The unit influence line of a structure reflects its behaviour and changes in response to damage that may occur. An iterative algorithm is presented in this paper to obtain the shape of the instantaneous influence line of a bridge together with the relative axle loads of trucks passing overhead. One great advantage of this approach is that the need for sensor calibration with pre-weighed trucks can be avoided. The only initial information needed are the measurement data and a preliminary estimate of influence line based on engineering judgement. The concept of a so-called population unit influence line is also presented. This is an influence line that is found from a population of trucks instead of a single vehicle. An illustrative example is presented, where strain data have been collected on a reinforced concrete culvert. As well as the robustness of the proposed algorithms, the influence of temperature on the results is demonstrated. The sensitivity of the population influence line to temperature shows that it is likely to be equally sensitive to loss of stiffness in the structure.

中文翻译：

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使用桥梁的单位影响线跟踪其状况的变化

结构的单位影响线反映了其行为和对可能发生的损坏的响应变化。本文提出了一种迭代算法来获得桥梁的瞬时影响线的形状，以及通过上方的卡车的相对轴荷。这种方法的一大优势是可以避免使用预先称重的卡车进行传感器校准的需求。唯一需要的初始信息就是测量数据和基于工程判断的影响线的初步估计。还提出了所谓的人口单位影响线的概念。这是一条影响线，可以从大量卡车而不是单个车辆中找到。给出了一个说明性示例，其中已在钢筋混凝土涵洞上收集了应变数据。以及所提出算法的鲁棒性，证明了温度对结果的影响。总体影响线对温度的敏感性表明，它可能对结构刚度的损失同样敏感。