ESTIMATION OF SYSTEM-LEVEL DUCTILITY DEMANDS FOR MULTISTORY STRUCTURES

System-level ductility is an essential factor for earthquake resistant design of structures, It is related to the response modification fact or (Or force reduction factor), commonly used in aseismic design proce dures. The ductility demands for single-degree-of-freedom structures o r individual structural members can be determined easily, However, the re is no established method of determining the ductility demands for s tructural systems, The object of this study is to develop a method for the estimation of the ductility demand at the structural system level . The validity of the proposed method has been examined for several ca ses of different structures and different earthquake excitations. (C) 1997 Elsevier Science Ltd.