Moving Load Identification with Long Gauge Fiber Optic Strain Sensing

Abstract

Moving load identification has been researched with regard to the analysis of structural responses, taking into consideration that the structural responses would be affected by the axle parameters, which in its turn would complicate obtaining the values of moving vehicle loads. In this research, a method that identifies the loads of moving vehicles using the modified maximum strain value considering the long-gauge fiber optic strain responses is proposed. The method is based on the assumption that the modified maximum strain value caused only by the axle loads may be easily used to identify the load of moving vehicles by eliminating the influence of these axle parameters from the peak value, which is not limited to a specific type of bridges and can be applied in conditions, where there are multiple moving vehicles on the bridge. Numerical simulations demonstrate that the gross vehicle weights (GVWs) and axle weights are estimated with high accuracy under complex vehicle loads. The effectiveness of the proposed method was verified through field testing of a continuous girder bridge. The identified axle weights and gross vehicle weights are comparable with the static measurements obtained by the static weighing.

Determining Magnitudes of Forces at Known Locations through a Strain Gauge Force Transducer

“…Bending stress itself cannot be directly measured, but it can be accurately calculated using the well-established relationship between stress and strain. This relationship is represented in Equation (3), where E denotes Young's modulus, a material property that quantifies the stiffness of a solid, and ε symbolizes the strain, a dimensionless measure of the deformation experienced by the material. By utilizing this fundamental relationship, it is possible to infer the bending stress from the measured strain values [10].…”

“…An alternative method of force determination to strain gauges are Fiber Bragg Grating (FBG) sensors and fiber optics, which are prominently used in structural analysis. One study shows that researchers were able to create a method to identify the load of a moving car on a bridge through the use of long-gauge fiber optic strain responses [ 3 ]. Similarly, another study shows that the use of an FBG sensor is able to measure longitudinal strains when a beam is subjected to multiple loads [ 4 ].…”