Earthquake-induced loss and downtime of seismically enhanced RC dual wall-frame buildings in Chile

Abstract

As evidenced during the 2010, 2014, and 2015 seismic events, Chilean reinforced concrete (RC) buildings have experienced earthquakes with Mw of 8.0 and higher with limited structural damage and apparently moderate recovery times. However, there is still limited research quantifying the actual seismic risk of Chilean RC buildings, especially in life-cycle terms. This study is a first step to quantitatively assess the performance of modern high-rise RC dual wall-frame office buildings in terms of expected direct economic losses and expected recovery times (i.e., downtime). As a benchmark study case, a 16-story archetype building located in Santiago on stiff soil was considered. Three design strategies to potentially improve the building’s seismic performance were explored: i) incorporating fluid viscous dampers (FVDs) in the lateral load-resisting structure, ii) employing enhanced non-structural components (ENCs), and iii) a combination of both strategies. First, the probabilistic structural responses were estimated by incremental dynamic analyses over three-dimensional nonlinear models of the archetypes utilizing sets of hazard-consistent Chilean subduction ground motions. For the loss assessment, FEMA P-58 time-based assessment was conducted to evaluate the expected annual loss and life-cycle cost for each strategy. For the downtime assessment, a novel probabilistic framework, built on the FEMA P-58 methodology and the REDi guidelines, was employed to predict the building’s temporal recovery trajectory, robustness, and rapidity considering shelter-in-place, reoccupancy, and functional recovery target recovery states. Results revealed that the archetype equipped with FVDs exhibits lower repair costs in terms of expected annual loss. On the other hand, the archetype with enhanced non-structural components shows slight reductions in economic losses. Moreover, the archetype equipped with FVDs reveals lower downtime metrics than the conventionally designed archetype. Finally, these results indicate that seismically enhancing Chilean RC dual wall-frame buildings with seismic protection systems, such as fluid viscous dampers, achieve higher levels of resilience. However, further studies will be needed considering RC buildings with different heights, seismicity levels, and soil types.