外套钢管混凝土加固RC柱技术研究进展

外套钢管混凝土加固法兼具了增大截面加固法和外包(粘)钢加固法的优点，并利用钢管混凝土组合结构的优良受力特性，可显著改善结构柱的受力性能。近年来，该加固方法得到了大量研究，且该技术在实际工程中亦有诸多应用，表现出了很好的使用前景。为更好地促进该加固技术的理论研究与工程应用，对近年来有关外套钢管混凝土加固RC短柱的轴压、偏压和抗震性能及相应复合加固中长柱轴压性能的研究进展进行综述，分析已有的研究成果，并对后续的研究方向给出建议。研究表明:该复合加固法可以大幅提高被加固RC柱在各种受力工况下的承载力和刚度，并能显著改善其延性；但有关外套钢管混凝土加固柱的力学性能和设计方法等有待深入研究，应进一步通过试验和数值模拟等手段，研究截面形状、二次受力、原柱受损、加固材料和界面等因素对复合加固柱受力性能的影响；加固材料的设计强度取值、加固柱长期力学性能和外套钢管混凝土加固柱的抗震设计方法等应是理论研究及工程应用的关注重点。

Research advances in composite strengthening of RC columns with steel tube and sandwiched concrete jacketing

Steel tube-sandwiched concrete jacketing method combines the advantages of concrete jacketing and steel jacketing methods. Moreover, it has the excellent characteristics of concrete-filled steel tubes, which belongs to composite structures and can significantly improve the mechanical behavior of RC columns. In recent years, numerous research on this retrofit method has been conducted. This technology has also been applied in many practical projects, showing a promising prospect. In order to better promote the theoretical research and engineering application of this technology, the state-of-the-art review of research progress on this composite strengthening technology, including the axial, eccentric, and seismic behaviors of strengthened stub columns as well as axial behavior of strengthened slender columns was presented. The existing research achievements were analyzed, and suggestions for future research directions were proposed. The literature review shows that the ultimate capacity, stiffness, and ductility of strengthened reinforced concrete (RC) columns under different loading conditions are remarkably improved. However, existing research is still inadequate in terms of both the mechanical properties and the design theories. The influence of section shape, preloading, damage of original column, strengthening material, and the interface on mechanical properties of the composite strengthened column should be further studied by means of experiment and numerical simulation. For the theoretical research and engineering application practice, attention is needed for the choice of design strength of strengthening materials, the long-term mechanical performance, and the seismic design method of composite strengthened columns.