Effective Flange for Stiffened Plate
Effective Flange for Stiffened Plate
(OP)
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.
Thanks
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.
Thanks






RE: Effective Flange for Stiffened Plate
"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
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
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)