改性钢管全再生粗骨料混凝土短柱的轴压试验

Experimental study on modified recycled aggregate concrete-filled steel tube columns under axial compression

为了最大化利用再生骨料,以硅粉和钢纤维掺量为主要变化参数设计了20个圆形和方形截面钢管全再生粗骨料混凝土短柱构件进行轴压试验,观察了短柱的受力全过程和破坏形态,获取了构件的荷载―变形全过程曲线,分析了硅粉和钢纤维掺量对其承载性能的影响,试验结果表明:混凝土中的粗骨料全部采用再生骨料会降低钢管再生混凝土柱的峰值承载力及峰值应变,可以采用硅粉的填充效应及活性和钢纤维对裂缝的内部约束来改善钢管全再生骨料混凝土柱的性能,经改性后的钢管全再生骨料混凝土柱的性能和普通钢管混凝土柱的性能相当,硅粉掺量为10%、钢纤维体积掺量为1.5%的钢管全再生骨料混凝土的峰值承载力超过了普通钢管混凝土柱。并采用现有计算理论及规程计算公式对构件的承载力进行了计算和比较,得到各规程在计算钢管全再生骨料混凝土承载力时的适用性,规程EC4和试验数据更接近。

In order to make full use of recycled aggregate,20 specimens with circular and square cross sections were designed to be tested,and the dosage of silica powder and content of steel fiber were regarded as the major variable parameters.Through the experiment,the entire compress process and failure modes of all specimens were observed,and load-strain curves of the specimens were obtained.The test results indicate that the ultimate axial load and corresponding strain of the concrete-filled steel tube columns would decrease after the replacement of natural coarse aggregate with 100% recycled coarse aggregate.The filling effect and pozzolanic action of silica powder and the confinement effect of steel fiber could be used to improve the performance of concrete-filled steel tube columns with 100% recycled coarse aggregate,and the performance of modified columns was i-dentical to that of common columns.The column with 10% cement replaced by silica powder and1.5% volume fraction of steel fiber has a higher ultimate axial load than that of common columns.In addition,the applicability of present theory and formula from different codes to calculate the bearing capacity of the specimens was obtained based on the comparison of calculated results.The results obtained by EC4 are more close to the experimental results.