Study On Behaviour Of Extended End-Plate Joints Under Load In Steel Structures

Connection in steel structures is divided into three types by rotating rigid: rigid connection, semi-rigid connection and ideal pin connection. The extended end-plate connections is fit for installation and orientation, so it has been widely adopted in practice. Duing to high stiffness, the joint is frequently regarded as rigid connection. But results from studis of R.Hansan and N. Kishi have shown that only when the initial stiffness of connection is more than 105.05 KN-m/rad, the joint is considered as rigid connection, otherwise it should be dealt with semi-rigid connction.From the Northridge earthquake and the Kobe earthquake, it is found out that the rigid connections of beam-to-column have poor ductility and result brittle fractures easily. But proper design of the end-plate connection has good ductility and can be subjected to severe earthquake.This paper,by means of experimental study and finite element analysis, investigates the behavior of the extended end-plate connections under static loading, cyclic loading and moment-rotation curves. The main scopes of this paper includes:1. Three kinds of bolted extended end-plate connections are tested.A series of parameters representing connections behavior are investigated and compared between the three types of connections.2. The paper studies the effect of end-plate to initial connection stiffness, ductility failure of beam, strength of panel zone and contactstates itself through analysis of different thickness of end-plate in the extended end-plate connection.3. Evaluations of seismic behavior of connection are drawn by studyingthe hysteretic behavior of the connections under cyclic loading.4. Through theoretically analyzing of moment-rotation curve of connection and seismic ductility of structure, the paper summarizes four parameter moment-rotation curve model and ductile designing methods.The main conclusions are as follow:1. Based on the experiments and tested results, failure models and rules are studied.2. The effect of end-plate to initial connection stiffness and contact stress itself is obvious, but the effect to contact states may be neglected.3. Analyzing the effect of failure modes to ductility of connection. Studies have show that designing both the beam and the panel zone to participate effectively in dissipating the earthquake input energy is the appropriate failure mode.4. The moment-rotation-curves model has four physically explicit parameters and it may be useful for the appilication of this connection.