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http://dx.doi.org/10.5000/EESK.2012.16.1.001

Reduction Factor for the Site Coefficient of a Building built on a Poor-backfilled Embedded Foundation  

Kim, Yong-Seok (Mokpo National University)
Publication Information
Journal of the Earthquake Engineering Society of Korea / v.16, no.1, 2012 , pp. 1-12 More about this Journal
Abstract
In this paper, the reduction factors to calculate the site coefficients of an embedded foundation are estimated, considering the effect of a poor backfill for the seismic design of a building built on an embedded foundation. This is determined by utilizing in-house finite element software, P3DASS, which has the capability of horizontal pseudo 3D seismic analysis with nonlinear soil. The 30m thick soil on stiff rock was assumed to be homogeneous, elastic, viscous and isotropic, and equivalent circular rigid foundations with radii of 10-70m were assumed to be embedded 0, 10, 20, and 30 m in the soil. Seismic analyses were performed with 7 bedrock earthquake records de-convoluted from the outcrop records; the scaling of the peak ground accelerations were to 0.1 g. The study results show that the site coefficients of a poor-backfilled foundation are gradually reduced as the foundation embedment ratio increases, except in the case of a small foundation embedded deeply in the weak soft soil. In addition, it was found that the deviation of the site coefficients due to the foundation size was not significant. Therefore, the typical reduction factors of an embedded foundation with poor backfill are proposed in terms of the shear wave velocity and site class. This is in order to find the site coefficients of an embedded foundation by multiplying the reduction factor by a site coefficient of a surface foundation specified in the design code. They can then be interpolated to determine the intermediate shear wave velocity.
Keywords
Poor-backfill; Embedded foundation; Site coefficient; Reduction factor; Finite element software of P3DASS;
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Times Cited By KSCI : 3  (Citation Analysis)
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