Wide Flange Weak Axis Shear Capacity 1

[KBVT]

I'm looking at a wide flange beam loaded about its weak axis and attempting to calculate the shear capacity. Is the correct method of analysis to substitute bf/tf in all of the web shear coefficient calculation equations? I am looking at AISC G.7 which refers back to G.2. The way I am reading this is to calculate the shear capacity of each flange (using Phi = 0.9) and add them together to come up with the full weak-axis shear capacity. I just want to verify that I am using the correct ratios for the flange slenderness calculations.

 

[Lion06]

That's how I would do it. You'll likely encounter few problems for shear since the b/t ratios are lower for the flanges than for the web. Additionally, because of the lower S value, bending is even more likely to govern than in most cases (or deflection).

 

[frv]

Looks right to me

 

[KBVT]

Thanks guys, I've actually never seen shear control in weak-axis bending but I wanted to make sure the calcs all matched up.

 

[frv]

One note of caution: make sure you resolve your shear out of the beam. Remember that most beams are connected through the web. Here, you are carrying your shear through the flanges and they must, in turn, transfer the shear out to the column or wall.

That's a really long way of suggesting you connect the flanges to the supporting member.

 

[graybeach]

Actually, the maximum shear stress in the flanges when the beam is loaded in the weak direction is more like 3/2 V / (sum of flange areas). The shear stress in the web of a wide flange loaded in the strong direction is approximately V/(d*tw) because the presence of the flanges make the shear flow calculations work out that way.
I do not often see this taken into account except in wood.