设对拉片方形薄壁钢管混凝土短柱的试验研究与有限元分析

为改善薄壁钢管混凝土柱的力学性能,提出了内部设置横向对拉片的薄壁钢管混凝土柱的新型结构形式。通过对无对拉片、单向和双向设置对拉片3种截面形式、2种对拉片纵向设置间距为100mm和200mm的15个薄壁钢管混凝土轴压短柱的试验研究,比较和分析了构件的试验现象、破坏形式、荷载-位移曲线等。结果显示:设对拉片的薄壁钢管混凝土短柱以剪切破坏模式为主,对拉片与混凝土的粘结在短柱压溃之前均能保持共同工作;设置间距为100mm时,对拉片能有效改善薄壁钢管混凝土短柱的工作性能,与无对拉片试件相比,设置单向对拉片短柱的极限承载力提高了22.5%,设置双向对拉片的提高了27.4%;设置间距为200mm时,对拉片对短柱的极限承载力提高的作用不大。因此对拉片的间距是影响试件承载力的主要因素,间距越密承载力越高。采用有限元程序ABAQUS 6.4对试件进行了分析,计算与试验结果吻合较好;通过研究各试件柱中截面混凝土的纵向应力分布情况,阐述了设对拉片短柱的受力机理。

Experimental study and finite element analysis of square stub columns with tensile sheets of concrete-filled thin-walled steel tube

New type of CFTST columns with cold-formed longitudinal straight ribs is suggested to improve the capability of concrete-filled thin-walled steel tubular(CFTST) columns.Fifteen square stub columns of CFTST with or without transverse tensile sheets(unidirectional or bidirectional) inside of the steel tube are tested under axial compression loading,and the tensile sheets in columns are arranged in two longitudinal interval which are 100mm and 200mm.The experimental phenomena,damage modes and load-deformation relationship are analyzed.The test results show that the tensile sheets cohere with concrete very well until the specimens are damaged,and the damage modes are mainly of shear forms.The ultimate capabilities of specimens with tensile sheets longitudinal interval 100mm of CFTST which increases more than 22.5%(unidirectional) or 27.4%(bidirectional) respectively compared with the specimens without tensile sheets,but the ultimate capabilities of specimens with tensile sheets longitudinal interval 200mm are not improved,so the most significant factor which influences the ultimate capabilities of specimens is the interval between tensile sheets,i.e.the smaller the interval is,the higher the ultimate capability.The element analysis by ABAQUS 6.4 program is conducted,and the test results are closely predicted,the longitudinal concrete stress distribution of mid-column and the stressed mechanics of stub columns with tensile sheets are also investigated.