Validierung eines numerischen Simulationskonzepts zur Strukturanalyse windbelasteter Membrantragwerke

The susceptibility of membrane structures to fluctuating wind loads due to their flexibility and small inertial mass may lead to severe dynamic amplification of the structural response. This is even more pronounced in the case of low curvature and small prestress values. Thus, the assessment of the structures' stability and safety necessitates the detailed evaluation of the transient loading and furthermore the interaction between the air flow and the structural motions. The use of conservative assumptions leads usually to oversized, heavy and uneconomical structural designs. Moreover, the identification of aeroelastic effects based on standards is typically not possible since for this the interaction of highly turbulent wind flow and the nonlinear structural dynamics must be considered explicitly. The determination of the wind-induced motions of membrane structures with small-scale wind tunnel tests is in general not possible. Hence, there is no established approach to evaluate all relevant structural and fluid phenomena except the construction of prototype structures in real-scale. Computational fluid-structure interaction could overcome simplifications and limitations of existing approaches. E.g. it is particularly suitable for cases of potential aeroelastic instabilities and if the dynamic properties of the construction are altered significantly by the surrounding air. For these reasons, this paper outlines a virtual design methodology for lightweight structures under the impact of fluctuating wind loads and provides results on a unique validation of the method at real scale tests of a highly flexible 29m umbrella. The comparison of the measured data of the prototype and the numerical results is used for the derivation of relevant modelling aspects as well as an assessment of the quality of the results.