spiral (helix) metric reinforcement 3

[ILoaThePats]

I tried searching for his but did not find anything. I am performing a conversion of a design from metric to english/imperial and I cannot find anything to explicitly tell me the bar size of spiral/helical reinforcement in a cylindrical footing. The callout is as follows:

4-N16 vertical
R6 helix at 300 pitch

So there are four vertical 16mm (#5) bars and spiral reinforcement at 300mm (1ft) pitch. I suspect that the "N" on N16 refers to the type of steel. I am cannot determine the bar size of the helix however. My assumption is that it is 6mm diameter bar (in which case I would obviously use #3 bar in the US since that is the ACI minimum), but I can't confirm this. I do not think that the "R" could stand for "radius" because a 6mm radius bar converts roughly to a #4 bar which seems quite high for #5 longitudinal. It would also be a tight bend for #4 bars because the overall diameter of the pile is 1'-6".

If anyone can enlighten me on any of these matters I would be VERY appreciative.

Thanks.

 

[csd72]

Is this designed in Australia?

If so then the N is Normal ductility 500MPa reinforcing bar (diameter may be slightly less than number given) and the R is a mild steel round member 6mm diameter and could be only 250MPa.

 

[ILoaThePats]

Yes it is designed in Australia. That is about what I suspected, thank you.

Since it seems you are familiar with Australian design practices, I hope you can clear up a couple other things. The anchor bolts for this structure are M12 Gr.4.6/S H.D. bolts. In some cases this can refer to bent anchor bolts, in others it can refer to threaded rod, and in others it can refer to cap screws. I know what M12 gr.4.6/S means, but what does H.D. bolts refer to? I am not sure if it refers to the actual bolt (such as being a Heavy Hex bolt) or if it is how the part is labelled for purposes of the drawing itself.

Also, what is a "Cog 100 Bolt"?

Thanks

 

[csd72]

I believe that the HD stands for either holding down bolts or hot dipped (galvanised) bolts.

The cog 100 bolt refers to the hook which is 100mm long horizontally.

 

[rscassar]

H.D in the context which you have written in Australia generally means Holding Down. The general convention in my experience is to designate all bolts including holding down bolts as hot-dipped galvanized unless noted otherwise.

Cog 100 means what csd suggested. I would have just said "100 COG" or even dimensioned the cog on the section.

 

[ILoaThePats]

Thanks for the input. I found the bolts explicitly referenced as "hold down" bolts in another drawing so I'm sure that what it is.

Cog is an odd word on a drawing in the states so I am going to change that to '4 in. hook' instead of 'Cog 100 Bolt'

While we're at it what does the abbreviation c/crs mean? It refers to a square bolt layout and I'm changing it to "o.c." but I'm still curious about the expansion of c/crs.

 

[hokie66]

Stealing our Australian designs to use in the US? That's why we make the abbreviations hard to understand.

 

[ILoaThePats]

Sister companies so it backfired this time!

 

[apsix]

'c/crs' appears to be an amalgamation of 2 different (and usually separate) conventions;
1. c/c; meaning centre to centre
2. crs; abbreviation of centres

 

[ILoaThePats]

Good answers all.

Does anyone know what grade of steel CHS sections typically use? I assume it's similar to HSS (42ksi yield, 58 ksi tensile) but there are some CHS sections here that are smaller than anything available in HSS so I was going to use Pipe but Pipe is different than HSS (yield 35 ksi, tensile 60 ksi) so I want to make sure the pipe will work.

 

[gobsmacked]

In UK, R6 has been used for Round mild steel, That is, not deformed, and yield stress around 250 MPa. R just means round, undeformed.

 

[hokie66]

CHS, circular hollow section. AS1163 250 or 350 MPa commonly used.

 

[rscassar]

Are you designing the steelwork for an Australian project and to Australian Standards. If so, the readily available tubular sections in Australia can be found at

http://www.edconsteel.com.au/pdfs/information/coldformed_sections.pdf

I have seen higher grades called up, say a 450MPa section which is non-tyical grade but it will have some lead time and greater costs associated.

 

[ILoaThePats]

The structures are modular and they were designed in Australia. I am converting them to imperial for fabrication in the U.S. It's interesting that the common grade for CHS in Australia is 350 MPa since the standard for round HSS here is 290 MPa (42 ksi).

Thanks for the available sections brochure, this is what I've been looking for!

 

[csd72]

The notes should state which grade of CHS is specified as it does vary depending on if it is hot or colled rolled.

 

[apsix]

I understand that all HS in Australia are cold rolled.
Using hot rolled should be conservative, for identical grades.

 

[hokie66]

Tubes aren't hot rolled in their final form. They are cold formed from hot rolled plate and resistance welded.

 

[apsix]

That's true for Australia, but in Europe both Cold Formed and Hot Finished are available.
I'm guessing it could be true for the US also.
Using Hot Finished instead of Cold Formed isn't a problem, the reverse is (assuming identical grades).

 

[ILoaThePats]

Another question: I have two types of wire mesh reinforcement specified in different places: F82 and SL82. Both are 7.6mm x 200mm in transverse and longitudinal directions. What is the difference between the two? Is one deformed bars and the other round bars?

 

[csd72]

F82 is the old designation and SL82 is the new. From memory I believe it also changed from 460 to 500MPa and from 8mm to 7.6mm diameter. Both are deformed bars.

http://www.onesteel.com/images/db_images/productspecs/Designation_Bar_Mesh0504.pdf

Hope this helps.