ML19261E910

Rept of Evaluation of Integrity of Vertical Tendon Upper Bearing Plate. Prepared for General Public Utils Svc Corp

ML19261E910
Person / Time
Site:	Three Mile Island
Issue date:	08/29/1973
From:	Artuso J PROFESSIONAL SERVICE INDUSTRIES, INC. (FORMERLY PTL-I
To:
Shared Package
ML19261E908	List: ML19261E910
References
NUDOCS 7910170968
Download: ML19261E910 (4)

Text

. ,- August 29, 1973 ENCLOSURE 3 Report of Evaluation of Integrity of Vertical Tendon Upper Bearing Plate FOR GPU Service Corporation PROJECT: Three Mile Island Unit #1 Containment Building SCOPE: Evaluate the integrity of the vertical tendon upper bearing plates to determine if the bearing plates beared properly without signifi-cant differential displacement into the concrete. The plates which should be specifically evaluated were V26, 31, 70, 76, 79,105 & 126.

The evaluation shall include the following:

a. Whether concrete adjacent to the bearing plates consisted of original concrete - (no patching) .

b. Whether there was evidence of any differential displacement between the bearing plate and adjacent concrete.

c. Can the bush hammered surface adjacent to the bearing plate mask any differential displacement. (The b'tsh hammering was performed to improve the drainage of water around the bearing plate).

d. Document visual evaluation of the concrete condition at the bearing plate for evidence of differential displacement as indicated by cracks, spalling, etc.

I483 194 qqjol10 Y

- Discussion &

Conclusions:

A thorough examination was made of the subject bearit.g plates and adjacent ones to develop evaluation regard-irg above items. This was concluded by the writer on 8/27/73 using visual ext .ation both the naked eye and 5 power magnification.

The following evaluation was gleaned from the examination in regards to the above items.

a. There was no evidence of any patching adjacent to the bearing plates. This was evidenced by the integrity of the concrete and specifically by the consistent texture, surface trowel marks, hydration coloration and uniform distribution of the coarse aggregate at the concrete surface.

b. There was no evidence of differential displacement of the bearing plate with relation to the adjacent concrete. This was evidenced by the sound bond developed between the concrete to the edges of the bearing plates. An adjunct to the evalua-tion was the presence of lapped concrete over the edges of the bearing plates at various locations. Since concrete cracks at about 0.3 percent tensile strain any displacement of less than 0.001" would create a visible crack in the lapped concrete.

There were none, and therefore there could not be any differen-tial displacement.

1483 195

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c. The bush ha=mered surface could not mask any dif ferential movement. In f ac t the bush hammered condition would more easily expose any signs of displacement. It enables evalua-tion of the adjacent concrete to determine existence of any patching as noted in item (a) above.

d. The examination revealed a complete absence of cracks and spalling which would be indicative of differential dis-placement. An area of minor spalls at one edge of bearing plate (V79) was attributed to localized linear shrinkage.

There was no perceptible depth of shrinkage at this point.

(See photo of V79). The sound bond of the other three edges precluded any differentia-1 movement of the bearing plate.

e. Any significant differential displacement of the bearing plate and adjacent concrete would be characteri-ed by a shear failure exhibited by cracks near the edge of the bearing plate. The pre-stressing load would compress the bearing plate and take up any settlement of the concrete beneath the plate that would have occurred during migration of air and water during setting of the concrete. Apparently, the placement technique minimized this phenomena to the extent that no significant differential displacement occurred. It is estimated that the maximum settle-ment of the concrete would be in the magnitude of several thousandths of an inch. This estimation is based on an 14!33 196

-4 an evaluation of the condition of concrete placement and concrete mix characteristien , The sound bond of the concrete to the edge of the plate indicated the proper transfer of stress to the concrete and reinforce-ment beneath the bearing plate without significant differential displacement.

s v'

/ Joseph T. Artuso JTA /j a Pittsburgh Testing Laboratory 1483 197