分离双钢箱梁桥的涡振机理及气动减振措施研究

There are more and more long-span bridges with steel box girder built in China.Bridge with steel box girder is prone to vortex-induced vibration due to its light mass and low damping. At present,research on vortex-induced vibration of bridges with steel box girder mainly focus on single steel box girder. Because of aerodynamic interference effect,vortex-induced vibration of bridge with twin separate steel box girder is more complicated. In present proposal, synchronous vibration and pressure-measured wind tunnel test of sectional model and CFD numerical simulation will be performed to study vortex-induced vibration mechanism and aerodynamic vibration restriction measure based on proper orthogonal decomposition technique,block analysis method and dynamic grid technique. By comparing modal characteristic distribution function of surfacepressure,work-doing characteristic of aerodynamic force in different surface region,formation, movement and development of vortex, the vortex-induced vibration mechanism of twin steel box girders will be analyzed from several viewpoints, such as vortex-induced force composition, energy, flow field and so on. On the basis of reveal of mechanism, the availability of some aerodynamic vibration restriction measures,such as airflow-suppressing board, guide vane,segregation board and so on, will be checked. The vibration restriction mechanism of the aerodynamic measures will be analyzed. The research result of present proposal will provide reference and guidance for vortex-induced vibration design and restriction of bridges with twin separate steel box girders.

我国大跨度钢箱梁桥越来越多。钢箱梁桥质量轻、阻尼小，主梁容易发生涡激振动。目前钢箱梁桥的涡振研究主要针对单箱钢梁桥展开，具有完全分离双箱的钢梁桥存在两箱之间的气动干扰作用，涡振问题更为复杂。本项目将结合节段模型同步测振测压试验和CFD数值模拟两种手段，采用特征正交分解技术、分块分析方法和动网格技术，开展分离双钢箱梁桥的涡振机理及气动减振措施研究。通过对比单、双箱梁模型表面压力模态特征函数的分布特征、模型表面不同区域气动力的做功特点、旋涡在模型表面的形成、运动与发展，从涡激力成分、能量与流场等多个角度剖析分离双钢箱梁桥的涡振机理。在揭示涡振机理的基础上，重点研究导流板、抑流板及隔离板等气动措施对分离双钢箱梁桥涡振的减振效果，并探析各种措施的减振机理。本项目研究成果将为分离双钢箱梁桥的涡振抗风设计与减振提供指导和借鉴。

我国大跨度分离双钢箱梁桥越来越多。由于气动干扰作用，此类桥梁的涡振问题非常复杂。为了避免分离双钢箱梁桥发生大幅的涡激振动，十分有必要对其涡振特性、机理及气动减振措施展开深入研究。.本项目结合节段模型风洞试验和CFD数值模拟两种手段，针对两种典型断面钢箱梁—扁平箱梁和钝体箱梁，从多个角度剖析了分离双钢箱梁桥的涡振特性及相关机理。在此基础上，研究了多种气动措施对分离双钢箱梁桥涡振的减振效果。.分离双扁平钢箱梁在较大的正向风攻角条件下容易发生涡振。间距对分离双扁平箱梁涡振的影响可大致分为4个区间。在极小间距条件下，由于“加长体”效应，分离双钢箱梁涡激振动被放大；在较小间距和中等间距条件下，由于“临界间距效应”，分离双钢箱梁涡激振动分别被抑制和放大；在较大间距条件下，由于“尾流紊流效应”，下游箱梁涡激振动被抑制。.在水平来流条件下，分离双钝体钢箱梁涡激振动的气动干扰效应存在比较明显的“临界间距效应”。当间距小于临界间距时，气动干扰对分离双钢箱梁涡振的影响表现为抑制效应，当间距大于临界间距时，气动干扰对分离双钢箱梁涡振的影响表现为放大效应。.在极小间距和较小间距条件下，平板隔流是一种比较有效的分离双钢箱梁桥涡振减振措施。在中等间距和较大间距条件下，导流板和抑流板是比较有效的分离双钢箱梁桥涡振减振措施。.本项目研究成果可为分离双钢箱梁桥的涡振抗风设计与减振提供指导和借鉴。