直接分析设计法中的受压构件等效初始缺陷研究

Research on equivalent initial imperfections of compression members in direct analysis design method

在GB 50017—2017《钢结构设计标准》中,仅对考虑材料弹性阶段的直接分析设计法中的构件初始缺陷取值作出了规定,对考虑材料弹塑性发展的直接分析设计法中未给出构件初始缺陷取值的具体数值。为此,基于钢结构塑性稳定理论,利用轴心受压构件稳定系数反向推导其等效初始缺陷,包括初始几何缺陷和残余应力。根据不同的截面类型和钢材牌号,给出受压构件不同的等效初始缺陷,使直接分析设计方法能够真正地应用于实际工程中。利用直接分析设计软件NIDA,建立带有初始缺陷的弯曲单元,模拟受压构件的等效初始缺陷,得到构件的稳定承载力系数,并与轴压构件稳定系数φ进行对比分析,验证了构件等效初始缺陷取值的正确性。

The GB 50017—2017 ‘Standard for design of steel structures’ newly promulgated only stipulates the initial imperfections of members in direct analysis design method considering material elasticity stage, but does not give specific values for the initial imperfections of members in direct analysis design method considering material elastic-plastic development stage. Based on the plastic stability theory of steel structure, the equivalent initial imperfections, including initial geometric imperfections and residual stresses, were deduced by using the stability coefficient of axial compression. According to different section types and steel grades, different equivalent initial imperfections of compression members were given, so that the direct analysis design method can be truly applied to practical engineering. A bending element with initial imperfections was established by using NIDA software, and the equivalent initial imperfections were simulated. The stability bearing capacity coefficient of the members was obtained, which was compared with the stability coefficient φ of axial compression members to verify the validity of the equivalent initial imperfections of the members.