American Society of Civil Engineers

Analysis of Infinite-Strip–Shaped Base Isolator with Elastomer Bulk Compression

by Michel S. Chalhoub, (Sr. Member of Tech. Staff, Engrg. Dept., The Ralph M. Parsons Co., 100 W. Walnut St., Pasadena, CA 91124) and James M. Kelly, (Prof. of Civ. Engrg., Univ. of California, Berkeley, CA 94720)

Journal of Engineering Mechanics, Vol. 117, No. 8, August 1991, pp. 1791-1805, (doi:

     Access full text
     Permissions for Reuse  

Document type: Journal Paper
Abstract: Multilayered elastomeric bearings are a basic component in base isolation systems. Several design formulas that have been developed and used in the past consider the elastomer as incompressible. In this paper, the effect of bulk compressibility is included, and the governing equations for the hydrostatic pressure in the elastomer are developed and solved for a pad with a long, rectangular cross section. The resulting expressions are simplified and recommended for the design of elastomeric bearings. The formulas that include the effect of bulk compressibility predict the real behavior of such bearings more accurately than the conventionally used ones. The compressive and flexural stiffnesses of a rubber pad and the pressure distribution on its loaded surface depend on the bulk compressibility of the elastomer, and this dependence is more significant for larger shape factors.

ASCE Subject Headings:
Base isolation