Calculating deflection of simply supported sheet metal

[galacticspecofgoo]

Hi,

I'm a little rusty and I'm trying to figure out how to correctly determine the correct thickness of sheet metal to use on custom concrete formwork. For example purposes, lets say my supports are 12" o.c and I'm looking at a UDL of 1000 psf. I'm using 3mm sheet metal (11 gauge I believe).

Is there a simple formula for determining this? I've searched for a while and it seams it may not be straight forward.

Thanks for any help in advance.

 

[dik]

Not likely something that will give you a meaningful answer. Your system will most likely behave like a membrane and not a flexural plate item.

YOu might discuss this with a checker plate supplier or someone of that ilk and get an idea of how they implement in-plane stresses.

Dik

 

[desertfox]

Hi galactic

You might want to look at this link it may help you get an approximate answer:-

http://www.xcalcs.com/cgi-bin/tutti/x2calcs.cgi?d=i_4_0_2_0_0&l=en

desertfox

 

[BAretired]

If the horizontal span is 12" and the vertical span is very large (say more than 48") you could treat it as a continuous horizontal span. The flexural rigidity D of the plate is Eh³/12(1-[ν]²) where E is Young's Modulus, h is thickness and [ν] is Poisson's ratio (0.3 for steel). For steel, D is approximately 1.1*EI.

BA

 

[RHTPE]

The two major US steel form manufacturers use 3/16" skin material with supports at 12" c/c and their systems are rated at 1,500 psf. I would consider the life expectancy that you're trying to achieve (if any) - steel forms suffer from more abuse simply by virtue of the fact they're made of steel. You need to consider connections as well - will the welds affect the surface of your form facing? And then there's the reconditioning after being used & abused - your 1/8" skin will be more easily 'stretched' and more difficult to recondition back to a flat surface.


Ralph
Structures Consulting
Northeast USA