Rebar Shops 1

[DHKpeWI]

It is my understanding that the concrete contractor will build from the rebar place (shop) drawings and not the structural drawings. We have a project where the rebar shops don't show a lot of information (like spread footing locations and wall elevations) and the rationale is that the contractor will use the rebars shops and the structural drawings for construction.

How have you handled this?

 

[JAE]

The contractor is typically (always?) required to construct the building based upon the contract documents - i.e. your drawings. The shop drawings are tools of the trade, so to speak, that focus down on the minute details of bends, quantities, numbers, bar label marks, etc. which are use ONLY to assist the contractor in meeting the requirements of the contract documents. They do not replace the contract documents.

 

[strucguy]

JAE nailed it. What do your specs say about the level of detail required on your rebar placement drawings? There's no standard in issues like this. Everything has to be communicated thru the language and details in the contract documents.

 

[PUEngineer]

This always seems to be a fight with the rebar detailer no matter how clear the specification requirements are, in that they need to produce rebar placing drawings and not just shop drawings. A good resource would be the ACI detailing manual if you can get a copy.

However, on rebar placing drawings you probably won't find spread footing locations or even wall elevations. Those bits of information aren't really useful for placing rebar, are they? The rebar placing drawings should be stand alone documents that the rebar placer can place all rebar from. And should contain surface clearances, bar spacings, starting and ending locations, etc.

This isn't to say that any formwork or footing locations should come from those documents, that information would be contained in the contract documents or formwork documents, if they are produced. I say as long as the specificatons reference ACI, then the ACI detailing manual would apply as a typical standard of practice.

At least that's my interpretation.

 

[dcarr82775]

I have never seen plan dimensions and actual elevations on rebar shop drawings. I often require that the rebar shops include elevation views of the walls and that the reinforicng layout is clear. In this area a lot of contractors use the shops to tie the steel. They still have to conform to the drawings, but a good set of shops is a lot easier for a guy tying steel than our drawings with all the extra information they don't need.

 

[jgailla]

My limited construction experience as a rodbuster and inspector leads me to believe that the contract plans are typically not used in the field. Shop drawings are used. The GC has a nice clean set of plans in the office, but the guys actually building the thing go off the shops. As an inspector, I was required to go off of the contract drawings for inspection, and you could tell when working out issues with the rodbusters that they had never seen the actual plans.

 

[msquared48]

JAE's comment is exactly why we SEAL and SIGN the contract documents, but only REVIEW FOR COMP{LIANCE and SIGN, but never seal the rebar drawings.

Mike McCann
MMC Engineering

http://mmcengineering.tripod.com

 

[TXStructural]

Rebar shops are not placing drawings, but many placers end up using shops AND the structural CD's. The preferred method is to use placing drawings (as outlined in ACI 301: Placing drawings—... placing drawings showing fabrication dimensions and placement locations of reinforcement and reinforcement supports.) The level of detail required in many cases requires reference to the structural drawings, since we should not necessarily expect rebar suppliers to re-draft every detail, such as grade beam-pilaster intersections.

The references for practice are the CRSI Manual of Standard Practice and CRSI Placing Reinforcing Bars book. The ACI Detaiing Manual is maintained by ACI/CRSI joint technical committee 315, and provides guidance for detailing and development of placing drawings. Also, tolerances are shown in ACI 117, so that reference should be handy.

A note from our sponsor: Keeping details consistent on CD's will greatly improve the economy and quality of the final, constructed structure.

 

[WillisV]

In my experience, if you go to the site you will generally see the rod busters using rebar shops for the layout (if you are lucky enough to see plans anywhere). I have never seen "placing drawings", and finding a set of structural drawings on the site will require a trip to the job trailer.

 

[JedClampett]

I don't care what they build the reinforcing to. They can use the shop drawings, napkin sketches or grunt and point. Our inspectors, however, inspect to the contract drawings and the contractor is expected to adhere to those.

 

[PSUengineer1]

It looks like you are getting a lot of good feedback here. I agree with all of it to this point. Yes, be aware that the rodbusters will only have the shop drawings most of the time. Be sure you tell the GC/CM to dust off the specs and READ THEM!!!! I have checked many rebar shop drawings and I always tend to refer to sections on the CDS.