Collapse fragility models for unreinforced masonry buildings under flood and flow-type landslide actions

Abstract

Recent lessons from heavy rainfall-induced flood flows and flow-type landslides have demonstrated that buildings can sustain significant damage or even collapse at higher flow intensities. Unreinforced masonry (URM) buildings are particularly vulnerable, as the failure of one loadbearing wall directly exposed to flow actions may lead to the complete collapse of the structure. This underscores the urgent need to better understand the flow vulnerability of these structures. This study thus conducts a probabilistic structural collapse assessment of vulnerable URM buildings under flood flow and flow-type landslide actions using a proposed incremental flow analysis approach. After selecting two case studies from the literature, finite element (FE) models were first built and subjected to incremental flow analyses to assess their collapse levels, which were then validated against the reported results. Next, these validated modeling and analysis approaches were used to create a set of FE case models representative of typical one- or two-story URM building stocks in Europe. Comprehensive parametric simulation studies were then conducted on these case models to investigate how variations in key hazard and structural parameters influence their collapse performance under different types of physical flow actions, including hydrostatic, hydrodynamic, and debris-impact loads. Using a logistic regression approach on the simulation data, collapse fragility models were subsequently developed. The proposed fragility models are based on validated FE modeling and analysis approaches, which consider different flood or flow-type landslide scenarios while systematically incorporating associated uncertainties; therefore, they can provide reliable predictions of collapse performance for URM buildings under flow actions.