拱肋分幅转体施工过程抗风性能研究

Research on Wind Resistance During Split Rotation Construction of Arch Rib

拱肋分幅转体能有效解决整体转体时转盘过大、开挖方量大的问题,相较于双拱肋整体转体,其转动体系相对较柔,施工过程中体系的抗风性能需重点关注。为合理评估施工过程中的风致振动效应,对比介绍了基于时间历程的动力分析方法和基于规范层面的等效静态分析方法的计算过程及其软件实现细节,讨论了2种方法计算结果的差异性和规律性。结果表明:该转体桥例尽管静力荷载数值总体上要大于动力的情况,但静力分析方法仍低估了风致作用下拱肋的位移响应,且体系越柔,这种低估程度越明显,某些情况达30%。另外,还针对不同动力特性转体施工体系振动控制措施的有效性进行了系统评估,案例的抗风缆索对转体过程中风致拱肋的振动控制效果较差,即使对于很柔的体系,减振系数也不超过7%。

Split rotation construction of arch rib can effectively solve the problem that the rotary plate is too large and the excavation square is too large during the overall rotation,Compared with the double arch rib overall rotation,its rotation system is relatively soft,and the wind resistance performance of the system needs to be paid attention to during the construction process.In order to evaluate the wind⁃induced vibration effect in the construction process,the calculation process and software implementation details of the dynamic analysis method based on time history and the equivalent static analysis method based on the specification level are introduced and compared,then the difference and regularity of the calculation results of the two methods are discussed.The results show that for the example of rotary bridge,the static analysis method still underestimates the displacement response of arch ribs under wind action,although the static load value is generally greater than the dynamic load value.The more flexible the system is,the more obvious the underestimation is,up to 30%in some cases.In addition,the effectiveness of vibration control measures for rotary construction systems with different dynamic characteristics is also evaluated.The vibration control effect of windproof cable on the wind⁃induced arch rib in the process of rotary is poor,even for the very soft system,the vibration absorber coefficient is not more than 7%.