An LES-based fragility methodology for low-rise buildings incorporating net wind pressure and debris-induced failures

Roof systems in low-rise buildings are particularly vulnerable to wind loads, often sustaining severe damage during typhoons. Consequently, accurate hazard assessments are essential for risk mitigation. This paper presents an engineering-based fragility approach to evaluate typhoon-induced hazards on low-rise buildings. In this approach, peak wind loads are determined through Large Eddy Simulation (LES), thus avoiding inaccuracies associated with empirical formulas. The method also captures the relationship between wind loads and wind damage by incorporating windborne debris, both external and internal wind pressures, and the condition of the openings. A key advantage over existing models is its ability to assess the impact of building location and local construction features—such as eaves, parapets, and storm mitigation devices—on wind damage. As an illustrative example, this paper examines a group of buildings equipped with a typical storm mitigation device (spoiler). The results indicate that, in a regularly arranged building group, spoilers become more effective at reducing roof tile damage as the wind direction angle increases. Under lower wind speeds, spoilers on front-row buildings are the primary factor mitigating roof tile damage, whereas at higher wind speeds, spoilers on rear-row buildings have a larger influence. Additionally, for a regular arrangement, the spoiler’s ability to mitigate wind damage to building envelopes weakens as building density increases.