Analytical investigation of P-Delta effects in medium height steel moment resisting frames under seismic loading

Abstract

An analytical investigation of the P-delta effects in medium height steel moment resisting frames to selected earthquake motions was undertaken. The frames with various design drifts and fundamental time periods were designed according to the load provisions for New Zealand seismic risk zone A and to the requirements of Draft Code of Practice for General Structural Design and Design Loading for Buildings, DZ4203. The study was carried out using a two-dimensional non-linear dynamic analysis computer program. The effects of strength degradation and vertical acceleration were investigated. Dynamic magnification factors for the member forces and displacement were also observed. The limits of the maximum plastic hinge rotation, inelastic drift, curvature ductility, displacement ductility and prediction of maximum plastic hinge rotation based on the inter-storey drift were suggested. The satisfactory drift limit is recommended and suggestions for further research are put forward.