Bi-Axial Bending with no Axial Load

[krus1972]

Section "H" of the AISC (9th Edition) states that stresses produced from bending about each axes (X-X & Y-Y) AND Axial (Fa) should be checked together with the formulas shown in the section.

My question is, section H says these formulas should be used ONLY if axial load (fa) is present. I have a beam that has bending about both X-X & Y-Y axes at the same time WITHOUT any axial load.

Since the AISC in section "H1" states that these formulas should be used only when Axial load is present do I need to still check bending interaction using these equations and just make Fa = 0 ? OR do I just check bending about each axis seperately and not worry about interaction?

Thanks,

Jeff

 

[JAE]

Where does section H say that you have to have axial? I don't see it directly.

section H1 states that for members with BOTH axial and bending, use H1-1 and H1-2.

Then it says that if fa/Fa <= 0.15, you use H1-3. So with fa = 0, you would use H1-3.

That's how I'd read it.

 

[krus1972]

Jae,

It says in the title "Axial Compression and Bending". It also says "Members subject to BOTH Axial & Bending...."


My member is not subjected to any Axial Load. Only Bending in each direction. So section H1 does not apply since my member is not subjected to axial load as the first line suggests.

Jeff

 

[JAE]

Follow my logic in my first post above....Yes, the title says axial - but for biaxial bending you still use H1-3.

Just pretend you have 1 small little pound of axial compression and your sure to be in conformance.