基于力协方差法等效静力风荷载共振耦合效应分析

Analysis on modal coupling effects of resonant components of equivalent static wind loads based on force covariance method

针对等效静力风荷载(ESWL)传统计算方法在处理强耦合结构共振模态之间耦合项的不足,提出基于共振恢复力协方差法能完全考虑各共振模态之间耦合效应的计算方法。具体思路为:从结构运动方程出发,推导出广义共振模态位移响应协方差矩阵;进而基于惯性风荷载法(IWL)获取仅包含共振分量的弹性恢复力协方差矩阵;再采用荷载-响应相关方法(LRC)进行共振响应及其ESWL的计算。该方法避开求解弹性恢复力的积分过程,考虑了各阶共振分量之间的耦合性,且物理意义明确,从理论上适用于任意复杂结构ESWL共振分量计算。以某电厂超大型冷却塔为例,进行结构风致响应和ESWL计算,讨论了共振分量的耦合效应,验证了该方法的有效性。

The traditional calculating methods for equivalent static wind loads have the problems on the coupled effect between resonant modes, the method of considering the resonant responses modal coupling effects was proposed. Firstly, the generalized resonant modal displacement covariance matrix was obtained from structural equation of motion ; then based on IWL method, covariance matrix of elastic restoring force containing the resonant components was obtained; at last the resonant response and equivalent static wind loads were calculated with loads-response correlation method （LRC）. The proposed procedure avoids the integration process of calculating elastic restoring force and completely considers the modal coupling effects, which could be used to calculate the ESWL for any complex structures. The calculation of wind-induced responses and equivalent static wind loads of a power plant super large cooling tower demonstrated the effectiveness of the present approach.