Wood - Lumber Stress Grade & Design

Credit: 2 PDH

Course Fee: $30.00

15 Pages


Course Summary

This course briefly discusses the U.S. Department of Commerce American Softwood Lumber Standard PS20 (1994) sorting criteria for two stress-grading methods, and the philosophy of how properties for engineering design are derived. The derived properties are then used in one of two design formats: (a) the load and resistance factor design (LRFD), which is based on a reference strength at the 5th percentile 5-min bending stress (AF&PA 1996), or (b) the allowable stress design (ASD), which is based on a design stress at the lower 5th percentile 10-year bending stress. The properties depend on the particular sorting criteria and on additional factors that are independent of the sorting criteria.

Learning Objectives

  • Responsibilities and Standards for Stress Grading
  • National Grading Rule
  • Visually Graded Structural Lumber
  • Visual Sorting Criteria
  • Procedures for Deriving Design Properties
  • Machine-Graded Structural Lumber
  • Machine Sorting Criteria
  • Procedures for Deriving Design Properties
  • Quality Control
  • Adjustment of Properties for Design Use
  • Shrinkage
  • Moisture Adjustments
  • Treatment Effects
  • Temperature Effects

Course Author

US Forest Service



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