EFFECTIVE LENGTHS IN BRACED STRUCTURES

The paper reviews the method for calculating effective length factors in braced frames currently presented in the Australian steel structures code, as 1250-1975. The method includes the stability function, gamma, that modifies the flexural stiffness of restraining members when they support large axial forces. It is shown that the stability function(a) implies a closed- form solution for the effective lengthfactors whereas stability solutions usually involve trial and error, (b) allows the effective length factors to vary with changing member sizes (all other parameters held constant) which is contrary to elastic buckling theory, and (C) does not account for the increased stability of fixed- ended restraining members. A revised stability function is presented, based on linear approximations and expressed in terms of effective length factors. A new set of design rules, incorporating a four- step trial and error procedure,is also presented. One of the numerical examples is reworked to illustrate the method and to show that it is consistent with elastic buckling theory. (Author/TRRL)

• Availability:
  • Find a library where document is available. Order URL: http://worldcat.org/issn/08190259
• Corporate Authors:

  Institution of Engineers

  11 National Circuit
  Barton, A.C.T.,   Australia 
• Authors:
  • Fraser, D J
• Publication Date: 1981-1

Media Info

• Features: Figures; References; Tables;
• Pagination: p. 80-88
• Serial:
  • Institution of Engineers (Australia) Civ Eng Trans
  • Volume: CE23
  • Issue Number: 1
  • Publisher: Institution of Engineers
  • ISSN: 0819-0259

Subject/Index Terms

• TRT Terms: Axial loads; Bracing; Buckling; Design; Elasticity (Mechanics); Force; Frames; Length; Stability (Mechanics); Standards; Steel; Steel structures
• Old TRIS Terms: Elastic theory
• ITRD Terms: 5522: Buckling; 9011: Design (overall design); 3322: Frame; 5930: Stability; 4542: Steel; 3605: Timbering
• Subject Areas: Bridges and other structures; Design; Highways; Materials; I24: Design of Bridges and Retaining Walls; I34: Steels and Metals;

Filing Info

• Accession Number: 00335749
• Record Type: Publication
• Source Agency: ARRB
• Files: ITRD, TRIS
• Created Date: Oct 28 1981 12:00AM