Effective Wind Loads on Flat Roofs

An experimental investigation of wind-induced pressure loads acting on two square-plan flat-roofed model structures (50ft and 225ft high in full scale) is described. Measurements of mean, peak, and root mean square pressures acting on points and over larger roof areas have been made in turbulent boundary layer flow simulating wind over urban and open country terrains. Area loads on the roofs have been measured both by a pneumatic-averaging technique, and by using a large flush-diaphragm transducer. Correlation coefficients and spectra of effective pressure loads on various regions of the roofs are also presented. A significant overestimation of peak loads may occur for larger areas if full correlation of the worst point pressures acting over the area is assumed.