It is known that furniture in high-rise buildings continue to move around and collide against each other or wall due to large long-period ground motion. It is important to clarify relation between indoor damage and floor response for damage mitigation. But the relation between indoor damage and large floor response due to a megathrust earthquake is not clear yet. In this paper, the indoor damage during an earthquake in high-rise residential buildings was simulated in order to clarify the relation between indoor damage and acceleration level of floor response. As the result of the simulation, in the upper floor of high-rise buildings excited by the first mode of vibration, i) in case floor response is smaller about 200cm/s², almost furniture is not move. ii) In case floor response is about 200-300cm/s², slender furniture (Width/Height = 0.2-0.3) begins to overturn. iii) In case floor response is about 300-450cm/s², almost unfixed furniture move, but furniture is not significantly scattered because its displacements are small. iv) In case floor response is over about 450cm/s², all of unfixed furniture continue to move around and collide against each other or wall for a few minutes. Then, comparison of the simulation result with the result by the simple methods revealed that the simple methods underestimate the indoor damage in case floor response is large.

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Detailed three-dimensional FEM models have been used for seismic analysis with the growth of computer performance. In seismic analysis using the FEM models, Rayleigh damping and element Rayleigh damping have been commonly used; however, it is not necessarily clear how to model those damping in performing seismic analysis of a system consisted of structures with multiple damping properties. The purpose of this study is (i) to propose modeling method for element Rayleigh damping applied to the above-mentioned system and (ii) to examine effectiveness of the proposed method. In the proposed method, coefficients of element Rayleigh damping are determined by using weighted least-squares method, and the weighting factors are based on products of modal participation function and response spectrum of input seismic motion. Additionally, in order to examine effectiveness of the proposed method, seismic analyses were performed by using lumped-mass analysis model with the proposed method and the conventional methods. Analysis results were compared with the ones given by the strain energy proportional damping, and error rates were evaluated. As a result, average error rate of the proposed method was 6%, and that was smaller than those of the conventional methods. Thus, it is concluded that the proposed method is effective for seismic analysis of the system consisted of structures with multiple damping.

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Significant duration is a frequently-used duration index based on the time history of accumulated power of ground motions normalized to the total power. In this study, significant durations, D_5-95, D_5-75 and D_75-95, defined for 5-95%, 5-75% and 75-95% of accumulated power, respectively, are evaluated for approximately 10,000 records of strong motions observed in major 35 earthquakes with M_w=5.0-9.0 which occurred from 1996 through 2013 in Japan. Accumulated power is calculated as Euclidean norm of the three components of acceleration processed with the frequency-domain filter used for calculation of JMA seismic intensity. On this basis, empirical equations for prediction of D_5-95, D_5-75 and D_75-95 are developed as functions of such factors that are commonly employed for ground motion prediction equations. Proposed models are compared with existing ones, and the advantages of this study are addressed.

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There were a lot of damages caused by the liquefaction in younger artificial ground due to the 2011 off the Pacific coast of Tohoku Earthquake. This is considering to be the result which was affected by “effects of asing” of liquefaction strength on the grounds of different sediments of reclaimed ages. It is considered various factors for specific action on sand aging effect, but in this study, we conducted the dynamic centrifugal model tests which focused on the earthquake history. It has been evaluated the effect on the liquefaction strength caused by earthquake from analysis and comparison of differences of excess pore water pressure between in case with earthquake history and in case without one. The results of the experiment were organized by its relationship among the liquefaction strength rate, relative density and corn penetration resistance, in addition to the ratio of earthquake history and liquefaction strength. The results remarkably showed a rise of liquefaction strength by the earthquake history, but not by the corn penetration resistance. The findings of this study indicate the importance of estimating the liquefaction strength added the effect of asing, because earthquake history has a great impact on the liquefaction strength.

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We need to evaluate the underground structure properly and validate previously proposed ground structure models with the observed earthquake and microtremor motions to prevent future catastrophic disasters in urban areas. In this study, we focus to Kyoto City which lies on the Kyoto basin. We first used earthquake data observed at Fire Stations in Kyoto City and calculated the Horizontal-to-Vertical Spectral Ratios (HVRs). Based on the diffuse field theory and the Hybrid Heuristic Search Method, we identified the velocity structure at each of the earthquake observation stations. Then, from the point of view that a unified velocity structure should be used in the final three-dimensional basin model, we derived a unified velocity structure for each earthquake observation station. From the unified velocity structure we calculated the theoretical microtremor HVR based on the diffuse field theory and changed the thickness of the layers to fit the peak frequency with the microtremor HVRs observed in Kyoto City to modify the velocity structure at the microtremor observation sites. Finally, we compared the identified velocity model with the previously proposed Kyoto basin model and it showed good correspondence. Also, the simulated velocity waveform showed a very good fit with the data, so we conclude that the identification method we proposed in this study is valid for strong motion predictions of future earthquakes.

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Shrine buildings were considered to be constructed on the platforms which were mainly consisted of piled up “shicras”, stones wrapped in vegetable fiber baskets, of the ancient sanctuaries in coastal Peru. Authors reported the shicras foundations have a potential for earthquake response reduction. Each shicra exhibited rotational motion like one of the current base-isolation technologies by the shaking table test using platform-modeled specimens. This study aims to investigate repeatability and stability of the earthquake response reduction properties of old foundations with shicras so as to think about significance of old technology dating up to 5000 years ago from the view point of engineering. A complete set of shaking table tests were conducted to investigate impact and variation due to possible test parameters like randomness in production and piled up of shicras and type of shaking waves. The test results arrive following conclusions. 1) Every shaking tests of shicras foundations with different parameters exhibited earthquake response reduction effects. Variations of test results due to manufacturing of shicras and construction of shicras foundations were within 25% of the acceleration on the shicras foundation. Stable properties of shicras foundation in earthquake response reduction were observed by the shaking table test. 2) In case of sine waves input, ratio of the acceleration on the shicras foundation to that on the shaking table reduces in proportion to increase of acceleration on the table due to the rotational motion of each shicra. When the accelerations on the shaking table were 4.0m/s² and 6.0m/s², average response acceleration on the shicras foundation were 3.05m/s² and 3.8m/s², which were 76% and 63% in reduction, respectively. In case the acceleration on the shaking table increased beyond 6.0m/s², the response acceleration on the shicras foundation never exceeded 4.0m/s². 3) In case of earthquake waves input, the accelerations on the shicras foundation were 40 to 80% of those on the shaking table. These indicate remarkable reductions obtained compared to the case of sine waves. Since the shicras foundations of the ancient sanctuaries experienced many events including earthquakes for their long-time existence, and they derived from natural materials which have no impact on the earth environment, there may be lessons we should learn from the old technologies. Hereafter, research progresses on this matter are expected by cooperation with archaeology and humanities. Change of human view for technologies will bring out a trend of viewpoint for future technologies which we s hould have. Much progresses of this field are expected.

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We constructed ground motion prediction equation (GMPE) for absolute velocity response spectra in the period range of 1 to 10 s with the primary aim of providing early warning of long-period ground motions in Japan during moderate to large magnitude earthquakes. We found that the spatial variability of the observed long-period intensities can be reproduced in broad areas within a difference of one intensity by using the methodology proposed in this study that requires the magnitude and distance to be determined promptly.

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This paper reports and examines the coordination activity of international urban search and rescue (USAR) teams, which were deployed to the Nepal earthquake in April 2015. The revised INSARAG Guidelines, which include new methodologies such as sectorisation and marking, was endorsed just before the earthquake in Nepal, and this paper will look at how these methodologies were applied in response to the Nepal earthquake based on the authors' experience in the field. Through the discussion, this paper considers “Disaster Literacy” that international USAR experts should have.

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This paper proposes a method to predict the acceleration response spectrum of ground motion for crustal earthquakes in probabilistic manner, which can be used for probabilistic seismic risk assessment considering simultaneous occurrence of damage for spatially-distributed multiple structures. First, statistical prediction equations of acceleration response spectra are developed by using observed records of crustal earthquakes occurred in Japan, taking into account the effects of deep subsurface soil structure. Then, inter-period correlation is modelled for inter-event and intra-event residuals. The characteristics of spatial correlation of intra-event residual are also analyzed and modelled. Finally, examples of application are shown to demonstrate the necessity of the proposed method.

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A method has been proposed for evaluating bracketed and uniform durations of long-period ground motion intensity scale based on Euclidean norm of two horizontal components of absolute velocity response. The results are represented as duration spectra. An envelope required for evaluation of uniform duration is derived by applying peak-hold method using time window with half width of natural period. Numerical examples are shown. The relationships between bracketed/uniform durations, amplitude level and predominant period are discussed.

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