Although the seismic response reduction effect with load sliding (slide effect) is not considered in general structural design, consideration of this effect may contribute to a more rational structural design. In the present study, in order to obtain the basic characteristics of the slide effect for an elastoplastic frame, shaking table tests were carried out on a single-story elastoplastic steel frame while varying certain parameters. In addition, the vibration energy due to deformation of the frame, the sliding energy generated by the sliding of the weight, and the input energy were calculated from the experimental results, respectively. Based on the experimental results, the vibration energy of the frame and the input energy were found to decrease due to the occurrence of friction energy by the sliding of the weight. The seismic response analyses were carried out for the analytical models considering the slide effect in order to calculate and discuss the energy balance of the hysteresis energy of the frame, the friction energy of the weight, and the damping energy. Based on the analytical results while varying the same parameters as the experiment, the friction energy of the weight was found to be strongly influenced by the characteristics of the input seismic motions. However, the ratio of the friction energy to the input energy is roughly constant for the seismic motions of which maximum velocity is 0.3 ~ 0.5m/s.

Aleatory variability of observed ground motion amplitudes was investigated by analyzing the variation of response spectra of ground motion record pair at the same station from two events with the same magnitude, source location, and focal mechanism. The standard deviation of aleatory variability evaluated from all the record pairs was about 0.3 - 0.45, even the variation includes the earthquake type or the period range. The standard deviation around the period of 0.2 s was slightly large, and the dominant period of standard deviation shifted depending on earthquake magnitude. In addition, the standard deviation from the distant record pairs was relatively small. The difference in the rupture pattern of an event pair is considered to be one of the factors of the aleatory variability subjected in this study. The standard deviation derived from the records of crustal earthquakes was larger than that of subduction earthquakes, indicating difference in distance distribution of the records. There are no clear differences in the magnitude dependency and the distance dependency of the standard deviation for earthquake type.

Road blockage caused by collapsed buildings hinders evacuation, firefighting, and lifesaving activities. It also expands the damage of fire spreading. We propose a method to evaluate the disaster reduction performance of a district with three indices of fire extinguishing probability, ratio of non-burned buildings, and evacuation achievement rate. In the evaluation of these indices, we use the Monte Carlo method based on building collapse rate, fire outbreak probability, etc. As a result of evaluating the proposed indices for two virtual districts: one with latticed road and the other with the radial-ring road, we find that the proposed indices reflect the characteristics of the road network and can express the disaster reduction performance of the districts. In addition, they can facilitate the priority of seismic retrofitting plans considering the characteristics of the district.

An earthquake of M_JMA 6.6(M_W 6.2) occurred in the central area of Tottori prefecture in Japan. Several research institutions have installed strong motion seismometers that observed large ground motions around the source fault. In this study, we tried to estimate a characterized seismic source model composed of SMGA from several observed records by empirical Green's function method. As the results, we found that the observed records can be reproduced by two SMGAs on the source fault plane. The relationship between seismic moment and combined asperity area of the earthquake agrees well with the scaling law in the previous study.

During to the 2011 off the Pacific coast of Tohoku Earthquake (the Great East Japan Earthquake) that occurred on March 11, 2011, liquefaction occurred over a large area in the Tohoku and Kanto regions. At present, the areas where liquefactions were identified extend from Aomori Prefecture in the north to Kanagawa Prefecture in the south within approximately 650-km long zone. This earthquake was characterized by the long duration of ground motion with several successive events of the source area. In this paper, firstly we examined the liquefaction occurrence ratio in terms of measured seismic intensities by geomorphologic classification units based on a dataset of strong ground motion data and observation records of liquefaction sites during the 2011 off the Pacific coast of Tohoku Earthquake to show the liquefaction potentials differing between the Tohoku and the Kanto regions. Next, in order to investigate the effect of the ground motion duration, we calculated the real-time seismic intensity and its accumulated index (ΔIs) as explanatory parameters of ground motion intensity. As a result, although it was found that there was still regionality in the Tohoku and the Kanto regions, it clarified that the large ΔIs caused to increase the liquefaction occurrence ratio.

In evaluating seismic intensity distribution maps for specified seismic source faults, several different cases of source fault model parameters are adopted in order to incorporate uncertainty associated with parameter settings. In this study, a method is proposed for evaluating spatial variation and correlation reflected in a set of seismic intensity distribution maps for different cases. The singular value decomposition technique is applied to all cases of seismic intensity distributions, through which spatial variations are derived as left-singular vectors in modal forms. Next, a simulation method for seismic intensity distributions preserving the spatial variation and correlation in original dataset is proposed. The vectors characterizing each individual seismic intensity distribution are replaced by vectors whose covariance matrix is equivalent to that for the original seismic intensity maps. A technique called "statistical preconditioning" is employed to efficiently perform such simulations. Numerical examples are shown for predicted earthquakes potentailly caused by Eastern Boundary Fault Zone of the Ishikari Lowland.

In order to support earthquake disaster BCP, the authors proposed a simple dynamic earthquake resistance evaluation method using basic information of the building, which consists of a method of estimating the load capacity coefficient and a method of predicting the damage to the building structure from the capacity spectrum method for the one-degree-of-freedom building model. However, problems such as verification of the damage prediction accuracy of a simple dynamic seismic evaluation method remained unsolved.

In recent years, environments for verification analysis that include, for example, facility information, earthquake observation records, and damage information have been prepared by publishing various building damage reports and earthquake observation records for buildings affected by the 2011 Great East Japan Earthquake. For this reason, the accuracy of damage prediction by a simple dynamic earthquake resistance evaluation method was verified using public information on 28 buildings.

Although the simple dynamic earthquake resistance evaluation method sometimes gives a slightly higher response value, the resultant damage assessment was for the most part reasonable. It was therefore confirmed that this method is effective as a screening evaluation method in seismic resistance surveys of multiple existing buildings and at the planning stage for earthquake countermeasures.

The nonlinear soil amplification model for the evaluation of response spectra is developed using strong ground motion records. This model transforms a linear amplification, which is prepared in advance at a specified site, to a nonlinear amplification according to the input level of bedrock motions. The model consists of two steps, and two functions are formulated for each step. One represents "elongation of predominant period" and the other "decrease of amplification". Functions describe a degree of nonlinearity with only one parameter, effective shear strain. According to the proposed function form, a nonlinear site amplification model for a simple two-layered ground model is made based on numerical analysis of sequential ground response. The ratios between amplifications from a proposed model and precise waveform analysis are constant and close to 1.0. On the basis of the result, it is verified that the proposed model have applicability to the evaluation of nonlinear soil amplification. Next, another model is made using strong ground motion records at K-NET Toyosato site in the northeast region of Japan. The ground of this site is considered to be almost two-layers. In the period shorter than predominant period, the amplification evaluated with the model developed in this study shows good agreement with those of previous studies. In the period longer than predominant period, the model of this study shows the increase of amplification as a result of elongation of predominant period, which the models of previous studies do not describe. It is concluded that the proposed model is useful for the estimation of the nonlinear soil amplification.

The purpose of this study is to reveal characteristics of observed ground motions and distributions of collapsed wooden houses and to analyse relationship between the characteristics and the damage of wooden houses in the 2016 Kumamoto earthquake. This paper focuses on the three areas in Kumamoto prefecture: Mashiki town, Nishihara village and Aso city, where very strong motions were observed. The observed ground motions of the main shock have two pulse periods, which are about 1 and 3 second, respectively. Next, we clarify the distributions of collapsed wooden houses in the three areas using aerial photographs. In addition, peak ground velocities (PGV) are estimated in the three areas. The estimated PGV are more than 150 cm/s in some areas in Mashiki town which suffered severe damage on the wooden houses. Finally, by seismic response analysis, it is revealed that especially short-periodic components including about 1 second of the main shock greatly contribute to collapse of wooden houses and that strong PGV is accountable for the severe damage of wooden houses qualitatively.

We evaluated the influence of nonlinear earthquake response by nonhomogeneous property value distribution model on spatially variation of seismic ground motions and foundation ground stability (minimum slip safety factor) based on numerical experiments, for ground near the building foundation. In order to make the ground that is as close to reality as possible, we used the research building of Kyoto University Nuclear Furnace Research Laboratory and its surrounding ground information where layer structure and variation of S wave velocity in the vertical direction are investigated by boring etc. Regarding the spatially variation of seismic ground motions, the nonlinear analysis of the nonhomogeneous ground model resulted in lower coherence between receiving points of the same horizontal level than linear analysis. Also, fluctuations in Fourier spectral ratio increased. Regarding the evaluation of the minimum slip safety factor of the foundation ground (nonlinear analysis), the nonhomogeneous ground model resulted in an increase in the slip safety factor compared to the homogeneous ground model. Regarding the spatially variation of seismic ground motions, we considered that the main reason was that the variation of each ground element from the initial physical property value (especially shear rigidity) became even larger, when the strong earthquake occurred. Regarding the evaluation of the minimum slip safety factor of the foundation ground (nonlinear analysis), we considered that the main reason was that the variation of the maximum shear stress aspect of each element becomes large.

We present an inference method for Green's functions for multistory torsionally coupled shear buildings, and demonstrate that it is a practical tool by an application to an existing building. We first show that horizontal vibrations of an individual floor are specified as a three-input-three-output linear system, introducing Green's functions in it. Then, we develop the inference method for discrete Green's functions by the Wiener filter. Applying the inference method to an 8-story torsionally coupled shear building, we obtain reliable Green's functions, correcting waveform deformation of Green's functions associated with the torsion. We also show that the effect of wind on Green's functions is negligibly small.

In recent years, high-rise buildings are required to possess the higher performance for earthquakes, not only for the conventional input ground motions of L1 and L2, but also for the L3 earthquake motions (maximum considered earthquake ground motions), which are the ones with a probability of once every several thousand years, such as the long-period ground motions with long-duration from a M9-class subduction-zone earthquake, and/or the near-source ground motions from large-scale active faults. As for the existing high-rise building, there have been many retrofitting cases using additional dampers, by considering only the long-period ground motions, but the near-source ground motions. Therefore, in this study, we evaluated earthquake resistance performance using additional dampers against various types and levels of input ground motions, not only for long-period ground motions, but also for the near-source ground motions. As a case study, we chose Kogakuin University Campus of the steel moment-resistance frame building with 28-stories. As for the method of arranging dampers, we used a relatively simple method of pushover analyses using a 3D structural model, and decided the arrangement of dampers based on the deformations of the stories and the dampers. As a result, we obtained an effective damper arrangement model of 44 dampers, and confirmed the validity of the model by conducting seismic response analyses using the various input ground motions.

In our previous study¹⁾, we constructed ground motion prediction equations (GMPEs) for absolute velocity response spectra from the viewpoint of earthquake early warning of long-period ground motion intensities. In the present study, we evaluated the performance of the GMPEs for seven recent earthquakes having Mw ≥ 6.5 that occurred after the construction of the GMPEs. We found that the GMPEs generally performed well for the events. Finally, we explain a methodology for the revision of site factors in the GMPEs, and discuss some implications for future study.