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Wide Beam Connections

Wide Beam Connections

Wide Beam Connections

(OP)
What type of things I need to consider to frame a 4' wide beam into a 2'square column?  Also where would I look to find information on this type of connection?

RE: Wide Beam Connections

I am assuming this is concrete?
I would look at the shear at the face of the column using b=24" instead of b=48"

RE: Wide Beam Connections

(OP)
Yes it is PT concrete Garage.

RE: Wide Beam Connections

Might want to consider tapering your column head to meet the extent of the beam, extending the tapered section beyond the column too, and again, check the shear at the column.  This is the same concept as the old tapered shearheads.

Mike McCann
MMC Engineering

RE: Wide Beam Connections

Add a 4' wide corbel to the face of the column.

RE: Wide Beam Connections

I basically disagree with all the other advice you have been given.  A beam wider than the column is no different than a band beam or flat slab drop panel.  You need to check beam shear on the full width of the beam (not the column width), and punching shear on the code specified perimeter, with due allowance for unbalanced moment.

RE: Wide Beam Connections

I would increase your column width to match your beam width. If your beam needs to be that wide, I don't think anybody would question seeing a rectangular column as wide as the beam. Along the same lines, if you beam is that large and the connection will be fixed, can your column support the end moment?

Had I not known anything about your job and I saw a 4' wide beam framing into a 2' wide column, that would definitely stand out to me.

 

RE: Wide Beam Connections

a wider beam than column is not uncommon and would not stand out.  i know of at least one MLB stadium and one NFL stadium designed this way at the main concourse and these are massive structures.  

Office buildings also use a similar system using 'shallow wide' beams that are typically 6 ft wide and 18" deep.

A narrower beam than column is a detail to stay away from based purely on framing costs.

RE: Wide Beam Connections

hokie66's advice is right on the money.

RE: Wide Beam Connections

hokie...

OK...  PT construction, banded tendon layouts with wide beam strips and small columns.  

I thought the standard way to handle the wide PT beam strip and small column scenario was to provide drop caps at the column, boxed or tapered, whatever, when needed for shear in order to limit and/or optimize the design depth of the PT slab.  

Am I missing something here?  sadeyes

Mike McCann
MMC Engineering

RE: Wide Beam Connections

Mike,

My answer applies to wide beam to column connections.  Banded tendon layouts like you use in the US for flat slabs is not something I agree with, but not relevant to this thread.

RE: Wide Beam Connections

Hokie:

Please bear with me here... peace

I don't understand why not.  Aweb11 is talking PT here, and banded or not, the same shear distribution problems can exist.  Banded tendon strips are, essentially, wide beams in the PT slab.  

The drop panel just increases the allowable punching shear from the column, allowing more load in a smaller area to get be sucked into the column.  This shear capacity can even be increased further with special studded metal strap embeds criss-crossing the column centerline.  

Mike McCann
MMC Engineering

RE: Wide Beam Connections

Mike,

I am not sure we disagree on much here, but the OP was asking about a 4' wide beam going over a 2' square column.  Hardly a small column.  I didn't agree with some advice he was given, so said so.  SEIT's advice was wrong, and I thought yours and civilperson's advices were off point.  After my comment, and perhaps before he read it, tngolfer also gave poor advice.  For the record, Galambos and apsix  understand what I wrote and agree.

RE: Wide Beam Connections

The last part of the link posted by Galambos is exactly what I am talking about here.  If you agree with that, and it sounds like you do, then I guess we agree, except for the banded tendon concept.  ponder

Cheers.

 

Mike McCann
MMC Engineering

RE: Wide Beam Connections

Yes, the plan called "shallow-wide long span design" is what I was talking about.  I call the continuous thickenings band beams.  Sometimes only the band is tensioned, sometimes only the slab, but usually both or neither.  The OP said his structure was posttensioned, but it doesn't matter.  This is an efficient system whether conventionally reinforced or post-tensioned.

RE: Wide Beam Connections

I agree with hokie66--it is helpful to think about HOW this beam will fail in shear.  It will NOT fail across just a two foot width, but rather it will either fail across a four foot width in one way shear, or the column will punch through the beam.

DaveAtkins

RE: Wide Beam Connections

I wasn't thinking in lines of a slab beam. I agree with hokie on that.

I had pictured a beam of roughly the same depth as the width or even deeper than its width. In this case, I am sticking with my bigger column recommendation unless you can show the column can handle the moment. I still think if you need a beam that big your column may not be able to handle the fixed end moments from your beam.  

RE: Wide Beam Connections

tngolfer,

That is too simple.  The moments distribute in proportion to the stiffness, so a bigger column will attract more moment.  The column doesnt have to "fix" the beam, it just has to take its share of the moment.  Take the case of a big concrete beam supported on a relatively tiny steel column.  Pinned connection, but the beam can still work.   

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