Influence of earthquake intensity measure on the probabilistic evaluation of RC buildings

The correct assessment of different performance levels of reinforced concrete (RC) structures still remains an unaccomplished task in the field of earthquake engineering. Starting from the expression for classical time-independent reliability formulation, and under a few established assumptions, the probability of exceeding a specified performance level can be written in a closed form via Probabilistic Seismic Demand Analysis. It has been recognized that the choice in terms of the intensity measure (IM) of a records plays a leading role in the performance assessment, because it is strongly related to the seismic hazard. The general framework for computing the probability of exceeding a specified limit state is here specialized to RC elements and implemented for different frame structures, showing a relatively computational efficiency for the range of buildings considered. The procedure is then applied using several alternative scalar ground motion IMs in order to observe the unavoidable variability of the results in terms of the computed total risk.