Experimental Study on Bond Behavior of Deformed Bars Embedded in Concrete Subjected to Biaxial Lateral Tensile Compressive Stresses: Fid-Bau Portal

Experimental Study on Bond Behavior of Deformed Bars Embedded in Concrete Subjected to Biaxial Lateral Tensile Compressive Stresses

Zhang, Xue / Wu, Zhimin / Zheng, Jianjun / Hu, Yu / Li, Qingbin

Abstract

The bond behavior of deformed reinforcing bars, which is important to the assessment and design of reinforced concrete structures, is greatly influenced by the stress state in concrete. Because the effect of biaxial lateral tensile-compressive stresses on the bond behavior of deformed bars is seldom studied, an experimental investigation is presented in this paper. A total of 252 pull-out specimens with different strengths of concrete, bar diameters, and combinations of lateral tensile-compressive stresses were included in the test. The results show that the failure mode of specimens with deformed bars is influenced by the strength of concrete, ratio of the cover depth to bar diameter $c / D$ , and the coupling effect of lateral stresses $ζ (= p_{t} / f_{t} + p_{c} / f_{c u})$ . The bond strength and the slip at the peak bond stress decrease by increasing $ζ$ , whereas the deteriorating ratio depends on the strength of concrete and $c / D$ for specimens failed by pull-out and splitting, respectively. Regardless of $ζ$ , the ratio of the residual and ultimate bond strength for the specimens in pullout failure basically keeps constant. An empirical bond stress-slip relationship is proposed. For different strengths of concrete, bar diameters, and combinations of lateral stresses, the proposed bond stress-slip relationship is in good agreement with experimental results.