活性粉末混凝土（RPC）是一种新型的超高性能水泥基材料，但是RPC的脆性会限制其应用范围。RPC与钢管复合有望得到一种承载力高、延性好的结构形式。本文使用普通硅酸盐水泥、矿物掺合料、钢纤维、砂、高效减水剂等材料配制出了抗压强度超过170 MPa的RPC并研究了RPC强度、应力-应变曲线、弹性模量、泊松比等力学性能。结果表明RPC受压脆性很大，且掺加钢纤维无法改善RPC受压延性，所以必须用钢管约束RPC以缓解其脆性。在研究RPC材料的基本性能的基础上，分析了钢管与核心RPC在钢管RPC短柱轴心受压全过程中的相互作用，及这种相互作用对钢管RPC短柱的轴压承载力和变形能力的影响。结果表明：（1）钢管RPC表现出良好的延性，缓解了RPC脆性大的缺点；（2）由于RPC具有受压峰值应变大、泊松比基本不变、自收缩大、脆性大等特点，钢管对RPC的约束作用小于钢管对普通混凝土的约束作用；（3）钢管RPC短柱常见轴压破坏模式为剪切型破坏。钢管RPC短柱残余承载力与RPC的强度关系不大。将本文与参考文献中86个钢管RPC短柱轴压承载力与中国、美国、日本、欧洲一些现行规程计算结果进行了比较。试算表明，这些针对钢管普通混凝土的规程在计算钢管RPC轴压承载力时大部分偏于不安全。建议设计中仿照美国ACI规程的做法，忽略钢管与RPC间套箍作用以保证安全度。本文还用分离式霍普金森杆研究了RPC及钢管RPC的抗冲击性能。含有钢纤维的RPC具有良好的抗冲击性能，施加钢管约束又会进一步提高RPC抗冲击性能。由于RPC与传统高强混凝土材料在性质上具有相似性，本文结论也可供钢管高强混凝土的相关研究与应用借鉴。
Reactive powder concrete (RPC) is a new type of ultra high performance cementitious composite, but the brittleness limits its application in engineering. It is promising to get a structural type with good bearing capacity and ductility via combining RPC and steel tubes.RPC with the compression strength higher than 170 MPa was prepared using PO 42.5 ordinary Portland cement, mineral admixture, steel fiber, sand and superplasticizer. It is also studied the mechanical behaviors of RPC, such as strengths, stress-strain curves, elastic modulus and Poisson’s ratio. RPC shows enormous compressive brittleness and steel fiber plays little act in improving compressive ductility of RPC, so it is necessary to utilize steel tubes to alleviate the brittleness of RPC.Based on the study on mechanical behaviours of RPC, it is also studied the interaction between steel tubes and the RPC core as well as the interaction’s influence on the bearing capacity and deformability of RPC filled steel tubular (RPCFT) stub columns when the columns are subjected to axial load. The results indicate that: (1) RPCFT stub columns get tremendous ductility and alleviate RPC’s disadvantage of brittle failure. (2) RPC’s mechanical properties, such as large compression peak strain, constant Poisson’s ratio, high autogenous shrinkage and high brittleness, limit the confinement effect between RPC and steel tubes. (3) The common failure mode of RPCFT stub columns under axial compression is shearing failure. The residual strength of RPCFT stub columns is mainly independent from RPC strength.Axial compression test results of 86 RPCFT stub columns acquired from the experimental investigation and literatures are compared with the existing design codes from China, America, Japan and Europe. The comparison indicates that most of the current design codes for normal strength concrete filled steel tubular columns are not safe for RPCFT columns. The confinement between RPC and tubes is suggested to be neglected in the design for convenience and safety, just as the ACI code does.Impact compression tests of RPC and the RPCFT specimens are performed with a split Hopkinson pressure bar (SHPB). RPC specimens with steel fibers show good impact resistance and the impact resistance can be improved furthermore by steel tubes’ confinement.Because of the similarity between RPC and traditional high strength concrete, conclusions derived from this study can also be adopted by researches on high strength filled steel tubular columns.
