Duration of Load Effects in LRFD for Wood Construction
Publication: Journal of Structural Engineering
Volume 117, Issue 2
Abstract
The wood industry is developing a load and resistance factor design (LRFD) specification for wood construction. This effort provides an opportunity to reevaluate and restructure the current bases for design with wood, and to develop a specification using concepts of probability‐based limit‐states design. Wood design must take into account the fact that wood is a natural material with large variations in mechanical properties, sensitive to the rate of application and duration of structural loads. These complications are addressed by modeling structural loads as random processes, rather than as random variables, and by postulating limit states that reflect the possibility of failure by either progressive damage accumulation or overload. Current treatment of duration of load effects in the national design specification is found to be inconsistent from a uniform reliability viewpoint. Practical LRFD criteria that are consistent with a desired reliability measure can be developed to reflect the time‐dependent nature of wood behavior.
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References
1.
American national standard minimum design loads for buildings and other structures. (1982). ANSI A58.1, American National Standards Institute, New York, N.Y.
2.
Barrett, J. D., and Foschi, R. O. (1978). “Duration of load and probability of failure in wood, parts I and II.” Can. J. Civ. Engrg., 5(4), 505–532.
3.
Chalk, P., and Corotis, R. (1980). “A probabilistic model for design live loads.” J. Struct. Div., ASCE, 106(10), 2017–2030.
4.
Ellingwood, B. (1981). “Reliability of wood structural elements.” J. Struct. Div., ASCE, 107(1), 73–87.
5.
Ellingwood, B., McGregor, J. G., Galambos, T. V., and Cornell, C. A. (1982). “Probability based load criteria: Load factors and load combinations.” J. Struct. Div., 108(5), 978–997.
6.
Ellingwood, B., and Redfield, R. K. (1983). “Ground snow loads for structural design.” J. Struct. Engrg., ASCE, 109(4), 950–964.
7.
Ellingwood, B., Hendrickson, E., and Murphy, J. F. (1988). “Load duration and probability based design of wood structural members.” Wood and Fiber Sci., 20(2), 250–265.
8.
Foschi, R. (1984). “Reliability of wood structural systems.” J. Struct. Engrg., ASCE, 110(12), 2995–3013.
9.
Foschi, R. O., Folz, B. R., and Yao, F. Z. (1989). “Reliability based design of wood structures.” Structural Research Series Report No. 34, Univ. of British Columbia, Vancouver, British Columbia, Canada.
10.
Galambos, T. V., Ellingwood, B. R., McGregor, J. G., and Cornell, C. A. (1982). “Probability based load criteria: Assessment of current design practice.” J. Struct. Div., ASCE, 108(5), 959–976.
11.
Gerhards, C., and Link, C. (1986). “Effect of loading rate on bending strength of Douglas‐fir 2 by 4's.” Forest Products J., 36(2), 63–66.
12.
Hendrickson, E., Ellingwood, B., and Murphy, J. F. (1987). “Limit state probabilities of wood structural members.” J. Struct. Engrg., ASCE, 113(1), 88–106.
13.
Hsiao, L.‐E., Yu, W.‐W., and Galambos, T. V. (1990). “AISI LRFD method for cold‐formed steel structural members.” J. Struct. Engrg., ASCE, 116(2), 500–517.
14.
Knab, L. I., and Moody, R. (1978). “Glulam design criteria for temporary structures.” J. Struct. Div., ASCE, 104(9), 1485–1494.
15.
Load and resistance factor design specification for steel buildings. (1986). American Institute of Steel Construction, Chicago, Ill.
16.
“Load and resistance factor design for engineered wood construction—A prestandard report.” J. F. Murphy, ed., ASCE, New York, N.Y.
17.
Madsen, B. (1975). “Strength values for wood and limit states design.” Can. J. Civ. Engrg., 2(3), 270–279.
18.
'National Design Specification for Wood Construction.” (1986). National Forest Product Association, Washington, D.C.
19.
O'Rourke, M. P., Redfield, R., and von Bradsky, P. (1982). “Uniform snow loads on structures.” J. Struct. Div., ASCE, 108(12), 2781–2798.
20.
Peterson, J. (1978). “Tensile strength of L3 Douglas‐fir glulam members.” J. Struct. Div., ASCE, 104(1), 1–8.
21.
“Reliability based design.” (1984). Structural wood research: State of the art and research needs. R. Itani and K. Faherty, eds., ASCE, New York, N.Y.
22.
Sexsmith, R. G., and Fox, S. (1978). “Limit states design concepts for timber engineering.” Forest Prod. J., 28(5), 49–54.
23.
Wood, L. W. (1951). “Relation of strength of wood to duration of load.” Report R1916, Forest Products Laboratory, Madison, Wis.
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Copyright © 1991 ASCE.
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Published online: Feb 1, 1991
Published in print: Feb 1991
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