Strain-Based Damage-Assessment Method for Bridges under Moving Vehicular Loads Using Long-Gauge Strain Sensing

Abstract

A novel damage-assessment method based on long-gauge strain sensors is presented in this paper. This method is not only suitable for rapid diagnosis of structures, but also it can be applied to long-term structural health monitoring of structures. First, theoretical derivation showed that the damage index strain time history area ratio (STHAR) of bridges under moving vehicular load was only in relation to the local bending stiffness, and it was independent of the weight, velocity, and axle numbers of the vehicular load. Second, the influence of vehicular weight, vehicular velocity, axle number, sensor gauge length, and measurement error on the method was investigated by simulation. In addition, a case study of a lab experiment was also examined. The results show that all damages can be localized accurately, and the mean relative errors between the estimated and actual damage extent were 0.7% and 12.3% for simulation and experiment, respectively. Finally, the robustness of the method was verified by field testing of a real bridge (in the undamaged state). The tendency of the damage index variation was predicted by finite-element method, and the mean relative error between the estimated and actual damage extent was found to be 12.6%.