装配式圆钢管约束混凝土柱的轴压性能

为了研究钢套管及套筒连接装配式圆钢管约束混凝土柱轴压性能，基于试验研究结果，对钢套管及套筒连接装配式圆钢管约束混凝土柱轴压性能进行了有限元分析. 首先通过有限元建立了现浇式和装配式圆钢管约束混凝土柱模型；然后从承载力-平均纵向应变关系曲线、钢管应力、钢筋应力和混凝土应力方面对比了现浇式与装配式柱的轴压性能；其次分析了装配式柱变形形态及受力机理；最后提出了装配式柱轴压承载力计算方法. 研究结果表明:与现浇式柱相比，装配式柱也具有良好的轴压性能和延性性能，钢管及钢套管对核心混凝土的约束作用更强，轴压承载力提高幅度为1.94%～6.17%；增加钢管厚度对提高装配式圆钢管约束混凝土柱轴压承载力最有效，提高幅度达59.15%，增加箍筋间距对其轴压承载力影响较小，减小幅度为2.91%；钢管纵向应力在靠近钢套管与钢管连接处较大，钢管环向应力在钢管通缝上、下附近区域较大，在钢套管装配处也较大；所提装配式柱轴压承载力公式计算值（N_uc）与有限元值（N_uf）、试验值（N_ut）的比值均值分别为0.964、1.014，方差分别为0.003 5、0.002 9. 

Axial Compressive Properties of Prefabricated Circular Steel Tube Confined Concrete Columns

A finite element analysis based on test results was carried out to study axial compressive performances of the prefabricated circular steel tube confined concrete columns connected with steel sleeve and straight thread sleeve. First, finite element models of cast-in-situ and prefabricated circular steel tube confined concrete columns were established. Then, axial compressive performances of the cast-in-situ and prefabricated columns were compared in terms of the bearing capacity–average longitudinal strain curves, steel tube stress, rebar stress, and concrete stress; the deformation pattern and mechanism of prefabricated columns were analyzed. Finally, a calculation method of axial compressive capacity of prefabricated columns was proposed. Results show that the cast-in-situ columns and the prefabricated columns both have good mechanical and ductility properties; the steel tube and steel sleeve have strong confinement effect on the core concrete and the axial compressive bearing capacity was increased by 1.94%?6.17%. Increasing the thickness of steel tube can effectively improve the axial compressive bearing capacity by 59.15% at most, while increasing the stirrup spacing has little effect on the axial compressive bearing capacity, merely a reduction of 2.91%. The longitudinal stress of the steel tube is larger in the area near the connection between the steel tube and steel sleeve, while the circumferential stress of the steel tube is larger in the area near the upper and lower circular sutures of steel tube and is also larger at the assembly of steel sleeve. The average ratio of calculated value (N_uc) to finite element value (N_uf) and the average ratio of N_uc to test value (N_ut) is 0.964 and 1.014, with variance of 0.003 5 and 0.002 9, respectively, where N_uc, N_uf and N_ut denote respectively the values from formula calculation, finite element calculation, and test of the prefabricated column axial compressive bearing capacity.