应用拉索频率方程修正数值解的索力识别方法

Cable Force Identification Based on Corrected Numerical Resolution of Cable Frequency Functions

精确测量拉索索力是进行斜拉桥健康监测和工作状态评估的关键。在不考虑垂度、刚度、边界条件等因素的影响的条件下应用振动频率显式公式法识别实际工程中的拉索索力,会造成相当程度的误差。首先,通过对考虑上述条件时的隐式拉索频率方程零根的数值求解,给出了索力和频率的间接计算方法;其次,通过数值仿真,研究了该方法对索振动频率和索力识别误差的规律;最后,在此基础上建立了进一步的经验误差修正公式。实例研究表明,与其他显式公式方法相比,基于频率方程数值解的方法显著提高了识别精度,在此基础上进行的经验误差修正,可进一步大幅提高索力索频的识别精度;与有限元模型修正法相比,建议的方法计算耗时更小。

Accurate cable tension identification is the key to health monitoring and condition assessment of cable stayed bridge.Error must not be overlooked when applying vibration based formulas to identify the tension of real cables under sag,stiffness and boundary conditions.By numerically resolving the implicit frequency function of real cables with the above conditions,the indirect cable force identification method and corresponding cable mode frequency calculation method are investigated.The error of tension is studied using numerical simulation,and an empirical error correction formula is presented to fit the relationship between cable force error and cable parametersξandλ2.A case study on two real cables form the Shanghai Changjiang bridge shows that the method discussed in this paper can increase the accuracy of the cable force and reduce computing CPU time compared with FEM.