INVESTIGATION OF DETERIORATION BEHAVIOR OF HYSTERETIC LOOPS IN NONLINEAR STATICANALYSIS FOR SCMR FRAMES WITH SHEAR WALL

One of the shortages of pushover analysis is that it approximately considers the effects of deterioration pertained to hysteretic loops for structural elements. To evaluate this effect, it is necessary to perform nonlinear static and dynamic analyses and compare the results. To this end, six different planar frames, each one being a part of three-dimensional designed structures, have been modeled in OPENSEES software. All of the structures are the same in plan and different in height. Deterioration behavior as well as non-degrading behavior is considered in time history analyses. Also twelve ground motion records which are scaled to 0.35g hazard level have been used. For modeling the structural elements, stresses and strains for each designed section are considered with respect to confinement effects. The required backbone curve includes cracking, yielding and ultimate stress points which are all derived from USC-RC software, and of course with considering elements cross section, arrangement, number and size of reinforcing bars. For accurate calculation of the target displacement and bilinear idealization of capacity curve, a computer program was developed in MATLAB environment to determine the target displacement, strength ratio (R) and etc. Finally maximum displacement amounts derived from inelastic dynamic analyses for 0.35g hazard level arecompared with those obtained from nonlinear static analyses. Results show that with increasing the height of frame, the variance between frame displacements with both deteriorating and non-degrading behavior will be decreased, so that the effect of deterioration behavior could be neglected in target displacement calculation for high-rise frames.

Keywords:

Deterioration Behavior , Nonlinear Static Analysis , Special Concrete Moment Resisting Frame (SCMRF) , Shear Wall , Target Displacement