Validation and design examples for wood columns per NDS 2018. Note that values will vary slightly (+/- 1%) due to round-off errors.

Example 1 - Sawn Lumber Column using ASD and LRFD

Reference: Abi Aghayere and Jason Vigil, Structural Wood Design, 2nd Edition, 2017, Taylor & Francis, Example 5.6, p. 299

Inputs

Parameter Value Column Size & Grade 6x6 D.Fir-L No. 1 Column Unbraced Lengths L x = L y = L_x = L_y = Lx​=Ly​= 12' Service Conditions Dry, normal temperature Axial Loads D D D = 6,800 lb, S S S = 10,200 lb, Self-weight not considered, No eccentricity

Outputs

Result Example (ASD/LRFD) ClearCalcs (ASD/LRFD) Design Load 17,000 lb / 24,500 lb 17,000 lb / 24,500 lb Buckling Stress F c E F_{cE} FcE​ 695 psi / 1,042 psi 696 psi / 1040 psi Column Stability Factor C p C_p Cp​ 0.502 / 0.502 0.503 / 0.501 Allowable Column Capacity* 17,463 lb / 26,300 lb 17,497 lb / 26,205 lb

Example 2 - Exterior Stud Wall Using ASD

Reference: Abi Aghayere and Jason Vigil, Structural Wood Design, 2nd Edition, 2017, Taylor & Francis, Example 5.9, p. 313

Inputs

Parameter Value Column Size & Grade 2x6 D.Fir-L No. 2 @ 2' o.c. Column Unbraced Lengths L x L_x Lx​ = 10', L y = L_y = Ly​= 0' (braced by sheathing for Y-axis buckling and lateral-torsional buckling) Service Conditions Dry, normal temperature, repeating member Axial Loads D D D = 1,440 lb, L L L = 640 lb, S S S = 1,440 lb, Self-weight not considered, No Eccentricity Lateral Loads W W W = 25 psf (specified as 0.6 W 0.6W 0.6W = 15 psf in the example)

Outputs

The example splits into 4 main design checks (the first one is ignored as it checks for net section bearing stress which is irrelevant in this case)

Design Check 2 - Pure Axial Loading and Bearing

Result Example ClearCalcs Governing Load Case D + 0.75(L + S) D + 0.75(L + S) Governing Axial Load 3,000 lb 3,000 lb Column Stability Factor C p C_p Cp​ 0.492 0.491 Allowable Compression Stress 840 psi 839 psi Allowable Bearing Stress 625 psi 625 psi Utilization Ratio * 43.3% 43.3%

*Since the example deals with stresses and ClearCalcs deals with loads, we compare the utilization ratio to show that the results are exactly the same.

Design Check 3 - Pure Bending

Result Example ClearCalcs Governing Load Case D + 0.6W D + 0.6W Governing Moment 4,500 in-lb = 375 lb-ft 375 lb-ft Allowable Bending Stress 2,153 psi 2,153 psi Utilization Ratio * 27.6% 27.6%

*Since the example deals with stresses and ClearCalcs deals with loads, we compare the utilization ratio to show that the results are exactly the same.

Design Check 4 - Combined Loading

Result Example ClearCalcs Governing Load Case D + 0.75(L + S + 0.6W) D + 0.75(L + S + 0.6W) Governing Axial Load 3,000 lb 3,000 lb Governing Moment 3,375 lb-in = 281.25 lb-ft 281.25 lb-ft Allowable Bending Stress 2,153 psi 2,153 psi Column Stability Factor C p C_p Cp​ 0.377 0.376 Allowable Compression Stress 896 psi 894 psi Interaction Equation 0.49 0.49