History of rebar sizes 1

[TidePoolJunkie]

Hi all--just wondering if anyone knows how the sizes of canadian rebar became convention. The US has sizes that are in increments of 1/8" diameters, Europe has sizes that are in even # increments of diameters. Canada has size names that are in increments of 5mm diameters but the actual diameters are slightly different, unlike US and European sizes.

cheers

 

[BAretired]

Prior to going metric, Canada had the same sizes as the US, increments of 1/8" (for bar sizes up to #10). When we adopted the metric system, it seemed more sensible to size the bars to give a particular area rather than diameter, so 10M, 15M, 20M, 25M have areas of 100, 200, 300, 500 mm[sup]2[/sup] respectively.
Edit: Changes in red correcting a typo. Thanks hokie66.

I believe it was done to make calculations easier for the poor, overworked structural engineers.

BA

 

[hokie66]

A bit of an edit, BAretired. I think it is a 15M bar which has an area of 200 mm^2. M20, 300.

https://en.wikipedia.org/wiki/Rebar

 

[robyengIT]

1 - Kyle : attached file not readable

 

[robyengIT]

a bit off-topic

 

[TidePoolJunkie]

Thanks robyeng. Not sure what happened to the attachment. The (now inserted) inline image is the attachment. So actually the even areas was the reason I started looking into it in the first place. I'm just starting to design with canadian rebar for the first time so it piqued my interest. I thought to myself, this is unbelievable, how the the hell did these rebar sizes all turn out with areas in 100 sq mm increments?? Based on the country info in that wiki link, canada is the only country in the world that decided to make rebar sizes based on area. It doesn't have this info on the wiki page but I bet they were the country that was most recently able to 'come up with' a new convention for rebar sizes..starting with a blank slate so to speak. So maybe they thought hey, going by area is the best way to do it, let's do it that way. Anyways, good stuff, thanks for the rebar history zip file. I'll give it a read.

 

[dauwerda]

In the US, once you get to #9, the sizes are no longer even 1/8" increments either. Bars were previously manufacture in both round and square cross sections, so #9, #10, #11, #14, and #18 have diameters that provide areas equal to 1", 1.125", 1.25", 1.5", and 2" square bars respectively . This works out to areas of 1, 1.27, 1.56, 2.25, and 4 in[sup]2[/sup]