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# Allowable Stress for I section about their weak Axis

• To: seaoc(--nospam--at)seaoc.org
• Subject: Allowable Stress for I section about their weak Axis
• From: Glauco <glauco(--nospam--at)cenpes.petrobras.com.br>
• Date: Mon, 25 May 1998 09:33:33 -0300

```Hello,

Is this correct?

The Allowable Stress for I section about their weak Axis (z-z):

z____ |_____| _____z
|     |

compact section: b/(2tf)< 65/(Fy)^(1/2)   -> Fb=0.75Fy
non-compact:     b/(2tf)< 95/(Fy)^(1/2)   -> Fb=[1.075-0.005(bf/2tf)Fy^1/2]Fy
slender:         b/(2tf)> 95/(Fy)^(1/2)   -> Fb=0.60Fy*Qs

for: 195/(Fy/kc)^(1/2)< b/(2tf)< 195/(Fy/kc)^(1/2)
-> Qs=1.293-0.00309(b/t)(Fy/kc)^(1/2)

b/(2tf)> 195/(Fy/kc)^(1/2)  -> Qs=26200kc/[Fy(b/t)^(1/2)]

where: kc=4.05/(h/t)^0.46 if h/t > 70, otherwise kc=1.0

In the evaluation of kc the value of h is the clear distance between flanges
(d-2*tf) and t the thickness of the flange(tf)? or h the flange width and t the
thickness of the web?

Thanks,

```