桥梁移动荷载识别的不适定性及其试验研究

对桥梁移动荷载识别方程不适定问题进行研究，提出采用预处理共轭梯度法（PCGM）求解超定方程组，通过选择不同的预优矩阵，改善和解决超定方程组的欠秩和病态问题。为验证基于PCGM方法的现场实用性，设计制作了车桥试验模型，通过试验采集到的桥梁弯矩响应数据识别桥面移动荷载。比较桥梁模态数、预处理共轭梯度法迭代次数、桥面粗糙度、车辆重量以及测点选择对识别结果精度的影响后，研究结果表明：基于PCGM方法能够很好地识别车辆荷载，收敛较快且能较好改善荷载识别方程的不适定性。

Experimental Study on ILL-conditioning Problem in Identification of Moving Vehicle Loads on Bridge

The ill-conditioning problems in identification of moving vehicle loads on bridge are investigated. The moving dynamic vehicle loads are identified from the measured bending moment responses of a bridge model fabricated in the laboratory. The preconditioned conjugate gradient method (PCGM) is adopted to solve the system equation on moving force identification problem. The solution of the ill-posed problem existing in the inverse process of moving force identification is improved by proper selection of preconditioned matrix in the PCGM. Some influential parameters are examined by comparing the identified results under some different experimental cases. The assessment results show that the identified results based on PCGM are provided with higher identification accuracy, fast convergence and robust immunity to the ill-conditioning problem of moving force identification.