MODAL SUPERPOSITION METHOD FOR DYNAMIC ANALYSIS OF STRUCTURES EXCITEDBY PRESCRIBED SUPPORT DISPLACEMENTS

The conventional method for dynamic analysis of structures subjected t o support excitation requires support acceleration as input. In this p aper, a modal superposition method using support displacement as input is proposed and its accuracy is investigated. To determine an accurat e structural response, a static correction term representing the contr ibution of neglected high-frequency vibration modes must be added to t he modal superposition result. The proposed method is suitable for bot h uniform support excitation and multiple support excitation. Associat ed numerical integration schemes to compute the Duhamel integral for d isplacement input functions are also studied. The structural response is shown to be the same if calculated using either the proposed method for displacement input or the conventional method. (C) 1998 Elsevier Science Ltd. All rights reserved.