Abstract
Abstract Stability checking is an essential element of the dimensioning of steel frame structures. One of the stability checking methods allowed by EN 1993-1-1 is the so-called general method of assessing structural stability, based on buckling curves and relative structure slenderness λ ¯ op {\bar \lambda _{op}} usually determined through numerical analyses. But this method is not widely used because of the limited computing capabilities of the engineering programs dedicated to static load analyses and difficulties in interpreting the results of the computations. The commonly used computer programs enable one to determine the shape of buckling and critical load amplifier αcr , from which one cannot directly determine the risk of buckling of a real structure. This paper presents a modified and innovative approach to the general method of assessing structural stability, which uses only three parameters, that is, the type of cross section, cross-section strength utilisation and αcr , to determine a member’s/structure’s bearing capacity mobilisation from the stability condition. The problem solution is presented in the form of simple formulas and legible diagrams. Finally, synthetic conclusions are formulated.
Highlights
In order to evaluate the ultimate limit state (ULS) of steel members in compression or/and bending, it is necessary to determine their buckling resistance (Boissonnade et al, 2006; Sedlacek & Naumes, 2009; Davison & Owens, 2012; Stachura & Giżejowski, 2015; Hajdu & Papp, 2018)
The analyses conducted allowed for the formulation of the following conclusions regarding the proposed modified method of assessing the ultimate load-bearing capacity of a structural member from the stability loss condition: 1) This method can be applied to arbitrarily supported members being in compression and bending relative to the axis of greater stiffness, for any load distribution
5) In the case of compression-only elements, the proposed nomographs (Figs 1–6) provide the same results of the assessment of the ultimate load-bearing capacity of the elements as the classical approach presented in sect. 6.3.1 (EN 1993-1-1:2005)
Summary
In order to evaluate the ultimate limit state (ULS) of steel members in compression or/and bending, it is necessary to determine their buckling resistance (Boissonnade et al, 2006; Sedlacek & Naumes, 2009; Davison & Owens, 2012; Stachura & Giżejowski, 2015; Hajdu & Papp, 2018). 6.3.1-6.3.3 [EN 1993-1-1:2005]) 2) The general method of evaluating stability, using buckling curves and global relative structural slenderness op determined on the basis of the critical load amplifiers for system elastic buckling The amplifiers are usually determined through a numerical analysis 3) A geometrically non-linear elastic analysis (GNA) of a structure with initial bow imperfections of bars and sway imperfections of frames, which can be replaced with equivalent forces Methods 3 and 4 are rarely used because of the required long computing time, the difficult choice of proper imperfections for a large number of bars and load combinations and the fact that they have not been widely implemented in engineering computer programs. Method 2 is not commonly used due to insufficient knowledge as to its proper use, difficulties in interpreting its results and the lack of software that would enable a comprehensive analysis of structures in different computing systems. The Hungarian ConSteel software seems to be the most advanced in this matter
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