Model Updating of Railway Bridge Using In Situ Dynamic Displacement Measurement under Trainloads
Model Updating of Railway Bridge Using In Situ Dynamic Displacement Measurement under Trainloads
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DOI：
10.1061/(asce)be.1943-5592.0000765
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发表时间：
2015-12-01
影响因子：
3.6
通讯作者：
Feng, Maria Q.
中科院分区：
文献类型：
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作者：
Feng, Dongming;Feng, Maria Q.
为了满足铁路桥梁老化监测的需要，提出了一种基于列车荷载作用下桥梁动态位移历史的时域优化有限元模型修正方法。在一座短跨度板梁铁路桥上进行了现场试验，以测量其对不同速度的货运列车荷载的位移响应，采用作者团队最近开发的低成本遥视传感器。建立了考虑列车-轨道-桥梁动力相互作用的桥梁有限元模型。通过灵敏度分析，研究了列车、轨道和桥梁各子系统参数对桥梁动力响应的内在影响。结果表明，桥梁的位移响应主要对桥梁的刚度敏感，而加速度响应受许多其他参数的影响。这说明桥梁动位移比加速度更适合于铁路桥梁刚度的更新。因此，提出了一种基于列车荷载作用下桥梁位移响应测量的模型修正方法。这种方法被应用于短跨度桥梁，首先识别列车速度，然后通过最小化测量和计算的位移时程之间的误差来识别桥梁的刚度。此外，本文还从测量位移和计算位移两个方面研究了频率特性。分析表明，列车荷载不会激励桥梁的固有振型，因为其频率远低于桥梁的固有频率。因此，基于动态响应测量的基于模态识别的有限元模型修正方法很难使用。这通常是小跨度铁路桥的情况，它们往往具有较高的自振频率。本文提出的周期位移测量和时域有限元模型修正方法可以发展成为小跨度铁路桥梁长期结构健康监测的有效工具。(C)2015年美国土木工程师学会。
To address the need for monitoring aging railway bridges, this paper presents a finite-element (FE) model updating approach using time-domain optimization based on in situ measurement of the bridge's dynamic displacement histories under trainloads. Field tests are performed on a short-span plate girder railway bridge to measure its displacement response to freight trainloads with different speeds using a low-cost remote vision sensor recently developed by the authors' group. A FE model of the bridge is developed considering train-track-bridge dynamic interactions. Sensitivity analysis is carried out to investigate the intrinsic effects of parameters of the train, track, and bridge subsystems on the dynamic response of the bridge. It is found that the bridge displacement response is primarily sensitive to the stiffness of the bridge, whereas the acceleration response is affected by many other parameters. This justifies that the bridge dynamic displacement is more suited than acceleration for updating the railway bridge stiffness. Consequently, a model updating approach is proposed using the measurement of bridge displacement response to trainloads. This approach is applied to the short-span bridge to first identify the train speed, followed by the bridge stiffness by minimizing the error between the measured and computed displacement time histories. Furthermore, this paper investigates the frequency characteristics from both the measured and computed displacements. The analysis shows that the trainload does not excite the bridge's natural modes of vibration because the frequency is much lower than the bridge's natural frequencies. Therefore, it is difficult to use the modal identification-based FE model updating methods based on the dynamic response measurement. This is commonly the case for short-span railway bridges, which tend to have high natural frequencies. The proposed periodic displacement measurement and time-domain FE model updating can be developed into an effective tool for long-term structural health monitoring of short-span railway bridges. (C) 2015 American Society of Civil Engineers.