Roof slope effects on the correlations of wind pressures on low-rise building roofs

The roof configuration of a building is crucial in determining the flow patterns around structures, thereby affecting the aerodynamic loads on these structures. This study investigates the effects of roof slope on wind pressure correlations over roof surfaces using boundary-layer wind tunnel data from Tokyo Polytechnic University (TPU), Japan. Thirty-two building models, with a plan aspect ratio of 2:3, varying heights, and roof slopes ranging from 4.8° to 45° under suburban terrain, are analyzed in this study. The distribution of mean wind pressure coefficients is examined to characterize flow patterns over roofs, and wind pressure correlations are evaluated with the underlying mechanisms discussed. The results demonstrate that buildings with roof slopes below 9o exhibit similar flow patterns in terms of mean wind pressure coefficient distribution. For roof slopes between 9° and 18°, wind flow re-separates at the ridge and may reattach on the leeward roof. For roof slopes exceeding 18°, no reattachment is observed on the leeward roof. At roof slopes greater than 25°, positive pressures are observed across the windward roof. Within the separation bubble, the mean reattachment length (Xr) is a key parameter for characterizing the distribution of correlation coefficients of wind pressures. In addition, for wind perpendicular to the ridge, high correlation coefficients on both windward and leeward roofs are observed for steep roofs. On the leeward side, correlations approach 0.7 for roof slopes exceeding 27°. Under cornering winds at 45°, correlations in the windward corner regions increase with roof slope, reaching values above 0.9 for a 45° roof.