Dynamic testing methods have been widely used in engineering practice for investigating dynamic properties of bridges; however, only basic dynamic parameters (i.e., natural frequencies, damping ratios, and unscaled modal shapes) can be identified, which are insufficient for condition assessment and health monitoring. To address this limitation, this article takes a three‐span posttensioned concrete bridge as testbed; more useful structural parameters including mass‐normalized mode shapes and scaled flexibility matrix are intended to be identified from moving vehicle‐induced responses. For identifying scaled flexibility matrix, structural scaling factor between arbitrarily scaled mode shapes and mass‐normalized mode shapes needs to be calculated firstly. In this article, time‐varying frequencies of vehicle–bridge interaction (VBI) system were adopted for structural scaling factor identification, and the sensitivity of parameters identification error on calculated scaling factor was also investigated. The effectiveness of the proposed method was verified by in situ measurements of the studied three‐span concrete bridge. In field testing, static load test and classical impact vibration testing were performed on this bridge for verifying the correctness of the proposed method. The good agreement between predicted deflections by using the scaled flexibility and reference values illustrates the reliability of the proposed method.

中文翻译：

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基于时变频率的后张预应力混凝土桥梁伸缩性识别

动态测试方法已在工程实践中广泛用于研究桥梁的动态特性。但是，只能识别基本的动态参数（即固有频率，阻尼比和未标定的模态形状），这对于状态评估和健康监测是不够的。为了解决这个限制，本文以三跨后张混凝土桥作为试验台。更多有用的结构参数，包括质量归一化模式形状和缩放的柔韧性矩阵，旨在从移动车辆引起的响应中识别出来。为了识别缩放的柔性矩阵，首先需要计算任意缩放的模式形状和质量归一化的模式形状之间的结构缩放因子。在这篇文章中，车桥相互作用（VBI）系统的时变频率用于结构比例因子识别，并且还研究了参数识别误差对计算比例因子的敏感性。通过对所研究的三跨混凝土桥梁进行现场测量，验证了所提方法的有效性。在现场测试中，对该桥进行了静载荷测试和经典冲击振动测试，以验证所提出方法的正确性。通过使用缩放的灵活性和参考值在预测挠度之间的良好一致性说明了所提出方法的可靠性。通过对所研究的三跨混凝土桥梁进行现场测量，验证了所提方法的有效性。在现场测试中，对该桥进行了静载荷测试和经典冲击振动测试，以验证所提出方法的正确性。通过使用缩放的灵活性和参考值在预测挠度之间的良好一致性说明了所提出方法的可靠性。通过对所研究的三跨混凝土桥梁进行现场测量，验证了所提方法的有效性。在现场测试中，对该桥进行了静载荷测试和经典冲击振动测试，以验证所提出方法的正确性。通过使用缩放的灵活性和参考值在预测挠度之间的良好一致性说明了所提出方法的可靠性。