We performed structural damage event evaluation using an evaluation model of concrete shear strength degradation of a multi-hinge structure which has a complicated damage process like a railway viaduct. In this evaluation, structural damage event analysis with push-over nonlinear analysis is carried out. Evaluation of shear strength degradation with curvature is performed. And we appraised the seismic damage loss of two different shear strength degradation methods (deformation angle and curvature) in the identical structure. As a result, we appraise the structural performance of a multi-hinge structure, considering shear strength degradation of beams and columns with curvature.

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This study evaluates surface roughness of a corroded steel angle member exposed to oceanic environments for 19.5 years. Three-dimensional surface roughness parameters are used on surface roughness components extracted from a multi-resolution analysis to identify a dominant scale. It is shown that the proposed analysis can characterize surface roughness peculiar to various corrosion environments including atmospheric, splash, tidal, and submerged zones. By several simulations of corroded surface with using normal probability field, the relationship between characteristics of variogram and roughness indexes are examined and the applicability of this simulation is discussed.

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In order to elucidate the mechanical behavior of steel bridge pier whose local buckling parts were corrected by heating and pressing, a series of experiments was conducted. It was confirmed that mechanical characteristics of the steel were unchanged by heating/pressing correction with or without water-cooling only if heating temperature was kept below A₁ transformation temperature. In the case that residual imperfection was larger than initial deflection and its mode was the same as buckling mode, the maximum load of the specimen after heating/pressing correction became lower comparing with that in the virgin situation. However, in the case that the mode of residual imperfection was intentionally inverted to buckling mode, the maximum load after heating/pressing correction was the same as that in the virgin situation.

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In steel bridge piers, weld defects induced by inappropriate fabrication have been considered as the origin of brittle fracture caused by earthquakes. In addition, increment of rigidity at beam-to-column connection due to reinforcement with bolted plate might lower load carrying capacity of steel bridge pier. In this study, for the purpose of examining the load carrying capacity, push-over analyses have been carried out. The models used in analyses are non-damaged model, damaged model which beam lower flange at beam-to-column connection is failed, and reinforced model which plate is set up using bearing type bolts at the damaged connection. Load carrying capacity of damaged model decreased about 10% compared with non-damaged model. This result indicates that weld defect induced at beam lower flange is not critical for the collapse of the steel bridge piers.

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Shot blasting is usually used for surface preparation for paint of steel members. The method is also used to improve fatigue strength of machine components such as gears or shafts. Fatigue tests were carried out on out-of-plane gusseted specimens in bending. The specimens were tested with or without the shot blasting. Surface residual stress was measured by X-ray diffraction analysis at surface of flat portion as well as weld toe of the shot-blasted specimens. It was found that residual stress at the weld toe, which is normally high in tension, was decreased or turned into compression due to the shot-blasting. The test results showed that the fatigue life of the shot-blasted specimens was longer, when the tests was carried out in stress ratio, R= -1.

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Fatigue test was carried out to investigate the fatigue behavior of fillet welded joints, such as single-sided, double-sided and cruciform joint, under plate bending. It is found that all fatigue cracks are initiated at the weld toe of each fillet welded joint and propagated in plate thickness and width direction. Fatigue crack propagation behavior under plate bending was explored, comparing the past results from fatigue test performed under tensile loading. As a result, it is figured out that the fatigue crack growth rate was decreasing considerably under bending for tensile loading from the relationship between crack depth and fatigue life. Therefore, the fillet welded joints under bending had long fatigue life for under tension. Additionally, 1mm method was used to predict the fatigue life of each fillet welded joint under bending.

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Initial condition measurement of static deformation behavior before its service start and vibration characteristics on completed bridge of U-shaped steel girder bridge, are dealt with in this paper. The 3-dimensional Finite Element Method is used to model this tested bridge. The deformation characteristics of shoes was measured and detailed modeling of this effects needs to consider. And the natural frequency characteristics of their modes are examined using the ERA (Eigensystem Realization Algorithm) method. Simulation analysis considering road surface irregularity and coupling effects between vehicle and bridge was done. The data of this analysis is utilized to monitor the change of deformation and vibration characteristics due to the degradation and damage of bridge.

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The deterioration of performance of steel structures comes from various reasons. One of main reasons of such deterioration is the corrosion of steel, and the development of a reasonable repair method is demanded. This paper presents the applicability of CFRP adhesion for the repair of corroded steel members. Steel beams with fictitious corrosion repaired by CFRP were tested under bending in order to assess the repair method of corroded steel. As a result, it was confirmed that the stress of corroded steel was improved by patching CFRP.

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In case of the repair of a superannuated riveted joint, three methods are considered: 1. replacement of the supperannuated rivets, 2. installing the bearing type of the bolts, and 3. installing the high strength bolts as the frictional joint. Using high strength frictional bolted connection is preferable method from the viewpoint of repair cost and easiness of repair works. However, the mechanical behavior of the riveted joint in which some rivets are replaced by the frictional bolted joint is not clear. The objective of this study is to investigate analytically the strength of the riveted connection replaced some rivets by the high strength bolts, and to discuss the applicability of such repaired riveted joint considering the number and the position of the replaced rivets. It is concluded from the analytical results that the strength of the repaired riveted connection by using high strength bolts is sufficient for a repairing method of superannuated riveted joints.

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Epoxy resin filler is usually applied to ensure the slip resistance and to protect further corrosion on the friction surfaces when corroded steel members were strengthened by additional plates with high strength bolts. In order to clarify the influence of epoxy resin filler on the strengthening, tensile tests of bolted connections with various thickness of resin layers were conducted. It was found that slip resistances of the bolted connections were somewhat higher than those of the connections without resin, even though thicker resin layer definitely caused reduction of bolt tension.

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In this study, it is proposed to use frictional connections by vises for the repair of bridge members, such as temporary joints in which corroded rivets or high strength bolts are replaced to new ones and for emergency repairs of members where fatigue cracks are detected. The tensile loading tests and the cyclic tensile loading tests are carried out to confirm the slip behavior of the frictional connections by vises. In the experiment, three types of specimens are prepared, a single frictional surface of vised joints, two frictional surfaces of vised joints and high strength frictional bolted connections. It is found that the vised frictional specimens have the same slip coefficient as that of the high strength bolted frictional specimens. However, it is necessary to investigate the appropriate value of installation torque for the vised frictional joints in case of the emergency repairs of bridge members.

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In this study, in order to analyze axle weights accurately, a method using time-frequency analysis was applied to detect axle position information from strain hitrory data with relatively long influence lines. The axle position information includes the number of axles, spacing of axles, and axle position at a moment. This method can improve accuracy of analysis results of axle weights by Weigh-In-Motion and reduce the number of strain sensors in a monitoring system. Furthermore, it can be adopted to analyze vehicle types or velocity. In this study, the method using time-frequecy analysis was demontarated for the case of orthotrapic steel deck system.

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It is important to estimate corrosion environment of steel bridges for a proper corrosion prevention and maintenance program. Sea salt particulate matter (SS-PM) plays a critical role in a corrosion process of steel bridges. Generated by wind on the ocean, it flies some distance over land and attached itself on the bridge surface. Although the generation and flyover of SS-PM have been observed intensively, adhesion of SS-PM on bridge surface is yet to be investicated both experimentally and numerically, as adhesion of SS-PM occurs in a highly non-uniform manner. The objective of this work is to simulate the behavior of SS-PM near a bridge using Lagrangeian type multi-phase flow analysis. The results show that the Lagrangian approach provides with a useful tool for the understandings of the adhesion behaviors, though many are still to be studied in physics and chemistry of adhesion.

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Recently, maintenance problems of the existing RC structure have been increasing, thus to evaluate durability and predict deterioration of them come into important. In this study, the rotary hammering test that could improve inspection accuracy and efficiency of conventional hammering test is introduced, and examined diagnostic capability by means of the acoustic analysis based on finite element method. From analytical results of the rotary hammering test for concrete specimen, it is figure out the difference of sound pressure shapes between wholesome model and defect model. In addition, it is confirmed that utility of the rotary hammering test, and verifies the fact that this test method is not influenced by individual performance.

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Reconstruction of the existing bridge is difficult because of the reduction of the budget of the central government finance by an economic long slump. It is important to be going to attempt making of the existing bridge long-lived with an appropriate of maintenance in the future. Therefore, it is necessary to develop the investigation method to be enforceable of the health evaluation of the deteriorated bridge in year of passing promptly and easily. The purpose of this paper is to clear static, dynamic characteristics of the existing two span composite girder bridge with shoe restriction by using the static, dynamic loading test results, and to examine what influence the deformation of the pier gives to these characteristics.

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A new type of cable supported bridge, the cable-stayed arch bridge, is proposed in this paper. This bridge is a combination of a steel cable-stayed bridge and an arch bridge using concrete-filled steel pipes as arch ribs. A cable-stayed arch bridge with a main-span of 300m was designed and its safety for breakage of structural members was checked by the performance based design method. Large deformation analysis was used to obtain sectional forces. The designed bridge satisfied the required safety condition. It was found by the ultimate strength analysis that the bridge collapsed when the arch ribs buckled in horizontal direction. Required steel amount of the cable-stayed arch bridge is significantly lower than that of the cable-stayed bridge.

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The equations of motion have been proposed to predict the horizontal girder response induced by pedestrians. The equations take into consideration the rate of pedestrian's horizontal force to pedestrian's weight, the pedestrian density, the rate of synchronized pedestrians, and the pedestrians' attitude to large vibration amplitude. This method is then applied to the two cable-supported bridges that have suffered the horizontal vibration. The predicted horizontal girder responses agree very well with measured girder responses of these bridges, which verify the prediction method.

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Thanks to the advancement of computer technology and finite element software, now it is not difficult to carry out three-dimensional finite element analysis of a bridge, using shell and solid elements, which can yield realistic structural behavior. However, there still remain tasks to overcome. For example, it is not very clear yet how to construct a good finite element model of a bridge. In the present study, a finite element mesh that yields little discretization error is investigated first. Using the mesh obtained through that investigation, the three-dimensional finite element analyses of steel I-girder bridges are conducted. Based on the numerical results, the roles of members in the bridges are discussed. It is found that some members play a role that is not assumed in design.

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A relatively good performance of timber joints with pre-tensioned bolts under static-cyclic loadings was previously reported. For a more reliable earthquake-resistance timber structure, however, their performance under seismic forces needs also to be well understood. In this study, seismic performances of pre-tensioned moment-resisting joints are examined through a series of shaking table tests. A part from this study, a single-degree-of-freedom oscillator model is developed to predict their seismic responses in which the joint stiffness is governed by a trilinear-skeleton hysteretic curve. Dynamic equilibrium equation of motion of the model is solved using step-by-step integration method with linear acceleration assumption and constant viscous damping coefficient. The test results show that damping ratio and dynamic stiffness (an equivalent stiffness of moment rotation relationship) of the pre-tensioned joints are much greater than those of the non-prestensioned joints. For small amplitude vibration, average damping ratio is 9.40% and 6.59%, respectively, for the pre-tensioned and non-pretensioned joints. Good agreement is found between the measurement and prediction, though less joint rotation is observed in the measurement after the occurrence of interlayer slip between the joint members. This reduced response is essentially related to additional damping due to clearance around fasteners in pre-drilled holes.

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In recent years various types of hybrid structures such as steel-plate-inserted glulam-beams are adopted for timber road bridges. Since glulams are materials with very low shear stiffness which is not always improved by the steel-plate insertion, it is very important to investigate elasto-plastic behaviors of the steel-glulam hybrid beams. In this study we try to experimentally and numerically investigate glulam beams and three types of steel-glulam hybrid beams with vertically inserted steel plates . We compare FEM analysis with experiment and discuss the influence of steel-plate insertion condition on shear stress.

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In this study, fatigue tests are done using two kinds of out-of-plane gusset welded joint specimen; a specimen without strengthening; GN, and a specimen with a glass fiber reinforced polymer (GFRP) pasted with an adhesive on the weld zone; GF. As a result of the experiments, S-N curves, photographs showing crack propagation, and the relation between crack propagation rate and the square root of half length of a crack are given. In addition, stress analyses of GN and GF are done using a finite element method to study the effect of the GFRP on reduction of stress at a weld toe of the round weld at the end of the gusset. Furthermore, the effect of the GFRP on fatigue crack propagation rate is discussed using fracture mechanics.

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A new method using glass fiber reinforced plastic (hereinafter called GFRP) to improve the fatigue strength of welded joints has been proposed, and the effect has been estimated analytically and experimentally for simple welded joints. However, the performance of GFRP was not confirmed for welded joints simulated real structure details. Therefore a series of fatigue tests and FEM analyses for the specimens reflected the details of ready-made bridges were carried out to inspect the applicability to bridges. As results, an equal effect of GFRP was identified as simple welded joints and the mechanism how GFRP improved the fatigue strength was clarified.

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Fatigue tests were carried out for fillet-welded specimens simulating fatigue cracks emanating from fillet weld root and propagating to deck plate of orthotropic steel deck. A newly developed fatigue testing machine for plate bending was used for the specimens of 300mm wide. Fatigue cracks initiated and propagated from root and propagated perpendicular to the applied stress to penetrate the deck plate in semielliptical shape. Failure occurred when crack from other side of deck plate of about 2 mm long joined the crack from the root. The test data was compared with previous test results of similar type. The one mm method was used to predict S-N curves of such details of different configurations. The test data was summarized as S-N diagram to be used for fatigue life predictions of existing orthotropic steel decks.

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In order to investigate the effect of the angle between principal stress direction and weld attachment on the fatigue behavior, crack initiation points and fatigue strengths have been examined by using the fatigue test results of out-of-plane attachments with various angles under uniaxial loading. As fatigue assessment methods, the nominal stress approach, the structural hot spot stress approach and the effective notch stress approach are used. It is possible to find fatigue crack initiation points by using the effective notch stress approach, regardless of the angle between principal stress direction and weld attachment. The effect of the angle between principal stress direction and weld attachment on the fatigue crack initiation life cannot be considered when the nominal stress approach and the structural hot spot stress approach are used. However, by using the effective notch stress approach, it is possible to consider the effect of the angle on the crack initiation life.

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This paper investigates fatigue performance of load carrying cruciform welded joint subjected to the combination of axial loading and out-of-plane bending. In the series of fatigue tests, applied out-of-plane bending stress is 20-25% of applied membrane stress. The results indicate that the influence of out-of-plane bending stress is small and it is also observed fatigue cracks from tip of incomplete penetration at compression side of out-of-plane bending leads fatigue failure. This paper also examines the effective notch stress approach for evaluating the fatigue test results obtained in this study. Then, simple method to evaluate the influence of out-of-plane bending stress is examined.

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The purpose of this study is to investigate the predicting equation for the punching shear capacity of RC slabs using fiber-reinforced lightweight concrete with steel or polypropylene fibers. The punching shear capacity of RC slabs with fibers increases and the structural behavior is improved by mixing fibers. Establishing the predicting equation, the shear resistance of fiber-reinforced concrete in the tension zone was defined with the post-cracking tensile strength. Furthermore, the depth of neutral axis and the size effect of RC slabs using fiber-reinforced concrete were considered including the test results in the literatures. In the present study, for convenience in calculation, the post-cracking tensile strength and the size effect were consequently adopted into the existing equation and the proposed equation was verified by comparing with the existing test results.

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To increase the shear strength of the beam, the she ar reinforcing effect of steel plate application to one side was evaluated.As the parameters, the embedded lengt h of an anchor and the number of anchors were selected. The results showed that the embedded leng th about 10 φ, is sufficient, and that the increase of shear strength is not in proportion to the incease of anchors.

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To evaluate the effect of reinforcing bar damage on ASR structures, the relationship between the damage ratio of reinforcing bars and physical properties of concrete, hoop ratio and bending radius were investigated. From the survey results, a correlation was found between reinforcing bar damage and bending radius. Therefore, a material testing was carried out, and the effect of bending method and bar type on the reinforcing bar damage was investigated. From the test results, it was found that the possibility of existing type reinforcing bar damage was very low if bars were bent in accordance with JIS standard.

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This paper presents an experimental study of the shear resisting mechanism of RC beams with stirrups. RC specimens with different concrete compressive strengths, yield strengths of stirrups, stirrup spacings and shear span to depth ratios were tested. Test results indicated that the beam and arch action provided a rational explanation of the shear resisting mechanism. The arch action was enhanced due to the increase of concrete strength and the stirrup inclusion, while the beam action was enlarged by only the latter. Additionally, the sum of the beam and arch contribution agreed with the ultimate shear strength. The modified truss model provided conservative predictions for both of the concrete and stirrup contribution.

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This paper presents results of experimental study on shear capacity of artificial lightweight reinforced concrete beams without shear reinforcement. 3D nonlinear computational simulation was used to investigate shear failure process and capacity of the beams. Nominal shear strengths of the sand lightweight (2150 kg/m³) and the semi-lightweight (2000 kg/m³) concrete beams, decreased by about 10% and 20% respectively compared to that of normal weight concrete beams. Using the same set of material models, it was possible to capture the brittle failure behavior and predict ultimate shear capacity of RC beams with reasonable accuracy. This study also confirmed the effectiveness of longitudinal reinforcement along the side of a beam's cross section.

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Comparing the results of a core test and the data of Alkali-Silica Reaction (ASR)-affected actual piers, applicability of an expansion test (JCI-DD2 Method) was investigated. According to the test results, a good correlation was found between the residual expansion of a core and future crack propagation in the pier. However, no good correlation was found between the initial expansion and existing cracks in the pier.

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A prestressed concrete bridge with corrugated steel webs is a structure with superior properties and cost effectiveness so that many bridges of this kind have been constructed up to now. In general, stud connections or embedded connections have been used for the joints between corrugated steel webs and concrete lower slab. However, care must be taken to the inverted construction of concrete and water proofing of joints when used. With a view to these problems, the validity of placing lower slab on the inner side of corrugated steel webs was confirmed and new joint structures were proposed in this study. In addition, punching shear tests were conducted to investigate the properties of shear slip at the joints.

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Lightweight concrete used in this study is concrete made by using artificial lightweight aggregate as coarse aggregate. Although the small unit weight of lightweight concrete compared with normal concrete makes lightweight concrete advantageous for various applications, lightweight concrete has not been widely used as part of composite structures. One of the challenges for researchers when trying to use lightweight concrete as part of composite structures is to determine the characteristics and behavior of shear connectors, which are a key element for the integration of steel and lightweight concrete.
This paper reports the results of various loading tests conducted to investigate the characteristics and behavior of shear connectors for steel-lightweight concrete composite girders under positive and negative bending.

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As the joint structure of steel-concrete hybrid truss bridge, various structural types have been proposed and put to practical use up to now. In this study, two kinds of joint structures with perfobond shear connector and welded headed studs have been proposed. And the loading test in half scale specimens of the joint structure has been carried out to clarify the stress transfer mechanism of the joint structure. As the result, it has been clarified that the design strength on the existing ultimate strength equation for the joint has been enough safety. Moreover, the 3-D finite element method has been conducted, and the mechanical characteristic has been examined. In this paper, it was indicated the stress transfer mechanism and the load carrying capacity of the joint structure.

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In recent years, hybrid rigid frame bridges have been researched for rationalization and improvement of seismic resistance of the middle support section, and constructed increasing in number. The hybrid rigid structure for railway bridges is demanded an early recovery of performance compared with the highway bridges in case of appearing any damages by a large-scale earthquake, because it is considerable difficult to install the detour. In this study, we target the hybrid rigid frame for railway bridges that has comparatively long span about 100m. The purpose is to examine the load capacity performance of anchor-beam structure to use for the rigid connection of steel-box-girder and RC pier. Elasto-plastic FE analysis is carried out. As a result, some characteristics of stress distribution, and stress transmission of the middle supporting connection is confirmed.

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The socket connection is a simple connection to connect the steel pier and the foundation. This structure enables the reduction of the construction space and short term completion, and is suitable for construction in the urban area because the footing and the anchor frame that exists in general connections become unnecessary. In this study, perfoboud strips are installed in the socket connection to improve the performance and the estimation method of ultimate strength about the socket connection based on the result of the past model experiment is proposed.

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CFT (Concrete Filled steel Tubular members) has attracted much attention because of its structural superiority, especially after the Hanshin -Awaji Earthquake. However, the increase of weight by filling with concrete inside is one of problem associated with CFT. Thus in this study, to reduce the self-weight of CFT, CFDT (Concrete Filled Double-skin steel Tubular members) and CFFT (Concrete-Filled FRP-steel Tubular members) are proposed particularly for higher bridge piers. It is shown by four points bending tests that CFDT has higher bending strength than CFT. But buckling of the outer steel tubes occurred. If the buckling can be effectively prevented, CFDT would have even higher bending strength and ductility. As for CFFT, it becomes clear that the circumferential constrain of outer sheet exhibits especially after the concrete reaches its fracture with dilation of filled concrete.

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The purpose of this study is to observe the effect of different parameters on the connection of steel box filled with concrete. The steel box is monolithically connected with steel beam, while a steel pile is inserted in the concrete. In order to develop the design method, effect of different parameters i.e. insertion length, material strength, box size, pile diameter and pile length were observed in the connection of steel box filled with concrete. After analysis, two types of failure mechanism were observed i.e. crushing of concrete and yielding of steel. Crushing of concrete dominant case takes place after the softening of concrete near the edge of pile. It was also observed that with the increase of concrete compressive strength the ultimate load of the connection varies non-linearly and with the increase of steel box size, ultimate capacity of the connection increases. Then it was found that by increasing the pile diameter the stress distribution around the pile increases, as a result, the ultimate load capacity of the connection increases. Then it was observed that for smaller pile length (outside of the steel box) shear force controls the failure but for longer pile moment controls the failure of the connection.

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There are many design and constructed examples of the steel-concrete tied arch bridge in EU countries where the tension stiffening effect of concrete is taken into account. In designing of steel tied arch bridge having RC slab, however, the conservative design method, that is non-composite design, has been accepted in Japan. But in near future in Japan too, it seems that the composite design for tied arch bridge will be adopted. However, the adequate concrete placing sequence of the concrete slabs in composite tied arch bridge is not clarified perfectly. This paper reports the result concerning the optimum concrete placing method in compcsite tied arch bridge.

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The use of CFRP sheets and plates of higher tensile strength than steel can be effective for strengthening a superannuated existing steel I girder with regard to improving its load carrying capacity. Experimentally investigated in this study is the strengthening effect of I shaped steel girder with high modulus CFRP strips through a bending test by using four girder specimens. The strengthening effect derived from the differences in the elastic modulus of CFRP plates are verified through the comparaison between the strengthening effects by the CFRP plates of the high tensile strength and the high elastic modulus. As a result, it is concluded that CFRP plates of high elastic modulus is better than CFRP plates of high tensile strength in improving the load carrying capacity of superannuated steel girders.

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Recently, many research reports have been published on the application of CFRP strips to repair and strengthening of steel members. CFRP strips often peel off from steel plates due to high shear stress, namely debonding shear stress, which is produced in the adhesive at the ends of CFRP strips. In this study, it is shown that the debonding shear stress is reduced by using a low elastic modulus adhesive around the ends of CFRP strips. Solving the differential equation regarding the stress of CFRP bonded steel plates with a low modulus adhesive around the ends of CFRP strips, the characteristics on the stress in steel plates and the debonding shear stress in the adhesive are clarified. The analytical results are confirmed by the tensile tests of steel plates with a low elastic modulus adhesive around the ends of CFRP strips.

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Fiber Reinforced Plastics (FRP) is expected to application as the material for the civil engineering structures. There are some research cases about the GFRP pultruded I-section beams less than 300mm in height. However, stiffness enhancement has been hoped for because of a low elastic modulus. In this study, it carried out the material strength test of I-section beam with 600mm in height that became the maximum in Japan, and it was clarified the material properties of GFRP that was anisotropy. In addition, it carried out the static flexural-share test of I-section beam, and it was clarified the failure behavior. From the material test, it was confirmed that the material strength characteristic of GFRP was anisotropy, and the main failure mode depended on the interfacial failure of the resin matrix. From the static flexural-share test, it was clarified that the ultimate state of GFRP beam is due to local buckling that occurs in the vicinity of loading points. In case of setting up the stiffeners, it could control local buckling, and ultimate capacity improves greatly.

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In this study, the real behavior is investigated by measuring the dead load responses at the time of concrete casting in the slab and the shrinkage of concrete. The girder of the measurement is an actual railway girder. The measured results of displacement, strain (stress) are compared with design calculations and FEM analysis. As for the measurement result; it was examined influence of a composition effect by concrete casting order, and of a bending effect by concrete shrinkage.

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In the hogging moment region of the continuous composite girder, cracks are caused by the tensile axial force acting on the RC slabs. Then, accurate evaluation method of the crack width of the RC slab is required to control the cracking behavior of the RC slab, and many researches dealt with this problem. In this research, the static tests of the simple-supported composite beams under the hogging moment were conducted to observe in detail the strain behavior of the reinforcement and the cracking behavior in the RC slab. As a result, the strain behavior of the longitudinal reinforcement and the cracking behavior of the slab are measured successfully, and the strain behavior of the reinforcement is discussed based on the experimental results.

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In the city, the long span and thin slab are demanded for the bridge. In this study, the composite slab is shown for the floor group of through truss bridges. Design technique to control concrete cracking of the composite slab is used for these bridges; the repeated-load examination that simulated a train moving load was performed, in the composite slabs tension, for examination of the durability. As a result, it was confirmed that outbreak and development of the big damage did not occur by durability.

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Recently, composite slabs have been widely used as highway bridge slabs. In the composite slab that authors developed, the structure to use both perfobond strip and stud connectors as shear connectors is adopted. However, there are a lot of unclarifications about the share mechanism of the horizontal shear force of two kinds of shear connectors. Therefore, the rationalization of the design is not attempted. This time, static bending tests of this kind of composite slab were carried out and three-dimensional FEM analysis that considered following was carried out. (1) Concrete material nonlinear characteristic after it cracks. (2) Contact interaction between steel and concrete. As a result of the analytical examination, it became clear as follows; (1) Using two kinds of shear connectors could make the load-carrying capacity of the composite slab improve. (2) The share ratio of the horizontal shear force of two kinds of shear connectors at the design load level was roughly obtained.

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A steel-FRP-concrete composite deck was developed for replacement of deteriorated slab. The composite deck is consisting of a FRP form holding steel rectangular pipe to stiffen the form when concrete is casted. The FRP form is created by infusion method wrapping steel pipes with glass fiber mat. In this study the structure of this composite deck was rationalized. To evaluate fatigue durability of the composite deck is the most important structural problem for highway bridges. Here, wheel running fatigue test on full-size specimens are carried out, to find out the influence of the truss reinforcing bars arranged between the steel tubes. The results and evaluation of these trusses are described in the paper. Also, the bottom plate and connection plate improved to do fieldwork easily into reasonable one are confined to have sufficient durability.

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Stress and displacement generated near a loading point on a multi layer slab have been conventionally estimated from deflection and stress resultant derived from the thin plate theory. To understand the behavior of the slab precisely on a local basis, a three-dimensional analysis is required. This study proposes a method to create clamping conditions approximately through harmonic analysis by placing dummy girders with high flexural rigidity at locations very close to simply-supported edges. A technique that is combined with the point matching method was developed and applied to the calculation of stress and displacement generated near the loading points and on the layer boundaries of a multi-layer slab with all edges clamped. This technique allows description of three-dimensional stress and displacement properties within the slab except near the dummy girders.

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In this paper, the ultimate bearing capacity and failure mechanism of cohesive frictional soils with shallow tunnels of various cross sections in plain strain condition are theoretically investigated. This problem corresponds to drain loadings and the internal tunnel pressure is set as zero. Not only circular but also ellipse, flat, horseshoe, rectangular and square tunnels are used as the shape of tunnels. The infinity loading, and the smooth and rough conditions for the interface between the loadings and soils are also considered. For a series of tunnel geometries and material properties, rigorous plasticity solutions for the ultimate bearing capacity are obtained by appling recently developed limit analysis methods at the University of Newcastle. The methods are based on both the limit theorems and finite elements, and lead to large nonlinear programming problems. The results are presented in the form of dimensionless stability charts for practical use and closely bracket the true ultimate bearing capacity for most cases.

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This study aims to assess the pile-group effect of pile spacing and pile parallel-spasing to the direction of loading in large displacement analytically. The analytical modeling used in this study is 2-D FEM model for the ground in consideration of the nonlinear characteristics. Major findings are as follows: (1) Pile-group effect occurs by forming the isolated single pile a line in a parallel direction. The influence becomes remarkable in less than 5 times of pile diameter. (2) In the loading direction, it occurs by forming the isolated single pile in more than 10 times of pile diameter. The lateral resistance of lead pile is larger than subsequent piles, and it's larger than the isolated single pile. (3) The pile-group effects depend on a pile-soil-pile interaction.

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