Nonlinear seismic vulnerability evaluation of irregular steel buildings with cumulative damage indices

Measuring structural damage during earthquakes has always been a challenging problem for earthquake engineers. Various damage indices are proposed with the objective of quantifying the structural damage in prototype and model structures subjected to seismic excitation. In this study, seismic vulnerability of irregular steel buildings is assessed in three dimensions considering effects of the panel zone, which has not been considered in recent studies of the field of seismic vulnerability. The buildings are modeled with different storeys and irregular plans. Seismic performance of buildings was assessed in life-safety and collapse-prevention levels. Cumulative functions of damage indices are applied in the nonlinear dynamic analysis of buildings in the near-field ground motions. It is concluded that participation rates of deformation and energy in the damage of irregular buildings are 74.5% and 25.5%, respectively. Severe damage and collapse due to seismic dissipated energy occurred in the initial storeys of low-rise buildings and in the middle storeys of high-rise buildings.