基于单根杆件承载力等效的假想荷载

Notional Load Consistent with Chinese Code for Design of Steel Structures GB 50017-2003

引入假想荷载与二阶弹性分析方法配合使用以简化框架柱稳定性设计,是钢框架设计的一种可选方法。假想荷载的确定原则是要与线性分析配合计算长度系数法决定的框架承载力相同,根据这个原则,本文采用单杆模型,研究了与我国规范配套的假想荷载,研究了影响参数,由于我国对强度计算和稳定性计算分开进行,会获得两组大小不同的假想荷载数据,取小的假想荷载。本文的结果表明,完全等效的假想荷载系数受到抗侧刚度系数的很大影响,几何长细比也稍有影响,材料屈服强度因子与目前规范建议的不同,与弯矩分布也有关系,截面不同,在不同平面内屈曲,假想荷载也有巨大差别,特别是工字形截面绕强轴和弱轴,假想荷载差值很大。通过数据整理,提出了精度很高的计算公式。

Notional load approach is a new option for design of steel structures established in the past decade. The notional load is determined under the requirement that the new approach predicts the same load carrying capacity as the traditional effective length approach. Based on this principle, this paper presents a simple study on the notional load used in consistent with the Chinese code for Design of Steel Structures. Because of independent check for strength and stability, two numerical values of notional load are achieved for each example. It is found that the exact notional load is strongly affected by lateral stiffness of column and is also slightly affected by the geometrical slenderness of column itself, the material yield strength factor is also different from the current code, and the variation of bending moment along member has also a strong effect. Type of cross sections and buckling plane has also great effect. Two formulas with excellent accuracy are presented in which all factors are included.