A bridge vibration energy harvester has been developed in this paper using a Tuned Mass Damper (TMD) system, named hereafter Tuned Mass Generator (TMG). To harvest and make use of the unused reserve of energy the aforementioned damper system absorbs, an electromagnetic transducer has been applied. To investigate the configuration of the tuned mass generator considering performances of energy harvesting, the tuned mass generator is applied to an actual expressway bridge. According to the experiments on the trial bridge, it has been demonstrated that TMG generates electric power in watts order, which is much higher than other energy harvesters of structural vibration generators. It has been also clarified that TMG harvests enough energy for sensors or other low-power devices.

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 It has been confirmed that batter piles have response reducing effects caused by their out-of-phase rocking motion and input loss, in addition to a static rigidity increasing effect. Viaducts have recently been designed in consideration of the energy absorption caused by damage to the column or pier in an earthquake. However, the response reduction effects when the superstructure is damaged have not been examined in detail.
 In this study, we carried out vibration model experiments of the rigid frame viaduct with plastic hinges of column on the batter piles as well as numerical simulations. As a result, the response reduction effects were confirmed when the column entered the plastic region. In addition, it was shown that the effects are suitably evaluated by an appropriate model, in which the rotation component of the effective motion is considered.

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 A new type of tidal energy converter utilizing the flow-induced vibration of a columnar pendulum is investigated. Strong drag force and moment act on the pendulum base of this tidal energy converter, and hence it is important to clarify the characteristics of these hydrodynamic forces for the design of the pendulum. Then the drag force and moment acting on the circular cylinder pendulum were measured in the circulating water channel test. This test revealed that an oscillating pendulum induces stronger hydrodynamic forces than a stationary one. The drag and moment coefficient have a higher correlation with tip speed ratio than angular amplitude of the pendulum oscillation.

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 Adoption of sliding bearing to a bridge structure is to be effective for seismic force mitigation against a large earthquake, but restoring force transfer is required to damage prevention against a small or medium earthquake. Then the authors consider combination use of sliding bearing and knockoff device, which works as the restoring transfer device only against the small or medium earthquake for damage controlling method of bridge structures. This paper investigates applicability of the bearing system to a viaduct through seismic response analysis and the merits of the method are evaluated in comparison with the cases using conventional types of bridge bearing.

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 In Japan, a lot of steel-plate concrete composite decks have been constructed instead of RC slabs. The composite decks were also required appropriate maintenance to keep high durability. The rational nondestructive inspection has been required to detect unfairable fatigue damage at welding parts. In the Robinson type composite deck, occurrence of fatigue deterioration of studs welded on bottom steel plate was one of the phenomenon which should be avoided. Therefore the authors have studied how to detect fatigue deterioration in the concrete. In this study, the authors tried to apply a performed infrared stress measurement by infrared thermography. Then from the data of the thermography method measured during wheel running fatigue test for a composite deck, the authors could find out a useful method to detect and to evaluate fatigue damage of the studs.

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 The stress variation at the out-of-plane gusset welded joint on a steel I-section girder web has been examined when a load runs over the girder. This examination is essential in order to establish the fatigue strength evaluation method in the stress field where the direction of principal stress changes. For this purpose, stress measurement tests for the steel I-section girder specimen with out-of-plane gusset welded joints under the moving load, and finite element stress analyses for the specimen have been performed. The results indicate that the angle of shear stress and principal stress change with gentle slope due to the influence of vertical direction stress, the positions along weld toe in which the largest major principal stress occurs gradually changes by the load position, the stress at the welded joint located at the upper potion on the web is prone to be high compared with that at the lower position because of a difference of vertical stress magnitude.

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 In the case that the railway bridge piers were devastated by flooding, the train operation should be restarted as soon as possible in order to reduce losses due to service disruption. Therefore, the emergency retrofit methods on the devastated piers should be established. In this paper, the case study of the emergency retrofit methods that was performed in past by railway companies was performed in order to investigate the relationship between the damage types and retrofit methods of the devastated piers. Additionally, the process flow of the retrofit methods was proposed on the basis of results from the case study.

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