高温后钢管超高强石渣混凝土短柱的轴压性能

Experimental Study of Behaviors of GSHSCUS-filled Steel Tubes Short Columns after High Temperature

低碳超高强石渣混凝土是作者利用本地原材料以低至350 kg.m-3的水泥消耗量自主研发的新型环境友好型混凝土.本文以试件的直径、径厚比、混凝土强度等级、混凝土类型和温度为试验参数进行了12根试件的轴心受压试验,考察了高温后钢管超高强石渣混凝土短柱在轴心受压时的破坏形态,研究高温后钢管超高强石渣混凝土短柱的力学性能和剩余承载力.试验结果表明:在试验参数范围内,高温后试件的荷载-平均应变关系曲线与常温下的曲线相似,都可以分为弹性阶段、弹塑性阶段、承载力下降段和承载力回升段等4个阶段;但高温后的曲线的弹性变形阶段明显缩短,弹性极限荷载与极限荷载的比值减小,刚度明显蜕化;峰值应变增大,而最大压缩应变明显减小;高温后钢管超高强石渣混凝土的剩余承载力系数比钢管聚丙烯纤维超高强石渣混凝土的大,而高温后这两者的剩余承载力系数均比钢管混凝土的高,并分析了其机理.

GSHSCUS is a new kind of environmentally friendly concrete with the strength over 100 MPa,which were developed by the authors by using local materials at the lower consumption of ordinary Portland cement of 350 kg·m-3.Based on the experimental studies of 12 GSHSCUS-filled steel tubes short columns with four different parameters including concrete strength,diameter,diameter-thickness ratio and concrete grade,this paper describes the failure modes of the short columns after the action of high temperature and under the axial load,and tries to discover the general regularity.It is found that within the factor scope of this test,the load vs.average strain curves of the specimens may be divided into four stages ： elastic deformation,elastoplastic deformation,descent process and recovery process of its carrying capacity,which is similar to that at room temperature;but elastic deformation stage is shorter with the lower stiffness and the ratio of elastic limiting load to ultimate load being lower,and with the peak strain increasing and the maximum strain decreased.The results indicate that the residual load capacity factor of GSHSCUS-filled steel tubes column after the high temperature is higher that of PFRGSHSCUS-filled steel tubes column,both of which are higher than that of CFST;their mechanisms after high temperature are also analyzed.