Structural Engineering and Mechanics

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Stability of unbraced frames under non-proportional loading

  • Xu, L. (Department of Civil Engineering, University of Waterloo) ;
  • Liu, Y. (Department of Civil Engineering, University of Waterloo) ;
  • Chen, J. (Department of Civil Engineering, University of Waterloo)
  • Published : 2001.01.25
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Abstract

This paper discusses the elastic stability of unbraced frames under non-proportional loading based on the concept of storey-based buckling. Unlike the case of proportional loading, in which the load pattern is predefined, load patterns for non-proportional loading are unknown, and there may be various load patterns that will correspond to different critical buckling loads of the frame. The problem of determining elastic critical loads of unbraced frames under non-proportional loading is expressed as the minimization and maximization problem with subject to stability constraints and is solved by a linear programming method. The minimum and maximum loads represent the lower and upper bounds of critical loads for unbraced frames and provide realistic estimation of stability capacities of the frame under extreme load cases. The proposed approach of evaluating the stability of unbraced frames under non-proportional loading has taken into account the variability of magnitudes and patterns of loads, therefore, it is recommended for the design practice.

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References

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  3. Effective buckling length of steel column members based on elastic/inelastic system buckling analyses vol.26, pp.6, 2007, https://doi.org/10.12989/sem.2007.26.6.651
  4. Stability of multi-storey unbraced steel frames subjected to variable loading vol.63, pp.11, 2007, https://doi.org/10.1016/j.jcsr.2007.01.010
  5. Story stability of semi-braced steel frames vol.58, pp.4, 2002, https://doi.org/10.1016/S0143-974X(01)00063-3
  6. System buckling analysis for multi-story frames subjected to nonconservative forces vol.15, pp.2, 2015, https://doi.org/10.1007/s13296-015-6003-8
  7. Buckling of restrained steel columns due to fire conditions vol.8, pp.2, 2001, https://doi.org/10.12989/scs.2008.8.2.159