大跨度桥梁抖振响应的空间非线性时程分析法

3D Nonlinear Time--domain Buffeting Analysis for Long Span Bridges

通常的桥梁抖振分析借助于频域内的反应谱方法，因而局限于线性范围．近年来大跨度桥梁不断兴建，有必要在其风致抖振响应分析中计入结构几何非线性和有效攻角的影响．文中提出了一个桥梁抖振响应的非线性时程分析法．脉动风诱发的抖振力由计算机模拟为多个互相关的随机过程，自激力则表达为桥面运动和脉冲响应函数的卷积形式．在Ｎｅｗｍａｒｋ－β逐步积分算法中，考虑了结构的大变位以及瞬时有效攻角的变化．应用文中方法计算了两座悬索桥的抖振响应时程，并与风洞试验结果进行了对比．

Classical buffeting analysis for bridges resorts to the response spectrum method in the frequency domain and is limited to the linear scope. With the rapid development of long span bridges in the recent years, it is necessary to involve the structural geometric nonlinearrty and the instantaneous effective attack angle when performing the buffeting analysis. In this paper, a nonlinear time--domain buffeting analysis method is proposed. The turbulence-induced buffeting forces are simulated as multi-correlated random processes and the self-excited forces are expressed in the convolution form of impulse response functions and bridge motion. In the solution of the FEM differential equation, the Newmark-β numerical mothod is adopted. The buffeting response histories of two suspension bridges are calculated by the present method and compared with those obtained from wind tunnel test.