beam section capacity check at big bending moment and shear force by use of AISC 360-10 1

[TTTKAO]

Hello Friends,

Does anyone can advice how to check section capacity at a spot with big bending moment and shear force relatively by using of AISC 360-10 code ? I only found check the bending strength capacity as per chapter F and shear capacity as per chapter G separately.

1. Is there any requirement or combined equations to check existing moment and shear at the same time? such as Canadian code requirement CAS-S16-01 items 14.6. seems this combined load check is required by other nation code as well, is there any reason there is no requirement in AISC360-10 or i didn't find correct item to check ?

2. this is relating to item 1, for the built-beam or cover plate connecting weld size check, only shear force stress check at the weld location as per AISC chapter F13, there is bending stress existing, why this is not considered ?

Thank you in advice for your input and advice.

Regards!

 

[ProgrammingPE]

1. AISC 360 does not include a check for combined shear and flexure. If it did, it would be located in Chapter H - Design of Members for Combined Forces and Torsion. The commentary for Section H3.3 (Non-HSS Members Subject to Torsion and Combined Stress) mentions that yielding under normal stress and shear stress are considered separately:

"In most cases it is sufficient to consider normal stresses and shear stresses separately because maximum values rarely occur in the same place in the cross section or at the same place in the span."

For a wide-flange, the maximum bending stress is in the flange and the maximum shear stress is in the web. Also, for simply supported beams the maximum shear is at the supports and the maximum moment is near midspan. This is how they justify not including a combined shear and flexure check.

2. The welds between a beam and its cover plate need to be designed to transfer the horizontal shear between the beam and the cover plate so that they behave compositely. There also needs to be enough welds at the end of the cover plate so that it is engaged at the cut off point where it is required.

When you say "bending stress" in the welds, are you talking about stress parallel to the weld axis? If so, then that stress is permitted to be ignored per Table J2.5.

(Thanks KootK for the image from this thread.)


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[TTTKAO]

Thank you ProgrammingPE.

 

[KootK]

Thanks KootK for the image

No sweat. The recycling of a sketch further justifies the original effort. Thanks for the plug.