A992 Structural Steel

[TankDude]

I am design a structural cone roof for an API-650 tank and I am using A992 structural steel. Since API-650 doesn't appear to list this material (nor it's predecessor A572), I am a little confused about the design stress that I should use. API620 lists this material as having an equivalent design stress to A36 (per table 5-1), but I was planning to simply use the AISC-ASD method of taking 0.66Fy as the design stress (assuming of course that my section meets compactness criteria). Does anyone have an opinion on this? Would it still be considered as meeting API650 criteria? Thanks in advance.

 

[JStephen]

API hasn't listed allowable stresses for structural members for a while- it just refers you to AISC, and that's where the stresses would come from. See 3.10.3.1 in Addendum 4. A992 is shown as one of the materials in 2.4.1(c).

Be sure to check the API-650 requirement about lateral stability with dead load- that will control rafter design in many cases.

 

[IFRs]

Lateral stability can be increased by adding additional braces.