ML15244A268
| ML15244A268 | |
| Person / Time | |
|---|---|
| Site: | Oconee  |
| Issue date: | 06/25/1987 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML15244A267 | List: |
| References | |
| IEB-80-11, NUDOCS 8707010621 | |
| Download: ML15244A268 (5) | |
Text
NON-PROPRIETARY SAFETY EVALUATION REPORT BY THE OFFICE OF NUCLEAR REACTOR REGULATION ARCHING ACTION THEORY FOR MASONRY WALLS OCONEE NUCLEAR STATION, UNITS 1, 2 AND 3 DUKE POWER COMPANY DOCKET NOS.: 50-269, 50-270, AND 50-287 The previous Safety Evaluation Report (SER) on masonry walls for Oconee, Units 1, 2, and 3, (Reference 1) has concluded that all the walls will withstand the specified design load conditions with the exception of 82 unreinforced concrete masonry walls, which require the staff review of the results of a confirmatory test program intended to verify the applicability of the "arching action" theory used by the licensee for the evaluation of those 82 walls. The staff has re viewed three test reports (References 2, 3, and 4) submitted by the licensee and found that the test results have verified the applicability of the arching action theory used by the licensee for the 82 walls. Therefore, the staff has concluded that Oconee, Units 1, 2, and 3, have fully satisfied the requirements for IE Bulletin 80-11. The staff's evaluation results follow.
The arching action theory used by the licensee was originally proposed by E. L. McDowell, K. E. McKee, and E. Sevin in 1956 (Reference 5).
The proposed theory can explain and predict a much greater strength of unreinforced masonry walls than would be predicted on the basis of conventional bending theory for those walls butted up against rigid supports at the top and bottom and subject to out-of-plane bending. The proposed theory was based on a specific mode of response of unreinforced masonry walls subject to out-of-plane bending. The mode of response of walls is described as follows:
When a load is applied perpendicular to the wall and reaches certain magnitude, cracks will develop on the tension sides of the most stressed regions of the wall, which are at the middle and two ends.
If the magnitude of the applied load is increased, the top and bottom portions of the wall will rotate as rigid bodies about their ends. Since the supports are rigid, three compressive forces are created on the compression sides of the ends and middle of the wall from the rotational movement of the rigid bodies. Since the compressive forces at the ends are on the opposite side of the wall with respect to the compressive force at the middle, they form resisting couples (bending moment) to resist further rigid body rotations until the masonry blocks crushed. This type of mode of response resembles that of a three-hinged arch structure and, therefore, the theory is called arching action theory.
An extensive dynamic test program of brick walls conducted by B. L. Gabrielsen and K. Kaplan (Reference 6) has confirmed the validity of the arching action theory in the application of brick walls subjected to blast waves. This confirmation was demonstrated by the authors in the Figure included as. There is excellent match of centerline displacement time histories between the measured and predicted values.
8707010621 870625 PDR.ADOCI( 050o0269j
-2 The test program conducted by the licensee was to demonstrate the validity of the arching action theory used for qualifying the 82 unreinforced concrete masonry walls subjected to earthquakes at Oconee Nuclear Station, Units 1, 2, and 3. The test program consisted of a pilot wall and four additional test walls. Two of the walls had openings and two of the walls had attachments.
The test walls were constructed in as similar a manner as possible to the walls at the plant.
Two actuators, one at the top and the other at the bottom, have oriented per pendicular to each test wall.
Each actuator is controlled through a displace ment command signal.
The displacement time histories of selected earthquake motions were used as input commands to drive the actuators. Two different sets of recorded time histories have been used as bases to develop displacement time histories. These recorded time histories were 1940 El Centro and 1952 Taft (Lincoln School Tunnel).
These time histories were so adjusted that their re sponse spectra would envelop the design response spectra at the top or bottom of the walls at Oconee. The duration of input motions was chosen as 30 seconds, which was the same as the design time history of Oconee Units 1, 2, and 3. An intensity level of input motions approximately three times the envelope floor spectra from a safe shutdown earthquake (SSE) for the Oconee, Units 1, 2, and 3, was applied to all test walls. During the dynamic tests, the out-of-plane de flections, accelerations, total thrust force, wall curvature, faceshell strains, and in some cases joint openings, were measured.
In general, all the walls were tested in two stages - uncracked and cracked.
Between the two stages the walls were intentionally cracked by applying a load at midheight of the walls such that cracks at the top, center, and bottom bed joints were clearly visible. Each test wall was subjected to several high intensity levels of input motions of both El Centro and Taft types of time histories scaled up from 100 percent to 300 percent of the envelope floor spectra for walls at Oconee, one at a time, for both uncracked and cracked walls.
The staff has evaluated and approved the proposed test program and witnessed the test and reviewed the test reports. Considering the fact that the arching action theory, which was used to qualify the 82 unreinforced concrete masonry walls at Oconee, has been validated by the test results, the staff has con cluded that Oconee, Units 1, 2, and 3, have fully satisfied the requirements for IE Bulletin 80-11.
Principal Contributor: J. Ma Dated:
-3 REFERENCES
- 1. Safety Evaluation Report on Masonry Wall Design, IE Bulletin 80-11, Oconee Nuclear Station, Units 1, 2,.and 3, March 14, 1985.
- 2. Oconee Nuclear Station, Masonry Wall Confirmatory Test Program, Results from Testing Walls No. 0, 1, and 2, Report No. R561-70-05, December 1985.
- 3. Oconee Nuclear Station, Masonry Wall Confirmatory Test Program, Results from Testing Walls No. 3 and 4, Report No. R561-70-06, December 1985.
- 4. Oconee Nuclear Station, Masonry Wall Confirmatory Test Program, Correlation with Arching Theory and Summary of Results, Report No. R561-70-07, December 1985.
- 5. "Arching Action Theory of Masonry Walls," E. L. McDowell, K. E. McKee, and E. Sevin, American Society of Civil Engineers.
Journal of the Structural Division. Proceedings of the ASCE.
ST2, Paper 9.5, March 1956.
- 6. "Arching in Masonry Walls Subjected to Out-of-Plane Forces,"
B. L. Gabrielsen and K. Kaplan. Earthquake Resistant Masonry Construction -
National Workshop. NBS Building Science Series 106.
ATTACHMENT 1 1.0 0.10 C
C 0.1 Measured Predicted 0.001 1
2 5
10 20 50 100 200 Time (msec)
Fig. 14 Predicted and measured wall centerline displacements for a rigidly arching wall vs time from initial blast loading, wall no.
87, second test.
Loading pressure -
15 psi (103.5 kN/m 2) 302
PmJPRIETARY INFORMAON NOTICE THE ATTACHED DOCUMENT CONTAINS "PROPRI ETARY INFORMATION" AND SHOULD BE HANDLED AS NRC "OFFICIAL USE ONLY" INFORMATION.
IT SHOULD NOT BE DISCUSSED OR MADE AVAILABLE TO ANY PERSON NOT REQUIRING SUCH INFORMA TION IN THE CONDUCT OF OFFICIAL BUSINESS AND SHOULD BE STORED, TRANSFERRED, AND DISPOSED OF BY EACH RECIPIENT IN A MANNER WHICH WILL ASSURE THAT ITS CONTENTS ARE NOT MADE AVAILABLE TO UNAUTHORIZED PERSONS.
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REC'D W/LTR DtD NRC Form 190 (4-78)
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