Estimating the amount of re-bar???
Estimating the amount of re-bar???
(OP)
Hey all.
How would you approximate the ton of reinforcing in say a footing? I am doing a quick estimate of material quantities (cubic yard of concrete, ton of re-bars, etc.) for a foundation. I have not done a design of the footing and I don't know the loads applied to it, but I did guess the size of the footing. Would there be a way of estimating the ton of re-bar if I don't know the size, number or spacing of re-bar being used?
If I have a 4ft x 4ft x 1.5ft thick footing, could I just use the volume of concrete (24 cu.ft.) and multiply the density of steel (489.6 lbs/cu.ft) to get the total weight of steel required. (24*489.6 = 11,750 lbs of steel required.)
Am I out to lunch on this?
Thanks,
Mark.
How would you approximate the ton of reinforcing in say a footing? I am doing a quick estimate of material quantities (cubic yard of concrete, ton of re-bars, etc.) for a foundation. I have not done a design of the footing and I don't know the loads applied to it, but I did guess the size of the footing. Would there be a way of estimating the ton of re-bar if I don't know the size, number or spacing of re-bar being used?
If I have a 4ft x 4ft x 1.5ft thick footing, could I just use the volume of concrete (24 cu.ft.) and multiply the density of steel (489.6 lbs/cu.ft) to get the total weight of steel required. (24*489.6 = 11,750 lbs of steel required.)
Am I out to lunch on this?
Thanks,
Mark.






RE: Estimating the amount of re-bar???
RE: Estimating the amount of re-bar???
Now, I am going out to lunch!
RE: Estimating the amount of re-bar???
I have worked on projects (Design and Build) where our client (the contractor) has pushed for an early heads up on reinforcement tonnage based on volumes alone. You apply estimates as best you can by looking at published guides and comparing it to previous jobs but it will still being wrong. In once case we even ended up defending a PI claim as the contractor claimed the estimate tonnage didnt match the final as constructed tonnage and we were therefore negligent. Albiet I expect they saw our PI as a way of recouping their losses.
RE: Estimating the amount of re-bar???
RE: Estimating the amount of re-bar???
RE: Estimating the amount of re-bar???
If you need a more acurate number, there are some old DOS programs by CRSI (or even the way too expensive new programs) that will calculate how much steel you need given specific footing properties.
18" thick footing for a 4x4 - you must have some hefty soil bearing capacity.
RE: Estimating the amount of re-bar???
RE: Estimating the amount of re-bar???
RE: Estimating the amount of re-bar???
To get a better estimate for a different type structure, perhaps you can look at records from completed projects similar to yours.
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RE: Estimating the amount of re-bar???
RE: Estimating the amount of re-bar???
RE: Estimating the amount of re-bar???
All great information.
Mark.
RE: Estimating the amount of re-bar???
RE: Estimating the amount of re-bar???
Withour better information I have tended to use 150kg/m3. (I think that is 430 lbs/yd3).
Once I have more idea of the actual members then I fine tune the quantities.
mrpid's approach will underestimate the actual steel weight as it makes no allowance for laps, bobs or the other bits of rebar that are always needed. However this is a simple pad footing so the estimate would not be far wrong in this instance.