×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Wooden boards - im getting crazy...

Wooden boards - im getting crazy...

Wooden boards - im getting crazy...

(OP)
How do you guys design this?
Lets say we have wooden boards - no spacing between them,
Single board dimensions are: b/h = 200/50 mm




Area load is: q = 3,00 kN/m2
That means that a load per single wooden board is: q' = q x e = 3,00 kN/m2 x 0,20 m = 0,60 kN/m
where e is a distance from center to center of boards.


In model 1 I have area/surface model with an area load and in model 2 i have a simply supported beam (a single board)
Why do i get different bending moments/shear forces...

model 1: Moments = 1,51 kNm/m x 0,20 m = 0,30 kNm is the same as model 2
model 1: Shear = 4,79 kN/m x 0,20 m = 0,96 kN is NOT the same as model 1 (0,60 kN)

Im getting crazy since im working 10 hours straight...




RE: Wooden boards - im getting crazy...

Off the top, for normal loading, the span for 50mm would be approx 2m. The lumber dimensions are normally nominal and a 2" (50mm) board is actually 1-1/2" (38mm). Also the width is 7-1/4" (???mm) and not 8" (approx 200mm). If you space them at 8" (200mm) you may have a 3/4" gap between them. You need clarification from the designer.

Dik

RE: Wooden boards - im getting crazy...

Calculate shear by hand and be done with it. Why are you mixing so many methods for a simple span beam ?

RE: Wooden boards - im getting crazy...

Quote (molibden)

Calculate shear by hand and be done with it. Why are you mixing so many methods for a simple span beam ?
I agree. Turn off your computer!

RE: Wooden boards - im getting crazy...

For 1m width,
M = wl2/8 = 3(2)2/8 = 1.5 kNm (not 1.51 kNm)
V = wl/2 = 3*2/2 = 3 kN (not 4.79 kN)

For a 200mm wide board, the values would be 20% of the above provided the boards are fastened together with tongue and groove joints or other means of ensuring that the load is spread over several boards. If the boards are not fastened together, it is possible to overload one board with a concentrated load falling within its width.

BA

RE: Wooden boards - im getting crazy...

Oh come on, just use decking tables. No one is milling square edged lumber to your dimensions for your project. If you can't find the tables where you are, contact the Canadian Wood Council.

RE: Wooden boards - im getting crazy...

The project may not be in Canada but similar tables are likely available in most countries.

BA

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources