ML17249A910
| ML17249A910 | |
| Person / Time | |
|---|---|
| Site: | Ginna  |
| Issue date: | 04/11/1980 |
| From: | GILBERT/COMMONWEALTH, INC. (FORMERLY GILBERT ASSOCIAT |
| To: | |
| Shared Package | |
| ML17249A908 | List: |
| 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
0 P,
a
'~h
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 K
at t = 41.4 years (40 years after initial stressing) and 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
-6 variation, a strain of 78 x 10 in/in at t = 1.41 years is calculated.
The tendon force loss at t = 41.4 years is predicted to be:
-6
-6 6
(100 x 10 in/in - 78 x 10 in/in) (29 x 10 psi)
(4.42 in ) = 2.8 kips 2
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= Ae c
f c
1 -
e o
+
B log (t/t )
10 o
Rbcrt ICeamewealth Rev1eed 4-11-80
1 vJ' C
E
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
'oncrete at time'f initial stressing was 515 days (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)
(0.08 x 10 in/in/psi) (628 psi)
(29 x 10 psi)
-6 6
(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
~ >
1
'll 9
TABLE 3 TEN YEAR LIFT-OFF FORCE EST TE TENDON NUNBER FIGURE AMBER FORCE LAST TEST (ki s)
LAST PREDICTED
'EST FORCE (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 45 36 4-2 4-3 4-4 4-7
,630 637 632 632 626 634 627 679(627)
Based on predicted slope thru 3 year test data (based on 8
year test data).
95 142 84 126 160 76 117 110 60 63 150 159 4-13 615 4-18 612 4-24 612 4-30 588 4-31 687 4-33 612 4-35 605 4-42 663 4-37 657 4-19 647 4-14 647 4-40 658 4-10 673 3
3 611 607 655 (607) 584 683 607 602 658 653 621 630 640 650 Based on predicted slope thru 3 year test data (based on predicted slope thru 8 year test data).
51 83 100 132 4-12 665 4-11 653 4-16 627 4-25 653 6 mo.
636 624 610(575) 614 Based on actual slope thru 1
and 3 year test data (based on predicted slope thru 3 year test data).
631 Average Lift Off Force in 22 Tendons teated (estimated) nr vi srd 4-11-80 TASLE 3
4 I
a FIGURE 1-A TENDON STRESSING SE UENCE Jack /tl 13 149 1
21 17 9
5 157 153 151 185
'139 3
7 11 15 19 23 24 22 20 18 16 14 12 10 8
6 4
2 160 158 156 154 152 150 32 33 34 35 Jack ft2 53 25 45 57 65 61 49 44 26
'27 36 43 47 51 55 59 63 67 68 66 64 62 60 58 56 54 52 50 48 46 41 42 40 30 28 29 31 37 38 39 Jack 83 93 69 81 101 97 89 85 77 73 71 75 79 85 87 91 95 99 103 104 102 100 98 96 94 92 90 88 86 84 82
, 80 78 76 74 72 70 113 114 115 116 Jack
/I4 133 105 127 137 145 141 129 121 108 107ill 128 125 131 135 139 143 147 148 146 144 142 140 128 136 134 132 130 123 126 124 122 112 110 109 106 117 118 119 120
= Retensioned at 1000 hours0.0116 days <br />0.278 hours <br />0.00165 weeks <br />3.805e-4 months <br />".
Revised 4-11-80 FIGURE l-A TENDON STRESSING SEQUENCE
T 0
~v k
4 7,
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
N I