钢管混凝土多排多列内栓钉受剪性能

SHEAR PERFORMANCE OF MULTI-STUDS BETWEEN STEEL TUBE AND CORE CONCRETE

  • 摘要: 进行了钢管混凝土多排多列内栓钉(群钉)试件的推出试验,其中6个带栓钉,1个不带栓钉,试件参数为栓钉环向布置间距、纵向布置间距和排数。采用ABAQUS软件建立了三维有限元模型,对试验结果进行了计算分析,计算结果与试验结果吻合较好。试验与分析结果表明:钢管混凝土群钉推出试件受力全过程由弹性段、弹塑性段、下降段和荷载残余段组成;沿加载方向,紧邻栓钉背部的混凝土应力为50.1 MPa~68.8 MPa,超过混凝土圆柱体抗压强度(ƒc'=50.1 MPa),混凝土发生较大塑性变形;栓钉根部Mises应力最大,最先达到材料的极限强度,并发生剪断破坏;单根栓钉平均抗剪承载力随着群钉环向和纵向间距的减小以及排数的增加而降低,提出了这三个因素对单根栓钉平均抗剪承载力的折减系数计算公式。为充分利用栓钉抗剪性能,避免混凝土先于栓钉破坏,建议设计中栓钉环向和纵向间距应分别不小于3.4倍和4.4倍栓钉直径。分析表明,环向间距、纵向间距和排数三个因素对栓钉抗剪承载力的影响彼此独立,它们对群钉抗剪承载力的影响可采用三个折减系数相乘的计算方法。

     

    Abstract: Concrete-filled steel tubular (CFST) specimens with multi-row and multi-column studs were designed for push-out tests, including 6 specimens with studs and 1 specimen without studs. Key experimental parameters involved the circular space, the longitudinal space and the amount of rows of studs. In the meantime, the finite element analysis software, ABAQUS, was used to simulate the CFST push-out test. The numerical results coincide well with the experimental results. The test results and numerical analysis show that the load-slip curve of the specimen with multi-studs consists of linear elastic stage, elastic-plastic stage, load descent stage and load residual stage. Along the loading direction, the concrete stress at the back of the stud is 50.1 MPa~68.8 MPa, exceeding the cylinder compressive strength ( ƒc'= 50.1 MPa), so that the concrete deforms greatly. Mises stress in root is the largest in all studs. The root part reaches the ultimate strength first and then cut off. The average shear bearing capacity of one stud decreases with the decrease in the circular space, longitudinal space and the increase of rows. The computational formulas of three reduction coefficients are proposed. To make full use of the shear performance and avoid concrete crack before stud, the circular and longitudinal spaces should not be less than 3.4 and 4.4 times the stud diameter, respectively. The analysis results indicate that the three factors: the circular space, longitudinal space and the amount of rows are mutually independent. The shear bearing capacity reduction factor can be expressed as the multiplication of the three reduction coefficients.

     

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