Thermal-mechanical coupling analysis of membrane surface failure of the air-supported membrane structure under fire considering weld seams

Abstract

The membrane surface failure by developing a tear in air-supported membrane structures under fire conditions affects the deflation and collapse of the structure. However, in most existing studies, the failure is evaluated only according to whether the membrane surface temperature reaches the burn-through temperature of the membrane materials, without considering the effect of internal pressure variation caused by fire, and there have been even few studies on the impact of weld seams on membrane surface. This paper introduces the simplified constitutive models for PVC membranes and weld seams and a numerical simulation method to analyze the stress on the membrane surface of air-supported membrane structures during fire, taking into consideration the coupling effect of high temperature and internal pressure change. Numerical responses and the results of the full-scale fire test case by HIT (Harbin Institute of Technology) team are compared to demonstrate the effectiveness and applicability of the proposed material models and the simulation method. The study shows that the weld seams are the weak parts of the membrane surface under fire. The membrane surface failure may not first occur at the maximum temperature point of the membrane surface and the initial failure temperature is much less than the burn-through temperature of the membrane materials. Moreover, the initial failure of membrane surface should be attributed to the coevolutionary results of the stress field on the membrane surface and the degraded material properties at elevated temperatures. If the temperature is the only index to determine membrane surface failure in the air-supported membrane structure under fire, the common reference failure temperature should be reduced (approximately 120 ℃ for weld seams and 140 ℃ for membranes). The present study is valuable for fire risk assessment, performance-based fire protection design, and coupled analysis of fire and wind disasters in membrane structures.