STUDY ON MECHANICAL PROPERTIES OF ETFE CUSHIONS BASED ON INTERACTION MODEL

The enclosed air of an ETFE cushion is assumed to be a potential flow. By introducing the interface coupling conditions and boundary conditions and combining the wave equation of the enclosed air with the dynamic equation of the outer membrane, the finite element interaction equation of an ETFE cushion system is derived. Then a numerical model of an ETFE cushion is established based on the interaction equation, and form-finding analysis and static loading analysis are performed. The comparison of the analytical results with existing test results indicates that the numerical model is valid. In addition, the failure modes and failure criteria of an ETFE cushion are defined based on the bearing capacity analysis. Finally, the influence of sizes, rise span ratios and membrane thicknesses on the relationship between internal pressure and bearing capacity of ETFE cushions are separately studied. It will provide some quantitative guidance for structural designers of ETFE cushions. The results show that the failure of an ETFE cushion under wind loads will occur in two forms: strength failure and stability failure. In the common range of internal pressure, there is an optimum pressure which makes the ETFE cushion reach to its maximum capacity. The changes of size, rise span ratios and membrane thicknesses can have significant effects on the capacity of ETFE cushions.