ML20011A476

Evaluation of Single Wythe Assumption to Represent Multiple Wythe Walls.

ML20011A476
Person / Time
Site:	Point Beach
Issue date:	09/30/1981
From:	COMPUTECH ENGINEERING SERVICES, INC.
To:
Shared Package
ML19312F019	List: ML19312F018 ML20011A461 ML20011A463 ML20011A466 ML20011A469 ML20011A476 ML20011A483 ML20011A484 ML20011A488
References
IEB-80-11, R553.07, R553.07-R01, R553.07-R1, TAC-42896, TAC-42897, NUDOCS 8110130463
Download: ML20011A476 (6)

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EVALUATION OF SINGLE WYTHE ASSUMPTION TO REPRESENT MULTIPLE WYTHE WALLS Prepared for Point Beach Nuclear Power Plant, Units 1 and 2 WISCONSIN ELECTRIC POWER COMPANY Milwaukee, Wisconsin Prepared by I COMPUTECH ENGINEERING SERVICES, INC.

Berkeley, California September,1981 REPORT NO. R553.07 t

Revision 1 8110130463 811007 PDR ADOCK 05000266 O PDR

TABLE OF CONTENTS 1 INTRODUCTION . ... .. .. ... . 1 2 ANALYSIS METHODOLOGY . . . . ... . .. . 1 3 RESULTS . .. . . I 4 OISCUSSION OF RESULTS 2 5 CONCLUSIONS . . .. . . . . 2 4

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 Walt Design' for the Point Beach Nuclear Power Plant. Action item 5 resuliing from the review meeting stated that with regard to out-of-plane loading. the licensee shall 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 dr ,t consideration.

. , short report p esents the analyses that were, performed. ine resuits of ine a.1alyses, 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 Bear.h Nuclear Power Piant." Specifically, plate analysis was used to assess the out-of plane response cf the wall. The computer program SAPSA was used to perform a f nite element cynamic analysis, utilizing the response spectrum method.

All wythes in a multlwythe wall were assumed to respond as single wythe walls because of the difficulty in verifying the adequacy of the collar joint between the wythes. This was assumed to be conservative when using the ro-evaluation criteria and the objective of Action item 5 ls to validate the degree of conservatism.

Two double wythe walls (Wall Nos. 24 and GS-D were selected to compare the results obtained from the wall acting either as a single or double wythe wall using the re-evaluation criteria. In using the re-evaluation criterla the walls were assumed to have pinned supports at all appropriate boundsries. As a consequence no forces are induced in the wall due to out-of-plane drift.

The validity of this assumption is addr1ssed in Computech Engineering Services. Inc. Report No. R553.11. Some of the results of Report No. R553.11 are included in this report for the purpose of addressing 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 ano consists of two wythes of six inch wide units. Each wall was analyzed as both a sir.gle and double wythe wall using the same number of nodes, mesh size and boundary conditions. Two boundary conditions were used for each wall; one simply supported on each boundary and the otner fixed. For the fixed boundary condition the out-of-plane drift effects were included as reported in Report No. W3.11.

3 RESlJLTS The results of the analyses performed using the simply supported boundary conditions are Ol ven in Table 1 and 2. Table 1 compares the frequencies of each wall acting either as a single or double wythe wall. Table 2 compares the maximum stress ratlos for each wall acting eittier as a single l I

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or double wythe wall. The valu. , 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 presenwd in Table 1 it is clear that the single wythe assumption is conservative eith 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 wythe.s 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 drift does not induce forces in the walls and the maximum stress ratios given in Table 2 indicate that the maximum stressss in the wali due to other out-of-p!ane 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 1 to 130 percent less than the corresponding single wythe walls. Therefore, for Walls 24 and 65-1 the use of the single wythe assumption to represent double wythe walls 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 conservatNa evaluation with respect to frequency shift and out-of-plane drift wasiderations. The results indicate that the frequency of the double wythc. walls are almost twice those of the equivalent single wythe wall. Therefore, from frequency shift considerations the use of the single wythe assumption is conservative.

The impact on out-of-plane drif t considerations depends on how this is incorporated in the analysis. With the method used in the re-evaluation criteria no forces are Induced in the wall due to out-of-plane drift effects and the maximum stress ratios from other out-of-plane fi tces in the double wythe wall are approximately one-half of those in the single wythe wall. If fixed boundory conditions are used and out-of-plane drif t effects are included, then the maximum stress ratios in the double wythe walls were 1 to 130 percent less than those in the single wythe wall.

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

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TA3LE 1 FREQUENCY OF WALLS WITH SIMPLY SUPPORTED BOUNDARY CONDITIONS Wall No. Thickness Wythos Frequancies (!!z) 12 1 15.39, 37.72 24 25 2 32.06, 78.57 ,

6 1 15.28, 24.99, 43.97 65 -1 g

12 2 30.56, 49.98, 87.95 TABLE 2 MAXIMUM STRESS RATIOS OF WALLS WITH SIMPLY SUPPORTED BOUNDARY CONDITIONS Wall No. Thickness Wythes Mx/Mxa My/Mya 12 1 24

.4057 .1699 25 2 .1809 .0751 6 1 .4834 .1572 65-1 12 2 .2146 .0697 Note: Subscripts x and y denote stress ratios on horizontal and vertical strips respectively 3

- . g 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 0.265 0.228 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 S

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