internal pressure for structural design

[senthil83]

hi,

i am designing a plated structure where client has specified to use

design internal pressure as 660mmWc at 67% yield strength.

as i am designing the Structure to LRFD - IS it Required to Increase the internal Pressure to 100% yield strength

i.e. 660/0.67 = 985 mm wc for Design of Structural Members?

thanks

 

[JedClampett]

If I'm doing the conversion right, that's over 38 inches of water or 200 psf. This seems pretty high for ASD or LRFD, unless it's blast case or over a very small area with a small effective wind area combined with a hurricane level wind.

 

[JStephen]

Is it repeated loading where fatigue would be an issue?

 

[BAretired]

mmHg is not a unit I normally use, but it appears to me that it is considerably more than 38 inches of water or 200 psf. Is your client planning to detonate a bomb inside this structure?

660mm = 25.98" mercury or 352" H2O = 29.36' H2O = 1832 psf. Wow!

Edit: This is nonsense. See following posts. Please ignore this post!


BA

 

[JStephen]

It says 660mmWc, which I take as 660 mm water column, or about 135 psf.
It didn't indicate this was a building of any kind.

 

[TLHS]

Is this a pressurized process vessel? If it is, it's typical to do the design to the ASME standard, with structural loading being secondary to that using a methodology that can be linked to the ASME allowables or that separates the pressure load path from the load path supporting structure.

 

[BAretired]

It says 660mmWc, which I take as 660 mm water column, or about 135 psf.
It didn't indicate this was a building of any kind.

You are correct. I misread the Wc and assumed Hg. My bad!!!!

BA

 

[delagina]

Why is client asking 0.67FY, where did this come from?

Client maybe using the old ASD-89 0.66FY bending for beam, which should have been 0.75FY bending for plate.

 

[wannabeSE]

Assuming the plated structure is not governed by any building codes, why use LRFD when the client specifies 0.67Fy?

 

[TLHS]

To directly address the question, though, I would make an equivalent load factor for this pressure load if I wanted to use that criteria and LRFD.

If the standard code check for ring tension would be 0.9Fy, I'd set the load factor such that (0.9Fy)/Factor=(2/3)*Fy. So your load factor would be 1.35.