Non-linear Dynamic Behavior of Steel Structures with Different Bracing Systems

Based on capacity design philosophy, considering the dissipated and non-dissipated parts in structures, the behavior factor is specified in codes. according to the standard Iranian code of practice, the behavior factors for structures with different bracing systems are the same. whilst each system dissipates energy in different ways. In this research, the nonlinear dynamic behavior of structures with different bracing systems are investigated. For this propose, two dimensional frames with different types of bracing systems are designed Different time history records are applied for nonlinear dynamic analysis of the designed frames. The results indicated that the models are not satisfied the capacity design rules, the columns are failed sooner than the yielding pattern of the bracing elements and the frames can not achieve the expected ductility. To over come to these difficulties, the authors proposed the method for design of structures with diagonal bracing systems to increase ductility. All of the models are designed again according to this proposed method and analyzed for the second time. The results represented that the new models have better behavior and achieve more ductility. It is also shown that the behavior factors for these frames are significantly increased.