基于频率法的质量块影响索力敏感性分析

Sensitivity analysis of mass influence on cable force based on frequency method

以实体工程中的某矮塔斜拉桥为项目依托,针对C1X索力张拉后实测索力偏小的情况,运用有限元软件建立模型,结合频率法测索力方法理论,从PE护套在索长方向质量密度不均匀分布及斜拉索附加集中质量块两方面进行影响索力因素的敏感性分析,得出斜拉索中间段附加质量块及线密度不均匀分布对索力均有影响。在锚固端附近斜拉索质量密度的改变对索力敏感性影响较小;斜拉索跨中区域附近斜拉索质量密度的改变对索力敏感性较大,导致实测频率明显减小,使得按理论计算出索力偏小;较长的斜拉索附加质量块和线密度对索力敏感性更高。建议在实际索力测试中要重视现场附加质量块和线密度分布不均的影响,根据现场情况及时修正频率法测试索力公式中的参数,控制好索力张拉工作,保证桥梁受力状态良好。

Based on the real engineering project of low-pylon cable stayed bridge,in view of the fact that the cable tension of C1 X is smaller than the design,the finite element software was used to establish the model while combining the frequency method measure theory,making sensitivity analysis of the influence factors of cable forces from two aspects which are the inhomogeneous mass density of PE sheath along the cable length and the additional mass concentration in the cable.It is concluded that the additional mass and the inhomogeneous linear density of the middle section of the cable have great influence on the cable force.The differences of the mass density in the cable near the anchorage end has a little effect on the cable force sensitivity while it does obvious effect when the additional mass near the middle of cable,which makes the measured frequency smaller the real cable force smaller and the additional mass and linear density are more sensitive to the long cable' force.It is needed to pay more attention in the actual cable force test based on frequency method,to modify frequency method formula parameters when measuring cable force and ensure that the bridge is in good condition.