高温下钢筋与混凝土粘结锚固性能试验研究

Experimental Study on Bond Performance between Steel Bar and Concrete under High Temperature

为研究温度对钢筋与混凝土粘结性能的影响,通过制作30个标准立方体试块、8个温度场试件及15个中心拉拔试件,分别完成了室温(20℃)、100℃、200℃、400℃、600℃下标准立方体试块抗压试验与抗拉劈裂试验、拉拔试件温度场试验及中心拉拔试验。分析了高温作用对混凝土抗压强度与抗拉强度的影响,根据温度场试验研究结果,提出一种简易的高温下中心拉拔试验方法,在此基础上研究了高温下钢筋与混凝土粘结性能退化规律。基于Harajli模型综合考虑温度对粘结强度、峰值滑移及试件破坏模式的影响,提出了高温下钢筋与混凝土粘结-滑移本构模型。试验结果表明:高温下混凝土强度、钢筋与混凝土的粘结强度随温度升高整体呈下降趋势,但在100℃时发生陡降现象,高温下钢筋与混凝土的粘结强度变化趋势与混凝土抗拉强度相近。最后提出了高温下钢筋与混凝土的粘结-滑移本构模型,并验证了模型的适用性。

To investigate the influence of temperature on the bonding performance between steel bar and concrete,thirty standard cube specimences,eight specimens for temperature field test and fifteen central pull-out test specimens were cast. After exposed to 20 ℃,100 ℃,200 ℃,400 ℃,600 ℃,the compression strength and tensile splitting strength of the standard cube specimens,temperature field test of pull-out specimen and pull-out test between rebar and concrete were tested immediately. The influence of high temperature on concrete compressive strength and tensile splitting strength are studied systematically. According to the temperature field test results,a simplified test method for the pull-out test between reinforcing bar and concrete under high temperature is proposed. The degradation law of bond behavior between rebar and concrete under elevated temperature is investigated. A bond-slip constitutive model with considering the influence of temperature on bond strength,slip and failure states is proposed based on Harajli Model. The experimental results show that the strength of concrete and the bond strength between steel bar and concrete under high temperature decline with increasing temperaturegenerally,with a steep reduction at 100 ℃. The variation trend of bond strength under high temperature is similar to the tensile strength of concrete. A bond-slip constitutive model between steel bar and concrete under high temperature is proposed.