不同轴压模式下开孔板加劲型方钢管混凝土力学性能试验

Experimental Research on the Behavior of Concrete-filled SHS Steel Tube with PBL under Different Loading Conditions

为研究工程中构件可能出现的各种受压状态,文中进行了不同加载模式下开孔板加劲型方钢管混凝土轴压试验。加载模式分别为钢管和混凝土截面同时受力、钢管存在初应力即钢管截面先受力后同时受力、仅钢管截面受力和仅核心混凝土截面受力。设计了8组16个试件,分别从破坏现象、轴压承载力、轴压刚度、应变分布及套箍效应等方面分析各试件的力学性能。试验结果表明:开孔板加劲肋能提高钢管与混凝土之间的连接力,仅核心混凝土或仅钢管截面受力时,能减小钢管或混凝土独立承担荷载的长度,有效将荷载传递至组合截面,从而提高构件的承载力,改变构件的轴压刚度和破坏模式;钢管和混凝土截面共同受力、仅核心混凝土受力和钢管存在初应力3种加载模式下开孔板加劲型方钢管混凝土短柱的承载力接近,均高于钢管和混凝土二者承载力的简单叠加,构件的横向应变呈“双波”曲线;仅钢管截面受力时构件承载力显著小于以上3种加载模式,但远高于空钢管构件的承载力,构件的横向应变呈“单波”曲线。

In order to study the various compressive states of the components in projects,the axial compression tests of reinforced square steel tube concrete with perforated plates under different loading modes are carried out.The loading modes are simultaneous stress of steel pipe and concrete cross-section,initial stress of steel pipe,that is,steel pipe cross-section is stressed first and then simultaneously,only steel pipe cross-section and core concrete cross-section.Eight groups of 16specimens are designed,and the mechanical properties of each specimen are analyzed from the aspects of failure phenomena,axial compression bearing capacity,axial compression stiffness,strain distribution and stirrup effect.The test results show that the stiffener of the perforated plate can improve the connection force between the steel pipe and the concrete.When only the core concrete or only the steel pipe section is stressed,the length of the steel pipe or concrete independently bearing the load can be reduced,and the load can be effectively transferred to the combined section so as to improve the bearing capacity of the member and change the axial compression stiffness and failure mode of the member;the bearing capacity of the columns is close under the 3loading modes of both the steel pipe and concrete cross section being stressed,only the core concrete in stress and the initial stressing of the steel pipe,all is higher than the simple superposition of the bearing capacity of both steel pipes and concrete.The lateral strain of the members presents a“double wave”curve;when the steel pipe section is stressed,the bearing capacity of the members is significantly less than the above three loading modes,but far higher than the bearing capacity of hollow steel tube members,the lateral strain of the members presents a“single wave”curve.