ASTM615 , yield and tensile strength reinforcing bars

[structural87]

ASTM 615 dealing with steel reinforcement specifications specifies the required yield and tensile strengths (fy and fu respectively) as well as elongations.
If the grade is 60, fy (min)= 420MPa; fu (min) = 630 MPa (fu/fy=1.5).
If the grade is 75, fy(min)=520Mpa;fu (min) = 690 MPa(fu/fy=1.33).
Other non american standards specifies that fu >1.1fy.
Any ideas why the astm has such elevated tensile strengths ?
Thank you.

 

[EdStainless]

It has nothing to do with higher strength, it has to do with the gap between Yield and UTS.
the larger that gap is the more deformation will occur in overload before failure. That gap is the energy absorption when parts are deformed.

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P.E. Metallurgy, Plymouth Tube

 

[structural87]

Yes i totaly agree.
European normes specify the gap to be higher than 1.1 while astm dictates the above.
The thing is, in one of the project, i have the specifications which need to follow the astm but since the gap of 1.33 (for grade 500) can not be achieved, the contractor is proposing to shift to the european normes where the gap is 1.1

 

[EdStainless]

Are you serious? The rest of the world uses rebar with very low ductility?

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P.E. Metallurgy, Plymouth Tube

 

[structural87]

Edstainless,

yes I am not kidding with u. refer to the attached pic. This is according to BS 10080.
3 types of bars are specified. A, B and C.
A for the lowest ductility category
B most commonly used.
C for seismic regions where the ratio tensile over yield should be between 1.15 and 1.35