钢框架柱平面内整体稳定验算的两种方法对比

摘要

先建立两个有初始几何缺陷的多层钢框架结构,通过有限元分析分别得到这两个框架的竖向极限荷载Pcr和水平极限荷载Hcr；再对与这两个框架几何及截面相同但没有初始缺陷的框架,用之前计算得到的竖向和水平极限荷载分别按一阶弹性分析和二阶弹性分析得到其内力,用我国现行GB50017 - 2003《钢结构设计规范》中压弯杆件极限承载力验算公式计算其名义应力,并与实际结果比较.结果证明,进行钢框架压弯杆件平面内稳定验算时,对框架采用二阶弹性分析,并将柱的计算长度取为实际柱长,所得验算结果较对框架采用一阶弹性分析并将柱的计算长度取为框架弹性屈曲长度合理.但总体来说,两种方法的验算结果都均偏于保守.%First, two 8teel frames with geometric imperfections are built,the ultimate load of these frames Pa and Ha under horizontal and vertical load are got through finite element analysis. Then use the ultimate load Pa and Ha to calculate the internal force of the same two frames without geometric imperfections through the way of first-order analysis and second order analysis. Then get the nominal stress of the column using the formula of the ultimate load capacity of bending-compression members in steel structure design code in current use in our country( GB5OO17 -2003), and compare it with the real stress. It proves that when using the formula of the ultimate load capacity of bending-compression members to check the stability of columns, using the second order elastic analysis to calculate the internal force of the frame and choosing the real length to be the effective length of the column, the result is better and safer than that through the way of using the first order elastic analysis to calculate the internal force of the frame and choosing the elastic buckling length to be the effective length of the column.