Extended end-plate beam-column joints in seismic moment resisting frames

Abstract

<p>Although moment resisting frames (MRFs) are the most widely used structural system for seismic-resistant steel buildings, several important aspects of their behaviour under real earthquake excitation are not well understood. One of these issues that needs to be further studied is the seismic performance of beam-to-column joints. During severe earthquakes, joints can undergo severe inelastic deformations affecting the strength, stiffness and inelastic action distribution throughout the frames. Therefore, the objectives of this study are to investigate the behaviour of beam-to-column joints, to assess the effect of the joints' response on the frame's overall behaviour and to provide guidelines and design rules for detailing the joints. In this thesis, attention was focused on studying the behaviour of bolted extended end-plate joints. This was achieved through an experimental-analytical research program. The experimental work carried out involved two phases. First, cyclic tests on full scale beam-to-column connections was done to examine the behaviour of such a connection type, together with the response of its individual components. Second, cyclic tests on full scale subassemblages were done to study the response of panel zones of this joint type. Based on the observation and results of the experimental program, analytical models to predict the behaviour of both the connection and the panel zone were developed. The sensitivity of these models was checked by comparing their predictions with the experimental results. The models were then incorporated into Drain-2D computer program to be used in analyzing MRFs. Analytical research on the dynamic behaviour of MRFs designed to allow active yielding of panel zone joints and to permit connection deformation was performed. Several steel MRF designs for an eight-storey and twenty-storey office buildings were analyzed using various ground acceleration records. Finally, design criteria for detailing the joints, i.e. the connection and the panel zone, and code recommendations to improve the performance of MRFs subjected to severe earthquakes were introduced.</p>