Warning: Stiffeners on gusset are required due to free edge buckling

RE: Warning: Stiffeners on gusset are required due to free edge buckling

Carlos Perez — Tue, 14 Mar 2023 14:50:50 GMT

That reference is for course that Prof. Engelhardt did together with the AISC about seismic connections, attached the pdf of the presentation about concentrically braced frames.
communities.bentley.com/.../AISC_5F00_Seismic_5F00_Design_2D00_Module3_2D00_Concentrically_5F00_Braced_5F00_Frames.pdf

RE: Warning: Stiffeners on gusset are required due to free edge buckling

Nazmul Haq — Tue, 14 Mar 2023 10:40:19 GMT

Can you share the reference book for SCBF,

RE: Warning: Stiffeners on gusset are required due to free edge buckling

Jason McCool — Mon, 13 Mar 2023 13:47:46 GMT

Excellent. I knew I hadn't seen it come up in quite a while on any of our projects, so it surprised me to see the topic again after all this time. Thanks, Carlos!

RE: Warning: Stiffeners on gusset are required due to free edge buckling

Carlos Perez — Mon, 13 Mar 2023 13:02:37 GMT

Hello Jason and Nazmul Jaq, RAM Connection supports different design codes that have specifications that have changed in newer versions, the free edge buckling is only included in AISC 360-05 (AISC 341-05) where it was included and it is NOT included for AISC 360-10 (AISC 341-10) nor AISC 360-16 (AISC 341-16) due to reasons Jason detailed, if you switch the code from AISC 360-05 to AISC 360-10 or AISC 360-16 the warning will not be reported.

RE: Warning: Stiffeners on gusset are required due to free edge buckling

Jason McCool — Sun, 12 Mar 2023 23:15:28 GMT

Why are you referencing anything from the 1st edition SDM? AISC took out that entire requirement for stiffeners for free edge buckling in the 2nd edition 13 years ago. As noted in the Commentary to section F2.6c, "The committee has reviewed the testing cited and has concluded that such edge stiffeners do not offer an advantages in gusset plate behavior. There is therefore no limitation on edge dimensions in these [2010] provisions." AISC later reiterated this with a little more background info in their March 2013 Steel Interchange column (emphasis added):

"The use of intermediate stiffeners in the gusset plate and the corresponding stiffeners at the gusset edges is based on a 1998 publication in the Steel Tips series. It recommends a maximum free edge buckling length, but if this maximum length was exceeded, there were not any recommendations on how to size or connect these stiffeners. The result is that “nominal” stiffeners and welds were used with little research or design guidance to justify the design. Example 3.10 in the 1st Edition of the AISC Seismic Design Manual includes these stiffeners because the free edge criterion is exceeded, and the stiffeners and welds are sized and shown on the final figure (Figure 3-14). However, these sizes are simply stated as nominal values using normal plates and corresponding weld sizes. Later research and investigation into the requirements for these stiffeners, intended to improve the guidance provided, has actually changed the current thinking. It is now thought that these stiffeners do not serve the purpose they were proposed to serve and that the gussets do not have free edge buckling problems. Furthermore, use of stiffeners to limit the free edge length may actually be detrimental to the performance of the connection as they introduce a point of high local stiffness and can have the tendency to increase and concentrate deformational demands at the stiffener location. As a result, the free edge buckling check has been removed in the 2nd Edition AISC Seismic Design Manual examples. The technical justification for this is provided in the Commentary to Section F2.6c in AISC 341-10: “Certain references suggest limiting the free edge length of gusset plates, including SCBF brace-to-beam connection design examples in the Seismic Design Manual, (AISC, 2006), and other references (Astaneh-Asl et al., 2006; ICC, 2006). However, the committee has reviewed the testing cited and has concluded that such edge stiffeners do not offer any advantages in gusset plate behavior. There is therefore no limitation on edge dimensions in these provisions.” Therefore, it is AISC’s recommendation that stiffeners not be used to limit the free edge length of gusset plates in OCBFs or SCBFs." - Heath Mitchell, S.E., P.E.

Has that requirement been reinstated since the removal in 2010? I'm assuming Bentley is just not staying up-to-date since you referenced the 2005 edition instead of any newer version. Gotta stay current if you want people to pay you for your software....

RE: Warning: Stiffeners on gusset are required due to free edge buckling

Modestas — Thu, 09 Mar 2023 13:20:44 GMT

We check the equations pasted below from the Seismic Design Manual p3-63. The first edition of the manual corresponds to the AISC 341-05.

The gusset plate stiffeners are not provided by the program and the user needs to take care of it manually.

RE: Warning: Stiffeners on gusset are required due to free edge buckling

Nazmul Haq — Thu, 09 Mar 2023 02:44:48 GMT

Increasing the thickness is the only way ???!!! Solving by increasing thickness requires too much thickness which does not seem logical. Can you check kindly? Is there any option to add a stiffener? What is the equation for this warning?

RE: Warning: Stiffeners on gusset are required due to free edge buckling

Modestas — Tue, 07 Mar 2023 13:18:24 GMT

This question was answered here: Warning: No input found for welding thickness change - RAM | STAAD Forum - RAM | STAAD | ADINA - Bentley Communities

RE: Warning: Stiffeners on gusset are required due to free edge buckling

Nazmul Haq — Tue, 07 Mar 2023 03:25:56 GMT

communities.bentley.com/.../7875.Gusset.rarsee the attachment.

RE: Warning: Stiffeners on gusset are required due to free edge buckling

Abhisek M — Mon, 06 Mar 2023 08:14:10 GMT

The file you have shared contains some user defined sections and hence I am unable to run it. Can you please provide the section properties as well? Or can you duplicate it with standard sections?

RE: Warning: Stiffeners on gusset are required due to free edge buckling

Nazmul Haq — Sun, 05 Mar 2023 03:15:47 GMT

communities.bentley.com/.../Gusset.rar See the file

RE: Warning: Stiffeners on gusset are required due to free edge buckling

Abhisek M — Sat, 04 Mar 2023 11:15:26 GMT

Can you please upload the file here?
It seems from the warning the gusset plates needs some additional check which program is not performing and user needs to take care of that. It will be easier for us to comment better once we see the model.