Foundations and Retaining Walls

Wood Column to NDS 2018 - Validation Examples

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

ParameterValue
Column Size & Grade6x6 D.Fir-L No. 1
Column Unbraced Lengths L x = L y = L_x = L_y = 12'
Service ConditionsDry, normal temperature
Axial Loads D D = 6,800 lb, S S = 10,200 lb, Self-weight not considered, No eccentricity

Outputs

ResultExample (ASD/LRFD)ClearCalcs (ASD/LRFD)
Design Load17,000 lb / 24,500 lb17,000 lb / 24,500 lb
Buckling Stress F c E F_{cE} 695 psi / 1,042 psi696 psi / 1040 psi
Column Stability Factor C p C_p 0.502 / 0.5020.503 / 0.501
Allowable Column Capacity*17,463 lb / 26,300 lb17,497 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

ParameterValue
Column Size & Grade2x6 D.Fir-L No. 2 @ 2' o.c.
Column Unbraced Lengths L x L_x = 10', L y = L_y = 0' (braced by sheathing for Y-axis buckling and lateral-torsional buckling)
Service ConditionsDry, normal temperature, repeating member
Axial Loads D D = 1,440 lb, L L = 640 lb, S S = 1,440 lb, Self-weight not considered, No Eccentricity
Lateral Loads W W = 25 psf (specified as 0.6 W 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

ResultExampleClearCalcs
Governing Load CaseD + 0.75(L + S)D + 0.75(L + S)
Governing Axial Load3,000 lb3,000 lb
Column Stability Factor C p C_p 0.4920.491
Allowable Compression Stress840 psi839 psi
Allowable Bearing Stress625 psi625 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

ResultExampleClearCalcs
Governing Load CaseD + 0.6WD + 0.6W
Governing Moment4,500 in-lb = 375 lb-ft375 lb-ft
Allowable Bending Stress2,153 psi2,153 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

ResultExampleClearCalcs
Governing Load CaseD + 0.75(L + S + 0.6W)D + 0.75(L + S + 0.6W)
Governing Axial Load3,000 lb3,000 lb
Governing Moment3,375 lb-in = 281.25 lb-ft281.25 lb-ft
Allowable Bending Stress2,153 psi2,153 psi
Column Stability Factor C p C_p 0.3770.376
Allowable Compression Stress896 psi894 psi
Interaction Equation0.490.49

Get in Touch with ClearCalcs

Chat with our Customer Success team and get product or account support directly to your inbox.

Contact Us