Minimum Stiffener for Stability
Minimum Stiffener for Stability
(OP)
Hello. I have a raised beam connection with a W12X30 end that bears on top of a W16X67 and then a W10x33 column below the W16. Similar to 13th Ed. AISC Manual Fig. 10-31(b). There is a minimal concentrated load of 15k acting on top of the W12. I do not think stiffeners are required for strength because the load is so low. However, I would like to provide full depth stiffeners for rotational stability of the W12 and W16. Rotational stability is required per specification section J and Appendix 6 according to my interpretation. What is the minimum stiffener required for stability? I was thinking of applying Appendix 6 (Stability Bracing for Columns and Beams). Assume a framed structure with W12 and W16 beams. Calculate the required nodal brace system stiffness. Then size the stiffener plate such that is has the same lateral stiffness.
I think the load is so low that it will not matter, but I would just like to know the proper way to do the design. I would guess that I will use a 3/8" full depth stiffener with 3/16" welds as a minimum.
Thenk you very much for any input you can provide!
I think the load is so low that it will not matter, but I would just like to know the proper way to do the design. I would guess that I will use a 3/8" full depth stiffener with 3/16" welds as a minimum.
Thenk you very much for any input you can provide!






RE: Minimum Stiffener for Stability
RE: Minimum Stiffener for Stability
RE: Minimum Stiffener for Stability
J.10 FLANGES AND WEBS WITH CONCENTRATED FORCES
AISC 360-10
RE: Minimum Stiffener for Stability
Am I correct in thinking that some sort of stability bracing should be provided? Full depth stiffeners would provide rotational stability. Appendix 6 seems to talk about that.
RE: Minimum Stiffener for Stability
So a more logical approach would involve a mechanism where the top flange is horizontally displaced respect the bottom flange and then at such predeformed shape of the cross-section check that the section plus the added stiffeners remain stable under the (factored) applied load. This is tantamount to a P-Delta moment atop the height of the stiffeners, plus the axial force (everything factored) and then check the strength of what provided. It was usual that I remember to take 9 times the thickness from the stiffener collaborating, but you can go for more modern web crippling statements of the strength. So really we will be combining in one check both web crippling under the load and LTB prevention.