阶梯形平屋顶及其参数对建筑屋面极值风压的影响

针对阶梯形平屋面的设计风压系数在前人研究及风荷载规范中都鲜有提及的现状，设计一系列刚体模型测压风洞实验，考察阶梯形平屋顶中等高度建筑的屋面极值风压特性以及阶梯高度和形状的影响。在验证数据可靠性基础上，重点讨论点极值风压及其最不利位置和风向角并据此确定阶梯形平屋顶风压分区；计算面积平均极值风压并将其与美国规范(ASCE7)进行比较。结果表明，阶梯形平屋顶的高层屋面极值负压最不利值与普通平屋顶并无差别，而低层屋面的极值正压和负压受阶梯参数影响明显。除附属面积较小时的负压超过规范限值外，其他面积平均风压结果与规范吻合较好。这些结果不仅能为阶梯形平屋顶的屋面系统设计提供参考，也为其将来纳入我国规范积累了基本数据。

Effect of setback and its parameters on peak wind pressures on multi-level fiat roofs

A wind tunnel experiment on rigid model wind pressure measurement was carried out on a series of medium-rise building models with multi-level flat roofs,in order to study the peak wind pressure characteristics and the effects of parameters of setbacks.Based on the validated experimental data,local peak pressure coefficients and the corresponding unfavorable positions and wind directions were investigated and zone designations were decided according to such results.Area-averaged peak pressure coefficients were then calculated and compared with those in ASCE7-05.The results show no significant difference between minimum negative peak pressures on simple flat roofs and on multi-level flat roofs,while negative and positive extreme pressures on local areas are highly dependent on step geometry.Comparison with ASCE7-05 indicates that the values of negative pressure on the roof with small tributary areas are smaller than those in related contents of the code,while other values agree closely with the code.These results can not only be served as the reference to the wind-resistant design of roofing systems on multi-level flat roofs but also provide basic data for code modifications.