Tank Curb Angle

[Leinster]

Dear All,

I want to size a curb angle on a storage tank based on the tension caused because of the horizontal load of the roof rafters, yet API 650 does not address this. Can anybody advise how these calculations can be done?

 

[JStephen]

The most common rafter arrangements assume that rafters are loaded in bending, not compression, without any significant outward thrust.

For designing for thrust, Roark's Formulas for Stress and Strain has a load case for N equally-spaced outward forces applied to a circular beam.