EFFECT OF HYSTERESIS TYPE ON DRIFT CAPACITY FOR GLOBAL COLLAPSE OF MIDDLE-HEIGHT MOMENT FRAME STRUCTURES FOR SEISMIC LOADS

It is conjectured that different hysteresis behavior may lead to different levels of response because of degradation in strength and stiffness. To examine the existence and magnitude of this effect, this research aims to: 1. Determine the global collapse capacities of several classes of moment frame buildings under seismic loads. 2. Develop seismic criteria for design and evaluation of moment frame buildings that reflect and account for the global drift capacity. To achieve these objectives, seismic analyses of 9-story moment resisting frame buildings were conducted to evaluate the effects of the hysteretic behavior of beam-to-column connections, structural stiffness, and structural strength on the collapse potential. Five hysteresis models: bilinear, strength degradation, stiffness degradation, stiffness degradation + strength degradation, and pinching are evaluated. For the 9-story building, the effects of hysteresis behaviors are very significant for both global drift capacities and Sa capacities. Two interesting results are that (1) strength degradation significantly decreases both the global drift capacity and the Sa capacity, whereas, (2) the existence of stiffness degradation increases the global drift capacity by 14 % and the Sa capacity by 44 % beyond the base bilinear model. Details of the study and other results are summarized in the paper