Wind-induced dynamic response and resultant load estimation for a flat long-span roof

The design wind load for a flat roof structure has been investigated based on a statistical analysis of the dynamic response to turbulent wind forces. The subject of this study is a flat long-span roof which covers a low-rise square building with a span/height ratio of 3 to 6. The roof structure is supposed to act like an elastic plate under wind loadings and the modal force of the first vibration mode is measured for various wind directions in two turbulent boundary layers with different mean velocity and turbulence intensity profiles. A pneumatic averaging technique is applied to measure the modal force directly in the wind-tunnel experiments. On the basis of the results, the gust loading factor, defined as the ratio of the maximum peak response to the mean response in a time duration, was computed. The effects of the flow characteristics and of the geometric and structural properties of the roof on the gust loading factor are discussed.