Counteracting Structural Loads: Treatment in ASCE Standard 7-05
Publication: Journal of Structural Engineering
Volume 135, Issue 1
Abstract
The load combinations in ASCE Standard 7 for load and resistance factor design (LRFD) and for allowable stress design (ASD) differ in their treatment of counteracting loads, where the permanent gravity load (dead load) stabilizes the structural system against the effect of uplift or lateral loads. In LRFD, the loads are factored prior to the analysis, and the load factor on dead load is less than unity. In ASD, one factor of safety (the allowable stress factor) had been applied to the difference between the nominal load effects through the 1995 edition of ASCE Standard 7. Beginning with the 1998 edition, the load factor on nominal dead load in the ASD combination was increased to 0.6 to achieve consistency between ASD and LRFD. This particular ASD load requirement has been controversial and has drawn criticism from certain segments of the structural engineering community. This technical note examines the treatment of counteracting loads in ASCE Standard 7 from a reliability viewpoint, and shows that failure to reduce the gravity load for design may lead to inadequate safety.
Get full access to this article
View all available purchase options and get full access to this article.
References
American Institute of Steel Construction (AISC). (2005). Specification for structural steel buildings, AISC, Chicago.
Allen, D. E. (1969). “Safety factors for stress reversal.” Int. Assoc. Bridge Struct. Eng., 29(11), 19–27.
ASCE. (2005). “Minimum design loads for buildings and other structures.” ASCE Standard 7-05, ASCE, Reston, Va.
Ellingwood, B., and Tekie, P. B. (1999). “Wind load statistics for probability-based structural design.” J. Struct. Eng., 125(4), 453–464.
Ellingwood, B., MacGregor, J. G., Galambos, T. V., and Cornell, C. A. (1982). “Probability-based load criteria: Load factors and load combinations.” ASCE J. Struct. Div., 108(5), 978–997.
Galambos, T. V., Ellingwood, B., MacGregor, J. G., and Cornell, C. A. (1982). “Probability-based load criteria: Assessment of current design practice.” ASCE J. Struct. Div., 108(5), 959–977.
Sparks, P. R., Schiff, S. D., and Reinhold, T. A. (1994). “Wind damage to envelopes of houses and consequent insurance losses.” J. Wind. Eng. Ind. Aerodyn., 53, 145–155.
Information & Authors
Information
Published In
Journal of Structural Engineering
Volume 135 • Issue 1 • January 2009
Pages: 94 - 97
Copyright
© 2009 ASCE.
History
Received: Apr 2, 2007
Accepted: Jun 20, 2008
Published online: Jan 1, 2009
Published in print: Jan 2009
Notes
Note. Associate Editor: Venkatesh Kumar R. Kodur
Authors
Metrics & Citations
Metrics
Citations
Download citation
If you have the appropriate software installed, you can download article citation data to the citation manager of your choice. Simply select your manager software from the list below and click Download.