大尺寸RPC管-混凝土组合短柱轴压性能研究

Experimental Research on Compressive Performance of Large-Scale Concrete-Filled RPC Tube Columns

将活性粉末混凝土(RPC)制成配有高强螺旋箍筋的预制管,在其内部现浇混凝土,形成新型组合结构——RPC管-混凝土组合柱(CFRT).对5组大尺寸CFRT、1组箍筋约束混凝土柱和1组RPC空管进行了轴压试验,研究RPC管与内部混凝土之间的组合效应,以及配箍率对CFRT轴压性能的影响.结果表明:在受力过程中,外围RPC管能维持其完整性,没有出现明显剥落;CFRT柱的承载力稍高于对应的箍筋约束混凝土柱和RPC空管两者单独的承载力之和;RPC管中配箍率越高,组合柱的抗压性能越好.计算表明,经典的箍筋约束混凝土强度模型低估了CFRT的轴向承载力.基于RPC管损伤和箍筋约束效应,考虑非有效约束区的RPC管对组合柱承载力的贡献,在Mander模型的基础上提出了CFRT承载力模型,该模型的计算结果与试验值基本吻合.

An innovative composite structure, named concrete-filled RPC tube (CFRT), is presented in the paper. In this system, high-strength hoops are arranged in prefabricated reactive powder concrete (RPC) tube, and then concrete is cast in the RPC tube.7 groups of large-scale columns are tested under the axial compression load, including 5 groups of CFRT specimens,1 group of high-strength hoops confined concrete specimens and 1 group of hollow RPC tubes. Composite action between the RPC tube and the internal concrete, and volumetric hoop ratio are the main factors in tests. The results show that the RPC tube of CFRT column only exhibits slightly cracking without any spalling at the peak value. In terms of axial carrying capacity, CFRT column is higher than the sum of hollow RPC tube and corresponding steel-confined column. The compressive properties of CFRT columns improve as the volumetric hoop ratio.The results show that the classic strength model for hoops confined-concrete columns is not fit to predict the load carrying capacity of CFRT specimens. Based on considering the carrying capacity from portion of RPC in ineffectively confined zone and confinement effect on inner concrete, a strength model for CFRT columns is proposed. Predicted values by the proposed model present a good agreement compared to experimental data.