Title: Understanding Shear-Resistance Mechanisms in Concrete Beams Monitored with Distributed Sensors

Author(s): Jack J. Poldon, Neil A. Hoult, and Evan C. Bentz

Publication: Structural Journal

Volume: 119

Issue: 6

Appears on pages(s): 329-340

Keywords: aggregate interlock; digital image correlation (DIC); distributed fiber-optic strain sensors; large beams; shear; stirrups

DOI: 10.14359/51737148

Date: 11/1/2022

Abstract:
The shear-carrying mechanism in reinforced concrete (RC) has long been uncertain, partly because previously available sensors were insufficient for capturing local behavior. In this study, three large RC beams with stirrups were instrumented with distributed fiber-optic sensors (DFOS) to measure the strain along the full length of the reinforcing bars, while digital image correlation (DIC) was used to measure distributed crack movement to calculate the forces that they transfer. The DFOS measurements along the stirrups showed that the total stirrup force along a shear crack was insufficient to resist the total applied shear. Free-body diagrams (FBD) were constructed along diagonal cracks using the sensor measurements and constitutive relations to investigate if the resulting summation of forces would be in equilibrium, and the results suggest that the main elements of shear resistance have been, at least approximately, identified for the first time with the aid of distributed sensing.