Study Of Wind Loads On Cantilevered Grandstand Roofs

Cantilevered grandstand roofs of large stadiums are generally flexible structures with long-span and lightweight materials and are a kind of typical wind-sensitive structures. Wind-induced loads and vibrations of the cantilevered roofs are usually the major factors which control the security of the structure, especially for large stadiums constructed in the strong wind areas. The main objective of this dissertation is to study the wind load distribution and wind-induced vibration characteristics of the cantilevered grandstand roofs and to gain the results that can oe applied to wind-resistant design of the roofs.The research advances in the area of wind-resistance study on cantilevered grandstand roofs of stadiums are first systematically reviewed in the dissertation. Then the fundamental theory and the governing equations for the numerical simulation of wind pressures on the surface of buildings are established. The numerical simulation method that is based on the average Navier-Stokes equation and the k-e two-equation turbulence model is adopted in the dissertation. Using the method the wind pressures on the surface of a stadium grandstand roof located in Hong Kong are computed and analyzed. The computed results are compared with the corresponding wind tunnel test results and good agreement is found. This demonstrates the validity and accuracy of the numerical method. Then the wind pressures on a cantilevered grandstand roof located in coastal area of Zhejiang Province are determined. Through analysis and comparison of the obtained wind-pressure distribution and their magnitudes, a simplified wind-pressure distribution curve with a rectangle plus a trapezoid is proposed and is compared with the method proposed in the Australian code. The current simplified method is applicable to the wind-resistant design of the same type of roof structures.In order to study the fluctuation characteristics of the wind loads acting on the cantilevered grandstand roofs, the wind-velocity time series of the single point and some correlating points are numerically determined by the AR method. The wind dynamic responses of the cantilevered grandstand roof are computed and discussed by the time-domain analysis method. The obtained results indicate that the half-constant method can be used in the computation of wind-induced vibration of singly standing cantilevered grandstand roofs. Only the background response components for the singly standing roof need to be considered.