ETFE薄膜结构积水试验与数值分析

Experimental and Numerical Studies on the Ponding of ETFE Foil Structures

膜结构是一种柔性结构,膜面容易发生雨水积留。针对ETFE(四氟乙烯)薄膜结构,利用ANSYS软件通过迭代计算分析了正方形平面膜面和正方形气枕膜面的积水极限承载力,考察不同跨度及矢跨比时的积水进展情况。计算结果显示,厚度为250μm的单层正方形平面膜面,跨度3m时就会发生积水破坏。对于气枕膜面,是否发生积水破坏由跨度与矢跨比决定。由两层厚度为250μm的ETFE薄膜叠合的正方形边界气枕膜面,当跨度达到5m时将发生积水破坏,跨度为4m、矢跨比达到1/8及以上时也将发生积水破坏。设计制作了3种矢跨比的ETFE薄膜气枕膜面,进行了积水承载试验,将试验结果与数值分析结果进行了对比。

Membrane structure is a kind of flexible structure. The ponding phenomenon of membrane surface is likely to happen in heavy rains, In this paper, the structural behavior of ETFE foil structures under ponding water are numerically analyzed through an iterative method by using the ANSYS software package. Two numerical examples, the plane model and the cushion model, are investigated and the results of parameter studies are given. It is shown that the ponding phenomenon will happen when the span of plane ETFE model exceeds 3 m and the thickness of foil is 250/,m. For the ETFE cushion model, the ponding phenomenon is determined not only by the span of the cushion but also by the ratio of rise to span. When the span of cushion reaches 5 m, or the ratio of rise to span reaches 1/8 and the span is 4 m, ponding phenomenon will happen for the double-layer cushion. In the end, water loading experiments on an ETFE cushion model are carried out and the results from both the numerical analysis and experiments are discussed.