Damage estimation in reinforced concrete buildings from induced earthquakes in Brazil

Abstract

Large reserves of unexploited shale gas in Brazil have recently been reported, some of them located near densely populated cities. Obviously, the possibility for commercial exploitation of these resources has suddenly arisen, although such activities have been found to be correlated with the occurrence of induced earthquakes in other parts of the word. As in many other countries, in Brazil, making provision for the eventual effects of induced seismicity was not a consideration when the seismic standards were developed. Today, we do know about the possibility of induced earthquakes occurring, but the knowledge about the potential extent of the resulting damages remains imperfect, at best. Consequently, studies such as the one presented here, and another recently completed, are a first step to improve the knowledge base of the potential risk of induced earthquakes in Brazil for devising adequate risk-control mechanisms. This study assesses the probabilistic response to induced earthquakes of prevalent low-rise engineered reinforced concrete buildings in Brazil. Fragility functions are developed, considering structural and non-structural damage, and including the structural contribution of masonry infills. It was found that, when infill walls do not work as structural components, structural damage is more likely to occur, and conversely, when they do, non-structural damage is significant. The latter effect is produced by the reduction of the natural period of vibration, which exacerbates damage on interior components sensitive to floor acceleration. The likelihood of non-structural damage is not negligible and thus should be considered by decision makers.