ML17340A956

Forwards Response to IE Bulletin 80-11, Masonry Wall Design. All Walls Have Been re-evaluated to Meet Intended Function Under Appropriate Loads & Load Combinations

ML17340A956
Person / Time
Site:	Turkey Point
Issue date:	04/03/1981
From:	Robert E. Uhrig FLORIDA POWER & LIGHT CO.
To:	James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
References
IEB-80-11, L-81-153, NUDOCS 8104130023
Download: ML17340A956 (18)

Text

I .V. t5VX 5 j81UVIVIIRIVII,t L 44 IQA FLORIOA POWER 5 LIGHT COMPANY r, 0/(

p g I April 3, 1981 L-81-153 II Mr. James P. O'Reilly, Director, Office of Inspection Region and Enforcement U.S. Nuclear Regulatory Commission

'QP//rp, 101 Marietta Street, Suite 3100 Atlanta, Georgia 30303 gpss~ Q~ +%I

Dear Mr. O'Reilly:

Re: Turkey Point Un s 3 &

Docket Nos. -25 and -25 18E Bulletin -11 Please find attached our final report. in response to ISE Bulletin 80-11.

Very trul yours, Robert E'. Uhrig Vice President Advanced Systems 5 Technology REU/JEM/mbd Attachment cc: Mr. Harold F. Reis., Esquire oR3 PEOPLE... SERVING PEOPLE

H

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r II

FLORIDA. POWER &. LIGHT'OMPANY.

TURKEY POINT PLANT UNITS NO. 3 & 4 MASONRY MALL RE-EVALUATION (NRC IE BULLETIN 80-11)

BECHTEL PONER: CORPORATION GAITHERS BURG,, MARYLQg)

MARCH, 198 1'

ABLE OF CONTENTS I. INZRODUCTION & CONCLUSION II RESPONSES TO OUTSTANDING IE. BULLETIN 80-11 ITEMS A., Item 2b B. Item 3 III REFERENCES

FLORID POWER & LIGHT'OMPANY THUG'Y POINT'LANT UNITS NO. 3 & 4 MASONRY WALL RE-EVALUATION (NRC- IE BULLETIN 80-11)

I ... INTRODUCTION 6 CONCLUSION This. report is submitted to complete FPL's. response. to'NRC IE. Bull'etin 80-11.

It: specifically addresses items "2b" and. "3". Responses to items, "1"'nd "2a" of'he bulletin have been'rovided to the NRC via letter'>>80-234, dated. July 24, 1980.,

The July 24, 1980 submittal indicated that 99 walls were to be re-evaluated.

However, further. review indicated that 97 walls are in proximity to ox have attachments fxom safety-related piping or equipment. Also that submittal indicated. the inaccessibility of the Unit 3 containment which precluded E

a walkdown. However, during a'recent outage, a walkdown was completed by a survey team, and no concrete masonry-walls'ere found in the Unit, 3 containment.

All, 97'alls have, been re.-evaluated to meet their, intended function, under the appropriate. 1pads and. load. combinations associated with these walls, based. upon the: methods and. criteria provi'ded. in, Section IZ of- this submittal. Two of :

these- walls were determined. to be inadequate-to withstand jet. impingement loads only. Nuclear- safety related function(s) associated with the remaining 95 walls are not adversely impacted. The two walls that could potentially fail have associated. with them one reactor trip channel Failure of the circuit will trip the. channel,. i.e., the. circuit fails safe., Thus,. the potential. loss of either oC the: two walls is. considered, acceptable because the potential. impact.

oN the facility does not: affect: the ability to achieve and. maintain; a, safe shutdown condition

II., RESPONSES TO I;E'. BULIZTIN 80-11 ITEMS A. Item 2b Masonry walls, at; Turkey Point', Plant'nits 3 and 4 typically serve as- partition wall's, fire.- barriers,, water; barriers flood barriers shield. walls; load'earing. walls; or sound. barriers.. Documents indicating,l'ocation, and'. layout of masonry walls- are available at. the Turkey Point. site. for NRC, review. ~

The types and. strengths of. materials for construction typically were-as follows:

(1) Concrete. block conforming to ASTM C-90-66-T Grade A, with linear shrinkage limited to 0.05 percent-.

(2) Mortar conforming to ASTM C-270-64-T, using type "S" for un-reinforced masonry in contact. with. earth, type "N" elsewhere, and. type: "M".for.'reinforced masonry.,

(3) Grout for; filling*concrete block cells conforming to type "M"

-with. maximum size of aggregate: of'/8 inch.

'(0) Reinforcement Bars conforming t'o ASTM A-15-66, intermediate grade, deformed.

Joint Reinforcement: Approved standard product (Dur-0-Wall) conforming to ASTM-A82-66.

Five.- multi.-wythe, masonry walls were identified.. A total of 87'asonry wall's; were. reinforced. and. a total of. 10 masonry walls were unreinforced'.

The. typical masonry wall. reinforcement. detail shows 84 or 85 verticaL reinforcing, bars, spaced. at 16 inches on center: and horizontal. masonry reinforcement of Dur>>O-Wall (or equal) spaced at either 16 inches or J

32 inches. on, center.. No masonry ties between the-wythes are shown on design drawings f'r multi-wythe walls.

TypicaI construction practices associated with these walls follow:

(1) Concrete"blocks'ere= stacked.'nder: cover oe protected from.

exposure" to~ the.. weather or from. contact. wi'th soi,l Use; oC damaged'l'ocks was not permitted.

(2) Mortar was prepared in batches of the volume that was to be used before initial set took place, and was placed within one hour after'mixing.

(3) Grout was mixed. in a. clean mechanical mixer. with only sufficient water added to produce a. plastic mix which would flow readily into place without segregation.

(4) Vertical reinforcing steel typically consisted of rebar dowels in. a. base. slab or. footing, lap spliced to vertical rebar in a grout. filled block cell.. The masonry blocks were placed. in a staggered pattern over the d'owels,. vertical rebar lap spliced to the. dowels, and horizontal. reinforcing placed at. specified l spacing; All. cells. including; those. containing vertical, bars

,were. grout. filled with the. reinforcing bars adequately. anchored in place until the grout had set sufficiently to support the bars.

(5) Unreinforced masonry blocks were placed. in a staggered pattern.

(6) Grout: was",=poured. in lifts. not, exceeding 16 inches. Each pour was, rodded to insure compaction" and bond to the proceeding pour and.'o prevent. the; development" of voids.

The construction practices employed adequately prevent. any significant.

voids. or: other. weaknesses in the materials of construction.,

All 97 masonry walls were re-evaluated. for their intended function based upon appropriate Turkey Point Units 3 & 4. FSAR loads and load.

combinations using conventional analytical methods prescribed by the Vorking Stress Design method with a load factor of. unity. The. loads.

considered included. those. produced from. safety and non.-safety-related attachments", interstory. drift: (differential, floor displacement),, thermal.

effects, and'he- effects of potential cracking. under dynamic loads The FSAR does not. specify the use of any particular. code for. the design.

of the masonry walls For: normal. design loading conditions the re-evaluation was based on the American Concrete Institute "Building Code Requirements for Concrete Masonry Structures" (ACI 531-79). For.

loading conditions not. directly covered. by this- code, supplemental allowable stresses and alternative design techniques were used as discussed hereinafter.

Calculated wall stresses were first compared against an allowable stress criteria. If allowable stresses were exceeded, then wall.

stability was checked using inelastic design approaches.

Design allowable stresses were used for- loads'ormally encountered, during plant- operation or shutdown (such as normal operating. thermal, effects and pipe. reactions) and. infrequently encountered loads (such, as operating basis earthquake (OBE) and'ind loads).. A. 30/: stress.

increase; was permitted for load combinations containing normal operating thermal effects or.. displacement limited loads. The factor of safety against failure of the masonry for cases where the 30% stress increase is utilized reduces from 3.0 to 2.3,. still well within the elastic range.

Allowable stresses utilized, in the re.-evaluation follow:

Masons~

All'owable working- stresses as per Table 10..1. of'CI'31-79.

Cell Grout Allowable tension stresses equal to 2.5 .

Reinforcin Steel Stresses in steel reinforcement not: to exceed the following limits: (ACI: 531-79):;,

ln: Tension:

Grade. 40 bars ...............,......,. 20,000 psi Joint. wire, reinforcement 50 percent of minimum ASTM speci, fied yield strength, but not to exceed ................... 30,000 psi In Compression:

40 percent of ASTM specified yield. strength, but not, to exceed ...............,.............. 24,000 psi In>>. plane. effects due. to interstory drift were either determined by.

analysis. or. in-. plane strains (A/H). They were limited t'o 0.00012, where His the relative displacement: between the. top and. bottom. of:

the: wall. and H is the height. of'he wall. A totally confined. wall was limited to a strain of 0.0008'or. walls where (a) the structural shear.

resisting elements bounding each vertical side of the wall had a shear, resisting capability larger than the wall and (b) the wall width to height ratio was at least 0.5.,

In-, plane: strain allowables for. interstory. drift. effects for non-shear walls were established below- the- level of: strain. required. to initiate.

significant. cracking. The. allowable: strain for. a confined wall was based. on the equivalent. compressi'on strut. model discussed in. Reference. 1 and modified. by a safety. factor of 3.0 against crushing. Test data.

(References. 1. through 7) associated with cracking strains for confined

/

masonry walls subjected to in-plane displacements confirms the predicted strain as given by the equivalent strut model.

Design.allowables. we increased for loads which are ghly improbable such. as. the safe, shutdown earthquake (SSE). Code allowable stresses for masonry in tension, shear and. bond were'increased by a factor of 1.67'hich provides a factor of safety against failure of 1.8. Masonry compression stresses were increased by a factor of 2.0 for axial stresses. and. 2 5 for; flexura1 and bearing stresses which provides a safety- factor; against: fail'ure oE 1..2; Allowable reinforcing steel.

stresses were<< 90%, of.'inimum ASTM specified yield. strength provided.

lap splice lengths. and, embedment: (anchorage) could devel'op this stress level.. Allowable, bond. stresses in determining. splice. and.. anchorage.

lengths were permitted to. be increased by a factor of 1.67..-.In-plane strains. due. to interstory drift were limited to 1.67 times the values previously stated..

Damping for uncracked walls was set't 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 crack due to out-of-plane seismic inertia loading were set at 4% for OBE and 7% for SSE.

The modulus of rupture of concrete, grout and mortar was assumed to vary by 20%5, therefore, a lower bound modulus of rupture was determined by applying. a. reduction factor of 0.8 to the theoretical concrete modulus of'upture of T.5 ~f'c. For mesoury,. th.e modu.lus of. rupture:

was approximated. by* increasing the. code. allowable flexural. tensile.

stress'y the factor. of safety of. 3 and then. applying the 20% reduction to arrive at a lower bound value of 2.4 Ft, where Ft is the. code allowable tensile stress.

Where. the bending due to out-of-plane loading caused flexural. stresses in the." wall to exceed the-. previously stated. design allowables,, the wall was evaluated by alternate methods. including the following:

Ener Balance Techn e Masonry walls (a) that were not relied upon to provide strength'f the structure as a whole, and (b) that were subjected to out.-of-plane. seismic inertia loading causing flexural stresses in excess; of design, allowables were evaluated by means of: the "energy balance; technique:" fom reinf'orced. wall's.

Reinforced: masonry wall's evaluated. by the "energy balance technique-"

(References. 8 and. 9) must: have sufficient'apability to preclude brittle failure an'd allow relatively large ductile flexural deformations. Tests (Reference 13) indicate that when flexure is the dominant. action,, ductilities are in excess of 25. Other:

tests (Reference 14) show that. when compression failures occur, ductilities in excess of 5 can be achieved.

When reinforced masonry has adequate shear and compression capability, its behavior is expected to parallel that of reinforced concrete where. allowabl'e. ductilities for predominately non-structural elements are normally set. at 10. 'hus, for out-of-plane seismic loading on. non-shear: wall's constructed. of masonry where brittle failures are. precluded,, a ductility of' was considered acceptable if:.the function of the safety system(s) associated. with. the wall are: not, jeopardized. by wall deflection.

The, deflection. of a fully cracked reinforced wall subj'ected to seismic loading was determined by the '"energy balance technique".

If the, predicted. displacement exceeded three times the yield displacement' the resulting displacement was multiplied by a factor.- of 2.. The resulting displacement was utilized to evaluate the: potential impact. on the function. of safety related system(s) attached. and/ox" adjacent. to, the..wall In; a11'ases- the= midspan displacement. was limited; to fi've times the, yield'isplacement, and the masonry compression stresses were limited. to 0.85f'm

Archin Action Masonry walls confined within a rigid frame or, structure can develop substantial resistance to out-of-plane loadings, after.

flexural cracking. These walls may be evaluated by use of the arching theory (References 10 through. 12).

The; resistance of the- wall to out-of<<plane: forces were, that: a;- three-hinged: arch'."'is: formed. after flexural determined'y'ssuming; cracking Due. consideration was given to the rigidity of the-supporting elements and their ability to restrict rotation of the wall about the supports. The effects of a gap at, the. supports were considered The maximum allowable uniform load used was the lesser. of.:

a) One third of the predicted load based on a maximum masonry compression of 0.85f'm b) Two thirds of the. predicted load based. on a, maximum tension stress of. 6 'm. along the 4.5 diagonal failure plane and.

one inch. bearing wi'dth at 0.85f'm'n the vicinity of'the hinge

-The: deflection at. the. interiom hinge: oK the. arch. after fulL contact.

with the, support: was-. limited". to- 0.3 times. the. thickness of the wall..

A. displacement. of. 2 times the calculated. displacement was utilized to evaluate. the potential, impact on the function of, safety related system(s) attached and/or, ad]acent to the wall.

The structural response of the. masonry walls subjected: to out-of-plane, sei'smi'c: i'nertia. loads'as. based. on, a. constant. value of. gross. moment of inerti'a" along"the. span, of the.. wall for. the. elasti'c (uncracked) condition..

If'he wall. was- cracked', the moment oE'nertia. was. obtained. by using the ACI-318 formula for effective moment. of inertia used, Sn calculating immediate. deflections (Reference. I 15).

To determine: the out- -plane frequencies oF masonry lls, the uncracked behavior and, capacities of. the. walls and, iF applicable, the cracked behavior and capacities of the walls were considered.

Uncracked Condition The equivalent moment= of inertia oF an. uncracked wall (It) was obtained from: a- transformed', section consisting" of the block, mortar, and ce11 grout".. Al'ternatively, the cell grout,, neglecting block and mortar. on the. tension side, was used..

Cracked Condition If the applied moment due to all loads in a load combination exceeded the uncracked moment capacity, the wall was considered.

to be cracked. In this event,. the equivalent moment of inertia was computed as follows:

Ie M cr M cr cr M M a<< a M

cr' t.

Y.

where, Ie, = Equivalent. moment, of 'inertia M = Uncracked. moment capacity cr M = Applied maximum moment on the wall I' Moment of inertia of transformed uncracked section Icr. ='oment of inertia of'he cracked section Fr = Modulus; oF rupture Y = Distance of neutral plane= from- tension; face.

If the use. of an equivalent moment 'of inertia, resulted in an applied'oment less than the uncracked moment capacity, then the wall was verified for the uncracked. capacity.

The efFect of modes vibration higher than the fun entaL mode was- considered. For this purpose, a modaL'nalysis was,performed or.- alternatively,, the inertia. load on the wall due to its own weight for. the fundamental mode was'onsidered as the uniform load in lieu of, determining an effective. mass.. The, corresponding bending moment and. reaction account: fom the higher mode effects.

Vncertainties in; structural frequencies. of. the: masonry walL due. to variations in structural properties and mass were- taken into. account.

The lower.- bound'requency was utilized if it was, on, the higher,- frequency side of the peak response, spectrum. If the lower bound frequency was. on. the lower frequency side. of the peak, the peak acceleration was used.. If'he response spectra for a wall spanning between two floors were of the same shape, the average spectra was used. If they were different, the enveloping spectra was used corresponding to the walL's natural frequency.

Boundary conditions were determined considering one-way spans with hinged, fixed or free edges as appropriate. Two-way spans were not used.,

Load transfer. at the boundary was evaluated based on boundary anchorage 1

capacities.. Fixed. end. conditions were justified for. walls (a) built into thicker, walls or, continuous across walls and slabs, (b) that, have the. stxength to resist. the. fixed end moment, and (c) that have sufficient.

support rfgidity to. prevent rotation. Otherwise, the wall edge: was considered simply supported or free depending on the shear carrying.

capability of the. wall and support..

Distribution. of concentrated loads are affected by the bearing area under. the. load, hori'zontal and vertical wall stiffness,. boundary conditions'. and. proximity-. of: load to wall. supports~ For predominantly one-way action,, an effective beam width of 6 times the- wall, thickness for: distribution: of, concentrated'oads was" conservatively used, for.. the following, condi,tions:

Concentrated, load at midspan;- simple supports:

~ LP 9.6T Concentrated load on a. cantilever: h

+2.4T'.+4.8T Couple at midspan;, simple. supports:

Couple near a support,. simple supports'. a+ Z.4T L'

where.- beam., length h:. 'istance= from~ the- fi'xed. end to the. point. of load application.

a. = distance between: the concentrated loads producing a couple T = thickness of the wall Interstory drift'alues were derived from the dynamic analysis. Strain allowables depending on the degree of confinement were applied for in-plane drift effects on non-shear walls. They were set based on in-plane effects in a manner that ensures that a reasonable margin remains for. out-of-plane loads. Out-of-plane drift effects were considered if some degree of fixity.existed at the top and/or. bottom of the wall.

Local loadings, resulting from items such as piping and equipment support. reactions, were included.. The evaluation included. transfer.

oE the 1'oads" into the: wall by consideration of, punching shear. effects to:-ensure that. failure; due. to. local. effects, (X..e., block pullout) would," not occur.

The're-evaluation of multi-wythe masonry walls was based on. the absence of composite action between the two wythes.

B., Item' The. methods and. assumpti'ons- utilized, in. the.. masonry- wall. re-evaluation.

were.. based. on. conservative. acceptance criteria and referenced literature which provide adequate. support'. for the propriety of the evaluation methodoIogy., Therefore;. there=- is no need; to. conduct. a= masonry wall test: program; to support: the. re-evaluation. conducted pursuant to NRC Bulletin 80-11;,

REFERENCES Klingner,, R. E. and Bertexo, V. V., "Infilled Frames in Eaxthquake Resistant Construction,." Report No., EERC 76<<32, Earthquake, Engineering Research Center,. University of. California, Berkeley, CA, December.;, 1976.

Mali,, R and,"Salgado,, G.. "Comportamiento. de muxos de. mamposteria. sujetos a cargas 1'aterales,," (Behavi'or of." Masonry Wall. Under. Lateral. Loads.

Second-Report ) Instituto>> de: Ingenieria, UNAM,. Informe No. 237, September;,

1969..

MeH; R , Zeevart;, W'.. and.'Esteva L' "Comportamiento de muros de. mamposteria hueca ante cargas alternades," (Behavior. of Reinforced Masonry Loads), Instituto de Ingeniexia, UNAM, Informe No.156, July, Undex'lternating 1968.

Chen, S. J., Hidalgo, P. A., Mayes, R. L., Clough, R. W., McNiven, H. D "Cyclic Loading Tests of Masonry Single Piers, Volume 2 - Height to Width .

Ratio of. 1," Report'o. EERC 78-28, Earthquake Engineering Reseax'ch Center, University of California, Berkeley, CA, November, 1978.

Mainstone, R. J., "On the. Sti.ffnesses and Strengths of Infilled Frames,"

Proc.. I.C.E , 1971.

Hidalog, P. A., Mayes, R . L,, McNiveny H D p Clough' W p Cyclic Loading., Tests of Masonry. Single Piers, Volume. L - Height: to Wi.dth Ratio of. 2,." Report. No.. EERC 78/27, Earthquake Engineering;Research Center,. University of California, Berkeley, CA, 1978.

Hidalog,. P'. A, MayesR L McNiven, H'. D.Clough, R W, "Cyclic Loading Tests of. Masonry Single. Piers, Volume;= 3 Height: to Width Ratio of 0 5 .'eport No EERC- 79/12 Earthquake. Engineering. Research Center, Univexsit~ oE C'alifornia, Berkeley;. CA, 1979..

BlumeJ.. A,. N M'ewmark, and L. H. Corning,, "Design of Multi;story Reinforced Concrete Buildings for Earthquake Motions," Portland. Cement Association, IL. 1961 Newmark, N.. M ,. "Current. Trends in the. Seismic; Analysis and Design of'igh-Rise Structures," Chapter 16, Earthquake: Engineering,. Edited by R'. L., Wiegel, McGraw-Hill',, 1970.

Gabri.elson;, B;. L'.. and; K; Kaplan,. "Arching. in: Masonry. Walls Subjecte*

to; Out-of.>>Plane Forces,." Earthquake. Resistance. of. Masonry Construction, National Workshop NBS 106;, 1976;. pp 283.-313.,

McDowell,. E.. L., K E.. McKee; and. E'avin"Arching Action Theory.

of Masonry Walls,," journal. of the Structural Division,. ASCE Vol 82',

No ST2March,.1956',Paper No .. 91'5'..

-12>>

. 12. McKee,, K'., E. and'., Savin~esign of Journal', of the Structural ~ision,.

Masonry Walls for, ASCE.

B~ Loading;"

Transactions, Pro~eding Paper 1511,. January, 1958.

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

Bulletin. of New Zealand Society for Earthquake Engineering, Vol. 5, No., 4-,, December, 1972.

14.. Scrivener, J.. C , "Face. Load, Test's on Reinforced. Hollow.-brick. Non-.

loadbearing. Walls," New Zealand. Engineering, July 15, 1969.

15- Branson,. D.. E , "Instantaneous'nd; Time-Dependent" Deflections on; Simple and. Continuous. Reinforced Concrete Beams,," HPR Report. No. 7, Part 1', Al'abama.,Hi'ghway Department, Bureau of Public. Roads, August 1965, pp.. 1-78.