Experimental Evaluation on Structural Behaviors of ETFE Cushion Structures Subjected to Progressive Loading

As a kind of typical air-inflated membrane structure, ethylene–tetrafluoroethylene (ETFE) cushion has become one of the most essential engineering structures in recent decades, especially in the field of large-span spatial structures. This study experimentally investigates the mechanical properties and structural behaviors of ETFE cushion structures subjected to progressive wind loading. Specifically, two identical ETFE cushion models were fabricated based on a three-dimensional patterning design for assembling the experimental system. Progressive wind loading was efficiently simulated by applying air pressure difference directly on the membrane surface by adjusting the internal pressure of an airtight load simulation chamber that was directly connected to the ETFE cushion. The complete experimental system of each ETFE cushion model was acquired by integrating an automatic pressure control device and a measurement device. The ultimate bearing capacities of the structure models were evaluated separately through destructive tests under the progressive wind pressure and suction loads. The internal pressures, geometric shapes, strain distributions, stress distributions, and failure modes of the two ETFE cushion models were monitored and analyzed. In the wind pressure test, the ETFE cushion model was destroyed owing to the tearing destruction of edges under the ultimate bearing capacity of 20 kPa and the maximum membrane stress of 49.8 MPa. In the wind suction test, the ultimate bearing capacity and maximum stress of the structure model were $-10\mathrm{kPa}$ and 40.6 MPa respectively with the tearing breaks on the central welding seams and edges. These insights and findings inspired by the experimental investigations are significant for the structural analysis, optimal design, and safety evaluation of ETFE cushion structures.