设置斜肋方形薄壁钢管混凝土轴压短柱研究

为改善薄壁钢管混凝土柱力学性能,提出设置斜肋方形薄壁钢管混凝土柱的结构形式.根据无肋、单向设置斜肋和双向设置斜肋3种截面形式、2种截面尺寸的18个薄壁钢管混凝土轴压短柱试验结果,比较和分析了各试件的试验现象、破坏模式及荷载位移曲线等.结果表明:薄壁钢管混凝土短柱以剪切破坏模式为主;肋与混凝土在试件破坏之前,均能保持良好粘结.设肋的短柱能达到较高的极限承载力,与无肋的试件相比,单向设置斜肋短柱的极限承载力提高了18%,双向设置斜肋的提高了29%.采用大型有限元程序ABAQUS6.4对每个试件的试验全过程进行了模拟计算,计算结果与试验结果吻合较好.通过数值计算,研究了截面尺寸相同的素混凝土短柱及无肋、单向、双向设置斜肋薄壁钢管混凝土轴压短柱的柱中截面混凝土纵向应力的分布规律,为进一步开展设肋短柱研究工作提供了依据.

Research on square stub columns with oblique ribs of concrete-filled thin-walled steel tube under axial compression loading

In order to improve the mechanical capability of columns of concrete-filled thin-walled steel tube(CFTST),eighteen square stub columns of CFTST with or without longitudinal oblique ribs inside of the steel tube were tested under axial compression loading.There are two different constitution forms for the square tubes with ribs in the test specimens,one consists of two welded channels with stiffening lips(channel tubes),another is made of four welded equal-leg angles with stiffening lips(angle tubes).The test results show that the ribs(lips) cohere with concrete very well before the specimens are damaged,and the damage modes are mainly of shear forms.The ultimate capabilities of the stub column specimens made of channel or angle tubes can increase more than 18% or 29% respectively comparing with the specimens without ribs.The element analysis by ABAQUS6.4 program was conducted,and the test and analysis results are very close to each other.The longitudinal stress distribution along the concrete section in the mid of column for every specimens is also calculated,which is useful for further investigation.