桥梁移动荷载识别及其PCGM预优矩阵选取

基于时域法(TDM)求解思路,结合桥梁移动荷载特点,采用预处理共轭梯度法(PCGM)由梁的弯矩响应、加速度响应及其响应组合来识别桥梁移动荷载,重点比较在方程组不适定以及测量响应受噪声影响情况下不同预优矩阵对识别精度的影响,从而得到可用于移动荷载识别的最优预优矩阵.仿真结果表明,在绝大多数工况下,预处理共轭梯度法均能精确识别桥梁移动荷载,但不同预优矩阵对测量噪声及识别方程的不适定性有不同的抵抗能力,且对预处理共轭梯度法的收敛速度、识别精度也存在不同影响；合理选取预优矩阵能够有效提高桥梁移动荷载识别预处理共轭梯度法的精度和效率.

Effect of preconditioned matrix on PCGM used for identification of dynamic axle loads on bridge

According to characteristics of moving dynamic loads on bridges and tracking the time domain method (TDM), the moving dynamic axle loads were identified from bridge bending responses, acceleration responses or their combination based on a preconditioned conjugate gradient method (PCGM). It aimed at obtaining the most accurate preconditioned matrix by comparing effect of preconditioned matrixes on identification accuracy. Simulation results showed that the PCGM could accurately identify the dynamic axle loads on bridges in most cases. However, there was different identification accuracy and immunity to measured noise and to the ill-posed problems of the system equation if different preconditioned matrixes were used. Meanwhile, choosing proper preconditioned matrix could effectively improve both of identification accuracy and efficiency of the PCGM.
Key words:  preconditioned matrix|moving force