October 14, 1994

TO: C. C. Ruth/J. E. McMurry

Bridge and Structures Office, 7340

FROM: T. L. Nelson/J. A. Weigel

SUBJECT: Post Tensioning Shop Drawings

For the last few years, Avar Construction Systems, Inc. has been supplying a majority of post tensioning systems for our bridges. Their shop drawings never include the force after anchor set. This for after anchor is required for the following two reasons:

If the measured elongation is not within 7% of the calculated elongation, a force verification lift off is performed. If this force verifications lift off is within -1% of the calculated force after anchor set and .07 fs’, the tendon can be accepted. The approved calculated force after anchor set is required to accept[t the stressed tendon.

Section 6-02.3(26)A of the Standard Specifications requires this calculated force after anchor set (lift-off force).

I request that all designers reviewing post tensioning shop drawings be aware of and enforce this contract requirement.

Thank you very much.

TLN/JAW