High strength bars
High strength bars
(OP)
Does the aci318 specify any upper limit of bars reinforcement ?
The thing is that i have the contractor which is proposing to use steel reinforcement of fy>1000Mpa in some concrete elements ?
The thing is that i think i wont have anymore a ductile.section since concrete will crush ans steel will always be at its elastic phase with that fy which doesnt satisfy the tension controlled criteria
Thanks for the help
The thing is that i have the contractor which is proposing to use steel reinforcement of fy>1000Mpa in some concrete elements ?
The thing is that i think i wont have anymore a ductile.section since concrete will crush ans steel will always be at its elastic phase with that fy which doesnt satisfy the tension controlled criteria
Thanks for the help






RE: High strength bars
RE: High strength bars
RE: High strength bars
It is not prestressing. Apparently the material is being imported from china.and test has been done to validate the fy.
RE: High strength bars
ACI allowed reinforcing bars are currently less than 500MPa I think.
RE: High strength bars
A good structural engineer is often a blessing for others.
RE: High strength bars
700 MPa (100 ksi) is for usage "in lateral support of longitudinal bars, or concrete confinement."
For flexural applications (which the OP appears to be referring) the max value for fy for design calcs is 80 ksi (550 MPa), or 60 ksi (415 MPa) for special seismic systems.
RE: High strength bars
However,these values that ACI is refering to are to be used in design.
But is there any recommendation stating for example that 550MPA bars should not show a fy higher than 20% when tested ?
I dont know if i made myself clear
RE: High strength bars
RE: High strength bars
RE: High strength bars
ACI 318M-14 Section 1.10, provides a procedure for getting the approval of alternate construction materials that not covered by the code at present.
Can it be applicable in your case?
A good structural engineer is often a blessing for others.
RE: High strength bars
RE: High strength bars
Also, the bars you mention most likely do not have sufficient ductility between yield and tensile. In this case, there will be insufficient warning of impending failure. There are a number of other reasons not to use brittle reinforcement but the main reason is that the codes do not work properly unless the materials conform to the required specs.
(I am no longer associated with the reinforcing industry but will continue to try to answer questions when I can.)
RE: High strength bars
I will search in the astm if they give any percentage not to go beyond for a specified fy.
The contractor is saying that he may also usr this type of bars in concrete pipes where no bending is present, just axial forces
RE: High strength bars
Development, shear and other areas would also be a problem.
Basically you would have to go back to first principles logic for all aspects of design and not use ACI code simplifications.
You would also have to test the steel for relaxation (steel creep under tension) and performance in fires.
Also check its ductility and all properties (I mean yourself, do not trust their certificates).
RE: High strength bars
ACI318-14, in its section 20.2.2.5 limits the actual yield strength of the deformed non-prestressed longitudinal reinforcement resisting earthquake-induced moment, in high seismic areas and states that it should not be higher than the design yield strength by more 124Mpa since a higher fy will lead to higher shear and bond stresses at the time of development of yield moments (assuming that a grade of 420Mpa is used).
This is the only limitation that I found regarding this subject.