RPC预制管混凝土组合柱组合效应试验研究

配有高强螺旋箍筋的活性粉末混凝土(RPC)预制管内浇筑混凝土,形成一种新型组合结构——RPC预制管混凝土组合柱(CFRT).对9个不同箍筋间距的CFRT,3个箍筋约束混凝土柱和3个RPC空管开展轴向抗压试验,研究RPC管与内部混凝土之间的组合效应,以及箍筋间距对CFRT轴压性能的影响.结果表明:在荷载峰值下,组合柱中的RPC管没有出现明显的剥落现象,构件截面较为完整;CFRT柱的承载力显著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,在承载力上实现了超叠加;CFRT中配置的箍筋间距越小,组合柱的抗压性能越好;基于Mander模型和相应的简化,对CFRT的组合效应进行了分析,RPC管对组合柱的轴向承载力贡献在0.22~0.26之间,且随箍筋间距的增大而有提高的趋势,并提出了CFRT轴向承载力计算方法.

Experimental Research on Composite Action of Concrete-filled RPC Tube under Axial Load

An innovative composite structure, named concrete-filled RPC tube (CFRT), was presented in the paper. In this system, high-strength stirrups are arranged in prefabricated reactive powder concrete (RPC) tube, and concrete is then casted into RPC tube. Total fifteen large-scale columns were designed and conducted for axial compression test, including nine CFRT specimens, three high-strength stirrup confined concrete (HSCC) specimens and three hollow RPC tubes. Composite action between the RPC tube and internal concrete as well as the spiral stirrup spacing was considered as the main factors in tests. The results show that only slightly cracking without any spalling occurs at the RPC tube of CFRT column when axial load approaches its peak value. Meanwhile, the axial load-carrying capacity of CFRT column is higher than the sum of that of hollow RPC tube and internal concrete, indicating this composite system realizes the superposition effect. The compressive properties of CFRT columns are also improved with the decrease of spacing of stirrups. Moreover, based on Mander model and the corresponding simplifications, contribution ratio of RPC tube for load-carrying capacity of CFRT columns was quantified, and its value increased from 0.22 to 0.26 with the increasing stirrup ratio. Furthermore, a calculation method for load-carrying capacity of CFRT was proposed.