大跨屋盖结构等效静风荷载研究

等效静风荷载为大跨屋盖结构设计提供了处理时空变化动力风荷载的有效途径。从两个方案对等效静风荷载研究,一种方案是采用模态等效静风荷载组合法,另一方案采用共振响应分量对应的模态等效静风荷载与本征正交分解法(POD)简化的荷载响应相关法(LRC)计算的背景等效静风荷载组合法,两个方案中通过加权因子考虑模态耦合项的影响。利用风洞试验同步测量单层柱面网壳结构的风压数据,根据完全二次型组合法(CQC)和平方总和开方法(SRSS)计算风致响应,结果表明模态耦合项可以忽略,仅选取前几阶模态即可获得准确响应结果。等效静风荷载计算的响应结果与CQC法计算结果进行校核。等效静风荷载确定两方案对比分析显示,第一种方案是非常有效、实用的确定等效静风荷载的方法,而第二个方案有助于分别对背景和共振等效静风荷载研究。

EQUIVALENT STATIC WIND LOADS ON LONG SPAN ROOFS

The equivalent static wind loads (ESWL) provide an effective approach to deal with the spatiotemporally varying wind loads for structures with long span roofs. Two schemes for calculating the ESWL have been proposed in this paper. In the first scheme ESWL are formulated in terms of a weighted combination of modal ESWL components. In the second scheme ESWL are expressed in a separated form as the resonant component of modal ESWL and the background component in which the proper orthogonal decomposition (POD) technique can be introduced to simplify the computation of load-response-correlation. The modal coupling effects are considered with the weighting factor in both schemes. Wind tunnel tests of a single-layer latticed cylinder were carried out with the synchronous multi-pressure scanning technique. With the wind-induced responses of the cylinder calculated using approaches of the Complete Quadratic Combination (CQC) and the Square Root Sum of Square (SRSS), it is found that the modal coupling effects may be neglected in this case, and the responses can be obtained with only a few modes. The obtained responses by ESWL are checked by CQC. By comparing the two schemes for calculating ESWL, it can be concluded that the first scheme is an effective and practical method for analysis of the equivalent static wind loads, and the second scheme is useful to investigate background and resonant static loads component respectively.