Wind gust pressures on buildings

Design wind loads for building structures are usually based on the simplified concept of a steady wind, and the model tests used to determine design pressure coefficients are made in low-turbulence, constant velocity wind tunnels.A statistical approach is required for a more realistic analysis of the loads caused by the gusty wind actually encountered in Nature. Model tests should be made in a boundary layer type wind tunnel in which the rate of increase of velocity with height above ground and the turbulence level (ratio of standard deviation to mean velocity) of real wind are properly simulated.Full-scale measurements have been made on a 34-storey building in the centre of a large city to assist in the development and verification of modelling techniques to be used for simulating real wind conditions.Full-scale results and measurements in a boundary layer wind tunnel are compared. Empirical expressions for the statistical properties of strong winds are examined. Size reduction factors and gust factors are discussed with reference to the measurements obtained and the static-dynamic design approach suggested by Davenport.