Numerical Evaluation of Bond Behavior of Ribbed Steel Bars or Seven-wire Strands Embedded in Lightweight Concrete

The bond-slip relationship between concrete and steel is significant in evaluating the nonlinear behavior of reinforced concrete structures. The force transmitted by the bond in reinforced concrete structures was studied numerically in high-strength, lightweight concrete with ribbed reinforcing steel bar or seven-wire strand, using ATENA 3D software. The first part of the study was a validation of the model based on the actual results of standardized pull-out tests using the software. Subsequently, the bond behavior was studied, where a four-point static bending test was modeled based on the real bond-slip relationship of the pull-out test. It was deduced that the ATENA 3D software can simulate the experimental tests and provide meaningful results. In addition, inferred from the numerical modeling, the maximum crack width and the mid-span deflection of the reinforced concrete beam increased when the bond stress between the concrete and the reinforcing steel bars was decreased. When a high amount of reinforcement (two strands) was used, concrete failure occurred before the strands yielded. However, further increase of the bond stress also decreased the maximum crack width and mid-span deflection. The failure occurred due to the increase in the strand yielding point by using one strand as a reinforcement of the beam.