基于时频混合格式的桥梁抖振响应计算方法

Calculation method of bridge buffeting responses using an alternating frequency-time domain method

利用一种时频混合格式计算桥梁在紊流风激励下的抖振时程响应。针对动力风荷载既有时域内定义的抖振激励力,又有用频域内的颤振导数来定义的与结构自身运动有关的气弹自激力,存在时频混合项的特点,引入时频混合格式的AFT方法来计算桥梁抖振时程响应;在保持频域计算高效性的同时,又通过拟力概念在时域计算结构非线性不平衡力和气弹力造成的振型耦合,通过迭代使其收敛。通过算例验证了该格式是一种可行的计算桥梁抖振响应的方法。

Authors describe an analysis of bridge buffeting response by using an alternating frequency-time domain (AFT) method. Since the wind loads include both the buffeting loads and the self-excited (motion-induced) loads of which the latter part is commonly defined by frequency domain flutter derivatives, the AFT method is introduced to employ the advantages of both domains by performing convolutions in the frequency domain and switching to the time-history to evaluate the nonlinear forces as functions of the state trajectory and structural coupling between different modes; moreover, taking advantage of the pseudo-force concept, coupled self-excited terms are easily incorporated in time-history. The AFT algorithm makes this approach computationally advantageous. Through an example bridge, the validity and efficiency of the presented method are confirmed.