Assess the vulnerability of an ideal plan-asymmetric concrete structure with single-story using fragility curves and surfaces

Studies conducted on the effect of earthquakes in concrete structures are based on the structure's behavior versus these stimulations by common regulations generally. In the desired structural model, the shear walls are considered as lateral resistance elements, and considering the stiffness and strength assigned to these elements, the torsional and displacement responses are investigated. Finally, the vulnerability of structures by using fragility curves and surfaces and changing the centers of stiffness and strength relative to the center of mass and creating 7 different modes are discussed. Furthermore, the nonlinear incremental dynamic analysis (IDA) method has been used by OpenSees software. In total, 21 earthquake records, which are mostly based on FEMA P695 criteria, are employed for this analysis. The results indicate if stiffness and strength centers are located on both sides of the center of mass, which is called the symmetric model in this study, the minimum torsional response and, consequently, the least structure probability of damage is created. Also, for models that have asymmetry of stiffness and strength centers to the center of mass (asymmetric models), torsional responses, displacement, and consequently vulnerability increased at lower spectral acceleration. The proximity of stiffness and strength centers to stiff (left) or soft (right) edges and considering performance levels causes a change in the vulnerability of one edge relative to the other edge. Due to the overlap of some of the graphs obtained through fragility curves, using the fragility surfaces results to represent the extent of probability of damage more accurately was on the agenda.