ML20086U095

Addendum 1 to Containment Bldg Post-Tensioning Sys Three-Yr Surveillance

ML20086U095
Person / Time
Site:	Point Beach
Issue date:	02/25/1974
From:	Johnson T, Pfeifer B, Rotz J BECHTEL POWER CORP.
To:
Shared Package
ML20086U063	List: ML20086U062 ML20086U070 ML20086U079 ML20086U085 ML20086U094 ML20086U095 ML20086U101 ML20086U104 ML20086U111 ML20086U117
References
NUDOCS 9201070206
Download: ML20086U095 (31)

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4 ADDENDUM NO. 1 l

1 WISCONSIN ELECTRIC POWER COMPANY

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l WISCONSIN MICllIGAN POWER COMPANY t

POINT BEACil NUCLEAR POWER PLANT UNIT NO. 1 l#

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t i.

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f CONTAINMENT BUILDING i

POST-TENSIONING SYSTEM TiiREE-YEAR SU RVEILLANCE yl i

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4

1. r

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B. h '. PL'ei t e r

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Reviewed By

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Dechtel Power Corporation

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J. V Rotz P'

San Francisco, California Wd Approved By__

February 25 1974

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E.

Johnson

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i NI TABLE OF CONTENTS I

section Page

1.0 INTRODUCTION

1-1 2.0

SUMMARY

AND CONCLUSIONS 1-1 2.1 Summary 1-1 2.2 Conclusions 2-1 3.0 GENERAL 3-1 4.0 TENDON FILLER AND END AMCHORAGE ASSEMBLY 4-1 4.1 Sheathing Filler 4-1 4.2 End Anchorage Assembly 4-1 5.0 DETENSIONING AND WIRE REMOVAL 5-1 5.1 Lift-Off Forces 5-1 5.2 Wire Inspection 5-3 5.3 DiscLntinuous Wires 5-3 6.0 WIRE TESTING 6-1 6.1 Specinen Selection and Preparation 6-1

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6.2 Test Equipment 6-1 f

6.3 Test Equipment Calibration 6-2 6.4 Wire Test Procedure - Long Samples 6-2 t

6.5 Test Resulta 63 I l

6. 5..

Percent Elongation at Ultimate Strength 6-3 LI 6.5.2 Yield Strength 6-3 hi 6.5.3 Ultimate Strength 6-4 6.5.4 Comparison with Original Acceptance Test Data 6-5 6.5.5 Fracture Characteristics 6-5 6.5.6 Specin' ins with Surface Defects 6-6 r

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7.0 RETENSION1NG AND FILLER INSTALLATION 7-1 e

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i Figure Title

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3-1 Location and Identification of Surveillance Tendons 5-1 Average Normalized Wire Force vs..

Time - Hoop Tendons 5-2 Normalized Wire Force vs. Time -

l Vertical Tendons 5-3 Average Normalized Wire Force vs.

Time - Dome Tendons

{

,' i 6-1 Wire Test Machine Assembly

}e D-1 thru D-11 Wire Inspection Data Sheets A*

e.

E-1 thru E-9 Tendon End Anchorage. Sketches

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'G-1 Photographs of the Cup-and-Cone Fractures G-2 Photographs of Surface Appearance I

of Wire from Tendon V-58 G-3 Cross-Section Through Area of Pitting of Sample V-120-B and Photomicrograph i

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i LIST OF TABLES I

l Table Title 4-1 Sheathing Filler and Anchorage Assembly I

Surveillance Data

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5-1 Dontensioning and Wire Removal Data 5-2 Normalized Lif t-Of f Forces Tar Three-Year Surveillance 6-1 Test Results - 100 Inch Gage Length Wire Specimens 6-2 Tensile Test Results - 10 Inch Gage Length Specimens 6-3 Acceptance Test Data on Wire Used in

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Fabricating Tendons 7-1 Retensioning and Sheathing Filler C

Installation Data C-1 Laboratory Analysis of Sheathing Filler F-1 Laboratory Tests of Tendon Wire from 9

vertical Tendon V-58

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1, February 25, 1971 1,0

_I_ti_T RODU CT i nu jong The Tendon Surveillance Program is a systematic means of 4

assessing the continued qunlity of the post-tensioninq system.

The curveillance consists of periodic inspection i

of a minimum of nine pre-selected surveillance tendons

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(three hoop, three vertical and three dome) for physical con d i ti on.

This provides a measure of confidence in the

.l condition nnd functional capability of the system snd an opportunity ior timely corrective measures should adverse

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conditiors (such as severe tendon wj re corrosion, where the reduction 1;. the cross-sectional area due to corrosion fs so substantial, that the ultimate tendon wire strength falls below the required minimum ultimate sts

.th) be detected.

s Tnis report covers the three-year tendon surveillance for Point Beach Nuclear Power Plant Unit No.1 as specified by Plant FSAR, Section 15, Paragraph VII, Tendon Stress I

Surveillance.

This report 14 intended to meet the require-ment of contract designated under Purchase Order No. 10696.

h 2.0

SUMMARY

AND CONCLUSlONS 2.1

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-Summary

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Lift-7ff forces in all tendons exceeded the minimum 1

effective desigr. prcstress force, which considers 1

-f losses due to concrete creep and shrinkage and stool

g. i relaxation.

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End anchorage assemblies were founs to be in accept-q [

able condition with no sign of development of adverse o

conditiens such-as progressive corrosion.

Some millacale and a minor amount of corrosion were present L

on shims and bearing plates this is presumed to have

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1 been present at the-time of installation.

The bottom anchorage of vertical tendon V-56 was S

I surveyed to determine the effects of concrete cracks and dripping water near the bearing plated No frec water was observed inside the grease cap, and there f'

i h was no indication of emulsified water within the sheathing filler.

The bottom anchorage and corrosion

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protection system of vertical tendon V-56 shows no L

ovidence of progressive adverse deterioration.

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The tendon wires were found to contain minor scratches, j

.j die marks, heat treating discoloration and some minor localized corrosion sparsely distributed along the j

length of the wire.

This was also observed during l

the one-year surveillance and is presumed to have been present at the time of installation.

All ten-don wires inspected were continuous.

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t Mechanical tests of specimens, with and without sur-face imperfections, indicated the physical proper-i ties (yleid strength, ultimate strength and percent elongation) of the wire exceed initial acceptance requirements.

i No abnormal discoloration was observed in sheathing filler samples.

Laboratory analysis of samples f rom i

each tendon sheath showed the amount of deleterious constituents to be well within established acceptance j

levels.

i 2.2 Conclusions j

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Based on the tests and investigation described here-3

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_in, and on comparison of data contained in this i

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. report with data contained in the one-year tendon y

' surveillance report, it is concluded that the post-I tensioning system in-the Containment Building for 1

I f Point ~Deach Nuclear Power Plant, Unit No. 1 shows i

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no evidence of progressive adverse deterioration.

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3.0 GENERAL The three-year surveillance of Point Beach Unit No. 1 Containment Building Post-Tensioning System began in July,1973 approximately three years after completion of the containment structural integrity test which occurred in June, 1970.

This surveillance consisted of the followings (1)

Visual and laboratory examination of sheathing filler.

f (2)

Inspection of anchor assembly for deleterious con-i dition:

such as corrosion, cracks, missing wires i,

or off-size buttouheads.

(3)

Measuring shim dimensions and anchor head buching projection to determine lift-off elongation (clear distance between bearing plate and anchor head).

(4)

Measuring lif t-off loads.

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(5)

Measuring elongation at 0.8f ultimate strength of tendon wEro()80% of minimum i

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-(6) 4 Detensioning tendons and checking wire continuity 1

by pulling each wire and observing its movement at the opposite end.

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Removal of a minimum of one wire from each tendon

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for examination and testing.

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Retensioning tendons.to lift-off force measured in k))

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i item (4) above, lese the effect of any wires removed i n/

hU and measuring corresponding tendon clongation.

(9)

Visual inspection of wires removed from tendons.

n (10)

Testing of wires removed from tendons for yield p.,

and ultimate strength and percent elongation.

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(11) t Evaluation of test and inspection results to assess the gener-condition of the post-tensioning system and to evaluate time dependent factors, such as pre-stress losses and corrosion.

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This work was conducted in accordance with "Surveillanco j

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Procedure for Containment Building Post-Tensioning System",

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, Revision 3, and modifications thereto, now incorporated j

into Revision 4, included in Appendix A.

j-l The identification and location of surveillance tendons i

are shown in Figure 3-1.

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VERTICAL TENDONS DOME TENDONS PLAN PLAN 9

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FIGURE 3-1 Location and Identification of Surveillance Tendons

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4.0 TENDON FILLER AND ANCHORAGE ASSEMBLY q

1 5 The results of field inspection of the tendon sheathing filler and the end anchorage assembly are shown in Table 4-1 and Appendix E.

k The bottom of vertical tendon V-56 was also inspected to determine if water seeping from a nearby concrete crack l

was entering the anchorage assembly.

The results of this inspection are contained in Appendix H.

I 4.1 Sheathing Filler i

i I

Samples of filler were removed from each of the tendon sheaths and visually examined.

All samples were dark brown, indicating no discoloration caused by impurities.

Laboratory examination (see Appendixc ) revealed that deleterious product content of all samples tested

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was within established acceptance limitn.

,i Trapped air was found inside three of the six inspected

,1 dome sheathing filler caps.

Portions of the anchor J:

if head and shims in proximity to these air pockets showed

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no significant change in corrosion level, j

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t t g 4.2 End Anchorage Assembg The end anchaorage assemblies were found to be in acceptable condition.

Millscale and minor corrosion were noted on the original millstock surfaces of shims and bearing plates; surfaces cut for final f abrication showed slight spotty discoloration.

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These conditions are similar to those generally found f

prior to sheathing filler installation and thus, do not indica te subsequent corrosion.

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I 5.0 DETENSIONING AND WIRE REMOVAL 1

The data and observations obtained during detensioning and i

g wire removal are shown in Table 5-1.

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5.1 Lift-off Forces Tendon lift-off forces obtained during the one-year and l

three-year surveillances are listed in Table 5-1 (columns i

3 and 5).

To provide a common basis for comparison, tendon lift-off force is converted to lift-off force per wire and normalized to account for the following effects:

a)

Structural deformations (a function of the post-tensioning seqoence).

s-2' b)

Initial lift-off force deviation from seven-tenths of minimum ultimate tendon wire strength.

it c)

Changes in lift-off force resulting from detensioning i;

and retensioning of the tendon during the surveillance, t ',

d)

Removal of wires during the surveillance.

l Normalized lift-off force is obtained by multiplying il measured lift-off force by the normalizing factor (see j

formulae in Appendix D).

These factors are listed in ll 0[%g

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Table 5-2 along with the normalized lift-off force per irie wire for each tendon.

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ror double-end-stressed hoop and dome tendons, an average of the lift-off force at each end is used.

The normalized lift-off forces are plotted on the Force vs. Time charts

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(Figures 5-1 through 5-3) which provide a direct comparison l 18 of measured versus predicted loss trends.

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The predicted loss trend is based on a stress loss of 27.3 ksi over a period of 40 years (for hoop, dome and vertical L

tendons - from plant FSAR, Section 5), au;uming losses lE {

diminish exponentially with time and 70% of the losses lf occur in the first year.

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With an average stress level at installation of 0.7 fpu l[

l (8.23 k/ wire), the predicted average forces after one j

year and at the end of 40 years are 7.29, and 6.89 kips jj ~

per wire respectively.

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The trend of prestress losses, based on average values I

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for each tendon group for the one-year and three-year l

surveillances,-indicate that the actual prestress losses correlate closely with the predicted prestress leases.

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The apparent force increase for hoop tendon BD-38 and dome

[jh tendon D2-23 between the one-year and three-year survell-lances (rigure 3-3) is the result of possible measurement error and procedural change for lift-off determination.

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The tendon lift-off force during the one-year tendon surveillance was identified when the cound produced by

!i tapping on the shims with a small hammer changed to

'l indicate rolcase from compression.

The procedure was slightly modified for the three-year tendon surveillance to assure that none of the shims were carrying load at the time that the lift-off force was measured.

Lift-off is now identified when all shina can be moved by tapping with a hammer as the load on the jack is in-i creased.

Considering a 1.0% prestress loss between the one-year and l

three-year surveillances and an estimated measurement error of 22.0% per surveillance, the three-year wire force level

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should be within +3.0% and -S.0% of the one-year surveillance

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normalized lift-off wire force. Values obtained during the j$

three-year surveillance f all within this range.

Jk 5.2 wire Inspection UN1?

The results of inspection of each tendon wire removed

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for surveillance are shown in Appendix D.

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some minor surfcce imperfections (abrasions, die marks, m

and discoloration) were found on all wires removed.

L 4 Wires removed from hoop tendon BP-23 and vertical tendon

[h D V-120 contained some isolated pitts less than 3 mils

{5) in depth (see Figures D-1 and D-7).

I The results of a microscopic examination of pitted wire L

are shown in Appendix G.

Examination of the pitted wire showed no evidance of stress corrosion, hydrogen embrittic-f.

ment or cracking.

Since too reduction in wire cross-sectional area was not significant and no cracking or em-

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brittlement wau observed, no significant decrease in tencile strength due to loss of metal would be expected.

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I These observations are confirmed by tensile strength test

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results shown in Tables 6-1 and 6-2.

The lack of stress corrosion and hydrogen embrittlement cuggests that oxi-3 dation occurred before tendon vensioning.

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i Review of tendon installation records indicates that 1

the original wire condition for DF-23 and V-120 was classified ar "C" (light, remorable red oxide) and that t

these tendons remained in the tendon sheaths for from

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two to four weeks prior to the installation of the shcath-ing filler.

This indicates that the corrosion observed most I

likely occurred before tensionin and installation of P

the sneathing filler.

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1 5.3 D_iscontinuous Wires F

No discontinuous wires were found during this post-tension-ing system surveillance.

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i TABLE 5-2 Normalized Lift-Off Forces

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For Three-Year Surveillance I

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'1hree-Year Ibrunlized Lift-Of f Force Per Wire Kuk thrnalizing Each End hndon Amracy Factor KIPS KIPS 10-38 B

1.000 6.98 7.20 D

0.993 7.41 BF-23 B

1.021 7.33 7.20

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F 0.967 7.07

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0.973 7.37 7,11 El D

0.955 6.85 V-3 T

0.950 7.30 r

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1.006 7.50 l

V-120 T

0.986 7.36 bl-25 A

0.962 7.30 7.19 D

0.957 7.08 D2-23 B

0.974 7.59 7.40 i

E 0.945 7.20 1

D3-25 F

9.980 7.16 7.24 I

C 0.970 7.32 Note : T

'Ibp of vertical tend:m A to P - nearest buttmsa to end of terJcn O

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MLnitssn Effective Design PresPress l

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10 20 30 40 Tine After Initial *Densicrurg f(ears)

I FIGRE 5-1 Vertical Tervicri ?brr.nlized Lift-off Wire Fbrte vs. Tine e

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FIGURE 5-2 Ikxp Tendm Averaye Nor:mlized Lif t-off tum Ibrae vs. Time

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O 6.0 WIRE TESTItJG l

6.1 Specimen Selection and preparation Appendix D identifies the.specimrins selected for testing.

A typical section of wire (approximately 9 '-0" long) was cut from each end and from the middle portion of each wire.

The specimens were trimmed to a length of 101 inches, fitted with stressing washers and buttonheaded to provide a gage length l

of approximately 100 inches (clear distance between buttonheads).

More than three wire samples were removed from four -endon wires for additional measurements to assure complete representation of all wire conditions.

As specimens were removed i

from the wire, they were tagged with the following l

informations i

(1)

Tendon identification number.

i (2)

Sample number indicating location of specimen, j

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These tags remained

h the specimens through completion of testing.

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6.2 Test Equipment i

The test assembly used for testing nominal 100 inch j

gage length wires is shown in Figure 6-1.

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A tensile force was applied to the wire through

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the stressing washers inserted in the pulling adaptors.

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one adaptor was screwed onto a threaded 1-1/8" diameter f

rod anchored to the end of the reaction frame. The L

other pulling adaptor was screwed onto the threaded 0

portion of the-ram plunger.

The 10"-stroke two-way ram was bolted to the pulling end of the reaction f rame.

Tension was applied to the wire by pressurizing the

" pull" side of the two-way ram with a hydraulic pump.

g The force applied to the wire was obtained from

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calibrated pressure gage readings.

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Displacement to one percent elongation was measured utilizing two dial extensometers (having a two-inch l

l travel and lowest division of 0.001 inches) mounted 3

as shown in Figure 6-1.

The dial mounting bar was anchored rigidly to the reaction frame at its midpoint.

fd The extensometers were positioned on the mounting bar to measura the change in distance between the two index rods attached to the pulling adaptors.

This, after preloading to seat bt.ttonheads into pulling l

washers, enabled measurement of wire clongation.

The elongation under load at failure (ultimate strength) was obtained utilizing a rule attached to the gage mounting bar at the ram-end to measure the relativa displacement between the index rod and the dial mounting bar.

Measurements were read to the nearest 1/64 inch.

J 6.3 Test Equipment Calibration The pulling assembly (gage and ram) was calibrated in a testing machine accurate to +0.164 and -0.08%

of load reading prior to the testing of specimens.

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6.4 Wire Test Procedure - Long Samples N

4 The test procedure used parallels that of ASTM Speci-U cation A 421-65 with the exception of gage length.

A nominal 100 inch gage length (instead of 10") was

j chtsen to obtain a longer sample more representative l

t, of the actual in-place strength of the wire.

The 100

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inch gage length specimens may indicate a lower ultimate strength and less ductility (olongation) than 10 inch y

,p' specimens, since failure will occur at the weakest i

point in the wire (equivalent to the lowest value that would be obtained from ten 10 inch specimens).

Elonga-

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tion under load at failure will also tend to be less due to distribution of elongation at the neck-down area 4

,3, over a length of wire ten times that of the nominal 10 inch gage length specimen.

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O 6.5 T st Results

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The results of tests on 100-inch gage length samples are shown in Table 6-1.

The results of tests on i

10-inch gage length samples are shown in Table 6-2.

Six 10-inch gage length wire samples from the first wire removed from vertical tendon.V-58 were tested by Armco Steel Corporation of Kansas City, in accordance with ASTM 421-65 to obtain independent test data on the yield strength and ultimato strength.

The resulte listed in Table 6-2 and Appendix F.

are 6.5.1 Percent Elongation at Ultimate Strength, Due to the effects discussed in paragraph 6.4, wire 1

tested using 100-inch gage length specimens ' A expected to exhibit less elongation at failure than identical wire tested using 10-inch gage length i

specimens.

Based on other test data (1), a wire exhibiting a 4% ultimate elmgation by 10-inch gage length tests is expected to exhibit a 3% ultirrate i

elongaticn by 100-inch gage length tests.

All wires from the nine tendons exhibt t<M mlongation l

l un' der load at f ailure greater than 31.

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6.5.2 Yield Strength i

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t' The minimum and maximen measured yield stress of 198 g

kai and 225 kai for the one year tendon surveillance f

compare well with 191 kai and 217 kai measured for j

the three year surveillance.

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The test results compar hg elongation at failure of l

{ll 10-inch and 100-inch specimens are reported in Consumers Power Company, Containment Building Post-Tensioning

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System One-Year Surveillance, Palisades Plant Unit 1, Docket No. 50-255.

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The yield strength of all wiro specimens tested,

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except one from tendon V-58, exceeded the mini-t i

mum yield strength of 192 kai at 14 elongation.

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The test result for sample No. I from V-58 was i

190.5 ksi or within less than it of the minimum i

yield strength.

This tust result is not consider-ed indicative of tendon wire deterioration or actual yield strength becaur.e test results for three addi-I t

tional 100-inch samplea and six 10-inch samples l

f rom the same wire were acceptable.

i 6.5.3 Ultimate Stre,ngtn The ultimt e strength of all but two of the wire specimens tested ex.ceeded the specified minimum ultimate strength of 2401st.

The test results of wire sample No.1 and wire sample No. 4 from l

vertical tendon V-58 indicate an ultimate strength of 229 ksi and 238 kai respectively.

The acceptance test data litsted in Table 6-3 for wire used in ver-tical tendon V-58 indicates an ultimate stress f rom 250 ksi to 259 kai.

Ultimate strength for wire aamples from vertical tendon V-58 determined during the one year surveillance varied between 240 kai to

({)

249 kai.

The low indicated ultimate strength obtained for i

wire sample No. 1 and_ wire sample No. 4 from vertical tendon V-58 could be the result of any one or combina-tion of the following (a) Gage not properly adjusted to zero at beginning j

of test; (b) Misreading the gage at time of failurer (c) Temporary malfunction of test equipmant (such as

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foreign material in the hydraulic system causing

_ spurious gage readings).

In addition, the two test results for tendon V-58 wire No.

1, are not indicative ofitendon wire deteri-oration or low strength for the following reasonar l

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i' (a) Tests on four additional 100-inch specimens f rom the same wire indicated wire strea.gth exceeds specified minimum values.

(b) Tests on six additional 10-inch specimens conducted by an outside laboratory also l

indicatt;d wire strength in excess of speci-i fied minimum value.

t (c) Tests on three 100-inch specimens from a second l

i wire removed from tendon V-58 were acceptable.

(d) Both specimens exhibited ductile type failures indicating that the failures were not initiated by stress corrosion or hydrogen embrittlement.

(e ) Corrosion observed on these specimens was less than that observed on other wire specimens whose strengths exceed specified minimum ultimate i

s treng th.

6.5.4 Comparison With Original Acceptance Test Data i;

The range of ultimate strength of the samples tested y

compcres well with that obtainedlin acceptance tests

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1 (see Table 6-1).

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6.5.5 Fracture Characteristics

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All breaks indicated a necked down cup-and-cone tracture area.

Approximately 50% of all fractures i

r occurred at the buttonheads and the majority revealed tear characteristics due to eccentric loading of the buttonhead.

The ultimate stress of all tested wire samples with breaks at the buttonheads exceeded the p

minimum specified ultimate strength of 240 kai.

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Figure G-1 of Appendix G shows typical tendon wire breaks.

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6.5.6 Specimens With Surface Defects j

1.

A comparison of wire test result-for 100 inch specimens with and without surface defects in-

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dicates that there is no detectable decrease in

' l strength and physical properties of wire speci-mens with surface defects.

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TABLE 6-1 Test Results fer 100" Gage Length Wire Specimonn T E NW)N SAMPl.E 11 YIELD ULTIMATE PERCENT LOCATION (2) i NO.

NO. (1)

STRESS (KST)

STRESS (K51)

ELONCATION OF FAILURE

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6D-38 1

202 252 4.8 M

2 202 242 5.3 M

3 216 253 5.7 bH f

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205 256 5.6 eH 2

201 250 5.7 M

3 207 245 5.0 su I'F - %

1 210 253 5.2 M

2 204 250 5.7 M

3 207 241 5,0 g

v-l 1

215 258 4.4 su 2

220 264 4.5 BH 3

212 254 4.1 BH V-58 #1 1

191 229 4.9 M

2 205 52 5.0 H

3 197 241 4.9 H

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4 199 238 5.3 H

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198 244 5.1 H

6 201 245 4.4 BH i

V-58 f2 1

201 244 5.9 H

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209 250 4.4 BH 3

205 248 4.9 M

V-120 #1 1

206 254 5.1 M

2 204 254 4.2 M

3 208 262 4.4 CH V-120 #2 1

205' 249 4.!,

gig 2

196 248 4.9 M

3 198 241 4.8 H

D1-25 1

218 259 4.6 H

2 213 258 4.6 BH 3

213 253 4.7 nH DJ-23 1

212 253 4.1 BH f

2 216 256 4.4 BH 3

217 255 4.2 BH 4

206 5

3.8

'N D I-2 5 1

212 4.0 4H 2

216 4.2 BH 3

216 461 4.9 BH

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Mt es : (1).ec Ap; andia D for neple location on wite (2) Fatlure is toc ted within !" of Buttophend (HH) or within Midd'e (M) portlin of wi re.

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TABLE 6-2 Tensile Test Fesults for 10-Inch Gage Length 6.1re Specimenb from j

Tendon V-5b Yield Strength tendon Tendon Wire at tilt tias te Percent No.

sample 11 Elongation Stress (ksi)

Elongation (ksi) v-58 #1 A

202.1 242.1 S.1 f

B 204.1 242.9 4.7 C

203.7 243.3 4.6 D

207.3 246.1

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E 204.5 243.3 4.0 i

r 202.5 242.1 4.6 i

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1.

Test by Armco Steel Corporation, Kansas City, Missouri

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For tendon wire sample location, see Appedix D and Figure D+$.

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i TADLI: 6-3 Acceptance Test Data on Wire

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'Jsed In Fabricating Tendons 1

Ultimate Strength (ksi)

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Tendori Coil No._

lleat No.

Sample A Gample B 3

Dr23 117 13265 242 242 598 25486 247 248 597 25486 248 251 lid 3 9 754 32499 247 246 1

748 32499 255 t4 l

771 32499 257

.i 0r54 327 13461 253 252 326 13461 253 25l 318 13461 253 257 D125 369 25998 247 262 s

368 25998 253 261 376 2503d 251 263

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D223 257 26147 254 255

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258 2t147 257 264 j

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D325 735 26184 255 254 j

726 26184 257 257 727 26104 249 249 V3 51

'3042 254 252 49 33042 256 253 j

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V58 92 14130 250 253 89 14130 255 253 l

9 14130 240 259 4

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V120 932 33047 258 259

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933 33047 252 254 L,

Note:

The specified minimum ultimate strength in 240 hai

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7.0 RETENSIONING AND FILLElt INSTALLATIO!1 1

The data obtained during retensioning and filler installation h

are shown in Tabic 7-1.

The tendons were retensibned to approximately the same stress level indleated by lift-off force data obtained during this surveillanco.

Additional clongation was measured as indi-cated by data.

1 "he volume or sheathing tiller removed was recorded.

The rentensio.'ng information provides input data for use in the next a a duled surveillance.

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