This study aims to establish the practical method for estimating the buckling temperature of continuous welded rails with efficiency based on lateral track irregularities measured by the track inspection cars. From the analytical results of FEM model with the virtual irregularities constituted of sine waves, the authors showed the possibility of estimating the buckling temperature by focusing on the maximum curvature of waves. Then, the authors prepared the restored waves of lateral track irregularities measured by the track inspection car and performed FEM analyses by use of the waves. As a result, the authors showed the efficient method for estimating the buckling temperature from measurement data of inspection car by used of the relative equations.

In frictional pretensioned bolted joints, the same specification is employed for contact faces in one joint in principle. Meanwhile, usage of different contact faces including the easy-processing faces might often provide labor-saving and accelerated works. However, in present study, slip coefficient in bolted joints using faces processed by grinder depends on the roughness of contact faces.

In this study, bolted joints including painted face with inorganic zinc rich paint and face processed by grinder using friction sims were made. Friction sims usually are used in drive unit for increasing the friction. And 21 bolted joint specimens were used in bolt pretention relaxation test and slip test. Finally, based on the results, the suitable slip coefficient in design is discussed.

The present paper aims at the development of temporary brackets used for erection of additional girders for bridge maintenance construction. A lightweight and highly rigid shape made of casting without welding joints is derived using topology optimization techniques. First, FEA (finite element analysis) of the current shape is performed, and topology analysis is performed using the result as a standard for comparison. After that, we use a three-dimensional sand mold additive manufacturing a test body, performance is evaluated through a full-scale loading test. From experimental results, the effectiveness of the optimal shape using the topology optimization technique is evaluated.

A reinforcement unit for conner of concrete structures previously developed by the authors was improved to make its structure simpler. To clarify force transfer characteristics between main reinforcement bar and the improved reinforcement unit, a uniaxial tensile test of the simplified specimens was conducted. It was founded, as a result, if the stiffness of the connection flat bar is insufficient, the force of the main reinforcement bar was not transfared to the angle steel, then the effective propagation rate decreased and the connection part was destructed.

In order to avoid brittle failures of welded box section steel members, cold pressbent rounded corner is effective. Considering effects of cold forming and strain aging, the use of SBHS, which has guaranteed higher toughness than conventional steels is suitable. In this study, material properties of cold press-bent SBHS400 were experimentally investigated. In addition, axial compression behavior as an unstiffened stub-column was examined both experimentally and analytically. As results, cold press-bent SBHS400 has enough toughness and the changes of mechanical properties are similar to those of conventional steels. The analysis results show that the difference in residual stress distribution largely affects on the load-carrying capacity of stub-columns.

Although B-live load is applied to bridge designs at present, considerable bridges had been designed with TL-20 in the previous design specifications. Most of these existing non-conformed bridges seem to be insufficient in load-carrying capacity under the current design code. In this study, a procedure for evaluating site-specific live load factors based on the actual traffic data for existing bridges is proposed. Two site-specific traffic data and three different girder bridges are employed to estimate live load factors for existing bridges as case study examples. The proposed method utilizes traffic-flow simulation and the generalized extreme-value distribution functions. The return period of the maximum bending moment for existing bridges is assigned to two intervals of the periodic bridge inspection.

An investigation on a series of cyclic loading tests and numerical analyses is presented using a new type of bracing system that is composed of both a tension and a compression member. This system is aimed at providing a stable lateral load-displacement(H-Δ) relation owing to an un-buckled tension member left even after the compression member buckles. As expected, the test results are such that a series of stable H-Δrelations have been obtained even after the compression member buckles. Then with the help of the numerical analysis method, the test results are extended to obtain stable axial force-axial displacement relations of each of the composed bracing members. Finally, the test results are discussed with regard to the low cycle fatigue of members.

In the 2011 Great East Japan Earthquake, it is said that small oil tanks installed at fishing ports were drifted by the tsunami, causing fires to the towns. In this study, we proposed two tsunami countermeasure and verified their performance using FEM analysis. In addition, a tsunami experiment was conducted to confirm the effectiveness of the tsunami countermeasure and the validity of the analysis.

Stainless steel rebar (SUS304-SD), a type of highly durable steel, differs from ordinary rebar in mechanical properties such as yield behavior and strain hardening. This paper presents an experimental investigation of the shear failure behavior of RC beams with stainless steel bars in concrete highway bridges. As a result, it was confirmed that even SUS304-SD, which has different mechanical properties from those of ordinary steel bars, does not differ from SD in its behavior and load sharing ratio in the range up to the yielding of shear reinforcement bars, and that the shear capacity evaluation formula in the highway bridge specifications, assuming fully elastoplastic bilinear behavior, can be applied.

In recent years, works to improve existing structures and strengthen their seismic resistance have increased. Pile construction in narrow spaces is constrained by the site and the construction process. Therefore, a construction method of soil-cement composite pile using a mechanical agitator was developed. The purpose of this study is to clarify the tensile resistance of the soil-cement composite pile with a reinforcing pile body. This paper briefly summarizes the construction method, then discusses the results of static load tests, and finally summarize the results of simulation by beam-soil spring model. The paper suggests the evaluation method of tensile resistance for the soil-cement composite pile.

For rational maintenance of corroded stiffeners on the supports, it is necessary to evaluate the residual load-carrying capacity. The evaluation of load-carrying capacity often employed finite element analysis or static loading tests. However, it is also necessary to evaluate the effect of the region and location of corrosion on the elastic buckling load. In this study, numerical analyses were conducted to estimate elastic buckling loads based on Euler buckling for beams with different sectional stiffnesses. The numerical analysis results were in good agreement with the results of the eigenvalue given by finite element analysis. Furthermore, numerical analysis was used to evaluate the effect of the region and location of the cross-sectional loss on the elastic buckling load.

The aims of this study are to propose the design bending moment equations and the minimum slab thickness. In the present specifications for highway bridges, the design bending moment of reinforced concrete slabs has been established among limited parameters such as the design concrete strength and the slab thickness. In this study, the design bending moments were considered with various slab thicknesses for rational slab design method from the elastic finite element analysis. Also, the minimum slab thickness was decided based on the bending strength of concrete considering a size-effect law. In the comparison to the specifications for highway bridges and the JSCE design code Part B, it was found that the design bending moment in the direction of distribution bar is necessary to increase.

This study evaluates applicability of full-field strain measurement by digital image correlation (DIC) to the data assimilation of FE model-based load capacity analysis of steel structural members. The verification was conducted by the tensile tests of steel plate member specimens with bolt joint boundary conditions. Validities of acquired DIC in-plane strain distributions were evaluated both in the initial structural condition and in the condition with local boundary condition changes by removing some bolts. Sensitive FE model parameters to in-plane strain data were extracted by the sensitivity analysis, and the posterior distributions of uncertain parameters of the steel plate specimen in each condition were appropriately estimated using the acquired DIC strain data.

In recent years, the development of sensing technology has resulted in the obtaining of large amounts of measurement data. The use of this data has become an important issue for further improving the efficiency of infrastructure maintenance. Assuming that more data will be obtained by the new techniques, this study proposed a method for estimation of the spatial distribution of the mass loss rate of steel bars based on the obtained spatial distribution of crack widths, and the evaluation of the residual capacity of RC structures and its reliability. For the estimation of spatial distribution, Gaussian process regression is used. We demonstrate the proposed method through numerical examples to evaluate limit state probability based on the spatial distribution of corrosion crack width of a pier.

In this study, with the aim of examining the cost reduction effects of each partial repainting and painting method, using a partial repainting coating model created based on the prediction of deterioration of the paint film and the prediction of the corrosion of steel, Life Cycle Cost and the corrosion of steel in the 50 years of service in different partial repainting methods were calculated by examination simulation. A rational partial repainting method was examined by quantitatively evaluating the relationship between them. As a result, a repainting method combining temporary coating and partial repainting, a method using the Rc₋I painting system, and a method of repainting when the rust area is 10% showed no significant increase in the amount of corrosion of steel, and the cost reduction effect was confirmed.

This study examined the applicability to assess the damage of bridge from the flooding by fluid pressure evaluated using basic fluid formulas. The damage of road bridges on the Kuma River in 2020 was estimated. As the result, the damage pattern of each bridge could be generally evaluated . The propriety of this assessment method for outflow was confirmed. The level of the hydrodynamic forces acting on the bridges was estimated. The horizontal load coefficients calculated based on the hydrodynamic forces were 0.1 to 0.6. Therefore, it is considered that it is possible to assess the risk of outflow from bridges crossing rivers which are dug into the ground depending on the design age and the conducted seismic reinforcement.

In recent years, steels with various high performance properties have been developed and applied to many steel structures. This study attempts to elucidate the ductile fracture behavior of high-strength steels at high stress triaxiality by FEM analysis based on experimental data for two types of steels (SBHS500 and SM570). The generality of a relationship between the displacement at element failure and the non-uniformity ratio (the ratio of the average stress triaxiality at the notch tip to that at the center of the specimen), which has been proposed for normal strength steels in previous studies, is clarified by applying the equation to high-strength steels. Furthermore, the application to steel structures was attempted using steel bridge piers as an example.

Four BP-A bearings for road bridges were investigated based on monotonous tests and design calculations with the purpose to study the ultimate capacity and damage behavior under the horizontal force. As the results, it was confirmed that horizontal resistance characteristics of BP-A bearings were dominated by the shear key, the stoppers of the upper shoe and the lower shoe. Ultimate capacity obtained from the tests were 2.74-4.54 times of the designed capacity. A simple method for estimating the ultimate capacity of BP-A bearings by using the ultimate capacity of the dominant members was also proposed.

BP-A bearing tracks girder deformation with the bearing plate contact surface. Although, there have been few studies on the effect of the corrosion degree on the behavior of the bearing and on the horizontal forces in the lower flange that cause fatigue cracks in the sole plate edge welds. In this study, the effects of different degrees of corrosion on the BP-A bearing contact surface on the bearing behavior and surrounding stresses were investigated. The results showed that the position of the center of rotation of the bearing varies according to the degree of corrosion, and the magnitude of the axial stress in the lower flange changes according to this behavior.

Some old RC structures were constructed by using round bars with very low reinforcement ratio. In this study, cyclic loading tests of RC rectangular columns, which modeled old existing dam gate piers, were conducted. From the test results, the cyclic behavior was clarified, and the influence of very low reinforcement ratio and the difference from deformed bars were evaluated. In addition, it was verified that a bond-slip model for round bar in 3 finite element analysis is applicable to simulate the tested specimens using very low reinforcement ratio.

The purpose of this study is to develop a new evaluation method for ductile crack initiation and propagation in steel piers with thick-walled sections. To this end, elasto-plastic cyclic analyses of unstiffened box-sectional steel piers are performed using a three-step two-parameter ductile fracture model that simulates crack initiation and propagation. In this study, the ductile fracture parameter is changed from the damage propagation energy to the displacement at element failure, and the N-VG model proposed by authors is employed. As a result, the newly proposed failure analysis procedure is possible to evaluate the ductile fracture more precisely than the conventional method.

Wide variety of joint-type buried pipes are used for urban lifeline facilities, and the characteristics of joints may change due to the effects of aging. If the deformation of joint pipes arranged at regular intervals during an earthquake can be easily calculated, the evaluation of new and existing joint pipes becomes more efficient. Therefore, in this study, a new method is proposed to estimate the characteristics of the joint as the equivalent rigidity so that the analytical solution of the beam supported by the distributed spring can be used for evaluation. Reasonable solutions are shown in this paper obtained by proposed equations.

Various damages to water tanks have been reported due to sloshing and bulging. In particular, bulging has just added to the latest guideline, so it is necessary to understand it as soon as possible. In this paper, we calculate the bulging natural frequencies by the micro-tremor measurement device being installed on the roof panel of the water tank. Furthermore, as they are compared with the results from accelerometers installed on the wall and from finite element analysis, we confirm whether bulging natural frequencies calculated by using this device are correct. We also examine the usefulness of this device. As a result, it is found that calculated bulging natural frequencies by each method were almost identical.

This paper experimentally investigates the effects of side-surface openings on the torsional flutter instability of a rectangular cylinder with a side ratio of B/D = 5, where B is the width and D is the height. The torsional one-degree-of-freedom (1DOF) free vibration tests and flow visualization tests were carried out on the rectangular cylinder with different-sized openings. The opening size is non-dimensionalized as the Opening-area Ratio (OR), which is the ratio of the total-openings area to the sidesurface area. Increasing OR stabilized the rectangular cylinder against the vortexinduced vibration and the torsional flutter and promoted the separated shear layer to reattach more upstream side of the cylinder surface. This research contributes to providing a method to stabilize the box girder against torsional flutter.

The objective of this research is to investigate the aerodynamic performance of the edge girder of a cable-stayed bridge as part of the structural system. Through wind tunnel tests on the full elastic bridge model, the vertical and torsional aerodynamic response of the girder was measured. The wind was set to attack the model perpendicularly, at the positive angle of attack of 2.1°, at the yawing angle of 10° and 20°. For these different conditions, the bridge showed the vertical vortex-induced vibration of different modes, while it showed the torsional vortexinduced vibration of the 1st symmetric mode. The amplitude of these vortex-induced vibrations was smaller than the allowable value. Meanwhile, no galloping and no torsional flutter occurred until their checking wind velocity. Additionally, in the boundary layer turbulent flow, the bridge showed the gust response, the amplitude of which was small.

This study investigates the galloping-suppressing effect of loose spacers, which are frequently used to prevent galloping in four-bundled conductors, and the difference in the galloping-suppressing effect due to the position of loose clamps of loose spacers. Field observations of real-scale four-bundled conductors have been carried out for 11 winter seasons. The observation results showed that loose spacers can reduce the maximum tension fluctuation caused by galloping and the occurrence frequency of galloping. When the wind directions during ice-accretion and galloping are the same, the one-sided loose spacer was found superior to the diagonal loose spacer. However, the one-sided loose spacer may induce large galloping when the wind directions during ice-accretion and galloping are opposite.

The effects of rail joints on the dynamic response of bridges have not been quantified. This study measured the displacement of steel railway bridges for more than 1000 cases of train passage. Time-frequency analysis of the response revealed that high-frequency components between 40Hz to 200Hz when wheels pass through rail joints and frequency components of 42Hz and 125Hz immediately after the passage were observed. The presence of rail joints increases the girder dynamic displacement response amplification by a maximum of about 0.02 and 0.08 for a girder with a span of 22.3m and 6.7m, respectively. The amplification tends to increase as the rail joint became larger and the position of the rail joint closer to the span center.

In order to quantify the dynamic characteristics of truss bridges under high speed train passege, this study analysed the modal contributions of truss bridge based on dynamic interaction analysis. The analyses revealed that the first global bending mode and global horizontal modes mainly contributed to the static response of the truss bridge. In addition, deflection modes and floor systems vibration modes are predominant to the dynamic response. The floor systems vibration modes have less contribution to 100m truss bridge because of its more rigid main members than 60m truss bridge.

This study aims to investigate the effectiveness of a Bayesian hypothesis-based Bayesian damage detection using sensors arrangement optimized by means of the effective independence (EFI) method. The feasibility of Bayesian anomaly detection is verified using vibration and damage experimental data on an actual steel plate girder bridge. The optimal sensor arrangement and Bayesian anomaly detection for the bridge are also investigated using finite element analysis. Observations demonstrated that it is possible to detect damage and to identify the damage location approximately even with optimally arranged three sensors. In addition, the EFI method was also useful in Bayesian anomaly detection.

The performance of Japanese high-speed railway bridges regarding train-induced deck acceleration specified in Eurocode, which is different from Japan, has not been sufficiently verified. This study conducts acceleration measurement of a slab track type PC box girder bridge in Japanese high-speed railway. The global and deck local modal characteristics are identified, and the maximum deck acceleration specified in the Eurocode is evaluated. As a result, the maximum deck acceleration of the bridge is much lower than the Eurocode limit value despite the resonance condition. Unlike previous reports for European bridges, the main deck vibration modes of the bridge are over 40 Hz, thus the deck local vibration did not affect the evaluation of deck acceleration.

Belt conveyor support structures are under corrosive conditions because of dust accumulation. To assess the structural condition, the use of Cross-Sectional vibration Mode (CSM) has been studied. CSM, which can be estimated even under the plant operation, has been shown to have sensitivity to damage to a member, but the quantitative evaluation of the damage is yet to do. In this paper, the minimum cross-sectional plate thickness, which determines the load-carrying capacity of the tension member, is estimated using a two-step method. By using machine learning in the first step and modifying the estimated value in the second step, the method can estimate the minimum cross-sectional plate thickness with high accuracy and stability.

A variable deck height continuous box-girder bridge is often built by its structural efficiency. When the aerodynamic stability of this kind of bridges is investigated by wind-tunnel test, a superposition method (strip theory) of results of different height cross sections is used to predict the response of the full bridge. However, past studies showed that the superposed result did not coincide with the full-model test result. In this study, a variable height box girder is simplified by a linearly changing height one and its vortex-induced vibration response is compared with the superposed response of different height cross sections. The result showed that large slope of the girder breaks the strip theory and an axial flow along the slope is attributed to the discrepancy.

A multi-span cable-stayed bridge is planned for the Osaka Wangan Expressway Western Extension. Because A-shaped steel pylons are more than 200 m high, wind-induced vibration is a concern. In particular, the main pylons are prone to out-of-plane vibration in the completed system because the out-of-plane direction of the main pylons are not supported by cables. So, we conducted wind tunnel tests using a three-dimensional elastic model of the A-type pylons to determine the cross-sectional shape of the pylons with high wind stability. In addition, based on the wind observation data at the bridge site, a reasonable fatigue verification method was studied.

In this paper, we proposed the constitutive equation with multi-axial stress components for H-shaped cross-section steel, which is simplified considering the applicability of the practical design. The axial material test of H-shaped crosssection steel with monotonic and cyclic loadings are conducted to determine its material parameters. The numerical analyses of the material tests and the truss panel test with H-shape cross-section bracing members using the constitutive equation could reproduce their experimental results.

There is no specific calculation example for designing the required bolts to connect the jack-up bearing stiffener and the web plate of the main girder. Then, regarding the specifications for highway bridges, there is also a way of thinking that adopt twice the reaction force. This study constructed a finite element model for a simple steel girder bridge. And the shear force generated in the bolt was compared with the design value. From analytical results, the shear force was less than 50% of the design value, adopting twice the reaction force in analytical model. Therefore, it is show that the number of bolts can be reduced, and the efficiency of the maintenance work will improve.

In recent years, the fatigue durability of steel plate concrete composite decks has been evaluated by the wheel trucking test in Japan. The composite decks are applied to continuous steel twin-girder bridges and U-shaped steel girder bridges. Slabs are played important roles as a structural element. In order to study the behaviors of the continuous composite girder with the composite deck, a static loading test for the mid-supporting point area specimen was conducted. Furthermore, threedimensional finite element analyses for the specimens were carried out to compare with the measured values of the static loading test, and to evaluate stress distribution of concrete and longitudinal re-bars.

In order to clarify the effect of horizontal stiffeners and to confirm the validity of the bolt force estimation formula proposed by the authors, an experiment was conducted on bolted flush end plate connections with and without horizontal stiffeners, and with varying lengths of the stiffeners. The experimental results showed that the stiffness and yield strength of the connections were greatly improved by the installation of horizontal stiffeners. It was also found that lengthening the horizontal ribs had little effect on the stiffness and yield strength improvement, but it did reduce the strain on the web plates. Finally, it was confirmed that proposed bolt force estimation equation gives a safe evaluation in comparison with the experimental results.

In this study, the mechanical behavior of steel ring restrainer (SRR) under cyclic loading and the effects of geometrical dimensions and steel grade were investigated experimentally and analytically, on the basis of previous studies under monotonic loading. FE models were constructed from the experimental results and extensive parametric analyses were performed. The results show that in addition to the superior deformation capability of the SRR, the envelope under cyclic loading are consistent with the curves under monotonic loading. The predicted values by the proposed hysteretic model are close with the experimental and analytical results, indicating that the accuracy of the hysteretic model of SRR is good.

Relaxation of high strength bolted joints causes large bolt pretension loss at an initial stage of relaxation. For this reason, the slip tests are carried out after sufficient bolt pretension loss. However, these characteristics by relaxation differ depending on the type of contact surfaces. In this study, we investigated characteristics of bolt pretension loss at an initial stage of relaxation by referring to past literatures about high strength bolted joints cosirdering difference of contact surface type; painting, rust, rough surface, sprayed surface and galvanization surface. From these results, we discussed the implementation period of slip tests in high strength bolted joints. We also discussed an axis force for calculating the slip coefficient.

The friction type bolted joints were designed by the number of bolts, the number of faying surfaces, bolt preload, and slip coefficient. However, some researchers report that the relaxation of bolt tension enhances the friction coefficient. Therefore, the slip resistance of friction type bolted joints should be influenced by these factors. In this study, tensile tests of friction type bolted joints were conducted to investigate the influence of the bolt load after tightening and before the test on the slip resistance. From obtained results, the slip resistance was increased by increasing the tightening bolt load. And the slip coefficient was increased by decreasing the bolt load before test.

In order to develop a new high-strength bolt that contributes to consideration for the environmental issues, the authors conducted FEM analysis and tensile test using prototype bolt to understand its fundamental mechanical properties. Some bolt head shape which has smaller volume than conventional one was compared and examined by analysis, and tensile test was performed to confirm that tensile strength of the prototype exceeds the design strength. The new bolt named CE high-strength bolt, can reduce the weight by about 10% while having the same mechanical performance quality compared with the torshear type high-strength bolt.

This study examines the possibility of fatigue crack detection using vibration data obtained from a sign pole in laboratory experiments. The fatigue cracks were introduced to the base of the pole by cyclic loading. Anomaly indicator proposed by Goi et al is applied to the acceleration measurement. The proposed method quantifies changes in modal properties of the pole by means of Bayesian hypothesis testing. Comparison with power spectrum density shows that the anomaly indicator detects fatigue cracks when its natural frequency decreased by more than 1% and when the total crack length exceeded 10% of the steel pipe circumference.

Many studies are investigated for the reduction of slip coefficients in highstrength bolted frictional joints with oversized holes and slotted holes. Almost of studies are focused on slotted holes with the slot parallel to the direction of the force. However, few studies are focused on short slotted holes, and slotted holes with the slot perpendicular to the direction of the force. Many of previous studies are focused on slip. On the other hand, after-slip behavior is unclear. In this study, we attempted to evaluate the effects of oversized holes and slotted holes at the serviceability limit state and ultimate limit state by FEA with hole shape and plate thickness as parameters.

Bolted girder connections resist the applied bending moment through the cooperation of flange and web resistances. The present study focuses on the cooperative slip behavior of high-strength frictional bolted connections in an Igirder. In the present study, FEA of various cross-sectional dimensions of the web splice, having various bolt arrangements of the web splice, and various number of bolts in the flange and web splices have been conducted to quantitatively evaluate the cooperative slip behavior of the girder connections. From obtained results, as the bolt spacing of the web splice increased and the number of bolt rows of the web splice decreased, the ratio of the frictional force to the design slip resistance of the web increased.

It has been clarified that the stresses in the carbon fiber on the closer side to the steel plate tend to be higher when two steel plates are bonded together with multiple carbon fibers. This tendency might occur in corroded high-strength bolt friction joints retrofitted by the patch plates. In this study, finite element analysis and tensile tests were conducted on a joint with the splice and patch plates, focusing on the axial force on the splice and patch plates. The results of the finite element analysis revealed that the axial force sharing on the splice plate was about 10% higher than that calculated from the ratio of the cross -sectional area of the splice and patch plates. Tensile test results also showed the same tendency as FE results.

Patch plate repair and reinforcement using high-strength bolted frictional joint is used as a repair method for corrosion. There are not many study cases conducted on load sharing of girders subjected to bending. In this study, full-scale experiments of I-girder repaired the lower flange subjected to bending were conducted to clarify the effects of the bolt arrangement, thickness of the patch plates, and the number of the patch plate on the load sharing of patch plates and the repaired lower flange plate. To obtain the repair effect, it is desirable that the thickness difference between the patch plate and the lower flange is small and using two plates. In addition, the bolt arrangement should be evenly distributed and densely in the section where the load is transferred to the patch plate.

Rivet heads, projecting parts of riveted joints, are likely corroded, and the corrosion damage affects the mechanical behaviour. However, since the influence has not been clarified and ultimate resistance formulas of the intact and corroded joints have not been proposed, it is difficult to evaluate th e remaining resistances of existing joints. As a basic study to address these challenges, herein, tensile tests of coupon riveted joint cut off from an existing girder bridge were conducted to investigate influences of the corrosion extent of rivet heads with artificia l corrosion damage on the mechanical behaviour. The obtained results indicate that rivet head and thread corrosion have little influence on the ultimate resistance within the loss of rivet thread less than 30% of splice plate thickness.

There are many historical steel bridges with riveted joints, but damaged riveted joints is often repaired by replacing rivet with high-strength bolt. The reason is that the number of rivet casting engineers has decreased and application technique has not been passed on. The method of replacing damaged rivets with new rivets is effective in terms of workability and structural mechanics, and the rivet casting unit using high-frequency induction heating that can be used on site has been developed. In particular, the technical information necessary for riveting, which has not been recorded in conventional construction methods, was extracted through experiments, and the developed rivet casting technique was evaluated and verified.

As to a crack propagation analysis method proposed in JSSC Fatigue Design Recommendations for Steel Structures, there have not been many comparative studies on its applicability to crack behavior in out-of-plane gusset joints. In this paper, beach mark test results for 29 cracks obtained by fatigue tests of full -scale out-of-plane gusset joint specimens were compared with the calculated results by the JSSC method, and the stress intensity factor, K-values, were also compared between the calculated results and the finite element analysis results obtained by crack models. Estimation accuracy by the JSSC method was discussed regarding the crack depth, the growth rate of semi-elliptical cracks, and the K-values.

Fatigue cracks have been observed from welded joints of end diaphragms at steel railway troughgirder bridges due to vertical movement behavior at their supports that is not expected during the design phase. Since this movement behavior is complicated and varies on each bridge depending on the damage around the support, effective retrofitting methods against the crack have not been established yet. In this study, the influence of the vertical movement tendency at the bridge supports on the crack initiation location and crack propagation behavior at the end diaphragm was investigated through numerical simulation. The result indicated that the relative displacement at the bedplate affected the crack initiation location and crack propagation path, and that the stress intensity factor tended to gradually decrease after propagating a certain length.