ML20108F444
| ML20108F444 | |
| Person / Time | |
|---|---|
| Site: | Davis Besse  |
| Issue date: | 11/27/1984 |
| From: | Con V, Triolo S CALSPAN CORP., FRANKLIN INSTITUTE |
| To: | Nilesh Chokshi NRC |
| Shared Package | |
| ML20108F448 | List: |
| References | |
| CON-NRC-03-81-130, CON-NRC-3-81-130 TAC-42903, TER-C5506-163, NUDOCS 8412260354 | |
| Download: ML20108F444 (46) | |
Text
{{#Wiki_filter:_ .-_ _ __ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ Attachnent . TECHNICAL EVALUATION REPORT MASONRY WALL DESIGN TOLEDO EDIS0N COMPANY l DAVIS-EESSE NUCLEAR POWER STATION UNIT 1 NRC DOCKTT NO. 50-346 FRC PROJECT C5506 NRC TAC NO. 42903 FRC ASSIGNMENT 6 NRC CONTRACT NO. NRC-03-81 130 FRC TASK 163 Propanniby Franklin Research Center Author: S. Triolo, V. Con 20th and Race Street Philadelphia, PA 19103 FRC Group Leader: V. Con Preparedfor Nuclear Regulatory Commission Washington, D.C. 20555 Lead NRC Engineer: N. C. Chokshi November 27, 1984 This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, or any of their ernployees, makes any warranty, expressed or implied, or assumes any legal liability or reisponsibility for any third party's use, or the results of such use, of any information, appa-rntus, product or process disclosed in this report, or represents that its use by such third party would not infringe privately owned rights. Prepared by: Reviewed by: Approved by:
,& Y PrirMipal Author:
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. $b f Group Leader T* 8 Wha department DfectM Date: // 7, 4 Date: l ' I '. ':' *h -
Date: I - 2 ') -9 4 FRANKLIN RESEARCH CENTER DIVIslON OF ARVIN/CALSPAN I 20th and Race Streets. Phila.. Pa. 19103 (215) 448 1000
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TER-C5506-163 j l FOREWORD l This Technical Evaluation Report was prepared by Franklin Research Center under a contract with the U.S. Nuclear Regulatory Comunission (Office of Nuclear Reactor Regulation, Division of Operating Reactors) for technical assistance in support of NRC operating reactor licensing actions. The technical evaluation was conducted in accordance with criteria established by the NRC. 4 I y
e TER-C5506-163 i l CONTENTS Section Title Page 1 INTRODUCTION . . . . . . . . . . . . . 1 1.1 Purpose of Revied . . . . . . . . . . . 1 1.2 Generic Issue Background . . . . . . . . . 1 1.3 Plant-Specific Background . . . . . . . . . 1 2 EVALUATION CRITERIA. . . . . . . . . . . . 4 3 TECHNICAL EVALUATION . . . . . . . . . . . 5 3.1 Evaluation of Licensee's Criteria . . . . . . . 5 3.2 Evaluation of Licensee's Approach to Wall Modifications . 21 4 CONCLUSIONS. . . . . . . . . . . . . . 22 5 REFERENCES . . . . . . . . . . . . . . 23 APPENDIX A - SGEB CRITERIA FOR SAFETY-RELATED MASONRY WALL EVALUATION (DEVELOPED BY THE STRUCTURAL AND GEOTECHNICAL ENGINEERING BRANCH [SGEB] OF THE NRC) APPENDIX B - SUM 4ARY OF WALLS REQUIRING MODIFICATIONS APPENDIX C - SKETCHES OF WALL MODIFICATIONS 1 iii
I i i TER-C5506-163
, 1. INTRODUCTION 1.1 PURPOSE OF REVIEW The purpose of this review is to provide technical evaluations of licensee responses to IE Bulletin 80-11 (1]* with respect to compliance with the Nuclear Regulatory Comunission (NRC) masonry wall criteria. In addition, j if a licensee has planned repair work on masonry walls, the planned methods and procedures are to be reviewed for acceptability.
1.2 GENERIC ISSUE BACKGROUND
- In the course of conducting inspections at the Trojan Nuclear Plant, Portland General Electric Company determined that some concrete masonry walls
. did not have adequate structural strength. Further investigation indicated
( that the problem resulted from errors in engineerint judgment, a lack of -{ established procedures and procedural details, and inadequate design 1 l criteria. Because of the implication of similar deficiencies at.other I operating plants, the NRC issued IE Bulletin 80-11 on May 8, 1980. 4 IE Bulletin 80-11 required licensees to identify plant masonry walls and l their intended functions. Licensees were also required to present reevaluation i i i criteria for the masonry walls with the analyses to justify those criteria, j If modifications were proposed, licensees were to state the methods and
! schedules for the modifications.
i 1.3 PLANT-SPECIFIC BACKGROUND l i In response to IE Bulletin 80-11, Toledo Edison Company provided the NRC with documents (2-6] describing the status of masonry walls at Davis-Besse j Unit 1. The information in these documents was reviewed, and a request for 1 additional information was sent to the Licensee on March 8, 1982, to which the I Licensee responded (7, 9). As the result of a meeting between Toledo Edison and members of the NRC staff on May 27, 1982 and the combined technical i
- Numbers in brackets indicate references, which are cited in Section 5.
j :
l l l TER-C5506-163 meeting and site visit of June 21-23, 1983, additional questions were sent to the Licensee, to which it has responded (8, 13]. In Reference 6, the Licensee reported 169 safety-related masonry walls at Davis-Besse Unit 1. The main functions of these walls include fire and flood barriers, radiation shielding, and negative pressure boundaries. Also, the walls support minor platforms, piping, conduit, and instrumentation. No masonry walls were designed to act as shear walls. Masonry walls at the plant are typically hollow unit construction (three cells) , laid in a stack bond, partially or fully grouted, and vertically reinforced. The stack bond construction is not cosmonly used in nuclear plants, and exclusive use of stack bond construction is found at this plant. Both single- and double-wythe walls are found. The properties of the materials used in construction, according to Reference 4, are as fol'.ows: reinforced masonry (fully grouted) - f's = 1500 psi reinforced masonry (partially grouted or hollow) - f's = 1350 psi vertical reinforcing - fy = 40,000 psi horizontal reinforcing - Dur-o-Wal extra heavy truss type, fy = 65,000 psi i Reference 6 stated that 28 walls required structural modification involving the addition of steel braces and the reinforcing of boundary connections with angles and bolts. The Licensee has relied upon the energy balance technique to ciualify 75
- masonry walls, 16 of which are among the modified walls mentioned above. NRC, FRC, and FRC's consultants (Drs. H. Earris and A. Basid of Drexel University) have conducted an exhaustive review of this subject based on submittals provided by the Licensee and published literature and have concluded that the available data in the literature do not give enough insight for understanding j the mechanics and performance of reinforced masonry walls under cyclic, fully reversed dynamic loading. As a result, a meeting with representatives of the affected plants was held at the NRC on November 3, 1982 so that the NRC and FRC's staff and consultants could explain why the applicability of the energy balance technique to masonry walls in nuclear power plants is questionable 113). In a subsequent meeting on January 20, 1983, consultants of utility companies presented their rebuttals [14) and requested that they be treated on a plant-by-plant basis.
1 ._ _ _ , . -_ - - - - -- .____ _ - . . .. -
TER-C5506-163 In accordance with the above request, NRC, FRC, and consultants visited several nuclear power plants, including Davis-Besse Unit 1 on June 21 through 23, 1983, to examine the field conditions of masonry walls in the plants and to gain first-hand knowledge of how the energy balance technique is applied to actual walls. Further discussion on this subject is provided in Section 3.1. j .l I ' l
. . .. . - - . ~ - _ . - . - _ , . . - _ _ - - , - -- , _ _ , _ - -- -. --_ . _ _ - - - - _ . - .
TER-C 5506-163 -
- 2. EVALUATION CRITERIA The besic documents used for guidance in this review were the criteria developed by the Structural and Geotechnical Engineering Branch (SGEB) of the NRC (attached as Appendix A to this report), the Uniform Building Code [10),
and ACI 531-79 [11). The materials, testing, analysis, design, construction, and inspection of safety-related concrete masonry structure should conform to the SGEB criteria. For operating plants, the loads and load combinations for qualifying the masonry walls should conform to the appropriate specifications in the Final Safety Analysis Report (FSAR) for the plant. Allowable stresses are specified in Reference 11 and the appropriate increase factors for abnormal and extreme
- environmental loads are given in the SGEB criteria (Appendix A),
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I J f TER-C5506-163 d
- 3. TECHNICAL EVALUATION -
i ! I
- This evaluation is based on the Licensee's earlier responses (2-6) and l subsequent responses (7, 8, 9,12] to the NRC requests for additional information. The Licensee's criteria were evaluated with regard to design and
~
analysis methods, loads and load combinations, allowable stresses, construc-tion specifications, materials, and any relevant test data. 3.1 EVALUATION OF LICENSEE'S CRITERIA 4 l The Licensee evaluated the masonry walls using the following criteria: i o Allowable stresses for service loads are based on the Uniform Building Code of 1970. o The working stress design method and energy balance technique were used to qualify the walls. Of 169 safety-related walls, 75 have been qualified by the energy balance technique. 4
- o Damping for unreinforced walls
24 for operating basis earthquake (OBE) and safety shutdown earthquake (SSE) o Damping for reinforced walls: 24 for OBE 44 for SSE o when the natural frequencies of the walls are on the lower side of the , peak floor response spectra, this peak value was used in obtaining the inertial loading. o A typical analytical procedure used in the working stress design method is susumerized below. i
- determine wall boundary conditions (pinned or free)
- calculate the wall's fundamental frequency using either a one-way 4
vertical or one-way horizontal action assumption
- obtain inertial loading from average floor response spectrum (If the i fundamental frequency of the wall is on the lower side of the peak floor response spectra, the peak value was selected to obtain the inertial loading.)
- compare computed stresses with the allowable values. l l
- o A typical analytical procedure used in the energy balance technique is l i
summarized belows i l l l _ - . __ _ _ _ . . ~ . _ . _ . _ _ . _ __ __ __ ._-_ ---__ _.___ _ _ _ _ - - - - _ . _ _ _ _ _ - - _ _
TER-C5506-163 I determine the applied moment l determine the yielding moment
)
obtain the ductility ratio (based on the formula given in Response 11 and compare it with the allowable ductility ratio of 5 check the compressive stress of the masonry and compare with the allowable of 0.85 obtain the deflection of the wall (based on the formula given in . Response 11) and check if it affects any safety-related items. The Licensee's criteria [4] and responses (7, 8, 9, 12] have been reviewed. Other than those areas identified in Section 4, the Licensee's criteria have been found to be adequate and in compliance with the SGER , criteria (Appendix A) . Following is an review of the Licensee's responses [7, 9] to the NRC's original qJestions as well as the responses (8,12] to questions that arose - from the meeting of May 27, 1982 and the combined meeting and site visit of June 21-23,1983. . Question 1 Table I [4] refers only to the edge conditions as indicated in the masonry wall drawings. Provide the boundary conditions assumed for the analysis. Response 1
- The Licensee responded that, in walls that were analysed as vertical strips, the top and bottom edges have been assumed pinned unless the wall is free at the top, in which case the bottom is fixed. (See Response No. 26 for further details.) In walls that were analyzed with horisontal spans, the sides were assumed pinned.
A typical base connection consists of Phillips Red Need Self Drilling Anchors in the concrete slab, with 24-in-long threaded bars in the anchors, at each vertical reinforcement. The method of analysis is judged to be adequate.
- Question 2 j Indicate how the effects of higher modes were considered in cases where the analysis was based on the "SLOCK WALLS" program, which includes only three modes.
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.TER-C5506-163 Response 2 l
In this response, the Licensee stated that the computer code " BLOCK l MALLS" was verified by comparison with a nine-mode solution and the difference i was only 1.1% in the wall's responses. As has been seen in other plants, the first mode usually contributes 95% or higher to the response. For all
' practical purposes, the responses resulting from the first three modes should l
j be adequate and in compliance with the SGES criteria. 1 1 l Question 3 i Indicate whether any of the walls was analyzed as a plate, with special reference to walls having cut-outs. a Response 3 l I This response indicated that some masonry walls were analyzed using the 1 finite element computer code BSAP. The size of the finite element mesh was 1
! influenced by the height and length of wall, location and number of applied
] loads, size and cost of the model created, and the spacing of reinforcing. ] openings larger than the selected mesh size were included in the model, ] smaller ones were not. l The review of some calculations during the meeting on June 21 through 23, 1983, indicated that the mesh size used in the finite element model was j reasonable adequate, and large openings were adequately accounted for in the I model, t Question 4 (from meetines on June 21, 22, and 23,1983) Clarify and justify the use of I ef fective/t effective or I uncracked/t uncracked in the calculations of well No. 2297, where: I effective = effective moment of inertia t effective = effective thickness of the section used in the analysis i I uncracked = uncracked moment of inertia t uncracked = thickness of the uncracked section used in the analysis. i i l Response 4 (Reference 121 l Wall 2297 is a double-wythe wall consisting of two 8-in wythes, separated I 7 l l.
l l - l l TER-C5506-163 by 2 inches of concrete fill. The wall was originally analyzed as two independent 8-in walls (single-wythe) using the BLOCK WALLS computer program and a maximum ductility ratio of 2.07 (qualified based on energy balance technique). Bowever, the steel floor beam on top of the wall was overstressed; therefore, a modification was required. For the purpose of designing the proper modification, the wall was reanalysed assuming a complete thickness of the wall (composite section). The BSAP dynamic run was performed to obtain the natural frequency of the wall using I effective (which is function of I cracked and I uncracked); assuming the applied moment is equal to the yield moment, this results in a minimum natural frequency and a maximum acceleration. This acceleration is then used as input for the BSAP static run to determine stresses and reactions. The stress of the steel floor beam with modification (addition of braces to the beam) was then checked. The method of using I effective and the application of yield moment is reasonably adequate for designing the modification. Question 5 Explain why the Table V (4) factors for operating basis earthquake (OBE) and wind load are 1.0, while the plant FSAR specifies a factor of 1.25 for these loads. Response 5 (Reference 71 This response explained that the FSAR load factor of 1.25 for OBE and wind loads was based on the ultimate strength method of analysis,"whereas the factor of 1.0 in Table v [4] is for the working stress method. This response is satisfactory and is consistent with the SCEB criteria. Question 6 (from the meetings on June 21, 22, and 23,1983) Provide a summary of walls which have to be qualified by an increase in allowable stresses for OBE load combinations. Indicate actual calculated stresses and allowable stresses. Justify the increase in allowable stress. I 1
J . TER-C5506-163 Response 6 [ Reference 12) The Licensee responded that four walls were qualified on the basis of allowable stresses that had been increased by 1.25 for load combinations containing OBE loads. A table was provided, giving the actual steel and masonry stress in each of these four walls as well as the factored and unfactored allowable stresses. The four walls and the percentages by which the actual steel tensile stresses exceed the unfactored allowables ares l 3016 12.5% j 3198 13.0%
- 5137 23.0%
4026 14.0% The SGEB criteria do not permit an increase in allowable stress for load l combinations containing OBE loads. However, the Licensee made assumptions that compensate for the increase factor. The Licensee used a constant
- response floor response spectra, equal to the peak response for natural j frequencies on the low frequency side of the peak and low damping (2% for OBE j and 44 for SSE) in the analysis. Also, the four walls in question were l
l analyzed using one-way simple spans (vert'ical for 3016 and 4026 and horizontal 4 for 3198 and 5137) . These assumptions will yield a conservative estimate of stress values. Because of this, the Licensee's response is acceptable with
! respect to the SGEB criteria.
) i Question 7 Indicate how equipment weight was considered in the analysis of the masonry walls. Standard Review Plan (SRP), Section 3.7.2, suggests that the equipment weight should be multiplied by a factor of 1.5 times the peak floor acceleration. i j Response 7 , This response states that the SRP factor of 1.5 refers to an equivalent j static analysis, and since all masc.nry walls at Davis-Besse Unit I were analyzed with a dynamic method which includes the weight of the wall and
- equipment, a factor of 1.5 was not appropriate.
4 1
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TER-C5506-163 Since the equipment weight was included in the dynamic analysis, the concern about the factor of 1.5 is no longer applicable in this case. Question 8 With reference to Section 7.1, Appendix E [4), use the envelope of the floor spectra or provide justification for using the average spectral acceleration. I Response 8 The Licensee showed analytically that the use of the average response spectra is more appropriate than the conservative approach of using the j envelope of the floor response spectra. Using an example of an undamped simply supported beam, it is shown that the absolute maximum modal dislacement response is less than or equal to the value obtained by using the average of - spectral values corresponding to the two supports. Also, the use of the l average response spectra is considered satisfactory because of the ! conservative method of determining responses a constant response, equal to the peak response, is used on the low frequency side of the peak. The Licensee's response is satisfactory. Question 9 with reference to Table II [4], indicate possible variations in the value E for masonry, and determine the actual value of E such that the spectral curve provides a conservative estimate for acceleration. Response 9 In this response, the Licensee stated that a value of E of 1000 f's, based on the 1970 Uniform Building Code and ACI 531-79, was used. Since the floor response spectrum employed a constant response equal to the peak response for frequencies on the low frequency side of the peak, this value of E should be adequate. 1
k 4 TER-C5506-163 ! 4 Question 10 With reference to page 8 of Reference 4, provide sample calculations to-
- illustrate that single-wythe analysis of multiple-wythe walls is conservative.
Response 10 f j In response to this question, the Licensee performed an analysis of two double-wythe walls using a single-wythe and double-wythe assumption for each. The results obtained from the single-wythe analysis were compared to the results obtained from the double-wythe analysis; this was done for each wall (1177 and 2107). The results of these analyses were shown in terms of frequencies, moments, and tensile steel stresses. The results indicate that the frequencies of the double-wythe wall are greater than those of the single-wythe walls and that the mor.ents and tensile steel stress ratios are t much smaller in the double-wythe wall. The single-wythe assumption applied to I multiple-wythe masonry walls is considered conservative and in compliance with the SGEB criteria. i. Question 11 It is the NRC's position that the energy balance technique and the arching theory should not be used in the absence of conclusive evidence of their validity as applied to masonry structures. With reference to Table I (4), explain the following points:
- a. Provide sample calculations to show the procedure used to j determine the ductility ratio of walls and explain the effect of
- wall boundary conditions on the this ratio.
] b. Explain why the ductility ratios for several walls are less than unity even though the working stresses have been exceeded.
- c. Explain how a ductile mode of failure of the masonry walls can be j guaranteed since it depends on several factors, such as the j amount and distribution of reinforcements and the anchorage
, provided. l ! d. Explain how wall deflections are estimated for specific ductility ! + ratios. ) i _.-. _ ... _ . - _ __ _ _ _ - _ _ _ _ . _ - _ .~ .- --__ . _ - - _ _ _ _ .__ _ _ .. .
.. . -= .,. - . - - - _. -- . _ -
a . 1 1 TER-C5506-163 I i , o i Response 11 i The Licensee responded to the four points raised in this question as . l follows
- a. The Licensee provided the following equation used to determine the ductility ratio:
y=f[1+(')] - ! where Ma = applied moment My = yield moment This formula was developed based on the energy balance technique used in a single degree of freedom system where the material is assumed to . have an elastic, perfectly plastic behavior,
- b. It was stated that a ductility ratio less than unity simply means -
that the stress in the reinforcing bar falls below yield stress level.
- c. The Licensee cited several references that support the assumption of I
a ductile mode of failure in masonry walls. Reference 16 observes the flexible behavior of masonry structures within 20 miles of the epicenter of an earthquake; Reference 17 indicates significant ductility in walls having a reinforcement ratio greater than 0.154 (all masonry walls at Davis-Besse Unit I have reinforcement ratios that exceed this value); Reference 18 indicates that a masonry wall is a ductile structure when a flexural type of failure will occur l with tensile yielding in the reinforcing steel. I
- d. The equation by which masonry wall defections were calculated was given as follows:
l A, = A x h x p x 2 ' i where Fy = yield stress of reinforcing bar fs = calculated stress of reinforcing bar A = calculated deflection 2 = factor of safety NRC staf f, FRC, and FRC's consultants have conducted an exhaustive review of available information on the energy balance technique and of the Licensee's responses to determine the technical adequacy of the methodology. In addition,
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TER-C5506-163 a site visit and a meeting were held with Davis-Besse Unit 1 representatives on June 21 through 23, 1983 to examine the as-built conditions of the walls and to review the analytical procedures and specific calculations regarding this subject. FRC and its consultants have issued their evaluation and assessment of the use of the energy balance technique for masonry walls [13,15). The Structural and Geotechnical Engineering Branch (SGEB) has issued a position statement regarding this subject which will be addressed in its safety Evaluation Report. j The following walls have been qualified by the energy balance technique 2057, 2067, 2147, 2167, 2427, 3417, 5017, 5147, 5107, 5197, 4867, 6107, 1237, 3357, 1348, 2107, 2267, 3297, 3367, 2077, 1038, 1157, 3277, 4917, 5127, 5157, 5277, 6087, 2247, 2317, 2447, 3267, 5367, 305D, 307D, 313D, 1197, 2018, 2227, 2257, 2277, 3257, 3347, 3397, 2371, 3040, 1087, 1147, 2237, 2367, 3227, 4046, j 1227, 1267, 1337, 1428, 2087, 2177, 311D, 3036, 3307, 3167, 3177, 3187, 3287, 5107, 2337, 4016, 4036, 4796, 4886, 4896, 3407, and 4647. 1 i
; Question 12 (from meeting on May 27, 1982) i i
- Provide additional information, as discussed in our meeting, to support
- the use of our energy balance technique for the masonry wall evaluation
! (schedule for submittal of this information will be provided by 6/4/82). I Response 12 (Reference 81 I To further substantiate the applicability of the energy balance technique to masonry walls, the Licensee referred to full scale tests performed by J. C. Scrivener and the SCACI-SEAOSC Task Committee on Slender Walls. i scrivener tested an 8-f t ll-in high wall and partially grouted walls constructed of 4-in hollow bricks reinforced with a 1/2-in diameter bar at approximately 18 in on centers. The test results indicated that a ductility { ratio in excess of 10 can be achieved. i . The SCACI-SEAOSC Task Committee on Slender Walls tested 4-f t-wide by l l 24-f t-high walls constructed of 6 , 8 , and 10-in block reinforced with five 1 r
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TER-C5506-163 Nc. 4 bars. The minimum deflection of failure of any of the nine walls tested 1 was 7.1 in, indicating a minimum ductility of 10. As stated in the review of Response 11 above, FRC and its consultants have issued their evaluation of the use of the energy balance technique [13, 15), and the SGEs has issued a position statement which will be addressed in its safety Evaluation Report.
- Question 13 I
With reference to Table IV [4), specify the allowable stresses for shear (shear walls and flexural members where reinforcement takes the shear), } tension parallel to the bed joint, and tension normal to the bed joint. 4 Response 13 The Licensee responded that no masonry walls were built to resist 3 building shear, and in no case was reinforcement relied upon to resist shear, i l since the maximum masonry shear stress for every wall was under 0.02 f's. ! Also, all tension parallel and normal to the bed joint was taken by reinforcements so the allowable masonry tension parallel and normal to the bed I joint was sero. This response satisfies the SGEs criteria. Question 14 4 With reference to Table IV [4], justify the maximum value of 1200 psi l specified for allowable stress in axial compression. t Response 14
- The Licensee responded that the value of 1200 poi for allowable stress in l
aatal compression is obtained from the 1970 Uniform Building Code and corresponds to an f's of 6000 psi. However, this value was not used for ( Davis-Besse Unit 1. The values established for f's at Davis-Besse Unit 1 are 1500 psi for reinforced-fully grouted or solid units and 1350 psi for ! reinforced-partially grouted or hollow units. These values result in maximum
)
TER-C 5506-163 allowable masonry axial compression values of 300 psi and 270 psi, respectively, which are the allowables for Davis-Besse Unit 1. The Licensee's maximum allowable values for masonry axial compression stress are in compliance with ACI $31-79 and are therefore acceptable. Question 15 with reference to the proposed allowables for factored loads in Table IV (4), justify the increase factors of 3.17 for bearing, 1.5 for masonry shear, 1.67 for reinforcement shear, and 1.33 for bond. The SGEB criteria [4] propose 2.5 for bearing,1.3 for masonry shear, and 1.5 for reinforcement shear. Response 15 In this response, the Licensee indicated that the factors used to obtain the stress allowables for bearing stress from the allowables in ACI 531-79 is 2.5. This value is in compliance with the SGEB criteria. Regarding the factors for masonry shear and reinforcement shear, the Licensee stated that these increase factors were never used in the analysis (masonry shear was within the allowable for OBE case) and the only ultimate stress allowables that had to be used were 0.85 f's for masonry compressive stress due to flexure and 0.9 Fy for tension in reinforcement. These values are in compliance with the SGES criteria. ] Question 16 with reference to Table IV (4), justify the value for maximum allowable compression for reinforcement since it exceeds the ACI 531-79 maximum of 24,000 psi [11]. Response 16 This response stated that no masonry wall used reinforcement to resist compressive loads. Therefore, this question is not applicable. 4 1
TER-C5506-163 - Question 17 Provide details of proposed wall modifications with drawings, and indicate how these modifications will help to correct the wall deficiencies. Indicate how out-of-plane drift effects due to bracing are considered in the analysis.
! Response 17 The Licensee provided details of wall modifications, which included the ; addition of structural steel braces and steel angles at the edges to reinforce the boundary conditions (see Appendix 5 for sketches of typical modifications) .
The original assumptions concerning boundary conditions (see Response 1) were not changed by the modifications, and since all walls, except cantilevered walls, were pinned at the boundaries, no significant out-of-plane drif t , i effects are expected. Appendix B provides a summary of walls which required modifications. . Question 18 (from meeting of May 27, 1982) Provide the number of modified walls which are not meeting working stress criteria. l
- Response 18 [ Reference 8]
The Licensee stated that af ter the modifications were completed,16 of the modified walls were qualified by the energy balance technique and not by
- the working stress criteria. The affected walls are 311D, 3036, 3307, 3167, 3177, 3187, 3287, 5107, 2337, 4016, 4036, 4796, 4486, 4096, 3407, and 4447
; ' see the review of Response 11 for comments concerning the applicability l of the energy balance technique to assonry walls.
J Question 19 (f rom poeting of May 27. 1982) Discuss the applicability of Branson's equation to calculate I , which was originally developed for reinforced concrete structures, to masonry walls. Applicability of this equation should be substantiated by ! comparison of results using this equation to the available results of a test program (i.e., recently completed SEAOCS tests) . l l l l ! { l , s.- _ ____ _ ._
l i TER-C5506-163 i Response 19 (Reference 8] In this response, the Licensee substantiated the use of Branson's equation by comparing test results performed by J. C. Scrivener for wall deflections to calculated results. Materials properties reported by J. C. Scrivener were used to calculate Io (effective moments of inertia) using 3ranson's equation, which were in turn used to calculate deflections. A simply supported test wall was used for the comparison and the following table provides the results. Test Load Test Deflection Calculated Deflection (1b/ft 1 2 (in) (in) 50 0.33 0.38 80 0.54 ,,. 0.76 120 1.05 1.21 j 130 1.20 1.31 As can be seen from the above table, the deflections calculated using 4 Branson's equation were consistently higher than the test deflections; therefore, the use of Branson's equation is conservative and appropriate. Question 20 (from meeting on May 27, 1982) Discuss the modulus of rupture values used as inputs to the " BLOCK WALLS" program. Indicate the types of analysis (i.e., horizontal or vertical strips) to which these values are applicable. , i Response 20 (Reference 81 For horisontal spans, the modulus of rupture was assumed to be sero. For
; frequency calculations of vertical spans, the concrete fill was the only material assigned a modulus of rupture. The modulus of rupture for fully grooted blocks was calculated as follows:
fr = 6M , where f'c = 2500 pai (concrete fill)
; fr ='300 psi
, This response is adequate and consistent with SGEB criteria. 'l
- j TER-C5506-163 Question 21 (from meeting on May 27, 1982)
There appears to be computation error in Appendix F of the November 1980 submittal [4] (the value of 1096.22 in4 appears to be high for a l
! , cracked wall) . Confirm that this is an illustration example only and does not represent any walls at your plant.
Response 21 [ Reference 8) The Licensee explained that the computer code " BLOCK WALLS" prints a statement if the wall cracks and does not print a statement if the wall does i not cracks therefore, the value of 1096.22 in for moment of inertia on page 9 of Appendix F [4] is correct, since the example wall does not crack. Also, there is a typographical error in Section 3.2 F of Appendix F: the input of the seismic moment in the equation for tension should' be 24.79, not 26.79. . It was confirmed that the computation for the masonry wall in Appendix F (4] was an example and does not represent any walls at Davis-Besse Unit 1. This response is satisfactory. - Question 22 (from meeting on May 27, 1982) l Provide the details of the horizontal reinforcement in the walls and explain how it was treated in the analysis. Response 22 [ Reference 81 The Licensee provided the following pattern of horizontal reinforcements 8-inch thick walls . first 5 bed joints - 10 8 extra heavy Dur-O-Wal l sixth bed joint - 2 0 4 extra heavy Dur-0-wal (placed side by side) { i 12-inch thick walls -- first 5 bed joints - 10 12 extra heavy Dur-O-Wal sixth bed joint - 20 6 extra heavy Dur-O-Wal (placed side by side) i These patterns repeat for the full height of the wall. Calculations made for comparison show that two Dur-O-Wals placed side by side result in larger section properties than a single Dur-O-Wal and, there-fore, in higher natural frequencies and lower accelerations. For analyses l l l _ , , . - . _ _ - _ _ . - . . , _ _ . . _, ._-,______--m-_ , . . . . . . _ . . . - , . _ _ . _ ~ _ _ _ . _ _ _ _ , - . _ . . _ _ _ _ , _ _ _ _ _ _ _ , . _ _ _ . _ , , , _ _ , . _ . _ . _ _. , _ _ ,
. . _ __ ._ _ _ _._ _ - _ . ___._ ..m._ .
TER-C5506-163 I using horizontal spans, only one Dur-o-Wal was assumed in each joint for the j full height of the walls this assumption will provide conservative results. The Licensee used a maximum allowable tensile stress of 30',000 psi for Dur-O-Wal. 4 4 This response is acceptable under the SGEB criteria. ! Question 23 (from meeting on May 27, 1982) Provide pre-modifications and post-modification calculations for wall No. j 3167. t I Response 23 [ Reference 8) I The Licensee provided the requested calculations for wall 3167.
- Modifications to this wall consisted of steel braces which reduced the wall to l a series of shorter spans (see Appendix C for further details) . However, even with these modifications, the masonry reinforcement was overstressed in j tension, under the working stress criteria. Therefore, the energy balance j technique was used, with the modifications, to qualify wall 3167.
i Question 24 (from meetings on June 21, 22, and 23,1983) 1 Verify that for walls 3447, 3457, and 3467, the only safety system affected by wall failure would be the NVAC duct as assumed in the calculations, j Response 24 [ Reference 12] The Licensee indicated that further review verified the HVAC duct as the 1 l only wall attachment affected by walls 3447, 3457, and 3467. However, the HVAC duct is not nuclear safety-related this is stated in the calculations
; for walls 3447, 3457, and 3467, but was misinterpreted during the meeting.
This response is satisfactory. ! Question 25 (f rom meetings on June 21, 22, and 23,1983) 4
- Provide the basis for not performing a displacement / operability check for safety systems attached to wall qualified by the ductility values of less than 3.0.
1 l
TER-C5506-163 Response 25 (Reference 121 In this response, the Licensee stated that, if a deflection criterion of l L/240 were used, a corresponding ductility ratio of 2.7 to 3.3 would be produced in masonry walls such as those found'at Davis-Besse Unit 1. Bowever, most walls at Davis-Besse Unit 1 that were analyzed by the energy balance i technique were analysed using the "3 LOCK WALL 8" progan which conservatively overestimates wall deflections. The Licensee felt that because of this conservatism a ductility criterion was more appropriate than a deflection criterion for walls accepted by the "3 LOCK MALLS" program. This response is satisfactory: however, see the review of Response 11 for comments concerning walls qualified by the energy balance technique. Question 26 (from meetings on June 21, 22, and 23, 1983) Justify the assumption of fixed boundary condition in some situations by examining a typical connection detail where this assumption is used. Assess the impact of joint flexibility on calculated results. l 1 , Response 26 (Reference 12) I The Licensee responded that, in a review of cantilevered walls (assumed
; fixed at the base) in which appropriate spring constants were used for the components of the boundary connections, it found that lower frequencies f
resulting from an increase in flexibility did not result in masonry or reinforcement stresses higher than the allowables. Also, the affected walls have one or more supported boundaries in addition to the fixed base that were l l not considered in the analysis. l A typical base connection consists of Phillips Red Head Self Drilling Anchors in the concrete slab, with 24-in-long threaded bars in the anchors, at each vertical reinforcement. The Licensee concluded that an increase in flexibility would not af fect the acceptance of cantilevered walls in which a fixed boundary was assumed. 3ased on the information provided by the Licensee, this review concurs with the Licensee's conclusions the assumption of a fimod boundary is reasonably appropriate.
9 9 TER-C5506-163 3.2 EVALUATION OF LICENSEE'S APPROACH TO WALL MODIFICATIONS According to Reference 6, 39 walls (including three walls mentioned in Response 24 of Section 3.1) did not meet the acceptance criteria. Eight of these walls will be removed and three were found acceptable upon further
- evaluation of the consequences of their failure (see Appendix B for further details). The remaining 28 walls were scheduled for structural modifications consisting primarily of the addition of external steel braces and the reinforcing of boundary connections with bolted angles. Reference 9 indicated that the modifications were scheduled for completion by November 1983.
Of the walls being modified, 16, were qualified by the energy balance technique after modifications. See Sections 3.1 and 4.0 for comments on the use of the energy balance technique to qualify masonry walls. The Licensee provided sample calculations and details for wall
- modifications. The Licensee's approach to wall modifications has been reviewed and, with the exception of the use of the energy. balance technique, has been found to be adequate and consistent with the SGEB criteria. See Appendix B for examples of wall modifications.
4 i 4 1
TER-C5506-163 -
- 4. CONCLUSIONS A detailed study was performed to provide a technical evaluation of the masonry walls at Davis-Besse Nuclear Power Station Unit 1. Review of the Licensee's criteria and additional information provided by the Licensee led to the conclusions given below.
The Licensee's criteria have been found technically adequate and in compliance with the SGEB criteria except for the following areast o An increase of 25% in allowable stress was used for load combinations containing OBE loads. The following four walls required this increase in order to be qualified: 3016, 3198, 5137, and 4026. The SGEB criteria do not permit an increase in allowable stress where OBE loads are concerned; however, the Licensee employed several conservatisms in its computation of stress values that offset the increase factor for allowables. The Licensee used a constant response floor response sp4ctra, equal to the peak response for natural frequencies on the low ' frequency side of the peak. Also, the walls in question were analyzed as one-way, simply supported beam strips. Because of the conservative stress values which these assumptions produce, it can be concluded that the Licensee's increase factor is acceptable and meets the intent of the SGEB criteria. o with regard to the energy balance technique, the following walls were affected: 2057, 2067, 2147, 2167, 2297, 2427, 3417, 5017, 5147, 5187, 5197, 4867, 6107, 1237, 3357, 1348, 2107, 2267, 3297, 3367, 2077, 1038, 1157, 3277, 4917, 5127, 5157, 5277, 6087, 2247, 2317, 2447, 3267, 5367,' 305D, 307D, 313D, 1197, 2018, 2227, 2257, 2277, 3257, 5347, 3397, 2371, 304D, 1087, 1147, 2237, 2367, 3227, 4046, 1227, 1267, 1337, 1428, 2087, 2177, 311D, 3036, 3307, 3167, 3177, 3187, 3287, 5107, 2337, 4016, 4036, 4796, 4486, 4896, 3407, and 4647. ( As stated in the review of Response 9 [7], FRC and its consultants have issued their assessment of the use of the energy balance technique in the analysis of masonry walls in nuclear power plants. The Structural and Geotechnical Engineering Branch (SGEB) has also issued a position statement on this subject, which will be addressed in its safety Evaluation Report. n t t l
TER-C5506-163 l l
- 5. REFERENCES l
- 1. IE Bulletin 80-11
" Masonry Wall Design" NRC, 08-May-80
- 2. R. C. Crouse Letter to J. G. Keppler, NRC.
Subject:
Delay in Response to IE Bulletin 80-11 for Davis-Besse Nuclear Power Station Unit No. 1 Toledo Edition, 30-Jun-80 Serial No. 1-149
- 3. R. C. Crouse Letter to J. G. Keppler, NRC.
Subject:
Response to Items 1, 2a and 3 of IE Bulletin 80-11 for Davis-Besse Nuclear Power Station Unit No. 1 Toledo Edition,14-Jul-80 Serial No. 1-150
- 4. R. C. Crouse Letter to J. G. Keppler, NRC.
Subject:
Response to Item 2b and expanded response to Item 3 of IE Bulletin 80-11 for Davis-Besse Nuclear Power Station Unit No.1 Toledo Edition, 04-Nov-80 Serial No.1-169
- 5. R. C. Crouse Letter to J. G. Keppler, NRC.
Subject:
Delay in Completing Re-evaluation required by IE Bulletin 80-11 Toledo Edition, 15-May-81 Serial No. 1-200
- 6. R. C. Crouse Letter to J. G. Keppler, NRC.
Subject:
Final Report for IE Bulletin 80-11 (Attached) Toledo Edition, 29-Sep-81 , , Serial No. 1-217
- 7. R. C. Crouse Letter to J. F. Stolz, NRC.
Subject:
Response to Request for Additional Information Concerning Masonry Wall Design - IE Bulletin 80-11 . Toledo Edition,16-Jun-82
- 8. J. Ray Letter to A. De Agazio, NRC.
Subject:
Response to Action Items on NRC IE Bulletin 80-11 Resulting From May 27, 1982 Meeting in Bechtel Gaitersburg Office Toledo Edition, 23-Jun-82 (
1 l TER-C5506-163
- 9. R. C. Crouse Letter to J. F. Stolz, NRC.
Subject:
Schedule for Completion of Masonry Wall Modifications - IE Bulletin 80-11 Toledo Edition,14-Jul-82 4
- 10. Uniform Building Code International Conference of Building officials,1979
- 11. Building Code Requirements for Concrete Masonry Structures Detroit: American Concrete Institute,1979 _
ACI 531-79 and ACI 531R-79
- 12. R. P. Crouse Letter to J. F. Stols, NRC
Subject:
Response to Action Items Resulting From Meetings of June - 21, 22, and 23, 1983 Toledo Edison,19-Aug-83
- 13. H. G. Harris and A. A. Hamid,
" Applicability of Energy Balance Technique to Reinforced Masonry Walls" Dept. of Civil Engineering, Drexel University August 1982
- 14. Computech Engineering Services Inc., URS/ John Blume and Associates, and Bechtel P:nter Corporation
" Rebuttal to ' Applicability of Energy Balance Technique to Reinforced Masonry Walls' by Harris and Basid,"
February 1983
- 15. A. A. Hamid, H. G. Harris, and V. Con
" Evaluation of the Applicability of Energy Balance Technique to Masonry Walls in Nuclear Power Plants" Franklin Research Center July 1983
- 16. H. J. Degenkolb *
" Structural observations of the Kern County Earthquake" ASCE Transactions, Paper No. 2777 August 1953 l
l
- 17. Sheppard et al.
"The Influence of Horizontally Placed Reinforcement on Shear Strength and Ductility of Masonry Walls," 6th International World l Conference on Earthquake Engineering,1977 l
- 18. J. C. Scrivner-
" Reinforced Masonry - Seismic Behavior and Design," Bulletin New Zealand Society for Earthquake Engineering, Vol. 5, No. 4 December 1972
J APPENDIX A N SGEB CRITERIA FOR SAFETY-RELATED MASONRY WALL EVALUATION (DEVELOPED BY THE STRUCTURAL AND GEOTECHNICAL ENGINEERING BRANCH [SGEB] OF THE NRC) i l l i FRANKLIN RESEARCH CENTER DIVISION OF l eCAL 5 PAN 20thand Race Streets l Philadelphia, PA 19103 l
TER-C5506-163 CONTENTS Section Title Page 1 GENERAL REQUIREMENTS . . . . . . . . . . . A-1 2 LOADS AND LOAD COMBINATIONS. . . . . . . . . . A-1
, a. Service Load Combinations . . . . . . . . . A-1
- b. Extreme Environmental, Abnormal, Abnormal / Severe Environmental, and Abnormal / Extreme Environmental Conditions . . . . . . . . . . . . . A-2 I
3 ALLOWABLE STRESSES . . . . . . . . . . . . A-2 4 DESIGN AND ANALYSIS CONSIDERATIONS . . . . . . . . A-3 5 REFERENCES . . . . . . . . . . . . . . A-4 I l iii l l I i
TER-C5506-163
- 1. General Requirements i The materials, testing, analysis, design, construction, and inspection related to the design and construction of safety-related concrete masonry walls should conform to the applicable requirements contained in Uniform Building Code -.1979, unless specified otherwise, by the provisions in this criteria.
The use of other standards or codes, such as ACI-531, ATC-3, or NCMA, is also acceptable. However, when the provisions of these codes are less conservative than the corresponding provisions of the criteria, their use should be justified on a case-by-case basis. In new construction, no unreinforced masonry walls will be permitted. For operating plants, existing unreinforced walls will be evaluated by the provisions of these criteria. Plants which are applying for an operating license and which have already built unreinforced masonry walls will be evaluated on a case-by-case basis.
- 2. Loads and Load Combinations The loads and load combinations shall include consideration of normal loads, severe environmental loads, extreme environmental loads, and abnormal loads. Specifically, for operating plants, the load combinations provided in the plant's FSAR shall govern. For operating license applications, the following load combinations shall apply (for definition of load terms, see SRP Section 3.8.4II-3) .
(a) Service Load Conditions (1) D+L (2) D + L + E (3) D+L+W 1 If thermal stresses due to To and Ro are present, they should be ) included in the above combinations as follows: , (la) D + L + To + Ro (2a) D+L+To+Ro+E (3a) D + L + To + Ro + W Check load combination for controlling condition for maximum 'L' and for no 'L'. l 1 l A-1
TER-C5506-163 (b) Extreme Environmental, Abnormal, Abnormal / Severe Environmental, and
~
Abnormal / Extreme Environmental Conditions j (4) D + L + To + Ro+E (5) D + L + To + Ro+Wt (6) D + L + Ta + Ra + 1.5 Pa (7) D + L + Ta+Ra + 1.25 Pa + 1.0 (Yr + Yj + Ym) + 1.25 E (8) D+L+Ta+Ra + 1.0 P, + 1.0 (Yr + Yj + Ym) + 1.0 E' In combinations (6), (7) , and (8) the maximum values of P , aT e a Ra , Yj, Yr, and Ym, including an cppropriate dynamic load factor, should be used unless a time-history analysis is performed to justify otherwise. Combinations (5), (7) , and (8) and the corresponding structural acceptance criteria should be satisfied first without the tornado missile load in (5) and without Y r* Yje and Y, in (7) and (8). When considereing these loads, local section strength capacities may be exceeded under these concentrated loads, provided there will be no loss of function of any safety-related sys'.em. Both cases of L having its full value or being completely absent should be checked.
- 3. Allowable Stresses Allowable stresses provided in ACI-531-79, as supplemented by the following modifications / exceptions, shall apply.
(a) When wind or seismic loads (OBE) are considered in the loading I combinations, no increase in the allowable stresses is permitted. (b) Use of allowable stresses corresponding to special inspection category shall be substantiated by demonstration of compliance with the inspection requirements of the SEB criteria. (c) When tension perpendicular to bed joints is used in qualifying the unreinforced masonry walls, the allowable value will be justified by test program or other means pertinent to the plant and loading conditions. For reinforced masonry walls, all the tensile stresses will be resisted by reinforcement. (d) For load conditions which represent extreme environmental, abnormal, abnormal / severe environmental, and abnormal / extreme environmental conditions, the allowable working stress may be multiplied by the factors shown in the following table: l \ A-2
. . . . ~ .
d TER-C5506-163 i Type of Stress Factor Axial or Flexural Compression 2.5 Bearing 2.5 Reinforcement stress except shear 2.0 but not to exceed 0.9 fy Shear reinforcement and/or bolts 1.5 Masonry tension parallel to bed joint 1.5 Shear carried by masonry 1.3 Masonry tension perpendicular to bed joint for reinforced masonry 0 l for unreinforced masonry 2 1,3 Notes (1) When anchor bolts are used, design should prevent facial spalling of masonry unit. (2) See 3(c).
- 4. Design and Analysis Considerations (a) The analysis should follow established principles of engineering mechanics and take into account sound engineering practices.
(b) Assumptions and modeling techniques used shall give proper considerations to boundary conditions, cracking of sections, if any, and the dynamic behavior of masonry walls. (c) Damping values to be used for dynamic analysis shall be those for reinforced concrece given in Regulatory Guide 1.61. (d) In general, for operating plants, the seismic analysis and Category I structural requirements of FSAR shall apply. For other plants, corresponding SRP requirements shall apply. The seismic analysis shall account for the variations and uncertainties in mass, materials, and other pertinent parameters used. (e) The analysis should consider both in-plane and out-of-plane loads. (f) Interstory drift effects should be considered. i i A-3
TER-C5506-163 (g) In new construction, grout in concrete masonry walls, whenever used, shall be compacted by vibration. (h) For masonry shear walls, the minimum reinforcement requirements of ACI-531 shall apply. (i) Special constructions (e.g., multiwythe, composite) or other items not covered by the code shall be reviewed on a case-by-case basis for their acceptance. (j) Licensees or applicants shall submit QA/QC information, if available, for staff's review. In the event QA/QC information is not available, a field survey and a test program reviewed and approved by the staff shall be implemented to ascertain the conformance of masonry construction to design drawings and specifications (e.g. , rebar and grouting) . (k) For masonry walls requiring protection from spalling and scabbing due to accident pipe reaction (Y r), jet impingement (Y 3), and missile impact (Ym), the requirements similar to those of SRP 3.5.3 shall apply. However, actual review will be conducted on a case-by-case basis.
- 5. References (a) Uniform Building Code - 1979 Edition.
(b) Building Code Requirements for Concrete Masonry Structures ACI-531-79 and Commentary ACI-531R-79. (c) Tentative Provisions for the Development of Seismic Regulations for Buildings - Applied Technology Council ATC 3-06. , (d) Specification for the Design and Construction of Load-Bearing Concrete Masonry - NCMA August, 1979. (e) Trojan Nuclear Plant Concrete Masonry Design Criteria SaSety . Evaluation Report Supplement - November, 1980. l l l l A-4
1- ll APPENDIX B N
SUMMARY
OF WALLS REQUIRING MODIFICATIONS 1 l FRANKLIN RESEARCH CENTER DIVISION OF ARVIN/ CAL 5 PAN 20thand Race Streets Philadelphia, PA 19103
Docket No. 50-346 License No. NPF-3 Serial No. 1-217 September 29. 1981 j Page 1 of 5 TABLE 1 - SUtetARY OF NON-ACmFTABLE WALT 3 ANALYZED UNDER NRC BULIETIN NO. 80-11 Load Causing Wall Area or Item Summary of Corrective Wall /Subuell Non-Acceptance causina Non-Acceptance Action *
- l 311D Det Upper half of east edge is concrete pilaster will be not connected to any support. added to provide support.
1068 SSE Bottom connection of well Systems adjacent to this vall to floor. will not be affected due to postulated well failure. I 2047 SSE Botton connection of well Rangers 31-NCC-5-N5, i no to floor 31-NCC-5-N6 and 31-NCC-5-N7 8 will be modified to remove attachment to well. 2297 SSE Top connection of well Floor bene will be braced. (floor beam) 2337 SSE Bottom connection of wall Angles and expension bolts
- to floor will be used to reinforce i connection.
! 3016(1) OBE Top connection to floor Fixing well 3026 will also above fix this wall. i 3026(1) OBE Adjacent support walls Top connection to floor above (3016 & 3036) do not pese is missing and will be added. acceptance criteria Q
- o l 3036(1) DeE Top connection to floor Fixing wall 3026 will also 5 above fix this wall. $
. E j 3167 Compartment pressure Hamonry and top connection Steel bracing external to 4 due to e break in the of well (floor beam) well will be added. os main feedwater line I
i
Foge 2 of 5 . TAtt2 1 (Cont.) , Load Cemeing Well Area or Itan Summary of Corrective Well/Subwall Non-Acceptance Causina Non-Acceptance Action 3177 Compartment pressure Masonry Steel bracing external to due to a break in the
- well will be added.
main feedwater line 3187 Compartment pressure Masonry and top Steel bracing insternal to due to a break in the meta connection of wall well will be added. feedvater line (floor besa)
- 3237 Compartment pressure due Top connection of Floor bene will be braced to a crack in the main well (floor beoe) and edge connection will be feedwater line and north edge reinforced with angles and i connection to expenaton *bolte.
adjecent concreta wall , Y 3287 Compartment pressure South edge coAnection Connection will.be reinforced N due to a crack in the to adjacent concrete well with angles and expenaten main feedwater line bolto. 3307 Das Top connection of well Floor beam will be braced. (floor beam) . l 3407 ssE Top connection of well Floor been will be braced. (floor bese)
~
i i 3447(2) oss or compartment Masonry Bracing external to well
- pressure esseed by a will be added.
1 crack in the main , I feedwater line 3457(2) est or compartment Masonry Bracing external to well
. pressure caused by will be added. N
] a crack in the main y j feedwater line Q
. m 3467(2) est or compartment Mason ry, Bracing external to wall E pressure caused by a will be added. $
i crack in the main O $ feedwater line .
-\
4 4
Fase 3 of 5 TAtt.E 1 (Cont.) , Load Cassing Wall Area or Item Summary of Corrective i Wall /Subuell k n-Acceptance Cousina Non-Acceptance Action 4016 Ong h oonry, top connection Steel p'11 asters will to floor above and . be added. botton conneetton to floor 4036 Oct hoonry, top connection Str.1 bracing outernal to to floor above, botton well will be added. connection to floor, and east edge connection to adjacent mesonry wall
- l 4107 Compartment pressure hoonry and all connectione Steel bracing " external to y
due to a crack in the to adjacent supports well will be added. tas sImin feedwater line , 4117 Compartment pressure hoonry and att connections Wall will be removed. due to a crack in the to adjacent supporte main feedwater line
- i 4127 Compartment pressure booney and all connections Wall will be removed. ,
, due to a crack in the to adjacent supports i
main feedwater line l 4647 OgE Setemic joint at south end Required solemic joint of wall le missing will be added. 4786(3) OSE hoonry, top connection Steel bracing external to i ta floor above and botton well will be added. connection to floor ' ' 4 Y 4796(4) DeE Top connection to floor Steel bracing external to Q above well will be added. g i < m } 4806 OBE Setemic joint to missing Wall will be removed. 0 l . O 4 i i j l
- - - - - . - --. . . - - ~ - - . _.-- - _ . _ . --
l 1 - TABLE 1 (Cont.) Fase 4 of 5 1 l Load Cemeing Wall Area or Ites Summary of Corrective .i Non-Acceptance causina Non-Acceptance Action . I Watt /Subusti Det Adjacent oopport walle Wall will be removed. I 4317 (4006 & 4826) do not pese . - l' acceptance criteria and
- essonry does not pese seceptance criteria i
s Seismic joint le missing Us11 will be removed. 4826 OGE OgE Masonry usil will be removed 4837 e Masonry Wall u111 he removed. ! 4847 05 l - ( i a Adjacent support well (4447) Wall will be removed. OBE j 1 4857 does not peso ecceptance criterte Ogg Top donnection to floor Steel bracing external l 4886(4) ebove, bottom connection to well will be added. j to floor and side connectica i to adjacent concrete well Ogg Top connection to floor Steel bracing outernal i 4896(4) above to well will be added.
'Tay connection to' floor Steel bracing outernal OgE
> 4906(3) above , to well will be edded. I
- DeE Top connection of well Floor base will be Q l 5107 braced. gi i
(floor bese) , n OgE Masonry Sretens attached to wall $ 5167 have been examined for gl potential failure and a failure is acceptable. l ((
- Top connection of Floor bene will be braced.
5207 ssE vall (floor beam) i 1
. F g m . .ow - g - - . _ s
A Page 5 of 5 TABLE I (Cont.) , Load Causing Wall Area or Item. Summary of Corrective Non-Acceptance Causing Non-Acceptance Action Wall /Subwall 5257 OBE Haeonry Systems att' ached to wall m have been examined for 0, potential fall'ur's and failure is acceptable. i l Notes (I) Wq11e 3016, 3026 and 3036 have been analysed as one well unit. . ' (2) Walle 3447, 3457 and 3467 are one wall unit. (3) Walle 4786 and 4906 are one wall unit. * (4) Walle 4796, 4886 and 4896 are one wall unit.
?
n , l U k w
i APPENDIX C SKETCHES OF WALL MODIFICATIONS l FRANKLIN RESEARCH CENTER l DIVISION OF ARVIN/ CAL 55=AN 20thand Race Streets Philadelphia, PA 19103
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SECTION REINFORCEMENT OF BOUNDARY FOR WALL 3237 V C-2
j . ATTACHMENT 3 i. SGEB STAFF POSIT 0N ON USE OF ENERGY
. BALANCE TECHNIQUE TO QUALIFY REINFORCED MASONRY WALLS IN NUCLEAR POWER PLANTS i
- j. INTRODUCTION Under seismic loads, strain energy transfer through elastic response 'is very i
small compared to the inelastic response for energy dissipation. Therefore, - inelastic non-linear analysis of reinforced masonry walls is an attractive approach. Some of the licensees have relied on a non-linear analysis approach known as " energy-balance technique" to qualify some of the reinforced masonry walls in their plants. 4 The staff and their consultants have reviewed the basis provided by licensees to justify the use of energy-balance technique to qualify the reinfored masonry walls. The staff met with a group of licesees representing approximately ten utilities on November 3, 1982 and January 20, 1983 to discuss this issue.
- Further, site visits and detailed review of design calculations were conducted j by the staff and their consultants to gain first-hand knowledge of field conditions and the application of energy-balance technique in qualifying in place masonry walls. Based on the information gained through the above activities, the staff has formulated the following position on the accept-ability of the use of energy-balance technique to qualify reinforced masonry walls in operating nuclear power plants. The staff's technical basis for the position is discussed in the attached report.
l POSITION l The use of energy-balance technique or any other non-linear analysis approach is not acceptable to the staff without further confirmation by an adequate test 9 I 1
program. The.refore, the staff position consists of the following three options. Adoption of any one of the option and successful implementation will constitute a resolution of the issue regarding the qualification of reinforced masonry walls by energy balance technique or other non-linear techniques.
- 1. Reanalyse walls qualified by the energy-balance technique by linear elastic working stress approach as recommended in the staff acceptance criteria (SRP Section 3.8.4, Appendix A) and implement modifications to walls as needed.
- 2. Develop rigorous non-linear time-history analysis techniques capable of capturing the mechanism of the walls under cyclic loads. Different stages of behavior should be accurately modeled; elastic uncracked, elastic cracked and inelastic cracked with yielding of the central rebars. Then, a limited number of dynamic tests (realistic design earthquake motion inputs at top and bottom of the wall) should be conducted to demonstate the overall conservatism of the analysis results. In this case, "as built" walls should be constructed to duplicate the construction details of a specific plant.
- 3. For walls qualified by energy-balance technique, conduct a comprehensive test program to establish the basic non-linear behavioral characteristics of masonry walls (i.e. load-deflection hysteretic behavior, ductility ratios, energy absorption and post yield envelopes) for material properties and construction details pertaining to masonry walls in question. The f
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4 behavior revealed from tests should then be compared with that of elastic-perfectly plastic materials for which the energy balance technique was originally developed. If there are significant differences, then the energy balance technique should be modified to reflect the actual wall behavior. .l 6 4 d 6 A s e ..- , - . . - - - - - - , , ,- -~- - ---
EVALUATION OF THE APPLICABILITY OF NONLINEAR ANALYSIS TECHNIQUES TO REINFORCED MASONRY WALLS IN NUCLEAR POWER PLANTS i
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Prepared by Harry G. Harris (1) Ahmad A. Hamid (1) Vu Con (2) s
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August 1984 (1) Department of Civil Engineering, Drexel University, Philadelphia, Pennsylvania (2) Nuclear Engineering Department, Franklin Research Center, Philadelphia, Pennsylvania a r , ,4 M s ee o n ~ { '&[PG , je ' 3 6 -F f'
!. INTRODUCTION In response to IE Bulletin 80-11, a total of 10 nuclear power plants have indicated that the energy balance technique has been employed to qualify some reinf orced masonry walls in out-of-plane bending. Based on the review of submittals provided by the licensees and all available literature, the Franklin Research j Center - (FRC) staff and FRC consultants have concluded that the 1 available data in the literature is not sufficient to warrant the use of nonlinear analysis techniques to predict the response of
; masonry walls under cyclic, full.y reversed dynamic loading. As a
- result, a meeting with representatives of the affected plants was '
q held at the NRC on November 3, 1982 so that the NRC, FRC staff 1 i and FRC consultants could explain their concern regarding the applicability of the energy balance technique to masonry walls in i nuclear power plants C13. In a subsequent meeting on January 20, i j 1983, consultants of utility companies presented their rebuttals [2] and requested that they should be treated on a plant-by plant i basis. In accordance with their requests, the NRC staff started , the process of evaluating each plant on an individual basis. In this process, the PetC, FRC staff and consultants visited a few nuclear power plants to examine the field conditions of I reinforced masonry walls in the plants and to gain first-hand 4 knowledge of how the energy balance technique is applied to actual walls. Key calculations were reviewed with regard to the energy balance technique. 1 1 l
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l l EVALUATION OF ENERGY BALANCE ' TECHNIQUE Based on a review of the submittals provided by the licensees, specific plant visits, evaluation of typical design computations and review of all available 1.i terature, it is concluded that the concerns raised by the Franklin Research Center (FRC) staff and consultants pertaining to the use of energy balance technique have not been resolved. A summary of these concerns are listed below:
- 1. Only a few isolated tests have been reported on the lateral resistance of reinforced concrete block and brick masonry walls in out-of-plane bending. These tests can be summarized as follows:
(i) Tests have been conducted on 20' high reinforced concrete block walls 8" thick in running bond and stack bond configurations by Dickey and Mackintosh [33.. These tests, although limited, revealed that, under monotonically increasing load, some of the panels failed in a brittle made prior to reaching yield and that the stack bond was less effective than the running bond. (ii) More recent tests conducted by the ACI-SEASC Task Committee on Slender Walls [4] on face loaded 24' high reinforced masonry walls under monotonically increasing load showed relatively low ductility ratios in the 3 panels that attained failure. Two 6" nominal fully grouted concrete masonry walls attained ductility ratios of approximately 2 when they failed inadvertently in compression. One 6" hollow brick wall tested to f ailure also attained a ductility ratio of approximately 2. It has been noted that walls tested were fully grouted and have high steel percentages (0.22% to 0.37%). (iii) Tests conducted by Scrivener [5,63 on face loaded reinforced masonry walls made of 4 1/4" reinforcing brick revealed high ductilities. The one cyclical 11y loaded panel whose load-deflection results are reported [5] revealed very peculiar hysteretic behavior ur.like the , required elasto-plastic behavior needed for application i of the energy balance technique. l (iv) Tests on small masonry structures resulting from an 1 assembly of various components to form single story l masonry homes have been carried out at the UC, Berkeley j 2 l l
earthquake simulator '[73-E93. The main objective was to provide design recommendations on the minimum reinforcement required for masonry housing in seismic . zone 2. These are the only tests of reinforced masonry walls under realisite earthquake loads. The reinforced j walls tested under out-of-plane bending in this program did not yield under the applied loads. In addition, these walls did not have the boundary conditions of typical applications of masonry walls in nuclear power plants. (v) Dynamic tests on slender reinforced block masonry walls have been conducted at the EERC, University of California, Berkeley f or Bechtel Power Corporation. The program has been conducted to demonstrate the conservatism of the nonlinear dynamic analysis performed , by Computech Engineering Services for the masonry walls i in the San Onofre Nuclear Generating Statioh, Unit 1 (SONGS-1). The FRC staff and consultants witnessed one of , the tests. It was shown that the wall was capable of resisting significant inelastic deformations when subjected to earthquake input motion. It*has to be menti oned, however, that the few tests performed were plant specific and aimed at verifying the conservatism of the nonlinear dynamic analysis technique developed by Computech Engineering Services. Consequently, the - parameters included in the program were limited to "as j 4 built" condition of the walls in SONGS-1. The program ! objective was not to verify the use of the energy balance l technique.
- The above tests that have been conducted on reinforced masonry I
walls and which are relevant to the evaluation of concrete 4 masonry walls in nuclear power plants do not form a sufficient data base to warrant the use of the energy balance technique.
- 2. A Technical Coordinating Committee for Masonry Research (TCCMAR) has been formed under the auspises of the US-Japan Cooperative Research Program. It is a recognition of the urgent i
need for research in the area of seismic resistance of masonry. I The committee met in Pasadena in February 1984 to assess the current state of knowledge and to outline an experimental program to provide the necessary data. It has been concluded that the 4 current state-of-the-art of masonry has not progressed enough to i 3
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i , warrant inelastic analysis methodology of masonry structures C113. A comprehensive test program was recommended. This significant undertaking is a clear indication of the l'ack of test , 1 data available for masonry. (Note: Dr. Hamid serves as a member of TCCMAR.)
- 3. A large number of variables exist in the construction of concrete block walls used in nuclear power plants. For ex ampl e, the walls can be fully grouted, partially grouted, stack bond, i running bond, single and multiple wythes with dffferent block sizes ranging from 4" to 12" in width. No adequate test data exist in the literature to enable a clear understanding of the effects of these variables on the dynamic fully reversed cyclic behavior of masonry walls.
- 4. Effects of cut-outs and eccentric loads due to attachments on reinforced ' concrete masonry walls of the type used in nuclear .
power plants have not been evaluated experimentally. This type of information, when available, will help to substantiate the various assumptions made in the analysis of such safety related
' walls. . .
- 5. ,The limited tests that have been conducted and summarized in item 1 above have pointed out to the inability to preclude brittle type failures with low ductility ratios on face loaded panels under monotonically in, creasing load. A lack of knowledge i
exists on the maximum attainable compressive strains in the face shell of reinforced concrete masonry walls under out-of-plane bending. This is particularly true under cyclic dynamic loading. 4
- 6. In examining the available test data, it is also obvious that there is a significant lack of inf ormation about the post--yield envelope and established cyclic load characteristics for reinforced concrete masonry walls under out-of plane bending which is essential to demonstrate the stable ductile behavior -
required for the applicability of the energy balance technique. This is attributed to the fact that most tests were not conducted to ultimate failure which is essential for the determination of the post yield envelope. This deficiency exists for all of the types of masonry construction used in nuclear power plants [103.
- 7. Some walls are qualified based on one-way bending in the horizontal direction or two-way plate action. These walls are horizontally rein' forced with joint reinforcement embedded in the mortar joints every course or every other course. This type of steel is a high tensile steel with a yield stress as high as 100,000 psi indicating a very limited ductility. Masonry codes are not specific about the usefullness of joint reinforcement, particularly in seismic areas [12,133. If joint reinforcement is ,
to be used to resist tensile stresses, the WSD method should be employed with an allowable steel stress limited to 30,000 psi. The only code C143 that addresses the use of joint reinforcement' in seismic areas for categoriees C and D structures was developed by the Applied Technology Council. This code does not allow the use of joint reinforcement as a load carrying element for these two categories.. Safety-related masonry walls in nuclear power plants would fit into these categories. Information about the 5
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- cyclic- behavior of joint " reinforced masonry walls is not available in the masonry literature at the present time [12,133.
- 8. The energy balance technique has been originally developed as
! an approximate design tool to check the resistance of ductile concrete and steel frame buildings subjected to seismic loads. With the fast development in computers in recent years, more rigorous nonlinear dynamic analyses of ductile structures have also been made possible. NONLINEAR ANALYSIS OF MASONRY WALLS Under seismic loads, strain energy transfer through elastic reponse is very small compared to the inelastic response for energy dissipation. With regard to inelastic behavior, two
. methods have been used to investigate the dynamic response of
! concrete and steel structures to a strong motion earthquake. One of the methods requires the formulation of an inelastic model of the structure utilizing the finite element technique. The model is then subjected to time-history ground motion and the dynamic response is determined. TSN results of this approach, which is time consuming and Ci t2., depends on how accurately the l l structur's is represenwed by che inelasctic model and how well the ,
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material properties are defined. Therefore, a : limited'
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confirmatory dynamic test program should be conducted to check i the conservatism of the assumptions used. l 1 j The other method, which is easier to apply in a design l office, separates the properties of the structure from those of the earthquake. The earthquake is represented by a response t 6 l
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spectrum which is then modif'ied to accomodate the inelastic or ductile response of the wall C153. This method which relies on the energy balance technique requires information about ductility and energy absorbtion capability of masonry wall's which, as discussed previously, have not been demonstrated experimentally for general applications. A ductility factor of 1 or 1.5 is - suggested [163 for damage-level earthquake intensities where as ductilities of 2 to 3 is recommended [163 for use with collapse-level response spectra. Because the energy balance technique is an approximate simplified method, an adequate and more comprehensive data base should be generated to check this design methodology. TEST PROGRAM RELATED TO ENERGY BALANCE TECHNIQUE If a confirmatory test program is elected to justify the use of the energy balance technique, it is expected that the test panels should represent the actual configuration, construction l l details and boundary conditions of masonry walls in nuclear power plants. The test program should cover the different parameters that would affect wall performance such as steel percentage, bond type, partial grouting and block size. The test objectives should be centered upon the following:
- 1. To demonstrate that the masonry walls would maintain their structural and functional integrity when subjected to SSE and other applied loads.
- 2. To demonstrate that a stable ductile behavior characterized by steel yielding is guaranteed and that .any 7
F s brittle failure (e.g. crushing) is precluded. , 3. To develop necessary inf ormation , to veri.fy the energy l balance technique as a methodology for the qualification of reinf orced masonry walls in nuclear power plar.ts.
- 4. To demonstrate that adequate margins of safety exist for walls subjected to design lateral loads.
SUMMARY
, CONCLUSIONS AND RECOMMENDATIONS A review and evaluation of the available inf ormation on the nonlinear behavior of block masonry walls under out-of-plane loading has been presented. It is concluded that test data are l needed to substantiate the use of nonlinear analysis techniques to qualify reinforced block walls in nuclear power plants. To qualify masonry walls based on nonlinear analysis, two 1
, alternatives are recommended: !
l 1- Develop rigorous nonlinear time-history analysis I l techniques capable of capturing the mechanism of the walls under cyclic loads. Different stages of behavior should be accurately modeled: elastic uncracked, elastic cracked and inelastic cracked with yielding of the central rebars. Then, a limited number of dynamic tests (realistic design earthquake motion inputs at top and bottom of the wall) should be conducted to demonstrate the overall conservatism l j of the analysis results. In this case, "as built" walls should be constructed to duplicate the construction details of a specific plant. 2- Conduct a comprehensive test program to establish the B , 1
v .
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basic nonlinear behavioral characteristics of masonry walls (ie. load-deflection hysteretic behavior, ductility ratios, energy absorbtion and post-yield envelopes) for material l properties and construction details pertaining to masonry walls in question. The behavior revealed from the tests should then be compared with that of elastic-perfectly-plastic materials for which the energy balance. technique was originally developed. If there are'significant differences, then the energy balance technique should be' modified to reflect the actual wall behavior.
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. REFERENCES
- 1. Hamid, A.A. and Harris, H.G., " Applicability of Energy Balance Technique to Reinforced Masonry Walls," Franklin Research Center, Philadelphia, PA, June 1982.
- 2. " Rebuttal to Applicability of Energy Balance Technique to Reinforced Masonry Walls," URS/ John A. Blume Associates and Bechtel Power Corporation, January 1983.
) 3. Dickey, W.L. and Mackintosh, A., "Results of Variation of "b"
- or Effective Width in Flexeral Concrete Block Panels," Masonry l Institute of America, LA, 1971.
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- 4. Annonymous, " Test Report on Slender Walls," Repor,t of the Task Committee on Slender Walls, Edited by J.W. Athey, ACI, Southern California Chapter, and the Structural Engineers Association of Southern California, Feb. 1980-Sept. 1982, Los Angeles, CA.
- 5. Scrivener, J., " Reinforced Masonry - Seismic Behavior and Design," Bullglin gi Ngg. Iggland Eggigiy igt Earthgggkg Enginggring, Vol. 5, No. 5, Dec. 1972.
- 6. Scrivener, J., " Face Load Tests on Reinforced Hollow Brick Non-Load-Bearing Walls," New Zagland Engingsting deutnal, July 1969.
- 7. Clough, R., Mayes, R. and Gulkan, P., " Shaking Table Study of Single Story Masonry Houses, Volume 3: Summary, Conclusions and Recommendations," Earthquake Engineering Research Center, Report No. UCB/EERC-79/23, College of Engineering, University of California, Berkeley, CA,. September 1979.
- 8. Gulkan, P., Mayes, R. and Clough, R. " Shaking Table Study of i . Single Story Masonry Houses, Vol. 2: Test Structures 3 and 4,"
Earthquake Engineering Research Center, Report No. UCB/EERC-79/24, College' of Engineering, University of California, , Berkeley, CA, September, 1979.
.9'. Manos, G., Clough, R. and Mayes, R., " Shaking Table Study of Single Story Masonry Houses- Dynamic Performance under Three Component Seismic Input and Recommendations," Report No. UCEERC-83/11, Univ. of Calif., Berkeley, July 1983.
- 10. Hamid, A.A., Harris, H.G., Con, V.N. and Chokshi, N.C.,
" Performance of Block Masonry Walls in Nuclear Power Plants,"
EC9ERRdiDGE Qi thf IbiCd GADAdlAQ UAE90Cy EYEEE11Mg, Alberta, Canada, June 1983, pp. 12-1 to 12-9.
- 11. Hamid, A.A. and Harris, H.G., " State-of-the-Art Report:
Nonlinear Behavior of Reinforced Masonry Walls under Out-of-Plane Lateral Loading," Proceedings of the International Symposium on Reinforced and Prestressed Masonry, Edinburgh, Scotland, August 1984. , 10
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- 12. Hamid, A. A., Harris, H. G., and Becica, I. J., "The Use of Joint Reinforement In Block Masonry Walls," Franklin Research l
Center, Philadelphia, March 1983.
- 13. Harris, H.G., Hamid, A.A., Becica, I.J., Con, V.N., and Chokshi, N.C., "The Use of Joint Reinforcement in Qualifying Masonry Walls in Nuclear Power Plants," Presented at the ASCE Specialty Conference on Structural Engineering in Nuclear Facilities, Sept. 10-12, 1984, NC State University, Raleigh, North Carolina. -
- 14. Applied Technology Council, " Tentative Provisions for a Development of Seismic Regulations for Buildings," ATC 3-06, (NSF Publication 78-8, NBS Special Publication 510), U.S. Government Printing Office, June 1978.
- 15. Englekirk, R.E., Hart, S.C. and the CMA of California and Nevada, Entthgggkg pggign gi Ggagtgtg Uggggty Buildin9Es MQlz 1 Branenza Entstta analxmis and Emental Eattbevaka Medalion GQufidRCat19ni, Prentice-Hall, Inc., Englewood Cliffs, N.J.,
1982.
- 16. Englekirk, R.E., Hart, G.C. and the CMA of California and Nevada, Estthggght Eggign gi Ggngtgtg daggety Egildings. Melz 2 EtCRnEth DR11Gn 91 Qum-in-Eeut-EteCr Buildinen, Prentice-Hall, Inc., Englewood Cliffs, N.J., 1984.
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