Beam Construction Joint
Beam Construction Joint
(OP)
CIP concrete garage repairs. Full column replacement and enlargement at upper 2 levels. Additionally, a beam (62 ft span) being replaced full-depth (by 8 ft long) at column. Contractor wanted a construction joint 2-ft from the enlarged column face to cast the columns and the 2-ft extension prior to repairing the remainder of the beam. I wanted to pocket the column enlargement and cast the beam repair into that pocket - however, the contractor protested. From that, I released repair details which included 2#4 inclined stirrups (single piece per double legged stirrup) across the construction joint. My shear-friction calcs indicated that I needed 2#3 bars - I am using #4 bars because of what is already on-site.
However, if you look at the photo, they provided 2-piece stirrups with a non-standard 90-deg hook around the btm. bars. Needless to say, I was miffed that they didn't contact me to let me know that they were having trouble placing the specified single stirrup piece. So, the million $$ question - do I make them chip it out and chip a new pocket in the recently cast column (or) do I rationalize this somehow?
However, if you look at the photo, they provided 2-piece stirrups with a non-standard 90-deg hook around the btm. bars. Needless to say, I was miffed that they didn't contact me to let me know that they were having trouble placing the specified single stirrup piece. So, the million $$ question - do I make them chip it out and chip a new pocket in the recently cast column (or) do I rationalize this somehow?
"It is imperative Cunth doesn't get his hands on those codes."





RE: Beam Construction Joint
1) the hooks that you mentioned.
2) the inclined shear friction bars appear to be almost parallel to the construction joint, rendering them ineffective.
3) the pour joint surface is pretty rough.
Are you sure that you need the inclined bars? In these situations, I usually find that the top steel alone is sufficient for shear friction.
If the top steel is sufficient for shear friction, I'd just have the beam chipped back until I had a clean surface to pour against. If not, I'd chip back to the column face plus a nominal bearing ledge.
I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.
RE: Beam Construction Joint
3) I know - they used plastic bags to plug up the first cast. Horrible.
The tension bars at both the +/- regions of these beams do not properly resist the code-required loads. Since those top bars are already at or above capacity, there is no net As req/As prov to use as such. Basically, the whole garage hasn't been designed properly, and it is evident by the a level of cracking that does not appear to be solely related to bad construction.
Your last suggestion is what I am leaning to.
"It is imperative Cunth doesn't get his hands on those codes."
RE: Beam Construction Joint
This is where you've got a bit of room to run if you like. You can double dip with bars that are both shear friction reinforcement and flexural steel. Basically, no matter what the flexural demand, you can use 100% of your top steel as flexural reinforcement.
I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.
RE: Beam Construction Joint
I don't follow. Are you taking the double-dipping from this commentary below?
"It is imperative Cunth doesn't get his hands on those codes."
RE: Beam Construction Joint
I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.
RE: Beam Construction Joint
"It is imperative Cunth doesn't get his hands on those codes."
RE: Beam Construction Joint
I would probably just roughen the surface of the incline to get a reasonable magnitude of roughness and go with it. Although, I don't exactly follow about the inclined stirrups that are nearly parallels the joint. It may increase shear in the new beam, but the weak plane is the cold joint. Again, they need to be properly embedded on both sides of the joint, so I'm not sure how that was planned to work with them so nearly vertical.
RE: Beam Construction Joint
I know that the top bars are developed into the column for sure. I measured them prior to the column full-section repair. The other direction, I do not know as we have no existing drawings.
They are not "nearly parallel" - the photo is a bit misleading in that regard. I have the angle I need. Please read my initial response to Kootk. The whole issue is with the contractor's (bad) decision to change by single piece stirrup to 2-pieces.
I ended up leaving the inclined stirrups as is, roughened the surface to CSP#6, and called it a (frustrating) day.
"It is imperative Cunth doesn't get his hands on those codes."
RE: Beam Construction Joint
RE: Beam Construction Joint
These guys aren't horrible; I am disappointing they deviated from my details without consulting me.
"It is imperative Cunth doesn't get his hands on those codes."
RE: Beam Construction Joint