CFRP-钢管RPC短柱的轴压试验研究

Experimental Investigation on Axial Compression of CFRP Confined RPC Filled Steel Tube Short Column

对12根核芯为100~160MPa强度等级的活性粉末混凝土(RPC),外部约束为壁厚2、4mm的钢管和2层碳纤维增强复合材料(CFRP)的CFRP钢管RPC(CRST)短柱进行试验研究.结果表明:与普通混凝土相比,RPC的抗压强度更高,其在无外部约束状态下的脆性更加明显,达到极限承载力时对应的应变较大;CRST短柱主要发生剪切破坏和端部压缩外鼓破坏,其载荷位移曲线可划分为线弹性阶段、弹塑性阶段、破坏阶段和平台阶段;考虑CFRP和钢管对核芯RPC的双重约束,提出了用影响系数IF表示CFRP和钢管对极限承载力的提高程度,并通过线性回归拟合得到了IF的表达式;同时假设CRST短柱在到达极限承载力时钢管已屈服,采用极限平衡分析的方法对CRST短柱的极限承载力进行了简化计算,得到了与试验结果吻合良好的拟合公式.

The experimental study was carried out on 12 carbon fiber reinforced composite(CFRP)confined reactive powder concrete(RPC)filled steel tube(CRST)short columns.The core of the short columns was RPC with a strength of 100160MPa,and the external constraints were steel tubes with a wall thickness of 2 or 4mm and two layers of CFRP.The results show that compared with ordinary concrete,RPC material has higher compressive strength,more obvious brittleness in the state of no external constraints,and larger corresponding strain when the ultimate bearing capacity is achieved.Failure modes of CRST short columns under axial compression occur shear failure and end compression drum failure.The load-displacement curves of CRST short columns are mainly divided into linear elastic stage,elastoplastic stage,failure stage and platform stage.Considering the double constraint of CFRP and steel pipe on core RPC,the influence coefficient IF is proposed to represent the improvement degree of CFRP and steel pipe on ultimate bearing capacity,and the expression of IF is obtained by linear regression fitting.At the same time,it is assumed that the steel pipe has yielded when reaching the ultimate bearing capacity of CRST short columns.The ultimate bearing capacity of CRST short columns is calculated by the method of limit equilibrium analysis.A fitting formula is obtained which is in good agreement with the test results.