×
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

Figuring for Wood Girts

Figuring for Wood Girts

Figuring for Wood Girts

(OP)
Hello all new here and to the industry.

I am trying to find any information on wood girt design. I am in the steel industry and have a customer that is using 2x10 wood for girts. The buiding is a 30LL 16' Bay Spacing, 90MPH Exp B building, 2' OC Purlin/Girts. His permit department needs our drawings to say that 2x6 will work for his girts although he is going to use 2x10's. Any help with this would be greatly appriciated.

RE: Figuring for Wood Girts

I assume these are wall girts turned flat to the wind.  Roof purlins are typically upright.  If so - not a problem!!

Even a 2x10 flat to the wind at 16' span maybe problematic.

Say 10 psf wind - minimum - adjust if needed
24'' o.c. = 20 plf

M = wL^2 /8

M = 640 ft-lbs x 12 = 7680 in-lbs

Fb = M / S        Syy - 2x10 flat = 3.468 in^3

Fb = 7680 / 3.468
Fb = 2214 psi / 1.33 reduction for wind = 1665 psi

So you need a fairly good grade of 2x10.  Some codes allow for a 1.6 wind reduction instead of 1.33.  That will help if applicable.

I got you this far - now check for deflection - that could be a real problem.  

Good Luck

RE: Figuring for Wood Girts

(OP)
No they will be on edge to wind. Does that change things??

RE: Figuring for Wood Girts

OH YES!!!

The section modulus - Sxx - just went up to 21.4 in^3

SO NO PROBLEM - either in bending or deflection

RE: Figuring for Wood Girts

Sag of the girts under dead load could be an issue.

You either need adequate bridging to take this or you need to design them for biaxial loading and for buckling along the full length.

RE: Figuring for Wood Girts

CSD72 -

Good Point - I am hoping sheathing will take care of that

RE: Figuring for Wood Girts

only if the sheathing is on both sides otherwise there be a tendency for them to twist.

 

RE: Figuring for Wood Girts

Can the sheathing hang from a beam at the eave? There should be a member there to handle collector loads anyway... If the collector member and sheathing connections are designed to hang the full weight of the sheathing, there will be minimal weak-axis bending on the wood girts below.

RE: Figuring for Wood Girts

The only dead load the girts will see will be their own self-weight and the weight of the sheeting.  Most of the load from the sheeting will be transferred to the lowest gort that will probably be a sill plate.  That should support this dead load.  

Regarding the twisting action csd refers to, just add vertical blocking at midspan.  This coupled with the girt end connections should suffice.

Mike McCann
MMC Engineering

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