Design of long width steel plate

[laohan2]

Hi,

I'm designing a large steel plate (6.1m x 3m) simply supported on the short side, under uniform distributed loading and need to calculate the required plate thickness.

Normally I would calculate the bending capacity and the section modulus S=bd^2/6. For this case, would my design width (b) be 6.1m? or should I apply a smaller effective width?

 

[Agent666]

The plate won't buckle if bent about the minor axis. Therefore you could use the plastic modulus not the elastic modulus

Regarding the width, it really depends on the loading, if it is a uniformly distributed load over the entire surface then just calculate on a unit width basis, the answer will be the same if you use 1mm or 6100mm.

If there is some two-way action from for example a point load then you'd need to investigate this and it really turns into more of a yield line analysis.

https://engineervsheep.com

 

[JoelTXCive]

Agent666 is correct. The formulas are in section F11 of the steel manual.

Also, check out this software....It's super easy to use and has a 30day free trial...

https://www.iesweb.com/vp/index.html

Visual Plate by IES Web
(sometimes I feel like a salesperson for them, but I'm not. I'm just a big fan of their products. They are cheap and easy to use)

 

[centondollar]

If your plate is simply supported on the short side (3.1m) and unsupported on the long sides (6.1m), the plate is spanning in the long direction and the "effective width" you mention is related to the short side (3.1m). The effective width is not used for a flat plate though, since there will not exist shear lag in a 2-1 aspect ratio uniform plate - it acts as a plate, not as a part of a beam.

Also, making an unstiffened steel plate with the spans you propose is likely to be highly uneconomical. Make it orthotropic with deep one-sided stiffeners in the longitudinal direction if you want a sensible design. Better yet, use two hot-rolled I-beams and add a plate with transverse stiffeners to distribute the load to the beams.