再生粗骨料含量对钢管再生混凝土粘结强度及失效性态的影响研究

为了探究再生粗骨料取代率对钢管与再生混凝土界面粘结强度及破坏机理的影响, 设计15个圆钢管再生混凝土和9个方钢管再生混凝土短柱试件, 以混凝土强度等级和长径比为变化参数分组进行取代率的影响分析. 通过推出试验, 获取荷载-滑移曲线的特征点参数, 回归得到极限粘结强度的计算公式. 从界面耗能、粘结抗剪刚度、损伤等角度分析了取代率对其内在失效机理的影响. 研究结果表明:极限粘结强度拟合公式计算值与试验实测值吻合较好；再生粗骨料取代率变化对钢管再生混凝土接触界面粘结失效过程的耗能能力影响不大；而界面弹性粘结剪切刚度却随着取代率的增加而降低；剪切刚度退化速度则相反, 随着取代率的增加而加快；再生粗骨料粘附的水泥基和内部裂纹会加快钢管再生混凝土界面的粘结损伤过程.

INFLUENCE OF RECYCLED COARSE AGGREGATE CONTENT ON BOND STRENGTH AND INVALIDATION MECHANISM BETWEEN STEEL TUBE AND RECYCLED AGGREGATE CONCRETE

In order to explore the influence of recycled coarse aggregate (RCA) replacement ration on the bond strength and failure mechanism of steel tube and recycled aggregate concrete interface, 15 recycled aggregate concrete-filled circular steel-tube short columns and 9 recycled aggregate concrete-filled square steel-tube short columns were designed for the push-out test. Two parameters of concrete strength grade and length-diameter ratio were grouped so as to analyze the effect of RCA replacement ration. Based on the test, the characteristic point parameters in load-slip curves were obtained and ultimate bond strength calculation formulas were fitted. The influence of RCA replacement rate on the invalidation mechanism was researched in interface energy consumption, bonding shear stiffness and damage. The results show that there is a good agreement between formula calculated values and test measured values. There is no efficient effect of RCA replacement ration changing on the interface energy dissipation during the process of bond failure. The interface elastic bond shear stiffness decreases with the increasing of RCA replace ration, and the rate of stiffness degradation behaves different. Due to the adhesive cement matrix and internal cracks of RCA, they will accelerate the bond damage process on the interfacial between steel tube and RAC.