ML20040B725

Survey Procedure for Concrete Masonry Walls in Category I Bldgs. Design Criteria for Concrete Masonry Walls in Category I Structures & Commentary on Criteria for re-evaluation of Concrete Masonry Walls Encl

ML20040B725
Person / Time
Site:	Grand Gulf
Issue date:	01/19/1982
From:	MISSISSIPPI POWER & LIGHT CO.
To:
Shared Package
ML20040B716	List: ML20040B715 ML20040B725 ML20040B732 ML20040B741 ML20040B743
References
PROC-820119, NUDOCS 8201260357
Download: ML20040B725 (32)

Text

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APPENDIX A  !

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SURVEY PROCEDURE FOR CONCRETE MASONRY WALLS IN CATEGORY I BUILDING 5 ,

GRAND GULF NUCLEAR STATION L

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I Table of Contents 1.0 PURPOSE

' 2.0 SCOPE 3.0 PRE-WALKDOWN PREPARATIONS 4.0 WALKDOWN PERSONNEL 1

5.0 WALKDOWN PROCEDURE ATTACliMENTS

1. Walkdown Checklist

2. Sample - Wall Elevation Sketch

3. Sample - Table for Equipment and System Supports Identification j

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i 1.0 PURPOSE .

This procedure specifies the work to be perfor=ed and the data to be

, accumulated to provide sufficient information for the evaluation of

{ concrete masonry walls in Category I Buildings.

2.0 SCOPE 2.1 The surveys shall be conducted and data accumulated for all concrete masonry walls which are in proximity to or have attach-

,,. ments of safety related systems such that failure of the wall could affect the safety related system.

Surveys shall apply to masonry walls in the Auxiliary Building and the Control Building. Masonry walls with steel cover plates on the faces of the wall shall be excluded from these surveys.

2.2 Sufficient data is to be recorded to determine the characteristics of the wall construction, geometry, location and magnitudes of applied loads and corresponding connection details for safety and non-safety systems supported by the wall.

2.3 The walkdown information will be forwarded to GPD Engineering and elevations of the walls will'be prepared on the Architectural drawings.

3.0 PRE-WALKDOWN PREPARATIONS The fo,llowing items will be prepared by Engineering:

3.1 "WM" Drawings (Wall Mark Drawings)

Reproducible copies of the latest revisions of the Architectural drawings will be used to assign identification marks for the walls to be surveyed. A unique identification mark for the face of a wall will be assigned as follows:

t C - 133 - 001 N Building Identification Floor Elevation Wal'1 Number-Identification of Wall Face (

LEGEND: (1) C - Control Bldg. (2) N - North face of Wall (2) A - Auxiliary Bldg. S - South face of Wall E - East face of Wall W - West face of Wall 9

3.2 Wall Elevation Sketch,

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Existing Architectural wall drawings will be utilized. An

/ elevation sketch with the wall mark identification will be provided for each face of the wall. Survey information will be plotted on  ;

the elevation sketch. Supplementary sketches will be developed as  ;

ne cessa ry.

3.3 Standard Connection -and Attachment Det. ails These details will be referenced on the survey sketches where applicabic. '

3.4 Walkdown Inspection Checklist 9

The checklist will be used as an aid to the survey team to acquire .

walkdown information and for the checker to review the completed I survey information. .

3.5 Table for Equipment and System Supports Identification The table will be used to provide all the infor=ation needed for items referenced on the survey elevation sketches.

l 4.0 WALKDOWN PERSONNEL '

The survey teams will be under the direction of an engineer from the project Civil discipline who will be at the jobsite for the duration of the survey. The Piping, Electrical and Instrumentation Resident Engineers and ERT personnel may provide the survey team with assistance in identifying safety related items or systems and in estimating weights of items attached to the walls.

5.0 WALKDOWN PROCEDURE The walkdown team shall survey the walls shown on the wall elevation sketches and shall record the following information:

5.1 Structural configuration of the wall i

l Overall wall dimensions: Height, length and thickness  !

Wall boundary connection details: Top , bottom and sides Type of wall: Load-bearing, partition, single or multiple wythe ,

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1 5.2 Safety-related Items Attached to the Wall a) Locate preferably at the item center lines by two dimensions and plot the size of the item.

b)

Identify the attached equipment or system. Record pipe hanger, cable tray support, HVAC duct support, or conduit I support numbers and any other markings or information which may be useful in the identification of the items.

I c) Determine or estimate weights of equipment and components

. where practical. Record sufficient date for supports of

! systems so that tributary gravity loads and seismic loads can be estimated. This will consist of locating the next i supports, not on the wall under consideration, and providing data such as size / number of conduits, instrumentation lines, cable trays, pipes, HVAC ducts, etc. supported by the wall.

] d) Determine and record the way items are attached to the wall l (e.g. , through bolts with backing plates, concrete expansion i

anchors, etc.). Record the size of through bolts, expansion j anchors, etc. , and the relationship between anchors and mortar

) joints. g i .

j e) For systems passing through penetrations, record the

penetration closure detail or presence of grouting (i.e.,

l evidence of support or restraint provided by the wall to the

! system). If the system is supported at the penetration, or if the closure detail specified in the penetration schedule will provide support, identify the system and provide the location l of the next support on each side of the wall for load evaluation.

f) If an item cannot be positively identified as safety related or non-safety related, then all the provisions of Section 5.2 shall apply.

5.3 Non-safety Related Items Attached .o the Wall a) Locate preferably at the centerlines by two dimensions and plot size of the item for the following:

1) Supports for items greater than one inch in diameter or groups of items contributing to support loads greater than 25 lbs.

ii) Significant attachments estimated to weigh more than 25 lbs.

! b) Record weights for all supports or attachments greater than 25 lbs. (See also 5.2 c.)

c) Items estimated to weigh less than 25 lbs. sh,all be plotted with approximate dimensions. An estimate of the weight shall be recorded.

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d) Determine and record the manner in which items are attached to the wall (as described in Section 5.2 d.).

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e) For systems passing through penetrations, record the

, penetration closure details (as described in Section 5.2 e.).

5.4 Penetrations Verify the existence of the penetrations as shown on the wall elevation sketches. Additional penetrations will be located by dimensions and the penetrating system will be identified.

5.5 Potential Structural Problems Show the location and size of structurally significant cracking (by visual inspection) as determined by the survey team. Survey the general condition. of the masonry wall and attachments to the masonry wall.

5.6 Existing Wall Reinforcements / Support Systems Structural beams or columns which provide additional reinforcement / support to the wall or openings will be verified and/or recorded. In addition, lintel details using reinforced concrete, structural steel channels, etc. shall be identified for all openings. Any attachments to wall reinforcements / supports shall be recorded with sufficient data so that gravity and seismic 1.oads can be estimated.

5.7 5fawallsupportssafetyrelateditems,thenidentificationof safety-related items in proximity to the wall is not required. If a wall does not support any safety-related items, then a survey shall be done to identify any safety-related items in proximity to the wall. An item in proximity to a masonry wall is defined as located within an arc (with focus at the base of the wall and length equal to the wall height) extending from the top of the wall to the floor, but not beyond compartments.

5.8 Equipment, systems or components located within 1 inch of the face of a CMU wall and not supported by'the wall shall be identified by support or equipment number. The location, size and estimated weight of the item shall be recorded on supplemental sheets. If a support or equipment number is not available, any information which may be used to identify the item'shall be recorded.

5.9 Existing Wall Support Details Reference shall be made, where applicable, to the standard connection details of all wall supports. Non-standard details will be shown on the survey sketch. The gap between the face of the wall and the support steel shall be noted where it exceeds 1/8 inches. Where fireproofing prohibits verification of the top connection detail, field engineering will aid in removing enough fireproofing so that the detail may be identified if required.

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1 5.10 For specific walls defined by engineering as not needing to be designed to Category I requirements, a survey will be made to verify that there are no safety related items attached to, or in proximity to the walls.

5.11 Dimensions shall be recorded to the nearest one inch. Where limited accccs prevents physical measurement, dimensions shall be estimated to the nearest six inches, and noted that they are estimates.

5.12 Photographs The team leader will specify areas to be photographed, to clarify or to supplement the survey sketches. Photographs will be labeled with the wall identification number.

5.13 Sign Off Procedures The wall elevation sketch shall be co=pleted with the survey infor:ation specified in Section 5.0 for each face of the wall.

The elevation sketch and supplementary sketches shall be signed and dated by the originator, i i

• A visual inspection shall then be made to verify all the information shown on these sketches. Af ter this verification is completed, the sketches shall be signed and dated by the respective team leader. The walk-down inspection checklist may be used as an ,

aid to check that all information required by the walkdown is r'ecorded.

e Tne table for equipment and systems support identification will be completed and signed by the originator and team leader.

5.14 Training Each team member vill be instructed to properly apply the " Survey Procedure for Concrete Masonry Walls." Prior to walkdown, the team leader will discuss the contents of the procedure and shall provide additional instructions if decessary on methods to be followed during the survey.

5.15 For the second and subsequent walkdowns, information shall be transcribed (in red) on to copies of the original survey sketches.

Additional sheets may be used as required. Each revised sketch and all additional sheets shall be signed and dated by an originator and a checker.

Sheet 1 of 2 Attach =ent 1 CONCRETE MASONRY WALL PROGRAM Walkdown Checklist

1. Overall Wall Dimensions

- Height

- Length

- Thickness

2. Boundary Connection Details

- Top ,

- Bottom

- Sides

3. Type of. Wall

- Bearing

- Partition

- Single or multiple wythes

- Other i

4. Supports Attached to the Wall

- Electrical conduits and/or trays

- Instrumentation ,

- Piping (small or large)

- HVAC

- Equipment or components

- Other

. Sheet 2'of 2 Attachment 1

5. Information for the Above

- Location

- Identification

- Weight

- Attachment detail

- Relationship to mortar joint

- Grouted penetrations

6. General

- Significant cracks 1

- Wall reinforcements / Support systems

- Photographs

- Verify penetrations

- Table for equipment and systems supports. Identification to be completed

- Signatures I

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APPENDIX B i

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APPENDIX B DESIGN CRITERIA FOR CONCRETE MASONRY WALLS IN CATECORY I STRUCTURES

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DESIGN CRITERIA FOR CONCRETE MASONRY WALLS IN CATECOPY I STRUCTURES 1.0 CENERAL l.1 Purpose This criteria is provided to establish design requirements for use in evaluating the structural adequacy of concrete block walls. '

1.2 Scope Concrete masonry walls in Category I structures shall be inspected to determine whether safety related equipment and/or systems are attached to or located in the vicinity of the walls. Walls identified as such shall be designed to perform their intended function under the loads and load combinations prescribed herein. Verification of wall adequacy shall include a review of local transfer of load from block into wall, global response of wall, and transfer of wall reactions into supports where response spectra are defined. .

Masonry walls without safety relat d equipment or systems attached to or located in the vicinity of the walls shall be designed as non-Category I.

2.0 COVERNING CODES AND REFERENCE. DOCUMENTS ,

2.1 National Concrete Masonry Association (NCMA) " Specification for the Design and Construction of Load-Bearing Concrete Masonry," August 1970; except that ACI 531-79 " Building Code Requirements for Concrete Masonry Structures," Chapter 10, shall apply for allowable stresses.

Supple 6cntal allowable stresses as specified herein shall be used for l

cases not directly covered in the governing code.

2.2 Specification 9645-A-004.2, " Technical Specification for j Furnishing, Delivery, and Erection of Concrete Masonry Units."

1 2.3 " Block Wall" Program, latest version.

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3.0 LOADS AND LOAD COMBINATIONS i

3.1 Loads 4

The following loads shall be considered in the analysis:

D= Dead Load including the dead weight of the wall; equipment, systems

' or components supported on the wall; and other applicable loads transferred to the wall from slab or roof.

i L= Live Load transferred from slab or roof.

. E= Operating basis earthquake load E'= Safe shutdown earthquake load

• W= Wind load.

W'= Tornado depressurization load on interior walls.

P= Pressure load due to a postulated pipe break (where applicable).

R= Forces related to a postulated pipe break, including jet impingement loads. . -

T= Force on structure due to thermal expansion of pipes during normal operating conditions.

Ta = Thermal load due to a postulated pipe break (where applicable) 3.2 Load Combinations Combination Stress Limit (See Note) 3.2.1 D+L+T S o

3.2.2 D+L+T o

+W S e

3.2.3 D+L+T +E S o

3.2.4 D+L+T + E' S' o

3.2.5 D+L+T + W' -

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3.2.6 D + L + (To+ T )a + R + 1.25P + 1.25E S' 3.2.7 D + L + (To + T a) + R + P + E' S' Note: S = Allowable stress as given !n Sectica 5.1 S'= Allowable stress as given u. Section 3.2

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1 j 4.0 MATERIALS ,

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a Materials are as specifted in Architectural Specification 9645-A-004.2.

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! Material properties required to evaluate block walls are su=marized as follows:

} Masonry compressive strength, f' m -

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Mortar compressive strength, mo ,

Grout compressive strength, f' c t . . ,.

. me. _. 7o, Reinforcing yield strength, f , _

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llollow Lightweight Units, Grade N-1 f' = 1350 psi. p '.4 cs -

m

Cor. forming to ASTM C-90 .

Solid Normal Weight. Grade N-1 f' = 1270 psi.

Conforming to ASTM C-145 t

Mortar, Type PL m - 2500 psi. ,

9 Conforming to ASTM C-476, for walls with vert. -

I reinforcing. '

Mortar, Type M m = 2500 psi. ,

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Conforming to ASTM C-270, for walls without vert.

reinforcing.

1 f' = 2500 psi. - sw -

l Grout j Conforming to ASTM C-476. ghax, Reinforcing Bars, Grade 60 f = 60,000 psi. ..

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Conforming to ASTM A615-75 ~. -3. ';;fM.

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a llorizontal Joint Reinforcing, Dur-0-Wall f = 70,000 psi.

Ladur type with 3/16 inch diameter longitudinal rods and d') gauge cross rods. -

L 5.0 DESIGN ALLOWABLES '

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5.1 Design allowables for load combinations which contain dead, '

J live, operating thermal, operating basis earthquake or wind loads

. (equations 3.2.1 through 3.2.3) shall be as follows:

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5.1.1 Ma son ry .

The allowable tension, compression, shear, bond, and bearing stresses shall be as given in ACI 531-79.

5.1.2 Collar Joints The allowable shear and tension stresses shall be assumed to be zero unless verified by tests.

5.1.3 Cell Grout '

The allowable tension stresses shall be 2.5 e f' 5.1.4 Reinforcing Steel The allowable tension and compression stresses shall be as given in ACI 531-79.

5.1.5 In-Plane Strains In-plane effects due to interstory drif t may be determined by analysis or in plane strains ( A /H) shall by limited to 0.00012 for an unconfined condition, where ( A ) is the relative displacement between the top and bottom of the wall and (H) is the height of the wall. A wall confined 4

on all four sides may be limited to a strain of 0.0008 provided the structural shear resisting elements bounding each vertical side of the wall have a shear resisting capability larger than the wall, and the wall width to height ratio is at least 0.5.

5.2 For load combinations which contain dead, live, accident pressure, accident thermal, tornado or safe shutdown (design basis) earthquake loads (equations 3.2.4 through 3.2.7), the allowable stress (S) shall be multiplied by the factors given below to obtain the factored design allowable (S').

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 f Shear reinforcement and/or bolts 1.5 7 Masonry tension parallel to bed joint 1.5 Shear carried by masonry 1.3 Masonry tension perpendicular to bed joint for reinforced masonry 0 for unreinforced masonry 1.3

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5.2.1 Reinforcing Bar Lap Splices Reinforcing bar lap slices shall be 30 bar diameters as given in the Architectural Specification 9645-A-004.2. Reinforcing embedment length (anchorage) shall be provided to develop the design stress level.

Allowable bond stresses may be increased by a factor of 1,67 in

, determining splice and anchorage lengths.

5.2.2 Impact and Suddenly Applied (Step Pulse) Loads Load combinations which contain loads due to missile impact, jet impingement or pipe whip may exceed the allowables provided there will be no loss of function of any safety related system. The chief civil engineer will be consulted regarding analytical techniques to be applied.

5.2.3 In-Plane Strains In lieu of a more rigorous analysis, in-plane strains due to interstory drif t may be limited to 1.67 times the values in Paragraph 5.1.5.

5.3 Da= ping f

5.3.1 The damping values to be used shall be as follows:

a) For uncracked sections use 2 percent for both OBE and SSE.

b)

• For cracked sections use 2 percent for OBE and 5 percent for SSE.

5.4 Modulus of Rupture 5.4.1 The extreme tensile fiber stress for use in determining the lower bound uncracked moment capacity is 6 f' .

4 5.5 Non-Category I Masonry Walls 5.5.1 Concrete masonry walls not supporting safety systems but whose collapse could result in the loss of required funccien of safety related equipment or systems shall be evaluated the same as walls that support safety systems.

5.6 Inspection

• The allowable stresses from Section 5.0, br,aed on inspection of construction, shall be used unless otherwise directed by the civil group supe rvisor.

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! 6.0 ANALYSIS AND DESIGN 6.1 Structural Response of Masonry Walls i

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6.1.1 Equivalent Moment of Inertia (I ) -

To determine the out-of-plane frequencies of masonry walls, the uncracked behavior and capacities of the walls (Step 1) and, if applicable, the cracked behavior and capacities of the walls (Step 2) shall be considered.

Step 1 - Uncracked Condition The equivalent moment of inertia of an uncracked wall (I ) shall be obtained from a transformed section consisting of the block, mortar,

, cell grout and core concrete. Alternatively the cell grout and core concrete, neglecting block and mortar on the tension side, may be used. -

Step 2 - Cracked condition if the applied moment (M ) due to all loads in a load combination exceeds the uncracked moment capacity (M . , the wall shall be considered to be cracked. In this . event"#)the equivalent moment of inertia (I ) shall be computed as follows:

IM ) 3 f M I = 1 + 1- cr)~ 3 I e tM -

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cr " r y where, M = Uncracked moment capacity M, = Applied maximum moment on the wall I

g = Moment of inertia of transformed section I = Moment of inertia of the cracked section 4

f = Modulus of rupture (as defined in Paragraph 5.4.1) y = Distance of neutral plane from tension face If the use of I results in an applied moment M which is less than M then the wall sfiall be verified for MCr .

For walls in which two-way spans are considered, the chief civil engineer will be consulted for analytical approaches.

The moduli of clasticity for use in dynamic analyses shall be as follows: .

2,= For masonry units 1000 f',

4 E = 57,000 f' For cell grout

4 6.1.2 Modes of Vibration - -

The effect of modes of vibration higher than the fundamental mode shall be considered. For this purpose, a modal analysis may be performed.

Alternatively, the inertia load on the wall due to its acceleration for the fundamentai mode may be considered as.a uniform load. The corresponding bending moment and reaction will account for the higher

. mode effects. .

6.1.3 Frequency Variations Uncertainties in structural frequencies of the masonry wall due to variations in structural properties and mass shall be taken into account. Significant variables include mass, boundary conditions, modulus of elasticity, extent of cracking, vertical load, in-plane and out-of-plane loads and two-way action. To account for the effect of frequency variations, it is considered conservative to use the lower bound frequency if it is on the higher fre'quency side of the peak response spectrum. If the lower bound f eqtiency is on the lower frequen:y side of the peak, the peak acceleration shall be used unless a more detailed analysis is performed.

6.1.4 Accelerations f For a wall spanning between two floors, the effective accelerations shall be the average of the accelerations as given by the floor response spectra corresponding to the wall's natural frequency.

6.1.5 ', Multi-Wythe CMU Walls The analysis of multi-wythe walls shall be based upon the assumption that each wythe acts independently since the allowable collar joint shear and tension stresses are assumed to be zero. Therefore, the seismic load and section properties of only one wythe shall be used in the analysis of each wythe of multi-wythe CMU walls.

6.2 Structural Strength of Masonry Walls 5

6.2.1 Boundary Conditions Boundary conditions shall be determined considering ene-way or two-way spans with hinged, fixed or free edges as appropriate. Conse rvative l

assumptions may be used to simplify the analysis as long as due consideration is given to frequency variations.

l 6.2.2 Distribution of Concentrated Out-of-Plane Loads ,

Two-Way Action

• Where two-way bending is present in the wall the localized moments per unit width under a concentrated load can be determined using appropriate analytical procedures for plates. Standard solutions and tabular values based on plastic theory contained in textbooks or other. published l documents can be used if applicable for the case under investigation (considering 1 cad location and boundary conditions),

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One-Way Action .

For dominantly one-way bending, local moments can be determined using beam theory and an effective width of six times the wall thickness.

However, such moments shall not be taken as less than that for two-way plate action.

6.2.3. Attachments Attcchment loads shall be obtained from survey sketches and as-built i

design drawings. Attach =ent loads greater than 100 lbs. shall be treated as concentrated loads. Loads less than 100 lbs. may be converted to uniformly distributed loads in lieu of the concentrated loads.

6.2.4 Interstory Drif t Effects Interstory drif t effects shall be derived from the original dynamic analysis.

6.2.5 In-plane and Out-of-plane Effects The combined effects of in-plane (d.g., seismic) and out-of-plane (e.g.,

piping) loads shall be considered. '

6.2.6 Stress Calculations All stress calculations shall be performed by conventional methods prescribed by the Working Stress Design Method or other accepted principles of engineering mechanics.

6.2.7 Analytical Techniques In general, classical design techniques shall be used in the evaluation.

The computer program " Block Wall" (Reference 2.3) may be utilized as much as possible to obtain the seismic responsa of the wall. This program uses a three degree of freedcm beam model.

Simplified analytical assumptiond may be used as justified. However, more refined methods such as finite element analysis may be used on complicated problems on a case by case basis.

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f APPE DIX C i

l COFDfENTARY ON CRITERIA FOR THE RE-EVALUATION OF CONCRETE MASONRY WALLS i .

, CONTENTS J

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1.0 GENERAL s

2.0 GOVERNING CODE 3.0 LOADS AND LOAD COMBINATIONS 4.0 MATERIALS I

5.0 DESIGN ALLOWABLES '

4 6.0 ANALYSIS & DESIGN a

REFERENCES i

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COMMENTARY ON CRITERIA FOR THE RE-EVALUATION OF GONCRETE MASONRY WALLS IERAL L Purpose On May 3, 1980, the NRC issued I&E Bulletin 80-11 entitled, .. , .

" Masonry Wall Design," to certain Owners of operating reactor '

facilities. One of the tasks required by the bulletin was to establish appropriate re-evaluation criteria. A detailed justi- -

fication of the criteria along with quantified safety margins are also to be provided by the Owner. This commentary serves as justi- 4 M, e .p,;s.j.;g g g s; fication of the criteria used and provides a discussion of the margins of safety.

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.2 Scope ,

The concrete masonry walls are evaluated for all applicable loads and load combinations. Calculated wall stresses are compared -

against an allowable stress criteria. Wall stresses are maintained within the elastic range of the load carrying components.

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Anchor bolts, embeds and bearing plates provided for s,upport of '

systems attached to the walls are the subject of another NRC .

bulletin and are not considered to be within the scope of this .

.)

evaluation.

VERNING CODE -

e code referenced in the Grand Gulf Safety Analysis Report (SAR) is s' -M- <

.ed (see Design Criteria, Appendix B). This code does not address the ,

. normal loads typically applied to nuclear power plant design. b^?w ""^.-: , Mi. m x._

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erefore, supplemental allowables and alternative design techniques are ecified in the criteria for cases not directly covered by the code.

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DADS AND LOAD COMBINATIONS l, . ,

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4^.1 Je loads identified and defined in the SAR for safety related  ? s1 D ructures form the basis for licensing of the plant and,are used in the ' ' ' "' fl f-l#I%g .%

e aluation of the masonry walls. The load combinations are consistent e>F' NDe-th those listed in the FSAR for seismic Category I structures other e

ian the Containment Building. The' combinations include loads which are Scountered during normal plant operating conditions and design accident ad extreme environmental conditions; hTERIALS gterialstrengthsaredeterminedfromprojectspecifications, drawings i td field documentation. . . - .

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5.0 DESIGN ALLOWABLES .

5.1 Allowables in this section apply to loads and combinations of loads which are normally encountered'during plant operation or shutdown, and include dead loads, live loads, normal operating thermal effecta, and pipe reactions. In addition, this section covers allowables for loads infrequently encountered, such as operating

' basis earthquake and wind loads. The loads in the various load combinations have no increase factors and stresses are maintained t well within the elastic range.

In general, the governing code allowables are applied. However, for cases not covered by the code, such as grout tension, allowables are based on a factor of safety of 3 against failure.

In-plane strain allowables for interstory drif t effects for non-shear walls were established well below the level of strain re-quired to initiate significant cracking. The allowable strain for a confined wall was based on the equivalent compression strut model discussed in Reference 1 and modified by a factor of safety of 3.0 against crushing. Test data (References 1 through 7) was reviewed to determine cracking strains for confined masonry walls subjected to in-plane displacements andiconfirms the predicted strain as given by the equivalent s t ru t' model.

5.2 This section deals with factored loads and other abnormal loads which are credible but highly improbable such as the safe shut-down earthquake, tornado loads and loads generated by a postulated high energy pipe break accident.

Code allowable stresses for masonry in tension, shear and bond are increased by factors ranging from 1.3 to 1.5. In general, this provides a minimum factor of safety against failure of 2.0 (3 +

• 1.5). Masonry allowable compression stresses are increased by a factor of 2.5 with a safety factor of 1.2 (3 + 2.5).

Allowable stresses for reinforcing steel are increased by a factor of 2.0, but limited to 0.9 times the yield strength, which is typical for reinforcing stedl which is required to resist factored and abnormal loads.

These factors are consistent with the NRC's SEB " Interim Criteria

) for Safety-Related Masonry Wall Evaluation," Revision 1. July 1981 i

(See Appendix D) . -

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ee o s Stresses due to the local effectr. of abnormal dynamic loads, such as missile impact, jet impingement or pipe whip,'may exceed the allowables. However, safety systems attached or adjaceat_to the wall are evaluated to determine if severe cracking, local .spalling-'

or excessive deflection will result in loss of required function -

of the system or equipment. Where gross failure of a masonry wall; \

l must be precluded, the provisions of ACI 349-76, Appendix C, or

' applicable theoretical techniquer. or experimental evidence is usgd '

to evaluate wall acceptability. -

5.3 Damping for unreinforced uncracked walls was conservatively bet at '

2% for OBE and SSE corresponding to stress levels ranging from ^

approximately 0.3 to 0.6 of ultimate. .

Damping for reinforced walls which are expected to erack due to out-of-plane seismic inertia are set at 2% for OBE and 5% for SSE. - -

These values are typically recognized as being conservative for reinforced masonry.

5.4 The modulus of rupture of concrete, grout and mortar was assumed to vary by 20%, therefore, a lower bound modulus of rupture is deter-mined by applying a reduction factor of 0.8 to the theoretical con-crete modulus of rupture of 7.57/ f'c or to the modulus of rapture determined by testing samples taken from the as-built structure. '

I 6.0 ANALYSIS AND DESIGN '

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6.1 The structural response of the masonry walls subjected to. cut-of-plane seismic inertia loads is based on a constant value of gross m6 ment of inertia along the span of the wall for the elastic (uneracked) condition. If the wall is cracked, a better estimate of the moment of inertia is obtained by use of the ACI-318 formula for effective moment of inertia used in calculating immediate deflections. (Reference 15)

The effects of higher modes of vibration and variations in fre-quencies are c'onsidered on a case-by-case basis. The use of the average acceleration of the floors supporting the wall is considered suf ficiently accurate for the purpose of this evaluation.

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' ' masonry walls is highly sensitive to the boundary conditions assumed for the analysis. Fixed end conditions are justified for

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, carrying capability of the wall and support.

Distribution of, concentrated loads are affected by the bearing i

f. area under the load, horizontal and vertical wall stiffness, j' '

' boundary conditions-and proximity of load to wall supports.

[ Analytica) 'dures applied to plates based on elastic theory are used reine the appropriate distribution of concentrated loads.

For predominately one-way action, an effective beam width of six timey the wa41 thickness for distribution of concentrated loads

, is consarygtive for the following conditions:

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a)- Loncentrated load at midspan; simple supports: L > 9.6T l b) Concentrated load at midspan; fixed supports: L > 19.2T l

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• a is the distance between the concentrated loads producing a couple T is the thickness of the wall '

Interstory drif t values are derived from the original dynamic analyris. Strain allowables for in-plane drif t effects on non-shear walls and are set at sufficiently conservative levels, such that a reasonable margin remains for out-of-plane loads. Out-

' of-plane drift effects are considered if some degree of fixity exists at the top. and/or boqtom of the walls.

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REFERENCES

1. Klinger, F. E. and Bertero, V. V., "Infilled Frames in Earthquake Resistant Cor.struction," Report No. EERC 76-32, Earthquake Engineering t Researci. Center, University of California, Berkeley, CA, December,1976. f P. Heli, R. and Salgado, G., "Comportamiento de muros de matposteria sujetos a cargas laterales," (Behavior of Masonry Wall Under Lateral l

~

Loads. Second Report.) Instituto de Ingenieria, UNAM, Informe No. 237,  !

September, 1969. I E

!' 3. Meli, R., Zeevart, W. and Esteva L., "Comportamiento de muros de macposteria hueca ante cargas alternades," (Behavior of Reinforced

[

Masonry Under Alternating Loads), Instituto de Ingenieria, UNAM, Informe No. 156, July, 1968. l q

4. Chen, S. J., Hidalgo P. A., Mayes, R. L., Clough, R. W., McNiven, l' H. D. , " Cyclic Loading Tests of Masonry Single Piers, Volume 2 - Height to Width Ratio of 1 " Report No. EERC 78-28, Earthquake Engineering Research Center, University of California, Berkeley, CA. , November, 1978. i 1 5. Mainstone, R. J., "On the Stiffnesses and Strengths of Infilled Frames,"

Proc. I.C.E., 1961. I

i

6. Hidalgo, P.A., Mayes, R. L., McNiven, H. D., Clough, R. W., " Cyclic t

(

Loading Tests of Masonry Single Piers, Volume 1 - Height to Width Ratio '

of 2." Report No. EERC 78/27, Earthquake Engineering Research Center.

University of California, Berkeley, CA. ,1978. t l 7. Hidalgo, P. A. , Mayes, R. L. , McNiven, H. D. , Clough, R. W. , " Cyclic j Loading Tests of Masonry Single Piers, Volume 3 - Height to Width Ratio l

of 0.5," Report No. EERC 79/12. Earthquake Engineering Research Center, '

University of California, Berkeley, CA. ,1979.

8. Blume, J. A. , N.

M.' Newmark, and L. H. Corning, " Design of Multistory Reinforced Concrete Buildings for Earthquake Motions," Portland Cement Association, 11. 1961. ,

9. Newmark, N. M., " Current Trends in the Seismic Analysis and Design of i High-Rise Structures," Chapter 16. Earthquake Engineering Edited by R.

L. Wiegel, McCaw-Hill, 1970.

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10. Gabrielson, B. L. and K. Kaplan, " Arching in Masonry Walls Subjected to Out-of-Plar.c Forces," Earthquake Resistance of Masonry Construction, National Workshop, NBS 106, 1976. pp. 283-313.

11. McDowell, E. L., K. f. McKee, and E. Savin, " Arching Action Theory of Masonry Walls," Journal of the Structural Division, ASCE Vol. 82, No.

ST2, March, 1956. Paper No. 915.

12. McKee , K. E. and E. Ssvin, " Design of Masonry Walls for Blast Loading "

Journal of the Structural Division, ASCE Transactions, Proceeding Paper 1511, January 1958.

13. Scrivener, J. C. , " Reinforced Masonry-Scismic Behaviour and Design "

Bulletin of New Zealand Society for Earthquake Engineering, Vol. 5, No.

4. December 1972.

14. Scriverner, J. C. , " Face Load Tests on Reinforced Hollow-brick Non-loadbearing Walls," New Zealand Engineering, July 15, 1969,

15. Branson, D. E., " Instantaneous and Tice-Dependent Deflections on Simple and Continuous Reinforced Concrete Beams " HPR Report No. 7. Part 1 Alabama liighway Department. Bureau of Public Roads August 1965, pp.

1-78.

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i APPE.' DIX D Comparison of Grand Gulf CMU 'Jall Design Criteria with Revision 1 of NRC's "SEB Interim Criteria for Safety Related Masonry k'all Evaluation," (July 1981) 4 A

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1. General Reauirements The materials, testing, construction, and inspection for the concrete masonry unit (CMU) walls in the Grand Gulf Nuclear Station, Units 1 & 2 are controlled by Specification 9645-A-004.2 (Appendix E).

The design of CMU walls is governed by the National Concrete Masonry Association (NCMA) " Specification for the Design and Construc' tion of Load-Bearing Concrete Masonry," August 1970. Design allowable stresses are specified in the American Concrete Institute " Building Code Requirements for Concrete Masonry Structures" (ACI 531-79), Chapter 10.

Supplemental allowable stresses and analysis techniques are specified in the Grand Gulf " Design Criteria for Concrete Masonry Walls in Category I Structures" (Appendix B).

2. Loads and Load-Combinations The loads and load combinations used in the analysis and design cf concrete masonry walls at Grand Gulf are equivalent to those listed in the SEB Interim Criteria. However, only dead loads, live loads, operating basis and safe shutdown earthquake loads, and tornado depressurization loads exist for the walls evaluated and designed at Grand Gulf.

3. Allowable Stresses For service load conditions, the allowable stresses specified in ACI 531-79, Chapter 10, are used in the analysis of the CMU walls for Grand Gulf Nuclear Power Station, and thereby conform with the allowsble stress requirements of the SEB Interim Criteria. Supplemental allowables are provided in the " Design Criteria for Concrete Masonry Walls in Category I Structures" (Appendix B). These supplemental allowables are determined by applying SEB Interim Criteria load factors to the ACI 531-79 allowable Stresses, for extreme environmental, abnormal. or severe load conditions.

In addition:

(a) No increase is applied to the allowable stresses for OBE seismic load combinations in the evaluation of CMU walls for Grand Gulf.

Units 1 & 2. This is in accordance with the SEB Interim Criteria.

(b) The analysis of concrete masonry walls at Grand Gulf uses the ACI 531-79 allowable stresses associated with special inspection during construction. Based on QA/QC records and the requirements {

of Specification 9645-A-004.2 (Appendix E), the construction of CMU j walls for Grand Gulf Units 1 & 2 generally complies with the requirements of ACI 531-79 and the SCB Interim Criteria.

l (c) Mortar joints in vertically reinforced masonry walls are assumed to resist no tension in the analysis of CMU walls for Grand Gulf.

The allowable grout tension stress is used in evaluating masonry walls which do not crack under design loadings. Use of the cracked section analysis outlined in the Grand Gulf design criteria (Appendix B) for reinforced maconry walls results 'in all tensile stresses ultimately being resisted by the reinforcement.

3 - __- - _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ - _ _

f In summary, all the block walls within the scope of the evaluation i at Grand Gulf have met the SEB Interim Criteria.

4. Design and Analysis Considerations (a) The analysis of concrete maronry walls for Grand Gulf, Units 1 and 2, follows established principles of engineering mechanfes and

, reflects sound engineering practices.

(b) The CMU walls are modeled using appropriate boundary conditions.

The evaluation considers cracking of sections and the dynamic behavior of concrete casonry unit valls. This is in conformance with the NRC Inte:im Criteria.

(c) The dynamic analysis of CMU walls for Grand Gulf used the following da= ping values: (in % of critical damping) ,

4 Operating Basis Earthquake (OBE) - 2%

Safe Shutdown of Earthquake (SSE) - 2% (uneracked section) 5% (cracked section)

I These da= ping values are lower than those specified for reinforced l concrete in Regulatory Guide 1.61, thereby being more conservative than the SEB Interim Criteria requirements.

I (d) The seismic analysis of concrete masonry walls for Grand Gulf. 1 Units 1 and 2, conforms to the commitments in the FSAR, Section 3.7, and the supplemental design criteria in Appendix B.

'. (e) .The analysis considers the combined effects of in-plane and out-of- '

plane loads.

(f) Interstory drift effects are considered in the evaluation and do not result in significant masonry stresses.

I (g) All concrete masonry wall construction in the Grand Gulf Control Building (Units 1 and 2) and Auxiliary Building (Unit 1) is complete.

(h) All concrete masonry shear walls at Grand Gulf, Units 1 and 2 conform to the minimum reinforcement requirements specified in Appendix A of ACI 531-79.

(i) There are no multi-wythe or composite CMU walls in the Control Building of Grand Gulf, Units 1 and 2. Where multi-wythe walls exist in the Auxiliary Building, composite action is not assumed.

I (j ) QA/QC information for the Grand Gulf CMU walls is available for NRC review upon request. '

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4

l (k) No concrete nasonry walls in the Grand Gulf Control Building (Units 1 and 2) and Auxiliary Building (Unit 1) are subjected to l accidental pipe break, jet impingement, or missile impact loads. '

Conclusions The evaluation is based on data obtained from the January 1981 and October, 1981 field survey of the Control Building (Units 1 and 2) and Auxiliary Building (Unit 1) CMU walls. All CMU walls, either as constructed or as modified, satisfy the SEB Interim Criteria load combinations and allowable stresses.

Attachments: 1. "SEB Interim Criteria for Safety Related Masonry Wall Evaluation" D

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