It is common knowledge that damping properties are important in evaluating safety of structures or running safety of railway vehicles during earthquake. For instance, it is pointed out that the differences of damping constant of railway structures may have caused the different damages of structures in recent earthquakes. That's the reason why it is very important to evaluate damping properties for extracting such railway structures as to attract special attention in seismic assessment. However, there is no adequate evaluation method of damping properties at present because there are only a few measurement examples for damping properties and the occurrence factors of damping are very complex. In this study, we measured damping constants of railway viaducts of various structural types and in various ground conditions by using two vibration measurement methods named impact vibration examination and microtremor measurement. As a result, we can notice that the ratio of the structural period to the ground's ones is correlated to the damping constant, and we propose the evaluation method of damping constants of railway viaducts. Furthermore, we propose the extraction method of low damping viaducts regarding running safety by applying the proposed evaluation method.

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 Strain measurement point (reference point) for estimating fatigue durability of orthotropic steel deck in consideration of fatigue crack propagating into deck plate from weld root between deck plate and trough rib, where the transverse rib is connected, is discussed through FE analyses on orthotropic steel deck model. Here, relationship between strain at reference point and stress at the weld root are compared on the basis of the strain influence plane and the stress influence plane obtained from FE analytical results using a lot of points of concentrated load. The results suggest the location “the deck plate undersurface 5mm away from weld toe on the the deck plate” is the most suitable as the reference point.

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 Several studies on the ultimate limit state of the high strength frictional bolted joints considering the behavior after major slip has been conducted. We proposed the deformed bearing limit state as the ultimate limit state of the high strength frictional bolted joints, which is defined by local plastic bolt hole deformation. We also revealed the influence of end distance and bolt pitch on the relationship between bolt hole deformation and the deformed bearing limit stress by tensile tests. In this study, the same tests whose considered parameters are width, thickness, the number of bolts and bolt tensions were conducted to clarify the influence of those on the above relationship focused on the net cross-section yielding and shear yielding of connected plate, and the yielding of high strength bolt. Obtained from the results, it's confirmed that 10% deformed bearing limit stress, when the bolt hole deformation reaches 10% of bolt diameter, is the concave function consisted by the ratio shear failure resistance by net cross-section failure resistance and its ratio to maximizing the bearing stress reach about 1.

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 The seismic deformation method to evaluate the longitudinal bending deformation of cylindrical underground structure is reconsidered through the exact solution based on the eigenfunction expansion method. The results show that the seismic deformation method can evaluate the longitudinal bending deformation of cylindrical underground structure when the structure is treated as an elastic shell, with the surrounding ground treated as elastic foundation springs in axial and axis orthogonal directions and the input ground displacement treated appropriately. On the other hand, conventional seismic deformation method that assumes the structure as a beam overestimates the maximum axial strain of the lining because beam theory ignore the equilibrium of force in the axial direction.

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 It is necessary to immediately decide whether repair, in particular, emergency repair is necessary due to corrosion reduction of gusset plate on the lower chord in steel truss bridges. Incidentally, since the thickness of the gusset plate is determined from the stress state in the neighborhood of the connecting portion between the diagonal member and the gusset, even thought the requirement for thickness of the gusset plate is not satisfied, the possibility of necessary to immediate repairing is seem to be low. On the other hand, since the stress states are complicated, finite element analysis is used for checking this part and this work is takes much time. Therefore, in this paper, a method to quickly and easily evaluate the stress state of this part is proposed by the equilibrium condition and some assumptions. In addition, it shows the residual thickness when von Mises stress of this part due to the corrosion reduction is equal to the allowable stress, and suggests maintenance policy based on this plate thickness.

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 For the mitigation of noise accompanied by passages of the ultra-high-speed trains running at 500 km/h, a hood of a concrete segment frame structure was developed and installed on the Yamanashi test line. Through the on-site measurements, it was found that the effect of structure-borne noise generated by vibrations of the hood in the event of the train passages was not negligible and therefore its reduction was considered to be essential. In this paper the effect was carefully investigated by analyzing the measured data and by simulating with mathematical models, and a hood structure with a greater noise mitigation performance was proposed. A hood with the new structure was produced accordingly whose effectiveness was then demonstrated through laboratory tests and on-site measurements under the passages of the ultrahigh-speed trains. Also a method to estimate the noise level taking into account the structure-borne noise is also worked out and proposed. The estimation with the proposed method showed a fair agreement with the field measurement data, and therefore, the method is expected to serve as a useful tool to provide reasonable noise level estimation for a hood section in the future.

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 In this research, we investigated the relationship between the tsunami acting force to the girder and the wave period of tsunami.
 Firstly, hydraulic experiment was conducted with the tsunami, which has a long wave period such as 15 min. As a result, the wave can be classified into steady flow type, and the horizontal acting force can be evaluated as a function of drag coefficient and velocity. Secondly, comparison with other experimental results was conducted, the relationship between the tsunami acting force and wave period of tsunami was obtained. Bore wave type tsunami are dominant in a wave tsunami., and steady flow type tsunami are dominant in a long period tsunami.

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 In order to ensure the ballast stability on the bridge, the upper limit of deck acceleration has been established in European technical standard. However, both of the measurement and simulation in the European past studies have covered only entire bridge dynamics. This study conducted the field measurement up to 374 km/h train running and the numerical analysis by vehicle-bridge interaction model focusing on the deck member local vibration of composite box girder in Italian high-speed railway. As the results, responses related to the high-order deck local vibration modes at 20-30Hz are dominant components in the high speed range exceeding 300 km/h by 7^th and 8^th resonances with vehicle length. These local resonances cause the 1.3 times greater of maximum amplitude at the deck member than the girder. In addition, the results of numerical study could clarify the impacts of each member specification on the deck acceleration, and lead the method to set the maximum modal number required for the high precision numerical calculation.

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 The authors have proposed a corrosion damage evaluation method for corroded steel members to estimate rust layer and residual thickness. In this method, detected voltage signal obtained by a low frequency eddy current of 500 Hz or less was used as an index. In this research, in order to further advance the method and to simplify the measurement system, a more sophisticated method utilizing a phase characteristic which is considered to be able to simultaneously estimation of thickness information together with the detected voltage has been investigated. Firstly, to clarify the low frequency eddy current characteristics assuming the difference in damaged condition by numerical simulation was performed. Then evaluation method focusing on the phase between the detected voltage and the input current and the detected voltage as an index to capture the differences has investigated. Based on results of all process, a corrosion damage evaluation method focused on phase characteristics which can obtain information of rust layer and residual thickness simultaneously was proposed. Finally, the applicability of proposed method was clarified by experiment.

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 On the Hanshin Expressway, an actual live load survey was conducted in 1982. After that, the live load situation has changed due to expansion of network and revision of vehicle restriction ordinance. Therefore, we investigated the actual live load using the data of the axle load meter and ETC vehicle data in 2010.
 As a result, we clarified the characteristics of the weight and axial weight of the Hanshin expressway. Moreover, compared with the survey results carried out in the past, we clarified the change over time. In addition, comparison with design live load and evaluation of fatigue environment for steel deck were conducted.

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 This paper investigated seismic design methods in consideration of earthquake-induced repetitive pounding in adjacent railway RC viaducts. Detailed pounding simulation revealed that when the over-hanging slab pounding occurs, the coefficient of restitution decreases by about 0.2 due to the conversion to the wave energy propagation into superstructures, and decreases by about 0.6 at the maximum due to the conversion to the energy consumption derived from the material nonlinear hysteresis. A simple contact model has been developed for evaluating the wave energy propagation component and the hysteresis energy component by a dashpot and a nonlinear spring, respectively. Overall analyses using this contact model showed that the response displacement of the structure may increase up to 70% at the maximum. Based on the findings, three methods were proposed for estimating response increases and the gap between structures: a simplified formula, pounding energy method, and simple contact model.

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 The shear resistance of a perfobond strip is affected by the dimensions of the concrete block, rib plate thickness as well as perforation diameter and concrete compressive strength, when a penetrating rebar is not arranged inside the perforation. Authors previously proposed the design formula to evaluate the shear resistance of a perfobond strip based on the above factors using the specimen with the rib plate embedded in the concrete block. However, when the rib plate with perforations is welded to the base steel plate and the concrete block is arranged on one side of its base steel plate, it is considered that the restrained condition around the perforation in this case is weaker than the one in the perfobond strip used in the previous study.
 In this study, a series of push-out tests were conducted by using the specimen in which the rib plates with perforations were arranged on both sides of the base steel plate and a concrete block was arranged separately on each side of the base plate. As a result, the previous formula proposed for evaluating the shear resistance of the perfobond strip was revised to consider the difference of rib plate and concrete block arrangement.

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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 have inorganic zinc-rich paint, then slip tests were carried out on these specimens under 15%-additional bolt axial force.

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 By calculating the stress variations at the weld root due to passing of 8 types of vehicles (car, light truck, medium truck, large truck, dump truck, tanker, semi-trailer, bus) on steel plate deck using a stress influence plane which was given in the previous studies, the influence of lane mark position on fatigue damage index has been examined. In this calculation, plural positions of weld root in addition to a certain position have been paid attention. The results obtained here suggest that moving a lane mark position around 300mm decrease the index by around 50% in the case of a certain position, and by around 25% in the case of plural positions.

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[in Japanese]

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