Abstract
The ground motion response in a moderately stiff soil in seismic events has been traditionally studied based on the actual field records which, however, have yet to offer consistent results regarding the amplification effect of the ground motion. In the present study, a centrifuge model of the moderately stiff soil field is designed to study the amplification effect of the ground motion in response to seismic loads. Four El Centro waves of different strengths are used as the input wave at the base under a gravitational field of 75 g. Ground motion data at different depths are collected via a number of sensors to study the acceleration peak, time history, and response spectrum of the ground motion. The measured amplitude and energy of seismic waves are found to gradually increase from the bottom to the surface during the propagation of seismic waves, and the peak acceleration at the surface is significantly magnified. The response spectrum analysis shows that the acceleration response spectrum gradually moves to the high-frequency direction from the base to the surface and the value of the response spectrum decreases with the increase of the depth in the present study.
Highlights
Seismic field evidence has shown that the site conditions are important factors that influence the ground motion response and the seismic damage [1]
A very large part of the country can be considered to be located in moderately stiff soil sites [17]. e site conditions are typically categorized based on the soil site’s shear wave velocity in several national standards and building codes
In 1997 Uniform Building Code [14] and NEHRP [15], a site with a moderate range of shear wave velocity between 180 m/s and 360 m/s is considered as a stiff soil profile, which is lower than the hard rock, rock, and soft rock but higher than the soft soil profile, whereas a soil of such range is considered as a moderately stiff soil site in Chinese Earthquake Design Code [16]
Summary
Seismic field evidence has shown that the site conditions are important factors that influence the ground motion response and the seismic damage [1]. Several studies based on the actual field observation records have reported significantly different results about the amplification effect of ground motion in the moderately stiff site conditions [19], possibly due to the particularity of geological conditions and the uncertainty of seismic events. E present study is aimed to simulate the ground response of a moderately stiff soil site with dynamic centrifuge model testing to identify the variation of the amplification effect with depth. It is generally beneficial to avoid excessively large or tall boxes that may result in significant inaccuracies; to simulate the soil of a modest depth, for example, 30 m in the moderately stiff site, the height of the soil is designed to be 400 mm, with a centrifugal acceleration of 75 g used in the present study.
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