ML20010G974

Evaluation of Single Wythe Assumption to Represent Multiple Wythe Walls.

ML20010G974
Person / Time
Site:	Point Beach
Issue date:	09/30/1981
From:	COMPUTECH ENGINEERING SERVICES, INC.
To:
Shared Package
ML20010G963	List: ML20010G962 ML20010G974 ML20010G981 ML20010G988 ML20010G992 ML20010G998
References
IEB-80-11, R553.07, TAC-42896, TAC-42897, NUDOCS 8109220729
Download: ML20010G974 (4)

Text

_..

ACTION ITEM 5 EVAL; ATION OF SINGLE WYTHE ASSUMPTION TO RciPRESENT

, MULTIPLE WYTHE WALLS Prepared for Point Beach Nuclear Power Plant, Units 1 and 2 WISCONSIN ELECTRIC POWER COMPANY Milwaukee, Wisconsin s

Prepared by L

COMPUTECH ENGINEERING SERVICES, INC.

Berkeley, California i

t September,1981 l

l l

REPORT NO. R553.07 i

l . 8109220729 810915 PDR ADOCK 05000266 l G PDR

{ -.

e TABLE OF CONTENTS 1 INTRODUCTION .. . . . ... . . I 2 ANALYSIS METHODOLOGY . . . . . ... .... . 1 3 RESULTS . . . . . . . . 1 4 DISCUSSION OF RESULTS . 2 5 CONCLUSIONS .. . .... .. 2 l

l l

I

)

1 INTRODUCTION The Nuclear Regulatory Commission (NRC) staff on June 9-11, 1981 reviewed the criteria and calculations performed on IE Bulletin 80-11

• Masonry Wall Design

• for the Point Beach Nuclear Power Plant. Action item 5 resulting from the review meeting stated that with regard to out-of-plane loading, tne licensee shall demonstrate that the use of the single wythe assumption for multiple wytne walls results in a conservative evaluation with respect to frequency shift and out-of-plane drift consideration.

This short report presents the analyses that were performed, the results of the analyses, a discussion of the results, and the conclusions.

2 ANALYSIS METHODOLOGY All walls were analyzed in accordance with the procedures given in

• Criteria for the Re-evaluation of Concrete Masonry Walls for Point Beach Nuclear Power Plant.* Specifically, plate analysis was used to assess the out-of-plane response of the wall. The computer program SAP 5A was used to perform a finite element dynamic analysis. utilizing the response spectrum method.

All wythes in a multiwythe wall were assumed to respond as single wythe walls Decause of the difficulty in perifying the adequacy of the collar joint between the wythes. This was assumed to be conservative when using the re-evaluation criteria and the objective of Action item 5 is to validate the degree of conservatism.

Two double wythe walls (Wall Nos. 24 and 65-1) were selected to compare the results obtained from the wall acting either as a single or double wythe wall using tne re-evaluation criteria, in using the re-evaluation criteria the walls were assumed to have pirened supports at all appropriate boundarles. As a co'iseouence no forces are induced in the wall due to out-of-plane drift.

The validity of this assumption is addressed in Computsch Engineering Services. Inc. Report No. R553.11. Some of the results of Report No. R553.11 are incbded in th;5 report for the purpose of aodressing Action item 5. Wall 24 is 164 inches long.156 inches high and consists of two wythes of twelve inch wide units. Wall 65-1 is 109 inches long.176 inches high and consists of two wythes of six inch wide units. Each wall war anaiyzed as both a singis and double wythe wall using the same number of nodes. mesh size and Doundary conditions. Two boundary conditions were used for each wall; one simply supported on each boundary and the other fra d. For the fixed boundary condition the out-of-plane drift effects were included as reported in Report No. R553.11.

3 RESUt.TS The results of the analyses performed using the simply supported boundary conditions are given in Table 1 and 2. Table 1 compares the frequencies of each wall acting either as a single or double wytha wall. Table 2 compares the maximum stress ratios for each wall acting either as a single 1

a

or double wythe wall. The values given in Table 2 are based on the procedures given in the re-evaluation criteria. That is the walls are assumed to have simply supported boundary conditions.

The results given in Table 3 are extracted from Report No. R553.11 and provide a comparison of the single or double wythe wall with fixed boundary conditions incorporating the effects of out-of-plane drift.

4 DISCUSSION OF RESULTS From the results presented in Table 1 it is clear that the single wythe assumption is conservative with respect to frequency shift. The fundamental or first mode frequency of the double wythe wall is approximately twice that of the single wythe wall. For walls with more than two wythes the shift In frequency would be even greater. The effect of out-of-plane drift effects depends on how this is incorporated in the analysis of the walls and is further discussed in Report No. R553.11. For the case of simply supported boundary conditions, out-of-plane drif t does not Induce forces in the walls and the maximum stress ratios given in Table 2 indicate that the maximum stresses in the wall due to other out-of-plane forces for the double wythe wall are approximately one-half of those of the corresponding single wythe wall.

For the case of fixed boundary conditions, incorporating out-of plane drift effects the results given in Table 3 indicate that the maximum stress ratios for the double wythe walls are from 50 to 130 percent less than the corresponding single wythe walls .except for Wall 24 spanning in the vertical direction. In this case the maximum stress ratio for the double wythe wall is 7.5 percent greater than the single wythe wall. Therefore. for Walls 24 and 65-1 the use of the single wythe assumption to represent double wythe walls generally results in a conservative evaluation regardless of how out-of-plane drift effects are incorporated.

5 CONCLUSIONS Two walls were selected to demonstrate that the use of the single wythe assumption for multiple wythe walls results in a conservative evaluation with respect to frequency shift and out-of-plane drift considerations. The results indicate that the frequency of the double wythe walls are almost twice those of the equivalent single wythe wall. Thereforo, from frequency shift considerations the use of the single wythe assumption is conservative.

The impact on out-of-olane drift considerations depends on how this is incorporated in the analysis With the method used in the re-evaluation criterla no forces are induced in the wall due to out-of-plane drift effects and the maximum stress ratios from other out-of-plane forces in the double wythe wall are approximately one-half of those in the single wythe wall. If fixed boundary conditions are used and out-of-plane drif t effects are included, then the maximum stress ratios in the doubie wythe walls were 50 to 130 percent less than those in the single wythe wall, except for one case in wnich the maximum stress ratio for the vertical span of the single wythe wall was 7.5 percent greater than the double wythe wall.

2 i

The single wythe assumption is therefore conservative for the procedures specified in the re-evaluation criteria and is reasonably conservative for the procedure of including out-of-plane drif t effects specified in Report No. R553.11.

l 3

TABLE 1 FREQUENCY OF WALLS WITH SIMPLY SUPPORTED DOffNDARY CONDITIONS Wall No. Thickness Wythes Frequencies (!!z) 1 12 1 15.39, 37.72 24 25 2 32.06, 78.57 6 1 .15.28, 24.99, 43.97 65 - 1 12 2 30.56, 49.99, 87.95 TABLE 2 MAXIMUM STRESS RATIOS OF WALLS WITH IMPLY SUPPORTED BOUNDARY CONDITIONS Wall No. Thickness Wythes Mx/Mxa My/Mya i 12 1 .3726 .1561 f 24 s..

25 2 .1809 .0751 6 1 .4834 .1572 65-1 12 2 .2146 .0697 l-Note: Subscripts x and y denote stress ratios on horizontal and vertical strips respectively 4

TABLE 3 MAXIMUM STRESS RATIOS OF WALLS WITH FIXED BOUNDARY CONDITIONS INCLUDING OUT-OF-PLANE DRIFT EFFECTS Wall No. Thickness Wythes Mx/Mxa My/Mya 12 1 0.244 0.210 24 25 2 0.129 0.226 6 1 0.264 0.136 65-1 12 2 0.117 0.097 Note: Subscripts x and y denote stress ratios on horizontal and vertical strips respectively

-5