Horizontal Wind Loads on Open-Frame, Low-Rise Buildings

Wind tunnel tests of open-frame, low-rise buildings were carried out to determine the drag (base shear) and bracing loads in the direction normal to the frames (parallel to the ridge). In total, 18 configurations were examined in an open country terrain at a scale of 1:100. The worst wind angles for all configurations are between 0°–40° with 20°–30° typically yielding slightly higher loads, 0° being parallel to the ridge. The largest load coefficients are observed for the smallest frame buildings, consistent with observations for enclosed buildings, which is due to three-dimensional (edge) effects. The solidity ratio has a clear effect on the load coefficients with higher coefficients for lower solidity, similar to the behavior observed on lattice frames or trussed towers. However, when these coefficients are multiplied by the solidity ratio, so that they can be directly compared to enclosed building coefficients, it is clear that the total load increases monotonically with solid area. Bracing was observed to take up to 75% of the total drag load. An empirical model was developed for obtaining design loads.