国家体育场扭曲箱形构件拉伸试验

为研究国家体育场钢结构扭曲箱形构件的抗拉性能,完成了2个1/4缩尺试件在单调拉伸荷载作用下的试验与参数影响计算分析,试件的变化参数为加劲肋间距。试验结果表明:试件的拉力-位移曲线呈双线性特征,试件受拉屈服发生在靠弯曲中心一侧的上翼缘与相邻腹板;受拉屈服荷载为1100kN;两个试件的弹性抗拉刚度分别为593kN/mm与614kN/mm;屈服后强化段抗拉刚度分别为39kN/mm与36kN/mm,分别为弹性抗拉刚度的6.6%与5.9%;卸载刚度均为930kN/mm,分别为弹性抗拉刚度的157%与151%。加劲肋间距从300mm减小到225mm,试件的抗拉刚度增加了5%,刚度提高有限。有限元计算结果与试验结果基本一致。

Tension tests of steel twisted box-section element of the National Stadium

In order to study the tensile behavior of steel twisted box-section elements of the National Stadium for the 2008 Beijing Olympic Games,two specimens with one-fourth scale were tested under monotonically increased tensile load. Finite element method(FEM) was applied to simulate the nonlinear behavior of the specimens as well.The variable considered was the space between intermediate diaphragms.Bilinear axial load-displacement curve was monitored for two specimens.Yielding of steel plate was concentrated at the top flange,closed to the center of the element curved axial line,and the webs connected to the yield flange.Tensile yield load of the two specimens was 1100kN.The axial tensile stiffness of the two specimens before yielding load was 593kN/mm and 614kN/mm,respectively.The corresponding value was 39kN/mm and 36kN/mm respectively after the specimen yielding and 930kN/mm during the unloading stage,which was 6.6% and 5.9%,157% and 151% of the elastic tensile stiffness of the specimen,respectively.Although the space between intermediate diaphragms was decreased from 300mm to 225mm,the tensile stiffness of the specimen increased 6% only.The FEM analysis results agreed well with the test results.