ML17249A910

Revised Pages 4,6 & I-2,Table 3 & Figure 1-A for Evaluation of Prestressed Tendon Forces.

ML17249A910
Person / Time
Site:	Ginna
Issue date:	04/11/1980
From:	GILBERT/COMMONWEALTH, INC. (FORMERLY GILBERT ASSOCIAT
To:
Shared Package
ML17249A908	List: ML17249A907 ML17249A910
References
GAI-2074, NUDOCS 8005210501
Download: ML17249A910 (12)

Text

GAI REPORT NO. 2074 EVALUATION OF PRESTRESSED TENDON FORCES FOR ROBERT E. GINNA NUCLEAR POWER STATION NOVEHBER 20, 1979 Revision I 4-11-80 GILBERT ASSOCIATES, INC.

READING) PENNSYLVANIA Qbert /Commonwealth

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2) Concrete Shrinka e For the Ginna site region, the Hean Daily Relative Humidity is in the 70/ to 80% range. Therefore, from Table 1 of Reference 5, the 40 year shrinkage strain is

-6 100 x 10 in/in. For purposes of plotting on a log-time (log t) scale, shrinkage is taken to start 1. hour v

(0.00011 yr.) after the date corresponding to the average date of containment wall concrete placement. The containment wall construction and stressing dates are given in Figure 2. The shrinkage strain varies linearly

-6 with log t from zero at t = 0.00011 yr. to 100 x 10 in/in at t = 41.4 years (40 years after initial stressing) and K

is shown in Figure 3.-

Only the containment shrinkage which occurs after initial stressing (t = 1.41 years) influences the loss of tendon force. Based on the assumed shrinkage strain variation, a strain of 78 x 10 -6 in/in at t = 1.41 years is calculated. The tendon force loss at t = 41.4 years is predicted to be:

-6 -6 (100 x 10 in/in - 78 x 10 in/in) (29 x 10 6

psi)

. 2 (4.42 in ) = 2.8 kips which is shown in Figure 3.

A variation of +20% in the predicted values is allowed by Reference 5:

The recommended specific creep formula from Appendix A of Reference 5 is:

s c =

Ae 1 - e o + B log 10 (t/to )

f c Rbcrt ICeamewealth Rev1eed 4-11-80

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0.45 and 0.34 for the"5000 psi concrete used in the Ginna containment. The specific creep curves in Appendix C of Reference 6 were used in the calculations.

From Figure 2, the average age of the containment wall at time'f initial stressing was 515 days 'oncrete (1.41 years). A specific creep curve for a concrete age 515 days was obta'ined by extrapolating from the curves in Appendix C of Reference 6. Based on this extrapolated curve, the concrete in the containment wall is predicted to have a 1 year specific creep of 0.08 x

-6 10 in/in/psi and a 40 year specific creep of 0.23 x

-6 10 .

in/in/psi., The corresponding losses of tendon force are:

At 1 ear after initial stressin (t = 2.4)

-6 6 (0.08 x 10 in/in/psi) (628 psi) (29 x 10 psi)

(4.42 in ) = (0.08 x 10 ) (80497 x 10 ) = 6.4 kips At 40 ears after initial stressin (t = 41.4)

(0.23 x 10 ) (80497 x 10 ) = 18.5 kips The creep loss is zero at t = 1.41 years after concrete placement and varies with log t as shown in Figure 3. A variation of +25/ and -15% in the predicted value is allowed by Reference 5.

4.3 QUESTION

Was there a chemical analysis of the groundwater at the site?

RESPONSE: Not to our knowledge. Corrosion protection for the anchor was provided by grouting. This method has been successfully used on a number of projects. See References 7 and 8.

Qbert ICommonwegtth Revised 4-11-80

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TABLE 3 TEN YEAR LIFT-OFF FORCE EST TE FORCE LAST LAST PREDICTED TENDON FIGURE TEST FORCE 'EST NUNBER AMBER (ki s) (Year) (ki s) REHARKS 53 4-1 625 8 621 All predicted forces are based on the Base Value predicted slope through last test data unless noted otherwise.

133 4-2 ,630 626 45 4-3 637 634 4-4 632 627 36 4-7 632 679(627) Based on predicted slope thru 3 year test data (based on 8 year test data).

95 4-13 615 611 142 4-18 612 607 4-24 612 655 (607) Based on predicted slope thru 3 year test data (based on predicted slope thru 8 year test data).

84 4-30 588 584 126 4-31 687 683 160 4-33 612 607 76 4-35 605 602 117 4-42 663 658 110 4-37 657 653 60 4-19 647 621 63 4-14 647 3 630 150 4-40 658 3 640 159 4-10 673 650 51 4-12 665 636 83 4-11 653 624 100 4-16 627 610(575) Based on actual slope thru 1 and 3 year test data (based on predicted slope thru 3 year test data).

132 4-25 653 6 mo. 614 631 Average Lift Off Force in 22 Tendons teated (estimated) nr vi srd 4-11-80 TASLE 3

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a FIGURE 1-A TENDON STRESSING SE UENCE Jack /tl Jack ft2 Jack 83 Jack /I4 13 53 93 133 149 25 69 105 1 45 81 127 21 57 101 137 17 65 97 145 9 61 89 141 5 49 85 129 157 44 77 121 153 26 73 108 151 '27 71 107 185

'139 36 75 79 ill 128 43 3 47 85 125 7 51 87 131 11 55 91 135 15 59 95 139 19 63 99 143 23 67 103 147 24 68 104 148 22 66 102 146 20 64 100 144 18 62 98 142 16 60 96 140 14 58 94 128 12 56 92 136 10 54 90 134 8 52 88 132 6 50 86 130 4 48 84 123 2 46 82 126 160 41 ,

80 124 158 42 78 122 156 . 40 76 112 154 30 74 110 152 28 72 109 150 29 70 106 32 31 113 117 33 37 114 118 34 38 115 119 35 39 116 120

= Retensioned at 1000 hours0.0116 days <br />0.278 hours <br />0.00165 weeks <br />3.805e-4 months <br />".

FIGURE l-A Revised 4-11-80 TENDON STRESSING SEQUENCE

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The tendons were also overstressed to approximately 6% above the force required to produce lift-off, and the tendon elongations recorded. The results are presented in Table I-2. The elongations ranged from 3/16 inch to ll/16 inch, and the corresponding tendon force increases ranged from 8.9 to 51 kips.

The average tendon force increase was 33.7 kips, and the average elongation was 8/16 inch. The predicted elongation for a straight tendon under the 33.7 kip force ~s 6/16 inch. Therefore, the tendon elongations appear to be reasonable, and no abnormal tendon behavior is indicated. Differences in elongations (for approximately the same tendon force increase) are attributed to (1) inaccuracy in determining the point of lift-off, which could be significant for the relatively small tendon force increment, and (2) variations in the friction at each tendon.

The retest indicated higher values than the 8 year tests and general agreement with the slopes of the predicted curves. Where several previous tests are available, Figures 4-4, 4-7, 4-24, the retest value appears to be in line with other earlier tests. Of the 22 tendons, only tendons 51 and 63, Figures 4-12 and 4-14, show greater slopes than predicted. =The results would indicate that many of the 8 year test values were in error.

The average force in the tested tendons was found to be 634 kips.

The predicted average force was 631 kips. The average force based on the technical specification requirement that the tendon stress be at least 144,000 psi is 636 kips. The technical specification also allows for 5% broken wires. If no wires are broken and the allowance were applied to the stress, the minimum required force per tendon would be 604 kips.

Qbett /Commonwealth I-2 Revised 4-11-80

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