ACI-349 Approval for HSL-3 Heavy-Duty Expansion Anchor

Report WC 11-02 Hilti HSL-3 Compliance September 30, 2011
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3.5 Question on measurement of ductility of the HSL-3 anchor steel.
ACI 355.2-01 does not contain criteria for establishing the ductility of
mechanical anchor steel. ACI 318-02 (Section D.1 Definitions) define it as,
“ductile steel element—An element with a tensile test elongation of at least 14
percent and reduction in area of at least 30 percent. A steel element meeting
the requirements of ASTM A 307 shall be considered ductile.”
Resolution: AC193 has incorporated a method for determination of anchor
steel element ductility.
4.3.9 Classification of Anchor Steel as Ductile or Brittle—Elongation and reduction
of area shall be determined according to a recognized standard and reported on the
data sheet (Chapter 11). If the elongation is at least 14 percent and the reduction of
area is at least 30 percent, the anchor shall be considered to meet the ductile steel
requirements. If the ductility and reduction of area cannot be determined, the anchor
shall be reported as brittle in the report.
While ACI 355.2-01 does not specify how ductility shall be determined or
performed, testing of steel elements in the USA typically uses ASTM F 606. As
explained by Eligehausen and Asmus in the submittal to ICC-ES, the
elongation is measured over a gage length of 4d. In Europe, where the ductility
testing was performed on the HSL-3 anchor, the elongation is measured
according to EN 10002 and ISO 898, using a gage length of 5d. The elongation
is measured after rupture of the steel, and is referred to as rupture elongation.
Since the measured elongation contains a small plastic deformation due to
contraction of the steel after passing the peak load, the contraction is limited to
a small length. Under ISO 898, a minimum 12% elongation is required with a
gage length if 5d, which related to a 14% elongation under ASTM F 606.
Elongation testing performed in accordance with EN 10002 and ISO 898 was
submitted, reviewed, and accepted by ICC-ES. The data demonstrated the
actual rupture elongation was even greater than required as a ductile steel
element.
Therefore the elongation requirement is met. Similarly, the measured
reduction of area was greater than 30%. In conclusion, the HSL-3 anchor steel
meets the AC193 requirement of “ductility”.