Practice in WOOD PROPERTIES AND LUMBER GRADES – due beginning of class October 26
For this assignment, you will need to reference sections and tables in the National Design Specification (NDS) for Wood Construction provided in this supplemental file. Note that you can view the entire NDS 2015 Supplement here.
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1. Read chapter 4.11 (Sizes of Structural Lumber) and study table 1A in the NDS. Then, determine the dressed size and section modulus (for both weak and strong axes) for the following members.
a) 2×4; b) 8×8; c) 4×10; d) 6×16
2. Read chapter 4.3 (Methods of Grading Structural Lumber). Then, in your own words, describe what is meant by the terms “visually graded sawn lumber” and “machine stress-rated (MSR) lumber.” Write a paragraph with 3 or 4 informative sentences for each term.
3. Give the reference design values for the material properties Fb, Ft, Fv, Fc(perp), Fc, and E for No.1 Eastern White Pine for the following sizes:
a. 10×10 b. 12×14 c. 4×16, d. 4×4, e. 2×10, f. 6×12, g. 6×8, h. 10×14
4. Read example 4.15 (pg. 217) in the textbook. Then, determine the adjusted design values in Allowable Stress Design (ASD) for the following members and loading conditions. All members are No. 2 Hem-Fir and are fully braced to prevent lateral-torsional buckling. Bending occurs about the strong axis.
a. Roof joists are 2×10 at 16 in o.c. which directly support the roof sheathing. Loads are (D+S).
b. A 6×14 carries an equipment load that can be considered a permanent load.
c. Purlins in a roof are 4×14 at 8ft o.c. Loads are (D+Lr)
d. Floor beams are 4×6 at 4ft. o.c. Loads are (D+L). High-humidity conditions exist, and the moisture content may exceed 19 percent.