Measuring Support Reactions in a Composite Model Bridge Using Distributed Fiber Optic Sensing

This paper investigates the potential of using distributed fiber optic sensing (DFOS) to evaluate load distribution and support reactions within a statically indeterminate structure. A multibeam two-span composite model bridge was built and instrumented with DFOS. Three different loading scenarios (full width, concentrated, and offset) and two different slab thicknesses were used to investigate their impact on load distribution and reactions forces. Disturbed regions near the supports meant that shear forces, and thus reactions, could not be measured in this region and thus had to be extrapolated. Two extrapolation techniques (linear and second order) were developed and evaluated using a grillage model. The second-order fitting technique provided more accurate reaction forces for the grillage model and was then used with the distributed strain data from the model bridge to estimate the reactions. Challenges associated with the scale of the experiment were identified that should result in better performance on full-scale structures.

Automated summary

This paper explores the potential of using distributed fiber optic sensing (DFOS) to assess load distribution and support reactions in statically indeterminate structures. A multibeam two-span composite model bridge was built and equipped with DFOS instrumentation. Different loading scenarios and slab thicknesses were used to examine their effects on load distribution and reaction forces. The challenge of measuring shear forces and reactions near the supports was overcome by developing and evaluating extrapolation techniques. The study demonstrates the accuracy and applicability of DFOS technology for estimating reactions in real-life structures.