Seismic collapse risk of reinforced concrete tall buildings in Istanbul

Abstract

This study applies the latest probabilistic performance-based earthquake engineering tools in terms of nonlinear dynamic analyses in tandem with hazard-consistent record selection to assess the risk of collapse of RC tall buildings in the Istanbul metropolitan area and to quantify their seismic safety margin with respect to acceptable risk levels. Statistically representative archetype buildings selected from an extensive inventory form the basis for this assessment study. Accordingly, we chose five hypothetical building sites in Istanbul where tall buildings are densely populated to estimate the risk of collapse for 5\u2009×\u20095\u2009=\u200925 building-and-site specific cases. The results showed an average 10% probability of collapse under the ground-motion intensities with 2% probability of exceedance in 50 years. The mean annual rates of collapse range between 0.1\u2009×\u200910–4 and 6.1\u2009×\u200910–4 with an average of 1.7\u2009×\u200910–4, which remains below the tolerable risk threshold value of 2.0\u2009×\u200910–4 envisioned by the FEMA’s Building Seismic Safety Council. However, 36% of the analyzed cases yielded collapse rates higher than this tolerable risk. Among the considered cases, the core walls and frame building was identified as the best design choice from a collapse safety point of view while the tunnel form archetype raised concern by exhibiting substantially higher collapse risk compared to other archetypes.