This paper describes experiments of superstructure/substructure joints for steel bridges, focused on number of studs, embedded length of steel girder, gaps between steel girders and flesh concrete, and bonding effect with reinforcing bar at steel girder embedded corner. Twelve cases of cyclic loading tests were conducted for clarifying these effects, resistance mechanism and resistance rate shared by each item of steel superstructure/substructure joints. Based on these results, along with that evaluating present expression for bearing under lower flange, new evaluation of punching shear force above upper flange is proposed herein.

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 From about 15 years ago, fatigue cracks initiating from weld roots between deck plate and trough rib and propagating into deck plates have been detected in orthotropic steel deck bridges. It is well known that the stress at the weld root and the position of vehicle load are closely related. In order to clarify this relationship it is efficient to use stress influence plane. Using the stress influence plane, stress variation analyses can be easily performed due to vehicle traveling even if the size of the wheel changes. In this study, finite element stress analyses have been done for typical steel plate deck structure in condition of changing the concentrated load position of about 2000 points. On the basis of these results, shape characteristics of influence plane for axial stress, shear stress, maximum principal stress and minimum principal stress are made clear, influence of cope hole and deck plate thickness on the influence plane, and influence of tire size and location on stress variation are discussed.

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 High strength bolted friction type joints are generally used for connecting steel members at construction site of steel bridges. In case of high strength bolted friction type joints, quality management of bolt axial force and joint surface condition is very important in order to assure the slip coefficient (0.45) specified in the design code. In this study, in order to clarify the influence on slip coefficient of high strength bolted friction type joints by painting condition and exposure duration, a series of slip tests was carried out. Parameters in the slip test are thickness of the inorganic zinc-rich paint, difference by paint company and exposure duration. As results, it was found that slip coefficients of test specimens with paint thickness of 50μm or 150μm exceeded 0.45, and they became higher by longer exposure duration after bolting.

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 Concentrating on the Rikuzentakata area, which has suffered tremendous damages from Tsunami triggered by the Great East Japan Earthquake, the video and numerical analyses for simulation of tsunami have been conducted to understand the feature of tsunami including the wave type.
 The tsunami wave running up the Kesen River was a bore wave with crest as around 2m; wherein, it is estimated that flow with the surface gradient in 1/100 primarily impacted on the superstructure of bridge after the wave crest went by. Further, the explanation for bridge outflow was succeeded by evaluating the tsunami impact force from the obtained flow velocity.
 Additionally, via comparison to results of video analysis, it is concluded that good consistency occurred for the surface gradient of general wave shape. Whereas, the steep surface gradient has not been reappeared by numerical analysis for the reason that the ratio of flow velocity to wave velocity is not large enough during the raise of surface elevation.

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 This paper discusses remaining capacity of corroded compressive box-section members which were cut out of a demolished 50-year-old steel truss bridge. Laser surface measurement of corrosion depth and compressive loading tests were conducted for the specimens after introducing artificial local loss section area. As results of the loading tests, it is found that local buckling mode was dominant for specimens with artificial corrosion, while specimens without artificial corrosion showed overall buckling mode at the ultimate state.

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 In paint-coated steel structures, the corrosion tends to initiate not only from individual coating defects but also from a plurality of adjacent coating defects; it should be interference in growth process of the corrosion. However, the influence of size and proximity of the coating defect on corrosion behavior is ambiguous and unclear. In this research, combined cyclic corrosion tests were conducted over a prolonged period using paint-coated steel plates with single and two adjacent circular defects. The test results indicate that the mean and maximum corrosion depths increased with increasing diameter of the single defect of the coated steel plate. The corrosion growth rate for specimens with two adjacent circular defects is greater than that with single defect. Furthermore, in order to clarify the electrochemical mechanism between two adjacent circular defects, time-dependent corrosion current was measured using a model specimen with their defects.

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 More than 50 years have passed since Japan's infrastructure construction era peaked in the 1960's, and a lot of steel bridges have now aged to the point where we need to conduct structural analyses to determine their current residual strength and to develop measures to facilitate future use. Repair, reinforcement and performance recovery are of special concern in environments with high levels of airborne sea-salt, and therefore attention is being directed towards the study of effective countermeasures under such conditions. In this paper we clarify the actual corrosion condition of the original Amarube bridge and present a method to numerically simulate the transport of sea-salt particles that reflects actual geographic and weather conditions in an effort to further knowledge concerning steel bridges in a corrosive environment. We thereby demonstrate the applicability of the simulation model through a comparative study of simulation results and measured values for the original Amarube trestle bridge which was in service for 98 years from 1912 to 2010.

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 The authors have proposed the methods of retrofitting orthotropic steel decks for the fatigue cracks between the deck plate and the U-shaped rib. The method is applying bolt friction joints with L-shaped steel plates by fastening stud bolts for the bottom surface of orthotropic steel decks without traffic control. The stud bolts need high fatigue endurance because they shall be welded and fastened in high tension at orthotropic steel decks eternally. In this study, in order to investigate fatigue endurance of the stud bolts, the cyclic tensile loading tests and FEM analysis were carried out. The obtained results indicate that the steel plate applied the patch plate by fastening the stud bolt have fatigue endurance equal to or greater than steel plate without the patch plate because a force acting at welding zone was transmitted to the patch plate.

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 Approximately 200 repair cases of failed steel bridges owing to fatigue are summarized into an Internet based database. Since the basic system that this database uses is PukiWki, which is a Wiki-type content management system, any users can participate in creating the database, as in Wikipedia. Further, causes of failures, repair methods, service years and occurrence of cracks, and types of welding defects are analyzed using the cases included in this database. In this paper, firstly, the system of the database is introduced. Next, the results of the analyses are presented.

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 In this study, in order to identify crack developing states in the perforation and effect of coarse aggregate on the shear resistance mechanism of perfobond rib shear connectors (PBL), experimental verifications through partial loading tests and standard static tests using 3D scanner and X-ray computed tomography (X-ray CT) have been carried out. The partial loading tests clarified that the coarse aggregate across shear fracture surfaces affect the progress of the cracks, and convex portion of rough crack surface is broken when the load reaches the maximum shear force. The image of X-ray CT demonstrated that the maximum shear force of the PBL increases when a excessive large coarse aggregate lays across the both shear fracture surfaces. Furthermore, the roughness of shear fracture surfaces of PBL were measured with the 3D scanner. The results showed that the standard deviation and the height difference of the irregularities affect the maximum shear force. These experimental facts suggested the failure process and the shear resistance mechanism of PBL with restraints.

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 The temperature dependence of mechanical characteristics of high damping rubber bearings (HDRBs) was investigated through cyclic loading tests under different ambient temperatures, especially sub-zero environment. The ambient temperatures and temperatures inside HDRBs during cyclic loading were different due to self hating, and it is found that mechanical behavior of HDRBs is governed by the inside temperatures. A simple method to estimate the inside temperature was developed. Previous cyclic loading tests results at different ambient temperatures were reexamined based on the inside temperatures to estimate temperature dependence of HDRBs.

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 In this research, nonlinear dynamic analysis method using equivalent single degree of freedom model is proposed for seismic design of railway embankment. The response of embankment calculated by proposed method is well consistent with the response by 2D finite element method. From the results of static push-over analyses for various embankments, the model parameters used for the proposed method are characterized. These parameters can be represented by simple information such as the height of the embankment. Since proposed method can evaluate the dynamic response of railway embankments more convenient than conventional method, it is useful as the response evaluation method for a huge number of railway structures.

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 The differentiability of the phase spectrum of earthquake ground motion is discussed and a new numerical scheme is proposed for the calculation of the group delay time of earthquake ground motion.
 In addition to the discontinuity due to the “unwrapping” procedure, the phase spectrum can theoretically be non-differentiable when the Fourier transform of the earthquake ground motion is located at the origin of the complex plane. This implies that the group delay time cannot be defined for frequencies for which the Fourier amplitude spectrum is zero. From such a point of view, the conventional theoretical link between the group delay time and the temporal characteristics of earthquake ground motion is reviewed. It is confirmed that the non-differentiability does not affect the link.
 Even when the Fourier transform is not located precisely at the origin of the complex plane, the numerical calculation of the phase increment and the group delay time can be unstable when the Fourier transform is located close enough to the origin. To mitigate the difficulty, a new numerical scheme is proposed for the calculation of the group delay time of earthquake ground motion. The new method uses the ‘modified’ group delay time, which is defined as the multiplication of the conventional group delay time with the squared Fourier amplitude spectrum. The ‘modified’ group delay time can be defined even for frequencies for which the Fourier amplitude spectrum is zero. In addition, the ‘modified’ group delay time is numerically stable.

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 It is necessary for efficient maintenance to predict behavior of deterioration factors by simulation instead of observation. In this paper, the change of salt environment due to anti-freezing salt scattered by vehicle running was predicted. When a rectangular-modeled vehicle runs at 50 km/h or 80 km/h in windlessness, anti-freezing salt was scattered toward the side direction in the range of 1.5 times as long as the vehicle width, and toward the vertical direction in the range of the same as the vehicle height. When a vehicle runs at 50 km/h in the cross wind whose speed is 10 m/s at 10 m height, anti-freezing salt was carried to more than 5.5 times as long as the vehicle width on the leeward of the cross wind, and scattered toward the vertical direction in the range of more than 2 times as long as the vehicle height. From this paper, the necessity is confirmed to pay attention to structural design and maintenance considering the salinity supply due to anti-freezing salt scattered by vehicle running.

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 This paper investigates fatigue strength of the longitudinal-to-transverse rib connections between U, V, or plate ribs and slit or non-slit transverse rib webs in orthotropic steel decks. Fatigue strength of the each connection was evaluated under the severest load positions which take traffic load moving into account. As results, the severest load positions were clarified to be not upon but some away from the target connections. Changing the slit connection to the non-slit connection reduced the local stress ranges on the connections with the U and the plate ribs by 75 and 58%. In addition, the local stress range of the non-slit connection with the V rib was lower than that with the U rib by 39%.

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 Recent Development of High Performance Computing has enabled utilization of Computational Fluid Dynamics (CFD) in designs in the engineering field. However, the accuracy of simulated wind forces on a bridge girder using CFD as well as the accuracies of onset velocity and amplitude in fluid-structure interaction problems such as flutter have not yet been investigated well. Furthermore, the calculation time still needs to be improved in order to utilize this CFD in the wind resistant design in a real project. Therefore, in the present study, the accuracy of mean wind force coefficients and flutter derivatives of a box girder using Large Eddy Simulation (LES) is investigated by comparing the results with experimental data from past research. The effects of span-wise domain size on mean and fluctuating wind force and flutter derivatives are also investigated for the purpose of reducing the calculation time by reducing the span-wise domain size in wind resistant design of long-span bridges. Mean wind force coefficients and flutter derivatives could be evaluated by LES with comparable accuracy to a wind tunnel test. It was shown clearly that the effects of span-wise domain size on mean wind force coefficients and flutter derivatives are small while there are relatively large effects on fluctuating wind force coefficients. Therefore, span-wise domain sizes can be reduced for evaluation of mean wind forces and flutter derivatives.

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 Corrosion of a steel I girder bridge is often found at the girder end and researches to evaluate the load carrying capacity of the corroded girder end have been carried out. However, load carrying capacity of a bridge system corroded at the girder end is not clear, and seismic performance of the girder end is also unclear. In this study, load carrying capacity of a bridge system corroded at the girder end is examined by full scale FEM model. In the case with corrosion at the partial girder end, bridge system behavior, as the intact girder end shares load acting on the damaged girder end, is observed, and the resistance of the damaged girder is higher when considered as part of a bridge system.

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 Corrugated steel plates are used to web plates of a composite prestressed concrete bridge. This paper presents measured residual stress distributions of corrugated steel plates and the results are compared with the case of flat steel plate. Each 6 specimens are fabricated for web plates without flange and with flanges. The corrugated shape was made trapezoidal and the combination of wave height and panel width in the cross-section were changed. From the measured results, the residual stress distributions of the corrugated web section without welding flange is not a uniform distribution due to the influence of press braking, but the residual stress varies within 10% of the yield stress. On the other hand, the residual stress distribution of the web section with welded flanges is rapidly changing in the range of about 20% of web height from the edges, there is a uniform tensile stress of about 2% of the yield stress in the internal web. As the corrugated steel plate had an accordion effect, the residual stress distribution in member axis direction differences in comparison with the case of the flat steel plate.

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 This paper evaluated the ultimate shear strength of pre-stressed high-strength concrete pile (PHC-Pile) under tensile or low compression axial force subjected to antisymmetrical moment experimentally and numerically. First, shear monotonic and cyclic loading tests of real size PHC-Piles were carried out under different axial forces by the loading tests. Then, the test results was simulated by 3D-RBSM, which is a discrete numerical model and can describe crack development accurately, to confirm the applicability of the method. Moreover, the influence of the ultimate shear strength on axial force, shear span ratio, pile diameter, spiral stirrups and cyclic number was investigated by using 3D-RBSM. Based on the experimental and numerical investigation, it was confirmed that the PHC-Pile used in this paper has enough performance on axial force until the ultimate shear strength. In addition, it was shown that the change of the ultimate shear strength on axial force was larger than the design equation, and safety margin of design equation may become very small in the range of tensile or low compression axial force.

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 Fatigue tests have been carried out on out-of-plane gusset welded joint specimens under axially pulsating compressive stresses, reversed stresses and pulsating tensile stresses in order to clarify the fatigue crack initiation and propagation behavior, and fatigue strength under compressive cyclic stresses. In the fatigue tests, the multiple repeated two-step stress tests have been also performed for the purpose of leaving beach marks in a fatigue failure surface in addition to the constant amplitude stress tests. The fatigue test results suggest that the fatigue crack stops propagating under the pulsating compressive stresses after the crack penetrates the main plates and extends to a certain extent, the fatigue strength and propagation behavior before it penetrates the plate under the pulsating compressive stresses are the same as those under the pulsating tensile stresses.

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 Fixed point load fatigue tests (four points bending tests) and the moving load fatigue tests (wheel load driving tests) on I-section girder specimens with web-gusset welded joints have been performed in order to make clear fatigue crack initiation and propagation behavior from the weld toe of the joint and the fatigue strength under variation in principal stress direction. The test results suggested that the fatigue strength under moving loads is lower around 20 to 30% than the strength under the fixed point loads, and fatigue crack extending along the weld toe is long compared with that in fixed point loads, and the fatigue crack after leaving from the weld toe propagates in more inclined direction compared with the direction perpendicular to the principal stress direction.

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 It is known that high strength bolted joints treated with zinc-rich paint have a characteristic of large bolt axial force loss by relaxation. In this study, the friction type of high strength bolted connection specimens were made on steel plates, in which contact surfaces are to be rough without mill scale and have inorganic zinc-rich paint, then slip tests and relaxation tests were carried out on these specimens. From these results, we discussed the applicability of high strength bolted joints treated with zinc-rich paint under 15%- additional bolt axial force.

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 Snow weight information is of interest to wide area of engineering and science. However, its direct measurement is costly in contrast to snow depth measurement where variety of methods from visual measure to advanced laser or remote sensing are available. Hence, snow weight information is usually sparse both in time and space compared to snow depth information. This paper proposes a hysteretic trilinear model to estimate snow weight from snow depth history. The model is verified by continuous monitoring data of snow depth and weight operated by National Research Institute for Earth Science and Disaster Resilience. The model is shown to match observed data well and selection procedure of parameters for the model is established. In addition, application to visual measure with sparse measurement in time is studied.

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