Roof Loads for Reliability Analysis of Lumber Properties Data
Keywords:Roof loads, reliability, lumber, strength behavior, adjustment factors
With load information reported in previous studies, distributions of maximum lifetime roof loads are developed in a form suitable for use in reliability analyses of lumber properties data. A lognormal distribution is chosen as best representing normalized maximum lifetime roof snow load.
Examples are given in which contrasting lumber data sets are compared using the calculated load distributions and assuming that each set must provide equal reliability (equal safety) in the final design. A factor, k, resulting from this reliability analysis is shown to be a logical adjustment parameter for use in engineering design codes.
Allen, D. E. 1976. Limit states design—A probabilistic study. Can. J. Civil Eng.2(1):36-49.nAmerican National Standards Institute. 1982. Building code requirements for minimum design loads for buildings and other structures. ANSI Standard A58.1-82. U.S. Dep. Comm., Nat. Bur. Stand., Washington, DC.nAmerican Society for Testing and Materials. 1981a. Standard methods for establishing structural grades and related allowable properties for visually graded lumber. ASTM D 245-74. ASTM. Philadelphia, PA.nAmerican Society for Testing and Materials. 1981b. Standard methods for establishing clear wood strength values. ASTM D 2555-78. ASTM, Philadelphia, PA.nAmerican Society for Testing and Materials. 1981c. Standard method for evaluating allowable properties for grades of structural lumber. ASTM D 2915-74. ASTM, Philadelphia, PA.nBendtsen, B. A., and R. L. Youngs. 1981. Machine stress rating of wood: An overview. Proc. XVII IUFRO World Congress [Kyoto, Japan]. IUFRO, Vienna, Austria.nEllingwood, B. 1978. Reliability basis of load and resistance factors for reinforced concrete design. U.S. Dep. Comm., Nat. Bur. Stand., Washington, DC.nEllingwood, B. 1981. Reliability of wood structural elements. ASCE J. Struct. Div.107(ST1):73-87.nEllingwood, B., T. V. Galambos, J. G. MacGregor, and C. A. Cornell. 1980. Development of a probability based load criterion for American National Standard A58: Building code requirements for minimum design loads in buildings and other structures. National Bureau of Standards Special Publication 577. U.S. Dep. Comm., Nat. Bur. Stand., Washington, DC.nGalambos, T. V., and M. K. Ravindra. 1973. Tentative load and resistance factor design criterion for steel buildings. Structural Division Research Report No. 18. Washington Univ., St. Louis, MO.nGalligan, W. L., and D. W. Green. 1980. Development of standardized concepts for assignment and assessment of the mechanical properties of lumber: A continuing challenge for the 1980's. For. Prod. J.30(9):39-46.nGerhards, C. C., J. D. Barrett, B. Madsen, M. D. Strickler, and R. Pellerin. 1976. Proposed studies of time-related load effects on wood materials. For. Prod. J.26(12):39-40.nGoodman, J. R., M. D. Vanderbilt, M. E. Criswell, and J. Bodig. 1974. A rational analysis and design procedure for wood joist floor systems. Final report, National Science Foundation Grant GK-30853. Colo. State Univ., Fort Collins, CO.nGreen, D. W. 1980. Adjusting the static strength of lumber for changes in moisture content. In Proc. Symp. Workshop How the Environment Affects Lumber Design: Assessments and Recommendations. U.S. Dep. Agric, For. Serv., For. Prod. Lab., Madison, WI.nHahn, C. T., and S. S. Shapiro. 1967. Statistical methods in engineering. Vol. 1. Basic principles. John Wiley and Sons, Inc., New York, NY.nHoyle, R. J. 1978. Wood technology in the design of structures. Mountain Press Publ. Co., Missoula, MT.nHoyle, R. J., W. L. Galligan, and J. H. Haskell. 1979. Characterizing lumber properties for truss research. In Proc. Metal Plate Wood Truss Conference. For. Prod. Res. Soc., Madison, WI.nInternational Conference of Building Officials. 1973. Uniform Building Code, Vol. 1. ICBO, Whittier, CA.nLind, N. C, A. S. Nowak, and B. G. Moss. 1978. Risk analysis procedures II. Research Report. Dep. Civil Eng., Univ. of Waterloo, Waterloo, Ontario, Canada.nMadsen, B. 1978. In-grade testing—Problem analysis. For. Prod. J.28(4):42-50.nMadsen, B., W. Janzan, and J. Zwaazstra. 1980. Moisture effects in lumber. Dep. Civil Eng., Univ. of British Columbia, Vancouver, B.C., Canada.nMarin, L. A., and F. E. Woeste. 1981. Reverse proof loading as a means of quality control in lumber manufacturing. Trans. ASAE24(5):1273-1277, 1281.nNational Forest Products Association. 1978. Design values for wood construction. Supplement to the 1977 edition of the national design specification for wood construction. NFPA, Washington, DC.nPolensek, A. 1976. Finite element analysis of wood stud walls. ASCE J. Struct. Div.102(ST7):1317-1335.nSiu, W. W. C., S. R. Parimi, and N. C. Lind. 1975. Practical approach to code calibration. ASCE J. Struct. Div.101(ST7):1469-1480.nSuddarth, S. K., F. E. Woeste, and W. L. Galligan. 1978. Differential reliability: Probabilistic engineering applied to wood members in bending/tension. USDA For. Serv. Res. Pap. FPL 302. For. Prod. Lab., Madison, WI.nThurmond, M. B. 1982. The influence of load distribution on the reliability analysis of lumber properties data. Thesis submitted in partial fulfillment of the requirements for the degree of Master of Science. Virginia Polytechnic Inst. and State Univ., Blacksburg, VA.nTobiasson, W., and R. Redfield. 1980. Snow loads for the United States, Parts I and II. U.S. Army Cold Regions Research and Engineering Laboratory Report. U.S. Army CRREL, Hanover, NH.nU.S. Department of Commerce, National Bureau of Standards. 1981. NBS Voluntary Product Standard PS 20-70. U.S. Government Printing Office, Washington, DC.n
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