer?s guns are used in meat industry for ?humane killing? of animals. Injuries caused by bolt gun are rare, reported exclusively from central European countries. We report a case of 28 year old male, who accidentally shot himself with a bolt gun to his right thigh. Case Report: A 28 years old male presented to our Accident and Emergency department after accidental injury to his right thigh with bolt gun. He had an entry wound measuring 2 cm in length and 1 cm...
Monnet, I.; Decroix, G.M.; Dubuisson, P.; Reuchet, J.; Morlent, O.
In Pressurised Water Reactor, some baffle-former bolts in austenitic stainless steel, are submitted to an important Intergranular cracking. This cracking may be attributed to the irradiation hardening during in pile service. As part of its concern of safety related to the ageing of the plant and, in particular, to the behaviour of the internals, IRSN wished to take part in the expertise Program on CHOOZ A power nuclear plant, within the framework of a convention with EDF, which provided the baffle-bolts. Examinations of these bolts, after 140 000 of in pile service, were carried out by the laboratories of the CEA. Hardness profiles were carried out on four bolts, which were irradiated at different doses, ranging from 0 to 22 dpa. The bolt of the core barrel, considered as unirradiated, shows a constant value of hardness, equal to the value of unirradiated material, all along the bolt and a slight increase in the head of the screw. The axial profile of hardness carried out on an irradiated bolt shows that there is a gradient of hardness between the most irradiated part (400 Hv) and the least irradiated part (270 Hv). The hardness of this bolt starts to evolve at 2.5 dpa and the maximum of hardening is reached for the most irradiated part (3.6 dpa). The hardness profile on the most irradiated bolt (between 10 and 22 dpa) indicate that hardness is homogeneous all along the bolt, 400 Hv. It confirms the existence of a threshold dose beyond which hardness does not vary any more, this threshold is estimated to be between 3.6 dpa and 10 dl Microstructural examinations of these bolts led us to conclude that hardening is correlated to dislocation microstructure. Indeed, the examination of the bolt of the core barrel confirms that this bolt is hardly unirradiated since the initial network of dislocations was not modified and that only some rare dislocation loops were observed. This is in agreement with hardness results showing no hardening of this bolt. On the two more
Jones, Mark Stevens
This thesis investigates the repair of impact-damaged prestressed concrete bridge girders with strand splices and fabric-reinforced cementitious matrix systems, specifically for repair of structural damage to the underside of an overpass bridge girder due to an overheight vehicle collision. Collision damage to bridges can range from minor to catastrophic, potentially requiring repair or replacement of a bridge girder. This thesis investigates the performance of two different types of repair...
Nielsen, Ulrik Dam; Jensen, Jørgen Juncher; Pedersen, Preben Terndrup
Most new advanced ships have extensive data collection systems to be used for continuous monitoring of engine and hull performance, for voyage performance evaluation etc. Such systems could be expanded to include also procedures for stress monitoring and for decision support, where the most...... taking into account whipping stresses. It is conceptually shown how such a method, which integrates onboard estimation of sea states, can be used to deduce decision support with respect to the accumulated fatigue damage in the hull girder.The paper firstly presents a set of measured full-scale wave...... method. This analysis verifies the applied multi-modal spectral analysis procedure for fatigue estimation for cases where hull girder flexibility plays a role.To obtain an automated prediction method for the fatigue damage rates it is in the second part of the paper shown how a combination of the full...
Fujino, T. (Taiheiyo Coal Mining Co. Ltd., Tokyo (Japan))
This paper describes the rock bolt method, devices and construction experiences in maintaining mine roadway drilling with Wombat-type rock bolt drilling and driving machines. Keeping the pace with coal mining zones reaching increasingly greater depths, timbering arch frames have grown larger and heavier, with frame intervals decreased. The described method was adopted to improve work efficiency and save manpowers. The Wombat, 1200-90 machine uses a driving air pressure at 7 kgf/cm[sup 2] a torque at 170 N/m to 180 N/m, and a free rotation at 800 rpm, consumes a r at 60 L/S, weighs 38 kg., and measures 1,370 mm to 3,420 mm in length. The machine is scheduled for use with three gates placed at a depth below sea level as deep as about 600 m, with gate diameters from about 5.0 m to 5.5 m and a length of about 8000 m. Effectiveness and safety of the rock bolts were verified using an extensometer made in the U.S.A. Roof subsidence after a working face has been drilled to 20 m to 30 m was about one third of that when no rock bolts were used, thus the adaptability of the method was verified. Although the drilling technique using the Wombat machine has taken roots at this particular coal mine, problems still remain such as in workability, for which further efficiency improvement and manpower saving are desired. 4 figs., 3 tabs.
Kilian, R.; Devrient, B.; Koenig, G.; Stanislowski, M.; Widera, M.; Beusekom, R. van; Wermelinger, T.
In 2005 intergranular stress corrosion cracking (IGSCC) of barrel bolts was observed in several S/KWU type PWRs. The bolts, known as star bolts, are made of SS type 316 Ti (German Material No. 1.4571 K) bars which are cold worked to adjust the required mechanical properties. This damage mechanism was so far less understood for PWR primary conditions. Therefore an extended joint research program was launched by AREVA GmbH and VGB e.V. to clarify the specific conditions which contributed to the observed findings on barrel bolts. A systematic analysis of the IGSCC affecting parameters as material, heats, environment and mechanical load was performed based on a plant data compilation from all six S/KWU PWRs with comparable core barrel design using barrel and baffle bolts made from type 316Ti. Using the outcome of this systematic data compilation additional computational fluid dynamics calculations in combination with radiolysis calculations were performed. The results showed that by a combination of reduced volume exchange by local flow conditions and radiolysis reactions forming oxidizing species as dissolved oxygen and/or hydrogen peroxide may locally affect the corrosion behavior of cold worked austenitic stainless steels. Therefore, small local volumes with oxidizing water chemistry conditions are assumed to lead to the IGSCC of cold worked type 316Ti. The comparison of the initial cold worked microstructure by TEM with the cold worked and in service irradiated microstructure (void formation, dislocation loop density, etc.) clearly reveals that neutron irradiation hardening in terms of IASCC (Irradiation-Assisted Stress Corrosion Cracking) is not the leading mechanism for these cases of barrel bolt cracking in the analyzed PWRs. (authors)
Hundreds of prestressed concrete girders are used each year for building bridges in Wisconsin. : The prestress transfer from the prestressing strands to concrete takes place at the girder ends. : Characteristic cracks form in this end region during o...
Shatha Dhia Mohammed
Full Text Available This paper presents the application of nonlinear finite element models in the analysis of dapped-ends pre-stressed reinforced concrete girders under static loading by using ANSYS software. The girder dimensions are (4.90 m span, 0.40 m depth, 0.20 m width, 0.20 m nib depth, and 0.10 m nib length and the parameters considered in this research are the pre-stress effect, and strand profile (straight and draped. The numerical results are compared with the experimental results of the same girders. The comparisons are carried out in terms of initial prestress effect, load- deflection curve, and failure load. Good agreement was obtained between the analytical and experimental results. Even that, the numerical model was stiffer than the experimental, but; there were a good agreements in both trends and values. The difference varies in the range (5-12% for the deflection. Results have shown that the pre-stress force has increased the static ultimate load capacity by (35% in case of straight strand and by (97% in case of draped strand
... 21 Food and Drugs 2 2010-04-01 2010-04-01 false Bolted yellow corn meal. 137.280 Section 137.280 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD... definition and standard of identity prescribed by § 137.255 for bolted white corn meal except that cleaned...
... INSPECTION AND CERTIFICATION HUMANE SLAUGHTER OF LIVESTOCK § 313.15 Mechanical; captive bolt. The... under the Act. (a) Application of stunners, required effect; handling. (1) The captive bolt stunners shall be applied to the livestock in accordance with this section so as to produce immediate...
Pedersen, Martin Bo Uhre; Clorius, Christian Odin; Damkilde, Lars
of the residual strength of the glued-in bolts that served as the blade to rotor hub connection in the windmill. The load history of the bolts, the test method, the observed fracture modes and the force displacement curves are presented along with the recorded residual strength of the bolts. The bolts...... with a length of 500 mm had a special hollow tapering giving them a higher load bearing capacity than solid bolts of equal dimensions. A FEM-analysis confirms the higher load bearing capacity. The mean residual strength was found to be 362 kN with a standard deviation of 37 kN, which is 95% of the predicted...
Nameer A. Alawsh
Full Text Available In this paper, the general behavior of reinforced concrete hybrid box girders is studied by experimental and numerical investigation. Experimental work is included casting monolithically five specimens of box girders with trapezoidal cross section and testing it as simply supported under two point loading. Two specimens were cast as homogenous box girders (full normal strength concrete (NSC (about 35 MPa and full high strength concrete (HSC (about 55 MPa and three specimens were cast as hybrid box girders (HSC in upper flange only, HSC in upper flange and half depth of webs, and HSC in bottom flange and total depth of webs. Experimental results showed significant effects of concrete hybridization on the structural behavior of box girders specimens such as: cracking loads, cracking patterns, ultimate strengths, and failure modes. The ultimate strength of Hybrid box girders increased by 23% as average when compared with the homogenous box girder (full NSC and decreased by 9% as average when compared with homogenous box girder (full HSC. In numerical investigation, the tested specimens were modeled and analyzed using three dimensional non-linear finite element analysis. The analysis was carried out by using a computer program (ANSYS V16.1. The numerical results showed an acceptable agreement with the experimental work with difference about (3.12% and 9.588% as average for ultimate load and deflection, respectively.
Project 0-5574 Curved Plate Girder Design for Safe and Economical Construction, resulted in the : development of two design tools, UT Lift and UT Bridge. UT Lift is a spreadsheet-based program for analyzing : steel girders during lifting while ...
Suangga, Made; Hidayat, Irpan; Lutter, Bobby
PCI bridge girders is known and widely used for many construction e.g.: bridge, wharf, flyover, and other application. PC Bridge girders have two types: Pre - tensioned girders and post - tensioned girders. In pre tensioned girders, prestressing in carried out first then after that the fresh concrete poured. The prestressing process in only carried off after the concrete has sufficient strength. In this study, analysis was conducted for PCI bridge girder with span is 40 meters. Based on the data geometry bridge dimension girder, material girder, and material strands cable, it will be analyzed to calculate the natural frequencies and moment capacity using finite element program (Midas/Civil program). So it can be estimated how much the percentage reduction prestress force on the bridge until PCI bridge structure collapses. From the calculation, it found that the pattern comparison between reduction prestressing force and natural frequency are linear. These results are also similar for natural frequency versus moment capacity.PCI bridge will collapse when the reduction prestreesing force of 45 % to 50 % from the total loss of prestressing.
Nielsen, Per H.; Tesauro, A.; Bitsche, R. [Technical Univ. of Denmark. DTU Wind Energy, DTU Risoe Campus, Roskilde (Denmark)] [and others
This report is covering the structural design and full scale test of a box girder as a part of the project ''Demonstration of new blade design using manufacturing process simulations'' supported by the EUDP program. A box girder with a predetermined outer geometry was designed using new inventions, which create an inner structure in the box girder. With a combination of advanced FEM analysis and the inventions it was possible to reduce the material thickness of the cap by up to 40%. The new design of the box girder was manufactured at SSP Technology A/S, where it was demonstrated that the manufacturing process could include the new inventions. Subsequently the box girder was transported to the blade test facility at DTU Wind Energy. A series of test was performed with the blade to investigate the behaviour during loading, and finally the girder was loaded to ultimate failure. The report includes the description of the test setup, the test and an overview over the results from the test performed on the box girder. During the final test the box girder failed at 58 % of the expected ultimate load. Unfortunately, no definite conclusion could be made concerning the failure mechanism. (Author)
Precast/prestressed concrete girders are commonly used in bridge construction in the United States. The application and diffusion of the prestress force in a pretensioned girder cause a vertical tension force to develop near the end of the beam. Fiel...
Nigerian Journal of Technology,. Vol. 34, No. 1, January 2015 87 bridges under the attack of pitting corrosion. Savkovic et al.  proposed an optimum solution to optimization of the box section of the main girder of the bridge crane. Reduction of the girder mass was set as the objective function. Optimum dimensions of the.
Arnandha, Yudhi; Satyarno, Iman; Awaludin, Ali; Irawati, Inggar Septia; Ihsan, Muhamad; Wijanarko, Felyx Biondy; William, Mahdinur, Fardhani, Arfiati
Wood-plastic composite (WPC) is a relatively new material that consists of sawdust and plastic polymer using the extrusion process. Due to its attributes such as low water content, low maintenance, UV durability and being fungi and termite resistant. Nowadays, WPC has already been produced in Indonesia using sawdust from local wood such as Albizia (Paraserianthes falcataria) and Teak (Tectona grandis). Moreover preliminary studies about the physical and mechanical WPC board from Albizia sawdust and HDPE plastic have been carried out. Based on these studies, WPC has a high shear strength around 25-30 MPa higher than its original wood shear strength. This paper was a part of the research in evaluating WPC as potential sheathing in a shear wall system. Since still little is known about connection behavior in WPC using Indonesian local wood, this study evaluated the connection for both of these two types of wood-plastic composite. WPC board from Albizia sawdust will be projected as shear wall sheathing and WPC stud from Teak sawdust projected to be shear wall frame. For this study, the embedding strength for both WPC was determined according to ASTM D 5764 standard, using two types of bolts (stainless bolt and standard bolt) with several diameters as variation (6 mm, 8 mm, 10 and 12 mm). Hence, dowel-bearing test under fastened condition conducted accordance to ASTM D5652, hereby the yield strength then compared with the prediction yield strength from European Yield Model (EYM). According to both single and double shear connection, it can be concluded that yield strength from the EYM method tended to under-predict the 5% diameter offset yield than the actual yield strength from the test. The yield strength itself increase with the increase of bolt diameter. For single shear connection, the highest yield strength was 12 mm standard bolt around 9732 N, slightly higher than stainless bolt around 9393 N. Whereby for double shear connection, the highest yield strength was
Bolts connecting collector bodies with lids were the first components of steam generators at Czechoslovak WWER-440 units on which corrosion damage was observed in 1982 to 1983. Corrosion cracks developed particularly in the cylindrical parts of the bolts. This was due to intergranular corrosion caused by the unsuitable chemical composition of the steel used, by secondary water level fluctuations, by the surrounding environment of the bolts being unamenable to deaeration, as well as by inappropriate tightening of the bolts which gave rise to additional deformation stress. Steps were taken to eliminate all these drawbacks, and owing to this the corrosion cracking of the bolts was prevented for longer than 6 years. Cracks were observed again in 1989; they occurred then not only in the cylindrical parts but also in the thread parts of the bolts. The corrosion was again of intergranular nature. As yet, the cause of the corrosion cracking of the bolts is not unambiguously known. It is largely assumed that the material used, viz. the high-strength KhN35VT nickel alloy, is exceedingly sensitive to the working procedure and to stress. (Z.M.)
The article presents different types of rock bolt support used in Polish ore mining. Individual point resin and expansion rock bolt support were characterized. The roof classes for zinc and lead and copper ore mines were presented. Furthermore, in the article laboratory tests of point resin rock bolt support in a geometric scale of 1:1 with minimal fixing length of 0.6 m were made. Static testing of point resin rock bolt support were carried out on a laboratory test facility of Department of Underground Mining which simulate mine conditions for Polish ore and hard coal mining. Laboratory tests of point resin bolts were carried out, especially for the ZGH Bolesław, zinc and lead "Olkusz - Pomorzany" mine. The primary aim of the research was to check whether at the anchoring point length of 0.6 m by means of one and a half resin cartridge, the type bolt "Olkusz - 20A" is able to overcome the load.The second purpose of the study was to obtain load - displacement characteristic with determination of the elastic and plastic range of the bolt. For the best simulation of mine conditions the station steel cylinders with an external diameter of 0.1 m and a length of 0.6 m with a core of rock from the roof of the underground excavations were used.
Hébrard, Claire; Peterson, Daniel G; Willems, Glenda; Delaunay, Alain; Jesson, Béline; Lefèbvre, Marc; Barnes, Steve; Maury, Stéphane
In sugar beet (Beta vulgaris altissima), bolting tolerance is an essential agronomic trait reflecting the bolting response of genotypes after vernalization. Genes involved in induction of sugar beet bolting have now been identified, and evidence suggests that epigenetic factors are involved in their control. Indeed, the time course and amplitude of DNA methylation variations in the shoot apical meristem have been shown to be critical in inducing sugar beet bolting, and a few functional targets of DNA methylation during vernalization have been identified. However, molecular mechanisms controlling bolting tolerance levels among genotypes are still poorly understood. Here, gene expression and DNA methylation profiles were compared in shoot apical meristems of three bolting-resistant and three bolting-sensitive genotypes after vernalization. Using Cot fractionation followed by 454 sequencing of the isolated low-copy DNA, 6231 contigs were obtained that were used along with public sugar beet DNA sequences to design custom Agilent microarrays for expression (56k) and methylation (244k) analyses. A total of 169 differentially expressed genes and 111 differentially methylated regions were identified between resistant and sensitive vernalized genotypes. Fourteen sequences were both differentially expressed and differentially methylated, with a negative correlation between their methylation and expression levels. Genes involved in cold perception, phytohormone signalling, and flowering induction were over-represented and collectively represent an integrative gene network from environmental perception to bolting induction. Altogether, the data suggest that the genotype-dependent control of DNA methylation and expression of an integrative gene network participate in bolting tolerance in sugar beet, opening up perspectives for crop improvement. © The Author 2015. Published by Oxford University Press on behalf of the Society for Experimental Biology.
Pedersen, Niels Leergaard; Pedersen, Pauli
and the plate is extended by the possibility of designing a gap, that is, a nonuniform distance between the bolt and plate before prestressing. Designing the gap function generates the possibility for a better stress field by which the stiffness of the bolt is lowered, and at the same time the stiffness...... of the members is increased. Both of these changes have a positive influence on the lifetime of the connections. From designing a varying gap size distribution, it is found that the stiffness become a function of the loading. It is shown that similar improvements in the stiffness ratio between the bolt...
Stone, W. C.; Breen, J. E.
Several large thin-webbed box girders, with post-tensioned anchorage zones experienced large cracks along the tendon path in the anchorage zones at the design stressing load. Cracking provides a path for penetration of moisture and salts and thus presents a potential corrosion and frost damage threat. Such cracking negates the use of prestressed concretes. An extensive literature review which documents the state of the art in anchorage zone analysis behavior, and design recommendations is summarized. The general utilization of a three dimensional finite element program, PUZGAP3D, for analysis of the complex anchorage zone region is outlined. The program was used to study straight and curved tendon paths.
Full Text Available Girder is an important part of the bridge crane, which is also the main force element. In order to prevent accidents, it is necessary to collect the bridge crane girder stress data to analyse the fatigue life. This paper constructs a bridge crane girder strain acquisition system. The hardware system consists of sensors, connectors, data acquisition cards, wireless data transmission groups, POE power and host computer. The software system consists of NI MAX to interface with the computer's NI hardware and software resources,and LabVIEW programming to display and storage the girder strain data. Through this system, positions and working days strain data acquisition for the 50/10 t bridge crane girder gets the key positions strain data. The results show that the girder strain data acquisition system runs stably, channel signals of acquisition task transmit accurately, and the terminal data stores competely, meeting the detection requirements, which provides an important data support for the subsequent fatigue analysis and accurate remaining service life prediction of the crane girder.
Chen, S. H.; Yang, Z. M.; Wang, W. M.; Shahrour, I.
In this article, the rock bolt reinforcement mechanism is discussed, and the gravity method as well as the finite element method for the bolted rock is presented. These methods are applied to study the gravity dam foundation of the Xiaoxi Hydropower Project, which is influenced by the presence of a large fault with a cracked zone over 180 m wide. Rock bolt reinforcement was used to improve the stability of the dam foundation, and the reinforcement parameters were determined from a semi-empirical equation controlled by in situ test. The stability analysis was conducted using the above methods, and the improvement in terms of deformation and stress as well as stability of the dam foundation due to the reinforcement is assessed. Rock bolt reinforcement was completed successfully, and the dam started normal operations in January 2008.
The current means and methods of verifying that high-strength bolts have been properly tightened are very laborious and time : consuming. In some cases, the techniques require special equipment and, in other cases, the verification itself may be some...
Kim, Jong-Wook; Lee, Gyu-Mahn; Jeoung, Kyeong-Hoon; Kim, Tae-Wan; Park, Keun-Bae; Kim, Keung-Koo
The reactor pressure vessel flange is welded to the upper part of reactor pressure vessel, and there are stud holes to mount the closure head with stud bolts. The surface mating the closure head is compressed with O-ring, which acts as a sealing gasket to prevent coolant leakage. Bolted flange connections perform a very important structural role in the design of a reactor pressure vessel. Their importance stems from two important functions: (a) maintenance of the structural integrity of the connection itself, and (b) prevention of leakage through the O-ring preloaded by stud bolts. In the present study, an evaluation procedure for the design of stud bolt is developed to meet ASME code requirements. The developed design procedure could provide typical references in the development of advanced reactor design in the future
National Aeronautics and Space Administration — A concept is proposed for monitoring bolt preload that offers accuracy and low-cost features not available in existing preload monitoring systems. Existing washer...
Mills, S.F.; Loving, A.B.
With over 2500 bolting operations to perform remotely, the selection of appropriate tooling was fundamental to the efficiency of the recent JET Divertor Exchange. During mock-up trials using the Mascot force reflecting manipulator it became apparent that many traditional manual techniques were inappropriate. Hence, it was necessary to design special bolting tools to satisfy the remote handling needs. This paper discusses the evolution of this tooling. (authors)
Bournine, H.; Wagg, D.J.; Neild, S.A.
In this paper we examine the use of dynamic friction within a bolted structure to improve damping properties of the structure. The structure considered for this paper consists of two steel beam-columns bolted together allowing dynamic friction to occur at the interface. This paper presents an analysis of the behaviour of the structure and the effect of friction on its dynamics. It also presents an analysis of the energy dissipation in the structure by means of friction and the optimization of...
Kattimani, Ravi Prasad; Shetty, Sanath; Mirza, Humayun
Bolt gun or slaughterer's guns are used in meat industry for "humane killing" of animals. Injuries caused by bolt gun are rare, reported exclusively from central European countries. We report a case of 28 year old male, who accidentally shot himself with a bolt gun to his right thigh. A 28 years old male presented to our Accident and Emergency department after accidental injury to his right thigh with bolt gun. He had an entry wound measuring 2 cm in length and 1 cm in breadth over anterior aspect of lower one third of thigh at lower and sustained Grade II compound fracture of right femur shaft at distal one third. The wound was treated with multiple debridements, negative pressure wound therapy and intravenous antibiotics based on culture and sensitivity. Bolt gun or slaughterer's guns are weapons used in meat industry for slaughtering animals. Wounds inflicted by bolt guns have specific morphological feature, distinctive from wounds made by other kinds of hand firearms. Most of the time wound will be infected at presentation. Lesions caused by these weapons are likely to have a more serious character than is to be expected from the size of the entrance wound. The mainstay of treatment is liberal wound exploration, multiple debridement's and intra venous antibiotics based on culture reports to treat infection and prevent morbidity.
Pfeiffer, Nina; Tränkner, Conny; Lemnian, Ioana; Grosse, Ivo; Müller, Andreas E; Jung, Christian; Kopisch-Obuch, Friedrich J
This study reveals for the first time a major QTL for post-winter bolting resistance in sugar beet ( Beta vulgaris L.). The knowledge of this QTL is a major contribution towards the development of a winter sugar beet with controlled bolting behavior. In cool temperate climates, sugar beets are currently grown as a spring crop. They are sown in spring and harvested in autumn. Growing sugar beet as a winter crop with an extended vegetation period fails due to bolting after winter. Bolting after winter might be controlled by accumulating genes for post-winter bolting resistance. Previously, we had observed in field experiments a low post-winter bolting rate of 0.5 for sugar beet accession BETA 1773. This accession was crossed with a biennial sugar beet with regular bolting behavior to develop a F3 mapping population. The population was grown in the greenhouse, exposed to artificial cold treatment for 16 weeks and transplanted to the field. Bolting was recorded twice a week from May until October. Post-winter bolting behavior was assessed by two different factors, bolting delay (determined as days to bolt after cold treatment) and post-winter bolting resistance (bolting rate after winter). For days to bolt, means of F3 families ranged from 25 to 164 days while for bolting rate F3 families ranged from 0 to 1. For each factor one QTL explaining about 65% of the phenotypic variation was mapped to the same region on linkage group 9 with a partially recessive allele increasing bolting delay and post-winter bolting resistance. The results are discussed in relation to the potential use of marker-assisted breeding of winter sugar beets with controlled bolting.
This report describes research conducted to enable evaluation of existing vintage bent cap beams in reinforced concrete : deck girder bridges. The report is organized into two parts: 1) flexural anchorage capacity response and prediction of : reduced...
This report describes research conducted to enable evaluation of existing vintage bent cap beams in reinforced concrete : deck girder bridges. The report is organized into two parts: 1) flexural anchorage capacity response and prediction of : reduced...
This report presents the research conducted as part of an investigation for the California Department of Transportation (Caltrans) regarding the seismic response and overall moment capacity of precast I-girder to inverted-T bent cap bridge connection...
The use of high performance concretes to provide longer bridge spans has been limited due to the capacity of existing infrastructure to handle the load of the girders during transportation. The use of High Strength Lightweight Concrete (HSLW) can pro...
The Texas Department of Transportation (TxDOT) is currently designing typical highway bridge structures as simply supported using standard precast, pretensioned girders. TxDOT is interested in developing additional economical design alternatives for ...
The goal of everyone in the transportation community is to build bridges : that are economic, easy to construct, and durable. Therefore, accelerating : bridge construction through the use of precast concrete or prefabricated : steel girders is a comm...
The objectives of the research were (1) to provide assurance that full size, deep prestressed concrete girders made with HPC would perform satisfactorily under flexural fatigue, static shear, and static flexural loading conditions; (2) to determine i...
Continuity diaphragms used on skewed bents in prestressed girder bridges cause difficulties in detailing and : construction. Details for bridges with large diaphragm skew angles (>30) have not been a problem for LA DOTD. : However, as the skew angl...
The Texas Department of Transportation designs typical highway bridge structures as simple span systems using : standard precast, pretensioned girders. Spans are limited to about 150 ft due to weight and length restrictions on : transporting the prec...
The study presented focuses on the development of a novel timber joint. Traditional timber joints with mechanical fasteners, particular dowel type fasteners, such as bolts exhibit a low strength and an unreliable stiffness and ductility caused by the presence of hole clearance and the unpredictable
Newhouse, Charles David
Over the past fifty years, many states have recognized the benefits of making precast, prestressed multi-girder bridges continuous by connecting the girders with a continuity diaphragm. Although there is widespread agreement on the benefits of continuous construction, there has not been as much agreement on either the methods used for design of these systems or the details used for the continuity connections. To aid designers in choosing the most appropriate method, an analytical and...
Full Text Available Distortional buckling is one of the most important buckling modes of the steel-concrete composite girder under negative moment. In this study, the equivalent lateral and torsional restraints of the bottom flange of a steel-concrete composite girder under negative moments due to variable axial forces are thoroughly investigated. The results show that there is a coupling effect between the applied forces and the lateral and torsional restraint of the bottom flange. Based on the calculation formula of lateral and torsional restraints, the critical buckling stress of I-steel-concrete composite girders and steel-concrete composite box girders under variable axial force is obtained. The critical bending moment of the steel-concrete composite girders can be further calculated. Compared to the traditional calculation methods of elastic foundation beam, the paper introduces an improved method, which considers coupling effect of the external loads and the foundation spring constraints of the bottom flange. Fifteen examples of the steel-concrete composite girders in different conditions are calculated. The calculation results show a good match between the hand calculation and the ANSYS finite element method, which validated that the analytic calculation method proposed in this paper is practical.
Full Text Available Patch loading is a predominant load case at incremental bridge launching. Bridge girder webs are frequently provided with longitudinal stiffeners to increase in-service shear and bending strength, and its effect has been included in design codes. However, no straightforward rules are given to account for the influence of such stiffeners on improving the patch loading resistance. This paper presents a review of some available formulae found in the literature to estimate the girder ultimate strength including the provisions of the European, American and Colombian design codes. Additionally, a nonlinear finite element analysis is conducted on three case studies related to actual launched bridges. The case studies are also used to study the influence of the longitudinal stiffener and girder depth on the girder capacity. Different load-displacement responses are observed depending on the girder depth. Finally, the finite element analysis shows to what extent the longitudinal stiffeners can increase the patch loading capacity of bridge girder webs during launching.
Full Text Available This paper represents the finite element results for the local buckling of tapered plate girders subjected to combine pure bending and shear stresses. An idealized model is developed representing the loading of the tapered panel that generates uniform normal stresses due to flexure, or uniform and constant shear stresses in the case of shear. Eigen-value analysis was performed for several tapered web plate girders that have different geometric parameters. A parametric study is made to reduce the FE model size showing the effect of decreasing the tapered panel adjacent straight panels, maintaining the same result accuracy as a complete girder model. The combined buckling capacity of bending and shear is determined by applying all possible load pattern combinations, together with different interaction ratios. An analysis study is presented to investigate the effect of the tapering angle on the combined bending–shear capacity of the girder. The study also includes the effect of the flange and web slenderness on the local buckling of the girder. Considering residual stresses as part of the loading stresses, the analysis procedure is repeated for some cases, and the effect of combining of the residual stresses together with the external loads is found. Empirical approximate formulae are given to estimate the combined flexure–shear buckling resistance of the tapered girder safely.
Tiwari, Sanjay; Bhargava, Pradeep
Cellular steel section composite with a concrete deck is one of the most suitable superstructures in resisting torsional and warping effects induced by highway loading. This type of structure has inherently created new design problems for engineers in estimating its load distribution when subjected to moving vehicles. Indian Codes of Practice does not provide any specific guidelines for the design of straight composite concrete deck-steel multi-cell bridges. To meet the practical requirements arising during the design process, a simple design method is needed for straight composite multi-cell bridges in the form of load distribution factors for moment and shear. This work presents load distribution characteristics of straight composite multi-cell box girder bridges under IRC trains of loads.
Akhnoukh, Amin K.
Demand continues to increase for bridges with long spans and shallow depths. Due to safety concerns, four-span overpasses are being replaced with two span overpasses to avoid placement of piers near the highway shoulders. In the meantime, the bridge profile is restricted due to existing businesses nearby. Thus, nearly the same superstructure depth must be used for double the span length. This dissertation focuses on topics aiming at providing precast prestressed concrete girders with the shallowest possible depth for a given span. It forms parts of larger projects conducted by the University of Nebraska for the Nebraska Department of Roads and for the Wire Reinforcement Institute. Specifically, the following issues were researched: (1) Use of 0.7 in. diameter Grade 270 ksi strands for pretensioning of precast concrete girders at a strand spacing of 2 inches by 2 inches. This arrangement gives nearly 190 percent of the prestressing with 0.5 in. diameter strands and nearly 135 percent with 0.6 in. strands. The research focuses on the required confinement steel to allow determination of transfer and development lengths according to current procedures in the AASHTO LRFD Bridge Design Specifications for smaller strands. (2) Develop a self consolidating concrete (SCC) mix, using Nebraska aggregates that will allow for a specified design strength at service of 15 ksi and a minimum strength at one day of 10 ksi, representing the demand at the time of release of the prestress to the concrete member. Prior to this study, standard concrete strength prevailing in Nebraska has been 8 ksi at service and 6.5 ksi at release. It was the goal of the research to keep the cost of materials as low as possible but not exceeding 250 per cubic yard, compared to the proprietary mixes that cost approximately four times this amount. (3) Use of 80 ksi welded wire reinforcement (WWR) as the auxiliary reinforcement for shear, web end splitting and flange confinement. This would result in higher
Eom, Gi-Ha; Kim, Sung Jae; Lee, Tae-Hee; Kim, Jang-Ho Jay
A recent trend in bridge construction has been the optimization of the cost-to-performance ratio. The most effective way to optimize the cost-to-performance ratio is to maximize the efficiency of the superstructure. Currently, many bridge engineers and designers favor two- or three- girder plate superstructures, due to their cost advantages. However, research on the performance enhancements of the I-type girder in two- or three- girder plate bridges is lacking. One of the most important performance improvement technologies for the I-type girder is the "preflex" method. In the preflex method, the specimen is inverted during the construction process to apply prestressed cambering to the specimen by using self-weight. However, a problem with the preflex construction method is difficulty with inverting the girder/plate system during the concrete curing process. Therefore, a new inverting system called Turn-Over (TO) wheel was proposed. Using TO wheels, wider variations to the I-type girder design can be achieved. Using this TO construction method, various cross sectional designs of girder plate systems can be considered due to its easiness in inverting the girder/plate system. In this study, the location of concrete confinement sections between the steel I-beams and concrete plates was varied in an I-girder cross-sectional design. Design parameters included effective height, flange thickness, flange width, confining concrete section width, etc. From this study, the optimum cross-sectional design of the I-girder/concrete plate system was achieved. Then, a single 20 m TO girder/plate system and two 20 m TO girder bridges were constructed and tested to evaluate their performance. From the test, failure behavior, load carrying capacity, crack pattern, etc., are obtained. The results are discussed in detail in this paper.
Zhou Danfeng; Wang Lianchun; Li Jie; Yu Peichang
The maglev vehicle-girder coupled vibration problem has been encountered in many maglev test or commercial lines, which significantly degrade the performance of the maglev train. In previous research on the principle of the coupled vibration problem, it has been discovered that the fundamental model of the maglev girder can be simplified as a series of mass-spring resonators of different but related resonance frequencies, and that the stability of the vehicle-girder coupled system can be inve...
Full Text Available A recent trend in bridge construction has been the optimization of the cost-to-performance ratio. The most effective way to optimize the cost-to-performance ratio is to maximize the efficiency of the superstructure. Currently, many bridge engineers and designers favor two- or three- girder plate superstructures, due to their cost advantages. However, research on the performance enhancements of the I-type girder in two- or three- girder plate bridges is lacking. One of the most important performance improvement technologies for the I-type girder is the “preflex” method. In the preflex method, the specimen is inverted during the construction process to apply prestressed cambering to the specimen by using self-weight. However, a problem with the preflex construction method is difficulty with inverting the girder/plate system during the concrete curing process. Therefore, a new inverting system called Turn-Over (TO wheel was proposed. Using TO wheels, wider variations to the I-type girder design can be achieved. Using this TO construction method, various cross sectional designs of girder plate systems can be considered due to its easiness in inverting the girder/plate system. In this study, the location of concrete confinement sections between the steel I-beams and concrete plates was varied in an I-girder cross-sectional design. Design parameters included effective height, flange thickness, flange width, confining concrete section width, etc. From this study, the optimum cross-sectional design of the I-girder/concrete plate system was achieved. Then, a single 20 m TO girder/plate system and two 20 m TO girder bridges were constructed and tested to evaluate their performance. From the test, failure behavior, load carrying capacity, crack pattern, etc., are obtained. The results are discussed in detail in this paper.
Gazis, Nikolaos; Mainaud-Durand, Hélène; Samochkine, Alexandre; Anastasopoulos, Michail
The Compact LInear Collider (CLIC), currently under study at CERN, aims at the development of a Multi-TeV e+ e- collider. The micro-precision CLIC RF-structures will have an accelerating gradient of 100 MV/m and will be mounted and aligned on specially developed supporting girders. The girder fabrication constraints are dictated by stringent physics requirements. The micrometric pre-alignment over several kilometers of girders, allow for the CLIC structures to fulfill their acceleration and collision functionality. Study of such girders and their sophisticated alignment method, is a challenging case involving dedicated mechanical design as well as prototype production and experimental testing.
Hou, Tsung-Chin; Gao, Wei-Yuan; Chang, Chia-Sheng; Zhu, Guan-Rong; Su, Yu-Min
The three-span steel-arch-steel-girder Jiaxian Bridge was newly constructed in 2010 to replace the former one that has been destroyed by Typhoon Sinlaku (2008, Taiwan). It was designed and built to continue the domestic service requirement, as well as to improve the tourism business of the Kaohsiung city government, Taiwan. This study aimed at establishing the baseline model of Jiaxian Bridge for hazardous scenario simulation such as typhoons, floods and earthquakes. Necessities of these precaution works were attributed to the inherent vulnerability of the sites: near fault and river cross. The uncalibrated baseline bridge model was built with structural finite element in accordance with the blueprints. Ambient vibration measurements were performed repeatedly to acquire the elastic dynamic characteristics of the bridge structure. Two frequency domain system identification algorithms were employed to extract the measured operational modal parameters. Modal shapes, frequencies, and modal assurance criteria (MAC) were configured as the fitting targets so as to calibrate/update the structural parameters of the baseline model. It has been recognized that different types of structural parameters contribute distinguishably to the fitting targets, as this study has similarly explored. For steel-arch-steel-girder bridges in particular this case, joint rigidity of the steel components was found to be dominant while material properties and section geometries relatively minor. The updated model was capable of providing more rational elastic responses of the bridge superstructure under normal service conditions as well as hazardous scenarios, and can be used for manage the health conditions of the bridge structure.
The majority of highway bridges are built as cast-in-place reinforced concrete slabs and prestressed concrete : girders. The simple-span precast, prestressed concrete girders made continuous through cast-in-place decks : and diaphragms have been wide...
Kh. M. Muselemov
Full Text Available Objectives. The aim of the present work is to study the influence of design parameters on the stress-deformed state of a sprengel crane girder; to compile the tables and corresponding graphs illustrating changes in internal force factors in the characteristic cross-sections of the system elements under consideration. The article describes the study of the stress-deformed state (SDS of a metal strut-framed crane girder.Methods. Numerical methods of analysis based on the use of the Green's function are used during solving this problem. A dimensionless parameter is introduced, depending on which the tables and graphs are constructed. According to the known algorithm, the calculations of internal force factors in the sections of the considered construction are performed.Results. Depending on the dimensionless parameter characterising the geometry and physical features of the system, tables of bending moments and transverse forces are compiled. According to these tables, the appropriate graphs are plotted in order to choose easily the optimal design parameters.Conclusion. The dependence of the moments and transverse forces on the dimensionless parameter k was found, the corresponding graphs were plotted and the metal costs for the girders were calculated. The minimum values of the moments and transverse forces are established to take place when the dimensionless parameter k values are close to zero. The most economical was a strut-framed crane girder having k = 0.0001. The most uneconomical had k = 0.05 and k =∞. Eventually, the sprengel girders were found to be more profitable as compared to conventional crane girders. In the examples considered in the article, the metal savings amounted up to 14%. The presented methodology allows the calculation and designing of strut-framed crane girders with two racks to be carried out.
Full Text Available Bridges have an important role in impacting the civilization, growth and economy of cities from ancient time until these days due to their function in reducing transportation cost and time. Therefore, development of bridges has been a knowledge domain in civil engineering studies in terms of their types and construction materials to confirm a reliable, safe, economic design and construction. Girder-bridge of concrete deck and I-beam girder has been used widely for short and medium span bridges because of ease and low-cost of fabrication. However, many theoretical and practical investigations are still undertaken regarding the type of beam girder; i.e steel composite or prestressed concrete. This paper evaluates the effect of bridge span and the type of girder on the capital cost and life cycle costs of bridges. Three types of girders were investigated in this research: steel composite, pre-tensioned pre-stressed concrete and post-tensioned pre-stressed concrete. The structural design was analyzed for 5 span lengths: 20, 25, 30, 35 and 40m. Then, the capital construction cost was accounted for 15 bridges according to each span and construction materials. Moreover, the maintenance required for 50 years of bridge life was evaluated and built up as whole life costs for each bridge. As a result of this study, the influence of both span length and type of girder on initial construction cost and maintenance whole life costs were assessed to support the decision makers and designers in the selection process for the optimum solution of girder bridges.
Borjen Yeh; Douglas Rammer; Jeff Linville
The design of multiple bolted connections in accordance with Appendix E of the National Design Specification for Wood Construction (NDS) has incorporated provisions for evaluating localized member failure modes of row and group tear-out when the connections are closely spaced. Originally based on structural glued laminated timber (glulam) members made with all L1...
Dec 15, 2013 ... Keywords: State-building, social capital, ethnic supremacy, Dinka, Nuer,. South Sudan. * Robert Gerenge is the Head of Special Programmes at the Electoral Institute for Sustainable. Democracy in Africa (EISA). South Sudan's December 2013 conflict: Bolting state-building fault lines with social capital.
Syd S. Peng
Roof bolting is the most popular method for underground openings in the mining industry, especially in the bedded deposits such as coal. In fact, all U.S. underground coal mine entries are roof-bolted as required by law. However, roof falls still occur frequently in the roof bolted entries. The two possible reasons are: the lack of knowledge of and technology to detect the roof geological conditions in advance of mining, and lack of roof bolting design criteria for modern roof bolting systems. This research is to develop a method for predicting the roof geology and stability condition in real time during roof bolting operation. Based on this information, roof bolting design criteria for modern roof bolting systems will be developed for implementation in real time. For the prediction of roof geology and stability condition in real time, a micro processor was used and a program developed to monitor and record the drilling parameters of roof bolter. These parameters include feed pressure, feed flow (penetration rate), rotation pressure, rotation rate, vacuum pressure, oil temperature of hydraulic circuit, and signals for controlling machine. From the results of a series of laboratory and underground tests so far, feed pressure is found to be a good indicator for identifying the voids/fractures and estimating the roof rock strength. The method for determining quantitatively the location and the size of void/fracture and estimating the roof rock strength from the drilling parameters of roof bolter was developed. Also, a set of computational rules has been developed for in-mine roof using measured roof drilling parameters and implemented in MRGIS (Mine Roof Geology Information System), a software package developed to allow mine engineers to make use of the large amount of roof drilling parameters for predicting roof geology properties automatically. For the development of roof bolting criteria, finite element models were developed for tensioned and fully grouted bolting
Full Text Available The impact on curved box-girder bridges due to vehicle moving across rough bridge deck have been analyzed using bridge-vehicle coupled dynamics. The bridge deck unevenness has been assumed to be a homogeneous random process in space specified by a PSD function. The analysis incorporates the effect of centrifugal forces due to vehicle moving on curved bridge. The curved box-girder bridge has been numerically modeled using computationally efficient thin-walled box-beam finite elements which take into account the torsional warping, distortion and distortional warping, that are important features of thin-walled box girders. Rigid vehicle with longitudinal and transverse input to the wheels giving rise to heave-pitch-roll degrees of freedom has been considered. The theoretical bridge model used in simulation study has been validated by a free vibration experiment using impact excitation. The impact factors for several response parameters such as bending moment, shear force, torsional moment, torsional bi-moment, distortional moment, distortional bi-moment and vertical deflections have been obtained for various bridge-vehicle parameters. Both constant velocity and forward acceleration of the vehicle have been considered to examine impact factor. The results highlighted that the impact factors of a curved box girder bridge corresponding to torsion, distortion and their corresponding bimoments have been observed to be generally very high, while those of the other responses are also relatively higher than that of corresponding straight box girder bridge.
Full Text Available The steel-concrete composite girder has been usually applied in the bridge and building structures, mostly consisting of concrete slab, steel girder, and shear connector. The current fatigue damage assessment for the composite girder is largely based on the strain values and concrete crack features, which is time consuming and not stable. Hence the vibration-based fatigue damage assessment has been considered in this study. In detail, a steel-steel fiber reinforced concrete (SFRC composite girder was tested. The steel fiber reinforced concrete is usually considered for dealing with the concrete cracks in engineering practice. The composite girder was 3.3m long and 0.45m high. The fatigue load and impact excitation were applied on the specimen sequentially. According to the test results, the concrete crack development and global stiffness degradation during the fatigue test were relatively slow due to the favourable performance of SFRC in tension. But on the other hand, the vibration features varied significantly during the fatigue damage development. Generally, it confirmed the feasibility of executing fatigue damage assessment of composite bridge based on vibration method.
Full Text Available This paper aims to evaluate the impact interaction between the abutment and the girder subjected to nonuniform seismic excitation. An impact model based on tests is presented by taking material properties of the backfill of the abutment into consideration. The conditional simulation is performed to investigate the spatial variation of earthquake ground motions. A two-span continuous steel box girder bridge is taken as the example to analyze and assess the pounding interaction between the abutment and the girder. The detailed nonlinear finite element (FE model is established and the steel girder and the reinforced concrete piers are modeled by nonlinear fiber elements. The pounding element of the abutment is simulated by using a trilinear compression gap element. The elastic-perfectly plastic element is used to model the nonlinear rubber bearings. The comparisons of the pounding forces, the shear forces of the nonlinear bearings, the moments of reinforced concrete piers, and the axial pounding stresses of the steel girder are studied. The made observations indicate that the nonuniform excitation for multisupport bridge is imperative in the analysis and evaluation of the pounding effects of the bridges.
Chithra, J.; Nagarajan, Praveen; S, Sajith A.
Box girder bridges are one of the best options for bridges with span more than 25 m. For the study of these bridges, three-dimensional finite element analysis is the best suited method. However, performing three-dimensional analysis for routine design is difficult as well as time consuming. Also, software used for the three-dimensional analysis are very expensive. Hence designers resort to simplified analysis for predicting longitudinal and transverse bending moments. Among the many analytical methods used to find the transverse bending moments, SFA is the simplest and widely used in design offices. Results from simplified frame analysis can be used for the preliminary analysis of the concrete box girder bridges.From the review of literatures, it is found that majority of the work done using SFA is restricted to the analysis of single cell box girder bridges. Not much work has been done on the analysis multi-cell concrete box girder bridges. In this present study, a double cell concrete box girder bridge is chosen. The bridge is modelled using three- dimensional finite element software and the results are then compared with the simplified frame analysis. The study mainly focuses on establishing correction factors for transverse bending moment values obtained from SFA.
Full Text Available In engineer design, basic complex method has not enough global search ability for the nonlinear optimization problem, so it mixed with particle swarm optimization (PSO has been presented in the paper,that is the optimal particle evaluated from fitness function of particle swarm displacement complex vertex in order to realize optimal principle of the largest complex central distance.This method is applied to optimization design problems of box girder of bridge crane with constraint conditions.At first a mathematical model of the girder optimization has been set up,in which box girder cross section area of bridge crane is taken as the objective function, and its four sizes parameters as design variables, girder mechanics performance, manufacturing process, border sizes and so on requirements as constraint conditions. Then complex method mixed with PSO is used to solve optimization design problem of cane box girder from constrained optimization studying approach, and its optimal results have achieved the goal of lightweight design and reducing the crane manufacturing cost . The method is reliable, practical and efficient by the practical engineer calculation and comparative analysis with basic complex method.
Full Text Available The Naval Undersea Warfare Center has funded research to examine a range of finite element approaches used for modeling bolted connections subjected to various loading conditions. Research focused on developing finite element bolt representations that were accurate and computationally efficient. A variety of finite element modeling approaches, from detailed models to simplified ones, were used to represent the behavior of single solid bolts under static and dynamic tension loading. Test cases utilized models of bolted connection test arrangements (static tension and dynamic tension developed for previous research and validated against test data for hollow bore bolts (Behan et al., 2013. Simulation results for solid bolts are validated against experimental data from physical testing of bolts in these load configurations.
Abdel-Mohti, Ahmed; Pekcan, Gokhan
It is critical to ensure the functionality of highway bridges after earthquakes to provide access to important facilities. Since the 1971 San Fernando earthquake, there has been a better understanding of the seismic performance of bridges. Nonetheless, there are no detailed guidelines addressing the performance of skewed highway bridges. Several parameters affect the response of skewed highway bridges under both service and seismic loads which makes their behavior complex. Therefore, there is a need for more research to study the effect of skew angle and other related factors on the performance of highway bridges. This paper examines the seismic performance of a three-span continuous concrete box girder bridge with skew angles from 0 to 60 degrees, analytically. Finite element (FE) and simplified beam-stick (BS) models of the bridge were developed using SAP2000. Different types of analysis were considered on both models such as: nonlinear static pushover, and linear and nonlinear time history analyses. A comparison was conducted between FE and BS, different skew angles, abutment support conditions, and time history and pushover analysis. It is shown that the BS model has the capability to capture the coupling due to skew and the significant modes for moderate skew angles. Boundary conditions and pushover load profile are determined to have a major effect on pushover analysis. Pushover analysis may be used to predict the maximum deformation and hinge formation adequately.
Full Text Available Heat curving is a practical and economical process used by steel fabricators for curving structural steel. In this method, the flange edges of a fabricated straight girder are asymmetrically heated to induce residual curvature on cooling. Available analytical methods for predicting the resulting residual stress, strain and curvature are complex and iterative because of the need to account for material and geometric non-linearity. This paper presents a single-step, non-iterative, numerical procedure for determining the effects of heat-curving on residual stress and strain based on a previously developed simplified analysis. Thermal equilibrium equations for idealized heating profiles are first recast in a general parametric form and then solved numerically for standard heating width and temperature using modern technical computing. The resulting solutions are expressed as polynomial functions to allow the solution space for the residual curvature to be graphically represented. Curvature predictions using this simplified approach are shown to be within 11% of measured values and within 5% of values obtained using more rigorous numerical methods.
Tränkner, Conny; Pfeiffer, Nina; Kirchhoff, Martin; Kopisch-Obuch, Friedrich J; van Dijk, Henk; Schilhabel, Markus; Hasler, Mario; Emrani, Nazgol
Only few genetic loci are sufficient to increase the variation of bolting time in Beta vulgaris dramatically, regarding vernalization requirement, seasonal bolting time and reproduction type. Beta species show a wide variation of bolting time regarding the year of first reproduction, seasonal bolting time and the number of reproduction cycles. To elucidate the genetics of bolting time control, we used three F 3 mapping populations that were produced by crossing a semelparous, annual sugar beet with iteroparous, vernalization-requiring wild beet genotypes. The semelparous plants died after reproduction, whereas iteroparous plants reproduced at least twice. All populations segregated for vernalization requirement, seasonal bolting time and the number of reproduction cycles. We found that vernalization requirement co-segregated with the bolting locus B on chromosome 2 and was inherited independently from semel- or iteroparous reproduction. Furthermore, we found that seasonal bolting time is a highly heritable trait (h 2 > 0.84), which is primarily controlled by two major QTL located on chromosome 4 and 9. Late bolting alleles of both loci act in a partially recessive manner and were identified in both iteroparous pollinators. We observed an additive interaction of both loci for bolting delay. The QTL region on chromosome 4 encompasses the floral promoter gene BvFT2, whereas the QTL on chromosome 9 co-localizes with the BR 1 locus, which controls post-winter bolting resistance. Our findings are applicable for marker-assisted sugar beet breeding regarding early bolting to accelerate generation cycles and late bolting to develop bolting-resistant spring and winter beets. Unexpectedly, one population segregated also for dwarf growth that was found to be controlled by a single locus on chromosome 9.
Full Text Available Numerous experimental and numerical studies on prismatic plate girders subjected to shear can be found in the literature. However, the real structures are frequently designed as non-uniform structural elements. The main objective of the research is the development of a new proposal for the calculation of the ultimate shear resistance of tapered steel plate girders taking into account the specific behaviour of such members. A new mechanical model is presented in the paper and it is used to show the differences between the behaviour of uniform and tapered web panels subjected to shear. EN 1993-1-5 design specifications for the determination of the shear strength for rectangular plates are improved in order to assess the shear strength of tapered elements. Numerical studies carried out on tapered steel plate girders subjected to shear lead to confirm the suitability of the mechanical model and the proposed design expression.
Mohamed A. ElShaer
In this paper, a non-linear finite element analysis has been done to analyze the deflection in the steel section and internal stresses in the concrete slab for continuous composite girders with a single rectangular opening in the steel web. ANSYS computer program (version 15 has been used to analyze the three-dimensional model. The reliability of the model was demonstrated by comparison with experimental results of continuous composite beams without an opening in the steel web carried out by another author. The parametric analysis was executed to investigate the width, height, and position of the opening in one span on the behavior of a composite girder under vertical load. The results indicated that when the width of opening is less than 0.05 of length of a single span and the height is less than 0.15 of the steel web, the deflection and internal stresses increased less than 10% comparing to continuous composite girders without an opening.
Lárusson, Lárus Helgi; Fischer, Gregor
reinforcement serves as a flexible concrete element between the adjacent deck segments. The use of an Engineered Cementitious Composite (ECC) material instead of conventional concrete significantly reduces crack widths under service conditions and prevents deterioration of the link slab in the tension......Deterioration of bridge structures with mechanical expansion joints between simply supported spans can cause repeated maintenance needs and high repair costs. Damage occurs due to accumulation of debris within the expansion joint, corrosion of deck reinforcement, spalling of concrete, leakage...... of water through the expansion joint and subsequent corrosion of girders and girder bearings. Investigations on joint-less superstructures using conventional steel reinforcement in so-called concrete link slabs indicate improved performance and economic feasibility. However, this concept requires...
Li, Xiaodan; Huang, Shuangjun; Xu, Liang; Hui, Li; Zhou, Song
The bolt structural properties of selective laser melted (SLM) samples produced from TC4 powder metal has been investigated. Two different connection molds relative to single lap joint and bilateral lap joint as well as two different state of surface quality were considered. Samples and test procedures were designed in accordance with HB 5143 and HB 5287 standard. The results show that there is a strong influence of connection molds on the dynamic behavior of SLM produced TC4. The mechanical properties of bilateral lap joint are better than those of the single lap joint. Meanwhile the fatigue performance of the bilateral lap joint is much stronger than that of the single lap joint which it is a symmetrical structure of the two-shear test on both sides of the force evenly, while the single lap joint is a single shear sample of the uneven force. There are two kinds of fracture form most of which are broken in the first row of screw and a small part in the middle of the connecting plate.
He, L.; An, X. M.; Zhao, X. B.; Zhao, Z. Y.; Zhao, J.
In this paper, a unified rock bolt model is proposed and incorporated into the two-dimensional discontinuous deformation analysis. In the model, the bolt shank is discretized into a finite number of (modified) Euler-Bernoulli beam elements with the degrees of freedom represented at the end nodes, while the face plate is treated as solid blocks. The rock mass and the bolt shank deform independently, but interact with each other through a few anchored points. The interactions between the rock mass and the face plate are handled via general contact algorithm. Different types of rock bolts (e.g., Expansion Shell, fully grouted rebar, Split Set, cone bolt, Roofex, Garford and D-bolt) can be realized by specifying the corresponding constitutive model for the tangential behavior of the anchored points. Four failure modes, namely tensile failure and shear failure of the bolt shank, debonding along the bolt/rock interface and loss of the face plate, are available in the analysis procedure. The performance of a typical conventional rock bolt (fully grouted rebar) and a typical energy-absorbing rock bolt (D-bolt) under the scenarios of suspending loosened blocks and rock dilation is investigated using the proposed model. The reliability of the proposed model is verified by comparing the simulation results with theoretical predictions and experimental observations. The proposed model could be used to reveal the mechanism of each type of rock bolt in realistic scenarios and to provide a numerical way for presenting the detailed profile about the behavior of bolts, in particular at intermediate loading stages.
He, Minjuan; Tao, Duo; Li, Zheng; Li, Maolin
As a renewable building material with low embodied energy characteristics, wood has gained more and more attention in the green and sustainable building industry. In terms of material resource and physical properties, scrimber composite not only makes full use of fast-growing wood species, but also has better mechanical performance and less inherent variability than natural wood material. In this study, the mechanical behavior of bolted beam-to-column joints built with a kind of scrimber composite was investigated both experimentally and numerically. Two groups of specimens were tested under monotonic and low frequency cyclic loading protocols. The experimental results showed that the bolted joints built with scrimber composite performed well in initial stiffness, ductility, and energy dissipation. A three-dimensional (3D) non-linear finite element model (FEM) for the bolted beam-to-column joints was then developed and validated by experimental results. The validated model was further used to investigate the failure mechanism of the bolted joints through stress analysis. This study can contribute to the application of the proposed scrimber composite in structural engineering, and the developed FEM can serve as a useful tool to evaluate the mechanical behavior of such bolted beam-to-column joints with different configurations in future research.
Full Text Available Pyrotechnic release devices such as explosive bolts are prevalent for many applications due to their merits: high reliability, high power-to-weight ratio, reasonable cost, and more. However, pyroshock generated by an explosive event can cause failures in electric components. Although pyroshock propagations are relatively well understood through many numerical and experimental studies, the prediction of pyroshock generation is still a very difficult problem. This study proposes a numerical method for predicting the pyroshock of a ridge-cut explosive bolt using a commercial hydrocode (ANSYS AUTODYN. A numerical model is established by integrating fluid-structure interaction and complex material models for high explosives and metals, including high explosive detonation, shock wave transmission and propagation, and stress wave propagation. To verify the proposed numerical scheme, pyroshock measurement experiments of the ridge-cut explosive bolts with two types of surrounding structures are performed using laser Doppler vibrometers (LDVs. The numerical analysis results provide accurate prediction in both the time (acceleration and frequency domains (maximax shock response spectra. In maximax shock response spectra, the peaks due to vibration modes of the structures are observed in both the experimental and numerical results. The numerical analysis also helps to identify the pyroshock generation source and the propagation routes.
Li, Guo dong; Li, Nan
High-strength bolts have been widely used in power plants. However, the high-strength bolts which being employed in pumping station, steel structure and pipeline anti-whip structure have been found delayed fracture for many times in a power plant, this will affect the reliability of steel fracture and bring blow risk caused by falling objects. The high-strength bolt with delayed fracture was carried out fracture analysis, metallurgical analysis, chemical analysis, mechanical analysis, as well as bolts installation analysis, it can be comprehensively confirmed that the direct cause of high-strength bolts delayed fracture is the stress corrosion, and the root cause of high-strength bolts delayed fracture should be the improper installation at the initial and the imperfect routine anti-corrosion maintenance.
Nah, Hwan-Seon; Kim, Kang-Seok; Lee, Hyeon-Ju; Kim, Woo-Bum
In case of Korean nuclear power plant, the field design of bolted connection for steel structures has been changed from high strength hexagon bolt to torque shear bolt. The torque control method is mainly used as a clamping method of high strength bolt at construction site. However the torque coefficient affects the design strength in tension on the process of tightening by torque control. This is why it is obscure to assume quantitatively the direct tension induced into bolt. The determinant factor affected on the clamping force is ambient temperature as Korean standard B 2819 indicated. This study was planned to assess the expected clamping force on two kinds of high strength bolts considering temperature ranged from -10degC to 50degC. From test data subjected to temperature parameters, the equation to estimate the clamping force was extracted by regression analysis. (author)
Chen, Shi-Zhi; Wu, Gang; Xing, Tuo
After several years of operation, a box girder bridge would commonly experience excessive deflection, which endangers the bridge’s life span as well as the safety of vehicles travelling on it. In order to avoid potential risks, it is essential to constantly monitor the defection of box girders. However, currently, the direct deflection monitoring methods are limited by the complicated environments beneath the bridges, such as rivers or other traffic lanes, which severely impede the layouts of the sensors. The other indirect deflection monitoring methods mostly do not thoroughly consider the inherent shear lag effect and shear deformation in the box girder, resulting in a rather large error. Under these circumstances, a deflection monitoring method suiting box girders is proposed in this article, based on the conjugate beam method and distributed long-gauge fibre Bragg grating (FBG) sensor. A lab experiment was conducted to verify the reliability and feasibility of this method under practical application. Further, the serviceability under different span-depth ratios and web thicknesses was examined through a finite element model.
Full Text Available The main objective of this paper was to investigate the effect of material uncertainties on dynamic response of segmental box girder bridge subjected to a moving load, in this case a rapid passing trains. Literatures concerned with the design of segmental box girder bridge, the application of finite element analysis to model the segmental box girder bridge, and the minimum requirement for structural conditions of the bridge were described and discussed in detail. A series of finite element analysis was carried out using SAP2000 Nonlinear software. The effect was investigated by varying the Modulus of Elasticity by 5%, 10% and 15%. The results were then compared with the case of assumed uniform property which had already been checked for model accuracy using the Standard prEN 1991-2. The results showed that, for the uniform case, the dynamic responses of the bridge gave the highest response at the resonance speed. When considering the non-uniform material properties (non-uniform case, the effect of material uncertainties appeared to have an effect on both displacement and acceleration responses. Nonetheless, the dynamic factor provided in the design code was sufficient for designing the segmental box girder bridge with either uniform or non-uniform material properties for the train speeds considered in this study.
Optimization of the box-girder of overhead crane with constrained new bat algorithm. Optimisation de poutre caisson de pont roulant avec un nouvel algorithme de chauve souris sous contrainte. Asma Chakri*, Rabia Khelif & Mohamed Benouaret. Industrial Mechanics Laboratory, Department of Mechanical Engineering, ...
The Wolf Creek Bridge is a curved, multi-girder three span steel composite bridge located south of Narrows, Virginia, that was completed in 2006. A finite element model of the bridge revealed that pier flexibility may be important in modeling the bri...
Melcher, J.; Škaloud, Miroslav; Kala, Z.; Karmazínová, M.
Roč. 5, č. 2 (2009), s. 120-126 ISSN 1816-112X. [International conf. on steel and aluminium structures /6./. Oxford, 24.06.2007-27.06.2007] Institutional research plan: CEZ:AV0Z20710524 Keywords : steel structures * fatigue * sensitivity * imperfection * plated girder Subject RIV: JM - Building Engineering
Phased construction is a common practice used by State DOTs during the : replacement of a bridge. This method allows for the traffic flow to be maintained on half : of the bridge while a new deck is constructed on the other half. For steel girder bri...
Therefore, the analytical tool for this study is a MATLAB program developed by the authors for the finite strip analysis of continuous thin-walled box girder bridges. Numerical study on stress distribution was ... The beam theory solution was also used for comparison of results in both cases. The study concluded that under ...
Hong, Dong-Soo; Park, Jae-Hyung; Kim, Jeong-Tae; Na, Won-Bae
Acceleration and impedance signatures extracted from a structure are appealing features for a prompt diagnosis on structural condition since those are relatively simple to measure and utilize. However, the feasibility of using them for damage monitoring is limited when their changes go undisclosed due to uncertain temperature conditions, particularly for large structures. In this study, temperature effect on hybrid damage monitoring of prestress concrete (PSC) girder bridges is presented. In order to achieve the objective, the following approaches are implemented. Firstly, a hybrid monitoring algorithm using acceleration and impedance signatures is proposed. The hybrid monitoring algorithm mainly consists of three sequential phases: 1) the global occurrence of damage is alarmed by monitoring changes in acceleration features, 2) the type of damage is identified as either prestress-loss or flexural stiffness-loss by identifying patterns of impedance features, 3) the location and the extent of damage are estimated from damage index method using natural frequency and mode shape changes. Secondly, changes in acceleration and impedance signatures were investigated under various temperature conditions on a laboratory-scaled PSC girder model. Then the relationship between temperatures and those signatures is analyzed to estimate and a set of empirical correlations that will be utilized for the damage alarming and classification of PSC girder bridges. Finally, the feasibility of the proposed algorithm is evaluated by using a lab-scaled PSC girder bridge for which acceleration and impedance signatures were measured for several damage scenarios under uncertain temperature conditions.
Křístek, V.; Škaloud, Miroslav
Roč. 40, č. 2 (2000), s. 78-80 ISSN 1210-2709. [First International Conference on Advanced Engineering Design . Praha, 31.05.1999-02.06.1999] R&D Projects: GA ČR GA103/97/0074 Keywords : steel bridges * box girder * shear effects * deflections * design Subject RIV: JM - Building Engineering
Keywords: Overhead crane - Box-girder - New bat algorithm - level of comparison - Higher strength steel. Optimisation de poutre caisson de pont roulant avec un nouvel algorithme de chauve souris sous contrainte. Une conception optimale pour un poids minimal de la poutre principale d'un pont roulant peut réduire ...
Full Text Available A reliability assessment method for prestressed concrete (PSC continuous box-girder bridges based on structural health monitoring (SHM strain measurements was proposed. First, due to the fact that measured strain was compositive and the variation periods of its components were different, a series of limit state equations under normal use limit state were given. Then, a linear fitting method was used to determine the relationship between the ambient temperature and the measured strain, which was aimed at extracting the vehicle load effect and the temperature load effect from the measured strain. Finally, according to the equivalent normalization method, the load effects unsatisfying the normal distribution by probability density function fitting were transformed, and the daily failure probabilities of monitored positions were calculated for evaluating the safety state of the girder. The results show that (1 the top plate of the box girder is more sensitive than the bottom plate to the high temperature, (2 the daily and seasonal strain variations induced by uniform temperature reveal an inconsistent tendency to the seasonal variation for mid-span cross sections, and (3 the generalized extreme value distribution is recommended for temperature gradient stress and vehicle induced stress fitting for box-girder bridges.
Jiao, Pengcheng; Borchani, Wassim; Hasni, Hassene; Lajnef, Nizar
This study develops a novel buckling-based mechanism to measure the thermal response of prestressed concrete bridge girders under continuous temperature changes for structural health monitoring. The measuring device consists of a bilaterally constrained beam and a piezoelectric polyvinylidene fluoride transducer that is attached to the beam. Under thermally induced displacement, the slender beam is buckled. The post-buckling events are deployed to convert the low-rate and low-frequency excitations into localized high-rate motions and, therefore, the attached piezoelectric transducer is triggered to generate electrical signals. Attaching the measuring device to concrete bridge girders, the electrical signals are used to detect the thermal response of concrete bridges. Finite element simulations are conducted to obtain the displacement of prestressed concrete girders under thermal loads. Using the thermal-induced displacement as input, experiments are carried out on a 3D printed measuring device to investigate the buckling response and corresponding electrical signals. A theoretical model is developed based on the nonlinear Euler-Bernoulli beam theory and large deformation assumptions to predict the buckling mode transitions of the beam. Based on the presented theoretical model, the geometry properties of the measuring device can be designed such that its buckling response is effectively controlled. Consequently, the thermally induced displacement can be designed as limit states to detect excessive thermal loads on concrete bridge girders. The proposed solution sufficiently measures the thermal response of concrete bridges.
section area of the box-girder as objective function, and restrictions on plates' stress, fatigue, buckling and allowable deflection. The resulted problem is solved with constrained new bat algorithm. Four modifications have been embedded to the standard bat algorithm to increase its performances, and the level of ...
Anne Katherine Kawohl
Full Text Available Prior investigations of the load-bearing capacity of bolts during fire have shown differing behaviour between bolts that have been loaded by shear or by tensile loads. A combination of the two loads has not yet been examined under fire conditions. This paper describes a series of tests on high-strength bolts of property class 10.9 both during and after fire under a combined shear and tensile load.
Full Text Available In the thread root area of the threaded bolts submitted to axial loading occur local stresses, higher that nominal stresses calculated for the bolts. These local stresses can generate failure and can reduce the fatigue life of the parts. The paper is focused on the study of the influence of the thread root radius on the maximum local stresses. A large diameter trapezoidal bolt was subjected to a static analysis (axial loading using finite element simulation.
Full Text Available The basic type of rock mass reinforcement method for both preparatory and operational workings in underground metal ore mines, both in Poland and in different countries across the world, is the expansion shell or adhesive-bonded rock bolt. The article discusses results of static loading test of the expansion shell rock bolts equipped with originally developed deformable component. This component consists of two profiled rock bolt washers, two disk springs, and three guide bars. The disk spring and disk washer material differs in stiffness. The construction materials ensure that at first the springs under loading are partially compressed, and then the rock bolt washer is plastically deformed. The rock bolts tested were installed in blocks simulating a rock mass with rock compressive strength of 80 MPa. The rock bolt was loaded statically until its ultimate loading capacity was exceeded. The study presents the results obtained under laboratory conditions in the test rig allowing testing of the rock bolts at their natural size, as used in underground metal ore mines. The stress-strain/displacement characteristics of the expansion shell rock bolt with the deformable component were determined experimentally. The relationships between the geometric parameters and specific strains or displacements of the bolt rod were described, and the percentage contribution of those values in total displacements, resulting from the deformation of rock bolt support components (washer, thread and the expansion shell head displacements, were estimated. The stiffness of the yielded and stiff bolts was empirically determined, including stiffness parameters of every individual part (deformable component, steel rod. There were two phases of displacement observed during the static tension of the rock bolt which differed in their intensity.
Balagopal, R.; Prasad Rao, N.; Rokade, R. P.; Umesha, P. K.
Due to increase in demand for power supply and increase in bandwidth for communication industry, the existing transmission line (TL) and communication towers needs to be strengthened. The strengthening of existing tower is economical rather than installation of new towers due to constraints in acquisition of land. The size of conductors have to be increased or additional number of antenna needs to be installed in existing TL/communication tower respectively. The compression and tension capacity of members in the existing towers have to be increased to sustain the additional loads due to wind and self-weight of these components. The tension capacity enhancement of existing angle sections in live line condition without power shut-down is a challenging task. In the present study, the use of Glass Fiber Reinforced Plastic (GFRP) plate/angle sections is explored to strengthen existing bolted connections in TL/communication towers. Experimental investigation conducted at component level on strengthening of existing two types of single cover steel butt joint, one made of steel plate and another joint made of steel angle sections respectively. First series of experiment conducted on strengthening the connection using GFRP plate/cleat angle sections. The second series of strengthening experiment is conducted using steel plate/angle sections to replace GFRP sections. The load sharing behaviour of strengthened GFRP and steel section is compared and suitable recommendations are given.
Full Text Available This paper presents experimental results and finite element analysis of the cold-formed steel bolted connection under shear loading. Experiments are conducted to study the ultimate behaviors, such as ultimate strength and failure mode of connections. The samples were fabricated into three different groups, single bolted, double bolted and quadruple bolted connection. Material properties were determined by tensile coupon testing. Bearing failure modes were detected in the bolted connection tests. The ultimate capacities were compared with the nominal strengths calculated using the AISI (2012. The comparisons show that the nominal strength parameters predicted by this specification is conservative. The finite element analysis shell elements were used to model the cold-formed steel plate while solid elements were used to model the bolted fastenings for the purpose of studying the structural behavior of bolted connections. Material nonlinearities, contact problem and geometry nonlinearities analysis are carried out in order to predict ultimate strength and failure mode of connections. The results show that the proposed model accurately represents the failure mode and ultimate strength of bolted connection, as determined from experimental investigation. The new factor for type of bearing connection has a good agreement with the tested bearing strength of bolt connection.
Leonard, Keith J. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Sokolov, Mikhail A. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Gussev, Maxim N. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
In support of extended service and current operations of the US nuclear reactor plants, the Oak Ridge National Laboratory (ORNL), through the Department of Energy (DOE), Light Water Reactor Sustainability (LWRS) Program, is coordinating with Ginna Nuclear Power Plant, The Westinghouse Electric Company, LLC, and ATI Consulting, the selective procurement of baffle bolts that were withdrawn from service in 2011 and currently stored on site at Ginna. The goal of this program is to perform detailed microstructural and mechanical property characterization of baffle former bolts following in-service exposures. This report outlines the selection criteria of the bolts and the techniques to be used in this study. The bolts available are the original alloy 347 steel fasteners used in holding the baffle plates to the baffle former structures within the lower portion of the pressurized water reactor vessel. Of the eleven possible bolts made available for this work, none were identified to have specific damage. The bolts, however, did show varying levels of breakaway torque required in their removal. The bolts available for this study varied in peak fluence (highest dose within the head of the bolt) between 9.9 and 27.8x1021 n/cm2 (E>1MeV). As no evidence for crack initiation was determined for the available bolts from preliminary visual examination, two bolts with the higher fluence values were selected for further post-irradiation examination. The two bolts showed different breakaway torque levels necessary in their removal. The information from these bolts will be integral to the LWRS program initiatives in evaluating end of life microstructure and properties. Furthermore, valuable data will be obtained that can be incorporated into model predictions of long-term irradiation behavior and compared to results obtained in high flux experimental reactor conditions. The two bolts selected for the ORNL study will be shipped to Westinghouse with bolts of
Full Text Available The main purpose of rock support and reinforcement in underground mining is to maintain excavations safe and open for their intended lifespan. The basic type of rock mass reinforcement method both in ore and hard coal mining is rock bolt support. Very often, existing bolt support systems are not always capable of providing a reliable controlled performance. Therefore, in recent years energy-absorbing bolts which are exposed to dynamic loading, for example from rock burst caused by high rock stresses, earthquakes, or blasting have appeared. In this article particular attention was paid to short and long expansion bolts. Quasi-static tests of expansion bolts were carried out at the laboratory test facility in simulated mining conditions, especially for the KGHM Polska Miedź S.A. mines. In the underground mines of the Legnica-Głogów Copper District (LGOM the main way to protect the room excavation is rock bolt support with a length from 1.2 m to 2.6 m. Rock bolt support longer than 2.6 m is considered as additional support of excavations and is increasingly being used to reinforce the roofs. The comparisons of energy-absorbing short and long expansion bolts with a length of 1.8m, 3.6m and 5.2m were presented. In addition, for elastic and plastic range of each bolts were determined.
The main purpose of rock support and reinforcement in underground mining is to maintain excavations safe and open for their intended lifespan. The basic type of rock mass reinforcement method both in ore and hard coal mining is rock bolt support. Very often, existing bolt support systems are not always capable of providing a reliable controlled performance. Therefore, in recent years energy-absorbing bolts which are exposed to dynamic loading, for example from rock burst caused by high rock stresses, earthquakes, or blasting have appeared. In this article particular attention was paid to short and long expansion bolts. Quasi-static tests of expansion bolts were carried out at the laboratory test facility in simulated mining conditions, especially for the KGHM Polska Miedź S.A. mines. In the underground mines of the Legnica-Głogów Copper District (LGOM) the main way to protect the room excavation is rock bolt support with a length from 1.2 m to 2.6 m. Rock bolt support longer than 2.6 m is considered as additional support of excavations and is increasingly being used to reinforce the roofs. The comparisons of energy-absorbing short and long expansion bolts with a length of 1.8m, 3.6m and 5.2m were presented. In addition, for elastic and plastic range of each bolts were determined.
Zhang, Y.; Zhang, S.; Hou,C.; Wang, P.; Zhang, M.; Yuan, Q.; Pang, J.; Li, H. [China University of Mining and Technology, Xuzhou (China). Dept. of Mining Engineering
On the basis of numerical simulation, the influence of crustal stress on roof-bolted gob-side roadway is discussed. The discussion includes the perimeter convergence and deep displacement of roadway, the arrangement of rock bolt for gob-side roadway, and the width of support pillar. The research proves the feasibility of supporting gob-side roadway by rock bolt from the angle of crustal stress. The results can provide a reliable foundation for designing the scientific and reasonable parameters of bolt supporting. 2 refs., 6 figs.
Panait, C.; Fargeas, E.; Miloudi, S.; Moulart, P.; Tommy-Martin, M.; Monteil, N.; Pokor, C.
This paper presents the microstructural investigations conducted on a cracked baffle to former bolt extracted from an upper former level of the internal structures of a French Pressurized Water Reactor (PWR). Extensive microstructural investigations using Light Microscopy, Scanning Electron Microscopy and Transmission Electron Microscopy (TEM) have been conducted to understand the degradation mechanisms of this bolt. TEM investigations have revealed neutron irradiation damage in the microstructure of the bolt such as Frank loops and cavities and/or bubbles. The number of features per unit volume as a function of diameter was determined in the head and in the shank of the bolt. The obtained results are relatively similar to those obtained for other damaged bolts extracted from PWR-type reactors and irradiated in similar conditions (dose and temperature). The irradiation damage has induced an evolution of the mechanical properties (hardening of the material), as revealed by the hardness measurements along the bolt, with a higher average value in the head (400 HV), compared to the shank (15 mm under the head), about 340 HV. The metallurgical investigations have confirmed that this bolt was damaged by Irradiation Assisted Stress Corrosion Cracking (IASCC)
The research presented herein describes the field verification for the effectiveness of continuity diaphragms for : skewed continuous precast, prestressed, concrete girder bridges. The objectives of this research are (1) to perform : field load testi...
The objective of this study was to develop an objective, quantitative method for evaluating damage to bridge girders by using artificial neural networks (ANNs). This evaluation method, which is a supplement to visual inspection, requires only the res...
This research investigated the durability of carbon fiber-reinforced polymer composites (CFRP) used for shear strengthening reinforced : concrete deck girders. Large beams were used to avoid accounting for size effects in the data analysis. The effor...
During the interstate expansion of the 1950s, many conventionally reinforced concrete deck girder bridges were built throughout the country. These aging bridges commonly exhibit diagonal cracking and rate inadequately for shear, thus they are candida...
During the interstate expansion of the 1950s, many conventionally reinforced concrete deck girder bridges were built throughout the country. These aging bridges commonly exhibit diagonal cracking and rate inadequately for shear, thus they are candida...
During the interstate expansion of the 1950s, many conventionally reinforced concrete deck girder bridges were built throughout the country. These aging bridges commonly exhibit diagonal cracking and rate inadequately for shear, thus they are candida...
"This research investigated the durability of carbon fiber-reinforced polymer composites (CFRP) used for shear strengthening reinforced concrete deck girders. Large beams were used to avoid accounting for size effects in the data analysis. The effort...
Project -- Work Approach: The first phase will examine the critical problem of controlling cracking in the 82W : girders. This complex problem is controlled by effects of concentrated stresses, force : transfer from pre-tensioning strand, inelastic b...
White, Donald W.; Ramirez, J. A.; Barth, Karl E.
This report summarizes the development and trial application of simplified moment-rotation relationships for inelastic design of continuous-span beam and girder bridges. The research described within involves the execution of a reasonably comprehensive set of finite element parametric studies to fill in knowledge gaps in the available experimental data pertaining to the hogging moment-plastic rotation behavior of steel and composite steel-concrete bridge girders. Based on these studies, relat...
Huo, Linsheng; Wang, Bo; Chen, Dongdong; Song, Gangbing
Rock bolts ensure structural stability for tunnels and many other underground structures. The pre-load on a rock bolt plays an important role in the structural reinforcement and it is vital to monitor the pre-load status of rock bolts. In this paper, a rock bolt pre-load monitoring method based on the piezoceramic enabled time reversal method is proposed. A lead zirconate titanate (PZT) patch transducer, which works as an actuator to generate stress waves, is bonded onto the anchor plate of the rock bolt. A smart washer, which is fabricated by sandwiching a PZT patch between two metal rings, is installed between the hex nut and the anchor plate along the rock bolt. The smart washer functions as a sensor to detect the stress wave. With the increase of the pre-load values on the rock bolt, the effective contact surface area between the smart washer and the anchor plate, benefiting the stress wave propagation crossing the contact surface. With the help of time reversal technique, experimental results reveal that the magnitude of focused signal clearly increases with the increase of the pre-load on a rock bolt before the saturation which happens beyond a relatively high value of the pre-load. The proposed method provides an innovative and real time means to monitor the pre-load level of a rock bolt. By employing this method, the pre-load degradation process on a rock bolt can be clearly monitored. Please note that, currently, the proposed method applies to only new rock bolts, on which it is possible to install the PZT smart washer.
Full Text Available Rock bolts ensure structural stability for tunnels and many other underground structures. The pre-load on a rock bolt plays an important role in the structural reinforcement and it is vital to monitor the pre-load status of rock bolts. In this paper, a rock bolt pre-load monitoring method based on the piezoceramic enabled time reversal method is proposed. A lead zirconate titanate (PZT patch transducer, which works as an actuator to generate stress waves, is bonded onto the anchor plate of the rock bolt. A smart washer, which is fabricated by sandwiching a PZT patch between two metal rings, is installed between the hex nut and the anchor plate along the rock bolt. The smart washer functions as a sensor to detect the stress wave. With the increase of the pre-load values on the rock bolt, the effective contact surface area between the smart washer and the anchor plate, benefiting the stress wave propagation crossing the contact surface. With the help of time reversal technique, experimental results reveal that the magnitude of focused signal clearly increases with the increase of the pre-load on a rock bolt before the saturation which happens beyond a relatively high value of the pre-load. The proposed method provides an innovative and real time means to monitor the pre-load level of a rock bolt. By employing this method, the pre-load degradation process on a rock bolt can be clearly monitored. Please note that, currently, the proposed method applies to only new rock bolts, on which it is possible to install the PZT smart washer.
Currently employed high-strength steam generator support bolting material (designed prior to ASME Section III Part NF or Component Supports), 38.1 mm in diameter, in combination with high preloads are susceptible to stress corrosion cracking because of the relatively low stress corrosion resistance (K/sub ISCC/) properties. These bolts are part of the pressurized water reactor steam generator supports at the integral support pads (three per steam generator, with each pad housing six, eight, or ten bolts depending on the design). The US Nuclear Regulatory Commission concerns for high-strength bolting were identified in NUREG-0577, ''Potential for Low Fracture Toughness and Laminar Tearing in PWR Steam Generator and Reactor Coolant Pump Supports,'' which was issued for comment on unresolved safety issue A-12. Subsequently, the bolting issues were addressed in generic issue B29. One of the issues deals specifically with high-strength bolting materials, which are vulnerable to stress corrosion cracking. A Westinghouse Owners Group funded program was established to develop in situ ultrasonic examination techniques to determine steam generator support bolting integrity at the head-to-shank and first-thread locations. This program was established in order to determine bolting integrity in place. Ultrasonic techniques were developed for both socket-head and flat-head bolt configurations. As a result of this program, in situ ultrasonic examination techniques were developed for examination of PWR steam generator support bolts. By employing these techniques utilities will be able to ensure the integrity of this in-place bolting without incurring the costs previously experienced during removal for surface examinations
Frank, M; Philipp, K P; Franke, E; Frank, N; Bockholdt, B; Grossjohann, R; Ekkernkamp, A
Vole captive bolt devices are powder actuated spring guns that are used as a pest control mean. After having triggered the explosion of the blank cartridge by touching a metal ring around the muzzle, the vole is killed by the massive propulsion of the gas jet. Improper use and recklessness while handling these devices may cause severe injuries with the hand of the operator at particular risk. Currently, there are no experimental investigations on the ballistic background of these devices. An experimental test set-up was designed for measurement of the firing pressure and the dynamic force of the gas jet of a vole captive bolt device. Therefore, a vole captive bolt device was prepared with a pressure take-off channel and a piezoelectric transducer for measurement of the firing pressure. For measurement of the dynamic impact force of the gas jet an annular quartz force sensor was installed on a test bench. Each three simultaneous measurements of the cartridges' firing pressure and the dynamic force of the blast wave were taken at various distances between muzzle and load washer. The maximum gas pressure in the explosion chamber was up to 1100 bar. The shot development over time showed a typical gas pressure curve. Flow velocity of the gas jet was up to 2000 m/s. The maximum impact force of the gas jet at the target showed a strong inverse ratio to the muzzle's distance and was up to 11,500 N for the contact shot distance. Energy density of the gas jet for the close contact shot was far beyond the energy density required for skin penetration. The unique design features (short tube between cartridge mouth and muzzle and narrow diameter of the muzzle) of these gadgets are responsible for the high firing pressure, velocity and force of the gas jet. These findings explain the trauma mechanics of the extensive tissue damage observed in accidental shots of these devices.
Matsubara, T.; Tsutsui, T.; Kamei, Y.; Kitsu, M.
Baffle structure in PWRs Reactor is quite important assembly for the core safety, and Baffle Former Bolts (BFBs) are fastener members for maintaining Baffle structure. It has been reported worldwide that some of BFBs were cracked due to IASCC (Irradiation Assisted Stress Corrosion Cracking) because BFBs are located at core region under severe environments, high neutron flux, high temperature and high stress. According to the material studies of IASCC on austenitic stainless steel, a crack initiation of IASCC is strongly related with the stress and the neutron fluence. For this reason, it is very important for IASCC failure prediction to simulate the stress of BFBs. However, the stress of BFBs are considered to be influenced by several factors and to be changed complexly as operational time increases, by irradiation creep of Bolt itself, swelling of Baffle structure, and so on. Therefore, it is difficult to estimate the stress histories of BFBs (Bolt stress as a function of operational time) precisely. Then, the author has developed the calculation method of the stress histories of BFBs considering irradiation effects (swelling and irradiation creep). In this method, the stress histories of BFBs are calculated by combining two kinds of FE models, Global model (modeled whole Baffle structure which consists of Baffle plates, Former plates and Core Barrel) and Local model (modeled around BFB finely). The whole Baffle structure deformation changes as a function of heat, swelling and irradiated creep are calculated by Global model, and the stress histories of BFBs are calculated by Local model using the outputs (deformations on driving nodes) of Global model. In the FE analysis of Local model, the stress of BFBs are calculated considering irradiation effects and elastic-plastic characteristics depending on neutron fluence, so this method enables to calculate precisely the stress of extreme small area of BFBs surface. This paper shows the outline of the calculation method
Full Text Available Bolting in lettuce is promoted by high temperature and bolting resistance is of great economic importance for lettuce production. But how bolting is regulated at the molecular level remains elusive. Here, a bolting resistant line S24 and a bolting sensitive line S39 were selected for morphological, physiological, transcriptomic and proteomic comparisons. A total of 12204 genes were differentially expressed in S39 vs S24. Line S39 was featured with larger leaves, higher levels of chlorophyll, soluble sugar, anthocyanin and auxin, consistent with its up-regulation of genes implicated in photosynthesis, oxidation-reduction and auxin actions. Proteomic analysis identified 30 differentially accumulated proteins in lines S39 and S24 upon heat treatment, and 19 out of the 30 genes showed differential expression in the RNA-Seq data. Exogenous gibberellins (GA treatment promoted bolting in both S39 and S24, while 12 flowering promoting MADS-box genes were specifically induced in line S39, suggesting that although GA regulates bolting in lettuce, it may be the MADS-box genes, not GA, that plays a major role in differing the bolting resistance between these two lettuce lines.
Han, Yingyan; Chen, Zijing; Lv, Shanshan; Ning, Kang; Ji, Xueliang; Liu, Xueying; Wang, Qian; Liu, Renyi; Fan, Shuangxi; Zhang, Xiaolan
Bolting in lettuce is promoted by high temperature and bolting resistance is of great economic importance for lettuce production. But how bolting is regulated at the molecular level remains elusive. Here, a bolting resistant line S24 and a bolting sensitive line S39 were selected for morphological, physiological, transcriptomic and proteomic comparisons. A total of 12204 genes were differentially expressed in S39 vs. S24. Line S39 was featured with larger leaves, higher levels of chlorophyll, soluble sugar, anthocyanin and auxin, consistent with its up-regulation of genes implicated in photosynthesis, oxidation-reduction and auxin actions. Proteomic analysis identified 30 differentially accumulated proteins in lines S39 and S24 upon heat treatment, and 19 out of the 30 genes showed differential expression in the RNA-Seq data. Exogenous gibberellins (GA) treatment promoted bolting in both S39 and S24, while 12 flowering promoting MADS-box genes were specifically induced in line S39, suggesting that although GA regulates bolting in lettuce, it may be the MADS-box genes, not GA, that plays a major role in differing the bolting resistance between these two lettuce lines.
Syd S. Peng
Roof bolting is the most popular method for underground openings in the mining industry, especially in the bedded deposits such as coal, potash, salt etc. In fact, all U.S. underground coal mine entries are roof-bolted as required by law. However, roof falls still occur frequently in the roof bolted entries. The two possible reasons are: the lack of knowledge of and technology to detect the roof geological conditions in advance of mining, and lack of roof bolting design criteria for modern roof bolting systems. This research is to develop a method for predicting the roof geology and stability condition in real time during roof bolting operation. Based on such information, roof bolting design criteria for modern roof bolting systems will be developed for implementation in real time. In this quarter, the field, theoretical and programming works have been performed toward achieving the research goals set in the proposal. The selected site and the field testing plan enabled us to test all three aspects of roof geological features. The development of the data interpretation methodologies and the geology mapping computer program have also been preceding well.
Hyres, J.; Xu, H.; Kalchik, K.; Thompson, G.
This paper summarizes the results of the laboratory evaluation performed by Babcock and Wilcox on Alloy X-750 clevis bolts removed from the Lower Radial Support System (LRSS) at D.C. Cook Unit 1. A total of 29 clevis bolts - 16 broken and 13 intact - were provided for laboratory analysis and testing to document the extent of degradation, evaluate the integrity of the intact bolts, and identify the bolt degradation/failure mechanism(s). The laboratory work scope included visual and stereo-visual examinations of all bolts. Based on the results of these examinations, four bolts - two broken and two intact - were selected for more detailed analysis/testing, including Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS), optical metallography, microhardness, chemical analysis by Inductively Coupled Plasma-Mass Spectroscopy (ICP-MS), Rockwell hardness testing, and tensile testing. The laboratory data indicated the bolts failed by intergranular stress corrosion cracking (IGSCC). There was no evidence that the bolts failed due to fatigue cracking or mechanical overload. (authors)
The article deals with the activation of bolting elements with a thread on them or equipped with threaded bushing through drilling and installation device. The article also enumerates the most frequently used bolting elements of this type and applied equipment with technical parameters in the coal mines of the ...
Watson, James; Nielsen, Jens Henrik; Overend, Mauro
The use of bolted connections in glass installations is common place in contemporary architecture. However, it is difficult to predict the load bearing capacity of these connections accurately due to the several factors that influence the strength of glass in the region of the bolt hole, namely: ...... connections that are useful for real-world applications. © 2013 Elsevier Ltd....
Full Text Available This study involved applying a design code change on a modular bridge design. The top flange of a modular T-girder bridge was examined by the Korean Highway Bridge Design Code Limit State Design (2015 and was compared with the Korean Highway Bridge Design Code (2010 in terms of the stability under the bending moment. In addition, the cross-sectional height and reinforcement amount were re-designed to obtain a safety factor similar to the original code. The reinforcement arrangement and development of the transverse joints were examined in the section considered. The result indicated that the application of the Korean Highway Bridge Design Code Limit State Design (2015 increased the bending moment safety factor and decreased the width of the transverse joints. The results of the re-design with respect to a safety factor similar to that in the Korean Highway Bridge Design Code (2010 indicated that it was possible to reduce the cross-sectional height and reinforcement amount. Furthermore, based on the obtained section, the results revealed that the width of the transverse joints could be reduced by changing the arrangement of lap splices from the straight bar to the loop.
Shi, Z. M.; Liu, L.; Peng, M.; Liu, C. C.; Tao, F. J.; Liu, C. S.
Full-length bonded rock bolts are commonly used in mining, tunneling and slope engineering because of their simple design and resistance to corrosion. However, the length of a rock bolt and grouting quality do not often meet the required design standards in practice because of the concealment and complexity of bolt construction. Non-destructive testing is preferred when testing a rock bolt's quality because of the convenience, low cost and wide detection range. In this paper, a signal analysis method for the non-destructive sound wave testing of full-length bonded rock bolts is presented, which is based on the Hilbert-Huang transform (HHT). First, we introduce the HHT analysis method to calculate the bolt length and identify defect locations based on sound wave reflection test signals, which includes decomposing the test signal via empirical mode decomposition (EMD), selecting the intrinsic mode functions (IMF) using the Pearson Correlation Index (PCI) and calculating the instantaneous phase and frequency via the Hilbert transform (HT). Second, six model tests are conducted using different grouting defects and bolt protruding lengths to verify the effectiveness of the HHT analysis method. Lastly, the influence of the bolt protruding length on the test signal, identification of multiple reflections from defects, bolt end and protruding end, and mode mixing from EMD are discussed. The HHT analysis method can identify the bolt length and grouting defect locations from signals that contain noise at multiple reflected interfaces. The reflection from the long protruding end creates an irregular test signal with many frequency peaks on the spectrum. The reflections from defects barely change the original signal because they are low energy, which cannot be adequately resolved using existing methods. The HHT analysis method can identify reflections from the long protruding end of the bolt and multiple reflections from grouting defects based on mutations in the instantaneous
Oh, W.D.; Lee, J.H.; Choi, S.W.; Park, M.H.
The stud bolt is one of the most critical parts for the safety of reactor vessels in nuclear power plants. However, in the practical application of ultrasonic technique for crack detection in stud bolt, the classification of crack signal from the signals reflected from threads in stud bolt is very difficult. In this study, shadow effect technique combined with new signal processing method has been investigated to enhance the detectability of small crack initiated from root of thread in stud bolt. The key idea of new signal processing concept is based on the fact that the shape of waveforms from the threads is uniform since the shape of the threads in a bolt is same. If some cracks exist in the thread, the flaw signals are different from the reference signals. It has shown that the small flaws can be effectively detected by novel ultrasonic technique combined with this new signal processing concept. (orig.)
Kim, Kang-Seok; Nah, Hwan-Seon; Lee, Hyeon-Ju; Lee, Kang-Min
It has been reported that the length parameter of high strength bolts results in the variance in tension loads. The required turn for each length is specified in AISC RCSC specification. This study was focused on evaluating any influence on the clamping torque subjected to length parameter of high strength bolts. The two kinds of high strength bolts of specimen are as follows; High Strength Hexagon bolt defined on ASTM A490 and Torque Shear Bolt on KS B 2819. The length parameter ranged from 60mm(3d) to 140mm(7d). The torque, turn of nut and the clamping force were analyzed to review whether length parameter can be affected on the required tension load. To test whether the length parameter has an impact on the torque and turn of nut for the required strength and clamping force, statistical analysis is carried out. (author)
Noma, Atsushi; He, Jianmei
Threaded fasteners using bolts is widely applied in industrial field as well as various fields. However, threaded fasteners using bolts have loosing problems and cause many accidents. In this study, the purpose is to obtain self-loosing preventable threaded fasteners by applying spring characteristic effects on bolt structures. Helical-cutting applied bolt structures is introduced through three dimensional (3D) CAD modeling tools. Analytical approaches for evaluations on the spring characteristic effects helical-cutting applied bolt structures and self-loosing preventable performance of threaded fasteners were performed using finite element method and results are reported. Comparing slackness test results with analytical results and more details on evaluating mechanical properties will be executed in future study.
Biruk B. Seyoum
Full Text Available Thermoelectric generators (TEGs are now capable of powering the abundant low power electronics from very small (just a few degrees Celsius temperature gradients. This factor along with the continuously lowering cost and size of TEGs, has contributed to the growing number of miniaturized battery-free sensor modules powered by TEGs. In this article, we present the design of an ambient-powered wireless bolt for high-end electro-mechanical systems. The bolt is equipped with a temperature sensor and a low power RF chip powered from a TEG. A DC-DC converter interfacing the TEG with the RF chip is used to step-up the low TEG voltage. The work includes the characterizations of different TEGs and DC-DC converters to determine the optimal design based on the amount of power that can be generated from a TEG under different loads and at temperature gradients typical of industrial environments. A prototype system was implemented and the power consumption of this system under different conditions was also measured. Results demonstrate that the power generated by the TEG at very low temperature gradients is sufficient to guarantee continuous wireless monitoring of the critical fasteners in critical systems such as avionics, motorsport and aerospace.
Flanges in piping systems and also pressure vessel flanges on tall columns are often subjected to longitudinal bending moments of considerable magnitude, be it from thermal expansion stresses in piping systems or from wind or seismic loadings on tall vertical pressure vessels. Except for the ASME Code, Section III, Subsections NB, NC, and ND, other pressure vessel and piping codes do not contain design ASME Nuclear Power Plant Code (Section III), an empirical formula is given, expressing a longitudinal bending moment in bolted flanged connections in terms of an equivalent internal pressure to be added to the design pressure of the flange. In this paper, an attempt is made to analyse the stresses on flanges and bolting due to external bending moments and to compare flange thicknesses thus obtained with thicknesses required using the equivalent design pressure specified in Subsections NB, NC, and ND. A design method is proposed, based on analysis and experimental work, which may be suitable for flange bending moment analysis when the rules of the Nuclear Power Plant Code are not mandatory. (orig.)
Seyoum, Biruk B; Rossi, Maurizio; Brunelli, Davide
Thermoelectric generators (TEGs) are now capable of powering the abundant low power electronics from very small (just a few degrees Celsius) temperature gradients. This factor along with the continuously lowering cost and size of TEGs, has contributed to the growing number of miniaturized battery-free sensor modules powered by TEGs. In this article, we present the design of an ambient-powered wireless bolt for high-end electro-mechanical systems. The bolt is equipped with a temperature sensor and a low power RF chip powered from a TEG. A DC-DC converter interfacing the TEG with the RF chip is used to step-up the low TEG voltage. The work includes the characterizations of different TEGs and DC-DC converters to determine the optimal design based on the amount of power that can be generated from a TEG under different loads and at temperature gradients typical of industrial environments. A prototype system was implemented and the power consumption of this system under different conditions was also measured. Results demonstrate that the power generated by the TEG at very low temperature gradients is sufficient to guarantee continuous wireless monitoring of the critical fasteners in critical systems such as avionics, motorsport and aerospace.
Wieser, G.; Qiao, L.; Eberle, A.; Voelzke, H.
Analysis of complex bolted cask lid structures under mechanical or thermal accident conditions is important for the evaluation of cask integrity and leak tightness in package design assessment according to the transport regulations or in aircraft crash scenarios. In this context BAM is developing methods based on finite elements (FE) to calculate the effects of mechanical impacts onto the bolted lid structures as well as effects caused by severe fire scenarios. In the case of fire it might not be enough to perform only a thermal heat transfer analysis. A complex cask design together with a severe hypothetical time-temperature curve representing an accident fire scenario will create a strong transient heating up of the cask body and its lid system. This causes relative displacements between the seals and their counterparts that can be analysed by a so-called thermomechanical calculation. Although it is currently not possible to directly correlate leakage rates with results from deformation analyses, an appropriate finite element model of the considered type of metallic lid seal has been developed. For the present it is possible to estimate the behaviour of the seal based on the calculated relative displacements at its seating and the behaviour of the lid bolts under the impact load or the temperature field, respectively. Except for the lid bolts, the geometry of the cask and the mechanical loading is axisymmetric which simplifies the analysis considerably, and a two-dimensional finite-element model with substitute lid bolts may be used. The substitute bolts are modelled as one-dimensional truss or beam elements. An advanced two-dimensional bolt submodel represents the bolts with plane stress continuum elements. This paper discusses the influence of different bolt modellings on the relative displacements at the seating of the seals. The influence of bolt modelling, thermal properties and the detailed geometry of the two-dimensional finite-element models on the
Wieser, G.; Qiao Linan; Eberle, A.; Voelzke, H.
The analysis of complex bolted cask lid structures under mechanical or thermal accident conditions is important for the evaluation of cask integrity and leak-tightness in package design assessment according to the Transport Regulations or in aircraft crash scenarios. In this context BAM is developing methods based on Finite Elements to calculate the effects of mechanical impacts onto the bolted lid structures as well as effects caused by severe fire scenarios. I n case of fire it might be not enough to perform only a thermal heat transfer analysis. The complex cask design in connection with a severe hypothetical time-temperature-curve representing an accident fire scenario will create a strong transient heating up of the cask body and its lid system. This causes relative displacements between the seals and its counterparts that can be analyzed by a so-called thermo-mechanical calculation. Although it is currently not possible to correlate leakage rates with results from deformation analyses directly an appropriate Finite Element model of the considered type of metallic lid seal has been developed. For the present it is possible to estimate the behaviour of the seal based on the calculated relative displacements at its seating and the behaviour of the lid bolts under the impact load or the temperature field respectively. Except of the lid bolts the geometry of the cask and the mechanical loading is axial-symmetric which simplifies the analysis considerably and a two-dimensional Finite Element model with substitute lid bolts may be used. The substitute bolts are modelled as one-dimensional truss or beam elements. An advanced two-dimensional bolt submodel represents the bolts with plane stress continuum elements. This paper discusses the influence of different bolt modelling on the relative displacements at the seating of the seals. Besides this, the influence of bolt modelling, thermal properties and detail in geometry of the two-dimensional Finite Element models on
Full Text Available In bridge engineering, girders with corrugated steel webs have shown good mechanical properties. With the promotion of composite bridge with corrugated steel webs, in particular steel-concrete composite girder bridge with corrugated steel webs, it is necessary to study the shear performance and buckling of the corrugated webs. In this research, by conducting experiment incorporated with finite element analysis, the stability of H shape beam welded with corrugated webs was tested and three failure modes were observed. Structural data including load-deflection, load-strain, and shear capacity of tested beam specimens were collected and compared with FEM analytical results by ANSYS software. The effects of web thickness, corrugation, and stiffening on shear capacity of corrugated webs were further discussed.
Nguyen, Khac Duy; Lee, So Young; Kim, Jeong Tae [Pukyong National University, Busan (Korea, Republic of)
Ensuring the designed prestress force is very important for the safety of prestressed concrete bridge. The loss of prestress force in tendon could significantly reduce load carrying capacity of the structure. In this study, an automated prestress-loss monitoring system for prestressed concrete girder using PZT-interface and wireless impedance sensor node is presented. The following approaches are carried out to achieve the objective. Firstly, wireless impedance sensor nodes are designed for automated impedance-based monitoring technique. The sensor node is mounted on the high-performance Imote2 sensor platform to fulfill high operating speed, low power requirement and large storage memory. Secondly, a smart PZT-interface designed for monitoring prestress force is described. A linear regression model is established to predict prestress-loss. Finally, a system of the PZT-interface interacted with the wireless sensor node is evaluated from a lab-scale tendon-anchorage connection of a prestressed concrete girder.
Full Text Available The structural optimization method of steel cantilever used in concrete box girder bridge widening is illustrated in this paper. The structural optimization method of steel cantilever incorporates the conceptual layout design of steel cantilever beam based on the topological theory and the determination of the optimal location of the transverse external prestressed tendons which connect the steel cantilever and the box girder. The optimal design theory and the analysis process are illustrated. The mechanical model for the prestressed steel cantilever is built and the analytical expression of the optimal position of the transverse external tendon is deduced. At last the effectiveness of this method is demonstrated by the design of steel cantilevers which are used to widen an existing bridge.
Nguyen, Khac Duy; Lee, So Young; Kim, Jeong Tae
Ensuring the designed prestress force is very important for the safety of prestressed concrete bridge. The loss of prestress force in tendon could significantly reduce load carrying capacity of the structure. In this study, an automated prestress-loss monitoring system for prestressed concrete girder using PZT-interface and wireless impedance sensor node is presented. The following approaches are carried out to achieve the objective. Firstly, wireless impedance sensor nodes are designed for automated impedance-based monitoring technique. The sensor node is mounted on the high-performance Imote2 sensor platform to fulfill high operating speed, low power requirement and large storage memory. Secondly, a smart PZT-interface designed for monitoring prestress force is described. A linear regression model is established to predict prestress-loss. Finally, a system of the PZT-interface interacted with the wireless sensor node is evaluated from a lab-scale tendon-anchorage connection of a prestressed concrete girder
Cook, Wesley J
The Utah Department of Transportation (UDOT) has implemented the use of precast concrete panels for bridge deck construction. A bridge utilizing these panels as a reconstruction method was decommissioned three years after the new deck installation, due to unrelated matters. Two sections of this bridge were salvaged and sent to Utah State University (USU) for destructive testing. Each bridge section consisted of two built-up steel plate girders intact with the precast concrete deck panels...
Ahmed M. AbdElrahman Massoud*, Manar M. M. Hussein, Walid A.L. Attia
Composite steel/concrete girder is one of the main structural systems used in bridges and buildings. Steel element mainly located in tension zone and a concrete element located in compression zone. Full integration by the shear connectors used to simulate as one section without any slippage between the two materials. The classification requirements for steel sections and composite sections in most specifications were originally derived from experimental and analytical studies based on the the...
Full Text Available In order to study the effect of prestressed box girder webs stresss state, determining the stress distribution within a web, research and analysis of vertical prestressed box girder, curved beam prestressed sensitivity under the web. Establishing the finite element model of the box girder web vertical prestressing effect is analyzed, results show that the principal tensile stress of the web is sensitive to the vertical prestress, applying the vertical prestress can effectively reduce the principal tensile stress of the web; with the decrease of the effective vertical prestress, the neutral axis above the principal compressive stress decreases rapidly, while below the neutral axis decreases relatively slow; Under the same vertical preloading stress level, the roots of cross section of the compressive stress of web reserves than L / 4 section of the web. Calculation and analysis of curved beam under bending point, different bending angles and bending radius of principal stress effect on the web, Results show that the set of curved beam web when the curved beam bending stress concentration easily, appear the main tensile stress; Increase the bending radius can effectively reduce beam cross-section of web principal tensile stress, along with the rising of the next corner, principal tensile stress peak value increases gradually, thus setting bending beam, should try to reduce the bending angle.
Full Text Available Fiber-reinforced polymers (FRP are being increasingly used for the repair and strengthening of deteriorated or unsafe concrete structures, including structurally deficient concrete highway bridges. The behavior of FRP strengthened concrete bridge girders, including failure modes, failure loads, and deflections, can be determined using an analytical finite element modeling approach, as outlined in this paper. The differences in flexural versus shear FRP strengthening and comparison with available design guidelines are also beneficial to design professionals. In this paper, a common AASHTO type prestressed concrete bridge girder with FRP wrapping was analyzed using the ANSYS FEM software and the ACI analytical approach. Both flexural and shear FRP applications, including vertical and inclined shear strengthening, were examined. Results showed that FRP wrapping can significantly benefit concrete bridge girders in terms of flexure/shear capacity increase, deflection reduction, and crack control. The FRP strength was underutilized in the section selected herein, which could be addressed through decrease of the amount of FRP and prestressing steel used, thereby increasing the section ductility. The ACI approach produced comparable results to the FEM and can be effectively and conveniently used in design.
Full Text Available The U-shaped girder is a type of open thin-walled structure, which is used in urban rail transit engineering. Although it employs polypropylene fiber concrete to avoid cracks, the girder is still easier to crack than other traditional structures owing to its special open thin-walled cross section. In this study, a cracking accident of a U-shaped girder, which happened during the prestressed steel tensioning, was studied by field investigation and mechanical analysis through the finite element (FE method. An outline of the cracks was presented. The nonlinear material properties of the polypropylene fiber concrete and steel were discussed and used in the finite element model. The effects of the main design parameters, such as the flange slab thickness, anchorage position, and prestressed steel layout, were evaluated based on the results of the FE analysis. The results indicate that the extremely low rigidity of the web and oversize of the web longitudinal prestressed steels are the main reasons for the cracks. The risk of cracks can be reduced by increasing the thickness of the flange slab and changing the anchorage position and prestressed steel layout. Some suggestions are provided for avoiding cracks based on the results of the research.
Full Text Available Most of the previous researches conducted on shear lag of box girders were only concerned about simple types of structures, such as simply supported and cantilever beams. The structural systems concerned in these previous researches were considered as determined and unchangeable. In this paper, a finite element method considering shear lag and creep of concrete was presented to analyze the effect of dynamic construction process on shear lag in different types of concrete box-girder bridges. The shear lag effect of the three types of a two-span continuous concrete beam classified by construction methods was analyzed in detail according to construction process. Also, a three-span prestressed concrete box-girder bridge was analyzed according to the actual construction process. The shear lag coefficients and stresses on cross sections along the beam including shear lag were obtained. The different construction methods, the changes of structural system with the construction process, the changes of loading and boundary conditions with the construction process and time, the prestressing, and creep were all imitated in the calculations. From comparisons between the results for beams using different construction methods, useful conclusions were made.
Crane, Charles Kennan
Ultra-High Performance Concrete (UHPC) is a new class of concrete characterized by no coarse aggregate, steel fiber reinforcement, low w/c, low permeability, compressive strength exceeding 29,000 psi (200 MPa), tensile strength ranging from 1,200 to 2,500 psi (8 to 17 MPa), and very high toughness. These properties make prestressed precast UHPC bridge girders a very attractive replacement material for steel bridge girders, particularly when site demands require a comparable beam depth to steel and a 100+ year life span is desired. In order to efficiently utilize UHPC in bridge construction, it is necessary to create new design recommendations for its use. The interface between precast UHPC girder and cast-in-place concrete decks must be characterized in order to safely use composite design methods with this new material. Due to the lack of reinforcing bars, all shear forces in UHPC girders have to be carried by the concrete and steel fibers. Current U.S. codes do not consider fiber reinforcement in calculating shear capacity. Fiber contribution must be accurately accounted for in shear equations in order to use UHPC. Casting of UHPC may cause fibers to orient in the direction of casting. If fibers are preferentially oriented, physical properties of the concrete may also become anisotropic, which must be considered in design. The current research provides new understanding of shear and shear friction phenomena in UHPC including: (1) Current AASHTO codes provide a non-conservative estimate of interface shear performance of smooth UHPC interfaces with and without interface steel. (2) Fluted interfaces can be created by impressing formliners into the surface of plastic UHPC. AASHTO and ACI codes for roughened interfaces are conservative for design of fluted UHPC interfaces.(3) A new equation for the calculation of shear capacity of UHPC girders is presented which takes into account the contribution of steel fiber reinforcement. (4) Fibers are shown to preferentially
Full Text Available The influence on modal parameters of thin cylindrical shell (TCS under bolt looseness boundary is investigated. Firstly, bolt looseness boundary of the shell is divided into two types, that is, different bolt looseness numbers and different bolt looseness levels, and natural frequencies and mode shapes are calculated by finite element method to roughly master vibration characteristics of TCS under these conditions. Then, the following measurements and identification techniques are used to get precise frequency, damping, and shape results; for example, noncontact laser Doppler vibrometer and vibration shaker with excitation level being precisely controlled are used in the test system; “preexperiment” is adopted to determine the required tightening torque and verify fixed constraint boundary; the small-segment FFT processing technique is employed to accurately measure nature frequency and laser rotating scanning technique is used to get shape results with high efficiency. Finally, based on the measured results obtained by the above techniques, the influence on modal parameters of TCS under two types of bolt looseness boundaries is analyzed and discussed. It can be found that bolt looseness boundary can significantly affect frequency and damping results which might be caused by changes of nonlinear stiffness and damping and in bolt looseness positions.
Ho, Siu Chun Michael; Li, Weijie; Wang, Bo; Song, Gangbing
Rock bolts are the devices that used to reinforce the rock masses in mining tunnels and underground excavation structures. The loading level of the rock bolt indicates the reinforcing efficiency and is able to ensure safe underground operation by giving warnings to the underground miners prior to any accidents. Therefore, it is very important to monitor the load level of the rock bolts. In this short communication, we propose a smart anchor plate, a simple but effective device that uses fiber Bragg gratings (FBG) type optic sensor, to monitor the load level of the rock bolt. Instead of measuring the stress/strain on the rock bolt, which adds more complexity, the proposed method monitors the rock bolt load by measuring the load experience on the rock bolt anchor plate. Such a configuration has the advantages of simple structure and flexible implementation. In experimental observation, the FBG instrumented anchor plate is able to observe the load of the plate with good repeatability. This test will lead to further in-depth studies involving finite element analysis as well as more complex applications.
Full Text Available According to the frequent fractures of rock bolts in high ground pressure roadways of deep mines, this paper analyzes the mechanism of fractures and concludes that high ground pressure and material de-fects are main reasons for the fracture of rock bolts. The basic idea of fracture control of rock bolts in high ground pressure roadways of deep mines is to increase the yield load and the limit load of rock bolt materials and reduce the actual load of rock bolts. There are four ways of controlling rock bolt fracture: increasing the rock bolt diameter, strengthening bolt materials, weakening support rigidity and the implementation of double supporting. With the roadway support of the 2302 working face of a coal mine as the project background, this paper carries out a study on the effect of two schemes, increasing the rock bolt diameter and the double supporting technique through methods of theoretical analysis, numerical simulation and so on. It determines the most reasonable diam-eter of rock bolts and the best delay distance of secondary support. Practices indicate that rock bolt fracture can be effectively controlled through the double supporting technique, which strengthens the roof and two sides through the first supporting technique and strengthens side angles through the secondary supporting technique.
Miao Xie-xing; Mao Xian-biao; Zhu Chuan-qu; Liu Wei-qun [China University of Mining and Technology, Xuzhou (China)
The bolt probably supports larger shearing deformation in the course of huge deformation of roadway surrounding rock, for instance the cable bolts-metal mesh reinforcement of small pillar adopted largely in coalmines, especially that in gob-side entry of fully-mechanized caving face (FCF). The mechanism that the full-column roof support bolt sustains during shearing deformation in gob-side entry of FCF was analyzed by theoretical research, and the shearing stress distribution, the maximum shearing force and the maximum shearing stress in bolts were obtained with the help of numerical simulation. It is indicated that the maximum shearing stress of the roof support bolt in gob-side entry of FCF will approach or exceed the allowable shearing stress of bolt materials in condition of large deformation in surrounding rock, and here, the shearing effect of bolt is not to be neglected. 6 refs., 4 figs., 1 tab.
Weigand, Jonathan M.; Berman, Jeffrey W.
Large-scale tests of steel gravity framing systems (SGFSs) have shown that the connections are critical to the system integrity, when a column suffers damage that compromises its ability to carry gravity loads. When supporting columns were removed, the SGFSs redistributed gravity loads through the development of an alternate load path in a sustained tensile configuration resulting from large vertical deflections. The ability of the system to sustain such an alternate load path depends on the capacity of the gravity connections to remain intact after undergoing large rotation and axial extension demands, for which they were not designed. This study experimentally evaluates the performance of steel bolted angle connections subjected to loading consistent with an interior column removal. The characteristic connection behaviors are described and the performance of multiple connection configurations are compared in terms of their peak resistances and deformation capacities. PMID:27110059
Full Text Available Continuous girder bridges become increasingly popular because of the rapid development of highway throughout the world. Most of previous researches on vibration analysis of a multispan continuous bridge subject to complex traffic loading and vehicle dynamic interaction focus on the girder displacement not considering braking effects. In current literature, few studies have discussed the effects of braking on continuous girder bridges. In this study, we employ the finite element method (FEM to investigate the dynamic response of continuous girder bridge due to three-axle vehicle. Vertical reaction forces of axles that change with time make bending vibration of girder increase significantly. The braking in the first span is able to create response in other spans. In addition, the dynamic impact factors are investigated by both FEM and experiments on a real bridge structure. The results of this study extend the current understanding of the bridge dynamic behaviors and can be used as additional references for bridge codes by practicing engineers.
Full Text Available The maglev vehicle-girder coupled vibration problem has been encountered in many maglev test or commercial lines, which significantly degrade the performance of the maglev train. In previous research on the principle of the coupled vibration problem, it has been discovered that the fundamental model of the maglev girder can be simplified as a series of mass-spring resonators of different but related resonance frequencies, and that the stability of the vehicle-girder coupled system can be investigated by separately examining the stability of each mass-spring resonator – electromagnet coupled system. Based on this conclusion, a maglev test platform, which includes a single electromagnetic suspension control system, is built for experimental study of the coupled vibration problem. The guideway of the test platform is supported by a number of springs so as to change its flexibility. The mass of the guideway can also be changed by adjusting extra weights attached to it. By changing the flexibility and mass of the guideway, the rules of the maglev vehicle-girder coupled vibration problem are to be examined through experiments, and related theory on the vehicle-girder self-excited vibration proposed in previous research is also testified.
Jeong, Woo Tae; Kim, Suk Tae; Sohn, Wook; Kang, Duk Won; Kang, Seok Chul
To develop a system for visually inspecting the flow distribution plate (FDP) bolts of a nuclear steam generator, we reviewed several types of similar inspection equipment. The equipment which are currently available are mostly for inspecting lower part of a steam generator such as tube sheets and annulus except ELVS (Eggcrate Visual Inspection System). However, the design concept of ELVS could not be used for developing a device which enables the visual inspection of flow distribution plate bolts. Therefore, based on the current state of the art technology on the similar equipment, we conceptually designed a new inspection system for checking the FDP bolts
Full Text Available Numerical procedure based on finite element method (FEM and finite difference method (FDM for the analysis of bolt-grout interactions are introduced in this paper. The finite element procedure incorporates elasto-plastic concepts with Hoek and Brown yield criterion and has been applied for rock mass. Bolt-grout interactions are evaluated based on finite difference method and are embedded in the elasto-plastic procedures of FEM. The experimental validation of the proposed FEM-FDM procedures and numerical examples of a bolted tunnel are provided to demonstrate the efficacy of the proposed method for practical applications.
Full Text Available This paper describes a novel composite tubular truss bridge with concrete slab and concrete-filled rectangular chords. With concrete slab plus truss system and joints reinforced with concrete and Perfobond Leiste rib, double composite truss bridge proved to be a fairly suitable solution in negative moment area. Perfobond Leiste shear connector (PBL is widely implemented in the composite structure for its outstanding fatigue resistance. In this pilot bridge, Perfobond Leister ribs (PBR were installed in the truss girder's joints, which played double roles as shear connector and stiffener. An erection method and overall bridge structural analysis were then presented. Typical joints in the pilot bridge were selected to analyze the effect of PBR. Investigation of the effect of PBR in concrete-filled tubular joints was elaborated. Comparison has revealed that concrete-filled tubular joints with PBR have much higher constraint capability than joints without PBR. For rectangular tubular truss, the punching shear force of the concrete filled joint with PBR is approximately 43% larger than that of the joint without PBR. Fatigue performance of the joint installed with PBR was improved, which was found through analysis of the stress concentration factor of joint. The PBR installed in the joints mitigated the stress concentration factor in the chord face. Therefore, the advantages of this new type of bridge are demonstrated, including the convenience of construction using rectangular truss, innovative concept of structural design and better global and local performances.
Mehlhorn, Alexander T; Walther, Markus; Iblher, Niklas
. There was a significant association between preoperative increased Hba1c value, presence of preoperative ulcer and wound infection. Healing of arthrodesis was demonstrated in 57% and a permanent weight-bearing foot without recurrent ulcer was achieved in 79%. The early and late postoperative complications could....... Since bolt dislocation takes place frequently, it was aimed to predict an appropriate time point for bolt removal under the condition that osseous healing has occurred. Fourteen consecutive patients with neuroosteoarthropathy of the foot and arch collapse were treated with open reduction...... and stabilization using midfoot fusion bolt and lateral lag screws. Age, gender, presence of preoperative osteomyelitis or ulcer, number of complications and operative revisions, Hba1c value, consolidation of arthrodesis, presence of a load-bearing foot and period to bolt dislocation was assessed. The mean follow...
Chen Feng; Li Tianjin; Zhang Zhengming; Huang Zhiyong; Bo Hanliang
The absorption sphere shutdown system performs an important role in reactivity regulating and control. Driving mechanism is a set of key mechanical moving parts which is used to control falling of absorption spheres in absorption sphere shutdown system. It is about 5 m for driving mechanism with the slim structure, which is connected with the upper supported plate of metal reactor internals through storage vessel with bolts. Both the storage vessel and driving mechanism are equipment of seismic classification I. It is significant to calculate and check the bolts strength of driving mechanism. In this paper, complicate structure of driving mechanism was simplified to three variable cross sections and statically indeterminate problem was solved. The bolts at the bottom and on the top of the storage vessel were calculated and checked. The preliminary results indicate that the bolts strength is reliable and safe, and the supporting force at the most weak point of driving mechanism is as well obtained. (authors)
Finkelstein, Nir; Volkov, Nikolai; Novoselsky, Yehuda; Tsach, Tsadok
Bolt cutters are known as devices which are used for cutting hard objects and rigid materials such as padlocks and bars. They are commonly used in instances of forced entries. In this case study, a bolt cutter was found in the car of two suspects in a grocery burglary. This study indicates how the presence of a small metallic chip found on a suspected bolt cutter can prove that the tool was used in the crime scene. During the initial examination, a metallic chip from the cut shackle padlock was found stuck to one of the bolt cutters' blades. By comparing the metallic chip's microscopic edge and the breaking (fracture) line of the padlock's shackle, a full physical match was noticed. We wish to report here how residue, even the smallest, can be used to link burglary tools to a crime scene with a high level of certainty. © 2015 American Academy of Forensic Sciences.
Nelson, W. D.; Bunin, B. L.; Hart-Smith, L. J.
A program was conducted at Douglas Aircraft Company to develop the technology for critical structural joints of composite wing structure that meets design requirements for a 1990 commercial transport aircraft. The prime objective of the program was to demonstrate the ability to reliably predict the strength of large bolted composite joints. Ancillary testing of 180 specimens generated data on strength and load-deflection characteristics which provided input to the joint analysis. Load-sharing between fasteners in multirow bolted joints was computed by the nonlinear analysis program A4EJ. This program was used to predict strengths of 20 additional large subcomponents representing strips from a wing root chordwise splice. In most cases, the predictions were accurate to within a few percent of the test results. In some cases, the observed mode of failure was different than anticipated. The highlight of the subcomponent testing was the consistent ability to achieve gross-section failure strains close to 0.005. That represents a considerable improvement over the state of the art.
Broccanello, Chiara; Stevanato, Piergiorgio; Biscarini, Filippo; Cantu, Dario; Saccomani, Massimo
Premature flowering or bolting is an undesirable characteristic that causes severe sugar yield losses and interferes with harvesting. Vernalization is a prerequisite for the floral induction, achieved by exposure to low temperatures for 10-14 weeks. This process is also controlled by other environmental factors, such as long daylight photoperiods and a combination of genetic factors. The objective of this study was the identification of new genetic polymorphisms linked to bolting tendency in sugar beet. Two pollinators characterized by low and high bolting tendency were subjected to RAD-sequencing in order to detect discriminating SNPs between lines. 6,324 putative SNPs were identified. Of these, 192 were genotyped in a set of 19 pollinators, each comprising bolted and non-bolted individuals, for a total of 987 samples. Among the 192 candidate SNPs, the strongest overall association was found for SNP183 on chromosome 6 (p-value = 1.246 10(-13)). The association between SNP183 and bolting tendency was then confirmed in an independent population of 730 plants from 11 breeding lines (p-value = 0.0061). SNP183 is located in the intron of Bv_22330_orky, a sugar beet homolog of a matrix metalloproteinase (MMP) gene that could be implied in flowering in Arabidopsis thaliana. Our data support a significant association between an intronic SNP in the MMP gene located on chromosome 6 and the regulation of bolting tendency in sugar beet. The newly identified locus supports the polygenic nature of flowering control. The associated marker can be used to design SNP panels for the discrimination of bolters and non-bolters, to be used in sugar beet breeding programs for the development of improved germplasm with low bolting tendency.
Miao Xueliang; Luan Xingfeng; Zhang Wei; Bian Chunhua; Yu Xiaoyan; Xu Ke; Liu Hongqun
Through on the fan anchor bolt material components, metallurgical structure and fracture analysis indicates that: material composition and microscopic are abnormal, it led to material brittle increased, the fracture is rock-candy structure, the last part is toughness structure. The reason is the the fan vibrate oversize. At last, we put forward some measures. Just like, control the vibration of the fan, set a nominal tightening torque when installing bolt. (authors)
Kozel, A.M. (VNIMI (USSR))
Evaluates interaction of roof bolts used in mine shafts and the surrounding strata. Effects of stratification, mechanical rock properties, state of initial tension, developing fissures and cracks are comparatively evaluated. Time effects on state of stress of the strata surrounding a mine shaft are analyzed. Stress relaxation and its effects on interaction of roof bolts and the rock strata are investigated. Formulae that describe this interaction are derived. 7 refs.
Al-Azzawi, Zaid; Stratford, Timothy; Rotter, John; Bisby, Luke
The two essential functions of the web plate in a plate girder are to maintain a relative distance between the top and bottom flanges and to resist shear stresses. In most practical ranges of plate girder bridge spans, the shear stresses are relatively low compared to bending stresses in the flanges induced by flexure. As a result, the web plate is typically much thinner than the flanges. The web panel is therefore prone to buckling at comparatively low shear forces. To enhance the web’s buck...
Jhang, Kyung-Young; Quan, Hai-Hua; Ha, Job; Kim, Noh-Yu
The estimation of clamping force has been regarded as the main issue in the maintenance of high-tension bolts. This paper proposes a method which uses the dependency of ultrasonic velocity on stress based on the nonlinear elastic effect. The variation of ultrasonic velocity in the range of actual stress acting in the bolt is very small so that the precise measurement of ultrasonic velocity is needed. In this paper, we adopt a method to measure ultrasonic velocity, where the TOF (time of flight) of a tone-burst ultrasonic wave is precisely measured by using the phase detection technique. In order to verify the usefulness of the proposed method, two kinds of experiments are carried out. The first one measures ultrasonic velocity when the bolt is stressed by the tension tester, and from this, the exact axial force acting in the bolt can be determined. The results show good agreement with the expected linear relationship between ultrasonic velocity and axial stress. The second experiment measures ultrasonic velocity when the bolt is stressed by the torque wrench. The results show that ultrasonic velocity decreased as the torque increased, which is identical to the theoretically expected tendency. From these results, it can be said that the proposed method is adequate in evaluating clamping force in high-tension bolts.
Cheng, Liang; Zhang, Yidong; Ji, Ming; Zhang, Kai; Zhang, Minglei
Roadways supported by bolts contain support structures that are built into the rock surrounding the roadway, referred to as reinforced rocks in this paper. Using physical model simulation, the paper investigates the bearing characteristics of the reinforced rock under different bolt parameters with incrementally increased load. The experimental results show that the stress at the measurement point inside the structure varies with the kinetic pressure. The stress increases slowly as the load is initially applied, displays accelerated growth in the middle of the loading application, and decreases or remains constant in the later stage of the loading application. The change in displacement of the surrounding rock exhibits the following characteristics: a slow increase when the load is first applied, accelerated growth in the middle stage, and violent growth in the later stage. There is a good correlation between the change in the measured stress and the change in the surrounding rock displacement. Increasing the density of the bolt support and the length and diameter of the bolt improves the load-bearing performance of the reinforced rock, including its strength, internal peak stress, and residual stress. Bolting improves the internal structure of the surrounding rocks, and the deterioration of the surrounding rock decreases with the distance between the bolt supports.
Full Text Available This study establishes an analytical model for the interaction between the bolt and surrounding rock based on the bearing mechanism of fully grouted rock bolts. The corresponding controlled differential equation for load transfer is deduced. The stress distributions of the anchorage body are obtained by solving the equations. A dynamic algorithm for the bolt considering shear damage on the anchoring interface is proposed based on the dynamic finite element method. The rationality of the algorithm is verified by a pull-out test and excavation simulation of a rounded tunnel. Then, a case study on the mechanical characteristics of the bolts in underground caverns under seismic loads is conducted. The results indicate that the seismic load may lead to stress originating from the bolts and damage on the anchoring interface. The key positions of the antiseismic support can be determined using the numerical simulation. The calculated results can serve as a reference for the antiseismic optimal design of bolts in underground caverns.
Full Text Available Bolts support have become a major active support method in coal mine roadways to control roadway roof failure and improve surrounding rock structure stability. The traditional bolt force status monitoring (BFSM method has poor anti-interference performance, is easily affected by harsh downhole environments, and cannot support remote real-time monitoring. This paper presents a fiber Bragg grating (FBG bolt force sensor that monitors the force of roadway bolts. This sensor uses a cantilever and a diaphragm as elastic elements and two FBGs bonded on the top and bottom surfaces of the cantilever as sensing elements. The experimental results indicate that the measuring sensitivity is improved by using the center wavelength difference between the two FBGs. The sensitivity is 38.79 pm/kN within the range from 0 to 150 kN, and the correlation coefficient reaches 99.98%. The engineering applications show that the FBG sensing technology can automatically acquire, and monitoring results are of great significance in roadway anchorage engineering safety and bolt support quality evaluation. Furthermore, such a sensor is also widely used in quasi-distributed measurement and long-term online monitoring of bolt force status in such fields as geotechnical engineering, tunnel engineering, and slope engineering.
Mattar Neto, Miguel; Miranda, Carlos A.J.; Fainer, Gerson
The spent fuel elements transportation packages must be designed for severe conditions including significant fire and impact loads corresponding to hypothetical accident conditions. In general, these packages have large flat lids connected to cylindrical bodies by closure bolts that can be the weak link in the containment system. The bolted closure design depends on the geometrical characteristics of the flat lid and the cylindrical body, including their flanges, on the type of the gaskets and their dimensions, and on the number, strength, and tightness of the bolts. There are well established procedures for the closure bolts design used in pressure vessels and piping. They can not be used directly in the bolts design applied to transportation packages. Prior to the use of these procedures, it is necessary consider the differences in the main loads (pressure for the pressure vessels and piping and impact loads for the transportation packages) and in the geometry (large flat lids are not used in pressure vessels and piping). So, this paper presents an approach for the design of the closure bolts of spent fuel elements transportation packages considering the impact loads and the typical geometrical configuration of the transportation packages. (author)
Massudi, H.; Yeh, H.Y.; Thomas, G.D. II; Zhang, S.
The overall intent of this study is to establish a much-needed basis for a criteria to evaluate and validate the performance of plutonium storage containers during their life span. At present, there is no such information about these containers in existence. Therefore, it is the mission to acquire and accumulate as much data relevant to the mechanical properties of plutonium storage containers as possible. By establishing a database of information about physical attributes, it will be possible for future researchers to sight any change in properties, as affected by time. Thus, the first phase of investigation and physical testing will be to characterize and isolate behaviors related to tribology, and measure physical attributes of the container, as necessary. There is a need to measure each component and dimension to sight irregularities and inconsistencies, for calculation of average values, used to conduct accurate theoretical analysis. There are numerous factors to consider when analyzing the mechanical properties of plutonium storage containers. Perhaps the most important variables to consider, that will determine the success of the container in-service, is tribological behavior. Variables, which contribute to friction, wear and corrosion affect the flange and the components attached directly and must be thoroughly investigated to determine the acceptability of the plutonium storage container
Creep and relaxation occur after HTB tightening causing shaft tension loss and further stress redistribution in the connected components. Past research has shown that waisting the HTB shaft diameter reduces stress concentrations, shaft tension loss and increases ductility. With the further modification of making the HTB ...
Kim, Seung Dae
Post-tensioned cast-in-place concrete box girder bridges are the most popular type for new bridge construction in California since this class of bridges shows an increased ability to resist and dissipate seismic loads for long- span structures. However, due to the long-term behavior of the construction materials .i.e. concrete and steel, tension forces induced by prestressing decrease over time as a result of creep and shrinkage of concrete and steel relaxation, which is called long-term pres...
Full Text Available In this paper, the behavior of the intertwined shear and patch loading mechanisms in transversally stiffened steel plate girders is described. The phenomenological insight depicted in this paper shows the influence of the web thickness and the flange yield strength as well as the influence of the transverse stiffeners on the stress distribution, the critical loads and on the equilibrium path of this particular type of loading. A previously validated numerical model is used systematically as a simulation tool. Stress-, strain-, force- and displacement fields are exploited for the sake of inferring and idealizing the most valuable features of the depicted mechanical model.
Horyl, P.; Šňupárek, Richard; Maršálek, P.
Roč. 59, č. 3 (2014), s. 723-734 ISSN 0860-7001 R&D Projects: GA MŠk ED2.1.00/03.0082; GA MŠk ED1.1.00/02.0070 Institutional support: RVO:68145535 Keywords : steel arch yielding support * friction al joints * bolt connection * slip support * fem Subject RIV: DH - Mining, incl. Coal Mining Impact factor: 0.608, year: 2013
Full Text Available Based on the health monitoring system installed on the main span of Sutong Cable-Stayed Bridge, GPS displacement and wind field are real-time monitored and analyzed. According to analytical results, apparent nonlinear correlation with certain discreteness exists between lateral static girder displacement and lateral static wind velocity; thus time series of lateral static girder displacement are decomposed into nonlinear correlation term and discreteness term, nonlinear correlation term of which is mathematically modeled by third-order Fourier series with intervention of lateral static wind velocity and discreteness term of which is mathematically modeled by the combined models of ARMA(7,4 and EGARCH(2,1. Additionally, stable power spectrum density exists in time series of lateral dynamic girder displacement, which can be well described by the fourth-order Gaussian series; thus time series of lateral dynamic girder displacement are mathematically modeled by harmonic superposition function. By comparison and verification between simulative and monitoring lateral girder displacements from September 1 to September 3, the presented mathematical models are effective to simulate time series of lateral girder displacement from main girder of Sutong Cable-Stayed Bridge.
The project European Development Rockbolting which was developed during the period 1994-1997 and carried out within the OCICARBON Action Program (OCICARBON-ITGE agreement dated September 1, 1994, Code C-13-438) as well as within the framework of the Coal Technical research Program of the D. G. XVII of the EEC, n 7220/AB/143. The project has had the following external partners: DMT (Germany), BCC (UK) and CDF (France), and the collaboration of INERIS (France), RMT (UK) and GEOCONTROL S. A. (Spain). The objective of the investigation was to improve the techniques and design currently used in the application of rockbolts for supporting of both infrastructure and beds in the European coal mining. The most important result, besides that derived from the sharing of experiences and knowledge, was the technological design of a supporting system, which was carried out by each partner for the various proposed exploitations. The Spanish part carried out the works of designing and estimation of the bolting system corresponding to the exploitations of: -Carbones de Pedraforca SA. Saldes mine. -U. E. Provence. Pit Y. Morandat.
Muhammad Nasir Amin
Full Text Available Structural hollow sections are gaining worldwide importance due to their structural and architectural advantages over open steel sections. The only obstacle to their use is their connection with other structural members. To overcome the obstacle of tightening the bolt from one side has given birth to the concept of blind bolts. Blind bolts, being the practical solution to the connection hindrance for the use of hollow and concrete filled hollow sections play a vital role. Flowdrill, the Huck High Strength Blind Bolt and the Lindapter Hollobolt are the well-known commercially available blind bolts. Although the development of blind bolts has largely resolved this issue, the use of structural hollow sections remains limited to shear resistance. Therefore, a new modified version of the blind bolt, known as the "Extended Hollo-Bolt" (EHB due to its enhanced capacity for bonding with concrete, can overcome the issue of low moment resistance capacity associated with blind-bolted connections. The load transfer mechanism of this recently developed blind bolt remains unclear, however. This study uses a parametric approach to characterising the EHB, using diameter as the variable parameter. Stiffness and load-carrying capacity were evaluated at two different bolt sizes. To investigate the load transfer mechanism, a component-based study of the bond and anchorage characteristics was performed by breaking down the EHB into its components. The results of the study provide insight into the load transfer mechanism of the blind bolt in question. The proposed component-based model was validated by a spring model, through which the stiffness of the EHB was compared to that of its components combined. The combined stiffness of the components was found to be roughly equivalent to that of the EHB as a whole, validating the use of this component-based approach.
Background Bolting reduces the quality and commercial yield of Welsh onion (Allium fistulosum L.) in production. However, seed production is directly dependent on flower induction and bolting. The Welsh onion belongs to the green plant vernalisation type, specific seedling characteristics and sufficient accumulated time at low temperature are indispensible for the completion of its vernalisation process. Only if these conditions for vernalisation are fulfilled, the plants will bolt in the following year. The present investigation evaluated the effects of cultivar, sowing date and transplant location in field on the bolting of Welsh onion at the Horticultural Farm of the College of Horticulture, Northwest A&F University, Yangling, Shannxi Province, China in two succeeding production years: 2010–2011 and 2011–2012. A strip split plot layout within a randomised complete block design with three replications was used. Results The results revealed that all three factors (cultivar, sowing date and transplant location) and their interaction had significant effects on the initiation and final rate of bolting observed by 30 April. The earliest bolting date (14 February, 2011 and 15 February, 2012) and the highest bolting rate (100% in 2011 and 62% in 2012) occurred when the JinGuan cultivar was sown on 20 August and transplanted in a plastic tunnel, whereas the latest date and lowest rate (no bolting observed until 30 April) of bolting occurred when the XiaHei cultivar was sown on 29 September and transplanted in an open field. Conclusions These results suggest that we can control bolting in Welsh onion production by choosing an appropriate cultivar, sowing date and transplant location. Choosing a late bolting cultivar, such as cultivar XiaHei, sowing around October, and transplanting in the open field can significantly delay bolting, while a sowing date in late August should be selected for seed production, and the seedlings should be transplanted in a plastic tunnel to
Full Text Available AbstractThe transition of vegetative growth to bolting and flowering is an important process in the life cycle of plants, which is determined by numerous genes forming an intricate network of bolting and flowering. However, no comprehensive identification and profiling of bolting and flowering-related genes have been carried out in radish. In this study, RNA-seq technology was applied to analyze the differential gene expressions during the transition from vegetative stage to reproductive stage in radish. A total of 5,922 differentially expressed genes (DEGs including 779 up-regulated and 5,143 down-regulated genes were isolated. Functional enrichment analysis suggested that some DEGs were involved in hormone signaling pathways and the transcriptional regulation of bolting and flowering. KEGG-based analysis identified 37 DEGs being involved in phytohormone signaling pathways. Moreover, 95 DEGs related to bolting and flowering were identified and integrated into various flowering pathways. Several critical genes including FT, CO, SOC1, FLC and LFY were characterized and profiled by RT-qPCR analysis. Correlation analysis indicated that 24 miRNA-DEG pairs were involved in radish bolting and flowering. Finally, a miRNA-DEG-based schematic model of bolting and flowering regulatory network was proposed in radish. These outcomes provided significant insights into genetic control of radish bolting and flowering, and would facilitate unraveling molecular regulatory mechanism underlying bolting and flowering in root vegetable crops.
Jensen, Find Mølholt; Branner, Kim; Nielsen, Per Hørlyk
This report presents the setup and result of a full-scale test of a reinforced glass fibre/epoxy box girder used in 34m wind turbine blade. The tests were performed at the Blaest test facility in August 2006. The test is an important part of a research project established in cooperation between...... Risø DTU, the National Laboratory for Sustainable Energy at the Technical University of Denmark -, SSP-Technology A/S and Blaest (Blade test centre A/S) and it has been performed as a part of Find Mølholt Jensen‟s PhD study. This report contains the complete test data for the final test, in which...... the box girder was loaded until failure. A comprehensive description of the test setup is given. This report deals only with tests and results. There are no conclusions on the data in this report, but references are given to publications, where the data are used and compared with FEM etc. Various kinds...
Curved steel bridges are commonly used at interchanges in transportation networks and more of these structures continue to be designed and built in the United States. Though the use of these bridges continues to increase in locations that experience high seismicity, the effects of curvature and other parameters on their seismic behaviors have been neglected in current risk assessment tools. These tools can evaluate the seismic vulnerability of a transportation network using fragility curves. One critical component of fragility curve development for curved steel bridges is the completion of sensitivity analyses that help identify influential parameters related to their seismic response. In this study, an accessible inventory of existing curved steel girder bridges located primarily in the Mid-Atlantic United States (MAUS) was used to establish statistical characteristics used as inputs for a seismic sensitivity study. Critical seismic response quantities were captured using 3D nonlinear finite element models. Influential parameters from these quantities were identified using statistical tools that incorporate experimental Plackett-Burman Design (PBD), which included Pareto optimal plots and prediction profiler techniques. The findings revealed that the potential variation in the influential parameters included number of spans, radius of curvature, maximum span length, girder spacing, and cross-frame spacing. These parameters showed varying levels of influence on the critical bridge response.
Full Text Available Precast, prestressed concrete box girders are commonly used as superstructure components for short and medium span bridges. Their configuration and typical side-by-side placement make large portions of these elements inaccessible for visual inspection or the application of nondestructive testing techniques. This paper demonstrates that vibration-based damage detection (VBDD is an effective alternative for monitoring their structural health. A box girder removed from a dismantled bridge was used to evaluate the ability of five different VBDD algorithms to detect and localize low levels of spalling damage, with a focus on using a small number of sensors and only the fundamental mode of vibration. All methods were capable of detecting and localizing damage to a region within approximately 1.6 times the longitudinal spacing between as few as six uniformly distributed accelerometers. Strain gauges configured to measure curvature were also effective, but tended to be susceptible to large errors in near support damage cases. Finite element analyses demonstrated that increasing the number of sensor locations leads to a proportional increase in localization accuracy, while the use of additional modes provides little advantage and can sometimes lead to a deterioration in the performance of the VBDD techniques.
Full Text Available Based on the nonlinear stability analysis method, the 3D nonlinear finite element model of a composite girder cable-stayed bridge with three pylons is established to research the effect of factors including geometric nonlinearity, material nonlinearity, static wind load, and unbalanced construction load on the structural stability during construction. Besides, the structural nonlinear stability in different construction schemes and the determination of temporary pier position are also studied. The nonlinear stability safety factors are calculated to demonstrate the rationality and safety of construction schemes. The results show that the nonlinear stability safety factors of this bridge during construction meet the design requirement and the minimum value occurs in the maximum double cantilever stage. Besides, the nonlinear stability of the structure in the side of edge-pylon meets the design requirement in the two construction schemes. Furthermore, the temporary pier can improve the structure stability, effectively, and the actual position is reasonable. In addition, the local buckling of steel girder occurs earlier than overall instability under load in some cable tension stages. Finally, static wind load and the unbalanced construction load should be considered in the stability analysis for the adverse impact.
Full Text Available This paper introduces a novel quay crane design, double girder bridge crane (DGBC. DGBC is capable of handling containers of two adjacent bays simultaneously, avoiding crane collisions, saving travelling and reposition cost, and eventually improving terminal efficiency. This problem is formulated as a resource-constrained project scheduling with objective to minimize the maximum completion time. A two-stage heuristic algorithm is proposed in which an operating sequences on each bay is obtained by double cycling, and the integrated timetable for both bays is constructed by solving resource conflicts using the proposed minimum cost strategy. We examine effectiveness and performance of applying DGBC with double cycling. A case study is presented to illustrate how DGBC works with the two-stage method. Three extreme cases with respective conflict types are investigated to develop the performance bounds of DGBC with double cycling. The results show that DGBC can significantly improve terminal productivity, and outperforms single girder crane in both makespan and the lift operation percentage. The highest DGBC efficiency does not require maximum double cycles in two bay schedules; rather the integrated timetable for two bays is the main contribution to the DGBC performance as it yields better cooperation between two spreaders and the driver.
Balhan, B; Rizzo, A; Weterings, W; CERN. Geneva. SPS and LHC Division
For the extraction of the beam from the Super Proton Synchrotron (SPS) to ring 2 of the Large Hadron Collider (LHC) and the CERN Neutrino to Gran Sasso (CNGS)facility, a new fast-extraction system is being constructed in the long straight section LSS4 of the SPS. Besides extraction bumpers, enlarged aperture quadrupoles and extraction kicker magnets (MKE), six conventional DC septum magnets (MSE) are used. These magnets are mounted on a single rigid support girder, pre-aligned so as to follow the trajectory of the extracted beam and optimise the available aperture. The girder has been motorised in order to optimise the local SPS aperture during setting up, so as to avoid the risk of circulating beam impact on the septum coils. In this note, we briefly present the trajectory and apertures of the beam, we describe the calculations and methods that have been used to determine the magnet position on the girder, and finally we report on the details of the girder movement and alignment.
Sievers, Daniel E.; Warden, Harry K.
A key mechanism used in the on-orbit assembly of the International Space Station (ISS) pressurized elements is the Common Berthing Mechanism. The mechanism that effects the structural connection of the Common Berthing Mechanism halves is the Powered Bolt Assembly. There are sixteen Powered Bolt Assemblies per Common Berthing Mechanism. The Common Berthing Mechanism has a bolt which engages a self aligning Powered Bolt Nut (PBN) on the mating interface (Figure 1). The Powered Bolt Assemblies are preloaded to approximately 84.5 kN (19000 lb) prior to pressurization of the CBM. The PBNs mentioned below, manufactured in 2009, will be used on ISS future missions. An on orbit functional failure of this hardware would be unacceptable and in some instances catastrophic due to the failure of modules to mate and seal the atmosphere, risking loss of crew and ISS functions. The manufacturing processes that create the PBNs need to be strictly controlled. Functional (torque vs. tension) acceptance test failures will be the result of processes not being strictly followed. Without the proper knowledge of thread tolerances, fabrication techniques, and dry film lubricant application processes, PBNs will be, and have been manufactured improperly. The knowledge gained from acceptance test failures and the resolution of those failures, thread fabrication techniques and thread dry film lubrication processes can be applied to many aerospace mechanisms to enhance their performance. Test data and manufactured PBN thread geometry will be discussed for both failed and successfully accepted PBNs.
Wei, Heming; Zhao, Xuefeng; Li, Dongsheng; Zhang, Pinglei; Sun, Changsen
Corrosion of rock bolts is a major cause for deterioration of the anchor-reinforced concrete slopes structures. In order to evaluate this corrosion-based deterioration in an early stage, a nondestructive technique was required. However, until now, there are no commercialized solutions that are straightforwardly available. Here, a low-coherent fiber-optic sensing technique was developed. This method can carry out the monitoring of the corrosion-caused expansion at the accuracy of sub-microstrains by circled the sensing optical fiber in two ways. One was wound the fiber on the surface of steel rock bolt directly, and thereby generated a nonuniformity in the interface of cement with rock bolt. The other was circled the fiber on a cement mortar cushion without destroying the interface any way. The sensing fiber was configured as one arm of the fiber-optic Michelson interferometer. The acceleration corrosion experiments demonstrated that a uniform interface between cement and rock bolt determined the progress of corrosion development. An early stage evaluation of the corrosion development in rock bolts was monitored.
Jang, Kyung Young; Cheon, Hae Wha; Ha, Hob; Park, Man Sick; Kim, No You
High tension bolts have been used widely for the clamping of many kinds of large structure. Therefore, its estimation has been regarded as main issue in the maintenance of high tension bolts. This paper proposes a novel method using the ultrasonic nonlinearity, which is based on the dependency of sound speed on the stress. For this we introduce nonlinear elastic constants in the stress-strain relationship, and derive the sound speed as a linear function of stress. In order to verify the usefulness of the proposed method, two kinds of experiments are carried out: The first one is to measure the sound speed when the bolt is stressed by the tension tester. The result showed good agreement with the expected linear relationship between the sound speed and the axial stress. The second one is to measure the sound speed when the bolt is stressed by the torque wrench. The results showed that the sound speed was decreased when the torque was increased. From these results we can say that the proposed method is enough useful to evaluate the clamping force in the high tension bolt.
Full Text Available Abstract Bolted end-plate steel connections have become more popular due to ease of fabrication. This paper presents a three dimension Finite Element Model (FEM, using the multi-purpose software ABAQUS, to study the effect of different geometrical parameters on the ultimate behavior of the connection. The proposed model takes into account material and geometrical non-linearities, initial imperfection, contact between adjacent surfaces and the pretension force in the bolts. The Finite Element results are calibrated with published experimental results ''briefly reviewed in this paper'' and verified that the numerical model can simulate and analyze the overall and detailed behavior of different types of bolted end-plate steel connections. Using verified FEM, parametric study is then carried out to study the ultimate behavior with variations in: bolt diameter, end-plate thickness, length of column stiffener, angle of rib stiffener. The results are examined with respect to the failure modes, the evolution of the resistance, the initial stiffness, and the rotation capacity. Finally, the ultimate behavior of the bolted end-plate steel connection is discussed in detail, and recommendations for the design purpose are made.
Correll, Francis D.; Cole, Lord K.; Slater, Charles J.; Vanhoy, Jeffrey R.; Fithian, Charles H.
HMB DeBraak was a 16-gun British brig-sloop that sank in a squall on May 25, 1798 off Cape Henlopen, Delaware. Silt covered the wooden hull shortly after it sank, preserving it until DeBraak was raised in 1986. The items recovered from the ship include metal bolts that held the hull together. We used PIXE to measure the compositions of 45 of the bolts and found that they are nearly pure copper (98.3% on average), with most also containing small amounts of iron (0.87%), nickel (0.039%), arsenic (0.43%), silver (0.089%), lead (0.18%), and bismuth (0.12%). A few contain a little indium, tin, or antimony, but none contain zinc above the quantization level. The compositions are similar to those reported for 18th-century English copper, but different from several copper alloys also used to make hull bolts. We conclude that, when DeBraak was last fitted out in 1795-1797, the Royal Navy was still using bolts similar to William Forbes's mechanically hardened pure copper bolts. Forbes's process represents the successful innovation and application of new technology in Royal Navy ships during the wars of the late 18th century.
Stock, M.; Lapierre, J. L.; Krehbiel, P. R.; Stanley, M. A.; Rison, W.; Edens, H. E.
A continuous-sampling, broadband VHF Digital Interferometer (DITF) has been operated at Langmuir Laboratory in New Mexico since 2011. For the 2013 storm season, a number of upgrades have been made to the DITF to increase the dynamic range of its front end receiver, allow for the recording of pretrigger data, and improve the trigger efficiency. The result of these upgrades are high quality interferometric maps of lightning having sub-microsecond time resolution, showing details of the physical processes within lightning flashes that previously have been difficult to observe. As an example of the DITF's data, a hybrid negative cloud-to-ground flash from a storm on July 8, 2013 is examined in detail. The flash was a classic bolt-from-the-blue that began with upward negative breakdown into upper positive storm charge, then traveled several kilometers horizontally and directly over top of the interferometer site before exiting the side of the storm and turning downward toward ground as a stepped leader. Due to the large horizontal displacement between the positive and negative ends of the breakdown channels, and to its close proximity to the interferometer site, this flash makes for an ideal case study of several different physical processes in lightning flashes including: the characteristics and properties of the positive incloud breakdown prior to and following the initial return stroke, negative leader propagation into the upper positive charge region and subsequent alteration of the leader as it progressed downward toward ground, and retrograde negative breakdown processes along the positive leader channels leading to the development of dart leaders and subsequent strokes to ground. The high time resolution of the interferometric maps makes it possible to present these processes as high quality animations similar to *those* of high speed optical observations.
This research investigated the durability of carbon fiber-reinforced polymer composites (CFRP) used for shear strengthening reinforced concrete deck girders. Large beams were used to avoid accounting for size effects in the data analysis. The effort ...
Hayman, Brian; Berggreen, Christian; Lundsgaard-Larsen, Christian
In many naval ships of fibre composite sandwich construction, an X-joint exists where the end bulkhead of the superstructure is attached to the deck, with an internal bulkhead placed in the same vertical plane below the deck. This joint is subjected to alternating tensile and compressive loading...... in the vertical direction for respectively hogging and sagging bending deformation of the hull girder. When the core material is polymer foam, such joints are often strengthened by the insertion of a higher density core material in the deck panel in the immediate region of the joint. The paper aims to improve...... the basis for the design of such X-joints, focusing on the prevention of crushing of the core under compressive load while ensuring adequate damage tolerance for the case of tensile load. Extensive material tests are reported, strain distributions are investigated by both laboratory tests and numerical...
Slott Jensen, Torben; Carlsen, Jakob Gram; Sørensen, Jens Christian
) and complications including unintended removal, catheter obstruction, infection, CSF leakage, and mechanical problems. RESULTS: A total of 271 patients with 272 separate EVDs met the inclusion criteria. There was a statistically higher rate of complications leading to reinsertion in the tunneled EVD group (40...... %), compared to the bolt-connected EVD group (6.5 %). There was no significant difference in infection rates. CONCLUSIONS: Tunneled EVD has a relatively high frequency of complications leading to reinsertion. The use of Bolt-connected EVD technique can lower this frequency significantly. The number needed...... to treat is three for preventing a complication requiring reinsertion. Infection rates are low for both types of ventriculostomies. Accordingly, we recommend use of Bolt-connected EVDs in neurosurgical practice....
Qu Jiadi; Dou Yikang; Zhu Shiming
It expounds that the key of solving thermal transient sealing problem is to obtain the thermal increment of stud-bolt loading. This loading, as a primary stress loading, is directly related to the bolt fatigue life and transient loading spectrum for vessel analysis. The fundamental works and main results of ultrasonic measurement on RPV stud-bolt loading on Qinshan site are also presented. The measuring capability has exceeded 1 m in length and temperature of 280 degree C, therefore, it is possible to be used in the field of NPP. The paper is the continuation of research work for sealing analysis and tests on the RPV (see SMiRT-9, 10)
Bies, Christian M.; Alaerts, Louis; Bonitz, Frank W.; Devlin, Russell S.; Minogue, Patrick
This article presents the MIDAS VI testing robot used by Westinghouse / WesDyne. This is a remotely operated underwater vehicle which positions ultrasonic probes under camera control. This vehicle makes it possible to substantially reduce the time required for setting up and preparing ultrasonic tests on core baffle former bolts. It has also accelerated the test procedure itself. Test methods have also been developed for bolt types which were hitherto considered incapable of being tested. One of these methods is based on a phased array probe. The article also reports on experiences gained over the course of years in testing core baffle former bolts in European nuclear power plants using the SUPREEM testing robot.
Ra, S W; Im, K H; Woo, Y D; Lee, S G; Kim, H J; Song, S J; Kim, S K; Cho, Y T; Jung, J A
All Various defects could be generated in bolts for a use of oil filters for the manufacturing process and then may affect to the safety and quality in bolts. Also, fine defects may be imbedded in oil filter system during multiple forging manufacturing processes. So it is very important that such defects be investigated and screened during the multiple manufacturing processes. Therefore, in order effectively to evaluate the fine defects, the design parameters for bobbin-types were selected under a finite element method (FEM) simulations and Eddy current testing (ECT). Especially the FEM simulations were performed to make characterization in the crack detection of the bolts and the parameters such as number of turns of the coil, the coil size and applied frequency were calculated based on the simulation results. (paper)
Burgess, T.W.; Walton, G.R.; Meighan, T.G.; Paul, B.L.
Special tooling has been developed and used to tighten toroidal field (TF) coil casing bolts that have loosened from years of Tokamak Fusion Test Reactor (TFTR) operation. Due to their location, many of the TF casing bolts cannot be directly accessed or viewed; their condition was first discovered during unrelated inspections in 1988. Engineering solutions were, sought until 1992, when a remotely operated wrench concept was successfully demonstrated on a TF coil mockup. The concept was developed into several working tools that have successfully been applied to tighten several thousand TF casing bolts during recent scheduled outages. This effort has improved the integrity and reliability of the TF coil system in preparing for the final experimental phase of the TFTR. This paper discusses the design and application of this tooling
Chen, Jinzhong; He, Renyang; Kang, Xiaowei; Yang, Xuyun
The non-destructive testing of small-sized (M12-M20) stainless steel bolts in servicing is always a technical problem. This article focuses on the simulation and experimental research of stainless steel bolts with an artificial defect reflector using ultrasonic phased array inspection. Based on the observation of the sound field distribution of stainless steel bolts in ultrasonic phased array as well as simulation modelling and analysis of the phased array probes' detection effects with various defect sizes, different artificial defect reflectors of M16 stainless steel bolts are machined in reference to the simulation results. Next, those bolts are tested using a 10-wafer phased array probe with 5 MHz. The test results finally prove that ultrasonic phased array can detect 1-mm cracks in diameter with different depths of M16 stainless steel bolts and a metal loss of Φ1 mm of through-hole bolts, which provides technical support for future non-destructive testing of stainless steel bolts in servicing.
Tingaev, A. K.; Gubaydulin, R. G.; Shaburova, N. A.
The causes of the failure of a high-tensile stud 2M48-6gx500 10.9 made from steel grade 30HGSA which led to a temporary inoperability of a tower crane were investigated. The bolts were used to assemble the tower sections and collapsed after 45 days from the moment the crane was commissioned. The cracks in the fracture are identified as fatigue with the characteristic sites of nucleation, sustainable development and static dolomite. To determine the possible causes of stud bolts destruction, metallographic, durometric and mechanical tests were carried out from which it follows that the stud bolt material in its original state corresponded to the delivery conditions. The destruction of the stud bolt appears to have resulted from a combination of several unfavorable factors: uncertainty about the actual tension of the stud bolt due to the lack of information about the magnitude of the twist factor; partial displacement of the centers of the brackets holes and rotation of the stud bolt axis during the sections’ assembly; no tight contact on the support surfaces of the section brackets. All this led to a discrepancy between the actual design of the stud bolt, the appearance of additional forces and the destruction of the stud bolt.
Hamed S. Askar
An experimental investigation with the objective of retrofitting flat slabs damaged due to punching shear using prestressed vertical bolts is presented in this paper. The parameters examined in this study are vertical prestressed bolts with different ratios within the slab thickness, slab thickness and central column size. Through the experimental tests the load carrying capacity, deformation characteristics and the cracking behavior have been investigated. A comparison between the behavior of retrofitted slabs and their references showed that the proposed system of repair is effective and could be used in practice. A comparison between the experimental results and calculated punching failure load based on the formulas adopted by different codes, showed a reasonable agreement.
Bednarski, Ł.; Sieńko, R.; Howiacki, T.
This article presents the possibility of using structural health monitoring system data for the analysis of structure’s operation during its life cycle. Within the specific case study it was proved, that continuous, automatic and long term monitoring of selected physical quantities such as strains and temperatures, can significantly improve the assessment of technical condition by identifying hazardous phenomena. In this work the analysis of structural behaviour of post-tensioned girders within the roofing of sport halls in Cracow, Poland, was performed based on measurement results and verified by numerical model carried out in SOFiSTiK software. Thanks to the possibility of performing calculations in real time and informing the manager of the object about abnormalities it is possible to manage the structure in effective way by, inter alia, planning the renovations or supporting decisions about snow removal.
Hu, Yong; Cui, W.; Pedersen, Preben Terndrup
The prupose of this paper is to propose a methodology to assess the time-variant ultimate strength of ship hull girder under the degradations of corrosion and fatigue. The effects of fatigue cracks on the tensile and compressive residual ultimate strength of stiffened panels and unstiffened plates...... are analyzed by an FE method. Based on FE analysis restuls, some empirical formulae are provided for effective calculation of the compressive or tensile ultimate strength of cracked or intact unstiffened plates or stiffened panels. A non-linear corrosion model is used to determine the corrosion rate of plates......, webs and flanges, respectively. The effects of inspections and repair are taken into account. A minimum net thickness rule is used to determine repair policies. A procedure is proposed to determine the maximum allowable corrosion thickness of different parts of the hull cross section. The procedure...
Kim, Eui Soo; Kim, Jong Hyuk
Recently, as a means of resolving the issue of legal liability in the event of an accident or a disaster, a wide variety of simulation techniques, such as structural and structure-fluid interaction analysis, have been used in the field of forensic engineering. The plate girder bridge discussed in this paper was being constructed between a pier and an abutment to expand an existing bridge, but an accident whereby the bridge overturned occurred at the end of the concrete laying process for a protective wall. This accident was caused by additional loads not being considered at the time of the design as well as the actual construction being different from the design. The additional loads ultimately generated a negative support force. In this study, we determined the cause of the accident by comparing the structural stability of the original design with that of the additional, non-conforming construction using MIDAS structural analysis
Lin, Xiankun; Zhang, Lingmi; Guo, Qintao; Zhang, Yufeng
The dynamic finite element model (FEM) of a prestressed concrete continuous box-girder bridge, called the Tongyang Canal Bridge, is built and updated based on the results of ambient vibration testing (AVT) using a real-coded accelerating genetic algorithm (RAGA). The objective functions are defined based on natural frequency and modal assurance criterion (MAC) metrics to evaluate the updated FEM. Two objective functions are defined to fully account for the relative errors and standard deviations of the natural frequencies and MAC between the AVT results and the updated FEM predictions. The dynamically updated FEM of the bridge can better represent its structural dynamics and serve as a baseline in long-term health monitoring, condition assessment and damage identification over the service life of the bridge.
Full Text Available The fatigue damage assessment of bridge components by conducting a full scale fatigue testing is often prohibitive. A need, therefore, exists to estimate the fatigue damage in bridge components by a simulation of bridge-vehicle interaction dynamics due to the action of the actual traffic. In the present paper, a systematic method has been outlined to find the fatigue damage in the continuous bridge girder based on stress range frequency histogram and fatigue strength parameters of the bridge materials. Vehicle induced time history of maximum flexural stresses has been obtained by Monte Carlo simulation process and utilized to develop the stress range frequency histogram taking into consideration of the annual traffic volume. The linear damage accumulation theory is then applied to calculate cumulative damage index and fatigue life of the bridge. Effect of the bridge span, pavement condition, increase of vehicle operating speed, weight and suspension characteristics on fatigue life of the bridge have been examined.
Full Text Available In this paper, full scale load test of a horizontally curved steel box-girder bridge is carried out in order to detect structural defects, which reportedly result in unwanted vibrations in nearby buildings. The bridge is tested under the passage of six heavy vehicles at different speeds, so as to determine its static and dynamic responses. A total number of one hundred and two (102 sensors are used to measure the displacements, strains, and accelerations of different points of the bridge. It is observed that the bridge vibrates at a fundamental frequency of 2.6 Hz intensively and the first mode of vibration is torsional instead of flexural. The dominant frequency of vibration of the nearby buildings is computed to be approximately 2.5Hz using rational formulas. Thus, nearness of the fundamental frequency of the bridge to those of the adjacent buildings may be causing resonance phenomenon. However, in static load tests, low ranges of strain and displacement illustrated adequate structural capacity and appropriate safety under static loads. Numerical models are created using ANSYS and SAP2000 software products, so as to design the loading test and calibrate the finite element models. The connections of the transversal elements to the girders, transversal element spacing, and changes of the stiffness values of the slabs were found to be the most influential issues in the finite elements calibration process. Finally, considering the total damage of all members, the final health score of the bridge was evaluated as 89% indicating that the bridge is in a very good situation.
... provided in the desired format, reporting burden (time and financial resources) is minimized, collection... Extension of Existing Information Collection; Safety Standards for Roof Bolts in Metal and Nonmetal Mines... agencies with an opportunity to comment on proposed and continuing collections of information in accordance...
Jovašević, S.; Correia, J. A F O; Pavlovic, M.; Rebelo, C.; De Jesus, A. M P; Veljkovic, M.; Simoes da Silva, L
A steel hybrid structural solution for onshore wind turbine towers was proposed in the European project SHOWTIME. This solution is used in the lattice structure for the lower portion of the tower. Recently, a procedure for fatigue life estimation of steel half-pipes bolted connections applied in
Full Text Available Within the research project “FR-TI4/329 Research and development - creating an application system for the design and analysis of soil and rock anchors including the development of monitoring elements”, an extensive stage of field load tests of rock bolts was carried out. The tests were conducted at 14 locations with varied rock composition. Before the initial tests, a loading stand was designed and constructed. A total of 201 pieces of tensile tests of bolts having lengths from 0.5 up to 2.5 m, a diameter of 22-32 mm, were performed. These were fully threaded rods, self-drilling rods, and fiberglass rods. The bolts were clamped into the cement and resin. The loading tests were always performed until material failure of bolts or shear stress failure at the interface cement-rock. At each location, basic geotechnical survey was carried out in the form of core drilling in a length of 3.0 metres with the assessment of the rock mass in situ, and laboratory testing of rock mechanics. Upon the completion of testing protocols, rock mass properties analysis was performed focusing on the evaluation of shear friction at the grouting-rock interface.
He, Zhong-qun; Wang, Jun
Temperature sensitive periods and growth characteristics of endive under different temperatures were investigated in greenhouse by weekly reciprocal transferring experiment condition between warm (17 °C) and cold (average 10.5 °C) environment. The results indicated that difference in growth rate of endive was significant in cold and warm environments. There was no temperature sensitive period in endive, and it could feel outside temperature, thus, conducted vernalization induction in setting temperature range (2-17 °C). Meanwhile, low temperature favored the flower bud differentiation. Endives all completed flower bud differentiation and bloting either in warm or in cold environment. It took 24 days to complete flower bud differentiation in cold environment and 60 days in warm environment, and bolting was 7 days later in warm environment than in cold environment. From seeding to bolting, it took 111 days in warm environment and 104 days in cold environment, respectively. After flowering induction, the seeding bolting rate from warm environment to cold environment was obviously higher than that from cold to warm environment and higher temperature led to faster bolting in this period.
Pedersen, Martin Bo Uhre; Clorius, Christian Odin; Damkilde, Lars
deviation of 37 kN. Comparing this mean residual strength with previously recorded test data reveals a 5% strength reduction. The force displacement curves shows no plastic capacity in the connections. At fracture, a displacement between 0.4 mm and 1.0 mm was observed. In the majority of failures the bolts...
Shaffer, T.F.; Revie, R.W.; Mandal, A.
Stainless steel and nickel alloy Swellex rock bolts have been developed to provide long-term ground support in corrosive environments or in underground openings that are inaccessible for periodic reconditioning. Laboratory and underground testing has shown that the mechanical properties of stainless steel Swellex rock bolts am adequate for long term service. The corrosivity of underground sites may vary considerably and no one grade of stainless steel will provide adequate corrosion resistance economically for permanent service at all sites. Six stainless steels and two nickel alloys have been evaluated and used to manufacture Swellex. These alloys can be used to manufacture all types of rock bolts including mechanically anchored bolts. The selection of the lowest-cost corrosion-resistant alloy suitable for the lifetime objective at a given site may be problematic. Therefore, a mine corrosivity assessment procedure, in which the performance of several candidate materials for permanent service at a specific site can be determined quickly and economically, is being developed and will be available in 1995
Schwirian, R.E.; Forsyth, D.R.; Snyder, M.D.; Bhandari, D.R.; Barsic, J.A.; Rabenstein, W.D.
In Westinghouse pressurized water reactors (PWR) the reactor core is surrounded by baffle plates, which provide lateral restraint for the fuel assemblies at the core boundary. Baffle plates are attached to horizontal supports called former plates by baffle-former bolts. The formers are attached to the core barrel which also provides vertical support for the core. The B3 analysis program addresses the possibility of reduced baffle-former bolting in Westinghouse U.S. domestic plant designs with respect to the relevant design criteria. Since safety is the overriding motivation for the program, faulted events have received the most in-depth attention. This focus has been reinforced by the fact that the loads produced by the loss-of-coolant-accident (LOCA) have usually been the most limiting of all those considered. Consequently, much of the presentation below deals with the development of analysis techniques and acceptance criteria to demonstrate that LOCA-induced loads on the bolts and the fuel assemblies will be acceptable with significantly reduced baffle-former bolting. A discussion of the other faulted, normal, and upset analyses performed as part of the program will also be presented. (author)
Vourlias, Kostas; Seroglou, Fanny
Could Usain Bolt achieve what teachers often fail to do? Could this famous Olympic winner challenge and motivate students to study mechanics and introduce them to the principles of physics in a fun way, outside of the classroom? In order to answer these questions, we "invited" for one semester the world record holder to visit our Greek…
Lemaire, E.; Couet, D.; Molinie, D.; Grandjean, Y.; Radat, M.P.; Guttmann, D.
Failure analysis and mechanical testing indicate that control rod drive mechanisms malfunctioning by 1995-96 is due to rupture by fatigue of a bolt inside the stationary gripper assembly. Fatigue is enhanced by free working following surface adaptation and unscrewing of the assembly. These results are taken into account for the choice of a new anti-rotation device. (authors)
Full Text Available Concrete multicell box-girder bridges are a common choice among the designers for various ranges of bridges. In order to provide safer and greater speed of traffic, the roadway is built as straight as possible. The use of skewed bridges has increased considerably in the recent years for roadway. The skewed bridges have quite different mechanical behavior from the straight bridges, although for skew angles less than 20 degrees, it is reasonably safe to ignore the effect of skew angles and analyze that at the straight bridge. In this study, in developing an analytical solution, an extensive parametric study was carried out to determine the maximum positive and negative stress distribution factors and to calculate the maximum distribution factor of deflection along the mid-span of skewed multicell box-girder bridges. A total of 240 representative bridges numerical models were selected and analyzed using SAP2000 finite element software. It was found that the span length, number of boxes, number of lanes and skew angles significantly affected the distribution factors of stress and deflection. Finally, several equations were proposed for stress and deflection distribution factors of multicell box-girder bridges for the application of American Association of State Highway and Transportation officials load and resistance factor design live loads.
Full Text Available Piezoceramic based active sensing methods have been researched to monitor preload on bolt connections. However, there is a saturation problem involved with this type of method. The transmitted energy is sometimes saturated before the maximum preload which is due to it coming into contact with flat surfaces. When it comes to flat contact surfaces, the true contact area will easily saturate with the preload. The design of a new type of bolt looseness monitoring sensor, a smart washer, is to mitigate the saturation problem. The smart washer is composed of two annular disks with contact surfaces that are machined into convex and concave respectively, to eliminate the complete flat contact surfaces and to reduce the saturation effect. One piezoelectric patch is bonded on the non-contact surface of each annular disk. These two mating annular disks form a smart washer. One of the two piezoelectric patches serves as an actuator to generate an ultrasonic wave that propagates through the contact surface; the other one serves as a sensor to detect the propagated waves. The wave energy propagated through the contact surface is proportional to the true contact area which is determined by the bolt preload. The time reversal method is used to extract the peak of the focused signal as the index of the transmission wave energy; then, the relationship between the signal peak and bolt preload is obtained. Experimental results show that the focused signal peak value changes with the bolt preload and presents an approximate linear relationship when the saturation problem is experienced. The proposed smart washer can monitor the full range of the rated preload.
Jensen, Find M.; Branner, K.; Nielsen, Per H. (and others)
This report presents the setup and result of a full-scale test of a reinforced glass fibre/epoxy box girder used in 34m wind turbine blade. The tests were performed at the Blaest test facility in August 2006. The test is an important part of a research project established in cooperation between Risoe DTU, the National Laboratory for Sustainable Energy at the Technical University of Denmark -, SSP-Technology A/S and Blaest (Blade test centre A/S) and it has been performed as a part of Find Moelholt Jensen's PhD study. This report contains the complete test data for the final test, in which the box girder was loaded until failure. A comprehensive description of the test setup is given. This report deals only with tests and results. There are no conclusions on the data in this report, but references are given to publications, where the data are used and compared with FEM etc. Various kinds of measuring equipment have been used during these tests: acoustic emission, 330 strain gauges, 24 mechanical displacement devices and two optical deformation measuring systems. The mechanical displacement devices measured both global (absolute) and local (relative) deflection and the optical systems measured surface deformation. A prediction was made on the location of the failure of the girder. At this location the majority of the measuring equipment was concentrated. The prediction was proved to be correct and valuable information of the behaviour of the box girder prior to failure was obtained. The experimental investigation consisted of the following load configurations: -Flapwise bending -Torsion Ultrasonic scanning of the box girder was performed before, during and after the test the box girder. This was done to investigate whether the girder was damaged by the load or imperfection (productions defects) growth. (au)
Sørensen, Karsten Engsig
Afhandlingen analysere de konkurrenceretlige og selskabsretlige regler som er bestemmende for hvordan et joint venture samarbejde er struktureret......Afhandlingen analysere de konkurrenceretlige og selskabsretlige regler som er bestemmende for hvordan et joint venture samarbejde er struktureret...
Abid, M.; Alam, K.
Pipe joints flanged or welded are commonly used in industry for different applications ranging from sewerage to the high pressure and temperature applications. However, with the rapidly changing technological trends, for optimized space such as for heat exchanger applications, pipe joint design needs special consideration, especially for the internal pipe where no flanged/bolted joint due to space constraint can be used. In addition, where joint opening/closing is the requirement for maintenance or other functional purposes, it becomes inevitable to use some special design. In this paper, a push joint proposed is designed, analyzed, optimized and tested for safe stress and operating conditions. An experimental test rig is designed and tests are performed for internal pressure and temperature separately and joint's behaviour is analyzed in detail for any leaks. FEA results are compared and verified with the mathematical results. Based on the experimental observations, the joint is safe as no leaks are observed. (author)
Ames, Nicoli M.; Lauffer, James P.; Jew, Michael D.; Segalman, Daniel Joseph; Gregory, Danny Lynn; Starr, Michael James; Resor, Brian Ray
The problem of understanding and modeling the complicated physics underlying the action and response of the interfaces in typical structures under dynamic loading conditions has occupied researchers for many decades. This handbook presents an integrated approach to the goal of dynamic modeling of typical jointed structures, beginning with a mathematical assessment of experimental or simulation data, development of constitutive models to account for load histories to deformation, establishment of kinematic models coupling to the continuum models, and application of finite element analysis leading to dynamic structural simulation. In addition, formulations are discussed to mitigate the very short simulation time steps that appear to be required in numerical simulation for problems such as this. This handbook satisfies the commitment to DOE that Sandia will develop the technical content and write a Joints Handbook. The content will include: (1) Methods for characterizing the nonlinear stiffness and energy dissipation for typical joints used in mechanical systems and components. (2) The methodology will include practical guidance on experiments, and reduced order models that can be used to characterize joint behavior. (3) Examples for typical bolted and screw joints will be provided.
Parunov, Josko; Guedes Soares, C.
This paper aims at quantifying the changes in notional reliability levels that result from redesigning an existing Aframax tanker to comply with the Common Structural Rules (CSR) for double-hull oil tankers. The probability of structural failure is calculated using the first-order reliability method. The evaluation of the wave-induced load effects that occur during long-term operation of the ship in the seaway is carried out in accordance with the International Association of Classification Societies (IACS)-recommended procedure, while transfer functions are calculated using the sink-source 3D linear method. The still-water loads are defined on the basis of a statistical analysis of loading conditions from the loading manual. The ultimate collapse bending moment of the midship cross section, which is used as the basis for the reliability formulation, is evaluated by progressive collapse analysis and by a single-step procedure according to CSR. The reliability assessment is performed for 'as-built' and 'corroded' states of the existing ship and a reinforced ship complying with CSR. It is shown that the hull-girder failure probability of an Aframax tanker is reduced several times due to the reinforcements according to CSR. Sensitivity analysis and a parametric study are performed to investigate the variability of results with the change of parameters of pertinent random variables within their plausible ranges. Finally, differences between load combination approaches by Ferry-Borges and Castanheta method and Turkstra's rule are investigated
Full Text Available Purpose. The article analyzes the railway load LM71 for the purpose of its application in national design projects of the railway girder bridges. Purpose of the article is harmonization of national design codes of enginnering structures with the European standards (Eurocodes. Methodology. Analytical calculation methods (influence lines, the matrix analysis and computer programming are used in the article. Findings. Deflected mode parameters of the railway bridges under the influence of loads C14 and LM71 have certain differences. The extent of these differences depends on length, material of drift structures and also on dynamic coefficients. These dependences should be considered in national design codes and in harmonized with Eurocodes standards. In the further researches relationships between load C14 and models SW, HSLM taking into account various dynamic effects and trains speedis planned to determine. Originality. The presented results, in particular deflected mode parameters (including loads with dynamic coefficients, obtained for the first time. Practical value. Results of research are used in National Annex to the National Standard of Ukraine NSTU-N B EN 1991-2:2010. Eurocode 1. Actions on structures. Part 2. Traffic loads on bridges (EN 1991-2:2003.
Full Text Available Based on the basic theory of wavelet neural networks and finite element model updating method, a basic framework of damage prognosis method is proposed in this paper. Firstly, a damaged I-steel beam model testing is used to verify the feasibility and effectiveness of the proposed damage prognosis method. The results show that the predicted results of the damage prognosis method and the measured results are very well consistent, and the maximum error is less than 5%. Furthermore, Xinyihe Bridge in the Beijing-Shanghai Highway is selected as the engineering background, and the damage prognosis is conducted based on the data from the structural health monitoring system. The results show that the traffic volume will increase and seasonal differences will decrease in the next year and a half. The displacement has a slight increase and seasonal characters in the critical section of mid span, but the strain will increase distinctly. The analysis results indicate that the proposed method can be applied to the damage prognosis of girder bridge structures and has the potential for the bridge health monitoring and safety prognosis.
Full Text Available This study aims to undertake a statistical study to evaluate the accuracy of nine models that have been previously proposed for estimating the ultimate resistance of plate girders subjected to patch loading. For each model, mean errors and standard errors, as well as the probability of underestimating or overestimating patch load resistance, are estimated and the resultant values are compared one to another. Prior to that, the models are initially calibrated in order to improve interaction formulae using an experimental data set collected from the literature. The models are then analyzed by computing design factors associated with a target risk level (probability of exceedance. These models are compared one to another considering uncertainties existed in material and geometrical properties. The Monte Carlo simulation method is used to generate random variables. The statistical parameters of the calibrated models are calculated for various coefficients of variations regardless of their correlation with the random resistance variables. These probabilistic results are very useful for evaluating the stochastic sensitivity of the calibrated models.
Alberto Maria Avossa
Full Text Available The paper deals with the proposal and application of a procedure for the seismic retrofit of an existing multispan prestressed concrete girder bridge defined explicitly for the use of friction pendulum devices as an isolation system placed between piers top and deck. First, the outcomes of the seismic risk assessment of the existing bridge, performed using an incremental noniterative Nonlinear Static Procedure, based on the Capacity Spectrum Method as well as the Inelastic Demand Response Spectra, are described and discussed. Then, a specific multilevel design process, based on a proper application of the hierarchy of strength considerations and the Direct Displacement-Based Design approach, is adopted to dimension the FPD devices. Furthermore, to assess the impact of the FPD nonlinear behaviour on the bridge seismic response, a device model that reproduces the variation of the normal force and friction coefficient, the bidirectional coupling, and the large deformation effects during nonlinear dynamic analyses was used. Finally, the paper examines the effects of the FPD modelling parameters on the behaviour of the retrofitted bridge and assesses its seismic response with the results pointing out the efficiency of the adopted seismic retrofit solution.
Chen, G. W.; Omenzetter, P.
This paper presents the implementation of an updating procedure for the finite element model (FEM) of a prestressed concrete continuous box-girder highway off-ramp bridge. Ambient vibration testing was conducted to excite the bridge, assisted by linear chirp sweepings induced by two small electrodynamic shakes deployed to enhance the excitation levels, since the bridge was closed to traffic. The data-driven stochastic subspace identification method was executed to recover the modal properties from measurement data. An initial FEM was developed and correlation between the experimental modal results and their analytical counterparts was studied. Modelling of the pier and abutment bearings was carefully adjusted to reflect the real operational conditions of the bridge. The subproblem approximation method was subsequently utilized to automatically update the FEM. For this purpose, the influences of bearing stiffness, and mass density and Young's modulus of materials were examined as uncertain parameters using sensitivity analysis. The updating objective function was defined based on a summation of squared values of relative errors of natural frequencies between the FEM and experimentation. All the identified modes were used as the target responses with the purpose of putting more constrains for the optimization process and decreasing the number of potentially feasible combinations for parameter changes. The updated FEM of the bridge was able to produce sufficient improvements in natural frequencies in most modes of interest, and can serve for a more precise dynamic response prediction or future investigation of the bridge health.
Madsen, C. A.; Kragh-Poulsen, J.-C.; Thage, K. J.; Andreassen, M. J.
The monopile foundation is the dominant solution for support of wind turbines in offshore wind farms. It is normally grouted to the transition piece which connects the foundation to the turbine. Currently, the bolted steel ring flange connection is investigated as an alternative. The monopile--transition piece connection has specific problems, such as out-of-verticality and installation damage from driving the MP into the seabed and it is not fully known how to design for these. This paper presents the status of the ongoing development work and an estimate of what still needs to be covered in order to use the connection in practice. This involves presentation of an analytical and non-linear FE analysis procedure for the monopile-transition piece connection composed of two L flanges connected with preloaded bolts. The connection is verified for ultimate and fatigue limit states based on an integrated load simulation carried out by the turbine manufacturer.
Tinl, N.; Menzemer, C. C.; Manigandan, K.; Srivatsan, T. S.
In this paper, the bearing capacity, taken as a combination of strength, elongation, and failure by fracture characteristics of bolt holes in two aluminum alloys, 5052-H32 and 6061-T6, that were deformed in uniaxial tension is presented and discussed. The specific role played by bolt hole confinement on the bearing capacity of each aluminum alloy is highlighted. An increase in the bearing ratio caused plastic deformation around the holes to gradually increase. For both the chosen aluminum alloys the average bearing ratio at the time of failure of the test sample was found to vary with end distance. The experimentally determined strength was observably larger than the calculated bearing strength obtained using guaranteed minimum mechanical properties and recommended mathematical relationships. The nature of final fracture of each aluminum alloy is carefully examined and the intrinsic features present on the fracture surface are rationalized in concurrence with macroscopic mechanical response.
Pircher, Rebecca; Geisenberger, Dorothee; Große Perdekamp, Markus; Neukamm, Merja; Pollak, Stefan; Schmidt, Ulrike; Thierauf-Emberger, Annette
In humans, most fatalities from slaughterer's guns are suicides committed by persons familiar with stunning devices. The great majority of cases accounts for shots to the head, especially the frontal region. Only a small number of two subsequent cranial shots from captive-bolt humane killers have been reported up to now. In the case presented by the authors, a suicide by simultaneous shots to the head fired from two different makes of captive-bolt guns (one of them having two separate outlets for the combustion gases in the muzzle plane, the other type having no additional openings) is described for the first time. One of the shooting devices remained in firm contact with the left hand and produced patterned staining from rust corresponding to the surface relief of the gun. The medicolegal and criminalistic aspects of this unique case are discussed with reference to the pertinent literature.
The objective of this investigation was to establish the allowable design loads (tension, shear, and combined load) for expansion bolts to be installed in regular 4000 psi mix concrete, Magnetite 5000 psi mix concrete, and Steel Shot 5000 psi mix concrete at the Fast Flux Test Facility. The test loads included Static Loads and Alternating Loads which simulate the dynamic loads of vibratory equipment and dynamic earthquake loads.
Skrzypkowski, Krzysztof; Korzeniowski, Waldemar; Zagórski, Krzysztof; Dudek, Piotr
In the underground mines of the Legnica-Głogów Copper District (LGOM) the main way to protect the room excavation is the use of a rock bolt support. For many years, it has proven to be an efficient security measure in excavations which met all safety standards and requirements. The article presents the consumption of the rock bolt support in the Mining Department "Polkowice-Sieroszowice" in the years 2010-2015 as well as the number of bolt supports that were used to secure the excavations. In addition, it shows the percentage of bolt supports that were used to conduct rebuilding work and cover the surface of exposed roofs. One of the factors contributing to the loss of the functionality of bolt supports is corrosion whose occurrence may lead directly to a reduction in the diameter of rock bolt support parts, in particular rods, bearing plates and nuts. The phenomenon of the corrosion of the bolt support and its elements in underground mining is an extremely common phenomenon due to the favorable conditions for its development in mines, namely high temperature and humidity, as well as the presence of highly aggressive water. This involves primarily a decrease in the capacity of bolt support construction, which entails the need for its strengthening, and often the need to perform the reconstruction of the excavation. The article presents an alternative for steel bearing plates, namely plates made using the spatial 3D printing technology. Prototype bearing plates were printed on a 3D printer Formiga P100 using the "Precymit" material. The used printing technology was SLS (Selective Laser Sintering), which is one of the most widely used technologies among all the methods of 3D printing for the short series production of the technical parts of the final product. The article presents the stress-strain characteristic of the long expansion connected rock bolt support OB25 with a length of 3.65 m. A rock bolt support longer than 2.6 m is an additional bolt support in
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Chen, B.; Ghezelbash, A.M.; Kamali, V.; Setare, M.R.
We show that there exists a holographic 2D CFT description of a Kerr-Bolt-AdS-dS spacetime. We first consider the wave equation of a massless scalar field propagating in extremal Kerr-Bolt-AdS-dS spacetimes and find in the 'near region', the wave equation in extremal limit could be written in terms of the SL(2,R) quadratic Casimir. This suggests that there exist dual CFT descriptions of these black holes. In the probe limit, we compute the scattering amplitudes of the scalar off the extremal black holes and find perfect agreement with the CFT prediction. Furthermore we study the holographic description of the generic four-dimensional non-extremal Kerr-Bolt-AdS-dS black holes. We find that if focusing on the near-horizon region, for the massless scalar scattering in the low-frequency limit, the radial equation could still be rewritten as the SL(2,R) quadratic Casimir, suggesting the existence of dual 2D description. We read the temperatures of the dual CFT from the conformal coordinates and obtain the central charges by studying the near-horizon geometry of near-extremal black holes. We recover the macroscopic entropy from the microscopic counting. We also show that for the super-radiant scattering, the retarded Green's functions and the corresponding absorption cross sections are in perfect match with CFT prediction.
Chen, B., E-mail: email@example.com [Department of Physics, and State Key Laboratory of Nuclear Physics and Technology, and Center for High Energy Physics, Peking University, Beijing 100871 (China); Ghezelbash, A.M., E-mail: firstname.lastname@example.org [Department of Physics and Engineering Physics, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5E2 (Canada); Kamali, V., E-mail: email@example.com [Department of Campus of Bijar, Kurdistan University, Bijar (Iran, Islamic Republic of); Setare, M.R., E-mail: firstname.lastname@example.org [Department of Campus of Bijar, Kurdistan University, Bijar (Iran, Islamic Republic of)
We show that there exists a holographic 2D CFT description of a Kerr-Bolt-AdS-dS spacetime. We first consider the wave equation of a massless scalar field propagating in extremal Kerr-Bolt-AdS-dS spacetimes and find in the 'near region', the wave equation in extremal limit could be written in terms of the SL(2,R) quadratic Casimir. This suggests that there exist dual CFT descriptions of these black holes. In the probe limit, we compute the scattering amplitudes of the scalar off the extremal black holes and find perfect agreement with the CFT prediction. Furthermore we study the holographic description of the generic four-dimensional non-extremal Kerr-Bolt-AdS-dS black holes. We find that if focusing on the near-horizon region, for the massless scalar scattering in the low-frequency limit, the radial equation could still be rewritten as the SL(2,R) quadratic Casimir, suggesting the existence of dual 2D description. We read the temperatures of the dual CFT from the conformal coordinates and obtain the central charges by studying the near-horizon geometry of near-extremal black holes. We recover the macroscopic entropy from the microscopic counting. We also show that for the super-radiant scattering, the retarded Green's functions and the corresponding absorption cross sections are in perfect match with CFT prediction.
Scott A Sinex
Full Text Available A simple activity is described which is appropriate for any class dealing with measurement. It introduces students to the important scientific process of mathematical modeling and online collaboration. Students, working in groups, determine the mass of a bolt indirectly by extrapolation from massing the bolt with one to five nuts on it and determining the equation of the line; the y-intercept being the mass of the bolt. Students gain experience with using a balance, graphing data, and analyzing results using algebraic skills. They calculate percent error after measuring the bolt’s mass directly and can compare this with the error limits from the least squares fit. Groups enter data into a web-based form and the data is examined by the class using Google Docs in a collaborative manner. After entering data in Google Docs, the students use an interactive Excel spreadsheet to compare their results to the best-fit line obtained by linear regression (pre-built into the spreadsheet for novices. In the spreadsheet, they further explore the model to gain an understanding and examine the influence of scatter (error in the data and material density.
Soo, Vi Kie; Compston, Paul; Doolan, Matthew
Stricter vehicle emission legislation has led to the increasing use of lightweight materials and multi-material concepts to reduce the vehicle mass. To account for the complexity of multi-material vehicle designs, the choice of joining techniques used is becoming more diverse. Moreover, the different material combinations, and their respective joining methods play an important role in determining the potential of full material separation in a closed-loop system. This paper evaluates the types of joining technologies used in the automotive industry, and identifies those that hinder the sorting of ELV materials. The study is based on an industrial shredding trial of car doors. Observations from the case study showed that steel screws and bolts are increasingly used to combine different material types and are less likely to be perfectly liberated during the shredding process. The characteristics of joints that lead to impurities and valuable material losses, such as joint strength, material type, size, diameter, location, and protrusion level, can influence the material liberation in the current sorting practices and thus, lead to ELV waste minimisation. Additionally, the liberation of joints is also affected by the density and thickness of materials being joined. Correlation analyses are carried out to further support the influence of mechanical screws and bolts on material separation efficiencies. The observations are representative of the initial phases of current global ELV sorting practices. Copyright © 2017 Elsevier Ltd. All rights reserved.
Domínguez Mayans, Félix
This thesis aims to study the structural consequences of the damages produced by vehicle impact in a pres-stressed concrete bridge girder and the repair procedure in a real case-study damaged after the bridge was opened to service. From the analysis of the situation of the beam and its damage state, a study of the repair actions carried out on this beam has been analyzed in order to determine the efficiency of the repair and if other alternatives are possible or more efficient. A stat...
Liu, Xueying; Lv, Shanshan; Liu, Ran; Fan, Shuangxi; Liu, Chaojie; Liu, Renyi; Han, Yingyan
A cool temperature is preferred for lettuce cultivation, as high temperatures cause premature bolting. Accordingly, exploring the mechanism of bolting and preventing premature bolting is important for agriculture. To explore this relationship in depth, morphological, physiological, and transcriptomic analyses of the bolting-sensitive line S39 at the five-leaf stage grown at 37°C were performed in the present study. Based on paraffin section results, we observed that S39 began bolting on the seventh day at 37°C. During bolting in the heat-treated plants, GA3 and GA4 levels in leaves and the indoleacetic acid (IAA) level in the stem reached a maximum on the sixth day, and these high contents were maintained. Additionally, bolting begins in the fifth day after GA3 treatment in S39 plants, GA3 and GA4 increased and then decreased, reaching a maximum on the fourth day in leaves. Similarly, IAA contents reached a maximum in the stem on the fifth day. No bolting was observed in the control group grown at 25°C, and significant changes were not observed in GA3 and GA4 levels in the controls during the observation period. RNA-sequencing data implicated transcription factors (TFs) in regulating bolting in lettuce, suggesting that the high GA contents in the leaves and IAA in the stem promote bolting. TFs possibly modulate the expression of related genes, such as those encoding hormones, potentially regulating bolting in lettuce. Compared to the control group, 258 TFs were identified in the stem of the treatment group, among which 98 and 156 were differentially up- and down-regulated, respectively; in leaves, 202 and 115 TFs were differentially up- and down-regulated, respectively. Significant changes in the treated group were observed for C2H2 zinc finger, AP2-EREBP, and WRKY families, indicating that these TFs may play important roles in regulating bolting.
Westesson, P.L.; Hatala, M.; Tallents, R.H.; Katzberg, R.W.; Musgrave, M.; Levitt, S.
This paper determines the frequency of MR signs of abnormal temporomandibular joints (TMJs) in asymptomatic volunteers. Forty-two volunteers with 84 clinically normal TMJs were imaged in the sagittal and coronal planes with surface coil MR imaging. Sagittal closed and open and coronal closed views were obtained bilaterally in all volunteers. The images were classified as normal (superior disk position) or abnormal (disk displacement of degenerative joint disease). Eighteen joints in 11 volunteers were abnormal; 12 had disk displacement with reduction and six had disk displacement without reduction, with associated degenerative joint disease in three of the six. Asymptomatic internal derangement and degenerative joint disease occur in about one-fourth of asymptomatic volunteers
... wrist joints can all be replaced (Figure 1). Artificial joints in the hand may help: Reduce joint pain Restore or maintain joint motion Improve the look and alignment of the joint(s) Improve overall hand function Causes In a normal joint, bones have a smooth surface made of a substance ...
Liu, Sixin; Wang, Fei; Fu, Lei; Meng, Xu; Lei, Linlin; Weng, Changnian; Jiao, Pengfei
The accurate inspection of the duct condition in post-tensioned prestressed concrete (PPC) is an essential part of GPR concrete inspection. The purpose is to inspect the grouting condition of the ducts where the strands are located, to find out if there is a void in the ducts, and if any water exists. In order to investigate the radar image characteristics of different PPC duct defects, a number of model girders were manufactured. Three major ducts are included in our study: (1) well grouted and no void (normal condition); (2) the duct is half filled, and the void is filled by water or air; and (3) the duct is not filled at all, and the duct is water or air filled. The data corresponding to seven different situations are acquired and processed. It is found that the radar can detect the first interface in the duct, and the detailed structure inside the duct cannot be ‘seen’ from the images directly. Characteristic curves greatly help the interpretation. A completely void duct is the easiest to differentiate from the others. The signature for this situation is characterized by a strong and clear reflection interface which becomes weaker as the void is water filled. The normal condition shows the weakest reflection interface. As for the half void situation, the front scan shows a similar result to the normal condition whether it is water or air filled, and the back scan shows similar features to the completely void situation. The experiment and analysis is helpful and instructive for practical engineering inspection. (paper)
Liu, Sixin; Weng, Changnian; Jiao, Pengfei; Wang, Fei; Fu, Lei; Meng, Xu; Lei, Linlin
The accurate inspection of the duct condition in post-tensioned prestressed concrete (PPC) is an essential part of GPR concrete inspection. The purpose is to inspect the grouting condition of the ducts where the strands are located, to find out if there is a void in the ducts, and if any water exists. In order to investigate the radar image characteristics of different PPC duct defects, a number of model girders were manufactured. Three major ducts are included in our study: (1) well grouted and no void (normal condition); (2) the duct is half filled, and the void is filled by water or air; and (3) the duct is not filled at all, and the duct is water or air filled. The data corresponding to seven different situations are acquired and processed. It is found that the radar can detect the first interface in the duct, and the detailed structure inside the duct cannot be ‘seen’ from the images directly. Characteristic curves greatly help the interpretation. A completely void duct is the easiest to differentiate from the others. The signature for this situation is characterized by a strong and clear reflection interface which becomes weaker as the void is water filled. The normal condition shows the weakest reflection interface. As for the half void situation, the front scan shows a similar result to the normal condition whether it is water or air filled, and the back scan shows similar features to the completely void situation. The experiment and analysis is helpful and instructive for practical engineering inspection.
Hye Sun Cho
Full Text Available Late bolting after cold exposure is an economically important characteristic of radish (Raphanus sativus L., an important Brassicaceae root vegetable crop. However, little information is available regarding the genes and pathways that govern flowering time in this species. We performed high-throughput RNA sequencing analysis to elucidate the molecular mechanisms that determine the differences in flowering times between two radish lines, NH-JS1 (late bolting and NH-JS2 (early bolting. In total, 71,188 unigenes were identified by reference-guided assembly, of which 309, 788, and 980 genes were differentially expressed between the two inbred lines after 0, 15, and 35 days of vernalization, respectively. Among these genes, 218 homologs of Arabidopsis flowering-time (Ft genes were identified in the radish, and 49 of these genes were differentially expressed between the two radish lines in the presence or absence of vernalization treatment. Most of the Ft genes up-regulated in NH-JS1 vs NH-JS2 were repressors of flowering, such as RsFLC, consistent with the late-bolting phenotype of NH-JS1. Although the functions of genes down-regulated in NH-JS1 were less consistent with late-bolting characteristics than the up-regulated Ft genes, several Ft enhancer genes, including RsSOC1, a key floral integrator, showed an appropriate expression to the late-bolting phenotype. In addition, the patterns of gene expression related to the vernalization pathway closely corresponded with the different bolting times of the two inbred lines. These results suggest that the vernalization pathway is conserved between radish and Arabidopsis.
Full Text Available Integral abutment bridges are becoming rather common, due to the durability problems of bearings and expansion joints. At the same time, among short- and medium-span bridges, multi-beam steel-concrete composite deck with hot-rolled girder is an economical and interesting alternative to traditional pre-stressed concrete solutions. The two concepts can be linked together to design integral steel-concrete composite bridges with the benefits of two typologies. The most critical aspect for these bridges is usually the joints between deck and piers or abutments. In this paper, an innovative beam-to-pier joint is proposed and a theoretical and experimental study is introduced and discussed. The analyzed connection is aimed at combining general ease of construction with a highly simplified assembly procedure and a good transmission of hogging and sagging moment at the supports in continuous beams. For this purpose, the traditional shear studs, used at the interface between steel beam and upper concrete slab, are also used at the ends of steel profiles welded horizontally to the end plates. To better understand the behaviour of this kind of joints and the roles played by different components, three large-scale specimens were tested and an FE model was implemented. The theoretical and experimental results confirmed the potential of the proposed connection for practical applications and indicated the way to improve its structural behaviour.
Full Text Available Structural health monitoring (SHM has attracted much attention in recent years, which enables early warnings of structural failure, condition assessments, and rational maintenance/repair strategies. In the context of bridges, many long-span steel bridges in China have been installed with the SHM systems; however, the applications of the SHM in prestressed concrete (PSC bridges are still rather limited. On the other hand, the PSC box girder bridges are extensively used in highway and railway systems and premature damage of these bridges is often reported, resulting in considerable maintenance and/or replacement costs. First, this paper presents a state-of-art review on the SHM of long-span PSC bridges. Monitoring strategies, methods, and previous applications for these bridges are summarized and discussed. In order to well capture the behavior of the bridge during its whole life and to maximize the use of sensors, a life-cycle monitoring strategy is proposed, in which the sensor layout is determined according to requirements for construction monitoring, completion test, and in-service monitoring. A case study is made on a three-span PSC box girder bridge in China. The system configuration, sensor layout, and data communications, and so forth, are presented. The up-to-date monitored structural responses are analyzed and compared with the design values.
Full Text Available This is a case study in which the partial collapse of a prestressed concrete box-girder bridge in Brazil happened only nine days after removing the supporting scaffolding. It is believed that the actual reinforcement longitudinal steel bars in the pile caps were underestimated. Although only part of the structure had collapsed, it was decided that the whole structure should be demolished. It was claimed that there was not available alternatives for ‘in situ’ structural recovery that would not compromise local traffic and safety precaution procedures. This paper presents an alternative technique for the bridge structural recovery. The application of this technique was possible because the prestressing process used unbonded pos-tensioned concrete, i.e. the sheaths were not filled with grout. The technique was based on the use of a weld torch to cut the tensioned strands in the box-girders methodically, unloading the pillars and foundations. Experimental tests were performed ‘in loco’ and proved to be effective and safe. The application of this suggested technique ‘in situ’ is believed to be an original contribution to the knowledge.
Full Text Available To systematically study the vehicle–bridge coupled dynamic response and its change rule with different parameters, a vehicle model with seven degrees of freedom was built and the total potential energy of vehicle space vibration system was deduced. Considering the stimulation of road roughness, the dynamic response equation of vehicle–bridge coupled system was established in accordance with the elastic system principle of total potential energy with stationary value and the “set-in-right-position” rule. On the basis of the self-compiled Fortran program and bridge engineering, the dynamic response of long-span continuous girder bridge under vehicle load was studied. This study also included the calculation of vehicle impact coefficient, evaluation of vibration comfort, and analysis of dynamic response parameters. Results show the impact coefficient changes with lane number and is larger than the value calculated by the “general code for design of highway bridges and culverts (China”. The Dieckmann index of bridge vibration is also related to lane number, and the vibration comfort evaluation is good in normal conditions. The relevant conclusions from parametric analyses have practical significance to dynamic design and daily operation of long-span continuous girder bridges in expressways. Safety and comfort are expected to improve significantly with further control of the vibration of vehicle–bridge system.
Tuan Minh Ha
Full Text Available Structural responses have been used as inputs in the evaluation procedures of civil structures for years. Apart from the degradation of a structure itself, changes in the environmental conditions affect its characteristics. For adequate maintenance, it is necessary to quantify the environment-induced changes and discriminate them from the effects due to damage. This study investigates the variation in the vibration responses of prestressed concrete (PC girders, which were deteriorated because of the alkali–silica reaction (ASR, concerning ambient temperature and humidity. Three PC girders were exposed to outdoor weather conditions outside the laboratory, one of which had a selected amount of fly ash in its mixture to mitigate the ASR. The girders were periodically vibration tested for one and a half years. It was found that when the temperature and humidity increased, the frequencies and damping ratios decreased in proportion. No apparent variation in the mode shapes could be identified. A finite element model was proposed for numerical verification, the results of which were in good agreement with the measured changes in the natural frequencies. Moreover, the different dynamic performances of the three specimens indicated that the fly ash significantly affected the vibrations of the PC girders under ASR deterioration.
Full Text Available Lettuce (Lactuca sativa L. is one of the most important leafy vegetable that is consumed during its vegetative growth. The transition from vegetative to reproductive growth is induced by high temperature, which has significant economic effect on lettuce production. However, the progression of floral transition and the molecular regulation of bolting are largely unknown. Here we morphologically characterized the inflorescence development and functionally analyzed the FLOWERING LOCUS T (LsFT gene during bolting regulation in lettuce. We described the eight developmental stages during floral transition process. The expression of LsFT was negatively correlated with bolting in different lettuce varieties, and was promoted by heat treatment. Overexpression of LsFT could recover the late-flowering phenotype of ft-2 mutant. Knockdown of LsFT by RNA interference dramatically delayed bolting in lettuce, and failed to respond to high temperature. Therefore, this study dissects the process of inflorescence development and characterizes the role of LsFT in bolting regulation in lettuce.
Chen, Zijing; Han, Yingyan; Ning, Kang; Ding, Yunyu; Zhao, Wensheng; Yan, Shuangshuang; Luo, Chen; Jiang, Xiaotang; Ge, Danfeng; Liu, Renyi; Wang, Qian; Zhang, Xiaolan
Lettuce (Lactuca sativa L.) is one of the most important leafy vegetable that is consumed during its vegetative growth. The transition from vegetative to reproductive growth is induced by high temperature, which has significant economic effect on lettuce production. However, the progression of floral transition and the molecular regulation of bolting are largely unknown. Here we morphologically characterized the inflorescence development and functionally analyzed the FLOWERING LOCUS T (LsFT) gene during bolting regulation in lettuce. We described the eight developmental stages during floral transition process. The expression of LsFT was negatively correlated with bolting in different lettuce varieties, and was promoted by heat treatment. Overexpression of LsFT could recover the late-flowering phenotype of ft-2 mutant. Knockdown of LsFT by RNA interference dramatically delayed bolting in lettuce, and failed to respond to high temperature. Therefore, this study dissects the process of inflorescence development and characterizes the role of LsFT in bolting regulation in lettuce. PMID:29403510
... or conditions. It may be linked to arthritis , bursitis , and muscle pain . No matter what causes it, ... Autoimmune diseases such as rheumatoid arthritis and lupus Bursitis Chondromalacia patellae Crystals in the joint: Gout (especially ...
Design of joints in steel and composite structures Eurocode 3 : design of steel structures : part 1-8 : design of joints, Eurocode 4 : design of composite steel and concrete structures : part 1-1 : general rules and rules for buildings
This book details the basic concepts and the design rules included in Eurocode 3 Design of steel structures Part 1-8 Design of joints. Joints in composite construction are also addressed through references to Eurocode 4 Design of composite steel and concrete structures Part 1-1 General rules and rules for buildings. Attention has to be duly paid to the joints when designing a steel or composite structure, in terms of the global safety of the construction, and also in terms of the overall cost, including fabrication, transportation and erection. Therefore, in this book, the design of the joints themselves is widely detailed, and aspects of selection of joint configuration and integration of the joints into the analysis and the design process of the whole construction are also fully covered. Connections using mechanical fasteners, welded connections, simple joints, moment-resisting joints and lattice girder joints are considered. Various joint configurations are treated, including beam-to-column, beam-to-beam, ...
Underhill, P. R.; Uemura, C.; Krause, T. W.
Fatigue cracks are prone to develop around fasteners found in multi-layer aluminum structures on aging aircraft. Bolt hole eddy current (BHEC) is used for detection of cracks from within bolt holes after fastener removal. In support of qualification towards a target a90/95 (detect 90% of cracks of depth a, 95% of the time) of 0.76 mm (0.030"), a preliminary probability of detection (POD) study was performed to identify those parameters whose variation may keep a bolt hole inspection from attaining its goal. Parameters that were examined included variability in lift-off due to probe type, out-of-round holes, holes with diameters too large to permit surface-contact of the probe and mechanical damage to the holes, including burrs. The study examined the POD for BHEC of corner cracks in unfinished fastener holes extracted from service material. 68 EDM notches were introduced into two specimens of a horizontal stabilizer from a CC-130 Hercules aircraft. The fastener holes were inspected in the unfinished state, simulating potential inspection conditions, by 7 certified inspectors using a manual BHEC setup with an impedance plane display and also with one inspection conducted utilizing a BHEC automated C-Scan apparatus. While the standard detection limit of 1.27 mm (0.050") was achieved, given the a90/95 of 0.97 mm (0.039"), the target 0.76 mm (0.030") was not achieved. The work highlighted a number of areas where there was insufficient information to complete the qualification. Consequently, a number of recommendations were made. These included; development of a specification for minimum probe requirements; criteria for condition of the hole to be inspected, including out-of-roundness and presence of corrosion pits; statement of range of hole sizes; inspection frequency and data display for analysis.
Zarzalejos, José María, E-mail: email@example.com [External at F4E, c/Josep Pla, n.2, Torres Diagonal Litoral, Edificio B3, E-08019, Barcelona (Spain); Fernández, Elena; Caixas, Joan; Bayón, Angel [F4E, c/Josep Pla, n.2, Torres Diagonal Litoral, Edificio B3, E-08019, Barcelona (Spain); Polo, Joaquín [Iberdrola Ingeniería y Construcción, Avenida de Manoteras 20, 28050 Madrid (Spain); Guirao, Julio [Numerical Analysis Technologies, S L., Marqués de San Esteban 52, Entlo, 33209 Gijon (Spain); García Cid, Javier [Iberdrola Ingeniería y Construcción, Avenida de Manoteras 20, 28050 Madrid (Spain); Rodríguez, Eduardo [Mechanical Engineering Department EPSIG, University of Oviedo, Gijon (Spain)
Highlights: • The ITER Vacuum Vessel Bolted Ribs assemblies are modelled using Finite Elements. • Finite Element submodelling techniques are used. • Stress results are obtained for all the assemblies and a post-processing is performed. • All the elements of the assemblies are compliant with the regulatory provisions. • Submodelling is a time-efficient solution to verify the structural integrity of this type of structures. - Abstract: The ITER Vacuum Vessel (VV) primary function is to enclose the plasmas produced by the ITER Tokamak. Since it acts as the first radiological barrier of the plasma, it is classified as a class 2 welded box structure, according to RCC-MR 2007. The VV is made of an inner and an outer D-shape, 60 mm-thick double shell connected through thick massive bars (housings) and toroidal and poloidal structural stiffening ribs. In order to provide neutronic shielding to the ex-vessel components, the space between shells is filled with borated steel plates, called In-Wall Shielding (IWS) blocks, and water. In general, these blocks are connected to the IWS ribs which are connected to adjacent housings. The development of a Finite Element model of the ITER VV including all its components in detail is unaffordable from the computational point of view due to the large number of degrees of freedom it would require. This limitation can be overcome by using submodelling techniques to simulate the behaviour of the bolted ribs assemblies. Submodelling is a Finite Element technique which allows getting more accurate results in a given region of a coarse model by generating an independent, finer model of the region under study. In this paper, the methodology and several simulations of the VV bolted ribs assemblies using submodelling techniques are presented. A stress assessment has been performed for the elements involved in the assembly considering possible types of failure and including stress classification and categorization techniques to analyse
Jensen, Aage; Poulsen, Ervin
The second generation of CFRP laminate has recently been developed. It is a multi directional CFRP laminate, i.e. a laminate with carbon fibres having several directions other than the first generation. The paper describes the laboratory tests carried out in order to develop anchorage devices...... for such multi directional CFRP laminates which are epoxy-bonded and bolted or nailed to the concrete substrate for the purpose of strengthening against failure caused by bending. The tests were carried out at the Technical University of Denmark, IABM and Byg-DTU...
The Nuts and Bolts of Proof instructs students on the basic logic of mathematical proofs, showing how and why proofs of mathematical statements work. It provides them with techniques they can use to gain an inside view of the subject, reach other results, remember results more easily, or rederive them if the results are forgotten.A flow chart graphically demonstrates the basic steps in the construction of any proof and numerous examples illustrate the method and detail necessary to prove various kinds of theorems.* The "List of Symbols" has been extended.* Set Theory section has been strengthened with more examples and exercises.* Addition of "A Collection of Proofs"
Jorge Munaiar Neto
Full Text Available This paper presents three-dimensional numerical models of bolted connections of cold-formed steel members. The purpose of three-dimensional numerical models is to evaluate the strength and the behavior of these connections. The computer code ANSYS v. 6.0, based on Finite Element Method, was used to analyze the numerical models response. In order to evaluate the efficiency and reliability of the constructed models, the numerical results were compared with experimental results obtained from experimental assays carried out in Structures Laboratory of EESC/USP. In this sense, the numerical results presented satisfactory agreement when compared with experimental results.
Madsen, C.A.; Kragh-Poulsen, Jens-Christian; Tage, K.J.
The monopile foundation is the dominant solution for support of wind turbines in offshore wind farms. It is normally grouted to the transition piece which connects the foundation to the turbine. Currently, the bolted steel ring flange connection is investigated as an alternative. The monopile......--transition piece connection has specific problems, such as out-of-verticality and installation damage from driving the MP into the seabed and it is not fully known how to design for these. This paper presents the status of the ongoing development work and an estimate of what still needs to be covered in order...
Currás Móstoles, María Rosa
Esta tesis doctoral se centra en el estudio del tratamiento de los referentes culturales en A Man for All Seasons, de Robert Bolt. Partiendo del hecho de que los textos literarios son productos de la cultura que los alojan, una obra literaria manifiesta su adscripción a dicha cultura por medio de ciertos elementos conocidos como referentes culturales. La importancia de los elementos culturales en traducción viene reforzada por la consideración de que los estudios de traducción actualmen...
Zhang, Xun; Li, Xiaozhen; Hao, Hong; Wang, Dangxiong; Li, Yadong
A side effect of high-speed railway and urban rail transit systems is the associated vibration and noise. Since the use of concrete viaducts is predominant in railway construction due to scarce land resources, low-frequency (20-200 Hz) structure-radiated noise from concrete bridges is a principal concern. Although it is the most commonly used bridge type, the mechanism of noise emission from box-shaped bridge girders when subjected to impact forces from moving trains, which sounds like beating a drum, has not been well studied. In this study, a field measurement was first made on a simply-supported box-shaped bridge to record the acceleration of the slabs and the associated sound pressures induced by running trains. These data indicated that a significant beat-wave noise occurred in the box-shaped cavity when the train speed was around 340 km/h, which arose from the interference between two sound waves of 75.0 Hz and 78.8 Hz. The noise leakage from the bridge expansion joint was serious and resulted in obvious noise pollution near the bridge once the beat-wave noise was generated in the cavity. The dominant frequency of the interior noise at 75.0 Hz was confirmed from the spectrum of the data and the modal analysis results, and originated from the peak vibration of the top slab due to resonance and the first-order vertical acoustic mode, which led to cavity resonance, amplifying the corresponding noise. The three-dimensional acoustic modes and local vibration modes of the slab were calculated by using the finite element method. A simplified vehicle-track-bridge coupling vibration model was then developed to calculate the wheel-rail interaction force in a frequency range of 20-200 Hz. Numerical simulations using the boundary element method confirmed the cavity resonance effect and the numerical results agreed well with the data. Based on the calibrated numerical model, three noise reduction measures, i.e., adding a horizontal baffle in the interior cavity, narrowing
Full Text Available Column-tree moment resisting frames, as the efficient shop-welded and field-bolted structural systems, are used in many countries. Very limited research has been carried out on such systems under fire conditions. This paper presents experimental investigations of the behavior of beam and bolted splice connections in steel column-tree moment resisting frames exposed to fire. Two full-scale steel sub-frames with different splice connections were tested under ISO 834 standard fire. The flange splice plates were configured as a single plate with single shear bolts in first specimen, and as double plates with double shear bolts in second specimen. The observation of thermal and structural fire behaviors including temperature histories, temperature-deflection of the beam, temperature-rotation of splice connections and failure modes were investigated. The temperature-deflection and temperature-rotation curves remained in the elastic range until about 600°C. Beyond 600°C, the behavior would be highly nonlinear plastic. The beam splice connection failed due to shear fracture of top bolts at temperatures beyond 750°C. Consequently, stub beam web failed at those temperatures because of block-shear. Using double plates with double shear bolts for flange splices would enhance the temperature resistance and rotational capacity of the beam splice connections. Both tests results confirmed that specimens retain the capacity to support the design load when the average beam temperature does not exceed 600°C. This temperature limit confirms the temperature criteria provided by ASTM E119 and ANSI/UL 263 for a restrained beam, and can be used to specify the minimum fire resistance criteria for beams in column-tree MRFs. The measured time-deflection curves showed that the restrained fire resistance rating for both unprotected specimens obtained about 15 minutes in both tests.
Kim, Ji Hun; Hwang, Sun Kwang; Im, Yong-Taek; Son, Il-Heon; Bae, Chul Min
Highlights: ► Fine-grained AA6061-O was produced by a continuous hybrid process. ► It consists of rolling, ECAP, and drawing. ► High-strength bolt was manufactured with the fine-grained AA6061-O. ► The UTS and micro-hardness of the bolt was increased by 50%. ► The route C was better in making a uniform micro-hardness distribution in the bolt. - Abstract: It is well known that the development of a continuous manufacturing process to apply severe plastic deformation (SPD) is a major challenge for industrial usages to improve the mechanical properties of the material through grain refinement. In this study, fine-grained AA6061-O wire was manufactured by a two-pass hybrid process consisting of drawing, equal channel angular pressing and rolling in a continuous manner to investigate the effects of processing routes for two different routes, A and C, on the variation of ultimate tensile strength (UTS) and micro-hardness distribution. The UTS value (185 MPa) of the specimen processed by the two-pass hybrid process with route A was higher than that of 171 MPa obtained from the two-pass wire-drawing process and was equivalent to the level of 184 MPa processed by the three-pass wire-drawing process. The average micro-hardness value (Hv 58.0) obtained from the two-pass hybrid process through route C was the highest among all the cases. According to transmission electron microscopy, the original grain was subdivided and elongated owing to deformation during the processes. The specimen processed by the two-pass hybrid process through route C showed smaller deformation bands and had potentially higher angle grain boundaries compared to the specimen processed by the two-pass wire-drawing process. Finally, the high-strength bolt was manufactured using the fine-grained AA6061-O wire prepared by the continuous hybrid process to check its formability. A ductile fracture at the first thread right above the jaw was observed in the bolt tension test of the manufactured bolt
Full Text Available According to the shared intentionality hypothesis proposed by Michael Tomasello, two cognitive upgrades – joint and collective intentionality, respectively – make human thinking unique. Joint intentionality, in particular, is a mindset supposed to account for our early, species-specific capacity to participate in collaborative activities involving two (or a few agents. In order to elucidate such activities and their proximate cognitive-motivational mechanism, Tomasello draws on philosophical accounts of shared intentionality. I argue that his deference to such cognitively demanding accounts of shared intentional activities is problematic if his theoretical ambition is in part to show that and how early (prelinguistic and precultural capacities for joint action contribute to the development of higher cognitive capacities.
Nan, Guo; Yao, JunEn
A real-time inspection of the key components is necessary for ensuring safe operation of freight car. While traditional inspection depends on the trained human inspectors, which is time-consuming and lower efficient. With the development of machine vision, vision-based inspection methods get more railway on-spot applications. The cross rod end fastening bolts are important components on both sides of the train body that fixing locking plates together with the freight car main structure. In our experiment, we get the images containing fastening bolt components, and accurately locate the locking plate position using a linear Support Vector Machine (SVM) locating model trained with Histograms of Oriented Gradients (HOG) features. Then we extract the straight line segment using the Line Segment Detector (LSD) and encoding them in a range, which constitute a straight line segment dataset. Lastly we determine the locking plate's working state by the linear pattern. The experiment result shows that the localization accurate rate is over 99%, the fault detection rate is over 95%, and the module implementation time is 2f/s. The overall performance can completely meet the practical railway safety assurance application.
Liang, Naiguo; Cheng, Dayou; Liu, Qiaohong; Cui, Jie; Luo, Chengfei
Sugar beet (Beta vulgaris) is a biennial crop that accounts for 30% sugar production of the world. Vernalization is an essential factor for sugar beet reproductative growth under long days. Although genes association with bolting and flowering were well explored, the difference of proteomics in the two growth stages were still poorly understood. To address the molecular mechanism at the level of proteins, an isobaric tags for relative and absolute quantification (iTRAQ)-based quantitative proteomics approach was employed to the three different growth stages (germination, bolting, flowering) of vernalized samples and the corresponding stage germination (17W weeks), 19W and 20W of nonvernalized samples. A total of 1110 peptides, 842 unique peptides and 570 proteins were identified. Most of them were assigned to phenylpropanoid biosynthesis, hormone metabolism and protein processing pathway. IAA and Gibberellins (GA3) promoted growth and development in a threshold manner at growth stage germination after vernalization. A novel discovery was that IAA biosynthetic pathway of sugar beet was the Trp-dependent. In addition, two predominant pathways of protein processing association with vernalization were also identified in sugar beet at growth stage flowering. This study provided an in-depth understanding of the molecular mechanism of vernalization at the level of proteomics. Copyright © 2017 The Authors. Published by Elsevier Masson SAS.. All rights reserved.
Stevens, Kenneth N.
Under the mentoring of Dick Bolt, and the stimulation he provided in the Acoustics Laboratory at MIT, many students were exposed to a range of topics in acoustics, including mechanisms of sound generation, radiation, and propagation, noise control, acoustics of resonators and rooms, human responses to sound, and speech perception under various adverse conditions. As someone who became interested in speech communication, I have recognized that this kind of quantitative background in acoustics is an important requirement for developing models of how humans produce speech, how they perceive and understand speech, and how children acquire these skills. Speech production involves sound sources produced by a nonlinear mechanical system and by noise arising from turbulent airflow. Sound is propagated in a vocal tract with yielding walls, and acoustic coupling is introduced by lossy resonators attached to the vocal tract, including the trachea and the nasal cavity. These acoustic principles of sound generation create an inventory of sound types that give rise to distinctive responses in the ears and brains of listeners. The solid grounding in acoustics provided by Dick Bolt and his leadership have helped in the formation of this linkage between acoustics, speech physiology, linguistics, and human perception.
Steiner, Lisa J; Burgess-Limerick, Robin; Eiter, Brianna; Porter, William; Matty, Tim
Operators of roof bolting machines in underground coal mines do so in confined spaces and in very close proximity to the moving equipment. Errors in the operation of these machines can have serious consequences, and the design of the equipment interface has a critical role in reducing the probability of such errors. An experiment was conducted to explore coding and directional compatibility on actual roof bolting equipment and to determine the feasibility of a visual feedback system to alert operators of critical movements and to also alert other workers in close proximity to the equipment to the pending movement of the machine. The quantitative results of the study confirmed the potential for both selection errors and direction errors to be made, particularly during training. Subjective data confirmed a potential benefit of providing visual feedback of the intended operations and movements of the equipment. This research may influence the design of these and other similar control systems to provide evidence for the use of warning systems to improve operator situational awareness. Published by Elsevier Ltd.
Steiner, Lisa; Burgess-Limerick, Robin; Porter, William
The authors examine the pattern of direction errors made during the manipulation of a physical simulation of an underground coal mine bolting machine to assess the directional control-response compatibility relationships associated with the device and to compare these results to data obtained from a virtual simulation of a generic device. Directional errors during the manual control of underground coal roof bolting equipment are associated with serious injuries. Directional control-response relationships have previously been examined using a virtual simulation of a generic device; however, the applicability of these results to a specific physical device may be questioned. Forty-eight participants randomly assigned to different directional control-response relationships manipulated horizontal or vertical control levers to move a simulated bolter arm in three directions (elevation, slew, and sump) as well as to cause a light to become illuminated and raise or lower a stabilizing jack. Directional errors were recorded during the completion of 240 trials by each participant Directional error rates are increased when the control and response are in opposite directions or if the direction of the control and response are perpendicular.The pattern of direction error rates was consistent with experiments obtained from a generic device in a virtual environment. Error rates are increased by incompatible directional control-response relationships. Ensuring that the design of equipment controls maintains compatible directional control-response relationships has potential to reduce the errors made in high-risk situations, such as underground coal mining.
Michael, Robert; Yantek, David; Johnson, David; Ferro, Ernie; Swope, Chad
Among underground coal miners, hearing loss remains one of the most common occupational illnesses. In response to this problem, the National Institute for Occupational Safety and Health (NIOSH) Office of Mine Safety and Health Research (OMSHR) conducts research to reduce the noise emission of underground coal-mining equipment, an example of which is a roof bolting machine. Field studies show that, on average, drilling noise is the most significant contributor to a roof bolting machine operator's noise exposure. NIOSH OMSHR has determined that the drill steel and chuck are the dominant sources of drilling noise. NIOSH OMSHR, Corry Rubber Corporation, and Kennametal, Inc. have developed a bit isolator that breaks the steel-to-steel link between the drill bit and drill steel and a chuck isolator that breaks the mechanical connection between the drill steel and the chuck, thus reducing the noise radiated by the drill steel and chuck, and the noise exposure of the roof bolter operator. This paper documents the evolution of the bit isolator and chuck isolator including various alternative designs which may enhance performance. Laboratory testing confirms that production bit and chuck isolators reduce the A-weighted sound level generated during drilling by 3.7 to 6.6 dB. Finally, this paper summarizes results of a finite element analysis used to explore the key parameters of the drill bit isolator and chuck isolator to understand the impact these parameters have on noise.
Full Text Available Corrosion costs money”, The Columbus battle institute estimates that corrosion costs Americans more than $ 220 billion annually, about 4.3% of the gross natural product .Now a days due to increase of pollution, the rate of corrosion is also increasing day-by-day mainly in India, so, to save the steel structures, galvanizing is the best and the simplest solution. Due to this reason galvanizing industries are increasing day-by-day since mid of 1700s.Galvanizing is a controlled metallurgical combination of zinc and steel that can provide a corrosion resistance in a wide variety of environment. In fact, the galvanized metal corrosion resistance factor can be some 70 to 80 times greater that the base metal material. Keeping in mind the importance of this industry, a noble approach of process automation in galvanized nut-bolt manufacturing plant is presented here as nuts and bolts are the prime ingredient of any structure. In this paper the main objectives of any industry like survival, profit maximization, profit satisfying and sales growth are fulfilled. Furthermore the environmental aspects i.e. pollution control and energy saving are also considered in this paper. The whole automation process is done using programmable logic controller (PLC which has number of unique advantages like being faster, reliable, requires less maintenance and reprogrammable. The whole system has been designed and tested using GE, FANUC PLC.
Tränkner, Conny; Lemnian, Ioana M; Emrani, Nazgol; Pfeiffer, Nina; Tiwari, Surya P; Kopisch-Obuch, Friedrich J; Vogt, Sebastian H; Müller, Andreas E; Schilhabel, Markus; Jung, Christian; Grosse, Ivo
Sugar beet ( Beta vulgaris ssp. vulgaris) is a biennial, sucrose-storing plant, which is mainly cultivated as a spring crop and harvested in the vegetative stage before winter. For increasing beet yield, over-winter cultivation would be advantageous. However, bolting is induced after winter and drastically reduces yield. Thus, post-winter bolting control is essential for winter beet cultivation. To identify genetic factors controlling bolting after winter, a F 2 population was previously developed by crossing the sugar beet accessions BETA 1773 with reduced bolting tendency and 93161P with complete bolting after winter. For a mapping-by-sequencing analysis, pools of 26 bolting-resistant and 297 bolting F 2 plants were used. Thereby, a single continuous homozygous region of 103 kb was co-localized to the previously published BR 1 QTL for post-winter bolting resistance (Pfeiffer et al., 2014). The BR 1 locus was narrowed down to 11 candidate genes from which a homolog of the Arabidopsis CLEAVAGE AND POLYADENYLATION SPECIFICITY FACTOR 73-I ( CPSF73-I ) was identified as the most promising candidate. A 2 bp deletion within the BETA 1773 allele of BvCPSF73-Ia results in a truncated protein. However, the null allele of BvCPSF73-Ia might partially be compensated by a second BvCPSF73-Ib gene. This gene is located 954 bp upstream of BvCPSF73-Ia and could be responsible for the incomplete penetrance of the post-winter bolting resistance allele of BETA 1773. This result is an important milestone for breeding winter beets with complete bolting resistance after winter.
Tränkner, Conny; Lemnian, Ioana M.; Emrani, Nazgol; Pfeiffer, Nina; Tiwari, Surya P.; Kopisch-Obuch, Friedrich J.; Vogt, Sebastian H.; Müller, Andreas E.; Schilhabel, Markus; Jung, Christian; Grosse, Ivo
Sugar beet (Beta vulgaris ssp. vulgaris) is a biennial, sucrose-storing plant, which is mainly cultivated as a spring crop and harvested in the vegetative stage before winter. For increasing beet yield, over-winter cultivation would be advantageous. However, bolting is induced after winter and drastically reduces yield. Thus, post-winter bolting control is essential for winter beet cultivation. To identify genetic factors controlling bolting after winter, a F2 population was previously developed by crossing the sugar beet accessions BETA 1773 with reduced bolting tendency and 93161P with complete bolting after winter. For a mapping-by-sequencing analysis, pools of 26 bolting-resistant and 297 bolting F2 plants were used. Thereby, a single continuous homozygous region of 103 kb was co-localized to the previously published BR1 QTL for post-winter bolting resistance (Pfeiffer et al., 2014). The BR1 locus was narrowed down to 11 candidate genes from which a homolog of the Arabidopsis CLEAVAGE AND POLYADENYLATION SPECIFICITY FACTOR 73-I (CPSF73-I) was identified as the most promising candidate. A 2 bp deletion within the BETA 1773 allele of BvCPSF73-Ia results in a truncated protein. However, the null allele of BvCPSF73-Ia might partially be compensated by a second BvCPSF73-Ib gene. This gene is located 954 bp upstream of BvCPSF73-Ia and could be responsible for the incomplete penetrance of the post-winter bolting resistance allele of BETA 1773. This result is an important milestone for breeding winter beets with complete bolting resistance after winter. PMID:27895650
Joint imaging is a proven diagnostic procedure which has become indispensable to the detection and treatment of different joint diseases in almost all disciplines. The method is suited for early diagnosis of joint affections both in soft tissue and bone which cannot be detected by X-ray or other procedures. The local activity accumulation depends on the rate of metabolism and is visualized in the scan, which in turn enables the extension and floridity of focal lesions to be evaluated and followed-up. Although joint scans may often give hints to probabilities relevant to differential diagnosis, the method is non-specific and only useful if based on the underlying clinical picture and X-ray finding, if possible. The radiation exposure is very low and does not represent a hazard in cases of adequate assessment of indication. In pregnant women and children the assessment of indication has to be based on very strict principles. The method is suited for out-patient diagnosis and can be applied in all installations equipped with a gamma camera and a technetium generator. (orig.) [de
Pristed Nielsen, Helene
of anti-discrimination in Europe today? And what empirical evidence may be found for such a joint approach? The paper discusses how the contemporary EU context differs from the American context which prompted Crenshaw to raise the point about intersectionality, and it analyses documents and interviews...
As baby boomers age and home care grows in popularity as an alternative to institutionalized care, opportunities abound for entrepreneurs to meet the demand through professional private-duty businesses. This article examines the nuts and bolts of launching and operating a successful private-duty agency.
Oliveira, Steffan Edward Octávio; Gregory, Neville George; Dalla Costa, Filipe Antonio; Gibson, Troy John; Paranhos da Costa, Mateus José Rodrigues
The efficiency of stunning cattle was assessed in 443 animals (304 pure Zebu and 139 crossbred cattle), being mainly mature bulls and cows. Cattle were stunned using a Jarvis pneumatically powered penetrating captive bolt gun operating with low (160-175psi, N=82) and high (190psi, N=363) airline pressure, which was within the manufactures specifications. Signs of brain function and the position of the shots on the heads were recorded after stunning. Velocity of the captive bolt and its physical parameters were calculated. Cattle shot with low pressures showed more rhythmic respiration (27 vs. 8%, P<0.001), less tongue protrusion (4 vs. 12%, P=0.03) and less masseter relaxation (22 vs. 48%, P<0.001). There was an increased frequency of shots in the ideal position when cattle were shot with the low compared to high airline pressures (15.3 vs. 3.1%). Bolt velocity and its physical parameters were significantly (P<0.01) higher when using high pressure. Airline pressures below 190psi are inappropriate when shooting adult Zebu beef cattle with pneumatically powered penetrating captive bolt guns. Copyright © 2017 Elsevier Ltd. All rights reserved.
Pijpers, R.J.M.; Kolstein, M.H.
An effective application of Very High Strength Steel (VHSS) in civil engineering structures is expected in stiff, truss like structures, typically made of Circular Hollow Sections (CHS). Use of castings in combination with CHS could be promising for the design of highly fatigue resistant joints.
Chang, Kuo Tsi
This paper suggests a parallel resistor to reduce DC time constant and DC response time of the transient response, induced immediately after an AC voltage connected to a bolt-clamped Langevin transducer (BLT) is switched off. An equivalent circuit is first expressed. Then, an open-circuit transient response at the terminals induced by initial states is derived and measured, and thus parameters for losses of the BLT device are estimated by DC and AC time constants of the transient response. Moreover, a driving and measuring system is designed to determine transient response and steady-state responses of the BLT device, and a parallel resistor is connected to the BLT device to reduce the DC time constant. Experimental results indicate that the DC time constant greatly exceeds the AC time constant without the parallel resistor, and greatly decreases from 42 to 1 ms by a 100-kOmega parallel resistor.
Hoche, Holger; Oechsner, Matthias
Delayed brittle fractures of high-strength bolts of the strength class 10.9 are presented, taking the example of three damage cases. The respective damage mechanisms could be attributed to hydrogen induced stress corrosion which was caused, in turn, by hydrogen absorption during operation. The examples were chosen with a particular focus on the material condition's susceptibility which explains the cause for the occurrence of the damage mechanism. However, in only one of the three cases the susceptibility was evident and could be explained by violations of normative specifications and an unfavorable material choice. Whereas in the two other examples, only slight or no deviations from the standards and/or regulations could be found. The influencing parameters that caused the damage, those that further promoted the damage, as well as possible corrective actions are discussed taking into account the three exemplary damage cases.
Full Text Available Abstract The circular hollow sections (CHS are being widely employed in steel structures around the world, increasing the development of new researches. This article proposes an innovative connection model for circular hollow sections that facilitates and reduces the assembly cost of hollow section structures. The proposed connection is a tube sleeve, used to splice two tubes, composed of an inner tube with a diameter smaller than the connecting tubes, which is connected to the outer tubes by bolts passing through both tubes. This connection can be a cheaper and easier alternative to flange connections, which are widely used in large span tubular trusses. The connection was tested in laboratory under tension loading. The tests made it possible to identify the influence of stress distribution on tubes and the need for the use of a shear lag coefficient. The results of the ultimate load capacity demonstrated the viability of the tube sleeve connection use.
Grellner, W; Buhmann, D; Wilske, J
Suicidal gunshot wounds from a livestock stunner with infliction of two shots against the head are extremely rare events. A case with these characteristics is presented and the corresponding literature is reviewed. A 61-year-old butcher was found dead with two entry wounds of the forehead on the right side and in the centre being typical for captive bolt pistols (symmetrically localized powder burns). The issues of the sequence of shots and the capacity of action are discussed on the basis of morphological findings and pathophysiological considerations. A literature review revealed only 4 case reports with double gunshot wounds of the skull caused by "humane killers" (Tovo 1956, Wolff and Laufer 1965, Schiermeyer 1973, Pollak 1977).
We should like to remind users that, since the closure of the self-service stores, nuts, bolts, screws, nails and rivets (Group 47 of the Stores Catalogue) can be obtained, in smaller packages than via EDH, from the 'Emergency Counter' in the Central Stores (Building 73, R-002) upon presentation of a duly completed hard-copy Materials Request form. The 'Emergency Counter' is open Mondays to Fridays from 7.30 a.m. to 11.50 a.m. and from 1.00 p.m. to 4.20 p.m. Information concerning the available packages can be found under the appropriate SCEM reference number in the Stores Catalogue. Logistics Group SPL Division
Lee Sim Yee
Full Text Available The present paper is focused on the bearing stress at failure of double-lap woven fabric kenaf fiber reinforced polymer (KFRP hybrid bonded-bolted joints in experimental frameworks. The effects of different normalized plate width (plate width/hole diameter, W/d, lay-up types and bolt loads were incorporated in current study as specified in testing series. Generally, hybrid joint coupons separated within adhesive layer prior to net-tension failure or bearing/net-tension failure. The bearing stress at failure increased as W/d ratio increment, critical W/d is given as four and three in clamped and finger tight condition respectively. Lay-up types present insignificant effect to bearing stress at failure due to low volume fiber fraction in kenaf fiber composites. Combination of thicker and clamped conditions plate demonstrated greater bearing stress than equivalent finger-tight (FT conditions due to higher load transferred from friction, as expected.
A DOE RL surveillance determined that a test report (WHC-SD-NR-TRP-020) was less than adequate. As a result, WHC removed nine of the previous in-situ tested A325 suspect bolts and contracted with Koon-Hall Testing Corporation to perform hardness and tensile testing and chemical composition analysis of the removed bolts. WHC also contracted with ADVENT Engineering, Inc., to perform an evaluation of the Koon-Hall test results and to respond to the concerns identified in the DOE RL surveillance. The Koon-Hall Laboratory test results and the assessments strongly support the conclusion that the suspect bolts are indeed the equivalent of A325 high-strength, Type-1 bolts and have been properly heat-treated
International Organization for Standardization. Geneva
Applies to bolts and screws of property classes 8.8 to 12.9 in accordance with ISO 898-1 with thread less than M3 for which no breaking and proof loads are indicated in ISO 898-1, as well as to short bolts and screws with nominal diameters 3 mm to 10 mm which cannot be subjected to a tensile test. The minimum breaking torques are not valid for hexagon socket set screws.
Palmer, W.J.; Tomawski, R.J.; Ezekoye, L.I.; Lacey, M.L.
Flange design standards recognize that flanged joints may develop leakage should they be exposed to severe thermal gradients and recommend that such operating conditions be avoided. In nuclear power plants, severe thermal transients may be encountered in many plant and system operating and test conditions. In such applications, conformance with standard design practice may not ensure a leak-tight joint. This paper describes the proper consideration of thermal effects on flanged joints and how that can lead to the development of a successful leak-tight design. Similar procedures may be applied generally to evaluate and upgrade flanged joints in thermal shock applications
Itoh, Hitomi; Ochi, Mayumi; Fujiwara, Isao; Momoo, Takashi
Life estimation was performed for the stress corrosion cracking (SCC) that occurs in deaerated and wet hot pure steam at the bottoms of the threads of bolts made of SCM435 (equivalent to AISI 4137) used in steam turbine. SCC is believed to occur when corrosion pits are formed and grow to critical size, after which SCC is initiated and cracks propagate until the critical fracture toughness value is reached. Calculations were performed using laboratory and field data. The results showed that, for a 40mm diameter bolt with 0.2% offset strength of 820MPa, the critical crack depth for straight-front cracks was 5.4mm. The SCC life depends on the lubricant used; the SCC life estimated from this value is approximately 70,000 hours when graphite is used as a lubricant. (author)
Bunin, Bruce L.
A program was conducted to develop the technology for critical structural joints in composite wing structure that meets all the design requirements of a 1990 commercial transport aircraft. The results of four large composite multirow bolted joint tests are presented. The tests were conducted to demonstrate the technology for critical joints in highly loaded composite structure and to verify the analytical methods that were developed throughout the program. The test consisted of a wing skin-stringer transition specimen representing a stringer runout and skin splice on the wing lower surface at the side of the fuselage attachment. All tests were static tension tests. The composite material was Toray T-300 fiber with Ciba-Geigy 914 resin in 10 mil tape form. The splice members were metallic, using combinations of aluminum and titanium. Discussions are given of the test article, instrumentation, test setup, test procedures, and test results for each of the four specimens. Some of the analytical predictions are also included.
Bunin, Bruce L.; Sagui, R. L.
A program was conducted to develop the technology for critical structural joints for composite wing structure that meets all the design requirements of a 1990 commercial transport aircraft. The results of a comprehensive ancillary test program are summarized, consisting of single-bolt composite joint specimens tested in a variety of configurations. These tests were conducted to characterize the strength and load deflection properties that are required for multirow joint analysis. The composite material was Toray 300 fiber and Ciba-Geigy 914 resin, in the form of 0.005 and 0.01 inch thick unidirectional tape. Tests were conducted in single and double shear for loaded and unloaded hole configurations under both tensile and compressive loading. Two different layup patterns were examined. All tests were conducted at room temperature. In addition, the results of NASA Standard Toughness Test (NASA RP 1092) are reported, which were conducted for several material systems.
Casey-Trott, T M; Millman, S T; Turner, P V; Nykamp, S G; Lawlis, P C; Widowski, T M
The objective of this study was to determine the effectiveness of a nonpenetrating captive bolt, Zephyr-E, for euthanasia of suckling and weaned pigs from 3 to 9 kg (5-49 d of age) using signs of insensibility and death as well as postmortem assessment of traumatic brain injury (TBI). The Zephyr-E was used by 15 stock people to euthanize 150 compromised pigs from 4 farrowing and nursery units from commercial farms and 2 research stations. Brainstem reflexes, convulsions, and heartbeat were used to assess insensibility, time of brain death, and cardiac arrest following Zephyr-E application. Skull fracture displacement (FD) was quantified from computed tomography (CT) scans (n = 24), macroscopic scoring was used to assess brain hemorrhage and skull fracture severity (n = 150), and microscopic scoring was used to assess subdural hemorrhage (SDH) and parenchymal hemorrhage within specific brain regions that are responsible for consciousness and vital function (n = 32). The Zephyr-E caused immediate, sustained insensibility until death in 98.6% of pigs. On average, clonic convulsions (CC) ceased in 82.2 s (± 3.4 SE), brain death was achieved in 144.9 s (± 5.4 SE), and cardiac arrest occurred in 226.5 s (± 8.7 SE). Time of brain death and cardiac arrest differed significantly among stock people (P = 0.0225 and P = 0.0369). Age was positively related to the duration of CC (P = 0.0092), time of brain death (P = 0.0025), and cardiac arrest (P = 0.0068) with shorter durations seen in younger pigs. Average FD was 8.3 mm (± 1.0 SE). Macroscopic scores were significantly different among weight classes for subcutaneous (P = 0.0402) and subdural-ventral (P = 0.0037) hemorrhage with the lowest severity hemorrhage found in the 9-kg weight category. Microscopic scores differed among brain sections (P = 0.0070) for SDH with lower scores found in the brainstem compared to the cerebral cortex and midbrain. Parenchymal hemorrhage differed among brain sections (P = 0.0052) and weight
Full Text Available Structural joints provide connection between structural element (beam, plate etc. in order to construct a whole assembled structure. There are many types of structural joints such as bolted joint, riveted joints and welded joints. The joints structures significantly contribute to structural stiffness and dynamic behaviour of structures hence the main objectives of this paper are to review on method of model updating on joints structure and to discuss the guidelines to perform model updating for dynamic analysis purpose. This review paper firstly will outline some of the existing finite element modelling works of joints structure. Experimental modal analysis is the next step to obtain modal parameters (natural frequency & mode shape to validate and improve the discrepancy between results obtained from experimental and the simulation counterparts. Hence model updating will be carried out to minimize the differences between the two results. There are two methods of model updating; direct method and iterative method. Sensitivity analysis employed using SOL200 in NASTRAN by selecting the suitable updating parameters to avoid ill-conditioning problem. It is best to consider both geometrical and material properties in the updating procedure rather than choosing only a number of geometrical properties alone. Iterative method was chosen as the best model updating procedure because the physical meaning of updated parameters are guaranteed although this method required computational effort compare to direct method.
Sørensen, John Dalsgaard; Thoft-Christensen, Palle
In this paper the preliminary results obtained by tests on tubular joints are presented. The joints are T-joints and the loading is static. It is the intention in continuation of these tests to perform tests on other types of joints (e.g. Y-joints) and also with dynamic loading. The purpose of th...
Yang, Caiqian; Wu, Zhishen; Zhang, Yufeng
The application of hybrid carbon fiber reinforced polymer (HCFRP) sensors was addressed to monitor the structural health of an existing prestressed concrete (PC) box girder bridge in a destructive test. The novel HCFRP sensors were fabricated with three types of carbon tows in order to realize distributed and broad-based sensing, which is characterized by long-gauge length and low cost. The HCFRP sensors were bonded on the bottom and side surfaces of the existing bridge to monitor its structural health. The gauge lengths of the sensors bonded on the bottom and side surfaces were 1.5 m and 1.0 m, respectively. The HCFRP sensors were distributed on the bridge for two purposes. One was to detect damage and monitor the structural health of the bridge, such as the initiation and propagation of new cracks, strain distribution and yielding of steel reinforcements. The other purpose was to monitor the propagation of existing cracks. The good relationship between the change in electrical resistance and load indicates that the HCFRP sensors can provide actual infrastructures with a distributed damage detection and structural health monitoring system. Corrections were made to this article on 13 May 2008. The corrected electronic version is identical to the print version.
Yang Caiqian; Wu Zhishen; Zhang Yufeng
The application of hybrid carbon fiber reinforced polymer (HCFRP) sensors was addressed to monitor the structural health of an existing prestressed concrete (PC) box girder bridge in a destructive test. The novel HCFRP sensors were fabricated with three types of carbon tows in order to realize distributed and broad-based sensing, which is characterized by long-gauge length and low cost. The HCFRP sensors were bonded on the bottom and side surfaces of the existing bridge to monitor its structural health. The gauge lengths of the sensors bonded on the bottom and side surfaces were 1.5 m and 1.0 m, respectively. The HCFRP sensors were distributed on the bridge for two purposes. One was to detect damage and monitor the structural health of the bridge, such as the initiation and propagation of new cracks, strain distribution and yielding of steel reinforcements. The other purpose was to monitor the propagation of existing cracks. The good relationship between the change in electrical resistance and load indicates that the HCFRP sensors can provide actual infrastructures with a distributed damage detection and structural health monitoring system. Corrections were made to this article on 13 May 2008. The corrected electronic version is identical to the print version
Roland E. Koller
Full Text Available Empa’s research efforts in the 1990s provided evidence that a considerable increase of the fatigue strength of welded aluminum beams can be achieved by externally bonding pultruded carbon fiber reinforced polymer (CFRP laminates using rubber-toughened epoxies over the fatigue-weak welding zone on their tensile flange. The reinforcing effect obtained is determined by the stiffness of the unidirectional CFRP laminate which has twice the elastic modulus of aluminum. One can therefore easily follow that an unstressed CFRP laminate reinforcement of welded beams made of steel will not lead to a substantial increase in fatigue strength of the steel structure. This consideration led to the idea of prestressing an external reinforcement of the welded zone. The present investigation describes experimental studies to identify the adhesive system suitable for achieving high creep and fatigue strength of the prestressed CFRP patch. Experimental results (Wöhler-fields of shear-lap-specimens and welded steel beams reinforced with prestressed CFRP laminates are presented. The paper concludes by presenting a field application, the reinforcement of a steel pendulum by adhesively bonded prestressed CFRP laminates to the tensile flanges of the welded box girder. Inspections carried out periodically on this structure revealed neither prestress losses nor crack initiation after nine years of service.
Full Text Available Joint instability creates a clinical and economic burden in the health care system. Injuries and disorders that directly damage the joint structure or lead to joint instability are highly associated with osteoarthritis (OA. Thus, understanding the physiology of joint stability and the mechanisms of joint instability-induced OA is of clinical significance. The first section of this review discusses the structure and function of major joint tissues, including periarticular muscles, which play a significant role in joint stability. Because the knee, ankle, and shoulder joints demonstrate a high incidence of ligament injury and joint instability, the second section summarizes the mechanisms of ligament injury-associated joint instability of these joints. The final section highlights the recent advances in the understanding of the mechanical and biological mechanisms of joint instability-induced OA. These advances may lead to new opportunities for clinical intervention in the prevention and early treatment of OA.
When the United States employs military power, it does so as a joint force. The cornerstone for effective joint force employment remains Service competency, but truly effective Service warfighters must think, plan and fight jointly...
Full Text Available The most common method for the on-farm euthanasia of neonate piglets is reported to be manual blunt force trauma. This paper presents the results of research to evaluate a mechanical non-penetrating captive bolt (the Accles and Shelvoke CASH small animal tool, Birmingham, UK to produce an immediate stun/kill with neonate piglets. One hundred and forty-seven piglets (average dead weight = 1.20 kg ± 0.58 (standard deviation, SD, mean age = 5.8 days (median = 3 were euthanized with the device and demonstrated immediate loss of consciousness, subjectively assessed by behavioural signs and no recovery. The result that 147 out of 147 animals were effectively stun/killed gives a 95% confidence interval for the true percentage of animals that would be effectively stun/killed of 97.5–100% with the use of the CASH small animal tool under the conditions of the current study. This research concludes that the CASH small animal tool, using a 1 grain brown coded cartridge, is suitable for producing a stun/kill in neonate piglets when applied in a frontal/parietal position.
Narro-Diego, Laura; López-González, Leticia; Jarillo, Jose A; Piñeiro, Manuel
The Arabidopsis protein EARLY BOLTING IN SHORT DAYS (EBS), a plant-specific transcriptional regulator, is involved in the control of flowering time by repressing the floral integrator FT. The EBS protein binds the H3K4me3 histone mark and interacts with histone deacetylases to modulate gene expression. Here, we show that EBS also participates in the regulation of seed dormancy. ebs mutations cause a reduction in seed dormancy, and the concurrent loss of function of the EBS homologue SHORT LIFE (SHL) enhances this dormancy alteration. Transcriptomic analyses in ebs mutant seeds uncovered the misregulation of several regulators of seed dormancy including the MADS box gene AGAMOUS-LIKE67 (AGL67). AGL67 interacts genetically with EBS in seed dormancy regulation, indicating that both loci act in the same pathway. Interestingly, EBS functions independently of the master regulator gene of dormancy DELAY OF GERMINATION 1 (DOG1) and other genes encoding chromatin remodelling factors involved in the control of seed dormancy. Altogether, these data show that EBS is a central repressor of germination during seed dormancy and that SHL acts redundantly with EBS in the control of this developmental process. Our observations suggest that a tightly regulated crosstalk among histone modifications is necessary for a proper control of seed dormancy. © 2017 John Wiley & Sons Ltd.
Goekcen, Tahir; Skokova, Kristina A.
This paper reports computational analyses in support of two wedge tests in a high enthalpy arc-jet facility at NASA Ames Research Center. These tests were conducted using two different wedge models, each placed in a free jet downstream of a corresponding different conical nozzle in the Ames 60-MW Interaction Heating Facility. Each panel test article included a metallic separation bolt imbedded in Orion compression-pad and heatshield materials, resulting in a circular protuberance over a flat plate. The protuberances produce complex model flowfields, containing shock-shock and shock-boundary layer interactions, and multiple augmented heating regions on the test plate. As part of the test calibration runs, surface pressure and heat flux measurements on water-cooled calibration plates integrated with the wedge models were also obtained. Surface heating distributions on the test articles as well as arc-jet test environment parameters for each test configuration are obtained through computational fluid dynamics simulations, consistent with the facility and calibration measurements. The present analysis comprises simulations of the nonequilibrium flowfield in the facility nozzle, test box, and flowfield over test articles, and comparisons with the measured calibration data.
Gokcen, Tahir; Skokova, Kristina A.
This paper reports computational analyses in support of two wedge tests in a high enthalpy arc-jet facility at NASA Ames Research Center. These tests were conducted using two different wedge models, each placed in a free jet downstream of a corresponding different conical nozzle in the Ames 60-MW Interaction Heating Facility. Each panel test article included a metallic separation bolt imbedded in Orion compression-pad and heatshield materials, resulting in a circular protuberance over a flat plate. The protuberances produce complex model flowfields, containing shock-shock and shock-boundary layer interactions, and multiple augmented heating regions on the test plate. As part of the test calibration runs, surface pressure and heat flux measurements on water-cooled calibration plates integrated with the wedge models were also obtained. Surface heating distributions on the test articles as well as arc-jet test environment parameters for each test configuration are obtained through computational fluid dynamics simulations, consistent with the facility and calibration measurements. The present analysis comprises simulations of the non-equilibrium flow field in the facility nozzle, test box, and flow field over test articles, and comparisons with the measured calibration data.
American Society for Testing and Materials. Philadelphia
1.1 This practice covers the evaluation of atmospheric galvanic corrosion of any anodic material that can be made into a wire when in contact with a cathodic material that can be made into a threaded rod. 1.2 When certain materials are used for the anode and cathode, this practice has been used to rate the corrosivity of atmospheres. 1.3 The wire-on-bolt test was first described in 1955 (1), and has since been used extensively with standard materials to determine corrosivity of atmospheres under the names CLIMAT Test (CLassify Industrial and Marine ATmospheres) (2-5) and ATCORR (ATmospheric CORRosivity) (6-9). 1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. 1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations p...
Scott, J.J.; Jackson, D.
Exxon has added underground mining operations to the open pits at its Highland uranium mine and mill complex 60 mi northeast of Casper in the Powder River Basin and has, in the process, adopted some innovative mining techniques. A continuous shield miner is being used in conjunction with continuous ground support--thought to be the first truly successful combination of these techniques in a US uranium mine. Highland miners are also making extensive use of ''Split Sets,'' a patented friction rock bolt system invented in 1973, which has proven to be a successful cost-saving substitute for timber supports in Highland's soft, water-saturated, extremely unstable sediments. Initial mine production at Highland began in July 1972, and the mill started up the following October. Design capacity at startup was 2,000 tpd, a figure that has since been expanded to 3,000 tpd through mill modifications but without a major construction program. Current production is about 2 million lb per year of U 3 O 8
Full Text Available Ying-Chao Chou,1,2 Wen-Lin Yeh,2 Chien-Lin Chao,1 Yung-Heng Hsu,1,2 Yi-Hsun Yu,1,2 Jan-Kan Chen,3 Shih-Jung Liu1,2 1Department of Mechanical Engineering, Chang Gung University, 2Department of Orthopedic Surgery, Chang Gung Memorial Hospital, 3Department of Physiology and Pharmacology, Chang Gung University, Taoyuan, Taiwan Abstract: A composite biodegradable polymeric model was developed to enhance tendon graft healing. This model included a biodegradable polylactide (PLA bolt as the bone anchor and a poly(D,L-lactide-co-glycolide (PLGA nanofibrous membrane embedded with collagen as a biomimic patch to promote tendon–bone interface integration. Degradation rate and compressive strength of the PLA bolt were measured after immersion in a buffer solution for 3 months. In vitro biochemical characteristics and the nanofibrous matrix were assessed using a water contact angle analyzer, pH meter, and tetrazolium reduction assay. In vivo efficacies of PLGA/collagen nanofibers and PLA bolts for tendon–bone healing were investigated on a rabbit bone tunnel model with histological and tendon pullout tests. The PLGA/collagen-blended nanofibrous membrane was a hydrophilic, stable, and biocompatible scaffold. The PLA bolt was durable for tendon–bone anchoring. Histology showed adequate biocompatibility of the PLA bolt on a medial cortex with progressive bone ingrowth and without tissue overreaction. PLGA nanofibers within the bone tunnel also decreased the tunnel enlargement phenomenon and enhanced tendon–bone integration. Composite polymers of the PLA bolt and PLGA/collagen nanofibrous membrane can effectively promote outcomes of tendon reconstruction in a rabbit model. The composite biodegradable polymeric system may be useful in humans for tendon reconstruction. Keywords: polylactide–polyglycolide nanofibers, PLGA, collagen, 3D printing, polylactide, PLA, bone-anchoring bolts, tendon healing
Wheatley, Gregory; Kollgaard, Jeffrey R.
Boeing is currently conducting evaluation testing of the Comparative Vacuum Monitoring (CVMTM) system offered by Structural Monitoring Systems, Ltd (SMS). Initial testing has been conducted by SMS, with further test lab validations to be performed at Boeing in Seattle. Testing has been conducted on dog bone type specimens that have been cut at the center line. A notch was cut at one of the bolt holes and a CVM sensor installed on both sides of the plate. The doublers were added and a single line of 4 bolts along the longitudinal center line were used to attach the doubler plates to the dog bone type specimen. In this way, a high load transfer situation exists between the two halves of the dog bone specimen and the doubler plates. The CVM sensors are slightly over 0.004" (0.1mm) in thickness and are installed directly upon the faying surface of the dog bone specimen. Testing was conducted on an Instron 8501 Servohydraulic testing machine at the Department of Mechanical and Materials Engineering, University of Western Australia. The standard laboratory equipment offered by Structural Monitoring Systems, Ltd was used for crack detection. This equipment included the Kvac (vacuum supply) and the Sim8 (flow meter). The Sim8 was electrically connected to the Instron machine so that as soon as a crack was detected, fatigue loading was halted. The aim of the experiment was for CVM to detect a crack on the faying surface of the specimens at a length of 0.050" +/- 0.010". This was accomplished successfully. CVM has been developed on the principle that a small volume maintained at a low vacuum is extremely sensitive to any ingress of air. In addition to the load bearing sensors described above, self-adhesive, elastomeric sensors with fine channels on the adhesive face have been developed. When the sensors have been adhered to the structure under test, these fine channels, and the structure itself, form a manifold of galleries alternately at low vacuum and atmospheric pressure
Sørensen, Karsten Engsig
The article analysis problems connected with corporate joint ventures. Among others the possible conflicts between the joint venture agreement and the statutes of the companies is examined, as well as certain problems connected to the fact that the joint venture partners have created commen control...... over their joint company....
Casey-Trott, T M; Millman, S T; Turner, P V; Nykamp, S G; Widowski, T M
The objective of this study was to determine the effectiveness of a nonpenetrating captive bolt (NPCB), the Zephyr-Euthanasia (Zephyr-E), for euthanasia of neonatal pigletsapplication. Hemorrhage severity and skull fracture displacement (FD) were quantified from computed tomography scans (n=10), macroscopic scoring was used to assess brain hemorrhage and skull fracture (SK) severity (n=100), and microscopic scoring was used to assess subdural (SDH) and parenchymal (PH) hemorrhage within specific brain regions that are responsible for consciousness and vital function (n=10). All 100 piglets were rendered immediately insensible without return to sensibility. On average, clonic convulsions (CC) ceased in 101 s (±7.4 SE), brain death was achieved in 229 s (±9.18 SE), and cardiac arrest occurred in 420 s (±13.57 SE). Time of cardiac arrest differed significantly among stock people when either body weight (BW: P=0.0053) or body mass index (BMI: P=0.0059) was used as a covariate. The BMI was inversely related to the duration of CC (P=0.0227). Moderate to severe hemorrhage severity was reported in 9 of 10 piglets. There was no relationship between FD and BW (P=0.8408) or BMI (P=0.6439). Macroscopic analyses indicated moderate to severe hemorrhage and SK in all piglets. No differences were found among brain sections for SDH (P=0.2302); PH was greater in the cerebral cortex than in the midbrain and brainstem (P=0.0328). The Zephyr-E NPCB reliably caused immediate, sustained insensibility followed by death in neonatal piglets. Postmortem assessment confirmed that application of the Zephyr-E caused widespread, irreversible brain damage.
Aleti, Ashok Reddy
The research presented herein describes the development of durable link slabs for jointless bridge decks based on using FRP grid for reinforcement. Specifically, the ductility of the FRP material was utilized to accommodate bridge deck deformations imposed by girder deflection, temperature variations, and concrete shrinkage. It would also provide a solution to a number of deterioration problems associated with bridge deck joints. The design concept of the link slabs was then examined to form the basis of design for FRP grid link slabs. Improved design of FRP grid link slab/concrete deck slab interface was confirmed in the numerical analysis. The mechanical properties between the FRP grid and concrete were evaluated. The behavior of the link slab was investigated and confirmed for durability. The results indicated that the technique would allow simultaneous achievement of structural need (lower flexural stiffness of the link slab approaching the behavior of a hinge) and durability need of the link slab. Also, the development length results confirm that the bond between the FRP grid and the concrete was highly improved. The overall investigation supports the contention that durable jointless concrete bridge decks may be designed and constructed with FRP grid link slabs. It is recommended that the link slab technique be used during new construction of the bridge decks and in repair and retrofit of the bridge decks.
Zhang, Y W; Jin, D; Xu, C; Zhang, L; Guo, M H; Fang, Z Y
Microtubules are important components of eukaryotic cells, and they play vital roles in cell morphogenesis, carrying of signaling molecules, transport of materials, and establishing the cell polarity. During bolting of biennial plants, cell division and elongation are involved, and cell elongation inevitably involves the microtubules arrangement and expression of related genes. So we deduce that it is of great significance to figure out the mechanism of bolting and flowering in which TUA genes are involved. In the present study, bioinformatic methods were used to predict and identify the α-tubulin gene family (BrTUAs) in Brassica rapa L. ssp pekinensis (Chinese cabbage) through the alignment of AtTUA gene sequence from Arabidopsis thaliana with the B. rapa genome database (http://brassicadb.org/brad/) using the basic local alignment search tool. The change in the structure and functions of BrTUAs during the process of evolution, cis-acting elements in the promoter sequences of BrTUAs, and the expression of the identified genes was also analyzed. Twelve members of the α-tubulin gene family were identified from Chinese cabbage. The gene length, intron, exon, and promoter regions were determined to have changed significantly during the genome evolution. Only five of the 12 members were encoded completely and were observed to differ in their spatial and temporal expression. The five BrTUA promoter sequences contained different numbers of cis-elements responsive to light and low-temperature response, cis-elements responsive among which hormonal responses were significantly different. We also report that the BrTUAs were involved in the regulation of the bolting in Chinese cabbage, and propose that this process could be controlled by regulating the expression of BrTUAs.
Bies, Christian M.; Alaerts, Louis; Bonitz, Frank W. [Westinghouse Electric Germany GmbH, Mannheim (Germany); Devlin, Russell S.; Minogue, Patrick [WesDyne International, Madison, PA (United States)
This article presents the MIDAS VI testing robot used by Westinghouse / WesDyne. This is a remotely operated underwater vehicle which positions ultrasonic probes under camera control. This vehicle makes it possible to substantially reduce the time required for setting up and preparing ultrasonic tests on core baffle former bolts. It has also accelerated the test procedure itself. Test methods have also been developed for bolt types which were hitherto considered incapable of being tested. One of these methods is based on a phased array probe. The article also reports on experiences gained over the course of years in testing core baffle former bolts in European nuclear power plants using the SUPREEM testing robot.
The present study has two objectives. Firstly, to present the fundamental principles of the method of support with bolts. Secondly, to provide a plan for the preparation of tests, whose results will lead to the acceptance or rejection of the method of roof support with bolts in the mines of the Rio Escondido coal region. 10 refs., 9 figs., 3 tabs.
Radiographs are used in diseases of the joints to confirm the clinical diagnosis of joint disease, determine the type of joint disease, and evaluate the extent of clinically known disease. The radiographic findings may be either consistent or inconsistent with the clinical diagnosis. If inconsistent, an alternative diagnosis should be made on the basis of the radiographic appearance of the disease process. On other occasions, joint disease is observed on a radiograph obtained for some other reason, such as for peripheral trauma; on a chest radiograph demonstrating changes in the spine or pectoral girdle; or on radiographs of the abdomen and pelvis revealing abnormalities of the spine, sacroiliac joints, or hips. In the latter situations, the joint disease should be categorized and included in the radiographic report. There are four principal radiographic signs of joint abnormalities or joint disease. These are (1) abnormalities of the apposing margins of both bones at a joint, (2) change in the width of the joint space, usually narrowing, but occasionally, widening due to an increase in synovial fluid, (3) malalignment of the joint (subluxation or dislocation with the joint margins no longer in apposition), and (4) periarticular swelling due to distension of the joint capsule. The most common findings are narrowing of the joint space and abnormalities of the apposing articular margins of bone
Fischer, Boromir; Giller, Madeleine; Neidel, Andreas; Riesenbeck, Susanne [Siemens AG - Gasturbinenwerk Berlin (Germany). Energy Sector Werkstoffprueflabor
The nut of a horizontal joint fastener cracked upon tightening during assembly in an industrial steam turbine factory. It was previously used in an over-pressure test, but was otherwise not yet used in service. Nut and bolt were made of the nickel-based superalloy Nimonic 80A, a precipitation-hardenable wrought high-strength alloy with excellent creep and corrosion properties. Such alloys usually get a complex heat treatment after hot-rolling, comprising homogenizing and multiple ageing cycles. The subject nut failed due to an extreme case of mixed grain size which detrimentally affected mechanical properties and was attributed to an insufficient degree of deformation during hot rolling.
Mayfield, A E; Hanula, J L
The redbay ambrosia beetle, Xyleborus glabratus Eichhoff, is a non-native invasive pest and vector of the fungus that causes laurel wilt disease in certain trees of the family Lauraceae. This study assessed the relative attractiveness and suitability of cut bolts of several tree species to X. glabratus. In 2009, female X. glabratus were equally attracted to traps baited with swampbay (Persea palustris (Rafinesque) Sargent) and camphortree (Cinnamomum camphora (L.) J. Presl), which were more attractive than avocado (Persea americana Miller), lancewood (Ocotea coriacea (Swartz) Britton), and sweetbay (Magnolia virginiana L.). These species were more attractive than loblolly bay (Gordonia lasianthus (L.) J. Ellis). X. glabratus entrance hole density and emergence from caged bolts were highest on swampbay and camphortree. In 2010, swampbay was significantly more attractive to X. glabratus than sassafras (Sassafras albidum (Nuttall) Nees), yellow poplar (Liriodendron tulipifera L.), and eastern redbud (Cercis canadensis L.). Sassafras bolts end sealed with a liquid wax-and-water emulsion were more attractive to X. glabratus than end-sealed bolts of yellow poplar and redbud. Relative to unsealed bolts, end seal decreased X. glabratus entrance hole density on swampbay and decreased granulate ambrosia beetle (Xylosandrus crassiusculus (Motschulsky)) trap catch, entrance hole density, and adult emergence from swampbay. X. crassiusculus was not attracted to sassafras, yellow poplar, and redbud and was not more attracted to manuka oil than to unbaited traps. Sassafras was more attractive to X. glabratus than previously reported and supported reproducing populations of the insect. End sealing bolts with a wax-and-water emulsion may not be optimal for attracting and rearing ambrosia beetles in small logs.
Puchała, Krzysztof; ElŻbieta, Szymczyk; Jachimowicz, Jerzy; Bogusz, Paweł
Mechanical joints (e.g. bolted) used for decades are proved to be reliable. They can be assembled and applied in very rough conditions since they are less sensitive to environmental effects than other types of joints (e.g. adhesive). Therefore, they are still employed in aircraft design. High specific stiffness and strength of composite materials (especially CFRP) cause a continuous increase in their usage in aircraft structures. In general, composites are brittle materials and more notch sensitive than metal alloys. Hole making is a necessary stage in manufacturing of a mechanical joint. Holes vicinities are the areas of high stress concentrations and determine load capability of the whole structure. Therefore, mechanical joints of composite parts require a special focus during both a designing and a manufacturing process. The aim of the paper is analysis of potential local material weakness/deterioration caused by a drilling process and its influence on the global response of a mechanical joint. The specimen in the form of a double-shear joint was analyzed. The weakened areas were identified on the basis of NDT ultrasonic analysis. A simple gradient material model was proposed to describe the hole vicinity. Numerical simulations were performed and compared to experimental results.
Full Text Available This study was aimed to describe cortisol hormone concentration and meat quality which were produced in beef cattle stunned with captive bolt stun gun before slaughtering. Blood and meat samples were taken from Brahman cross steers (n= 11 in two abattoirs located in West Java and Banten. Blood samples were collected immediately after slaughtering. Cortisol hormone concentration in the serum was measured by using radioimmunoassay (RIA. The descriptive, correlation, and regression analyses were used to interprete data. Meat quality assessment was based on pH, cooking loss, and complete drainage of blood. The average of cortisol hormone concentration was 26.59 ng/mL. Meat pH at 1 h postmortem and 24 h postmortem were 6.65 and 6.21, respectively. Meat cooking loss was 26.77%. Blood drainage in meat samples of each cattle showed complete drainage. There was a significant correlation (P<0.05 between cortisol concentrations and pH at 1 hour postmortem as well as cortisol concentration and cooking loss. There was no significant correlation between pH at 24 h postmortem and cooking loss. Cattle was stunned with a captive bolt stun gun before slaughtering produced meat with complete blood drainage but had high cortisol hormone concentration and pH ultimate.
... Find a Hand Surgeon Home Anatomy MP Joint Arthritis Email to a friend * required fields From * To * ... important for both pinching and gripping. MP joint arthritis is most common in the thumb and index ...
Lindenberg, Siegwart; Foss, Nicolai Juul
We contribute to the microfoundations of organizational performance by proffering the construct of joint production motivation. Under such motivational conditions individuals see themselves as part of a joint endeavor, each with his or her own roles and responsibilities; generate shared...... representations of actions and tasks; cognitively coordinate cooperation; and choose their own behaviors in terms of joint goals. Using goal-framing theory, we explain how motivation for joint production can be managed by cognitive/symbolic management and organizational design....
Albert E. Mayfield; James L. Hanula
The redbay ambrosia beetle, Xyleborus glabratus Eichhoff, is a non-native invasive pest and vector of the fungus that causes laurel wilt disease in certain trees of the family Lauraceae. This study assessed the relative attractiveness and suitability of cut bolts of several tree species to X. glabratus. In 2009, female X. glabratus were equally attracted to traps...
May, C.; Opperman, E.; Mckeel, C.
The Transuranic (TRU) Disposition Project at Savannah River Site will require numerous transfers of radioactive materials within the site boundaries for sorting and repackaging. The three DOT Type A shipping packagings planned for this work have numerous bolts for securing the lids to the body of the packagings. In an effort to reduce operator time to open and close the packages during onsite transfers, thus reducing personnel exposure and costs, an evaluation was performed to analyze the effects of reducing the number of bolts required to secure the lid to the packaging body. The evaluation showed the reduction to one-third of the original number of bolts had no effect on the packagings capability to sustain vibratory loads, shipping loads, internal pressure loads, and the loads resulting from a 4-ft drop. However, the loads caused by the 4-ft drop are difficult to estimate and the study recommended each of the packages be dropped to show the actual effects on the package closure. Even with reduced bolting, the packagings were still required to meet the 49 CFR 178.350 performance criteria for Type A packaging. This paper discusses the effects and results of the drop testing of the three packagings.
Kim, Dong Hak; Seo, Ki Seog; Lee, Sang Jin; Lee, Kyung Ho; Kim, Jeong Mook
If a type IP-2 transport package were to be subjected to a free drop test and a penetration test under the normal conditions of transport, it should prevent a loss or dispersal of the radioactive contents and a more than 20% increase in the maximum radiation level at any external surface of the package. In this paper, we suggested the analytic method to evaluate the structural safety of a type IP-2 transport package using a thick steel plate for a structure part and a bolt for tying a bolt. Using an analysis a loss or disposal of the radioactive contents and a loss of shielding integrity were confirmed for two kinds of type IP-2 transport packages to transport radioactive waste drums from a waste facility to a temporary storage site in a nuclear power plant. Under the free drop condition the maximum average stress at the bolts and the maximum opening displacement of a lid were compared with the tensile stress of a bolt and the steps in a lid, which were made to avoid a streaming radiation in the shielding path, to evaluate a loss or dispersal of radioactive waste contents. Also a loss of shielding integrity was evaluated using the maximum decrease in a shielding thickness. To verify the impact dynamic analysis for free drop test condition and evaluate experimentally the safety of two kinds of type IP-2 transport packages, free drop tests were conducted with various drop directions
Kiran M. Kothari; Gerard T. Pittard
Utilities in the U.S. operate over 75,000 km (47,000 miles) of old cast-iron pipes for gas distribution. Bell-and-spigot joints that connect pipe sections together tend to leak as these pipes age. Current repair practices are costly and highly disruptive. The objective of this program is to design, test and commercialize a robotic system capable of sealing multiple castiron bell and spigot joints from a single pipe entry point. The proposed system will perform repairs with the pipe in service by traveling through the pipe, cleaning each joint surface, and installing a stainless-steel sleeve lined with an epoxy-impregnated felt across the joint. This approach will save considerable time and labor, minimize excavation, avoid traffic disruption, and eliminate any requirement to interrupt service to customers (which would result in enormous expense to utilities). Technical challenges include: (1) repair sleeves must compensate for diametric variation and eccentricity of old cast-iron pipes; (2) the assembly must travel long distances through pipes containing debris; (3) the pipe wall must be effectively cleaned in the immediate area of the joint to assure good bonding of the sleeve; and (4) an innovative bolt-on entry fitting is required to conduct safe repair operations on live mains.
Full Text Available The columnar jointed rock mass (CJR, composed of polygonal cross-sectional columns cut by several groups of joints in various directions, was exposed during the excavations of the Baihetan hydropower station, China. In order to investigate the unloading performances and the stability conditions during excavation of the columns, an experimental field study was performed. Firstly, on-site investigations indicated that the geotechnical problems, including rock relaxation, cracking and collapse, were the most prominent for the CJR Class I that contains intensive joint network and the smallest column sizes. Comprehensive field tests, including deformation measurement by multi-point extensometers, ultrasonic wave testing, borehole television observation and stress monitoring of rock anchors, revealed that the time-dependent relaxation of the CJRs was marked. The practical excavation experiences for the Baihetan columnar jointed rock masses, such as blasting scheme, supporting time of shotcrete and rock bolts, were presented in the excavations of the diversion tunnels. These detailed investigations and practical construction experiences can provide helpful information for similar geotechnical works in jointed rock mass.
The use of hydraulic bolts for coupling in order to shorten the maintenance critical path in turbo generator sites; Uso de tornillos hidraulicos para acoplamiento a fin de acortar la ruta critica del mantenimiento en sitios de turbogeneradores
Garcia Arelle, Carlos [Turbomaquinas S. A. de C.V., La Piedad, Michoacan (Mexico)
The use of hydraulic bolts has permitted to diminish the time in the critical path of the maintenance, attaining to reduce the total costs and avoiding that some bolts are stuck, benefits the on time planning of the maintenance. The bolts of radial adjustment provide significant benefits to the General Turbine operator. The hydraulic bolts avoid the normal problems of the conventional coupling bolts and rapidly help to re-establish the couple concentricity. The bolts are individually designed to meet a specific geometry and are a direct replacement of the conventional bolts. [Spanish] El uso de tornillos hidraulicos ha permitido disminuir el tiempo de la ruta critica del mantenimiento, logrando reducir los costos totales y al evitar que algun tornillo se atore, beneficia la planeacion de mantenimientos a tiempo. Los tornillos de ajuste radial proveen beneficios significativos al operador de la Turbina General. Los tornillos hidraulicos eliminan los problemas normales de los tornillos de acoplamiento convencionales y rapidamente ayudan a restablecer la concentridad del cople. Los tornillos son disenados individualmente para completar una geometria especifica y son un reemplazo directo de los tornillos convencionales.
Balasubramanian, V.; Ravisankar, V.; Madhusudhan Reddy, G.
This article reports the effect of postweld aging treatment on fatigue behavior of pulsed current welded AA 7075 aluminum alloy joints. AA7075 aluminum alloy (Al-Zn-Mg-Cu alloy) has gathered wide acceptance in the fabrication of light weight structures requiring high strength-to weight ratio, such as transportable bridge girders, military vehicles, road tankers, and railway transport systems. The preferred welding processes of AA7075 aluminum alloy are frequently gas tungsten arc welding (GTAW) process and gas metal arc welding (GMAW) process due to their comparatively easier applicability and better economy. Weld fusion zones typically exhibit coarse columnar grains because of the prevailing thermal conditions during weld metal solidification. This often results inferior weld mechanical properties and poor resistance to hot cracking. In this investigation, an attempt has been made to refine the fusion zone grains by applying pulsed current welding technique. Rolled plates of 10 mm thickness have been used as the base material for preparing multipass welded joints. Single V butt joint configuration has been prepared for joining the plates. The filler metal used for joining the plates is AA 5356 (Al-5Mg (wt.%)) grade aluminum alloy. Four different welding techniques have been used to fabricate the joints and they are: (i) continuous current GTAW (CCGTAW), (ii) pulsed current GTAW (PCGTAW), (iii) continuous current GMAW (CCGMAW), and (iv) pulsed current GMAW (PCGMAW) processes. Argon (99.99% pure) has been used as the shielding gas. Rotary bending fatigue testing machine has been used to evaluate fatigue behavior of the welded joints. Current pulsing leads to relatively finer and more equi-axed grain structure in GTA and GMA welds. Grain refinement is accompanied by an increase in fatigue life and endurance limit. Simple postweld aging treatment applied to the joints is found to be beneficial to enhance the fatigue performance of the welded joints.
Kerley, James J.
The method of retroduction, adapted from the doctoral thesis of Dr. A. Croce, relies on a process of dialectic questioning that begins with the information sought, proceeds to Given items (either in the form of dimensions or limits of research). and to Known mathematical forms of analysis in design or to principles of study in research. Finally, analysis and synthesis are used to abstract the dielectic questions and to arrive at the information desired. This method is used to solve the engineering design problem of a beam and to determine why bolts and nuts vibrate apart. Both mathematical analysis and dialectic logical analysis are utilized. Results are provided of tests conducted to check the retroductive study of why and how nuts back off.
Kopsaftopoulos, Fotis P; Fassois, Spilios D
A comparative assessment of several vibration based statistical time series methods for Structural Health Monitoring (SHM) is presented via their application to a scale aircraft skeleton laboratory structure. A brief overview of the methods, which are either scalar or vector type, non-parametric or parametric, and pertain to either the response-only or excitation-response cases, is provided. Damage diagnosis, including both the detection and identification subproblems, is tackled via scalar or vector vibration signals. The methods' effectiveness is assessed via repeated experiments under various damage scenarios, with each scenario corresponding to the loosening of one or more selected bolts. The results of the study confirm the 'global' damage detection capability and effectiveness of statistical time series methods for SHM.
Full Text Available The paper presents the problems regarding bolted flange connections with gaskets used in chemical, petrochemical and energy industry. The aim of the research is to present state of knowledge regarding pipelines and apparatus in industrial installations and rules and regulations regarding flange connections tightness. Additionally a calculation example regarding flange connection according to ASME VIII DIV 1 requirement and then detailed Finite Element Analysis presented; impact of nonlinear material properties (gasket loading unloading curves on the connection tightness for complex loading programme is shown. It is finally concluded that in addition to usual design calculations more precise calculation is needed to fully verify behaviour of sealed connection at complex extreme variable loadings. Material aspect is very important at designing, testing, service and maintenance; taking it into consideration may avoid many problems related to safe exploitation.
... it right and well-and their feeling the same way about you. All frills and lobbying aside, the essence of jointness is understanding and trust. As General Colin Powell stated in the first edition of Joint Pub 1, "jolnt warfare is team warfare." But what about seamlessness, synergy, joint doctrine, interoperability, and all the other buzzwords? Let's examine some of the more prevalent ones.
Performance of a flange joint is characterised mainly by its 'strength' and 'sealing capability'. A number of analytical and experimental studies have been conducted to study these characteristics under internal pressure loading. However, with the advent of new technological trends for high temperature and pressure applications, an increased demand for analysis is recognized. The effect of steady-state thermal loading makes the problem more complex as it leads to combined application of internal pressure and temperature. The present design codes do not address the effects of temperature on the structural integrity and sealing ability. In addition, the available design solutions do not solve problems of failure of a gasketed flange joint even under bolt up and internal pressure loading conditions. To investigate joint strength and sealing capability under combined internal pressure and different steady-state thermal loading, a 3D nonlinear finite element analysis (FEA) of a gasketed flange joint is carried out and its behaviour is discussed. To determine the safe operating conditions or the actual joint load capacity, the joint is further analyzed for different internal pressures keeping the temperature constant
Balasubramanian, V.; Ravisankar, V.; Madhusudhan Reddy, G.
High strength aluminium alloys (Al-Zn-Mg-Cu alloys) have gathered wide acceptance in the fabrication of light weight structures requiring high strength-to weight ratio, such as transportable bridge girders, military vehicles, road tankers and railway transport systems. The preferred welding processes of high strength aluminium alloy are frequently gas tungsten arc welding (GTAW) process and gas metal arc welding (GMAW) process due to their comparatively easier applicability and better economy. Weld fusion zones typically exhibit coarse columnar grains because of the prevailing thermal conditions during weld metal solidification. This often results inferior weld mechanical properties and poor resistance to hot cracking. In this investigation, an attempt has been made to refine the fusion zone grains by applying pulsed current welding technique. Rolled plates of 6 mm thickness have been used as the base material for preparing single pass welded joints. Single V butt joint configuration has been prepared for joining the plates. The filler metal used for joining the plates is AA 5356 (Al-5Mg (wt%)) grade aluminium alloy. Four different welding techniques have been used to fabricate the joints and they are: (i) continuous current GTAW (CCGTAW), (ii) pulsed current GTAW (PCGTAW), (iii) continuous current GMAW (CCGMAW) and (iv) pulsed current GMAW (PCGMAW) processes. Argon (99.99% pure) has been used as the shielding gas. Fatigue properties of the welded joints have been evaluated by conducting fatigue test using rotary bending fatigue testing machine. Current pulsing leads to relatively finer and more equi-axed grain structure in gas tungsten arc (GTA) and gas metal arc (GMA) welds. In contrast, conventional continuous current welding resulted in predominantly columnar grain structures. Grain refinement is accompanied by an increase in fatigue life and endurance limit
Cruijssen, F.C.A.M.; Borm, P.E.M.; Dullaert, W.; Hamers, H.J.M.
This paper introduces a framework for joint hub network development. Building a joint physical hub for transhipment of goods is expensive and therefore involves considerable risks for the cooperating companies. In a practical setting, it is unlikely that an entire network will be built at once.
Graighead, Norwood D., II; Preliasco, R. J.; Hult, T. D.
Joint with four-bar-linkage geometry has following attributes: Springs to fully extended fully folded positions. Automatically locks in its extended position. Joint combines zero backlash, positive locking, and centerline pivoting. Used in folding tool handles, portable antenna booms, and many other deployable structures.
Vanelderen, P.; Szadek, K.M.; Cohen, S.P.; Witte, J.; Lataster, A.; Patijn, J.; Mekhail, N.; van Kleef, M.; van Zundert, J.
The sacroiliac joint accounts for approximately 16% to 30% of cases of chronic mechanical low back pain. Pain originating in the sacroiliac joint is predominantly perceived in the gluteal region, although pain is often referred into the lower and upper lumbar region, groin, abdomen, and/ or lower
The temporomandibular joint (TMJ) connects your jaw to the side of your head. When it works well, it enables you to talk, chew, and yawn. For people with TMJ dysfunction, problems with the joint and muscles around it may cause Pain that travels through the face, jaw, ...
Olsen, Bo Sanderhoff; Henriksen, M G; Søjbjerg, Jens Ole
The effect of simultaneous ulnar and radial collateral ligament division on the kinematics of the elbow joint is studied in a cadaveric model. Severance of the anterior part of the ulnar collateral ligament and the annular ligament led to significant elbow joint instability in valgus and varus...
The paper presents the progress report of the Joint European Torus (JET) Joint Undertaking, 1986. The report contains a survey of the scientific and technical achievements on JET during 1986; the more important articles referred to in this survey are reproduced as appendices to this Report. The last section discusses developments which might improve the overall performance of the machine. (U.K.)