Practical second-order analysis and design of single angle trusses by an equivalent imperfection approach

S. H. Cho, Siu Lai Chan

Research output: Journal article publicationJournal articleAcademic researchpeer-review

4 Citations (Scopus)


Steel angles are widely used in roof trusses as web and chord members and in lattice towers. Very often angle members are connected eccentrically. As a result, not only an angle member is under an axial force, but it is also subject to a pair of end eccentric moments. Moreover, the connection at each end provides some fixity so neither pinned nor the fixed end represents the reality. Many national design codes allow for the effects due to eccentricities by modifying the slenderness ratio and reducing the compressive strength of the member. However, in practice, it is difficult to determine accurately the effective length. The concept behind this method is inconsistent with strength design of members of other cross-sectional types such as I or box sections of which the buckling strength is controlled by the Perry constant or the initial imperfection parameters. This paper proposes a method for design of angle frames and trusses by the second-order analysis. The equivalent initial imperfection-to-length ratios for equal and unequal angles to compensate the negligence of initial curvatures, load eccentricities and residual stresses are determined in this paper. From the obtained results, the values of imperfection-to-length ratios are suggested for design and analysis of angle steel trusses allowing for member buckling strength based on the Perry-Robertson formula.
Original languageEnglish
Pages (from-to)443-458
Number of pages16
JournalSteel and Composite Structures
Issue number6
Publication statusPublished - 1 Jan 2005


  • Angles
  • Buckling
  • Eccentricities
  • Initial imperfections

ASJC Scopus subject areas

  • Civil and Structural Engineering
  • Building and Construction
  • Metals and Alloys


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