The effect of masonry infills on the seismic response of a four storey reinforced concrete frame—a probabilistic assessment

A relatively simple probabilistic approach for the seismic performance assessment of building structures combines the SAC-FEMA method, which is part of the broader PEER probabilistic framework and permits probability assessment in closed form, with the N2 method. In this approach, the most demanding part of the PEER probabilistic framework, i.e. the Incremental Dynamic Analysis (IDA), is replaced by the much simpler Incremental N2 (IN2) analysis. Predetermined default values for dispersion measures are needed for the practical implementation of this approach. In the paper, the simplified approach is summarized and applied to the seismic performance assessment of three variants of a four storey reinforced concrete frame: a bare frame and two frames with masonry infill, one with openings and the other one without them. The probabilities of exceedance of selected limit states are estimated and discussed. The results of the analyses indicate that the probability of failure of the infilled frames with regularly distributed infill is smaller than that of the bare frame. The beneficial effect of the infill is more evident in the probabilistic analysis than in the deterministic analysis. Of the two infilled frames, the one with openings in the infill has a higher probability of failure.