Recently when running an epoxy rebar anchor for tension in Hilti I came across a procedure in their design calcs that appear to be pretty ambiguos with the code. When calculating steel resistance of an anchor in tension, Hilti refers to equation D.2 which Nsar = Ase * phi[sub]s[/sub]*f[sub]uta[/sub]*R. The sentence below this in the annex D puts f[sub]uta[/sub] as being equal to 1.9*f[sub]ya[/sub], however Hilti appears to take the f[sub]uta[/sub] from the G30.18 rebar standard. Logically this makes sense to do, but I am curious as to why that decision was made when the code does not explicitly indicate to do that. If I were to run this check by hand, I would not be given any instruction to go find this information and would likely just apply 1.9*f[sub]ya[/sub]. Further, Hilti treats R as 0.7, treating rebar as a brittle steel element. In contrast, Simpson Anchor takes R as 0.8; rebar as a ductile steel element.
The inconsistency behind the design calculations is making me wonder if they are just overly conservative. Perhaps someone here has pondered this in the past.
The inconsistency behind the design calculations is making me wonder if they are just overly conservative. Perhaps someone here has pondered this in the past.
