考虑空间三维模态及振型修正的高耸结构风振响应分析

Wind-induced vibration response analysis of high-rise lattice structure by considering modification effect for three-dimensional spatial and nonlinear vibration mode shape

采用某假想格构式高耸结构电视塔的高频天平测力风洞试验结果,在对其进行半刚性处理的基础上,用六种不同的方法分别考虑空间三维模态、非直线振型及各方向气动载荷耦合等因素,并考虑单方向一维直线振型的风致位移响应计算结果,在五个不同风向角下进行了电视塔顶部位移均方根响应的对比分析,对比结果表明五个风向角工况下得到的结论基本一致,对比本文算例考虑空间三维模态、非直线振型及各方向气动载荷耦合等因素,进行修正计算的结果在x和y方向减少近21%～37%。相比而言仅考虑振型修正的结果,比仅考虑三维空间振型耦合或基底气动载荷的相关性所产生的差异要大。

Based on the high frequency force balance （HFFB） wind tunnel test results of an idealized high-rise lattice TV tower, the measured base moments were first modified by considering the inherent semi-rigid HFFB scaled model in the wind tunnel test. The modification effect of coupled three-dimension and nonlinear modal shapes and aerodynamic wind loading coupling to the wind-induced response of the high-rise TV tower was investigated by the proposed six different alternative methods respectively. Under the load cases of five wind azimuths, the wind-induced displacements in along-wind and across-wind direction by considering the modal shape and aerodynamic wind loading coupling modification effect were then compared with those corresponding results evaluated by the assumption of idealized one-dimension straight line modal shape in each direction along the major axes of the investigated high-rise structure. The comparison results showed that almost same conclusions can be obtained for the wind-induced responses in the five wind azimuths loading conditions. Compared with wind-induced displacement from the ordinary methods with one-dimension straight line modal shape assumption, the RMS values of wind-induced displacements atop of the structure could be reduced by about 21%-37% when the modification effect of coupled three-dimension and nonlinear modal shapes was considered.The modification effect due to the nonlinear mode shape is relatively more significant than those modification effects due to the influence of three dimensional coupled modal shape or due to the correlation between aerodynamic wind loading at the basement