Steel Roof Tank Modification 2

[Luk]

Hi there!

My client is asking me to replace an existing square shaped manhole at the top of a flat steel roof tank, with a new circular steel flanges. The steel flanges weigh more than the manhole.
Does anyone has any idea how I should go about analysing the roof tank steel plate capacity?
I'm having a crash course on Roark's methods
Thanks!

 

[JedClampett]

If the tank is small, the top might be supported by the side walls and you probably need Roark. If it is larger, it will have framing members supporting the roof. I'd be lazy and add a doubler ring to make up the area you're removing. Then check the plate as simply supported between supports or side walls.

 

[boo1]

The stress risers for the rounded corners wil be less than the sq. ones. The stress and strain distribution concentration factors can be found in Stress Concentration Factors: Perterson. Look at the circumference of a hole in an orthotropic sheet under any combination of in-plane direct and shear loading.

Agree with Jed, use doublers at the openings.

 

[Luk]

Thanks guys for the reply.
I will look at "Stress Concentration Factors: Perterson".
Cheers,
Luk