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摘要
This paper presents the derivation of a new design formulation for the representation of the buckling strength of steel beam-columns, which follows the format and basic principles of novel and increasingly popular international design methods, such as the Direct Strength Method DSM (Schafer, 2008)- used predominantly in North America for the design of cold-formed steel members - and the General Method GM - included in the Eurocode EN 1993-1-1 (EN 1993-1-1, 2005) section 63.4 as an alternative way of designing generic steel members and structural systems. The paper focuses on the in-plane buckling strength of double-symmetric hot-rolled, tubular and welded sections, with compact sections; this focus on an otherwise well-understood problem allows for a clearer focus on the key aspects which need to be accounted for in a DSM/GM type representation of beam-column strength. In particular, a generalized definition of slenderness (in line with the DSM philosophy) and a generalized imperfection term, which accounts for the ratio between bending moments and axial forces in the beam column, are used to obtain an Ayrton-Perry (Ayrton and Perry, 1886; Rondal and Maquoi, 1979) type design formulation for beam column in-plane global buckling. In the paper, the key components that need addressing in a DSM - as well, as any other - beam-column design approach are highlighted, namely: i. the influence of the relative ratio between bending and compression loading, ii. the effect of non-uniform bending moment diagrams, fit the deterioration of the achievable plastic cross-sectional utilization due to loss of rigidity by yielding in slender members and iv. the interaction between buckling modes, in this case local and global buckling. The paper proposes a coherent, innovative design formulation which accounts for all of these effects and compares the outcome of the new strength predictions with numerical (non-linear FEM) and traditional Eurocbde results.
- 出版日期2016-10
