初始几何缺陷对非强支撑钢框架柱性能的影响

在钢框架二阶弹性分析中,结构整体初始几何缺陷和构件的初始几何缺陷是实际存在的,其影响不应忽略。基于由单根柱和梁组成的框架子结构模型,通过引入以上两种几何缺陷,得出了考虑初始几何缺陷影响的框架柱位移与内力的理论公式。利用该理论模型,可以较准确地分析框架结构整体几何缺陷与构件几何缺陷对二阶弹性弯矩的影响。参数分析结果表明:对于钢框架柱,结构的整体几何缺陷和构件几何缺陷对弯矩的影响均可以等效为作用于楼层处的假想水平力,而假想水平力的大小与作用于该楼层的竖向荷载有关。

INFLUENCE OF INITIAL GEOMETRIC IMPERFECTIONS ON BEHAVIOR OF PARTIALLY-BRACED STEEL FRAME COLUMNS

In second-order elastic analysis of the partially-braced steel frames, the initial geometric imperfections of overall frame as well as its individual member should not be neglected. So a practical second-order elastic model of a two-dimensional assemblage comprising a single column and a single beam to reflect the geometric imperfections is developed for the determination of the behavior of the steel frame columns. Using the practical model accounting for the influence parameters, the effects of the geometric imperfections can be accurately considered during the determination of the second-order elastic moments of the steel frame columns. Parametric studies are carried out to demonstrate the extent to which the involved parameters affect the behaviors of the partially-braced steel frame columns. The results of parametric analysis imply that the geometric imperfections of the partially-braced frame column may be replaced by the equivalent notional lateral load expressed as a fraction of the axial load acting on the floor.