Drift-based fragility assessment of masonry infills

Masonry infills represent one of the prevailing types of non-structural elements in buildings of both Western and Eastern modern architecture. Recent seismic events have provided evidence that damage on masonry infills can lead not only to large economic losses but also to significant injuries and even fatalities. The estimation of damage of such elements and the corresponding consequences within the Performance-Based Earthquake Engineering (PBEE) framework, requires reliable fragility curves. Although there is an important body of work on testing masonry infills, there is very limited work that has led to the definition of fragility functions. This contribution presents drift-based fragility functions developed for in-plane loaded masonry infills, derived from a comprehensive experimental dataset gathered from current literature, comprising 152 specimens of infilled RC or steel frames tested under lateral cyclic loading, with different types of masonry blocks. Three key damage states associated with the structural performance and reparability of infill walls have been defined. In particular, four sources of uncertainty are evaluated: specimen-to-specimen, finite-sample, measured mortar compression strength and prism compression strength, presence of openings. The fragility curves developed in the present study are very useful for estimating damage and expected earthquake-induced economic losses for infilled buildings, by employing recently proposed methodologies based on aggregating the estimated damage at the component level for a specific structure.