NONLINEAR DYNAMIC ANALYSIS OF MULTIPLE BUILDING BASE-ISOLATED STRUCTURES

In long base isolated buildings the superstructure may consist of seve ral parts separated by narrow thermal expansion joints. In such cases, neighboring bearings which support adjacent buildings am connected to gether at their top so that they form a common isolation and prevent i mpact at the isolation level. The analysis of such buildings constitut es the problem of a multiple base-isolated structure with a common bas emat and isolation system. This situation can not be analyzed with the existing algorithms which are capable of analyzing only a single base -isolated structure. The torsional characteristics of the combined sys tem are different than those of individual buildings on individual iso lation systems. Hence, the combined system of several buildings on a c ommon isolation system needs to be analyzed in its entirety rather tha n analyzing each building with its isolation system separately. In thi s paper an analytical model and an algorithm to analyze multiple build ings on a common isolation system am presented. Verification of the ac curacy of the algorithm by comparison with results obtained using a ge neral purpose finite element program am presented. A multiple building base-isolated structure is analyzed and the results are used to demon strate the importance of analyzing the combined system as against anal yzing individual buildings.