91-0014 3D-BASIS-M: Nonlinear Dynamic Analysis of Multiple Building Base Isolated Structures P.Tsopelas, S.Nagarajaiah, M.C.Constantinou, A.M.Reinhorn 1991 University at Buffalo 208 PB92-113885 15 Over the last few years, a special purpose computer program, 3D-BASIS, has been developed for the dynamic analysis of base isolated building structures. This program was described in NCEER reports 89-0019 and 91-0005. In this report, 3D-BASIS is extended to the case of multiple buildings with a common isolation basemat, while retaining other features of 3D-BASIS. The program is called 3D-BASIS-M and its development and verification are presented herein. Also included in this report are the User's Guide, Input-Output printout of a case study considered in the report, and the source code for easy reference. Base Isolation, Single Building Superstructures, General State Hospital, Mesologgi, Greece, Computer Programs, Long Buildings, 3D-BASIS, Secondary Systems, Passive Protective Systems, and 3-D-BASIS-M.