Wind Pressure Functions for Flat Roofs

Weighted Legendre polynomials are shown to represent adequately the distribution of mean and root mean square (rms) wind pressure coefficients on rectangular flat roofs for wind normal to the building faces. Peak pressure coefficients cannot be fitted by the same analytical model, but their variation can be represented from the mean and rms pressure distribution and the assumption of an appropriate probability density function. A quasi-steady theory is suggested for the prediction of rms pressure coefficients from measurements of mean pressure coefficients acting on roof edges. Experimental data obtained from models in turbulent boundary layer flow simulating wind over open country and urban terrains show good agreement with the analytical models.