Turbulent wind forces on a large span roof and their representation by equivalent static loads

Abstract

The paper describes the measurement of the steady and fluctuating wind forces on a large span roof and their representation by equivalent static loads. The work was undertaken as part of a study for the Olympic Saddledome, Calgary, Canada, but has quite general applicability to other large span roofs. The procedure defines the shape of the structural loading in terms of simple patterns; in this case, harmonic Fourier functions were chosen. The force coefficients defining the amplitudes of these orthogonal loading patterns are each summarized by a mean coefficient [Formula: see text]; a root-mean-square fluctuating coefficient, [Formula: see text]; and a resonant magnification factor, (RMF)i. The equivalent static design pressure loading, pD(r,θ), over the roof surface is then represented by an expression[Formula: see text]in which r and θ are polar coordinates, q is the reference velocity pressure of the wind [Formula: see text], gi, is a statistical load combination factor, and μi(r,θ) is the shape of the ith pattern or function.Aerodynamic data defining these coefficients were derived from a boundary layer wind tunnel investigation, using an adaptation of the pneumatic averaging technique. As well as the distributed force coefficients, local pressure coefficients are also given. The dynamic content of the loading was found to be highly significant both on account of its magnitude, which was larger than the mean, and because of its variable distribution. Approximately one-quarter of the dynamic loading might be associated with resonance amplification. Key words: aerodynamics, arenas, design, dynamics, pressure, roofs, turbulent flow, wind loads, wind tunnel tests.