Earthquake and Structural Engineering Laboratory

Engineering, Japan

Earthquake and Structural Engineering Laboratory

Engineering, Japan
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Murono Y.,Earthquake and Structural Engineering Laboratory | Nishioka H.,Foundation and Geotechnical Engineering | Nogami Y.,Earthquake and Structural Engineering Laboratory
Quarterly Report of RTRI (Railway Technical Research Institute) (Japan) | Year: 2011

It is well known that the earthquake response of a pile-supported structure is strongly affected by dynamic soil-pile interaction. When the structure is subjected to severe ground motion, the soil behaves in a nonlinear manner. Two kinds of soil nonlinearity will affect the characteristics of dynamic soil-pile interaction. One is the nonlinearity which appears in the soil surrounding the pile and the other is the nonlinearity which appears in the free-field. The nonlinearity of soil surrounding the pile is caused by the inertia force transmitted from the superstructure onto the pile head (i.e., local-nonlinearity). Soil nonlinearity in the free-field is caused by the transmission of shear waves (i.e., site-nonlinear ity). Various tools based on the Sway-Rocking model have been developed to analyze nonlinear dynamic soil-pile interaction. Most of these methods, however, only take into account local-nonlinearity effects. Therefore, a methodology to evaluate the effects of both local-nonlinearity and site-nonlinearity are developed in the paper. The accuracy of this method is confirmed by comparing simulated and experiment results.


Toyooka A.,Administration Division | Murono Y.,Earthquake and Structural Engineering Laboratory | Nogami Y.,JR East Consultants Company | Nishimura T.,Earthquake and Structural Engineering Laboratory
Quarterly Report of RTRI (Railway Technical Research Institute) | Year: 2012

The research in this paper studies the effect of the response of upper structure and soil deformation on the overall behavior of structure through static and dynamic analyses. Several structures with pile foundations, such as bridge pier, viaduct and isolated bridge, were assumed to be constructed on a soil of good condition. The soil deposit characters were selected so that their deformations could be regarded as negligible in the design standard, whereas their shear velocity and resulting strain would change drastically with the depth. It was clarified through series of simulations that response of soils significantly affects the moment distributions of piles, regardless of the amount of response of superstructures. It consequently follows that the soil behavior should be properly considered even under good soil condition.


Luo X.,Earthquake and Structural Engineering Laboratory | Sakai K.,Earthquake and Structural Engineering Laboratory | Sogabe M.,Structural Mechanics Laboratory
Quarterly Report of RTRI (Railway Technical Research Institute) | Year: 2012

Since differential displacement of track surfaces caused by earthquakes strongly influences the running safety of trains, it is important to consider its effects for the seismic design of railway structures. In this paper, in order to obtain a proper seismic wavelength for the assessment of track differential displacement, the authors examined phase velocity characteristics which reflect the dispersion of Rayleigh waves, and proposed an empirical formula for calculating the wavelength suitable for track assessment based on sets of various real ground parameters. Moreover, the influence due to the wavelength and the characteristics of the ground on the angular rotation assessment of viaducts was examined.


Sakai K.,Earthquake and Structural Engineering Laboratory | Murono Y.,Earthquake and Structural Engineering Laboratory
Quarterly Report of RTRI (Railway Technical Research Institute) (Japan) | Year: 2011

Estimation of earthquake clusters expected to occur in a certain area together with their probability occurrence are required to evaluate the seismic risk to railway structures and vehicles. In this study, a calculation method is proposed for obtaining a set of earthquake time histories and their occurrence probabilities by combining a seismic hazard analysis and estimation of strong motion. Earthquake ground motion in the Tokyo region was then estimated using the proposed method in order to create an example of its applicability. It was then confirmed that seismic risk to railway structures and vehicles can be evaluated by using the proposed method.


Murono Y.,Earthquake and Structural Engineering Laboratory | Goto K.,International Affairs
Quarterly Report of RTRI (Railway Technical Research Institute) (Japan) | Year: 2011

A great earthquake of magnitude M9.0, occurred around 14:46 pm on March 11, 2011, at an epicenter at an undersea depth of 24 km off the Sanriku coast line, an area in the northeastern part of the main island of Japan. The earthquake was named as "2011 off the Pacific Coast of Tohoku Earthquake." A large-scale fault slide occurred at the plate boundary stretching from the offshore area of Iwate to Ibaraki, and caused heavy tremors of level 7 Japanese Seismic Intensity at Kurihara City in Miyagi Prefecture, and of level 6+ in wider areas in Miyagi, Fukushima, Ibaraki and Tochigi prefectures. This article outlines the outline of the earthquake, and gives an overview of RTRI activities to support the recovery of railway networks damaged by the earthquake. The comparisons of the actual shaking waves of this earthquake with design waves in the Design Standards for Railway Structures: Volume of Seismic Design is also described.


Murono Y.,Earthquake and Structural Engineering Laboratory | Sakai K.,Earthquake and Structural Engineering Laboratory
Quarterly Report of RTRI (Railway Technical Research Institute) | Year: 2013

Recently earthquake ground motions with high frequency components have been observed on a regular basis. It is well known that the "effective input motion" is reduced in the high frequency range due to the effect of Kinematic interaction of the soil-pile system. Dynamic soil-pile interaction analyses, therefore, were conducted by varying the conditions of both the ground and piles, and the influence of input loss from the pile foundation was investigated. The result revealed that the input loss was negligibly small in case of ground motion whose amplitude was predominantly in the 1~2 Hz range, such as the Hyogoken Nanbu earthquake. On the other hand, the input loss was quite large in the case of high frequency seismic motion such as that observed in the Tohoku earthquake. A simplified expression of input loss, which could be used in practice for seismic design and is based on the Winkler-type spring model, was proposed.


Sakai K.,Earthquake and Structural Engineering Laboratory | Murono Y.,Earthquake and Structural Engineering Laboratory
Quarterly Report of RTRI (Railway Technical Research Institute) | Year: 2013

Many aftershocks followed the 2011 off the Pacific coast of Tohoku earthquake after the main shock. There is a need to assess the seismic stability of railway facilities against large earthquakes in consideration of aftershocks. To this end prediction of aftershocks is necessary. This paper proposes a prediction method, which can calculate the magnitude and time lapses between aftershocks after a main shock, based on statistical processing on past earthquakes including aftershocks. Using the proposed method, preliminary calculations were conducted to obtain the time history for a main shock of magnitude 7.0, and its aftershocks. The effect of the aftershock on the damage to the structures was investigated using these waveform groups.


Izawa J.,Earthquake and Structural Engineering Laboratory | Murono Y.,Earthquake and Structural Engineering Laboratory
Quarterly Report of RTRI (Railway Technical Research Institute) | Year: 2014

Past studies show that soil liquefaction due to a long duration earthquake with low acceleration, for example as observed in the Tokyo Bay area in the 2011 Great East Japan Earthquake, is largely affected by liquefaction strength for a large number of loading cycles. It is, therefore, extremely important to know the liquefaction resistance for a large number of loading cycles. This paper describes the results of the hollow cylindrical cyclic torsion shear tests that were conducted to ascertain the effects of grain size distributions on liquefaction resistance for a large number of loading cycles. The test results clearly show that the tendency of a decrease in liquefaction resistance for a large number of loading cycles is influenced by mean grain size, inclination of grain size distribution, and so on. Finally, the effect of liquefaction resistance curve characteristics on the assessment of liquefaction potential is examined using the cumulative damage theory.


Murono Y.,Earthquake and Structural Engineering Laboratory | Sakai K.,Earthquake and Structural Engineering Laboratory
Quarterly Report of RTRI (Railway Technical Research Institute) (Japan) | Year: 2010

Modeling the phase characteristics of earthquake ground motion is important in synthesizing a design earthquake motion consistent with a given set of response spectra. We assume that earthquake ground motion can be expressed by a convolution of the three time functions of source, path and site effect. This paper presents a new methodology to model the phase characteristics of earthquake motion using the concept of group delay time. The group delay times of source effects caused by rupture propagation on the fault plane are theoretically calculated, while those of the path and site effects are empirically modeled from observed records using the inversion technique. We also demonstrate that earthquake motion can be synthesized based on our newly developed phase model.

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