Computational wind engineering of large umbrella structures

Abstract

The sensitivity of membrane structures to transient wind loads becomes severe at wide spans and low pre-stress levels of the membrane. At stationary wind loads, the elastic behaviour of the flexible membrane leads to deformations with an associated change of the flow conditions and wind pressure distributions. This effect can be enhanced by time dependant fluid fluctuations such as atmospheric or building induced turbulences. Common methods in wind engineering practise like small scale wind tunnel experiments do not fully cover non-linear structural behaviour, contact interaction between membrane and structural elements and the interaction of the flow field with the structural response. Therefore numerical tools are used for the structural design of lightweight membranes. This paper presents results of the first industrial application of the fully coupled fluid structure interaction simulation for aerodynamically sensitive membrane structures situated in a built environment. The dynamic behaviour for gust induced wind loads has been investigated and reaction forces were determined. The application of the fully computational wind engineering method, in time domain, allowing as well for non-linear structural effects as for fluid structure interaction effects, makes the discovery of large dynamic amplification factors possible. The described procedure and results were reviewed and approved by Buro Happold, one of the world leading structural engineering offices.