In this study, by utilizing the power generation characteristics of vibrated electret, a new passive type vibration velocity sensor was developed. In order to analyze the information on the vibration from measured time histories of voltage, a new electret electrode structure was proposed based on the numerical simulation. In constant amplitude vibration tests, the relationship between velocity, measured voltage and vibration frequency was clarified. As a result, the generated voltage and velocity have a linear relation-ship with a fixed angle that depends on the frequency, and the relationship between generated velocity per unit velocity and frequency was obtained as transfer function to convert voltage to velocity. For random vibrations, data processing method using the transfer function was proposed. Furthermore, due to the characteristics of the developed sensor, displacement and acceleration can be also obtained. Finally, the measurement on an actual bridge was conducted to examine the applicability of proposed sensors.

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 In standard design codes for civil infrastructures, earthquake motion characteristics are often defined by acceleration response spectra for the convenience of design purpose. The earthquake motion time history necessary for dynamic analyses are requested to be compatible with those design response spectra. In the current design code only elastic acceleration response spectra are considered for this purpose. But in the design codes taking into account the level 2 earthquake intensity structures are designed by considering their dynamic behavior in non-elastic region, therefore if their seismic performance is checked by dynamic analysis using an earthquake motion compatible with the elastic acceleration response spectrum, it has been pointed out for long time that its non-elastic behavior cannot be properly guaranteed. Moreover non-linear response spectra with the ductility factor as a design parameter are often used for designing structures to simplify the design method in the performance-based design. Therefore in this research we develop a method to define an earthquake motion simultaneously compatible with a group of non-linear response spectra. This method can modify the selected original time history of earthquake motion as to be compatible with non-linear response spectra. For this purpose using the method that time and amplitude adjusted short period Ricker wavelets are superposed to the original time history and the equivalent linearization technique, we develop the algorithm to adjust the amplitude of each wavelet so that a recalculated nonlinear response spectra using the modified earthquake time history can converge to the group of the target nonlinear response spectra.

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 The spatial correlations of fluctuating lift forces were evaluated using pressure measurements in the smooth flow and grid turbulences. The effects of flow characteristics and side ratios on spatial correlations are investigated. The spatial correlations of fluctuating lift forces on cross sections with completely separated flow are determined by the vortex scale as well as the vortex intensity. The function which expresses the spatial correlations is proposed, which enables the estimation of spatial distribution of correlation coefficients. The correlation length of fluctuating lift forces can be estimated by drag coefficient at a certain accuracy.

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 Dynamic behavior of a large scale steel cellular bulkhead was investigated by centrifugal model test and simulation analysis by both two-dimensional model and 3-dimensional model. The bulkhead moved toward front side with settlement and inclination and the bulkhead showed the behavior as the rigid body. However the cell and the arc showed complicated behavior as to both vertical direction and circumferential direction. The simulation results were fairly good agreement with the test results as to its movement. However the shearing deformation of filled sand in the cellular was overestimated by 2-dimensional model whereas the large Mises' stress was calculated by 3-dimensional analysis. The calculation results by current design method gave safety side results but the complicated stress behavior on the cellular was not estimated by current design method.

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 It was confirmed that UIT (Ultrasonic Impact Treatment) gives excellent fatigue strength enhancement of welded joints through a lot of experimental researches. Main factor of increasing the fatigue strength by UIT is the introduction of compressive residual stress rather than the improvement of weld toe shape. Further improvement of fatigue strength is expected by introducing high compressive residual stress which can be realized by increasing the static strength of steel.
 The purpose of the present study is to clarify the influence of static strength of steel on the fatigue strength of web-gusset welded joints with UIT. For this purpose, fatigue tests on the joint specimens made of SBHS400, SBHS500 and SBHS700 steel have been performed, and fatigue crack initiation and propagation behavior and crack opening-closing behavior due to the compressive residual stresses have been examined.

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 This paper showed the failure mechanism of steel-concrete composite bridge deck having studs and ribs subjected to repetition of moving load by using 3 dimension nonlinear FE analysis. First, the property of interface element between steel and concrete was identified by sensitivity analyses. Next, progress of strains of concrete and steel elements obtained in simulation were examined throughout all the loading program of wheel running test. In particular, special attention was devoted to the processing of horizontal cracks inside concrete. Furthermore, static analysis was performed to highlight the difference of failure process given by the fixed point load and that caused by the moving load. Considering a particular failure mechanism of the deck under moving load, to set a proper limit states and control level for engineering practice was strongly required.

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 Two hysteretic models for reproducing restoring forces of laminated rubber bearings are proposed. One is including only hardening effects in large deformation range and the other is modeling experienced shear strain dependency in addition to the hardening effect. Tangent modulus of those models are also derived. The key point of those models is that they are extended directly from bilinear hysteretic model, and the restoring forces of them could be computed easily by using the bilinear model. Then, their accuracy in predicting seismic responses is evaluated. From the seismic response analysis, it is found that modeling of the hardening and the experienced shear strain dependency are important factors in order to accurately predict responses of the piers and bearings in base-isolation bridges.

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 In order to develop surface state monitoring methods for weathering steel bridges with supplemental rust controlling surface treatment, investigations of a model bridge made of weathering steels exposed to severe marine environment for 14 years were carried out. Various values obtained by non-destructive methods such as visual inspection, ion transfer resistance measurement, rust thickness measurement, residual metal thickness measurement were compared with those obtained by destructive methods such as cross sectional optical microscope observation, and electron probe micro analyses in terms of rust states. In doing so, useful fundamental data in terms of degradation analyses for weathering steel structures have been accumulated. Also, validity of the nondestructive methods including the ion transfer resistance measurement was confirmed.

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 The conventional seismic standard specifies that the seismic inertia force of trains is modeled as a uniformly-distributed load which has upper limit force of 30% of railway vehicle weight, However; this method has not been validated sufficiently. The object of this paper is to develop a reasonable seismic design method of railway structures which takes dynamic effect of railway vehicles into account. As the result of numerical simulations, it was found out that the structure response under earthquake motions varies in the range of -50~20% at its maximum due to the dynamic effect, depending on the characteristics of earthquakes, the degree of the plastic behavior of structures and the yield frequency, and that the structure response significantly increases due to concentrated load effect of the train if four wheel-axises sandwiching the coupler is placed on a structure at the time of the maximum acceleration of earthquake motion, although it is a rare case. In addition, as a simple method of modeling train weight in seismic design, an equivalent weight method which evaluates the dynamic effect of the railway vehicle using the equivalent weight ratio β_eq was proposed. For heavy structures such as concrete structures, the equivalent weight ratio in the proposed method and that in the conventional method are the same. For light structures such as steel structures or composite structures, it changes depending on parameters such as the weight ratio of the structure / vehicles.

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 In this research, we developed the monitoring system to detect the bridge condition and transmit the data to the train passing on the target bridge. The characteristic of the system is to be able to operate only with the power generated from the bridge vibration. In order to achieve this power harvesting technique, the bridge member, the configurations of a piezoelectric device and circuit architecture, which are suitable for the power harvesting, were examined. From these results, we made the prototype monitoring system and verified the operations at the existing bridge. In this verification, the prototype system demonstrated to measure and to transmit the data five times with the power generated from the bridge vibration induced by a running train composed of ten cars, and the train received those transmitted data.

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 We decomposed the earthquake motion phase (EMP) into two parts such as a linear delay part and a fluctuation part. Based on the assumption of the identically independent distribution characteristic of phase difference on the fluctuation part of EMP we derived that the EMP should be defined at least as a Brownian motion process. More generally we found that the EMP could be defined as a fractional Brownian motion (fBM) process. A simulated sample earthquake motion phase using the fBM process can represent well several observed earthquake motion characteristics and can simulate a very realistic earthquake time history. The effect of uncertainty of EMP on the earthquake motion amplitude was studied by taking expectation calculus on the uncertainty part of EMP using the probability density distribution function which was derived by considering the fractal characteristics of observed EMP. Based on these analyses the physical meaning to model the EMP by using the fBM process was clearly defined.

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 The seismic deformation method to evaluate the axial 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 axial deformation of cylindrical underground structure appropriately unless frequency of the seismic wave is high and the axial wavelength is short. Moreover, the solution calculated by the seismic deformation method shows good agreement with that calculated by the eigenfunction expansion method. The elastic foundation spring used in the seismic deformation method should be derived with considering the influence on the wavelength in perpendicular to axial direction. Axial deformation of the structure is overestimated when the free-field ground displacement instead of the excavated ground displacement is inputted for the seismic loading.

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 A new technology has been developed for high strength bridge wire strands: steel wires are galvanized with zinc (Zn) and aluminium (Al). The strands galvanized with Zn-Al are expected to have higher corrosion resistance than the Zn galvanized ones. The steel wire with a diameter of 5mm coated with Al (10%) and Zn (90%) alloy is produced and corrosion acceleration tests have been conducted and the corrosion resistance is compared with the steel wires coated with Zn. The steel wires are kept under three different corrosion environments: kept at a relative humidity (RH) of 60%, kept at a RH of 100%, and wrapped with wet gauze which simulates the wet condition. The wire specimens are kept in the thermo-hygrostat at 40oC for 150 days.
 The mass loss due to corrosion under the relative humidity of 60% and 100% is much smaller than that under the wet environment, and there isn't much difference between Al-Zn coated wires and Zn coated wires. On the other hand, the mass loss of the steel wires coated with Al-Zn is distinctively smaller than those coated with Zn under the wet condition. The mass loss of the NaCl attached wires is twice larger than that without NaCl under the wet condition.
 The corroded wires are investigated by EPMA analysis showing that the corrosion product of Zn is loose and easy to exfoliate from the steel layer. On the contrary, the corrosion product of Al-Zn alloy is dense and hard to exfoliate from the steel layer. This difference is the reason of the superiority of the Al-Zn coated wires.

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 This paper deals with a human-induced lateral vibration on a existing pedestrian suspension bridge with the center span of 62.4 m which is constructed in an amusement park located in Osaka prefecture. Based on full scale measurements under the walking load of 20-30 pedestrians, either 1st symmetric or 1st asymmetric lateral vibration is observed. It seemed that the pedestrians were very difficult to walk through the bridge from end to end when these lateral vibrations were occurred. 18 acrylic containers each with size of 450mm×300mm (water depth of 60mm) were used as TLDs for the 1st symmetric vibration. 36 acrylic same containers with size of 300mm×450mm (water depth of 60mm) installed in the opposite direction were also used for the 1st asymmetric vibration. It was confirmed that suppression with TLDs might be useful in decreasing the vibration level.

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