Steady and unsteady aerodynamic forces on a long-span membrane structure

Abstract

This paper reports the steady and unsteady (motion-induced) aerodynamic forces on long-span roofs based on computational fluid dynamics (CFD) analysis with a large eddy simulation (LES). Three types of roofs, i.e., flat, cylindrical, and suspended roofs, are tested. First, the wind pressures on a rigid flat roof in a smooth uniform flow and a turbulent boundary layer are computed. The computational model and method are verified by comparing the obtained wind pressure distributions on the roofs with previous experimental results. Next, a forced vibration test is performed to understand not only the wind pressures on and the flow around the vibrating roof but also the unsteady aerodynamic forces, which are represented by the aerodynamic stiffness and damping. In the test, the roof is forced to vibrate in the first antisymmetric mode. The effects of vibration frequency on the pressure distribution and unsteady aerodynamic forces are investigated. On the basis of the results, the stability of the roofs is discussed. Furthermore, the dynamic response of a flat roof is analyzed considering the fluid–structure interaction (FSI) to investigate the vibration mechanism of the roof in more detail.