Wind vulnerability analysis of standing seam roof system considering fatigue damage

Fatigue failure is a common failure mode of roof systems in wind disasters, therefore, it is necessary to consider fatigue damage in the wind vulnerability analysis of roof systems. To evaluate the wind vulnerability of a roof system while considering damage, a dynamic numerical simulation of the roof system with an optimised load cycle is proposed herein, based on the principle of damage equivalence. For this purpose, a damage constitutive model of the material was used in simulations, which was then verified experimentally. Second, the wind uplift failure process of the roof system was analysed in combination with the simulation and test results. The results revealed that the wind uplift failure process of the roof system conformed with the characteristics of a three-stage failure. Furthermore, values of the damage variable D corresponding to the abovementioned failure stages were measured for 90 numerical cases. Using these average values of the damage variable D as the standard, the three-stage performance levels of the roof system were quantified. Notably, values of the damage variable D corresponding to the three-stage performance levels of the roof system were 0.2, 0.62, and 1.0. Lastly, considering the uncertainty of the material parameters and wind load, a vulnerability analysis of the five types of standing seam roof systems was performed. Based on the vulnerability curve, Model 1 exhibited the lowest vulnerability, whereas Model 4 showed the highest vulnerability. Considering evident differences in the vulnerabilities of different types of roof systems can afford additional choices for engineering designs. In addition, a comparison of the wind vulnerability curves for the roof system under static and cyclic loads indicated that the wind vulnerability of the roof system under cyclic loads was significantly worse.