Floor Loads for Reliability Analysis of Lumber Properties Data


  • Michael B. Thurmond
  • Frank E. Woeste
  • David W. Green


Floor loads, roof loads, reliability, lumber, strength, adjustment factors


Utilizing load information reported in previous studies, we have developed distributions of maximum lifetime floor live loads in a form suitable for use in reliability analyses of lumber properties data. An extreme value type I distribution is chosen as best representing normalized maximum lifetime floor live loads.

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, or equal safety, in the final design. A factor, k, resulting from the reliability analysis is shown to be a logical adjustment parameter for use in engineering design codes.

Combining these results with those of an earlier paper, the selection of load distributions for use in reliability analysis of lumber properties data is discussed.


Allen, D. E. 1976. Limit states design—A probabilistic study. Can. J. Civil Eng. 2(1):36-49.nAmerican National Standards Institute. 1982. Proposed ANSI Standard A58.1-81: Building code requirements for minimum design loads for buildings and other structures. U.S. Dept. Commerce, Nat. Bur. Stand., Washington, DC.nAmerican Society for Testing and Materials. 1983. Standard methods for establishing structural grades and related allocable properties for visually graded lumber. ASTM Stand. Desig. D245-81. ASTM, Philadelphia, PA.nChalk, P. L., and R. B. Corotis. 1980. A probability model for design live loads. ASCE J. Struct. Div. 106(ST9):2017-2033.nCorotis, R. B., and V. A. Doshi. 1977. Probability models for live-load survey results. ASCE J. Struct. Div. 103(ST6):1257-1274.nEllingwood, B. 1978. Reliability basis of load and resistance factors for reinforced concrete design. U.S. Dept. Commerce, Nat. Bur. Stand., Washington, DC.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. Nat. Bur. Stand. Special Pub. 577. U.S. Dept. Commerce, Nat. Bur. Stand., Washington, DC.nGalambos, T. V., and M. K. Ravindra. 1973. Tentative load and resistance factor design criterion for steel buildings. Struct. Div. Res. Rep. No. 18. Washington Univ., St. Louis, MO.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. USDA For. Serv., For. Prod. Lab., Madison, WI.nHahn, G. J., and S. S. Shapiro. 1967. Statistical models in engineering. John Wiley and Sons, Inc. New York.nHoyle, R. J. 1978. Wood technology in the design of structures. Mountain Press Publishing 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 Conf. For. Prod. Res. Soc., Madison, WI.nJohnson, A. I. 1953. Strength, safety and economical dimensions of structures. Bull. No. 12. Royal Inst. Technol., Div. Building Statistics and Struct. Eng., Stockholm, Sweden.nJoint Committee on Structural Safety. 1976. Superimposed loadings in dwellings. Basic Notes on Actions, third draft, A-02. Laboratories Nacional de Engenharia Civil, Lisbon, Portugal.nKarmen, T. 1969. Statistical investigations on live loads on floors. Report of Committee W23 on Basic Structural Engineering Requirements for Buildings. Internat. Counc. Building Res. Studies and Documentation, Madrid, Spain.nMarin, L. A., and F. E. Woeste. 1981. Reverse proof loading as a means of quality control in lumber manufacturing. Trans. ASAE 24(5):1273-1277, 1281.nNational Forest Products Association. 1982. Design values for wood construction. Supplement to the 1982 edition of the National Design Specification for wood construction. NFPA, Washington, DC.nOtt, L. 1977. An introduction to statistical methods and data analysis. Duxbury Press, North Scituate, MA.nPaloheimo, E., and M. Ollila. 1973. Research in live loads of persons. Ministry of Domestic Affairs, Helsinki, Finland.nPier, J. C., and C. A. Cornell. 1973. Spatial and temporal variability of live loads. ASCE J. Struct. Div. 102(ST3):591-607.nSentler, L. 1974. A live load survey in domestic houses. Report 47. Lund Inst. Technol., Div. Building Technol., Lund, Sweden.nSentler, L. 1975. A stochastic model for live loads on floors in buildings. Report 60. Lund Inst. Technol., Div. Building Technol., Lund, Sweden.nSentler, L. 1976. Live load surveys, a review with discussions. Report 78. Lund Inst. Technol., Div. Building Technol., Lund, Sweden.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 of Master of Science, Virginia Polytechnic Inst. and State Univ., Blacksburg, VA.nThurmond, M. B., F. E. Woeste, and D. W. Green. 1984. Roof loads for reliability analysis of lumber properties data. Wood Fiber Sci. 16(2):278-296.nWen, Y. K. 1977. Statistical combination of extreme loads. ASCE J. Struct. Div. 103(ST5):1079-1093.nZahn, J. J. 1977. Reliability-based design procedures for wood structures. For. Prod. J. 27(3):21-28.n






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