Problem 1
Answer the following questions, given a simply-supported, single-span sawn lumber beam on a flat roof, using the following information and ASD design procedures:
Critical Load Combination: D + Lr (uniformly distributed load pattern)
Span: L = 18'-0"
Member Size: 6 x 14
Species and Stress Grade: Eastern Hemlock, Select Structural
Unbraced Length: Lu = 9'-0"
Assumptions: CM = Ct = CC = CI = Cr = CF = 1.0 (no holes or notches) Bending occurs in the strong direction.
a) What are the dressed dimensions of this beam?
b) Find the slenderness ratio, RB.
c) Ignore the results of question “b” above. Calculate the beam stability factor (CL) using an RB = 20.
Problem 2
Answer the following questions, given a 5 1/8” x 7 ½” glued-laminated column (“stressed primarily in compression”) using the following information and LRFD design procedures:
Critical Load Combination: 1.2D + 1.0W + L
Design Height & Length: 15'-0" (pinned-pinned, Ke = 1.0)
Combination Symbol: 16
Species & Grade: Softwood timber, western species HF, L1
Assumptions:
CM = Ct = CL = Cfu = Cc = CI = Cvr = Cb =1.0
The column is prevented from buckling in the weak direction (it is laterally braced by the wall).
Bending from the lateral load occurs in the strong direction of the column (about the x-x axis).
Individual laminations are 1 ½” thick.
There are no holes or notches.
Distributed Lateral Force: w (wind, W) = 150 PLF
Axial loads: P (dead, D) = 3,100 lbs.
P (live, L) = 4,000 lbs.
Moment = w(L2 ) / 8
a) What is the volume factor, Cv?
b) What is the column nominal Euler critical buckling stress, FcEn?
c) Using a column stability factor, CP = 0.415, determine whether the column is adequate for the combined loading
indicated.
find the needed diagrams for the second problem in the attached files
Sample Solution