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Tokunaga M.,Structural Mechanics Laboratory | Sogabe M.,Structural Mechanics Laboratory | Uehan F.,Structural Mechanics Laboratory | Tanimura H.,Concrete Structures Laboratory | And 2 more authors.
Quarterly Report of RTRI (Railway Technical Research Institute) (Japan) | Year: 2012

The object of this paper is to propose a method to estimate the equivalent natural period with micro-tremor measurements on the basis of the correlation between the natural frequency and the yield frequency. A method, combining the Eigensystem Realization Algorithm and some empirical hypotheses of vibration modes, was proposed for identifying the first natural vibration modes of structures. A ratio of the yield frequency to the natural frequency was mostly a certain constant value and the average value of the ratio depends on the type of structures. This paper proposes a simple procedure for estimating the yield frequency with micro-tremor measurements.

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.

Uehan F.,Structural Mechanics Laboratory | Minoura S.,Structural Mechanics Laboratory
Quarterly Report of RTRI (Railway Technical Research Institute) | Year: 2015

The authors have been studying a method for evaluating rock slope stability by applying a non-contact vibration measurement technique. Consideration of the size of the rock block, its shape and conditions supporting it are indispensable for improving the accuracy of the evaluation method. Accordingly, an aerial survey system to observe the shape of the rock block was built. Next, software was developed to automatically generate a three dimensional finite element analysis model from the data collected relating to the shape of the block. Finally, a rockfall risk evaluation technique was proposed using the parametrical analysis results of the FE analysis model regarding loads exerted on and conditions supporting the block.

Yokoyama H.,Geology Laboratory | Izumi Y.,Architecture Laboratory | Watanabe T.,Structural Mechanics Laboratory
Quarterly Report of RTRI (Railway Technical Research Institute) | Year: 2016

The analysis of the whole model of train-induced vibration, which consists of the moving train, the track, the supporting infrastructure, the ground, and the building, is currently too large to solve. We thus proposed a numerical simulation method by combining two separate dynamic analysis models. One is an analysis model of the dynamic interaction between the moving train and the track-structure system for calculating excitation force. The other is a three dimensional dynamic analysis model of the supporting structure, the ground, and the building for calculating the propagation of vibration. © 2016, Ken-yusha Inc. All rights reserved.

Watanabe T.,Structural Mechanics Laboratory | Sogabe M.,Railway Dynamics Division | Tokunaga M.,Structural Mechanics Laboratory
Quarterly Report of RTRI (Railway Technical Research Institute) | Year: 2014

In order to analyze effectively the response of the members of a railway reinforced concrete rigid frame viaduct to the vibration, a new analysis method was developed. It divides the whole railway system into a vehicle / track model, and a track / structure model. These models were used to examine the influence of various vehicle, track and structure parameters on structural member vibration. The dominant factors were quantified for each frequency concerning the response of the center slab at a train speed of 270 km/h.

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