Collapse Assessment for a RC Frame Structure in Bucharest (Romania)

Abstract

The focus of this paper is to evaluate the collapse probability of a planar RC frame structure designed for the seismic conditions of Bucharest (Romania). The assessment is performed using both static and dynamic nonlinear analyses. 1000 pushover curves are sampled for the analysed structure taking into account the uncertainty due to the materials’ strengths and due to the gravitational loading. The nonlinear time–history analyses are conducted on equivalent SDOF structures derived from each sample of pushover curves. Finally, the collapse assessment is assessed through multiple stripe analyses performed using a ground motion dataset of 20 representative horizontal components recorded in Bucharest area during three past major intermediate-depth Vrancea earthquakes. The results show an annual collapse probability of the order 3.0 × 10−3 to 6.0 × 10−5, which represents a value similar with those obtained in order studies in the literature. The nonlinear analyses also show that the epistemic uncertainty due to the modelling uncertainties has a much smaller contribution to the total uncertainty as compared to the record-to-record variability. The most important parameters affecting the collapse fragility appear to be the concrete compressive strength and the Young’s modulus for concrete.