连续梁桥水平转体过程中振动加速度与整体稳定性的关系研究

Research of Relationship Between Vibration Acceleration and Stability of Continuous Beam Bridge During Flat Rotation

为保证桥梁在水平转体施工过程中的安全,提出一种基于振动加速度监测的转体结构整体稳定性监控方法。首先,通过对比一座高铁特大桥转体过程实测振动数据与有限元模态分析结果,可知转体结构纵桥向立面内的振动主要受面内前3阶振型控制,而与整体稳定性相关的墩底弯矩仅受其中两阶非对称振型影响。然后,推导出转体结构以纵桥向立面内单个非对称振型振动时振动加速度与墩底弯矩比值的解析公式,并通过有限元模拟加以验证,表明将主梁简化为无限自由度等直杆、将桥墩简化为集中质量梁单元的解析公式能够在工程允许的误差范围内描述转体结构以指定振型振动时振动加速度与墩底弯矩的关系。最后,将转体结构的振动简化为纵桥向立面内前2阶非对称振型振动的叠加,给出高铁常见转体结构墩顶顺桥向振动加速度限值的推荐计算公式及相应计算结果,可为同类工程提供参考。

In order to guarantee the construction safety during the flat rotation process of rotary structures,a method was proposed to monitor the stability of the structures in real time by measuring the vibration accelera-tion of the rotary structure.First,the vibration data,collected during flat rotation of a high-speed railway bridge structure,were compared with the result of finite element modality analysis.The result showed that the vibration in elevation of rotary structure was mainly influenced by the first three order vibration modes in eleva-tion,and the pier bending moment related to stability was only affected by the two asymmetrical vibration modes.Then,the analytic formula of the ratio of vibration acceleration and pier bending moment for the rotary structure was deduced under the condition when the rotary structure was vibrating in single asymmetrical vibra-tion mode.Verified by finite element modeling,the analytic formula,considering cantilever beam as infinite degree of freedom straight rod and pier as the lumped mass matrix beam element,can describe the relationship between vibration acceleration and pier bending moment within the range of the engineering allowable error when the rotary structure was vibrating under specified vibration mode.Finally,the vibration of rotary struc-ture was simplified as the superposition of the first two asymmetrical vibration modes in elevation of rotary structure.The recommended formula of permissible value of vibration acceleration for passenger dedicated line bridges is given,to provide a reference for similar proj ects.