Vulnerability assessment of reinforced concrete buildings at precarious slopes subjected to combined ground shaking and earthquake induced landslide

At present, the seismic vulnerability of reinforced concrete (RC) buildings standing in the vicinity of the slope's crest is assessed ignoring, in most cases, the effect of topography and the potential slope instability. This study aspires to investigate these effects by proposing a methodological framework for assessing the vulnerability of typical RC buildings subjected to combined ground shaking and earthquake induced landslide hazards. The method is based on a two-step numerical analysis procedure. First, the acceleration time histories and the permanent differential ground displacement time histories are evaluated employing dynamic non-linear analysis. Then, a series of nonlinear dynamic and static time history analyses are performed for a reference low rise, code-conforming RC frame building located at varying distances from the slope's crest to compute the fragility curves for the two loading conditions i.e. ground shaking considering topographic amplification and seismic permanent landslide displacements. The derived fragility curves, described as a function of peak ground acceleration (PGA) at the rock outcrop, are compared to provide insight into the primary damage mechanism while, in the end, coupled fragility curves are generated to account for the combined potential damages due to ground shaking and seismically induced landslide considering or not the interaction between the two hazards. The proposed coupled fragility curves could be used within a probabilistic risk assessment framework to evaluate the structural vulnerability of specific RC building typologies at precarious slopes due to ground shaking and seismically induced slope displacements.