Disturbed uneven roof snow loads in built-up environments: Influence of adjacent buildings with diverse roof shapes

With the intensification of global climate change, extreme snow disasters are occurring with increasing frequency. In built-up environments, snow accumulation on certain roofs can increase abruptly under the shelters of adjacent buildings. This interference-induced snow load amplification will impose a heavy burden on roof structures, threatening their safety. Among these structures, lightweight gable or arched roofs are particularly vulnerable, as their geometry promotes the development of uneven snowdrifts. Although current load codes have incorporated exposure coefficients to account for the interference effects, these coefficients fail to consider the influence of roof shapes due to the lack of data. Therefore, this study delves into the snowdrift characteristics under the interference of tandem-arranged buildings with various roof shapes. Firstly, systematical wind tunnel tests were conducted to explore the snowdrifts on two tandem-arranged roofs with three typical snow-sensitive roof shapes. Based on the wind tunnel test data of snowdrifts and numerical simulation results of the flow field around the buildings, the interference mechanisms of snow loads on different roofs were thoroughly analyzed. Overall, the snow load on the downstream disturbed roof basically stays unchangeable with various upstream interfering roof shapes, but exhibits strong sensitivity to the roof shape of the downstream disturbed building itself. For different disturbed buildings, the gable roofs are most sensitive to the interference from upstream buildings, while the flat roofs demonstrate strong anti-interference capability. To fully consider the increased snow loads caused by interference effects, it is recommended to adjust the exposure coefficients according to the specific roof shape and reasonably increase the exposure coefficients for double-pitched roofs.