Fluctuating Wind Pressures on Low Building Roofs

Quasi-steady theory can be used for the prediction of fluctuating wind pressure coefficients acting on the edge strip of flat or low-sloped roofs and the ridge strip of steeper roofs of low buildings. Comparisons with experimental data indicate that the quasi-steady model, expressing the root mean square pressure coefficients as functions of mean pressure coefficients and the turbulence intensity at eave height, predicts the fluctuating wind pressures for wind directions normal to the roof edge; for oblique wind directions the model holds for flat or low-sloped roofs but only for the edge strip away from the corners. Many older test results dealing only with mean pressures may now be used with the model suggested to yield root mean square pressure coefficients. The latter can lead to the prediction of expected peak pressures, which are necessary for design, if an appropriate load probability distribution is assumed.