基于模态综合理论的斜拉桥时域抖振分析方法

基于大跨度斜拉桥风致抖振时域分析的复杂性，为提高时域分析效率，引入模态综合理论，提出一种斜拉桥抖振时域分析方法，并通过算例自编程序验证其正确性与可行性。考虑自然风的相关特性，采用谱解法将三维随机风场简化，横桥向和顺桥向风速谱采用沿高度变化的Simiu谱，竖向风速谱采用Lumley—Panofsky谱，编制程序实现大跨度斜拉桥随机风场的数值模拟，得到施加于结构上的风荷载时程。研究表明，大型结构的动力响应主要受若干低阶振型控制，因此在斜拉桥时域分析过程中引入模态综合理论，实现了抖振力和自激力的时域化过程，并且全面地考虑了气动阻尼、气动刚度和气动耦合作用的影响，有效地解决了考虑自激力的时域化过程复杂、计算代价过大的问题；最后通过编制程序对一座大跨度斜拉桥进行不同风速下的抖振时域分析，验证了其实用性。

Analysis Method of Buffeting in Time Domain for Cable-stayed Bridge Based on Modal Integration Theory

Based on the complexity of wind-induced buffeting analysis for long-span cable-stayed bridge, a new time domain buffeting analysis method was put forward by introducing modal integration theory, and experimental computation was carried out to indicate validity and feasibility of the method. Considering the correlation of natural wind, wind velocity field for long- span cable- stayed bridge was simplified and simulated by the spectral representation method. Simiu spectrum was used in transverse and longitudinal direction, while Lumley-Panofsky spectra was used in vertical direction. Then wind load time-history is obtained by program. The previous research demonstrates that the dynamic response of structure is mainly controlled by the lower vibration modes. Therefore, modal integration theory was introduced to realize the time domain process of self-excited force and buffeting force. This method considers the influence of aerodynamic stiffness, aerodynamic damping and aerodynamic coupling comprehensively, which effectively resolves the problems of complex time domain process of considering self-excited force and excessive cost of computation. At last, a time domain buffeting analysis of a long-span cable-stayed bridge under different wind velocities was done to validate the practicability of this buffeting analysis method.