Distributed fiber-optic sensing of reinforced concrete arch ribs to monitor plastic hinge formation

This research aims to evaluate the potential of fiber-optic sensing of reinforced concrete (RC) structures for improved understanding of damage progression in laboratory testing and for rapid postearthquake damage assessment of real structures. A testing campaign was conducted on RC specimens with different detailing options for RC arch bridges, which experience high axial load and bending moment during earthquakes. Several types of fiber-optic cables were embedded within the four RC arch rib specimens, which were subjected to varied axial loads followed by cyclic lateral loading. The fiber-optic cables enable detailed distributed strain measurement within the RC specimen throughout the testing, as well as the residual distributed strain after each load cycle. Results provide new insight regarding the progression of cracking and the measurement of plastic hinge formation; results are compared with previous plastic hinge models. The residual strain measurements led to the development of a novel damage index that enables correlation of residual distributed strain with the maximum drift experienced during cyclic loading; this correlation is essential to evaluate potential damage when continuous fiber-optic sensing is not economically feasible and only postearthquake fiber-optic strain data are available. The findings from the testing will not only have a direct impact on the design of RC arch ribs but also pave the way for distributed fiber-optic sensing-driven postearthquake damage assessment.