杨海峰 杨焱茜 王玉梅 张天宝 黄莹

摘 要：为研究高温后不同冷却方式下混凝土钢筋的粘结滑移性能，对39个高温后混凝土试件进行中心拉拔试验，并完成自然冷却方式下试件的劈裂抗拉强度试验，分析温度和冷却方式对试件峰值粘结应力和峰值滑移的影响，建立了不同冷却方式下峰值粘结应力、峰值滑移与温度的关系式，提出考虑初始温度损伤的粘结滑移全曲线方程，并基于粘结强度理论模型计算了自然冷却方式下的粘结强度理论值。结果表明：随着温度的升高，峰值粘结应力线性下降，500 ℃时粘结强度损失达80.5%，峰值滑移随温度升高呈先减小后增大的趋势，不同冷却方式对峰值粘结应力和峰值滑移的影响不明显;考虑损伤的理论粘结滑移全曲线与试验曲线拟合度较好;采用理论模型计算的粘结强度与试验值较吻合。

关键词：高温;冷却方式;钢筋混凝土;粘结滑移;粘结强度

Abstract： In order to study the concrete-rebar bond-slip performance under different cooling ways after high temperature， a central pull-out test had been carried out on 39 reinforced concrete specimens after high temperature， and the splitting tensile strength test of the specimens under natural cooling had been completed. The effect of high temperature and different cooling ways on peak bond stress and peak slip of the specimens are discussed in this paper. The calculation equations between peak bond stress， peak slip and temperature have been established， and the full curve equation of bond-slip considering initial temperature damage has been proposed. Based on the theoretical model of bond strength， the theoretical value of bond strength under natural cooling has been calculated. The results show that as the temperature increases， the peak bond stress decreases linearly. At 500 ℃， the bond strength loss reached 80.5%， and the peak slip showed a trend of first decreasing and then increasing with growth of temperature. The effect of different cooling ways on peak bond stress and peak slip is not obvious. The theoretical bond-slip full curves considering damage has a good fit with the test curves; The bond strength calculated by the theoretical model is in good agreement with the test value.

Keywords：high temperature; cooling ways; reinforced concrete; bond-slip; bond strength

隨着中国经济的迅速发展，城市高层建筑密度大、易发生重大火灾。钢筋混凝土结构在火灾后会出现不同程度的损伤，从而导致建筑物倒塌，造成经济损失，给社会安全带来巨大威胁。粘结是钢筋混凝土间一种复杂的相互作用，足够的粘结强度是钢筋混凝土发挥良好工作性能的基础，因此，研究钢筋混凝土在火灾后的粘结性能退化十分必要。已有许多学者研究温度对混凝土力学性能[1]和钢筋混凝土粘结性能的影响，Bi等[2]和Karolina等[3]研究发现，温度……