内钢板中空方形钢管混凝土叠合柱轴压力学性能研究

Study on mechanical behavior of square hollow concrete-encased CFST columns with inner steel plate under axial compression

为研究中内钢板中空方形钢管混凝土(CFST)叠合柱的轴压力学性能,以内钢板与钢管的强度和壁厚为参数对8个叠合短柱进行轴压试验,以截面尺寸、钢管内外混凝土强度、钢材强度、纵筋与钢管用钢量分配为参数对81个叠合短柱进行有限元分析,对典型构件受力全过程、各部分接触作用以及承载力进行研究。在美国结构设计规范ANSI/AISC 360-16、欧洲钢结构设计规范BS EN 1994-1-1、GB 50936—2014《钢管混凝土结构技术规范》和T/CECS 663—2020《钢管混凝土加劲混合结构技术规程》的组合柱承载力计算公式中增加内钢板承载力项,得到内钢板中空方形CFST叠合构件的轴压承载力计算式。结果表明:轴压荷载作用下,内钢板中空方形CFST叠合柱钢管外混凝土、内钢板、钢管、纵筋以及核心混凝土能协同工作;内钢板强度与壁厚对构件承载力、延性和刚度影响均较小;截面尺寸和混凝土强度对构件承载力贡献最大,但构件延性随着混凝土强度的增大而降低。在T/CECS 663—2020和ANSI/AISC 360-16的组合柱承载力计算公式中增加内钢板贡献项计算得到的承载力值与试验和有限元结果最为接近。

To clarify the square hollow concrete-encased concrete filled steel tubular(CFST) columns with inner steel plate, a total of 8 square hollow concrete-encased CFST columns with inner steel plates were tested, considering various strengths and thicknesses of steel tubes and inner steel plates. The finite element analysis of 81 composite short columns was carried out, with consideration of various section sizes, concrete strength inside and outside steel tube, steel strength, as well as the amount of longitudinal reinforcement and steel tube. The whole process behavior of the typical specimen, the contact stress between each component, and influence parameters of ultimate capacity under compression were emphatically analyzed. Finally, the load-carrying capacities were obtained through adding the load-bearing capacity of inner steel plate, based on using the modified load-carrying capacities formulas of ANSI/AISC 360-16, BS EN1994-1-1, GB 50936—2014, and T/CECS 663—2020. Results showed that the outer concrete, inner steel plate, steel tube, longitudinal reinforcement, and core concrete of the member can work together under axial compression. The inner steel plate has a marginal influence on the bearing capacity, ductility, and stiffness of the members. The section dimension and concrete strength contribute the most portion of the loading capacity. However, the ductility of the member decreases with the increasing concrete strength. By adding the contribution of the steel plate to the formulas in T/CECS 663—2020 and ANSI/AISC 360-16, the calculated load-bearing capacities are closest to the results obtained from test and FE model.