Cable corrosion significantly decreases the ultimate and fatigue strength of cable-stayed bridges, which was parametrically studied with three different span lengths and different corrosion levels. The ultimate strength of the healthy bridge models was about 2.5 of the design loads, which satisfied the required safety of 1.7. Whereas, the ultimate strength lowered by about 25% as the loss of cross-sectional area increased due to corrosion. The elongation also decreases due to corrosion. The ultimate strength was found to sharply drop when the elongation became 1.0%. The fatigue strength of stays was studied taking a 500kN heavy lorry as the representative load. The fatigue strength sharply lowers as corrosion progresses and the severely corrode anchor cable becomes less than 4% of the healthy one.
Automatic welding robots cannot be applied to welding horizontal stiffeners to the web panel of curved steel box girder bridges due to the manufacturing cost increase. Elimination or reduction of the number of horizontal stiffeners without increasing the web thickness is desirable. In the present study, the influence of the horizontal stiffeners on the ultimate capacity and the collapse process were clarified by FE analysis considering the design sectional forces. From the obtained results, it was concluded that, even if the horizontal stiffeners are eliminated, the ultimate capacity decrease is little since the compression flange of box girders restrains bending buckling of the web panel.
Bridges are composed by many structural members which interact with each other to resist against various load combinations. In the present study, full-scale FE analyses have been conducted for a steel I-girder bridge system with corrosion damages which have been repaired. The analysis considered, the structural system behavior, varying the repaired areas. From the analytical results, it was found that, compared to the method in which the damaged portion is completely repaired, the amount of repair can be reduced by considering the bridge system behavior and partially repair both the damaged and the adjacent intact girders.
The strain-based seismic verification method (SBSVM) is proved to be one of the most reliable design methods for steel bridge structures. In order to make the method applicable to a variety of complex bridge structures, powerful numerical analysis tools such as elastic-plastic large deflection static/dynamic analyses are needed. The initial lateral load method (ILLM) developed by the authors is found to meet the requirements. A full procedure of SBSVM with ILLM was presented with the use of the test results of steel large scale double arch-rib model structures in the previous paper. In this paper one of the original arch-rib models is modified to upgrade its seismic performance with BRBs, and the effectiveness is verified by the proposed SBSVM with ILLM.
When using the launching erection method of steel bridges, the stability verification method of web plate buckling relative to the patch loading received from a launching apparatus, horizontal and vertical stiffeners are generally added to the web plates to ensure a safety factor. In this study, the reinforcement effect of these stiffeners was analyzed using standard stability verification method such as DASt012 and the Japan Society of Civil Engineers' Erection Design Guidelines. In addition, focusing on variation of load width, we studied the difference in reinforcement quantity required in each stability verification method. We clarified the role of stiffeners and the factors that reduce the difference in the reinforcement quantity by increasing the load width.
The purpose of this study is to develop a method for stably and rationally evaluating the load carrying capacity of steel I-girders subjected to shear, including corroded steel I-girders. In this paper, as a basic study, the shear load carrying capacity of the steel I-girders are investigated by FEM analysis, considering the anchoring effect of the web corner area. The FEM analysis shows that web corner area affects the maximum shear strength and the tension field action.
This paper introduces an approach to the realization of an ICT-based bridge remote monitoring system which enables real-time monitoring and control for unexpected heavy loads such as big earthquake and strong typhoon. In this paper, the integrated bridge remote monitoring system called the “Intelligent Bridge” consists of a stand-alone monitoring system (SMS) and a web-based internet monitoring system (IMS) for bridge maintenance but also its application to para-stressing bridge system as an intelligent structure. For the purpose of verifying its validity to actual bridge structure, an attempt is made to study the possibility of controlling the actual structural performance by adjusting the cable forces on a 2-span continuous cable-stayed bridge model.
This paper aims to ﬁnd out the optimum conﬁguration of a fundamental mod-ule which can be assembled into the temporary bridge to secure the traﬃc lifeline rapidly, when the natural disaster ocurries. After veriﬁcation that the optimum conﬁguration of periodic structure becomes also periodic, the opti-mum conﬁguration of simply supported beam isolated from 3-span continuous beam is searched as a fundamental module. The parametric analysis with com-bination of load position and support position are carried out, and two types of prototype can be proposed. Moreover, the optimum conﬁguration of cantilever bridge is also investigated with relation to the analytical domain and support conditions, and the analogy with Forth railway bridge is recognized.
In this paper, the fatigue durability of cable members in road bridges against live loads is discussed based on the stress amplitude calculated from the actual design data. First, the fatigue effect caused by 100-years live loads was calculated and the stress amplitude by L live loads equivalent to the fatigue effect was obtained using numerical simulation and actual axle load distribution. Then the safety factor of fatigue durability was examined using the design data base. Finally, it was found that the safety factor for the stress amplitude due to the live loads of cable members designed so far varies depending on the type of bridge and each cable.
To reduce the dynamic response of high-speed railway (HSR) resonant bridges under train passages, additional support(s) reinforcement of adding new support(s) on the spans is put into practice. In this study, the effect of additional support reinforcement with different positions between the both sides of a girder, which has not been clarified, and a simple evaluation method using span shortening amount were numerically investigated. As a result, for a HSP bridge to which the reinforcement is planned, the effects of asymmetry supports on the maximum displacement are small. Therefore, the effect of asymmetrical additional supports in this study can be evaluated by the result of symmetry one with the same span shortening amount, which is the total of the additional support positions.
The mechanical properties of both ordinary concrete and less binder concrete are examined in terms of uni-axial compression, shear and cyclic compression under tri-axial condition. The uni-axial compressive strength decreased with decrease of mortar volume. Decrease of shear resistance was not proportional to decrease of mortar. However, cohension with assumption of 35degree of internal friction was clearly affected by mortar volume. The strain distribution suggested that fracture of concrete started from upper to lower. Mohr's circles of the materials on the way to segmentation implied that the mechanical properties of both concrete and gravels can be estimated with single method. According to these experimental facts, the mechanism of segmentation of bridge deck was described.
Lifespan-extending technologies have been developed and put into practice for the purpose of inhibiting the deterioration of aged infrastructures. It is important to examine and evaluate the effects of such technologies, but in most cases, it is assumed that such technologies will remain effective forever. However, in the case of actual infrastructures, we cannot deny the possibility that the effects of them will decline with time. In detail, the effect of such technologies is evaluated with a change in deterioration hazard rate through the adoption, and it is assumed that the change can be represented by an effect function to formulate a dynamic deterioration hazard model. In addition, the authors confirm the effectiveness of the proposed method by applying it to a case of the waterproof layer of RC slabs.
Resilience assessment methods, performance indicators and recovery models used in the resilience assessment of road bridges and road networks were reviewed. Vulnerability analysis of road bridges under multiple hazards plays a key role in the resilience assessment of road networks. Selection of a performance indicator suitable for the assessment purpose and its normalization, and easiness to measure are also needed. Furthermore, post-hazard recovery models based on surveys on estimated time required to remove traffic closure and traffic partial restriction are important.
As one of countermeasures to realize viaducts superior in the Anti-Catastrophe, Collapse Direction Control Devise (CDC devise) has been proposed. The devise is used to control directions of the final collapse of viaducts to designated ways. In this paper, we propose a method for evaluating quantitative effects of the countermeasure of the devise based on a multitude of dynamic analyses. By the method, it becomes possible simply and quantitatively to evaluate effects in proportion to strength of the devises and to determine specifications of the devises to produce designated effects. Furthermore, in this paper, it is verified that the devise becomes more effective in proportion to stiffness and toughness of the devise and in inverse proportion to the distance between a pillar and the devise.
In this study, regarding the culvert damage caused by liquefaction during an earthquake, the degree of deformation that affects road function was clarified from the investigation and analysis of the damage cases. In the reproduction analysis of culvert displacement by a practical static analysis method, it was difficult to estimate the displacement that affects the road function because of a lack of dynamic influence. Furthermore, in order to clarify the effects of differences in ground and structural conditions displacement counting on seismic motion, model experiments were conducted resulting in confirming influence of liquefied layer thickness and shapes of culvert to display without.
Low cycle fatigue is a failure mode which is possibly caused by random large strains such as seismic motion. To examine the effects, this study elaborated crack propagation behavior in steel under random amplitude loading. Firstly, study on crack growth rate under constant amplitude conditions was conducted to obtain basic characteristics. Next, several patterns of random amplitude loading were applied. It is discovered that crack growth accelerated when amplitude decreased from high to low levels at tensile portions, compared to that in constant amplitude conditions. Prediction model was constructed with establishing relationship between cyclic J-integral range and crack growth rate and confirmed to give good estimation.
The long-term vibration monitoring of a steel girder bridge in the cold region was performed to investigate the temperature dependency on the dynamic characteristics of the bridge structure. The predominant frequency varied depending on the daily and seasonal fluctuation of the bridge temperature. A FE model with different elastic modulus based on each assumed temperature gave the natural vibration frequencies analytically. These natural frequencies have the same tendency with the measured result that means the main cause of the variation of the predominant frequency is the thermal dependencies of the elastic modulus of the structural members.
Prestressed concrete (PC) bridges account for about 44% of all bridges in Japan, and damage of PC tendons caused by defective grouting has been reported. In order to inspect, repair and maintain the PC bridge efficiently, it is necessary to develop a monitoring technology that can quantitatively and simply evaluate the integrity. This study examines changes in bridge performance and modal parameters of PC box girders due to progressive loading, and defective grouting and failures in PC tendons through the experiment. Static loading test showed that local cracks were dominated around the location of defective grouting and failure of PC tendons. A moderate correlation was observed between the energy-based bending performance and the natural frequency of 1st and 2nd bending modes.
In order to investigate the relationship between mechanical damage propagation and natural frequency change, a multi-stage loading test was conducted on two RC beams, one without a defect and the other with a defect in the center of the brace. Differences in damage propagation and the associated load bearing mechanism, mainly due to the concrete strength and the presence of notches, affected the load deflection history curves and the rate of decrease in natural frequencies for both specimens. Loading up to about 64% of the final load reduced the flexural stiffness with respect to dynamic behavior by 10% and the static unloading stiffness by 50%.
In general, motion-induced vortex vibration is considered to be caused by the unification of the separated vortex from leading edge and the secondary vortex at trailing edge. However, the results of wind tunnel tests for rectangular cylinders have revealed that the secondary vortex at trailing edge is not necessary for the generation of motion-induced vortex vibration. In this study, two kinds of cross sections where the secondary vortex at trailing edge is considered less likely to occur were selected as the target cross sections. Wind tunnel tests were conducted in order to give a further explanation of the effect of secondary vortex at trailing edge on the motion-induced vortex vibration at the wind velocity region where larger response amplitude occurs. As a result, the secondary vortex at trailing edge is not necessary not only for the onset of the motion-induced vortex vibration, but also at wind velocities where larger response amplitude occurs.
In this study, equations were developed to calculate the maximum swing angle of a jumper device in multi-conductor transmission lines owing to strong winds. A jumper device is used to maintain an insulation distance between the overhead transmission lines and the steel towers. The maximum swing angle of the jumper device under fluctuating winds was evaluated using the mean value, standard deviation, and peak factor of the swing angle. Theoretical solutions were derived from the equation of motion corresponding to the swing angle in a simplified structural model. The values obtained using the proposed equations were in good agreement with the results of the time-history analysis.
When the maximum operating speed of the Shinkansen is further increased, there is a possibility that noise and vibration propagating to the surroundings increase. In this study, we focused on the floating slab track with the anti-vibration components made of urethane as a countermeasure against ground vibration. We carried out the vibration test for full-scale track model and confirmed that the floating slab track showed high reduction effect for ground vibration. Furthermore, the ground was modeled into multiple patterns based on the geological data in a Shinkansen section, and the scope of application of the floating slab track in high-speed rail was examined by vehicle running analysis and ground vibration analysis.
Many pedestrian overpasses had been constructed based on the standard design and most of such bridges have been in service for over 50 years. These bridges often have corrosion damages at invisible members. Therefore, an efficient damage detection method as the structural health monitoring needs to be developed. In this study, a detailed finite element model was constructed to reproduce the bridge analytically and its vibration characteristics were compared to the measurement results. Furthermore, we investigated the effect of corrosion damage on the modal amplitude of the deck by using a finite element model. As a result of this investigation, it is basically possible to identify the damage location of the deck which by focused modal amplitude ratios of damaged conditions.
In the case of measurement of bolt axial force, we carry out calibration tests to calculate the conversion rate. However, characteristics of the conversion rate is not clarified. In this study, calibration tests are carried out on high strength bolts. Then, we investigated a lot of conversion rate by literature search. From these results, we discussed the conversion rate at calibration tests. Furthermore, a new method of calibration test was proposed.
This study focuses on bolt shank shear behavior of high strength bolted frictional joint after slip occurs. Successive bolt shank shear failure occurs from end to center of connected surface in long joint. The behavior is known as “unbuttoning.” However, the relationship between the unbuttoning and dimensions of the joint is not cleared well. In this study, FEM analysis had been executed to clear the relationship. The analysis cleared the bolt shank shear behavior before the joint reaches ultimate state. With the relationship between bolt shank shear behavior and yield and ultimate mode, the bolt shank shear behaviors in yield and ultimate state are discussed focused on the dimensions of joint.
According to the Japanese Specifications for Highway Bridges, in high strength bolted frictional joints, verifications of the resistances in after-slip behavior are required. In bearing type joints, a filler plate is extended beyond splice plates to connect the filler to a member by additional bolts (tight type filler), but there're few examples of high strength bolted frictional joints with it. In this study, effects by tight type filler in serviceability limit state and ultimate limit state of high strength bolted frictional joints are quantitatively examined by FEM analysis. As a result, tight type filler is effective in slip strength and shear strength of bolts, but there's a risk to deterioration of yield strength and breaking strength of connected plate.
When tensile type bolted joints are used in bridge structures, these joints have multiple bolt rows to resist a large sectional force. However, it is known that strength of tensile type bolted joints with multiple bolt rows are less than the strength for the number of bolts. This study focuses on a stiffener to improve the strength of tensile type joint with multiple bolt rows, and conducted these joints' experiment and FE analysis. The one of the obtained results is that the set of stiffeners is effective in getting the joint proof strength and the joint yield strength for the number of bolts. Additionally, installing the stiffener can improve the strength with less weight rather than increasing the joint flange thickness in tensile joints with multiple bolt rows.
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 device and replacing the corrosion damaged portion of the girder with a new member. Previous research has revealed that the web bypass method, in which the bypass device is bolted to the web, is superior in workability and stress transmission. In this study, we focused on the replacement of lower splice plate, analyzed it using the steel I girder shape and the shape of the web bypass device as parameters, and examines the applicable range of the web bypass method and the appropriate geometrical configuration of the web bypass device.
The cast iron deck module is a lightweight deck slab with excellent fatigue resistance. High-strength bolt friction joints are used to join cast iron deck modules and main steel girders. In addition, the high strength bolt friction joints between the cast iron deck module and the main steel girder have to be considered because the ribs of the cast iron deck module have a taper of 1°. In this study, we prepared an experimental specimen of a composite structure of a cast iron deck and a main steel girder, and conducted a horizontal loading test and FEM analysis. As a result, the sliding behavior between the cast iron deck and the main girder was clarified.
In order to improve durability of corrosion, previous studies reported that countersunk head bolts can be applied to high strength bolted friction grip joints. The surface treatment of the countersunk hole is specified to be inorganic zinc rich paint, if blasting of countersunk hole can be omitted in the construction site, the workability will improve. In this research, slipping test was carried out to evaluate the effect of surface treatment without blasting of countersunk hole on slip strength of friction grip joints with high strength countersunk head bolts. As a result, the effect of surface treatment of countersunk hole on slip strength is very small.
The authors have developed a new type of high strength single-sided construction bolt for frictional joints that can be fastened from one side at low cost and has excellent workability. For the purpose of collecting basic data for examining the applicability to steel structures, slip test and U-rib steel loading test of single side bolted friction joints using new type single-sided construction bolts were conducted. As a result, slip coefficient of single side bolted friction joints using new type single-sided construction bolts is about 0.44 to 0.51 about 30% to 40% lower than the hight strength bolt, because the contact pressure between members is lower than the bolt axial force.
The purpose of this study is to evaluate the stress introduced in steel plate with asymmetric defects repaired by patch plates with high-strength bolts. First, to investigate the tendency of stress in the thickness-reduced section, finite element analysis was conducted. From analysis results, the stress introduced in defect repaired by patch plates does not correspond with the one calculated by the composite theory of defected part and patch plates. Then, a simple calculation method of stress introduced in steel plate with asymmetric defects repaired by patch plates was proposed using the frame structure analysis. Finally, the range of application of the simple calculation method was discussed in comparison with the result of finite element analysis.
In this study, as a fundamental study of patch plate repair method by the mixed joint of adhesive and high-strength bolt friction joints, uniaxial tensile tests of de-fective steel plate repaired by the proposed method was carried out. In the proposed method, the high-strength bolt friction joints are provided between adhesive joints in the patch end and one near the defective part. As a result of the tensile tests, it was found that the adhesive joints can distribute the stress on the main plate to patch plates. Additionally, it was clarified that the load distribution ratio of adhe-sive and high-strength bolted joints. In addition, the simple estimation method of the load distribution of each joint was proposed.
Recently, the demands of flush endplate connections have been increased in the field of bridge structures. However, no estimation-methods are proposed of the bolt axial force in such connections. This study proposes a new estimation method of the bolt axial force in flush endplate connections by FE analysis. Firstly, prying force coefficient and joint stiffness formulas are derived from the analysis of joint elements which can simulate the bolt force increment of flush endplate connections. Secondly, formulas for acting force in lower flange, horizontal stiffener and web are also obtained from girder analysis with a lower flange that has the low-Young's-modulus-region. Finally, the new estimation method for a bolt axial force is established by these proposed formulas.
Recently, infrastructure construction has drawn up an inconvenience that affects the community which is required to minimize as much as possible. To achieve the results, the construction of temporary members must be done quickly. The double end plate connection utilized with high strength bolted tensile joint is considered. The past experiment has confirmed that double end plate connection using high strength bolted can apply to temporary bridge main girder connection with the height from 900mm up to 1,500mm. However, studies for mechanical behavior in low height girders are still unclear. In this study, we have clarified the load transferring mechanism of this connection joint of uniaxial loading member with low height girder by using the analytical results.
The main girders in a steel I girder bridge are connected with the slab, the sway bracing and the cross frame behaving together as a system. Therefore, if a single part of one main girder is corroded, the remaining healthy main girders are supposed to compensate it. In this study, the bridge loading capacity was evaluated using an FEM model of the bridge system assuming some or all girders girders is corroded. As result, it was observed that in case some girders in a multi-girder bridge system is corroded, some of the remaining healthy main girders compensate it, confirming the bridge system redundancy.
This paper deals with durability of aluminum alloy members with fastners using diffrerent surface treatments. Site survey of galvanic corrosion of bridge railings with stainless steel fastners in Okinawa was first carried out. Following the survey results galvanic corrosion exposure tests of aluminum alloy members of railings using different surface treatments of fastners were performed for 5 years at Miyakojima atmospheric exposure test field in Okinawa. Two types of atmospheric exposure conditions, direct exposure and under-eave exposure, were applied. It was found that a zinc flake coating treatment (GEOMET) for stainless steel fastners was the most effective means for inhibiting galvanic corrosion in aluminum alloy members in highly corrosive environmtnts.
In recent years, the number of steel bridges that have been in service for a long time is increasing. Corrosion is one of the causes of deterioration of steel bridges, and it is important to efficiently maintain and manage the corroded steel bridges. This study focused on dew condensation, one of the causes of corrosion. In order to properly understand the occurrence of corrosion due to condensation, the meteorological data and the occurrence of dew condensation were predicted using inverse distance weighting method (IDW) at any point. IDW only considers the distance, not elevation difference. Therefore, large errors occurred when predicting bridges in the mountains. Then, the evaluation was performed by the IDW using a modified formula considering the elevation difference.
This paper presents the temperature variation of steel structures with different colors subjected to solar radiation by means of experiments. Steel plate specimens of standard size with different colors wereexposed to sunlight to measuretemperaturechangesover the courseof aday in various places. Then, a one-dimensional heat conduction model is established to simulate the output surface temperature of steel plate specimens by using the environmental parameters obtained from experiment, and the numerical results are compared with the experimental results to prove its feasibility. On the basis of this model, the influence of different factors on the temperature change of steel structures is studied.
Analysis on bridge health inspection results and maintenance work cost records were conducted targeting road bridges in Kanagawa prefecture, which may provide a helpful perspective for estimation of future maintenance cost of bridges. The inspection results of 336 bridges were analyzed by type of structural members and implied tendency so that corrosion in steel girders and cracking in concrete girders and slabs progress relatively slowly but some types of concrete member deteriorations are found after escalation. The maintenance work cost record showed that total cost accumulation for repairing work of concrete bridges occurs rarely but drastically at one time. Besides, in steel bridges total cost accumulation for repairing increases slowly but steadily due to paint deterioration or corrosion.
The purpose of this study is to detect weld toe cracks generated in out-of-plane gusset welding due to plate bending fatigue test by high-sensitivity magnetic non-destructive inspection (ELECT). It was shown that the difference magnetic vector obtained via subtraction of a magnetic vector of frequency 3 Hz from that of 40 Hz becomes smaller when the fatigue crack propagates. From the ELECT measurement results of the main plate, it can be assumed that the fatigue crack initiates and propagates when the difference vector intensity ratio of sensors 1 and 2 becomes less than 1.
In the previous studies, plate bending fatigue tests were conducted on a steel plate with stud bolt welded upward, and the fatigue limit was less than the fatigue strength class of E in JSSC. This might be caused by the upward welding, however, the fatigue limit of the stud welding itself might become low. In this study, in order to clarify the fatigue limit of stud welded joints, plate bending fatigue tests were carried out. As a result of the fatigue tests, the fatigue limit varied depending on the diameter of the studs, and the fatigue cracks were observed in the plate bending fatigue test under the stress range of fatigue strength class E.
This study investigated the effect of controlled-additional weld using a conventional welding consumable and grinding of weld toe on fatigue strength. The toe radius trended to be larger by the additional weld and grinding of weld toe, and the fatigue strength of this specimen was increased than that of only additional weld. However, when the aiming position of additional weld is too far from fillet weld toe, the dent between fillet weld and additional weld occurs and fatigue crack tended to occur at the boundary between those. The stress concentration factor at the weld toe and the boundary were calculated by FE analysis, it was confirmed that both the fatigue strength and location where cracks occure are explained by the size of the stress concentration factor.
In this paper, the effectiveness of bolting a crack on the stress concentration at stop-drilled-holes repaired by the patch plate is discussed. First, stress concentration at stop-hole by combined patch repair with bolting a crack was measured by the tensile tests. Next, the test results were verified by the finite element analysis. Additionally, large-scale models that ignore the influence of the width of the main plate were analyzed. From test and analysis results, it was clarified that the combination of patch repair and bolting a crack can be reduced the stress concentration at stop-hole more than patch repair. Furthermore, bolting a crack and stop-holes was further reduced the stress concentration at stop-hole compared with the bolting stop-holes.
Fatigue cracks have been reported at out-of-plane welded gussets in main girders of existing steel girder highway bridges on severe traffic routes. In this paper, a simplified method to estimate live load stress of main girders for fatigue design by using load distribution factor (LDF) was discussed. First, structural parameter versus fatigue live load stress relations were investigated based on 22 design data sets computed by grillage analyses of 14 girder bridges designed by the past design code with various structural parameters. Regression analyses based on the data sets were conducted, and simplified equations which provide approximate estimates for the analysis values were extracted.
This paper proposes a method to evaluate fatigue strength under wind loads for clamped distribution line conductors. In our method, the fatigue strength is based on nominal stresses, which are defined by the resultant of the axial stress and the bending stress. The bending stiffness of conductors to calculate the bending stress is estimated by a simple equation derived from a finite element analysis, which is considering effects of the tension and the friction between wires. Our method is verified by fatigue tests assumed the real behavior of cyclic stresses on clamped conductors under wind loads. The results of the tests show the potential of using the nominal stress range to evaluate the number of cycles to failure of a wire and a conductor.
Many fatigue cracks were found in weld joints between vertical stiffener and deck plate in orthotropic steel decks (OSDs). Thus, several retrofitting methods were proposed for the joints in existing structures. In case of new OSDs, separating vertical stiffeners on transverse member from decks is recommended, despite of reducing vertical stiffeness. High fatigue resistance detail without reducing stiffness of the vertical stiffeners is more efficient. This study is aiming to propose a high fatigue strength detail of vertical stiffeners for newly fabricating OSDs. Half-circle-cut detail and fillet detail were evaluated by FEA and fatigue test. As a result, the fillet detail had no fatigue cracks due to high stress reduction, and it could be proposed as an improved detail.
Due to an impact load caused by wheel passing rail joint, fatigue cracks tend to occur around rail joint. In order to evaluate effects of the impact load on fatigue at the deck system of a steel box girder, stress measurement was carried out at the existing bridge. As a result, the impact load at the rail joint generated two types of high frequency natural mode vibration of around 40 and 350 Hz. And, those vibrations increased the range and cycle of the stress at the welding joint of the deck system.
A running test was conducted at the deck girder in order to identify the vibration mode excited by the impact load at the rail joint, and clarify the effect of the rail joint condition on stress at the top and bottom end of the vertical stiffener due to the vibration mode. As a result, it was found that the impact load at the rail joint generated the bending vibration of the main girder and out-of-plane vibration of the web or flange panel, and the rail joint type and the step at the joint affected the stress at the stiffener.
In this paper, the influence of loading direction and loading history on the shear capacity and failure pattern of RC member is studied by two directional loading experiments using full-scale RC columns. Specimens are W1100mm × D1100mm × H3100mm (loading height is 2600mm) RC columns of shear-failure type. The number of specimens is three and each specimen has different loading patterns. As a main conclusion of studies, it is verified that the shear capacity of RC column is increased by 45°diagonal loading and preliminary loading in the orthogonal direction to make pre-cracks.