3.3.6
Anchorage Installation
The bearing plate and [anchor head] [nut] shall be installed perpendicular
to the tendon, within [0.05] [_____] rad [3] [_____] degrees, and centered
on the tendon without bending of the stressing steel. [Wedges, wedge holes
and tendons shall be free of dirt, grout or other contaminants.]
[Corrosion protection shall be maintained intact at the anchorage and any
damage shall be repaired prior to stressing.]
3.4
STRESSING
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NOTE: The lock-off loads should be a function of
the structure being anchored and tolerable or
anticipated movements for loading changes on the
structure that will cause load changes on the
anchor. Typically, lock-off loads are equal to or
slightly higher than design loads. The last
sentence should only be included when verification
of anchor length is needed prior to installation of
production anchors.
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3.4.1
General Requirements
After the anchor grout [in the bond zone] has reached sufficient strength
in accordance with the Contractor's designthe specified strength, as
verified by grout cube break, the anchors shall be stressed. Prior to
stressing, surfaces upon which the stressing equipment is resting must be
clean and the stressing equipment shall be aligned as nearly with the
center of the hole as possible. An Alignment Load of [10] [ ] percent of
the Design Load shall be applied to the anchor prior to setting dial
gauges. The Contractor shall stress the anchor in accordance with the
anchor manufacturer's recommendation, subject to the approval of the
Contracting Officer. Design and Lock-off loads are given on the drawings.
The Contractor shall determine the lock-off procedure so that the lift-off
results meet the acceptance criteria specified in paragraph Acceptance.
The maximum stress shall never exceed 80 percent of the guaranteed ultimate
strength of anchor steel. The process of stressing the anchors shall be so
conducted that accurate elongation of the anchor steel can at all times be
recorded and compared with the computations submitted to, and accepted by
the Contracting Officer. [Stressing elements of strand anchors shall be
stressed simultaneously.] Safety precautions shall be taken to prevent
workers from being [behind] [or in front of] the stressing equipment during
stressing. Stressing of the anchors shall be performed in a sequence
submitted by the Contractor for review by the Contracting Officer. All
stressing shall be done in the presence of a representative of the
Contracting Officer. At no time during the stressing and testing of an
anchor shall the stressing equipment be disconnected from the temporary
stressing head or anchor. [Each anchor to be performance tested shall be
declared acceptable before proceeding with drilling for other anchors
within the section [type] represented by that anchor.]
3.4.2
Lock-off
After completion of the all required tests, the load shall be returned to
the Alignment Load and the specified Lock-off Load shall be applied to the
anchor. A lift-off test shall be made to verify the load in the anchor
tendon before the tendon is locked-off and the stressing equipment is
SECTION 02490
Page 37
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