Assessment Seismic Performance of Buildings with Shear Walls trough Incremental Dynamic Analysis (IDA

During severe earthquakes Majority of structures enter the plastic range and show nonlinear behavior. Hence for Seismic performance assessment of structures more accurately, a powerful nonlinear analysis method is required in order to precise analysis of structural model and evaluating seismic demand and capacity. Incremental dynamic analysis (IDA) is the most accurate method for the assessment of the behavior of structures under seismic loads and is widely used by the majority of researchers. Also this approach is used in recent seismic guidelines. The goal of design criteria of structural codes is maintaining life safety of occupants in buildings with providing an appropriate safety margin against the collapse of structures during severe earthquakes. Using IDA procedure and new methods of seismic performance assessment, efficiency of designee codes requirements can be examined. In this study seismic performance of reinforced concrete structures with shear walls using IDA analysis method is investigated. Three reinforced concrete structures with 4, 10 and 15 story located in very high seismic hazard areas are considered. Seismic lateral force resistance of structures is provided by combination of moment-resisting frame and shear walls. These structures were designed based on ACI318-11 code for maximum considered earthquake (2475 years return period) and then the structures were modeled and nonlinear dynamic analysis was performed using OpenSees. Seismic performance of the structures using the results of analysis and based on FEMA P-695 Methodology is evaluated. Collapse capacity and safety margin of structures against collapse was estimated and also collapse fragility curves of structures was drawn. Obtained results show that reinforced concrete structures with combination of intermediate moment-resisting frame and special shear walls can be safe against collapse in severe earthquakes, although the level of safety provided by code is not equal for all of investigated structures and increasing the height of structure the level of safety is reduced and probability of structural collapse increased. For example, cpllapse probability of 10 and 15 story structures compared to 4 story one increase 60% and 80%, respectively