Characterisation of pressure fluctuations on the leeward and side faces of rectangular buildings and accuracy of the quasi-steady loads

Equivalent static loads on buildings are usually evaluated following the quasi-steady approach, assuming that instantaneous approaching wind velocities are directly translated into surface pressures at all points on the building faces. Such an approach is in contrast with the actual nature of pressures, acting on the faces, exposed to a separated flow. For these, mean and fluctuating pressures are not directly related to the characteristics of the oncoming flow and, to an even lesser extent are fully correlated to those acting at corresponding points on the windward surfaces. To investigate the characteristics of the pressure fluctuations on the leeward and side faces of medium-rise, rectangular plan buildings and to quantify the error associated with the quasi-steady assumption, in this paper the results of wind tunnel pressure measurements are discussed. The characteristics of fluctuating pressures and the equivalent static load are compared with those arising from the application of the quasi-steady approach and from the use of codes of practice.