LARGE DISPLACEMENT EFFECTS ON SEISMICALLY EXCITED ELASTIC-PLASTIC FRAME STRUCTURES

Recently developed nonlinear beam/columns elements based on large displacement theory are easily accessible to the research community for the dynamic analysis of earthquake excited structures. It is of interest to assess whether the application of these elements is desirable in engineering practice and research. This study is intended to provide quantitative knowledge on the importance of large displacement effects on the response of seismically excited structures. Generic frame models are utilized to represent SDOF and MDOF structures. Equivalent pulses are used to represent seismic input, since their effect on structural response is comparable to that of near fault ground motions. Large displacements of frame structures give rise to second-order amplification and thus, structure and member P-delta effects are addressed. The results demonstrate that the influence of large displacement formulations is of secondary importance for the response prediction of elasticplastic SDOF and MDOF frame structures.