内置CFRP圆管的方钢管混凝土短柱力学性能研究

Mechanical behavior of concrete filled square steel tube short columns with inner CFRP circular tube

碳纤维增强聚合物(CFRP)复合材料因其自身强度高、质量轻、吸能抗震、施工便捷等优点在结构加固尤其是在钢管混凝土(CFT)结构中得到广泛的应用。基于考虑中间主应力影响、拉压强度差的适用于各种材料的复杂应力状态下的双剪统一强度理论,考虑内置CFRP管对核心混凝土的约束影响,引入强度折减系数和厚边比影响的等效约束折减系数,对内置CFRP管的方钢管混凝土短柱这种新型构件轴压时的受力性能进行了理论分析,分析了中间主应力、CFRP配置率以及材料强度参数取值等对承载力的影响,推导出内置CFRP管方钢管混凝土短柱的轴压承载力公式,并与试验结果对比,验证了公式的正确性。结果表明:内置的CFRP管可以有效约束核心混凝土,这种结构充分地发挥了CFRP、混凝土和钢材三种材料的优点,理论公式为内置CFRP管的钢管混凝土短柱的极限承载力分析提供了一定的理论基础,并为钢管混凝土结构的优化设计提供可靠的理论依据。

The carbon fiber reinforced polymer(CFRP) composites have been widely used in strengthening structures,especially the concrete filled-steel tube(CFT) structures because they have many advantages such as high strength,light quality,good energy absorption and easy construction.Based on the twin shear unified strength theory,the mechanical behavior of the square steel tube short columns filled with concrete and inner CFRP circular tube is analyzed.The effects of intermediate principal stress and the strength difference in tension and compression are considered in the unified strength theory and hence they can be applied to many kinds of materials under complex stress state.The restriction upon the core concrete by the inner CFRP circular tube,the strength reduction factor,the equivalent reduction factor,and the thickness side ratio effect are taken into account in the theoretical analysis.The load-carrying capacity formula of the square steel tube short columns filled with inner CFRP circular tube under axial compression is deduced.Parametric studied are carried out to evaluate the effects of intermediate principal stresses,CFRP deployment ratios and material strength parameters on the load-carrying capacity of the column.The formula is verified by a comparison between calculation results and experimental data.Results show that the inner CFRP circular tube can effectively restrain the core concrete.This new type of structural component makes full use of the advantages of CFRP,concrete and steel materials.The theoretical formula can provide theoretical basis for the structural optimization design of the concrete filled-steel tube.