Engineering News
NEWS from AMERICAN CONCRETE INSTITUTE (ACI)
Codification of ASTM A1035
MMFX is working closely with ACI on the codification of ASTM A1035. MMFX 2 rebars can be used for up to 100,000 psi as per ACI 318-08 section 3.5.3.3 – deformed reinforcing bars conforming to ASTM A1035 shall be permitted to be used as transverse reinforcement in section 21.6.4, or spiral reinforcement in section 10.9.3.
In the upcoming ACI 318-08 code, the following references are added to the code for using ASTM A1035 reinforcing bars:
- In section 3.5.3.3 – deformed reinforcing bars conforming to ASTM A1035 shall be permitted to be used as transverse reinforcement in section 21.6.4, or spiral reinforcement in section 10.9.3.
- In section 21.1.5 – reinforcement in special moment frames and special structural walls.
- In section 21.1.5.2 – Deformed reinforcement…
The value of fyt used to compute the amount of confinement reinforcement shall not exceed 100,000 psi.
The value of fy or fyt used in design of shear reinforcement shall conform to section 11.4.2. - In section 21.1.5 – Reinforcement in special moment frames and special structural walls
- … The restrictions on the values of fy and fyt apply to all types of transverse reinforcement, including spirals, circular hoops, rectilinear hoops, and cross ties. The lower limit of section 11.4.2 for computing nominal shear strength is intended to limit the width of shear crack. Research results indicate that higher yield strengths can be used effectively as confinement reinforcement as specified in section 21.6.4.4. The only ASTM specification currently available on high-strength reinforcing bars is ASTM A1035, which specifies a minimum yield strength of 100,000 psi.
Many
cities in North America have approved the use of ASTM A1035 for tension up
to 100,000 psi. In particular, elements of confinement,
shear wall and jamb steel, tension piles, pile caps and raft foundations
are structural elements that are dramatically improved by the implementation
of 100 ksi steel. These innovative design changes improve constructability,
construction timing, reduced congestion, labor costs, crane time,
logistics, and
overall cost. MMFX has received approval by San Diego, Long Beach,
Irvine, and Los Angeles, California; Las Vegas-Clark County; Seattle,
Washington; Orlando and Miami, Miami-Dade County, Florida. New
approvals are pending in many other municipalities.
NEWS from AASHTO
An agenda item was passed at this year’s AASHTO subcommittee on bridges and structures meeting to include ASTM A1035 low-carbon, chromium steel reinforcing bars in the interim construction specifications that will be published early 2008.
“When specified in the contract document, deformed, low-carbon, chromium, steel reinforcing bars shall conform to the requirements of ASTM A1035/A1035M.”