A shear-force-based Bridge Weigh-in Motion approach for simple supported structures

This paper introduces a shear-force-based Bridge Weigh-In-Motion (B-WIM) approach for simply supported structures. Instead of using rosette sensors for shear strain calculation, this method derives shear data from strain measurements taken with strain gauges positioned at the middle of the cross-section, inclined at 45°, near the support. A significant practical advantage of this sensor setup over the rosette configuration is that it requires only one strain gauge per girder to capture the necessary field data. The theoretical basis of this sensor arrangement and its integration into the B-WIM method are thoroughly explained. To evaluate the effectiveness of the proposed approach, its performance is compared to an equivalent bending B-WIM approach using numerical data. Then, in order to assess the proposed approach in practice, a Brazilian simply supported prestressed concrete bridge was instrumented to gather both bending data, based on axial strain in the middle of the span, and shear data near the supports. The results showed that the utilization of the shear based approach provided a substantial reduction in the mean absolute error in axle weight estimation, along with a decrease in the error standard deviation, both in numerical and in real-world B-WIM data. These findings demonstrate the efficacy of the proposed shear based B-WIM approach in improving axle weight estimation for road bridges, while also maintaining accurate predictions for gross vehicle weight. Furthermore, this study is the first in the literature to demonstrate the advantages of using shear data over bending data for B-WIM applications.