Wide-Flange Brace to Wide-Flange Column Connect. Design... 4

[jochav5280]

I am a new engineer and have found it fairly difficult to find a good connection design resource (unfortunately, they don't seem to teach but the basics in Undergrad level courses). Currently, I need to design a Wide-Flange (W10x49) brace that comes into a Wide-Flange (W10x30) column at a steep 13 degree angle relative to the vertical position. I've been advised by my counterparts to just make the connection "stout" and not to worry about it; but I don't think this is the responsible way to work. Any advise on what resources I might be able to use in this situation and or what limit states as per the AISC spec I need to check? Thank you!!!

 

[youngstructural]

I hope we can all agree on three points:

1. No engineer, no matter how inteligent or experienced can detail any connection without fully understanding, and giving consideration to, the strength, stiffness and constructibility of that detail.

2. An engineer must, no exceptions, have designed a connection type thoroughly, several times, prior to taking any simplifying steps in their design process.

3. Our peers, and particularly their advice, are normally focused on a particular point or set of points. They will have missed things, and our comments are normally added/required because we see something else that should be given thought.

I echo frv's comments, and spats alike this time: We don't know everything, and design must be the focus of our efforts. Everything else is engineering judgement.

I'm going to get back to work,
Regards,

YS

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

 

[hokie66]

This argument has me confused: which "counterparts" gave the advice to "dance"?

 

[hokie66]

Sorry, I see, the counterparts were in the OP.

 

[csd72]

Whats wrong with dancing?

 

[DWHA]

cds72

If you have seen me dance, you would know what is wrong with dancing.

 

[JLNJ]

First you need to sketch yourself some sort of geometrical arrangement for the connection which is sensible. Such a steep brace-to-column angle makes for a long ugly connection. Maybe you can introduce some eccentricity to make things go together easier. You then need to design the parts for the eccentricity, of course. If this is not at the base plate then you need to keep in ming that the force needs to flow through the connection to other members on its way to the foundation.

I am surprised to see a 49#/ft brace being connection to a column which is just 30#/ft. This seems very odd to me.

If you want suggestions or specifics you might try posting a sketch.

 

[hokie66]

JLNJ,

He did post a sketch on 21 April, although it was not as steep as the quoted 13 degrees. I gave him a suggestion on 22 April, but after that the thread has mostly been about philosophy.

 

[kslee1000]

Jochav5280:

At the lower connection as your sketch indicated, since the brace is concentrical with the column, and so close to the column base, I will focus my design on the brace-column connection for vertical shear, and the column-base plate for horizontal shear. You may do a quick check on moments on the column (caused by the offsets), resolving the net moment into couples on the column flanges, then add the resulting stresses to column stresses from other sources, and check the results.
Looks like the original designer has already figured that the inner flange will carry a significant amount of load, so it is aligned on/closer to the center line of the concrete pedestal (good thinking).

 

[kslee1000]

Follow up on my previous suggestion:
For practical reason, I prefer to see the inner flange taking all the compression/tension from the brace, and design for it (column/anchorage/foundation).