Project Phase 3
Check the components in your wood structure that carry the largest loads. For the sample house this would include:
1. ceiling joist 2x8 bending with D, L Lr 2. floor/ceiling joist 2x10 bending with D, L Lr 3. rafter 2x8 bending with D, Lr, S 4. stud in first-floor interior wall 2x4 axial compression with D, Lr, S, L 5. stud in first-floor exterior side wall 2x6 axial compression and bending with D, Lr, S, L, W 6. connection between first-floor interior wall stud and bottom plate 2x4 bearing with D, Lr, S, L Utilize the adjusted design values that you derived in Phase 2 or derive new ones. If the trial member size used in Phase 1 is too small, find a satisfactory member size. Or, if the trial size is excessive, suggest a cheaper alternative. If you are dealing with a custom structure or a modification of the sample house, load calculations for the sample house are provided for comparison.
Please submit a printed or emailed report (or memo) by class time next Tuesday, April 2. Please include a summary table with the following information. Detailed stress calculations (similar to the chapter 6 and 7 homework derivations) can be included in the body of the report or in appendices.
- a list of the components you analyzed (where was the component in the structure?)
- the trial member size for each component (2x4, 2x10, etc)
- whether or not the trial member size was satisfactory; if the trial size was too large or too small, list a better alterative
- actual stress(es) (axial tension, axial compression, bending, bearing, etc) versus adjusted design value(s) for the controlling load combination for each component (using homework problem 7.8 as an example: fb = 1,039 psi ≤ 1,275 psi ✓ for controlling load combination (D+Lr))
Alternatives to try in the future
- eliminate any adjustments that increase reference capacity (only use Cd for dead loads, Cp for studs) and compare to the answers for the above situations
- change the spacing from 16-in. OC to 24-in. OC and compare
- use LRFD and compare
- try no lateral support (foam sheathing)
- compare to IRC size recommendations