Question to EOR from Precast design engineer

[bobharsh]

If you have a minute... please take a look at some architectural precast connection design concepts to STEEL structures.

1.)How would you (EOR) feel about 7/8"Ø holes punched into the the flanges of your beams (see detail)? Would this be a big deal to you? How would you want to coordinate these holes if they are a possibility? There are several other concepts here - feel free to look.

Note: We typically used welded connections for steel structures - In some areas (Big cities in the North) it is not economical to connect by welding due to strict welding requirements and the need for fire watch. We have also been producing pre-glazed precast units which do not like weld spatter...

As a company - we are looking into designing more weld free type connections that allow humoring. Any ideas?? Concrete structures are typically easier to design for than steel structures.

Thanks ~ Bob

 

[bobharsh]

Here is a better sketch of the punched hole connection. Typically we can get away with locating these adjacent to vertical columns. For longer column to column spans the precast panels may require (1) or (2) connections to the "mid span section" of a beam (depending on column to column length).

 

[Celt83]

main thing I would say from the EOR perspective is I'd have real heartburn with those attachments to the bottom flange of any beam that hasn't been specifically detailed with either lateral torsional restraint or to handle the torsion that will be generate on the section. Can you get your attachments at the top of the beam or slab?

Open Source Structural Applications:

https://github.com/buddyd16/Structural-Engineering

 

[structSU10]

If the EOR is OK with the eccentricities on the system, I doubt they would have too much issue with a few drill holes here and there.

 

[JLNJ]

I don't see any holes through flanges in the sketches. That said, the only issue I would have with holes in column flanges would be to make sure the holes are properly clear of the toe of the flange (edge clearance).

On a side note, we recently had a heretofore reputable erector drill two overlapping holes - looked like a sideways figure eight. This was a problem.

"Punched" hole are OK if they are close to an edge where they can be punched. Others would be drilled in the shop or even field drilled, if alignment is an issue.

Field burned would probably not fly with most EOR's (though AISC might allow it under certain conditions).

As others have pointed out, the eccentric-ness of the load path is the biggest concern.

 

[Ballsack]

If the hole sizes or edge distances are beyond the limits in the code, do an analysis (finite element analysis, etc) to determine the effects on beam capacity more accurately. It is similar to castellated beams (where the holes are in the web instead of the flange) and there are plenty of references for analysis.

An example:

https://pdfs.semanticscholar.org/85fc/16ee3dbbd0a0dc0d180c277231eac1646c73.pdf