3D BIM Rebar Shop Drawings
Rebar Fabrication
Rebar Shop drawings - Important to Understanding Labor Force

Rebar Shop drawings - Important to Understanding Labor Force

This is a very important subject.

Most detailers don’t pay enough attention to the installation part of the job.

They forget the purpose of the Rebar Shop Drawings.

We are producing Rebar Shop Drawings, which are Rebar Placement drawings. Labors will use these drawings to install rebar. 

Our aim should be making easy and understandable drawings for Labors, Not getting an “approved “ stamp from the engineer.

I am going to try to explain, how labor uses the shop drawings. I believe this will help you guys understand a little more about how a real rebar shop drawings should be look like.

First, you should put yourself in their position to understand their situation.

Let's say, We are a foreman for this project and  supervisor told us to build this column footing F5.0 shown in structural drawings below,




First, we lay-out the location of the footing, so we need to mark Column Line 3 and Column Line B on the ground from given points by the surveyor.

Licensed surveyor comes and gives a point for a reference, and provides a drawing showing the location of given points. The surveyor point could be written on a piece of wood or wood with flag and usually, it has a note saying how far away from the specific point.




They call these surveyor stakes. The picture does not belong to this project, but you can see the surveyor point on the top of white short wood pieces and wood stakes at each side giving the distance from that point.  You need at least two given points two get a straight line.

Let's say these stakes located at 20’ and 30’ away from column line 2 and right on the column line, B.  Distances should be shown on a surveyor plan and on the stake itself.



 


So Now we know stake  20’ away from column line 2, and column line 3 13’-6” away from Column line 2. So Column line 3  20’+13’-6” = 33’-6” away from surveyor stake. We pull out a tape measure and measure 33’-6” to locate column line 3, but we need one more reference point to make sure, we are right on the column line B  We use 30’ stake, it is called set back line and 20’ stake to get a straight line.

We need to use a surveyor machine to get a straight line from the set back point to Column line 3. This is another subject.

I am just trying to explain how hard to transfer dimensions from drawing to actual ground.

Let’s move on,

after locating Column Line 3/B intersection, we need to move 5 5/8” more to locate center line of column





We have the center point of the F5 footing,

Now we need the found size of the F5.0

Footing schedule showing 5’x5’ square and 18” deep





Once we mark out sidelines of the footing on the ground, we ready to set the rebar.

Now we look at the rebar shop drawing,





We locate the F5.0 footing on rebar shop drawing and we need to see section B/R03,

Now we go to section B/R03.


This section detail is the most common way, you will see, and probably ok for most of the detailers.



It is showing me 7#5 Bottom each way, that's all,  but It doesn’t show me the most important pieces of information,

-  I need to cut the rebar but it doesn't show the  length of the rebar,

- I need to set the rebar in place but it doesn't show clearance for the concrete,

- Als I need the hook sizes, but there is no Bar Mark to find out the size of the hook, 

I keep looking in the shop drawing, hoping to see if there is another detail, and I found F5.0 footing on page R03A and section is C/R03-A. I know there is no other F5.0 in these plans so, I am guessing detailer made an error and instead of calling section C/R03A he called B/R03.




Maybe that was a simple mistake, because of that mistake foreman lost 5- 10 minutes to find correct detail. And imagine if there are 4 more labors waiting directions from foreman . 4 x 10 min total lost time is 40 minutes because of a simple mistake.

Let's move on,

Contractors pay extra money to rebar fabricators to get rebar pre-bend. Fabricator bends the rebar using automated machines and bundles them and tags them. Fabricator uses the bar list provided from the rebar detailer to proceed to bend and cutting.




When we look into Tag,





Tag shows the shape of the rebar and length of each leg, Bar Mark and size # of the rebar.

 

Now let's go back to being a foreman,

Let's say we already have all the rebar delivered at the job site.  And we need to find rebar for F5.0 footing.

 



So we need to find C514 bar marked rebar from the big pile of rebar. To be able to understand what the Rebar look like,  we need to look at the bending schedule. 

Where is the bending schedule?

Some detailers add the bending schedule to Last page or where ever he wants.

I am looking at page R03 and this page doesn't have Bending Schedule than we find a bending schedule and that one doesn't have C514.

4 guys waiting and you are the foremen, you have to make the decision. 

It is very important to have a bending schedule on every page for the rebar shown in that page.

This makes a huge difference between detailers. 

Let's move on,

Let's say finally we found the bending schedule and locate C514.

We see there are 14 of them with size 5 and  shape type 2 and length of middle section B is 4’-6”



And we tell labor, to  “ find me 14  C514 #5 bar U shape 4’-6” long at the middle.

Now Labor has all the information to find you C514 from a big pile of rebar. Maybe He can't find the tag for C514 just by looking and but he knows the length and size of the rebar he is looking. He just needs a tag to verify. He measures the mid part to make sure and checks the tag. 

You should learn about "Intelligent Bar marks" , that helps to find rebar a lot quicker . I will post an article you should read.

Once he found 14   C514 ,

how do you install them, how high from grade?

How do you support the rebar?

Rebar Shop drawings don’t have the information,




On rebar chairs or on concrete bricks.

Most of the time on grade, they use concrete bricks. Not chairs because chairs may sink a lot easier than concrete bricks. The well-compacted grade helps a lot. If the ground has mud, even concrete bricks sink.

It could be very nice to show concrete bricks under the rebar.

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