Seismic performance of moment resisting frames with flexible joints

An analytical study was conducted to investigate the effect of joint flexibility, in particular extended end-plate joints, on the response of moment resisting frames. Eight storey frames having extended end-plate joints and with joints detailed according to different design criteria, were analysed for different earthquake records using a step-by-step time history analysis. Realistic models developed from an extensive experimental research program were used to simulate the joint response. An evaluation of the frames' performance in terms of lateral deflection, inter-storey shear, drift, and the inelastic rotational demands imposed upon the beams, columns and joints was carried out. It is concluded that joint behaviour is an important consideration in a frame's response. Also, its performance can be much improved by properly designing and detailing the joints.