We conducted hybrid on-line tests to study the behavior of soft clay ground during an earthquake. The objective site has a quay on the soft clay ground. We showed that we could estimate the maximum acceleration from the shear strength and the shear stiffness of the clay during an earthquake. If the shear stress of the clay reaches the shear strength during an earthquake motion, the maximum acceleration decreases but the strain does not change. We showed that the void ratio decreased and consolidation yield stress increased because of the ground settlement after earthquake.

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This study examines the effect of axial force fluctuation in supporting columns of a traditional wooden temple on the seismic response of the structure. The main structure and high wooden stage of the Kiyomizu Temple, a Japanese national treasure located in Kyoto, were reconstructed in 1633 following a fire. The temple was modeled numerically for three-dimensional inelastic earthquake response analysis. An inelastic vertical spring was set at the base of each column to represent uplift during an earthquake, coupled with a horizontal spring set to represent variable friction corresponding to the varying axial force of the column. The results reveal that axial force fluctuation has little effect on the maximum seismic response of the structure. However, this effect does influence the residual displacement of each column, particularly near the perimeter of the structure.

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This paper has tried to reveal the cause of irregular surge of water distribution volume and irregular decrease of water pressure respectively just after an earthquake. First the cause of a surge in water distribution volume is examined in a statistical manner based on the observation data by Osaka Waterworks Bureau (OWWB). Next the movement of water inflow into the water receiving tanks just after earthquakes are numerically examined using acceleration waveform collected by OWWB's earthquake monitoring system. The relationship between the sloshing phenomenon caused to water receiving tanks and a sudden surge of water distribution volumes was considered. Furthermore, the sloshing phenomenon of water in receiving tank was examined using hypothetical acceleration waveform of Tokai-Tonankai earthquake.

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We study variations of predicted ground motions on the basis of a recipe for strong-motion prediction and propose a technique for evaluation of variation in the predicted ground motions. In this article, we consider only aleatory variabilities in source parameters among all possible variabilities, such as, those in the source parameters, the propagation characteristics and the site characteristics. We use a Monte Carlo simulation to estimate variations and adopt the Latin Hypercube Sampling (LHS) method to reduce computations. We estimate the variation of predicted ground motions in PGA, PGV and response spectrum at a specific site and calculate average and standard deviation of normal distribution, and also we evaluate the special variation in the area by using the space distribution maps of standard deviation. It is shown that the variations in the predicted ground motions on the basis of a recipe are comparable with those of attenuation formula.

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Immediate casting technology of earthquake motion has been becoming possible by development of information technology. This paper describes the effectiveness of active disaster prevention system using immediate casting information of earthquake motion. This system consists of high density seismological observation network in certain focused area. This system makes possible to expect the earthquake motion by using time lags between transmission speed of information and propagating speed of earthquake. This observation network system was actually constructed in the utility tunnel of University of Tsukuba and earthquake motion observation was carried out. The anti-resonance control for the variable stiffness structure is simulated using the observed acceleration data. The effectiveness of this disaster prevention system is recognized.

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Ground motion inputs to building structures are multidimensional and cause complex responses. In this paper, particle orbit characteristics of horizontal ground motion are described. A 2-layer subsurface structure model is used for analysis based on the 1-dimensional wave propagation theory. Shear torsional motions and motion coupling between translational and torsional motion are considered. The site response and the horizontal particle orbit of ground motion are characterized by the coupling parameters. The effects of the coupling parameters to the ground motion are investigated through a theoretical approach and numerical experiments.

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