Strength reduction for Crimped Pipe connection? 3

[EngineerofSteel]

I'm analyzing an existing structure. The engineer used pipe sections for horizontal bracing. The ends of the pipes are crimped flat and bolted to the main structural members.

Is the pipe section reduced in strength? Effectively, it seems to me, the Sx at the flat section is the same as two pieces of flat strap.

I appreciate any insight on this, or any other considerations I might be overlooking.

Thanks, DD

 

[youngstructural]

I would be concerned about the connections... Are they concentric? There have been alot of failures over the years attributed to eccentric connections. See this link for a decent summary of the concern:

http://www.microstran.com.au/lmc_brac_cleat_comp0.htm

About your question proper; there has been alot of research into this field. I'm not very familiar with it personally, but have a coleague who is. I believe there's a good book on the design of these connections out of Europe. I'll make some inquiries around the office for you...

B.Eng (Carleton)
Working in New Zealand, thinking of my snow covered home...

 

[JStephen]

I think the intent is probably that it is a pinned connection laterally, so the reduced section modulus is not a drawback necessarily.

 

[EngineerofSteel]

youngstructural- Yes, the connections are slightly eccentric, already made note of it.

JStephen - I believe you are correct, these members are horizontal only and other loads are transferred by extensive cable bracing.

Thanks!

 

[UcfSE]

I'd follow the AISC or the steel code where you're from, checking local instability , gross area and net area. If they are only crimped at the ends, you don't have to check the crimped section for buckling since buckling occurs in the middle of the member.

 

[EngineerofSteel]

That's it...
Thanks UcfSE, that's the common sense I didn't want to simply accept before I had asked some questions.

I will analyze as pinned and design for max moment at center span.

-DairyDesigner

 

[Tomfh]

Read this:

http://www.steel.org.au/html/news/e_news/eccentric_cleats.htm