Unsupported sleepers, which are found sporadically along railway ballasted track, cause various problems from track geometry management, such as a rapid deterioration of the track condition. In this study, we conducted on-site measurement of the response in commercial line and a follow-up survey of the amount of the gap between the bottom of the sleeper and upper surface of ballast (gap value). As a result, it is confirmed that the rail seat load is smaller and the vertical displacement of the sleeper is larger at the sites of unsupported sleepers than at the normal ones; the phenomenon can be reproduced by numerical calculation; the unsupported sleeper location is almost predictable, and the gap value gradually increases and affects the progress of longitudinal level irregularity.
In the slab track laid in a cold area, gaps are generated between the track slab and the filling layer. Currently, the gap is repaired based on the amount of gap measured. In the future, new repair criteria based on a characteristics of load resistant capacity of track slab will be required. Therefore, loading test of slab model specimens and finite element analysis of slab tracks were performed. Based on these results, a repair criteria using displacement of the track slab was proposed.
With the amendment of Port and Harbor Act, the necessity of reinforcement work for piers possessed by private business operators is increasing. At the same time, construction method which can be easily applied is desiring for the demand of laborsaving in construction field these years. Based on these, authors proposed reinforcement methods focusing on pile head of piers. In this paper, cyclic loading tests towards on piers applied by these reinforcement methods are carried out to confirm the strengthening effect and validity in reinforcement design. As a result, strengthening effect and validity in design of proposed methods are verified.
Elasto-plastic large deflection static/dynamic analysis using beam elements is one of the most practical, yet reliable tools in strength-related stability/seismic design methods for steel structures. Among them, the strain-based seismic verification method (SBSVM) is believed to be versatile and thus applicable to not only steel bridge piers, but also a variety of steel bridges such as arch, truss, cable-stayed bridges etc. However, some criticisms against the method have been raised recently by some researchers. The present paper is intended to clear up the misunderstandings by presenting the full procedure of SBSVM using steel large scale double arch-rib model structures tested in a research laboratory of a bridge fabricator.
Previous studies have investigated the load-distributing effect of deteriorated steel girder bridges. However, if end cross beams and an RC slab which can behave as load-distributing members have damage, the load-bearing capacity of the deteriorated bridges needs to be clarified. Thus the interactive load-bearing capacity and vertical displacement at bridge supports of a small H-beam bridge model were analyzed by using the finite displacement method in this study. The analytical result showed that the vertical load above the focused girder was distributed to the adjacent girders via the end cross beams and the RC slab even if the members had damage. However, the stiffness decreations of the end cross beams and the slab reduce the load-bearing capacity of the damaged girder end.
Many bridges and infrastrucutures were damaged by the seismic waves in the 2016 Kumamoto Earthquakes, and in this research, we focused on the Aso-bridge which collapsed immediately after the main shock. A huge landslide happened after the earthquakes and Aso-bridge, which was constructed in the same location of the landslide, totally collapsed. There are a couple of reports that four main factors might have contributed to this collapse; (1) seismic wave, (2) ground deformation, (3) landslide material load increase on the bridge, (4) basement ground collapse. In this paper, a numerical analysis of the Aso-Bridge collapse was conducted using the ASI-Gauss code, which is one of the finite element method utilizing beam elements. Then, we have discussed the main factor of the Aso-bridge collapse.
The Japanese specifications for highway bridges have been revised in 2017, the specification requires verifications of the resistances of high strength bolted joint in not only slip behavior but also after slip behavior. After slip behavior of friction type joint is supposed to be similar to that of bearing type joint. In this study, tensile tests had been conducted to clarify slip and after slip behavior of high strength bolt friction type joints with extended filler plate and indirect connection. As a result, extended filler plate and indirect connection can alleviate the reduction of slip load and bolt breaking load. Extension of filler and splice plates has the advantage against the reduction of these loads.
In recent years, with the aging of bridges, many corrosion damages of steel bridges have been reported. In the case of replacing the splice plate against corrosion damage of the steel girder joint part, there is a method of installing an attaching additional member and replacing the corrosion damaged portion of the girder with a new member. However, there are cases where the space is narrow is difficult. In this study, FEM analysis considering the construction step was carried out for the replacement of the lower flange splice plate of the steel I girder, so even if there is less space under the girder. We propose effective installation position and cross section shape of the attached the additional steel plates.
Stress measurements of the newly built Koubo dam radial gates were executed to obtain stress values in non-deteriorated condition for the future maintenance. While paying attention to the axial stress of arm near the trunnion pin, observed data were compared with FEM analysis results considering trunnion pin axial direction imperfection. Although the randomness of the imperfection became clear from these comparative results, the limit of the error to the analysis values not considering the imperfection was understood. By utilizing these findings, future maintenance of the gates may be rationalized.
Recently inconvenience on the community due to infrastructure construction are required to minimize as much as possible. In order to construct temporary bridges quickly, we are considering using the double end plate connection utilized high strength bolted tensile joint. In the bolted tensile joint, it is desirable that the joint surface is flat and completely adhered by the load transmission mechanism. However, since it is a prerequisite to reuse a member of temporary bridges as temporary structures, there is concern that the joint surface may be deformed by repeated use. In this study, the bending strength and the behavior when filler plates were inserted on the double end plate connection was examined with FEM analysis.
The incline or the settlement of an abutment or a pier due to aged deterioration, flood and earthquake cause inappropriate support condition of a line bearing, which could decrease the load carrying capacity of a steel girder end. In this study, the load carrying capacity and resistance mechanism of the riveted steel girder end was evaluated according to the support position movement of the line bearing by carrying out the loading experiment with the full scale specimens of girder end and finite element analysis.
The railway steel girders were strengthened by the welding of channel-shaped steels or steel plates during the early Showa era. However, the cracks at welded metal between the girder and the strengthening members were often found by the periodic inspection. Furthermore, the corrosion in the upper frange within the strengthening members was also found where the crack initiated and propagated portion. In this paper, the ultimate strength of strengthened steel girder with crack and corrosion was investigated by the loading test as well as finite element analysis. As a result, it was shown that the ultimate strength of strengthened girder was related to the buckling of strengthening members. Furthermore, the condition to prevent the buckling of strengthening members was proposed.
The water tank was damaged by the Kumamoto earthquake. The author's group has conducted a field survey. According to various reports, SUS tanks were damaged even in the latest designs after the 1995 Hyogoken-Nanbu Earthquake. The cause of the damage here is thought to be mainly due to the sloshing phenomenon and the bulging phenomenon. In 2012, the authors focused on the sloshing phenomenon in response to the 2011 Great East Japan Earthquake, and conducted vibration tests on actual SUS tanks. In this paper, the damage investigation of the SUS tank in the Kumamoto earthquake is shown. Also review the strain data of the vibration experiment. The result is compared with the damage of the SUS tank.
This study proposes an irregularity detection system of sabo facility foundation using a monitoring data of groundwater level utilizing the multipattern neural network. The proposed system predicts the daily groundwater level of the measurement point at the lowest sea level by a neural network function associated with the other measurement points. If the difference between the prediction and the observation of a groundwater level exceeds a certain threshold level, the system recognizes that an irregularity might occur. The proposed system shows better fitting than the conventional method, because the observed data includes multipatterns relationship in the observation.
During the 2011 Great Japan earthquake, approximately 23 million tons of disaster debris was generated. If disaster debris is poorly managed, the waste can have significant environmental and public health impacts and, finally, it can affect the overall recovery process. In this paper, a risk-based framework for estimating the tsunami disaster wastes in a region affected by the anticipated Nankai Trough earthquake is presented taking into consideration uncertainties associated with the prediction of tsunami hazard and structural vulnerability. As an illustrative example, risk curves of tsunami disaster waste are provided for several locations in Mie Prefecture. The proposed framework can contribute to developing a strategy to manage the tsunami debris for the disaster resilience enhancement.
Social infrastructures such as roads, bridges, and tunnels are aging, and its maintenance and management are an urgent issue. The goal of this study was to estimate the deformation, fatigue, and deterioration of bridges, by using digital twin model. To accomplish this, first, we modeled of entire existing long bridge with 3D shell and solid elements. Next, we estimated the deformation of the bridge under vehicle load and daily temperature change by applying linear static analysis. The numerical results were within the 95% confidence interval of the actual measurement, in the case of vehicle load. Further, the model could qualitatively represent the deformation of the bridge under daily temperature change.
In this paper several algebraic solutions concerning Boussinesq's and Cerruti's problems in Huber type's anisotropy, which belongs to special case of transversely isotropic body, are respectively found from modified displacement functions corresponding to Galerkin vector shown by R.D.Mindlin. When anisotropic parameter becomes unit, these solutions are respectively reduced to rigorous solutions developed independently by Boussinesq and Cerruti. Further numerical values obtained from above methods are respectively compared with results of Fourier series about two classical problems. It is verified that values of this manner coincide with results of series except numerical value of function 1/R, as R indicates modified radius vector.
The purpose of this study is to verify the accuracy of the improved ZIG-ZAG theory in free vibration analysis of anisotropic laminates and isotropic plates. Exact solutions of the natural frequency of anisotropic laminates are obtained in order to verify the accuracy of the improved ZIG-ZAG theory. The improved ZIG-ZAG theory is applied to the free vibration analysis of anisotropic laminates and isotropic plates, the accuracy of this theory is examined by using the exact solutions. The eﬀective selecting method of the displacement fields in the ZIG-ZAG theory is clarified.
The partial factors of the performance verification equation for the ultimate limit state of RC structural member subjected to bending moment and axial force are studied based on the reliability-based design. The first-and second order reliability methods with the importance sampling update are used for the reliability analysis. The influence of the deviation of the coefficient of variations (COV) of four design variables on the partial factors is studied for different eccentricities of the RC section. Further, methods for the identification of target reliability levels and other important issues are discussed. The procedure to determine the partial factors demonstrated in this study can be applicable for other performance verification equations stipulated in the JSCE' Specifications and other design standards.
This paper summarizes loading test results of RC box culverts with two tunnels subjected to fault displacement. The specimens are 1/4 scaled model, supported by pin bearing as the fault crossing at 45 degrees of the tunnel axis and loaded vertically at the top slab to reproduce the soil pressure. Loading up to highly nonlinear region which greatly exceeded the yielding of reinforcing bars is performed and displacement transducers, strain gauges, image processing and optical fibers are utilized for measurements. The failure mode of RC box culverts subjected to fault displacement is clarified and their ductility is verified by test results. Experimental results will be used as the benchmark for design methods and damage evaluation by nonlinear analysis.
This study has developed a calculation formula for the deformation of buried pipes that are affected by the ground displacement. Assuming that the ground around a pipe yields to constant ground reaction force, the approximate equation of deflection and cross-sectional force is obtained using the beam-column basic equations. The deflection can be calculated from the Young's modulus, section conditions of the pipe and the ground reaction force. those can be applied to various pipes. The formula can be evaluated the bending moment increases when compressive force is applied, and the pipe deformation can be evaluated with the minimum necessary parameters.
The present paper assesses and discusses seismic performance of an underground reinforced (RC) structure. For this purpose, the authors applied a nonlinear three dimensional (3D) dynamic analysis and a pushover structural analysis to examine the effects of structural profile, input ground motion angle and cyclic static loading on global as well as local response properties of the target structures. As a result, the 3D analysis demonstrates that the wall well hinder global structural deformation even under the most critical input wave angle. In addition, the pushover analysis, which includes equivalent dynamic earth pressures, can provide approximately the same degrees of deformation with that of the 3D dynamic analysis if the cyclic static loading is considered.
At Great Hanshin Awaji Earthquake occurred on Jun. 17, 1995, many infrastructures suffered severe damage. The central pillars in the Daikai-subway station circumferentially cracked and/or axially crashed from the lower part. These damage may not be due to horizontal earthquake motion but due to vertically transmitted thrust-up wave. In this paper, to numerically recreate a similar damage situation, elasto-plastic dynamic response analysis for the station model was carried out by thrusting up the level of the bottom of the base slab including ground layer. From this study, it is identified that circumferential crack and vertical crash of the pillars at the quake can be recreated numerically due to thrusting up during 5 ms with the velocity of 200 kine and 400 kine, respectively.
This study examined low cycle fatigue behavior of cruciform welded joints containing incomplete penetration. Six types of specimens with different sizes of weld penetrations and weld leg lengths were tested under cyclic plastic strains. The test results revealed that the fatigue strength and cracking patterns depend on the ratio of the weld penetration to the main plate thickness and the ratio of the weld leg length to the main plate thickness, respectively. Then, elasto-plastic finite element analyses including the effective notch concept were performed. The results indicate that the fatigue strength and cracking pattern of the specimens can be correlated with the local strain distribution around the effective notch.
Focusing on the load redistribution of statically indeterminate structures under mega earthquake motions, we investigated the ultimate behavior of the entire structure after a certain member reached its maximum load carrying capacity point. First, we newly developed a program that automatically builds a detailed entire bridge finite element model using shell elements, and outlined its concept. Next, the ultimate behavior of the upper-deck type steel arch bridge up to the safety limit of the entire system due to the damage accompanied by buckling of multiple members was analyzed by pushover analysis using an accurate shell element model. As a result, it was shown that there was a margin of about 1.4 times up to an entire structure reached the maximum load carring capacity after a certain member reached its load carring capacity.
A spherical sliding bearing (SSB) has been only used as a seismic isolation bearing for buildings in Japan. In general, the behavior of the SSB under seismic forces have been the main focus on this bearing. In order to apply the SSB to bridges, it is necessary to ensure that the SSB performs properly under all design loads. Therefore, this study investigated the behavior of the SSB under live load actions by static cyclic loading tests on a bridge superstructure model supported by single SSBs. Especially, the rotation of the bearing and the displacement of the slider followed by the deflection of the superstructure were investigated. Also, the finite element analyses were carried out to simulate the static loading tests and to investigate the behavior of the bearing.
The damage to water pipelines in past earthquakes includes numbers of leakage in jointed pipeline due to pullout behavior of non-anti-seismic joints. This paper reports on advantageous effects of rehabilitated pipe on the pullout behavior of joints in pipelines on which axial tensile load is acting, as part of the study on seismic improvement of pipelines with non-anti-seismic joints that are rehabilitated with a pipeline rehabilitation method. In the static and dynamic tensile tests conducted using sample pipes, rehabilitated pipe improved the preventive effect against joint pullout. In addition, this paper proposes to use the allowable strain of rehabilitated pipe as a performance index of anti-seismic capability to withstand strains that act in seismic motion.
This paper compares the buffeting response of a suspension bridge simulated in time-domain with full-scale measurement data. First, the buffeting and self-excited forces are formulated in terms of indicial functions (IFs) using convolution based linear unsteady and Volterra series based nonlinear unsteady wind models. Then, first and second-orders IFs are identified using experimental data. Subsequently, a turbulent wind field is simulated for full bridge using spectral theory. At last, a numerical example of a 3D suspension bridge model is presented. The time-history dynamic analysis results show that a good agreement in the buffeting response is obtained between numerical simulation results and measurement data. It also highlights the efficacy of proposed time-domain method to predict the buffeting response accurately.
In general, motion-induced vortex vibration is considered to be caused by the unification of separated vortex from leading edge and secondary vortex at trailing edge. However, the results of wind tunnel tests for the cross sections with side ratios of 1.18 reveal that motion-induced vortex in heaving mode might occur without the formation of secondary vortex at trailing edge. Therefore, in order to clarify the relation between secondary vortex at trailing edge and the generation of motion- induced vortex vibration, spring-supported and flow visualization tests for rectangular cross sections with side ratios of 0.50-6.0 were conducted. It was found that the stable shedding of secondary vortex at trailing edge is not necessary condition of the generation of motion-induced vortex vibration in heaving mode.
In this study, twin box girder is applied to the super long multi-span suspension bridges with center span length of 3000-meter to improve the flutter wind speed. Next, center stay cables and X-type rigid frames are attached to gain higher flutter wind speed. The flutter wind speed of twin box girder type is improved compared to that of single box girder type. Furthermore, by analyzing the flutter vibration characteristics of the bridge and applying appropriate measures, it is possible to obtain a higher flutter wind speed. It is also found that flutter wind speed does not depends on number of spans.
The purpose of this study is to elucidate the effect of variations in material properties of GFRP materials on the response performance of pedestrian bridges. First, the static loading test and the vibration test are performed on the actual GFRP pedestrian girder bridge assembled in the factory before completion, and the response performance of the bridge is evaluated. Then, the response analysis of the actual bridge was performed using the constructed finite element model. In addition, the performance of the bridge is statistically evaluated by conducting Monte Carlo simulation assuming the variation of material properties.
This study proposes a stiffness evaluation method for road bridge decks using the influence line obtained when vehicles traveling on each lane of the bridge as input data. First, running tests using a test truck were performed on a test bridge to estimate the conversion factors of the bridge weigh-in-motion method (BWIM). Then, the monitoring of the running vehicle loads using the BWIM for ordinary vehicles was carried out for 11 days, and the influence line of deck displacement was estimated based on the obtained vehicle specifications. Finally, the stiffness of the slab was evaluated by analyzing the results obtained from the tests and the numerical analyses. It was found that the current stiffness of the slab decreased as compared with the results at sound state.
The measurement of low-frequency sound is considerably affected by wind. We previously conducted wind tunnel experiments and field experiments, and confirmed that characteristic values of wind play a major role in evaluation of wind noizes. Here, we derive a wind noise estimation equation as a function of frequency, the mean wind velocity and the turbulence intensity of wind. A method is proposed for finding the necessary coefficients of the estimation equation through field measurements. Furthermore, field measurements of low-frequency sound a road bridge are conducted and the wind noise computed using the proposed estimation method and measured values are compared. As the consequence, we have verified that the proposed method is valid to esitimate wind noise in low-frequency sound measurement.
This study is intended to examine the traffic-induced low frequency sound radiated from a highway bridge in design stage by means of a three-dimensional bridge- vehicle interactive analysis and a boundary element method (BEM). The three- dimensional bridge-vehicle interactive analysis was adopted to estimate velocity responses of the bridge, and the BEM was used to simulate the propagation of the low frequency sound pressure level (SPL) around the bridge utilizing simulated velocity responses of the bridge. The influence of road surface roughness and hump at the expansion joint of the bridge to radiation characteristics of the low frequency sound is also discussed. This study also proposed a method for expressing the sound field around the bridge in the time domain.
Large amplitude vibration is observed at some railway bridges. Train axle loads cause resonances. To address this problem, the use of active mass damper is numerically studied. Unique characteristics of this problem are as follows. The stroke of the dampers is limited. The loading determined by the wheelbase combinations is non-stationary. Both double-passage and single-passage cases need to be considered. Pseudo-static displacement of the bridge exists and its effect at train entrance and exit needs to be considered. The frequency of the bridge changes over time due to environmental changes. A variable-gain feedback control is employed with design parameter identification through genetic algorithm. The active control is numerically shown to reduce the train-induced vibration.
Bridge girder ends were the major weak points against corrosion. Therefore, it is necessary to develop the anticorrosion technique for them. In this study, we focused on Cold Spray technique, which can form a metallic film, as a corrosion protection film-forming method. In this study, we applied the mixed particles of zinc particles and alumina particles to the corroded steel bridge girder ends in the Cold Spray method to verify the corrosion protection performance and field applicability. Cold Spray Corrosion protection technology was applied to the corroded steel bridge girder ends, and corrosion monitoring was performed to verify the effectiveness in a corrosive environment.
This study examined experimentally corrosion inhibition effect of temporary coating performed with bridge inspection through accelerated exposure tests. Because it is difficult to remove completely corrosion of steel substrates surface performed with bridge inspection, the temporary coating is carried out by spray painting without surface preparations of steel substrates. The corrosion inhibition effect of temporary coating is evaluated quantitatively by the variation of thickness of steel specimen before and after the accelerated exposure tests. As the result, it was confirmed that thickness reduction quantity of steel specimen coated temporarily was reduced more by approximately 50% in five years than that of steel specimen without temporary coating.
To solve the serious problem for durability of weathering steel bridges by the undesired corrosion, it is necessary to eliminate its cause or to apply the repair coating. The life expectancy of the repair coating depends on appropriate surface preparation and the reliable removal of rust containing salinity. In this study, two type methods were examined for actual weathering steel bridge in 2015. One of the repair coating method is Rc-I for weathering steel bridges ("washing method") having water washing process, and the others ("water wash less method") have new alternative process that is not washed with water. The investigation of three yers after repair coating showed that both repair coating film was confirmed to exhibit good corrosion resistance.
Cables covered with polyethylene used for cable-stayed bridges have high anti-corrosion performance, but it is difficult to grasp the condition of the internal wires when the polyethylene is damaged. Therefore, temperature and humidity inside the cable and steel pipe measured in order to clarify the behavior of temperature and humidity that is affected the cable corrosion when the polyethylene was damaged. As the result, it was clarified the difference in humidity behavior between steel pipe and cable, and grasped the trend of temperature and humidity inside the cable.
This research aimed to clarify the corrosion condition of the main cables used for over 50 years on an actual suspension bridge. The cables were disassembled into the galvanized steel wires and the corrosion condition of them was assessed by two methods: the corrosion evaluation criteria based on the exterior appearance; the rust composition analysis. As an evaluation result by the criteria, the corrosion condition was the more outside, the more corroded, and the wires around the centre of the cables were not corroded. In addition, from the relations with the exterior appearance and the rust composition, this study proposed new corrosion evaluation criteria. According to the evaluation results by the proposed corrosion evaluation criteria, the condition which includes zinc corrosion and steel corrosion was assessed accurately.
In order to use a steel bridge for a long period, attention must be paid to corrosion. Corrosion of steel bridges occurs in the presence of oxygen and water. Oxygen exists in the atmosphere, but there are various ways of water supply, and one of them is dew condensation. Dew condensation is a general water supply method in steel bridges, but there are few studies on dew condensation. Then, in this study, from the viewpoint of dew condensation which is one of corrosion factors of steel bridge, temperature and humidity of the object bridge and girder temperature were measured, and generation situation of dew condensation in the bridge was grasped. In addition, the simple evaluation of dew condensation environment of the object bridge was also carried out using the inverse distance weighting method.
Accurate evaluation of the corrosion environment of steel bridges for corrosion prevention is important. In the past, an evaluation method of dew condensation due to temperature and relative humidity was developed using a weather research and forecasting (WRF) numerical weather prediction technique. In this study, accuracy enhancement of WRF for corrosion environment evaluation is discussed to obtain accurate results. In Japan, WRF used United States Geological Survey-based land - use data, gave inaccurate results to a certain extent. In this paper, the land use data provided by the Geospatial Information Authority of Japan is used to improve the accuracy of the WRF model. Additionally, a temperature modification factor is proposed to obtain the actual girder temperature from the atmospheric temperature.
Corrosion induce loss of cross section and section stiffness. We usually repair this damage with high strength bolted steel patch plates. However, the repair work is often carried out under dead load and also conducted by one side depending on working space and the corrosion extent. In this study, the experiment and FEM analysis is carried out to confirm the effect of preload such as dead load on the mechanical behavior of one / both side repaired member. In result, Preload and eccentric bending moment of one-side repair decrease yield strength and load sharing ratio of patch plate after yield limit state. The load sharing ratio of patch plate can be calculated with beam theory considering eccentric bending moment and improved by constraint out-of-plane displacement.
This study carried out an analytical study to clarify the slippage and yielding limit states of high strength frictional bolted joints subjected to compressive force. The analytical model was constructed on the basis of past experiments in which compressive force was loaded, and parametric analysis was carried out by changing plate width, connected plate thickness, friction coefficient, and number of bolts and thickness of splice plate. The result clarified the sliding, yield limit and the buckling limit of the joint subjected to compressive force. In addition, the result also showed that there was little change of the slip coefficient of the multiple row joint under the compressive force.
From the point of view of rational asset management for the steel bridges, it is very important to evaluate slip resistance-keeping capacities on high strength bolted connections with corroded splice plates. Therefore, the tensile tests with corroded spliced plates were conducted in the past study. From the tensile tests, it has become clear that the slip resistance would be decreased with corrosion thinning of spliced plates. However, the causing factor of axial force decline, which are the cause of decline of slip resistance, haven't become clear in details. In this study, FE analysis of tensile tests with corroded splice plates had been conducted in order to clarify the mechanism of axial force decline in high strength bolted connections with corroded splice plates.
Recently the deterioration of RC slabs of the steel girder bridges has been increased. It is supposed that these updating is necessary in the future. The cast iron deck was developed as lightweight and highly fatigue resistant deck slab. The mechanical connections between these modules are inevitable because the cast iron deck is composed of multiple modules. On the other hand, shortening construction time is required for replacement RC slabs. We propose to use a high strength bolted tensile joint for the cast iron deck module connection. In this study, an experiment has been carried out for the specimens modeled as the cast iron deck module connection. It is confirmed that the mechanical behavior of this connection is clarified.
According to the revision of Japanese Specifications of Highway Bridges, it's possible that plastic resistance and ductility of members will be more effectively utilized depending on limit states of members in future. Ultimate limit state of high-strength frictional bolted joints should be determined considering the resistance and ductility to enhance resiliency of connected members. Authors have proposed the new ultimate limit state which is defined by bolt hole deformation by the bearing force of bolt and can secure safey margins of both resistance and ductility. In this study, numerical analysis was conducted to clarify the effect of various configurations on the bearing resistance and then the design bearing resistance was proposed with analytical and past experimental results.
If the thicknesses of connected plates in high strength bolted joint are different, filler plate is used to adjust the difference in thicknesses. The filler is extended in some cases to reduce the relative displacement between splice and connected plate. In Japanese design codes, the extended filler is usually adopted to bearing type bolted joint. Slip and after-slip behavior of the extended filler plate in frictional joint is not investigated. This study focuses on the extended filler. The behaviors are investigated by FEM analysis. This paper concludes that the influence of extension of filler in high strength bolted frictional joint is small to resistances such as slip load and yield load.
In the case that the fatigue crack face is contacted due to the stress condition, un-derestimation or overlook of the crack might happen in ultrasonic testing. To cope with such a crack closure problem, the nonlinear ultrasonic method is immensely promising. The contact and non-contact behaviors of crack faces generate super-and sub-harmonics arising from interactions with large amplitude incident waves. In this study, an attempt has been made to evaluate fatigue cracks in a structural components using ultrasonic waveforms traveling a long distance. Here, the ultra-sonic waves transmitted through the fatigue crack in a steel specimen were measured while changing the contact state of the crack face. The properties of the measured signals were investigated by comparing to numerical modeling results.
For large-scale steel structures such as orthotropic steel decks in highway bridges, nondestructive inspection of fatigue damages is indispensable for securing their safety. The present authors developed a new thermography NDT technique for crack detection, which is based on temperature gap appeared on the surface of structural members due to thermal insulation effect of the crack. In this paper, the feasibility of the developed technique for detection of the non-penetrating fatigue cracks is investigated. The results of verification experiments using slit specimens and fatigue crack specimens are shown. The influence of anti-corrosion coating on the developed inspection is also clarified by FEM numerical simulation.