Reinforcement Strain and Bond Stress in RC Tensile Members Using Strain Gauges

Since the dawn, reinforced concrete (RC) is deeply associated with the term infrastructure development throughout the world. Being a composite material, the mechanics of RC structures holds one of the most complex issue, the interaction between concrete and reinforcement. To understand the relation between these two extremely important but contrasting materials, accurate knowledge and understanding of concrete and the embedded reinforcement are essential. Focusing on the same, experimental studies have been carried out on reinforced concrete short tensile elements, thanks to its realistic strain transfer mechanism. Double pull-out tests were performed with two rectangular RC elements of identical cross-section but different lengths. Relying on the modern technology, multiple tensor strain gauges were installed inside the reinforcement core using the special technique to prepare the modified reinforcement for extracting the strain distribution data from the core of the embedded rebar, under various load levels. Extracted strain profiles can be used efficiently in the field of structural health monitoring and further to study the bond-slip relationships. For the purpose of validation, the experimental results were compared with the bond-slip model provided in the Model Code 2010. Beside the study of serviceability performance, extracted strain distribution is essential for other structural assessments such as crack monitoring and tension stiffening creep-shrinkage behavior. Along with the innovative technique of explicit strain measurement from the core of the embedded reinforcement, this study enables future researches related to bond interaction. No doubt in the study of bond- slip, limited results have been published based on the double pull-out test comparing to the conventional pull- out test. So a successful strain monitoring and bond-slip assessment from the present study can be a step forward toward the innovative and smart development of future research in the fundamentals of RC, concerning a resilient structure, its strength, and security.