ML13316B809
| ML13316B809 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 11/10/1980 |
| From: | Haynes J Southern California Edison Co |
| To: | Engelken R NRC Office of Inspection & Enforcement (IE Region V) |
| References | |
| 80-334, IEB-80-11, NUDOCS 8101050074 | |
| Download: ML13316B809 (21) | |
Text
Sout ern California Edison Company P 0.
800 S9C 24 WALNUTF GROVE AVENUE ROSE.lEAD. CALIFOR IA 9 1770 Noveber10, 1980 U. S. Nuclear Regulatory Commission 1
Attention:
R. H. Encelken, Director Orfice of Inspection and Enforcement e
RCio 0n V Suite 202. Walnut Creek Plaza 1990 North California Boulevard Walnut Creek, California 94596 Centlemen:
Subject:
Docket No. 50-206 IE No. 80-Il, Masonry Wall Design San Cnotre Nuclear Generatino Station Unit I Ycur letter of Mav 8, 1980, forwarced the subject IE Bulletin for our action. Part oF' the requested information was provided by our letter dated July 17, 1380. The additional information requesteo in item 2.b of the Bulletin is proviced as an enclosure to this letter.
I u have any questions on this information, please contact me.
uosc-ric on tnics m;cy of
._______1980.
oil_
01 1580
- i.
G. Haynes /
1-Manager of Nuclear Operations Subscribeui and sworn to before me
)
this
,/9day of ~V<~ ~j,1980.
om &CIAL SEAL AGNES CRABT1HE NOTARY F OUC - CALIFORNIA
- 19.
PRINCIPA. OFFCE IN LOS ANGELES COUNTY My Commission F7p. AIM.27.1982f NotayY Public in and for the County of' Los'/Angeles, State of California Enclosure cc:
NRC U t ce of Inspection nd Enftorcement (Washington, D.C.
8101 0 500D
S.
Enclosure iSPONSE TO ITEM 2.b OF NRC IE BULLETIN NO. 80-11 ENTITLED "MASONRY WALL DESIGN"
References:
SCE letter.dated July 17, 1980 to the Director of the Office of Inspection and Enforcement, Region V;
Subject:
Docket No. 50-206, IE Bulletin No. 80-11, Masonry Wall Design, San Onofre Nuclear Generating Station, Unit 1.
"Research Data and Discussion Relating to Specification for the Design and Construction of Load Bearino Concrete sonry," NCMA, 1970.
C. "A State-of-the-Art
- Review, Masonry Design Criteria,"
Computech Engiheering Services, Inc., June, 1980.
Item 2b(i)
Descrioe, in detail, the function of the masonry walls, the confiourations of these walls, the type and strengths of the materials of which they are con structed (mortar, grout, concrete, ano steel),
ano the reinforcement details (horizontal steel, vertical steel, and masonry ties for multiple wythe construction).
A wythe is consioered to be (as defined by ACI Standard 531-1979) "each continuous vertical section of a wall, one masonry unit or groutea space in chickness ana two in. minimum thickness."
Resoonse:
The masonry walls at Lian Onofre Nuclear Generating Station, Unit 1, are located anu idencified on the enclosed sketch SK-C-CO.
Those masonry walls which are in proximi y to cr hae attachments from safety relatea piping or equipment are on-in cctil on the enclosed sketches SK-C-002 through SK-C-O2.
Tis set of sketches also shows the safety and non-safety related items attachnd to the wall and the safety related equipment in proximity to the wall.
Also icentifice on sketch SK-C-001 are walls which are not in proximity to or do not have attachments from safety related piping or equipment.
These walls are:
- A61, 5 2, S64, SL7 through SB15, the two hose houses and the lube oil storace ocuse.
Of these. walls,
- AB1, SB2, SB4 and SB7 are evaluated (see table 1) since they have structural steel beams connecting them to masonry walls which have safety related equipment in their proximity.
The remaining masonry walls,re not evaluated since their collapse would not affect any safety relatec items or structures.
Walls ABI and AB2 have 1/2 inch thick nonstructurail cIecorative marble veneers attached to their outer face.
The weight of these veneers is included in the analysis of AB1 and AB2.
- However, since the veneers are not in the proximity of safety related items, they are not evaluatea.
Similarly, there is a two inch thick split face concrete veneer attachea to the outer face of a concrete wall in the control building.
This veneer is not evaluated as it is located away from any safety related items.
All of. the masonry walls are single wythe walls, constructed of Grade N (formerly Grace A) hollow concrete masonry units.
Type S grout and Grade 40 reinforcingbars were utilized in the construction of the walls.
With the exception of walls AE through AB6, all masonry walls consist of eight inch block.
Wells PE4 through AB6 consist of six inch block.
The turbine huilding enclosure walls (TB1 throuch TBl2) consist of approxi mately three hundred linear feet of masonry walls with a height variation from approximately ten to twenty feet.
These walls are nonstructural walls whose function is weather protection. With the exception of the northernmost wall (Tl12), all of the turbine builcir walls are laterally supporteo at the top by the structural steel framing of the turbine building. Reinforcing consists of No. 5 bars at 32 inches vertically and No. 5 bars at 48 inches horizon tally, except wall TBl2 whose vertical reinforcement is No. 5 bars. at 24 inches with horizontal reinforcina -of No. 5 bars at 48 inches.
The cells containing vertical reinforcement are fully oroutec as are the blocks contain ing the horizontal reinforcement.
In acoition, each wail has two No. 5 horizontal bars in the too course to serve as a oond beam.
The masonry walls in the fuel storage ouilding (FBI throuch FB) consist of approximately four nunored linear feet of wall with heichts of approximateiy 22 to 27 feet.
The 27 foot hich walls have.an intermediate lateral support which is provideo by steel roof decking, concrete slabs and/or structural steel framing.
The structural steel framing system carries the vertical load ana the masonry wails carry la.erai snear forces.
Reinforcing in the fuel storage bulicing consists or No. 7 vertical bars at 32 inches ano No. 5 horizontal bars at 48 inches.
Al1 cells ano blocks containing reinforcing are fully groutec as are all ils in the bottom three courses of all wails.
in addition, bond beams i' -< ceep with two No. 5 bars top ano bottom occur at all elevations at nich the walls are laterally.supporteo.
The ventilatn, c u
i is a rectangular masonry structure approx imately 20 by
-0 et in plan and approximately 20 feet hiQh.
The roof consists of ste-l 1c 3ig supported by steel framing which in turn is supported by the Rescnry,alls.
The masonry walls (Vbi through VB4) are therefore vertical load bearing shear walls.
Reinforcing steel, bond beams and grouting are he m as the fl storage buildino.
The only porItin of the rector auxiliary building. completely above grace is the northeaSt corner.
This portion of the building is approximately 30 by 40 feet in plan stoning from 15 to 22 feet high.
It consists of both concrete anc masonry,iils and steel roof decking with an intermediate floor consisting of a ncncrete clab in one portion of the structure.
The masonry walls (SB1 throuch S7) erve as both vertical load bearing and shear walls.
Vertical reinforcing varie-from one No. 5 bar spaced at 48" on center to No. 5 bars at each face
,pace t 8" on center.
Horizontal reinforcement is No. 5 bars at 48".
All cells and blocks containing reinforcing bars are fully groutea.
Two foot omep nonc berro with two No. 7 bars top and bottom exist at the roof and at the intermeciate floor elevation.
The control building contin six reinforced masonry walls (ABl throuch AB6).
Three of theswa r
in the eastern portion of the building which is the single story portion of the building. These three walls are 20 to 25 feet in length and 12 to !A feet high.
All three walls are both vertical load bearing and shear wvalls.
All-three wlls support the concrete slab which serves as the roof for this portion of the building The vertical reinforcing consists of No. 4 bars at 24" on center and the horizontal reinforcement consists of Dur-o-wall truss design type S wire mesh.
Cells containina reinforcement are fully grouted as is the bottom two feet of each wll. In addition to these walls, three masonry walls are located in the control room area at elevation 42'-0".
The walls are attached to 2'-10" thick reinforced concrete shielding walls and their function is to provide additional biolocical shieldino for the control room operators.
The walls are fully grouted 6" thick masonry with No. 4 vertical bars at 32" and No. 3 horizontal bars also at 32".
These masonry walls are fastened to the 2'-10" reinforced concrete shielding wall with 1/2 inch
'Vei-it anchors in an off-set orid pattern with a vertical distance of 2'-3" to 2'-8" between ancnors and a horizontal distance of 5'-4" between anchors.
These are nonstructural walls.
Item 2b(ii)
Describe the construccion practices employee in the construction of these
- walls, and in particular, thneir acecuacy in preventing significant voids or other weaknesses in any mortar, grouc, or concrete fill.
Resoonse:
An extensive searcn ws unuetaken to gahcr ano review all existing documen tation relate6 to Che construccion prac ices employed in the consctuction of the masonry l
inu hecllowlinQ areas:
i) the San Onofre Unit 1 project iles consC Ing of the recoros retention facility and the Documenc ac LaaE,ontfol Cener ac echt el Power Corporation (the general construction conrcor. t n
nofre UniL 1),
- 2) the Southern California Edison Gocument control facility at the station, and 3) the testing facility, Twining Laboratories.
The following cocuments -ere obtained ane reviewed:
(1)
Specification S-il2, Concrete Block iasonry At San Onofre Nuclear Cenerating Station, Unit 1 (2)
SpecircIon Ci0-261, RIeinfcrcing Steel At San Onofre Nuclear Generating Station, Unit 1 (3)
Specificion 0-253, Testing Laboratory Services At San Onofre Nuclear Cenerating Station, Unit 1 (4)
Twlninr Labortories Laboratory deport, entitled, "Hollow Lead Bearing Units, Examination No. S65-2888."
It was determined that S and W Masonry of Anaheim, California (who is no longer in business),
ccnstructed all of the original masonry walls in the latter half-of 15 under the requirements of Bechtel Corporation Specifica tion ESO-112.
In pat, the specification requires that "all work of this subcontract will h subject to continuous inspection by the Contractor or Owner" and it Sco so ecifies that "Specimens of mortar and arout shall be prepared for testing" and the testing shall consist of a minimum of "two...
test cylinders from each two cubic yards of mortar (or grout) placea per day."
Twinino Laboratories of Santa Ana, California was under contract to perform the testing on masonry blocks, mortar, grout, and reinforcing steel in accordance with Bechtel Corporation Specification BSO-253.
The Twining Laboratories report on Hollow Load Bearing Masonry
- Units, Examination No. S65-2888 stated that the masonry block units had met the specifiec ASTM C-sO, Grade N stanra.
The five masonry blocks tested averaged 1.333 psi (based on cross area) - weii acove the 1.000 psi recuired minimum.
Although no oocumentation was Tound to verify that during construction there was continuous inspection.
as requirco Dy the specification, it was the practice of Becnzei Corooration, the general contractor, to assign a field enaineer to succontracrors such as the masonry contractor to verify that the requirements of the specification ano orawings were being complieo with.
Reinforcing steel w;as purchasec by bechtel.
Each shipment of reinfcrcing steel to tne joosce required Lwo sets or certified mill test reports verifying the qua y
o te seel n accoroance with the requirements of Bechtel Corporation Specifi _cation AtSD-261.ocin Bt the jobsite, the reinforcing steel uncerwuvLtnz es
-,L V it-ninq Laos within the guidelines or Bechtel Corporazion,paciiJLcuon 63 3.
To further v-,ir i
En1 E sonry w als w ere constructed in accordance with the design sc c
ons and rinos, a team of Bechtel engineers conducted a survey -C c;m-i
=1 ton of reinforcing within the various walls.
Using a macgiO c
lc L0ater (or febar finder),
the horizontal and vertical reinfrcing steel was located in various representative walls ano compared to inforMation in the original design drawings.
For example, the finder indicrr ated a
orl 3 cnt ined vertical reinforcing steel spaced at 32" on center ana horizontal steel at 48" on center.
This agreed with the reinforcing steel specing detailed in the design orawing.
Ten different walls were examined; specifically
- TBl, TB5,
- TB7, T5ll, FB8, FB9, FB10, S6l, and VB2.
The survey team ccncluded that the field verified as-built configuration is in conformance with the requirements of the design drawings.
It is ccnluced that construction practices (continuous inspection, material testing ana sarpling,, etc.)
were employed in the construction of the masonry walls to F-nsure quality workmanship.
Item 2b(iii)
The re-evaluation report should incluce detailed justification for the criteria usec.
References to existing codes or test data may be used if applicable for the plant concition.
The re-evaluation should specifically adoress the followin:
(a)
All postulated loacs and load combinations should be evaluatea acainst the correspondinc re-evaluation acceptance criteria.
The re-evaluation should consicer the loads from safety ano non-safety related attach ments, differential flodr displacement ano thermal effects (or detailed justification that these can be consioered self limitinG and cannot induce brittle.failures),
and the effects of any potential cracking under dynamic loads.
Describe in detail, the methods used to account for these factors in the re-evaluation and the adequacy of the acceptance criteria for both in-olane and out-of-plane loads.
(b)
The mechanism for load transfer into the masonry walls and postulated failure moces shoulo be reviewec.
For mulirple wythe walls in which composite Denavior is reliec upon, cescribe the methoos and acceptance criteria usea to assure that these wails will behave as composite walls, especially with recaro to shear and tension transfer at the wythe Inzerfaces.,
With regaro to loca' loadings such as piping and equipment support reactions, the acceptance criteria should assure that the lCes are acequacely transferred into the wall, such that any assumptions regaroing the behavior of the walls are appropriate.
Induce tn pocencial for oiock pullour ano the necessity for tensile stress transfer through bond at the wythe interfaces.
ResDonse:
The criteria uo we re-+/-valuaon o1 masonry walls at SONGS 1 for non-seismic loacs is inclLce chment A.
The seismic re-evaluation of these walls will be ncuCt aC part of the Balance cf Plant Structures Seismic Reevaluation Program as indicateCd in Reference A.
The allowable ouresses given in Attachment A are basea on allowable stresses given in AC 571-79.
As stated in this publication, factors of safety for these allowable stresses are cenerally greater than three.
Experimental corroboration of this statement is provided by the National Concrete Masonry Association in Reference B. Consistent with ACI 531-79, a one third increase in the allowable stresses is taken when wino load is included in a load combination.
The results of th calculations performed in accordance with Attachment A are summarized in Table I. The load combinations presented in Attachment A and reflected in Table 1 are consistent with those loads adoressed in the San Onofre Nuclear Generatina Station Unit 1 FSAR.
None of the masonry walls are subject to thermal loads.
Additionally, since this response acdresses only non-seismic loacs, differential floor displacements and cracking due to
dynamic loads a7 either nonexistent or of such a small magnitude that they are necligible.
In-olane shear forces cue to wind loadinc do not exceed 10 psi in any-location.
Fven when the presence of the horizontal shear rein forcement is ignored, this value is well uncer one fifth of the allowable in-plane shear stress.
Block pullout end local. transfer of loa was also investicated.
Based on a mortar shear strength of 1L0 psi (1.1 I fm' where fm' 1,350 psi) anG a block without crcuted cells, it would take approximately 4,700 pounds to pull out a sincle block.
This value is almost 20 times the maximum value of any out-of-plane concentrated force from non-seismic forces (the maximum such force is a pipe reaction of acoroximately 250 pouncs on wall FEB10).
In summary, all the masonry walls at San Onofre Nuclear Generating Station Unit I meet the criteria for non-seismic loads as stateo in Attachment A.
The criteria and calculations were cevelcoec on the basis of a number of conservative enoineerino assumotions.
Amonc these conservative assumotions ano proceoures are:
all suoports are consicerec to act as pin connections, only vertical one way action is considereO. an all conouits are consioereC to be full.
in accition, no crecit was taken Tor interactive effects despite experimental cata wnich shows appreciative increase in out-of-plane moment capacity for axiaiLy loacea walls (Reference C).
These factors coupled with the hioh racor or sarecy associateu with the alluwable stresses proviue a conservative basis for the analysis.
TABLE 1 Page 1 of 4 AXIAl-AND. FLEXURAL STRESSES IN MASONRY WALLS FOR NON-SEISMIC LOADS AX1AL COMPIIRESSIVE' FitA*LL.
C P1.iESSIVE SITV SsS
.FIY.XURAL TfiSILE STESSES IN STRE-SSES IN HAS C.Y i:
AS REINFOSC1 NC SIEIL fa is fF-!f 1.33 F-f:.
fs F S f
1.33 Fs Va11 D+L D+L+ToIR Allo.
L4L LtT J Allat+/-d 0+1.A7 Alla..ed DIL D+L+To+R A1oj.,Ad DLil Allo-.ed building I.D.
(psi)
(psi)
(p-i)
(pi) (pd)
(psi)
(pii)
(p)
(i)
(kai)
(ki)
(Lai)
(vii)
TBI 27 27 160 49 49 450 481 600 2.7 2.7 20.0 26.7 26.7 TB2 24 24 250 45 0 200 (00 20.0 11.1 26.7 TB3 24 24 250 450 200 600 20.0 11.1 26.7 TB4 24 24 250 450 200 600 20.0 11.1 26.7 o
TB5 24 24 160 450 432 600 20.0 24.0 26.7 z
TB76 26 26 160 38 38 450 470 600 2.1 2.1 20.0 26.1 26.7 TB7 25 25 160 38 38 450 470 600 2.1 2.1 20.0 26.1 26.1 TB8 24 24 250 450 200 600 20.0 11.1 26.7 TB9 30 30 170 450 405 600 20.0 22.5 26.7 TB1O 30 30 170 450 405 600 20.0 22.5 26.7 TBll 30 30 170 27 27 450 432 600 1.5 1.5 20.0 24.0 26.7 TB12 22 22 170 107 107 450 471 600 5.1 5.1 20.0 22.4 26.7
- 1. In no case does vind load contribute to axial ccmpreaicn (for auial D+1W = D+L).
TABLE 1 Page 2 of 4 AXIAL AND FLEXURAL STRESSES IN MASONRY WALLS FOR NON-SEISMIC LOADS AXIAL. CCliPRESSIF 1'a..C 1;SIK V
STRESSES FLEXURAL TEllSILE STHESSES IN SfRESSES IN MASO Y(
1ASKOY REliFORCInG STEEL.
fa fa FS ft 1.33 Pu is fs F3 fa 1.33 Fa V1Wall DfL D+L4ToR Allo
-d D+L 1L30"T.1 Allouad DLUW Allo.;ed DIL D+L+Toth Alloved DHL+U Allowed Building I.D.
(psi)
(psi)
(pai)
(pSI)
(Pi)
(psi)
(psi)
(psi)
(L1)
(ksi)
(bi)
(kst)
(ki)
FBI 35 35 130 450 394 600 20.0 14.6 26.7 FM2 25 25 130 450 394 600 20.0 14.6 26.7 FB3 25 25 130 450 394 600 20.0 14.6 26.7 FB 25 25 130 450 394 600,
20.0 14.6 26.7 FBS 25 25 130 450 394 600 20.0 14.6 26.7 FE6 35 35 130 35 35 450 429 600 1.3 1.3 20.0 15.8 26.7 VB7 25 25 130 450 394 600 20.0 14.6 26.7 kFB 65 65 220 450 173 600 20.0 6.4 26.7 FB9 68 69 220 122 230 450 230 600 4.5 8.5 20.0 8.5 26.7 FBl0 65 72 220 26 165 450 338 600 1.0 6.1 20.0 12.5 26.7
- 1. In no case does wind load contribute to axial ccpreroion (for eial D+LIW = D+L).
TABLE 1 Page 3 of 4 AXIAL AND F LEXURAL STRESSIES IN MASONRY WALLS FOR NOH-S ELISIC LOADS AXIAL CoWlim lv I1An LivS;iss: ST-A-lS FLEXURAL TEllSI.E SITESSES Ili I, SIREssEs ii HAso(1 i
80:0 RElb.FO1CING STEEL fa a
Fa Lij i
i L
1.33 ft-Li fLi3 L3
- 1. 33 Fz
%4,1 Dall L D L+ 0 Alowd Aod L
L-L:'
AlD Ini
- 11)
Lii. D+L+TotR AlF o:d D'U Allued Bu iI ding I.D.
(psi)
(p)
(rpfi)
(pi)
(p)
(p;)
(pt)
(pui)
(i)
(ksi)
(kit)
(ksi)
(Ii)
SM 27 27 240 19 19 450 305 600 1.3 1.3 20.0 21.3 26.7 SB2 27 27 240 450 26 600 20.0 20.0 26.7 SB3 50 50 280 38 3L 450 165 600 2.7 2.7 20.0 11.6 26.7 SB 27 27 240 50 286 600 20.)
200 26.7 SB5 17 17 290 450 83 600 20.0 5.8 26.7 S136 48 48 280 450 127 600 20.0 8.9 26.7 SB7 25 25 240 450 600 20.0 26.7 VBI 38 38 190 74 74 450 368 600 2.7 2.7 20.0 13.6 26.7 VB2 38 38 190 74 74 450 368 600 2.7 2.7 20.0 13.6 26.7 V
VB3 38 38
.190 74 74 450 368 600 2.7 2.7 20.0 13.6 26.7 V14 38 n38 190 74 74 450 368 600 2.7 2.7 20.0 13.6 26.7
- 1. In no case does wind load contribute to tzial co,-prL-ouioa (for azial D 14'J DtL).
TABLE 1 Page 4 of 4 AXIAL AND FLEXURAL STRESSES IN MASONRY WALLS FOR NON-SEISMIC LOADS AXIAL CHFRESSI VE FLE-U:..L COMPiESSI-E STHESSES FLEXURAL TNESILE STRESSES IlI SITESSES II I
RY IL'.
u.sO REl JFOHCING STEEL f
f a.
Fu-ft, 1.33 F1 fL, fS fa 1.33 F&
lWall D+L D+ L+To*r( Allandj D+L i;LJTc2.iloedD+Z\\
Allound BL D+L+To4ft Allowd D+L+U;1 Allo ;ed Building I.D.
(pLi)
(psi)
(pi)
(pi)
(
(
1 pi)
(s i)
(pui (pc)
(Li)
(ksi)
(kii)
(1zi)
(L;i)
ABI 48 48 260 -
450 183 600 20.0 11.3 26.7 AB2 29 29 260 450 183 C00 20.0 11.3 26.7 AB3 52 52 250 63 63 450 63 600 3.9 3.9 20.0 3.9 26.7 kB4 5
5 290
-0.-
450 600 20.0 26.7 ABS 8
8 290 52 52 450 52 600 8.2 8.2 20.0 8.2 26.7 AB6 5
5 290 450 600 20.0 26.7
- 1. In no case does wind load contribute to axial coiprzLssion (for exzial DL+W DiI.).
At t ahifnnt "'A" SAN 0 OFRE
.U CEl GNRTING, STATION WNIT 1
~~LUTIOHCRITERIA FOP,
-AC~Y WALLS (E::LUDING SEISMIC LOADS)
JO 400074 NovemrbcT 4, 1980
EEVALUATION CRITERIA FOR.
HASONRY WALLS Table of Contents Page 1.0 Introduction and Scope.
1.1 Introduction 1
1.2 Scope.
2.0 Governing Code......................
..1 3.0 Evaluation Requirements
.1 3.1 Masonry Wall Identification.
1 3.2 Reevaluation Procedures.
2 4.0 Loads and Load Cominations.
4.1 Dead Loads.....................
2 4.2 Live Loacs..
2..
4.3 Electrical Components, Equipment and Piping Loads
.2 4.4 ind Loads....................
2 4.5 Load Combinacions.
3 5.0 aterials and Allowable Stresses.
3 5.1 aterials 3
5.2 Allowable Stresses..
5
1.0 INTRODUCTION
AND SCOPE
1.1 INTRODUCTION
Masonry walls whose failure could detrimentally affect the safety-related functions of safety related structures, systems and/or components in operating nuclear power plants are to be identified and reevaluated in response to NRC IE Bulletin 80-11.
1.2 SCOPE Presented here are the criteria that will be used for the reevaluation of non-seismic loads on the masonry walls at San Onofre Nuclear Generating Station, Unit One. The types of loading considered are those loads identified in the Final Safety Analysis Report (FSAR).
The reevaluation will determine whether the masonry walls and/or the safety related equip ment and systems associated with the walls will Derform their intended safety related function when sub jected to the FSAR loads and load combinations. Evaluation of the walls' structural adequacy shall include a review of local transfer of load from the block into the wall.
2.0 GOVERNING CODE The American Concrete Institute's pubication."Building Code Requirements for Concrete Masonry Structures (ACI 531-79) will serve as.the basis for the allowable stresses.
3.0 EVALUATION REQUIREMENTS 3.1 M-ASONRY TJALL IDENTIFICATION Masonry blcuC a 1-iicOSe iure could detrimentally affect the safety related function of safety related items will be subject to this masonry wall design reevaluation.
SpecifIcally a masonry block wall will be reevaluated if (1) there are safety related items attached to the wall or (2) there are safety related items within the proximity of the wall.
Proximity is defined as that area described by the imaginary rotation of the wall in question about a longitudinal axis through the wall's lower support point until the wall is horizontal.
The height of the wall to be subject to this imaginary rotation is the distance to the first lateral support point above the support point of rotation.
Masonry walls meeting the above definition are located in the following buildings:
- 1.
Reactor Auxiliary uilding
- 2.
Fuel Storage Building
- 3.
Control Building
- 4.
Turbine Building
- 5.
Ventilation Equipment Building These buildings and the associated masonry walls are described in reference 3.
3.2 REEVALUATION PROCEDURES The load cases given in section 4.0 will be evaluated by static analysis methods.
In order to assure a conservative analysis, one-way action will be assumed for out-of-plane loads, simple support conditions will be assumed at the floor connections and foundations, and out-of-plane concentrated loads will be distributed over six times the nominal thickness of the wall.
4.0 LOADS AND LOAD COMBINATIONS 4.1 DEAD LOADS Dead load consists of the weight of the walls, roofs, slabs, steel framing, and permanently attached equipment and other components.
Masonry walls are not subject to hydrostatic loads or buoyancy forces and therefore these loads will not be considered.
4.2-LIVE LOADS Live loads consist of any movaole equipment loads during normal plant operation and otner loads which vary with intensity and occurrence, such as floor occupancies.
A minimum live load of 50 lbs/ft2 will be used for floor slabs unless it is determined that a smaller live load is appropriate.
Roof live load will be 20 lb/ft" which is in accordance with the FSAR.
4.3 ELECTRICAL COMIPONENTS, EQUIPMENT AND PIPING LOADS In general, l Uue to attached equipmant, cable trays and conduit are small.
In ordler to conseryatively estimate the maximum effects of eccentric loads, aa evaluation of.field sketches of support geometry and location is conducted for each attached itom.
Ais a result of this evaluation a maximum applied mnioment is calculated based on the distance from the center of the masonry wall to the location of the applied load.
This moment is dis tributed over six times the thickness of the wall and is assumed to be coincident with the maximum mcment due to wind load.
The total vertical axial load due to attached items will be calculated from field drawings and applied as a uniform load. Weights of electrical trays and conduits used to calculate the maximum applied load are conservatively estimated as described in reference 1.
Other equipment loads are similarly estimated.
4.4 WIIND LUADS Wind. loads will be 15 lbs/ft 2 for walls up to 29 feet above grade, 20 lbs/ft 2 for walls between 30 and 49 feet above grade and 25 lbs/ft 2 for walls between 50 and 99 feet above.grade.
These loads are in accordance with the FSAR.
2
4.5 LOAD COMBINATIONS The loading combinations that will be considered for the masonry structures are shown in Table 4-1.
These loads and loading combinations are consis tent with the FSAR, with the exception that seismic loads are not considered.
Consistent with the FSAR and reference 2, a one third increase in allowable stress is permitted for wind loads.
5.0 MATERIALS AND ALLOWABLE STRESSES 5.1 MATERIALS Basic materials used in the construction at San Onofre Unit One for masonry walls and their specified minimum design strengths are as follows:
A.
Grout* and Mortar*
2
=
2,000 psi B.
Reinforcing Bars f
= 40,000 psi C.
Mlasonry*<
(Hollow Concrete Grade A Block) f
=
1,350 psi D.
Masonry* (Fully grouted 1,500 psi hollow concrete block)
- In-situ test results may be used in lieu of the values given for f' and f' where appropriate.
c 3
TABLE 4-1 LOAD COMBINATIONS FOR MASONRY STRUCTURES Definitions and Nomenclature for Load Combination D
= Dead Loads or their related internal moments and forces.
L = Applicable live loads or their related internal moments and forces.
T = Thermal effects and loads during normal operating conditions based on the steady state condition.
Ro
=inum pipe and eauioment reactions during normal operating conditions based on the steady-state condition, if not included in the above loads.
W
= Wind loads.
Sm = Alowable load for reinforced masonry using the working stress methods of ACI 531-79.
Load Combinations for Masonry Structures S
=
+L (a)
S
=TD + L +R+T
(
- 1) L+R+
(b) 0 O0 1.33 S D + L + W (a) Where applicable, impact effects of moving loads shall be included with the live load L.
(b) To will not be considered when it can be shown that the load is secondary and self-limiting in nature.
5.2 ALLOWABLE STRESSES The Working Stress Design (WSD) methods in reference 2 will be utilized.
These methods will be employed on the basis of a modular ratio of 22.
The allowable stresses are given in table 5-1.
These allowable stresses are as given in reference 2.
5
Table 5-1 Allowable Stresses in Reinforced Masonry S
Ilowable Maximm Description (psi)
Compressive Axial' 0".22f 1000 Flexural 1200 m
Bearing On ul1 area
.00 On one-third area or less
.375f' 1200 Shear Flexural members.
50 Shear Wails Masonry Takes Shear
!/Vd =0 0
74 A'I/ Vd >5 I 75 Deformed Bars 140 Tension Grade 40 20,000 Grade 60 24,000 Joint Wire
.SF 30,000 y
Comp ros ion 0.4 6
Notes to Table 5-1:
(1) These valuos shall be multiplied by (1 -
(-
)
if the wall has a significant vertical load.
t (2) This stress shall he evaluated using the area determined to be in flexural compression.
(3)
Net bedded area shall be used with these stresses.
(4) For M/Vd values between 0 and 1 intercolation shall be made between the values given for 0 and 1.
7
REFERENCES
- 1.
Bechtel Design Guide C2.7, Seismic Category I Cable Tray and Conduit Raceway Support Systems, Bechtel Corporation.
- 2.
Building Code Requirements for Concrete Masonry Structures (ACI 531-79) and Commentary -
ACI531R-79, American Concrete Institute.
- 3.
SCE letter dated July 17, 1980 to the Director of the Office of Inspection and Enforcement, Region V;
Subject:
Docket No. 50-206, IE Bulletin No. 80-11, Masonry Wall Design, San Onofre Nuclear Generating Station Unit 1.
8