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钢混组合梁桥顶推施工应力实时监测及数据分析

Real-time Stress Monitoring and Data Analysis during Incremental Launching Construction of Steel-concrete Composite Beam Bridges

  • 摘要: 本研究以开达路跨广深高速钢混组合连续梁桥(主跨65 m)顶推工程为背景,旨在精准掌握钢混组合梁桥顶推施工过程中的力学性能与结构安全性,进而保障施工精度。首先,基于Midas/Civil有限元软件建立了考虑临时支撑脱空(采用只受压弹性支承模拟)及已浇筑桥面板等效荷载的全桥二维和三维模型,按施工方案划分8个工况进行仿真分析,识别出顶推过程中最大正、负弯矩关键截面位置。随后,针对识别出的关键截面,制定了详细的应力实时监测方案:每个截面布置6个振弦式应变计测点,采用Datataker DT85G数据采集仪,结合无线网桥传输技术与移动电源独立供电系统,制定了高稳定性、低延迟(<200 ms)的远程实时监测方案。监测数据分析表明:钢箱梁整体性良好,受力均匀,无局部屈曲现象;截面变形符合平截面假定,结构处于线弹性状态。研究同时发现,日照引起的显著非均匀温度梯度(如监测时段上部测点应变峰值40.2 µƐ较下部高39.5%,左侧应变幅值较右侧高9.8%)导致结构产生应力重分布,并可能产生附加弯矩与扭矩,致使梁体线形偏离设计位置。为提高顶推施工精度,建议进行多源监测与数值模拟协同管控。

     

    Abstract: This study is based on the jack-pushing project of the steel-concrete composite continuous beam bridge (main span of 65 meters) over the Kaida Road crossing the Guangzhou-Shenzhen Expressway. It aims to accurately grasp the mechanical properties and structural safety of the steel-concrete composite beam bridge during the jack-pushing construction process, thereby ensuring construction accuracy. Firstly, based on the Midas/Civil finite element software, a two-dimensional and three-dimensional model of the entire bridge considering the voids in temporary supports (simulated using only compression-only elastic supports) and equivalent loads of the poured bridge deck was established. Eight working conditions were divided according to the construction plan for simulation analysis, and the key section positions of maximum positive and negative bending moments during the jack-pushing process were identified. Subsequently, for the identified key sections, a detailed real-time stress monitoring plan was formulated: six vibrating wire strain gauge measuring points were arranged on each section, and a Datataker DT85G data acquisition instrument was used, combined with wireless bridge transmission technology and a mobile power supply independent power supply system, to develop a high-stability, low-latency (<200 ms) remote real-time monitoring plan. The monitoring data analysis showed that the steel box girder had good integrity, uniform stress distribution, and no local buckling phenomenon; the section deformation conformed to the plane section assumption, and the structure was in a linear elastic state. The study also found that significant non-uniform temperature gradients caused by sunlight (such as the strain peak value of 40.2 µε at the upper measuring point being 39.5% higher than that at the lower measuring point, and the strain amplitude at the left side being 9.8% higher than that at the right side during the monitoring period) led to stress redistribution in the structure and may generate additional bending moments and torques, causing the beam alignment to deviate from the design position. To improve the accuracy of the jack-pushing construction, it is recommended to carry out multi-source monitoring and numerical simulation collaborative control.

     

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