Effect of Wrinkling on the Bearing Capacity of Inflated ETFE Membranes

Abstract

Inflated membranes are flexible structures and very sensitive to wind load. Wrinkling deformation of the enveloping membrane can further intensify the trend of wind-induced damage. This paper aims at studying the effect of wrinkling deformation on the bearing capacity of inflated membranes under wind. The wrinkling model based on the stability theory of plates and shells is adopted to consider the effect of wrinkling deformation. The air-membrane interaction is also included by treating the internal air as a kind of potential-based fluid. The wind load is simplified as a uniformly distributed pressure or suction on the top membrane. Both geometrical and physical nonlinearities of the membrane are considered. The finite element model of an ETFE (Ethylene-Tetra-Fluoro-Ethylene) cushion is then developed to analyze the effect of wrinkling deformation on the bearing capacities of inflated membranes under wind load for different influencing parameters such as initial internal pressure, side length, rise-to-span ratio. The results indicate that (a) Wrinkling deformation has a great effect on the failure mode and its transition, and can significantly decrease the bearing capacity as well; (b) Bearing capacity increases with the initial internal pressure and side length when determined by the instability failure, and decreases when determined by the strength failure; (c) Failure mode switches from the instability failure to the strength failure when the initial internal pressure or side length increases, and the transition occurs earlier when the wrinkling deformation is considered; (d) Bearing capacity varies non-monotonically with the rise-to-span ratio for wind suction and decreases consistently for wind pressure; and (e) When the rise-to-span ratio increases, the failure mode switches from the strength failure to the instability failure and a later transition is observed in the cushions with the wrinkling deformation.