植筋混凝土锚固性能试验研究

Experimental study on anchorage bahavior of post-installed bar in concrete

植筋锚固性能是影响混凝土补强加固效果的重要因素。综合考虑钢筋直径、混凝土强度、锚固长度、植筋孔径和植筋方式对钢筋锚固性能的影响,采用102个后植筋混凝土试件和18个普通钢筋混凝土对比试件,共120个试样进行了室内拉拔试验。试验结果表明:混凝土试块主要呈现出胶-混界面破坏、钢筋屈服破坏和混凝土劈裂三种破坏形式;钢筋直径、混凝土强度、锚固长度、植筋孔径是影响钢筋平均极限拉拔力与胶-混界面极限平均粘结力的重要因素;采用后植筋补强混凝土强度可以达到与预埋筋相同的效果。通过理论分析建立了混凝土劈裂破坏时钢筋极限拉拔承载力计算公式和植筋界限孔径公式,计算值与试验结果吻合。试验结果与理论分析为混凝土植筋锚固性能的分析与评价提供了参考依据。

The bonding property of post-installed bar in concrete is an important factor to influence strengthening effect of reinforced concrete.120 specimens of installed bar,including 102 specimen of post-installed bar and 18 specimen of embedded bar,were tested by pull-out test.Comparative analysis considering diameter of steel bar,tensile strength of concrete,anchoring depth of steel bar,hole diameter and styles of installing bar was conducted.The experimental results show that the bonding property of post-installed bar is significantly influenced by steel bar,tensile strength of concrete,anchoring depth of steel bar and diameter of hole.The ultimate average pull-out force of steels in specimen of post-installed bar and specimen of embedded bar are nearly equal.Three kinds of failure models are obtained in this paper,that is,pull-out of installed bar from concrete,tensile failure of installed bar and concrete split.Furthermore,on the basis of analyzing failure mechanics for concrete split,the empirical formulae for determining ultimate pull-out force and limit hole diameter are established.The experimental results can be useful for analyzing and evaluating bonding behaviors of post-installed bar in concrete.