Fragility functions for masonry infill walls in RC frames with the in-plane and out-of-plane loading

This paper presents a comprehensive analysis of masonry infill walls under both in-plane and out-of-plane loading, offering limit state criteria and fragility functions. Four distinct damage states are defined to capture damage evolution under diverse loading conditions. The research establishes a thorough database documenting in-plane and out-of-plane drift levels corresponding to each damage state, derived from experimental testing on masonry-infilled frame specimens from existing literature. Fragility functions were developed based on in-plane or out-of-plane drifts for four distinct damage states. The study systematically evaluates the influences of masonry prism compressive strength, slenderness ratio, and aspect ratio. Notably, the impact of prior in-plane damage on out-of-plane vulnerabilities is investigated. The study introduces equations designed to predict changes in the central tendency and dispersion parameters of out-of-plane drift thresholds, accounting for variations in prior in-plane drift ratios. It's crucial to highlight that the empirical fragility functions proposed in this study are exclusively based on experimental tests involving tight-fit single-leaf infill walls without openings or modifications.