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

Effective Flange for Stiffened Plate

Effective Flange for Stiffened Plate

Effective Flange for Stiffened Plate

Very often in ship or oil rig construction, the most efficient way to design a deck is to weld tees or angles to the plating. The plating then acts as the top flange of the beam. The question is ... what width of plating is effective as a top flange. I have seen numerous formulations from the simple 2*sqrt(E/Fy) to others that require loading info and a lot of details. API RP-2A, Norsok, Roarke all give formulations.

I wanted to get a consensus of what others have used in this situation to see if there is one formulation that stands out as popular choice. If anyone has a copy of or knows where to obtain the paper "Thin Walled Structures. Theoretical Solutions and Test Results" by G. Winters 1968 you can let me know.


RE: Effective Flange for Stiffened Plate

According to M.S. Troitsky "Tubular Steel Structures - Theory and Design" published by James F.Lincoln Arc Welding Foundation (P.O.Box 17035, Cleveland, Ohio 44117-0035, Fax 216-361-5901) page 7-28:
"the width of the plate should not exceed:
a. When L/t<40, the actual width center-to-center of stiffeners should be used.
b. When L/t>40, no more then 40t.
In any event, the distance center-to-center of stiffeners should not exceed 80t."
Where L - stiffener spacing,
      t - thickness of plate.

Good luck.

RE: Effective Flange for Stiffened Plate

The US Navy publishes a document MIL-HDBK-264 Properties of Steel Shapes and Plate-Beam Combination Used in Ship Building.  This provides guidance on the effective breadth of plate when used in conjunction with tees, angles, etc welded to plate. This can be ordered through the Department of Defense Single Stock Point www.DODSSP.daps.mil

In general for mild steel the effective breadth of plate is half the distance to the next stiffener each side or 60*thickness whichever is less.  If you have other materials the effective breadth comes from the equation

b= 2*(E/Fy)^.5 *t       Fy=yield  t=plate thickness

RE: Effective Flange for Stiffened Plate

A great reference for effective width issues is Design of Aircraft Structures by Bruhn.  

If I remember correctly, you often find

b(eff) = 1.7 * t * sqrt(E/Fcy) where Fcy is the compressive yield stress (applies to stainless  steel)

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! Already a Member? Login


White Paper - PLM and ERP: Their Respective Roles in Modern Manufacturing
Leading manufacturers are aligning their people, processes, and tools from initial product ideation through to field service. They do so by providing access to product and enterprise data in the context of each person’s domain expertise. However, it can be complicated and costly to unite engineering with the factory and supply chain. Download Now
White Paper - Medical Device Design Control
Medical device product development is a highly integrated and regulated process. Implementation of a requirements tracking solution requires attention to a variety of nuanced topics. When presented with the task of tracking the many concept relationships in a project of this type, the initial software solution of choice tends to be a two-dimensional text systems. Download Now

Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close