SI vs. Metric vs. US Reinforcing Call-outs 3

[BorisKoratPE]

I have a drawing showing European rebar, calling out the rebar as "Ø25" that refers to 25 mm diameter reinforcing. I have another drawing calling it out as "#25" that an American like myself would verbally identify as "number twenty-five rebar" knowing that the #25 stands for a 25 mm rebar as well.

Which is correct? That is, what is the most common, proper practice for reinforcing? Is it a diameter sign or a number sign? Thanks for any assistance!

 

[Bill002]

Good question. As an American I haven't seen drawings in metric much but am actually working on an international project right now. I am not certain but I have also seen it called #25M or 25M.

 

[Teguci]

I think #25 will suffice in just about all cases. If the contractor assumes an American system, he will have an impossible time finding a #25 (I've seen a max #22 by Dwyidag).

Of course, as a fellow American (the "real" kind-smile), the correct terminology would be #8.

 

[BorisKoratPE]

OK, thanks for the input.

I should clarify, while I am working in the USA, this is a project in a European country to be built by Europeans. And all my calcs are in metric. What's the most common practice in Europe and if anyone can point me to a definative resource (I haven't found one on the web, but that doesn't mean it's not there) I would be most grateful.

 

[Guest262653]

I work in Europe and it is common practice here to reference explicitly the rebar diameter, so "4Ø25" would be used for 4 rebars Ø25 and "Ø25//0.25" would be used for Ø25 rebar evenly spaced 0.25m.

In some countries some additional information on the type of reinforcing steel (ductility class mostly) is also included in each rebar reference, but you'll need to check it individually.

 

[TXStructural]

Reinforcement in the US is NEVER called out using metric designations in engineering documents/CD's. In fact, US-produced bar will transition back to US customary bar markings over the next few years. The original move to "soft metric" was a kludge to meet US government mandates for a shift to metric/SI. Since the move to SI has failed, CRSI will be dropping reference to the soft metric sizing in its publications, with the blessing of the US agencies that compelled the original change. US sizes where never actual metric sizing, simply re-marked customary sizes.

For projects to be built in Europe, all work should be completed using the sizes which will be available and used. In general, these are true metric sizes.

http://shop.bsigroup.com/ProductDetail/?pid=000000000030016684

 

[Ussuri]

UK practice is to specify the type and size so high yield steel (code H to BS8666), 25mm in diameter is called off as "H25".

So if you had 100 of them it would be 100H25. If these were called off as barmark 01 on the schedule and were spaced at 150mm centres then you have 100H25-01-150. There are then commonly instructions for placement which follow (Top, bottom, each face) and (staggered, alternating etc) 100H25-01-150-EF ALT

 

[BorisKoratPE]

TXStructural: this is very interesting information. Wow! The BS is charging 196 pounds for a 74-page document! Man, that makes the AISC look like a cheap lemonade stand...

Ussuri: That is also interesting, useful information. My own opinion is that I would try to avoid different grades of rebar on a contract drawing unless I had total confidence in the construction contractor's paying attention to the drawings. At any rate, 100H25-01-150EF ALT translates, for my non-UK project, to Ø25 @ 150 EF with a note at the beginning of my plan set stating the grade of rebar, etc.

 

[BorisKoratPE]

Oh, one more thing. Has anyone using the diameter symbol run into trouble contractually? That is, does a "Ø25" call-out signify that the diameter of that particular rebar "shall" be 25 mm? Or, if, in my plan notes/specs, I cite the appropriate standard - like ASTM A615M or GHOST this, BS that, etc. - will it be assumed that there's a tolerance in rebar diameter? This is a lawyer's question and I would like to be able to provide an engineered answer... Thanks again to anyone who chimes in!

 

[Ussuri]

Personally I haven't seen a reinforcement drawing which uses the diameter symbol, but I have maybe led a sheltered life.

There is a tolerance on the rebar which is usually specified in the relevant standard. I dont have the BS EN that TXstructural linked to, but I do have the BS for example (BS4449). The standards include the tolerance range. In 4449 the tolerance is applied to the mass per metre.

"The permissible deviation from nominal mass per metre shall be not more than ±4.5 % on nominal
diameters greater than 8 mm, and ±6.0 % on nominal diameters less than or equal to 8 mm"

Im sure you could look into it and find other tolerances. It will also likely be different for other countries. It would probably be listed in the eurocode for concrete somewhere in the references.

 

[dik]

In Canada, the bar would be called out as a 25M bar... we have been using SI units for a couple of decades...

Dik