【摘要】 将桥梁结构与气流作为一个系统 ,从能量平衡的角度研究系统的颤振稳定性。首先建立了系统能量变化率与系统等效阻尼比之间的关系 ,由不同风速下系统的等效阻尼比判断系统的颤振稳定性 ,推演了系统及各阶模态等效阻尼比的计算方法。以英国塞文桥为算例 ,验证了本方法的可靠性 ,并用于对系统发生颤振时多模态间的耦合机理进行研究。为了进一步探明多模态耦合对不同体系悬索桥颤振稳定性的影响 ,以我国虎门悬索桥和一座跨海桥设计方案为工程背景 ,证实了由扁平钢箱梁作为主梁的悬索桥 ,若结构对称其颤振形态将为对称模式 ,且系统颤振主要受第一阶对称扭转模态及低阶对称竖弯模态控制 ,高阶模态的影响很小 ;并发现了一个新的现象 :对于单跨悬索桥 ,多模态分析所得临界风速一般低于二模态分析结果 ,而对于三跨悬索桥(包括三跨两铰和三跨连续 )趋势正好相反 ,这一发现对于工程实践将具有重要意义。更多还原

【Abstract】 A flutter stability of the suspension bridge is studied from the standpoint of energy balance. The relation between the change ratio of a system energy and the equivalent damping ratio of the system is built. A method to calculating the equivalent damping ratio of each mode and system is proposed in the paper. The flutter stability of a system is depended on the equivalent damping ratio of different wind speed. The reliability of the method is illustrated by the British Severn bridge. The mechanism of multi?mode coupling when a system induced flutter is also examined in the paper. To illustrate the influence of multi?mode coupling on different structural systems of suspension bridges, the Humen bridge and the designed project of a sea?crossing bridge are taken as an example. Some useful conclusion is obtained through the study.更多还原