Fragility functions for reinforced concrete framed buildings subjected to earthquake-induced landslide hazard

Post-earthquake reconnaissance missions have demonstrated that secondary events of earthquakes frequently cause even more losses than ground shaking. In the case of earthquake-induced landslides, fragility models have been recently proposed for two-dimensional reinforced concrete (RC) framed systems subjected to slow-moving earth slides, considering buildings standing close to the slope’s crest. In this paper, novel fragility models for three-dimensional RC framed buildings subjected to seismically triggered landslides are presented. Two-storey buildings were assumed to be located downstream of the slope and threatened by flow-type landslide hazard. Fragility analysis was carried out by assuming probability distributions for a number of random variables (RVs) and generating one thousand realizations of both the landslide load and building structure, according to Monte Carlo simulation method. Uncertainties in landslide load included the width and impact angle with respect to the building façade. Uncertainties in geometry, material properties and capacity models of the structure were taken into account. For each simulation realization, the structural system was analysed in OpenSees under seismic loading and landslide impact. The peak ground acceleration (PGA) and impact velocity were considered as intensity measures of ground shaking and landslide impact, whereas the maximum inter-storey drift ratio was assumed as engineering demand parameter to identify the attainment of a prescribed damage level. Fragility curves highlight that the conditional probability of collapse given PGA significantly increases if cumulative damage to the RC structure due to ground shaking and landslide loading is considered. This can have strong impact on disaster risk assessment and mitigation.