Allowable Shear in Beam Table vs Equ. F4-1
Allowable Shear in Beam Table vs Equ. F4-1
(OP)
I am looking at the value in the beam tables for A36 channels C15x40. The allowable load where shear starts to control is 225k. When I use F4-1 i only get a allowable of 87.3k. Where am I missing something? I'm using the dimensions "T" and "tw" for the area of the web. Thanks.





RE: Allowable Shear in Beam Table vs Equ. F4-1
Although this won't be terribly useful to AISC & Eq F4.1, following the CSA standard, this channel would have a pure shear capacity of 746 kN (168k) at yield of 250 MPa (36 ksi) - this is factored & follows a limit state design philosophy. However if considering web crippling & web yielding effects, these could govern depending on stiffeners & bearing length.
Hope this doesn't confuse, but may make an interesting comparison.
DRW75
RE: Allowable Shear in Beam Table vs Equ. F4-1
RE: Allowable Shear in Beam Table vs Equ. F4-1
0.40*Fy*d*tw = 0.4*36ksi*15"*0.52" = 112.3 kips
The table gives an allowable load on the beam of 225 kips. Assuming a uniformly loaded, simply supported single span beam, the shear at each end is 225/2 = 112.5 kips
RE: Allowable Shear in Beam Table vs Equ. F4-1
RE: Allowable Shear in Beam Table vs Equ. F4-1
For a C15x40
d = 15"
tw = 0.52"
Fy = 36 ksi
h/tw = 15/.52 = 28.84
380/sqrt(Fy) = 380 / sqrt(36) = 63.33 therefore F4-1 valid to use.
Fv = 0.4 x 36 = 14.4 ksi
Max shear on C15 = Fv x d x tw = 14.4 x 15 x .52
= 112.32 kips
Beam table max load = 225 kips
225 / 2 = 112.5 kips max. end reaction
RE: Allowable Shear in Beam Table vs Equ. F4-1
The CISC allows for 0.66 shear factor and a material factor of 0.9.
I assume that it is simply the difference between LRFD & limit states.
DRW75
RE: Allowable Shear in Beam Table vs Equ. F4-1