高温后钢筋再生混凝土轴压短柱受力性能试验研究

Mechanical behavior of reinforced recycled aggregate concrete short columns under axial compression after high temperature

为了研究高温后钢筋再生混凝土轴压短柱的受力性能,以再生粗骨料取代率、温度、最高温度持时、混凝土强度和箍筋间距为变化参数,设计40个试件(其中高温后试件32个、常温对比试件8个)进行静力加载试验。观察了高温后钢筋再生混凝土轴压短柱的破坏形态,获得了其承载力、刚度、位移延性系数和耗能等力学性能指标,并对不同变化参数试件的力学性能指标进行分析,探讨了高温后钢筋再生混凝土轴压短柱的承载力计算方法。研究结果表明:随着温度升高,钢筋再生混凝土柱的外观颜色逐渐由青灰色转变为灰白色,其质量烧失率逐渐增大,试件的承载力和初始刚度逐渐降低;再生粗骨料取代率的大小对高温后钢筋再生混凝土轴压短柱的承载力和初始刚度的影响不大;混凝土强度等级越高的试件,其遭受高温后的承载力和初始刚度也越大;最高温度持时和箍筋间距的变化对高温后钢筋再生混凝土轴压短柱力学性能影响不大。

The mechanical behavior of recycled aggregate concrete axial compression short columns after high temperature was investigated. Five parameters including recycled coarse aggregate replacement ratio, high temperature,the highest temperature duration,concrete strength and stirrup spacing were taken into consideration.Based on the static load tests of 32 specimens after high temperature and 8 contrastive specimens at ambient temperature,the failure mode was observed and the ultimate bearing capacity,rigidity,ductility and energy dissipation were obtained. Furthermore,the effects of different parameters on mechanical performance index mentioned above were analyzed. A calculation means was provided which can be used to calculate the ultimate bearing capacity of recycled aggregate concrete axial compression short columns after high temperature. The results indicate that after increasing the temperature,concrete surfaces change from cinereous to grey,and the quality ignition loss rate increases gradually. It is shown that the ultimate bearing capacity and the initial rigidity decrease with an increased temperature. With an increased replacement ratio,the bearing capacity and the initial rigidity vary slightly. It also indicates that the bearing capacity and the initial rigidity increase with higher concrete strength. However,difference of the highest temperature durations have little influence on behaviors of specimens as well as stirrup spacing.