Design data:

Floor area supported by column: A = 80 ft^{2}

Unsupported length of column, L = 10 ft

Hinge support at top and bottom of column

Design load:

Floor live load: W_{L} = 30 psf

Floor dead load: W_{D} = 10 psf

Superimposed dead load: W_{SD} = 5 psf

Timber: Southern pine, moisture less than 19%, used in normal room temperature.

Refer to Design of Sawn Timber Columns and Compressive Members article for concepts.

1. Select southern pine, 4"x4" stud grade, d = 3.5 in

Actual cross section: A_{c} = 12.25 in2.

Allowable compressive stress parallel to grain: F_{c} = 975 psi

2. Calculate slenderness ratio: K_{e} = 1, L_{e} =K_{e}´L = 10 ft, L_{e}/d = 34 < 50

3. Calculate compressive stress with load duration factor

Load duration factor for dead load: C_{D} = 0.9

Load duration factors for live load: C_{D} = 1.0

Calculate Design load: P = [W_{D} + W_{SD}+ W_{L}]´A = 3600 lb

Column compressive stress, f_{c}=P/A_{c} = 293.8 psi

4. Calculate allowable stress without C_{p}.

C_{M}=1, C_{t}=1, C_{f}=1

F_{c}* = F_{c}´C_{M}´C_{t}´C_{F} = 975 psi

5. Calculate elasticity modulus

E’=E´CM´Ct = 1.4´10^{6} psi

6. Calculate F_{cE}

K_{cE}=0.3

F_{cE}= K_{cE}*E’/(L_{e}/d)^{2}= 357.3 psi

7. Calculate C_{p}

c = 0.8

C_{p} = 0.333

8. Calculate allowable compressive stress

F”_{c} = F_{c}*´C_{p} = 324.8 psi > f_{c}= 293.8 psi O.K.

- Design of Sawn Timber Columns and Compressive Members
- Solved Example: Design of Timber Load Bearing Stud Wall
- Design of Sawn Timber Beams or Joists
- Solved Example: Design of 2x10 Timber Floor Joist with Southern Pine
- Solved Example: Design of 3-3x12 Timber Beam with Southern Pine