Closure to 'Experimental Study on Bond Behavior of Deformed Bars Embedded in Concrete Subjected to Biaxial Lateral Tensile Compressive Stresses' by Xue Zhang, Zhimin Wu, Jianjun Zheng, Yu Hu, and Qingbin Li

摘要

The authors would like to thank the discusser for his interest in the paper and valuable comments. The authors' responses to the comments are addressed subsequently: 1. As noted by the discusser, the main bond parameters, i.e., ultimate and residual bond strengths and slip at the peak bond stress, were analyzed against ζ = p_t/f_t + p_c/f_(cu) in this paper, whereas the separate analysis on the basis of each lateral tensile and compressive stress was not shown directly. To investigate the effect of lateral compressive stress on the bond strength, the specimens with C40 concrete subjected to a given lateral tensile stress, i.e., p_t/f_t =0.1, and different lateral compressive stresses, i.e., p_c/f_(cu) =0.1, 0.2, 0.3, 0.4, and 0.5, are considered. The results are shown in Fig. 1(a), which indicates that τ_u//f_(cu)~(1/2) decreases with an increase in p_c. As for the effect of lateral tensile stress on the bond strength, the same type of specimens subjected to a given lateral compressive stress, i.e., p_c/f_(cu) =0.1, and different lateral tensile stresses, i.e., p_t/f_t =0.1, 0.3, and 0.5, are considered. The results are shown in Fig. 1(b), which indicates that τ_u/f_(cu)~(1/2) decreases by increasing p_t. The same is true for other combinations of lateral stresses. Therefore, the paper concluded that "It can be seen from Appendices Ⅰ, Ⅱ, and Ⅲ that, when lateral tensile-compressive stresses are applied, the bond strength ratio τ_u/f_(cu)~(1/2) decreases with an increase in lateral tensile or compressive stress." According to Kupfer et al. (1969), concrete subjected to the biaxial tensile-compressive stresses p_t and p_c fails once p_t/f_t + p_c/f_(cu) = 1, where f_t and f_c are the tensile and compressive strengths of concrete. This implies that the failure of concrete is closely related to the coupling effect of lateral stresses, i.e., p_t/f_t + p_c/f_(cu), but independent of the loading path, as shown in Fig. 2. Therefore, it is reasonable to use the parameter ζ = p_t/f_t + p_c/f_(cu) to evaluate the effect of lateral tensile-compressive stresses on the bond strength. In addition, because a small embedment length was adopted in this study, the Poisson's effect of deformed bars is negligibly small.