UHPC后浇装配式节点抗震性能试验研究

Experimental study on seismic performance of UHPC post-casting assembled joints

在外剪内框结构体系的基础上,研究一种将UHPC运用到装配式节点后浇段、钢筋上下短接的连接方式。为探究该连接方式下节点的抗震性能,进行1个柱节点、1个墙梁节点、2个柱基结点(1个UHPC连接、1个普通混凝土连接)的低周反复试验。在试验基础上利用ABAQUS软件进行有限元模拟,探究钢筋搭接长度对于试件承载力性能的影响。研究结果表明:梁柱节点试件破坏形式表现为梁底混凝土压碎、梁柱交接处裂缝过宽。使用此种连接方式整体耗能能力较好,符合“强柱弱梁、强节点强锚固”的要求。梁墙节点试件发生黏结滑移破坏,梁端耗能能力较差,此种连接方式在墙梁节点中的应用还有待进一步研究。UHPC装配式柱基结点正、负向峰值荷载分别较现浇结点提高近26.5%、15.6%,刚度高于普通混凝土柱基结点,且能减少节点区配箍率,改善节点区域箍筋密集问题。UHPC连接装配式柱基结点和普通混凝土柱基结点的延性系数均在4以上,相差不大。在试验基础上,通过ABAQUS模拟UHPC装配式柱基节点发现,有限元结果和试验结果吻合较好;当试件钢筋搭接长度超过14d,试件的承载力不再随搭接长度改变。综上所述,此种连接方式可大幅缩短钢筋锚固长度,凭借UHPC超强的力学性能使得其抗震性能基本等同现浇,具备一定的实际运用前景。

Based on the research of the shear wall-frame structural system,this paper proposed a connection method in which UHPC was applied to the material of the post-cast joints of precast elements and the lap length of the steel bars was reduced.Low-cycle reserved load tests were carried out to explore the seismic performance of the proposed connection joints(one beam-column joint,one wall-beam joint,and two column-foundation joints).The research results showed that the failure form of the proposed beam-column joint was the concrete at the base of the beam crushed and the crack width at the laminated interface between the precast beam and column was excessive.The overall energy consumption capacity of the joint is good,in line with the requirements of“strong column and weak beam,strong node and weak member”.Besides,the bond-slip damage occurs in the beam-wall joint and the energy dissipation capacity is poor.For the column-foundation connection joints,the positive and negative peak loads for joints with UHPC as the connecting material are 26.5%and 15.6%higher,respectively,than for cast-in-place specimens,and the former have higher stiffness,with ductility factors above 4 for both.Most importantly,the use of UHPC can reduce the hoop ratio in the joint area,thus reducing the hoop density in the joint area.The finite element model is validated based on the test results,and the finite element analysis results show that the load-bearing capacity no longer changes with the lap length when the lap length of the specimen exceeded 14d.Above all,the proposed connection method can significantly reduce the anchorage length of steel bars,and with the excellent mechanical properties of UHPC,the seismic performance is basically equivalent to that of cast-in-place,which has a certain engineering application prospect.