Distributed Reinforcement Strains: Measurement and Application

Distributed reinforcement strain measurements could provide invaluable information for reinforced concrete (RC) model development and evaluation. A technique to measure distributed reinforcement strains using fiber optic sensors in RC elements is developed, which is more cost-effective and less time-consuming than existing methods. Nine RC beams were tested in three-point bending to evaluate the measurements, which were found to be accurate when compared to electrical strain gauges and theoretical predictions. This is the first instance where distributed fiber optic sensors have measured reinforcement strains accurately after cracking; however; strains well above yield were not reliably measured. Relating reinforcement strains with corresponding crack width measurements highlighted differences in how cracks initiate from crack to crack in a single specimen. Lastly, the experimental data were used to evaluate the potential for existing models to be used to predict reinforcement strains from external crack width measurements for RC assessment purposes.