Shear Strength of Wide Flange Steel Beams
Shear Strength of Wide Flange Steel Beams
(OP)
In codes, text books we can find well established curves between the critical shear stress and the shear slenderness. In industrial field, it is common to have beam flanges coped at ends and connected to perpendicular beams with end plates and bolts. The coped length can be anywhere from say 3” to 12”. Can anybody advise how to calculate the local shear buckling strength (of the coped segment) and the entire shear buckling strength of this kind beams?
Thanks in advance.
Thanks in advance.






RE: Shear Strength of Wide Flange Steel Beams
I have done more sophisticated calculations considering bi-axial bending and torsion. In these cases I reverted to basic strength of materials using the following equation:
Stress = (Sx+Sy/2) + or – [(Sx-Sy)^2 + Tau^2]^0.5
Good luck
RE: Shear Strength of Wide Flange Steel Beams
Basically, when the beam is coped, one has a situation which involves block shear and tension at the connection. The AISC contains a full explanation on the design for coped section.
RE: Shear Strength of Wide Flange Steel Beams
1. Gross cross section of the web
2. Net cross section of the web (minus the bolt holes)
3. Capacity of the bolts in shear
4. Capacity of the clips in shear
5. capacity of the perpendicular beam in shear
6. Bolt tearout distances
7. Web Crippling...
The designer has to determine the mode of failure before the faiure load can be stated.
As for crippling of the web within a bolt group, this is unlikely since the short web length (between the bolt holes) will not follow "typicaly buckling formulas" due to the length :width ratio being too low. This becomes a shear or crushing mode of failure. As for other locations where there are large concentrated loads on beams, buckling of the web may occur due to sufficient length:width ratios thus the reason for bearing stiffeners or traverse stiffeners where the calcualtions dictate or for "good practice".
(Most Steel handbooks have design data for eccentric loads on weld or bolt groups)
RE: Shear Strength of Wide Flange Steel Beams
I used Eq. A-F2-1, A-F2-2 and A-F2-3 of AISC LRFD Specification to calculate the shear strength Vr of wide flange beams and used the procedure described in Part 9, DESIGN OF CONNECTION ELEMENTS, of AISC steel construction manual (LRFD) to calculate Vr of beams with flange coping.
It’s interesting to notice, based on the calculation, that Vr of a WF beam without coping is much higher than that with even one flange coped, although in Vr calculation we consider only the web to resist the shear force. In addition, Vr of a WF beam with both flanges coped is much lower than the beam with only one flange coping.
RE: Shear Strength of Wide Flange Steel Beams
When the beam is coped, you not only "loose" the flange, but also a portion of the (shear calculation) web. This explains your observation that shear capacity goes down when one side is coped, and goes down even more when both sides are coped.
RE: Shear Strength of Wide Flange Steel Beams
Taking the W12x50 beam as an example. With full section, Vr = 124 kips. When the top flange is coped 2” deep by 6” long, Vr = 80 kips. If both flanges have the same coping, Vr = 32 kips!