考虑初应力影响的钢管混凝土叠合柱在长期荷载作用下的力学性能研究

Both preload and long-term loading can possibly impose significant effects on the behaviour of concrete filled steel tube reinforced concrete (CFSTRC) columns, which may result in structural failure. However, the research on the effects of preload and long-term loading on CFSTRC columns is still quite limited so far. Thus, it has important theoretical and practical significance to carry out the research work on the behaviour of CFSTRC columns under long-term sustained loading with preload effects considered. This project is an attempt to study the mechanism and design method of CFSTRC columns subjected to long-term sustained loading with preload effects considered. A series of tests on the CFSTRC columns with preload effects considered under long-term sustained loading will be carried out, and the behavior of specimens, such as failure modes, load-bearing capacity and deformation performance will be then investigated. The analytical model of CFSTRC columns under sustained loading with preload effects considered will be established by using finite element method. By using the finite element model, the mechanism of CFSTRC columns with preload effects considered subjected to long-term sustained loading will be analyzed, where the force redistribution between concrete and steel, and the interactions between outer concrete, core concrete and steel tube will be clarified. Meanwhile, some important factors, such as materials property, load age, steel tube ratio, slenderness ratio, preload ratio and sustained load level on the behaviour of CFSTRC columns will be analyzed. Based on the parametric results, the simplified model to calculate the ultimate bearing capacity of CFSTRC columns with preload effects considered under long-term sustained loading will be proposed.

初应力和长期荷载作用会对钢管混凝土叠合柱的力学性能产生较大的影响，可能导致结构的失效，而以往尚未见相关研究的报道，因此，开展该方面的研究工作具有重要的理论意义和工程应用价值。 本项目深入研究考虑初应力影响的钢管混凝土叠合柱在长期荷载作用下的工作机理和设计方法。建立考虑初应力影响的钢管混凝土叠合柱在长期荷载作用下受力全过程分析的有限元模型，并开展考虑初应力影响的叠合柱在长期荷载作用下力学性能的试验，研究结构构件的破坏模态、承载能力和变形特性的变化规律。深入研究考虑初应力影响时长期荷载作用对叠合柱力学实质的影响，明晰受力全过程中截面内力重分布机理、以及钢管与管内外混凝土之间的相互作用。研究重要影响因素，如材料强度、加载龄期、含钢管率、长细比、初应力系数、长期荷载比等的影响规律；在此基础上提出考虑初应力影响的钢管混凝土叠合柱在长期荷载作用下的承载力计算方法，为有关设计规程的制定提供依据。