Effect of roof heights on dynamic characteristics of wind pressure on square low-rise buildings

The high suction induced by strong wind on a flat roof can result in severe local damage or even in the overturning of the entire roof. The roof height has a significant effect on characteristics of the high wind suction force. The wind pressure on flat roofs of various heights is investigated in this paper. The extreme wind pressure and its position are firstly studied at different wind incidence angles. Proper orthogonal decomposition (POD) and coherence function analyses are then conducted to analyse dynamic characteristics. The results show that the local extreme pressure increases with an increase in roof height. The fluctuation of the separation bubble also increases, and there exists a mode competition of the first two POD modes. On the contrary, the roof height has fewer effects on conical vortices. In addition, two coherent regions (conical vortices) are observed on the roof. Although these two regions have small correlation coefficients, they have a considerably high coherence function at low frequency. These results are expected to contribute to better understanding of high suction characteristics on flat roofs, and can potentially provide guidance for avoiding roof damage induced by strong wind suction.