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Civil-Comp Proceedings
ISSN 1759-3433
CCP: 88
Edited by: B.H.V. Topping and M. Papadrakakis
Paper 128

Finite Element Modelling of a New Earthquake Protection Method Involving Soil-Structure Interaction

S.H. Lo1, X. Xu1, H.H. Tsang1 and M.N. Sheikh2

1Department of Civil Engineering, University of Hong Kong, Hong Kong
2School of Civil, Mining and Environmental Engineering, University of Wollongong, Australia

Full Bibliographic Reference for this paper
S.H. Lo, X. Xu, H.H. Tsang, M.N. Sheikh, "Finite Element Modelling of a New Earthquake Protection Method Involving Soil-Structure Interaction", in B.H.V. Topping, M. Papadrakakis, (Editors), "Proceedings of the Ninth International Conference on Computational Structures Technology", Civil-Comp Press, Stirlingshire, UK, Paper 128, 2008. doi:10.4203/ccp.88.128
Keywords: earthquake, protection, seismic, isolation, soil, structure, interaction, rubber, tyre, QUAD4M.

Traditionally, seismic isolation is defined as a flexible or sliding interface positioning between a structure and its foundation for the purpose of decoupling the motions of the ground from that of the structure, thereby reducing earthquake damage to the structure and its contents. In recent years, novel seismic isolation methods have been proposed, of which the flexible or sliding interface is in direct contact with geological sediments and the isolation mechanism primarily involves geotechnics.

To evaluate the feasibility and effectiveness of those traditional seismic isolation methods, an ordinary structural analysis package is adequate for modelling the dynamic response behaviour of the isolation systems as well as the structural response. However, the evaluation of those novel geotechnical seismic isolation methods is not as straightforward, as they normally involve the interaction of the superstructure, substructure as well as geological sediments. Hence, the ordinary structural analysis package is considered not adequate for such purpose, and another type of computer program is needed. It is particularly important if the nonlinear behaviour of soil materials has to be taken into account.

This paper firstly presents one of those novel seismic isolation methods that involves the use of rubber-soil mixtures (RSM) [1]. RSM has been proposed to be placed around the foundation of a structure for absorbing seismic energy with a function similar to that of a cushion. The low cost of this proposed seismic isolation method can greatly benefit developing countries where resources and technology are not adequate for earthquake mitigation with well-developed, yet expensive, techniques. The feasibility of using the two-dimensional finite element program QUAD4M for evaluating the performance of this new method has been demonstrated through a series of numerical simulations. A parametric study has also been carried out to test the robustness of using the program and the isolation system.

Generally, it was evident in all cases that the proposed method can effectively reduce ground accelerations, both horizontal and vertical. On average, the peak ground acceleration can be reduced by 60-70% for horizontal motion and 70-80% for vertical motion. It is noteworthy that the vertical acceleration could not be reduced by all conventional seismic isolation schemes. This is a unique advantage of the proposed method using RSM.

H.H. Tsang, "Seismic isolation by rubber-soil mixtures for developing countries", Earthquake Engineering and Structural Dynamics, 37(2), 283-303, 2008. doi:10.1002/eqe.756

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