Structural Engineering and Mechanics

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Minimum stiffness of bracing for multi-column framed structures

  • Aristizabal-Ochoa, J. Dario (National University, School of Mines)
  • Published : 1998.04.25
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Abstract

A method that determines the minimum stiffness of baracing to achieve non-sway buckling conditions at a given story level of a multi-column elastic frame is proposed. Condensed equations that evaluate the required minimum stiffness of the lateral and torsional bracing are derived using the classical stability functions. The proposed method is applicable to elastic framed structures with rigid, semirigid, and simple connections. It is shown that the minimum stiffness of the bracing required by a multi-column system depends on: 1) the plan layout of the columns; 2) the variation in height and cross sectional properties among the columns; 3) the applied axial load pattern on the columns; 4) the lack of symmetry in the loading pattern, column layout, column sizes and heights that cause torsion-sway and its effects on the flexural bucking capacity; and 5) the flexural and torsional end restrains of the columns. The proposed method is limited to elastic framed structures with columns of doubly symmetrical cross section with their principal axes parallel to the global axes. However, it can be applied to inelastic structures when the nonlinear behavior is concentrated at the end connections. The effects of axial deformations in beams and columns are neglected. Three examples are presented in detail to show the effectiveness of the proposed method.

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References

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  2. Discussion of “Buckling and Second-Order Effects in Dual Shear-Flexural Systems” by Tong Gengshu, Yong-Lin Pi, Mark Andrew Bradford, and Francis Tin-Loi vol.137, pp.2, 2011, https://doi.org/10.1061/(ASCE)ST.1943-541X.0000046
  3. Buckling of Flexural-Shear Bracing System and Its Braced Steel Frames vol.18, pp.11, 2015, https://doi.org/10.1260/1369-4332.18.11.1831
  4. Classic Buckling of Three-Dimensional Multicolumn Systems under Gravity Loads vol.128, pp.6, 2002, https://doi.org/10.1061/(ASCE)0733-9399(2002)128:6(613)
  5. Stability of columns with semi-rigid connections including shear effects using Engesser, Haringx and Euler approaches vol.33, pp.3, 2011, https://doi.org/10.1016/j.engstruct.2010.12.008