基于试验模态参数的索-拱铁路桥的改进有限元模型

介绍基于模态参数的索-拱铁路桥的校准数值模型。基于扩大的频域分解法,采用只输出技术,通过扰动测试来确定自振频率,桥梁振动的整体和局部模态对应的振型及阻尼系数。采用一种遗传算法对数值模型进行改进,该算法可以在数值模型的15个参数中得到最优解。为了与模态匹配,采用了一种基于模态应变能计算的新技术。考虑到不同的初始种群,大量参数的稳定性证明了数值模型在优化范围内所采用优化算法的鲁棒性。通过一个混凝土的变形模量的特征试验和铁路运输下的动力试验,对改进的数值模型进行了验证。结果显示数值模拟结果与试验结果吻合较好。

Finite Element Model Updating of a Bowstring- Arch Railway Bridge Based on Experimental Modal Parameters

This article describes the calibration of the numerical model of a bowstring-arch railway bridge based on modal parameters.An ambient vibration test allowed the identification of the natural frequencies,mode shapes and damping coefficients of several global and local modes of vibration of the bridge by the application of an output-only technique based on the enhanced frequency domain decomposition method.The calibration was performed using agenetic algorithm that allowed obtaining the optimal values of fifteen parameters of the numerical model.For the mode pairing,a new technique based on the calculation of the modal strain energy was used.The stability of a significant number of parameters,considering different initial populations,proved the robustness of the adopted algorithm in the scope of the optimization of the numerical model.The updated numerical model was validated based on an experimental test for the characterization of the modulus of deformability of the concrete and a dynamic test under railway traffic.The results showed an excellent agreement between numerical and experimental results.