APPLICATION OF TWO-DEGREE- OF- FREEDOM MODELS TO SEISMIC DISPLACEMENT DEMAND ESTIMATION

摘要

The seismic displacement demands under strong earthquake excitation of a multi-story structure with column hinge damage mechanism can not be well estimated by conventional Pushover analysis and Modal Pushover analysis. In this paper this kind of structures was equivalent to two-degree-of-freedom (TDOF) systems in Pushover analysis. The relationships of a multi-degree-of-freedom (MDOF) structure with its equivalent TDOF system were derived. Then the proposed seismic demand estimation procedure by using TDOF model was developed. Seismic response of seven planar frames with column hinge damage mechanism and one with beam hinge damage mechanism was analyzed by conventional Pushover analysis, Modal Pushover analysis, proposed Pushover analysis procedure and time history analysis. The precision and applicability of three Pushover analysis methods were compared. The results indicated that the seismic displacement demands under strong earthquake excitation of a structure with column hinge damage mechanism will be underestimated by conventional Pushover analysis and Modal Pushover analysis, but well estimated by proposed procedure.