Wood Column to NDS 2018 - Validation Examples
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
| Parameter | Value |
|---|---|
| Column Size & Grade | 6x6 D.Fir-L No. 1 |
| Column Unbraced Lengths | 12’ |
| Service Conditions | Dry, normal temperature |
| Axial Loads | = 6,800 lb, = 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 | 695 psi / 1,042 psi | 696 psi / 1040 psi |
| Column Stability Factor | 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 | = 10’, 0’ (braced by sheathing for Y-axis buckling and lateral-torsional buckling) |
| Service Conditions | Dry, normal temperature, repeating member |
| Axial Loads | = 1,440 lb, = 640 lb, = 1,440 lb, Self-weight not considered, No Eccentricity |
| Lateral Loads | = 25 psf (specified as = 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 | 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 | 0.377 | 0.376 |
| Allowable Compression Stress | 896 psi | 894 psi |
| Interaction Equation | 0.49 | 0.49 |