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C. Adam:
"Evaluation of P-Delta effects in non-deteriorating MDOF structures from equivalent SDOF systems";
Talk: 13th World Conference on Earthquake Engineering (13 WCEE), Vancouver B.C., Canada; 2004-08-01 - 2004-08-06.

This paper addresses the assessment of destabilizing effects of gravity, usually referred to as P-Delta effects, in highly inelastic structures when subjected to seismic excitations. The proposed approach is based on an equivalent single-degree-of-freedom (ESDOF) system of the actual building. Appropriate properties of the ESDOF system are defined, based on results of a corresponding global pushover analyses. P-Delta effects are incorporated via an auxiliary backbone curve, which is rotated by a uniform stability coefficient. The procedure is evaluated for several multistory generic frame structures. The collapse capacity of these structures is derived from a set of Incremental Dynamic Analysis (IDA) studies involving 40 ground motions whose intensity is increased until P-Delta instability occurs. The results are translated from the ESDOF domain into the domain of the multi-degree-of-freedom (MDOF) system, and utilized for the estimation of P-Delta effects in MDOF structures. "Exact" results are contrasted with outcomes of the analyses utilizing ESDOF systems. Assumptions and limitations of the ESDOF system approach are discussed. The emphasis is on the level of response at which the structure approaches dynamic instability (sidesway collapse).