Concrete Rebar Placement Drawings 3

[strguy11]

Do you require Concrete Rebar Placement Drawings/Shop drawings for every job? If not, when do you make the requirement necessary.

I have a contractor saying he never has had to submit these. Even though this is a relatively simple building concrete wise, we have a number of embeds on the project and required them. I told him he needed to submit them because they were required as part of the specs and drawings, but now he is going to the Owner and Arch saying we are adding un-neccesary costs to the job.

What are your typical practices?

 

[msquared48]

Tell the Owner and Architect that they have added an unnecessary contractor to the job.

This requirement as the project structural engineer is your call, and yours alone. If the requirement is listed in the job specifications, then this is not an extra. Tell the Architect and Owner that this is not an extra and the contractor is just whining because he missed it in the bid. Make him fulfill the contract, and really peruse all requests for payment from this point forward. This guy obviously bid low to get the job, hoping to make the difference on extras. Give him no quarter here.

Mike McCann
MMC Engineering

 

[rowingengineer]

I like the way you think Mike.

When in doubt, just take the next small step.

 

[msquared48]

Thanks for the star - just doing my job.

Mike McCann
MMC Engineering

 

[racookpe1978]

Check his math and re-measure his "as-placed" positions on those embeds very, very carefully.

If he is low-balling/irritated at the work and contract conditions, underneath poured concrete is a GOOD place to hide all of your frustrations.

 

[msquared48]

And, under the circumstnces, if YOU cannot physically verify it, it being anything beyond this point, then the rule is to tear it out and do it again - at HIS cost and to YOUR satisfaction as the owner's representative.

Man, but I'm bitchy tonight!

Mike McCann
MMC Engineering

 

[ChadV]

I worked on a not-to-be-named Caribbean island where the common argument was "we've never had to submit them on anything before" in conjunction with "aren't all the bars are on your drawings, right?" Even the architects tried to convince us they weren't needed. Sometimes we gave in, but on a particularly complicated one we pushed and ended up getting "shop drawings" either hand-drawn or marked up in red pen on blowups of our plans. It wasn't exactly what we expected but it did the job.

 

[dik]

If it's not included in the specifications, included in the drawing notes, or listed in a referenced code of practice, it is likely an extra to contract. Best to review the specs and the drawings prior to giving an answer.

Dik

 

[BigH]

msquared48 - did you get your wife's visa bill today??

 

[hokie66]

I assume this is in the US, and these were always required when I practiced there. In Australia where I now live, reinforcing shop drawings are unheard of. It always amazes me that they get the bars correct, or at least mostly so, by just using bar lists and the structural engineer's drawings.

 

[rowingengineer]

Hokie,
Just for info, I have been specing/getting shop drawings provided for my transfer slabs and columns in Australia. No complains yet, because Genrally the major steel suppliers do shop drawings, just engineers don't want to see them.

When in doubt, just take the next small step.

 

[phuduhudu]

Interesting- In my part of the world I have never heard of shop drawings for rebar. What more info can you get off these than off a proper detailing drawing with a bar bending schedule? I have often wondered why we ask steel fabricators to do shop drawings with all the details on but not concrete contractors.

 

[strguy11]

I appreciate the comments on how to deal with the contractor, but my question was whether everyone usually requires these, or at what level these are normally done?

 

[CTSeng]

It's a judgement call but for me on simple projects with only soil supported footings and/or walls I don't require rebar shop drawings. But for any raised cast-in-place I do require.

 

[jike]

Simple projects like all straight bars, minimal corner bars for footings, frost walls, slab on grade, etc. no shop drawings.

Structural columns, beams, structural slabs, mats, pile caps, caissons, etc require shop drawings.

 

[Zambo]

I agree with phuduhudu that for most jobs a structural engineer's drawing with a bending schedule is all that is required. So generally this would cover pile caps, beams, columns, slabs.

But there will be cases where the contractor has some cast in items which are his selection and sizing. This may include prestressing detailing where the contractor would then have to do shop drawings for the rebar to show how everything fits together. Other cases would be where the contractor's working method may require additional detail to the rebar, e.g making a space to fit a tremie tube through.

I have also come across structural engineer's drawings without bending schedules where it isn't possible for the guy's on site to identify the shape or exact location of the bars. In this case I think it is laziness on the part of the structural engineer, not a need for shop drawings.

 

[DRW75]

I have required and reviewed many shop drawings of rebar. As was said, it depends on the complexity of the design if you think you NEED it. If its a simple foundation, then probably not. But there is always something to be said for reviewing the rebar drawings anyways to make sure that there were no oversights by the rebar supplier (which can happen quite easily - even basic rebar can be pretty complicated). Usually I will do some spot checks to make sure that they have calculated the proper embedment depths, hook lengths, etc... If that stuff looks good, then you tend to get that warm cozy feeling that you're in good hands.

NEVER trust anyone who says they've "never had to submit this before" or "the have never had to do it like this before". This is a very common tactic. And an annoying one I might add.

If it's black and white in the spec, nail them (or use it as leverage against other possible extras).

 

[AHaddad1]

I believe the contractor should do shop drawings for his own protection, because when you to observe the slab reinforcement before the concrete pouring operation and there is something wrong, then he has to fix everything before he is allowed to pour the concrete. This usually will end up costing him more money than simply installing the rebars using a shop drawing.

I have done work all over the world and here is the key points.

1) Design Build Projects can go from the Design Development stage to shop drawings with out going to a final design phase. in other words the design engineer will prepare all the bar placement and bending schedules for the contractor to build. Till today there are some countries where the contractor will bend all the bars in the field and not in a steel fabricator shop.

2) Design and then Build Projects has to go though final design phase before the bidding process starts. The final design phase may not include bar bending and placement schedules in which case the contractor has to provide (again for his own protection, otherwise he is an inexperienced contractor). There are cases where the owner asks for the shop drawings to be included in the final design phase in which case the contractor does not have to prepare shop drawings.

In all cases the bar bending and placement should be done not because it is a requirement but because it is a necessity to save money for the contractor and owner.

The contractor may take the risk if the owner allows it at the same time he has to take the responsibilty of fixing everything that is wrong before pouring any concrete. This usually will end up costing him much much more than a stupid shop drawing.

 

[hokie66]

phuduhudu, Zambo

Bending schedules in the countries where I have worked are never prepared by the structural engineer on building projects. There was a time when they were, maybe 50 years ago, but not now. It is not a matter of laziness, but rather a matter of who is in the best position to prepare the bending schedules, and who is being paid to do it. In my opinion, the supplier of the reinforcing (or his designated detailer) is the appropriate party. Bar bending schedules prepared by the structural engineer and included with the tender documents would in today's environment be useless due to the propensity of architects to change things during construction.

 

[csd72]

hokie66,

here in the UK they still do bending schedules but no steel connections. Seems to me it should be the other way around.

strguy11,

Give them the option. Either they submit the reinforcing drawings to you or they pay you to come out and inspect what they have done. This makes you look helpful and flexible but we really know which option he is going to choose.