混凝土植筋界面结合机理试验研究

Experimental research on interface action behavior of adhesive steel bar in concrete

针对两种品种的胶和两种粘结长度进行了混凝土植筋试件的约束拉拔试验。所有试件均发生了钢筋与胶体之间的界面破坏,与试验预期目标一致。但部分试件出现了钢筋屈服现象,说明植筋粘结长度过长。试验结果表明,钢筋-胶体界面结合力与滑移的关系可以简化为三阶段模型:粘结阶段、滑移阶段、拔出阶段。粘结阶段为线弹性段,界面结合力以化学粘结力为主,其特征是钢筋自由端位移为零。滑移阶段为抛物线段,界面结合力以机械啮合力为主。拔出阶段为下降段,界面结合力以摩擦力为主。通过对试验结果的回归分析可得到钢筋-胶体界面粘结滑移本构关系。

The experimental research is based on adhesive steel bars in concrete under tensile load with two fixing products and two bonding lengths. Interface failure between steel bar and adhesive layer happened as expected in every test element. For some test elements with longer bonding length, steel yields before the tensile force reaches the ultimate load. The experimental result shows that the bond-slide relation for the interface between steel bar and adhesive layer could be simplified as three phase model, bonding phase, sliding phase and, pull-out phase. The bonding phase is elastic phase with chemical bonding force as main part of interface action, and there is no slide at the free end of steel bar in bonding phase. The sliding phase is non-linear phase with interlock force as main part of interface action. The pull-out phase is near-linear down phase with friction force as main part of interface action. The formula of bond-slide relationship for the interface between steel bar and adhesive layer could be got based on the experimental result.