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REGUI ATO INFORMATION DISTRIBUTION TEM (RIDS)

ACCESSION NBR;8402140419 DOO,DATE: 84/02/10 NOTARIZED;. NO DOCKET ¹FACIL:50 275 Diablo Canyon Nuclear 'Power Plant=i Uni,t ii Pacific Ga 05000275

AUTH,NAME AUTHOR AFFILIATION „SCHUYLER~J ~ 0. Pacific Gas' -Electric Co.

RECIP NAME RECIPIENT AFFILIATIONKNIGHTONrG ~ N ~ Licensing Branch >3

SUBJECT: Forwards= info re turbine bldg roof truss modeling istudiesgper SSER 20 Open Item 11.Study validates =use of generalizeduniaxial members „to-obtain individual truss member-responses.

DISTRIBUTI N CODE: 8001S COPIES RECEIVEDILTR .~'NCL J SIZE;TITLE: Licensing Submittal: PSAR/FSAR Amdts 8, Related Correipondence.

NOTES:J Hanchett icy PDR Documents'5000275RECIPIENT

IO CODE/NAMENRR/DL'/ADLNRA L83 LA

INTERNAL: ELD/HDS2IE/DEPER/EPB 36IE/DQASIP/QA821NRR/DE/CEB iiNRR/DE/EQB 13NRA/DE/MEB 18NRR/DE/SAB '24NRR/DHFS/HFEBOO,NRR/DHFS/PSRBNRR/DSI /AK8 26NRR/DSI/CPB 10.NRR/DSI/ICSB 16NRR/DSI/PSB 19NRR/DSI/RSB 23RGNS

EXTERNAL ACRS 61DMB/DSS (AMDTS)LPDR 03NSIC '5

NOTES:

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PA.CIPIC CvA S A.ND ELECTRIC COMPS.NT77 BEALE STREET ~ SAN,FRANCISCO, CALIFORNIA 94106 ~ (415) 781.4211 ~ TWX 910.372 6587

J. O. SCMVYLBRVICC CRCCIOCNZ

RIICCCAR ROWCR OCRCRAYIOR

February 10, 1984

PGandE Letter No.: DCL-84-052

Mr. George W. Knighton, ChiefLicensing Branch No. 3Division of LicensingOffice of Nuc1ear Reactor Regu1ationU. S. Nuc1ear Regu1atory CommissionWashington, D. C. 20555

Re: Docket No. 50-275, OL-DPR-76DiabIo Canyon Unit 1

SSER 20 Open Item 11

Turbine Bui 1ding Roof Truss Mode1ing

Dear Mr. Knighton:

The enc1osed materia1 responds to your request for confirmatory documentationon Open Item 11 in Safety Eva1uation Report, Supp1ement No. 20. This studydocuments the va1idity of using genera1ized uniaxia1 members to obtainindividua1 truss member responses for the turbine bui1ding roof truss. Thissubmitta1 comp1etes PGandE action on this issue.

KindIy acknow1edge receipt of this materia1 on the enc1osed copy of this1etter and return it in the enc1osed addressed enve'lope.

Sincere1y,

Enc1osure4

cc: D. G. EisenhutH. E. Schier1ingService List

J .. chuy1er~ ~

:. CI4ORC4O4<9. CI4O»O ';: I !::,';~'-'- ' PDR;„ADOCK 05000275'' ';,",, .~'I

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PGandE Letter: DCL-84-052

ENCLOSURE

TURBINE BUILDING ROOF TRUSS MODELING

Additional studies have been completed which further substantiate the validityof using the two generalized uniaxial members to obtain individual trussmember responses for the turbine building roof truss.

The roof truss has been modeled by equivalent members to reduce the size ofthe turbine building horizontal model. The roof truss is modeled by twogeneralized uniaxial members, each represented by a 6x6 stiffness matrix.This reduced stiffness matrix is directly added to the overall stiffnessmatrix of the structure at the appropriate locations.

Figure I shows the actual building roof truss model and the equivalentgeneralized element model used in the analysis. The figure also shows thedegrees of freedom (DOF) considered in developing the equivalent model. The6x6 stiffness matrix of the roof truss member can be developed through the useof symmetry from the six DOFs shown on Figure I. The matrix is calculated bysuccessively applying a unit displacement in the direction of each DOF and bycalculating the associated forces with the other five DOFs restrained. Theeast-west mass of the roof truss is lumped at the three nodes of theequivalent generalized element model by tributary height. One half of thetruss mass from elevation 193'o 201.85's lumped at each of the east andthe west nodes. The mass of the trusses above elevation 20'1.85's assignedto the center node. The equivalent roof truss model reproduces with areasonable degree of accuracy the static and dynamic behavior of the actualtruss. In particular, the horizontal deflection at the top of the columns andat the center of the roof for lateral loads applied at the top of both columnsare within I percent of those obtained from the actual system as shown inTable 1. A similar degree of accuracy exists for static deflections undervertical loads applied at the roof ridge as presented in Table 2.

The following procedure has been adopted to obtain the seismic forces in theindividual truss members for evaluation purposes. The global displacements(hX, AZ, 8y) are obtained at the east and west end nodes of the equivalentroof truss model from a response spectrum analysis of the turbine buildinghorizontal model. The maximum accelerations are also obtained at the two endnodes and the center node. A local detailed model of the roof truss is alsodeveloped. A static analysis of this mode'I is performed, applying the global4(, bZ, Sy displacements as prescribed end displacements to this model. Astatic force is also applied simultaneously at each node, equal to the mass atthe node multiplied by the enveloped maximum acceleration obtained from theglobal analysis. The forces in members obtained from this static analysis areused for member evaluation. Since both the boundary displacements, as well asthe local inertial effects, are included in the static analysis in aconservative manner, the forces determined in the members are conservative forevaluation purposes.

0194d

To demonstrate further that the above procedure of cascade analysis issatisfactory and adequate for determining the member forces, the followingstudy was conducted.

A model (Model A) of a typical bent of the turbine building superstructurewith the actual roof truss, as shown in Figure 2, was developed. The columnswere assumed fixed at elevation 140's the reinforced concrete portion belowelevation 140's very rigid compared to the flexible steel superstructure. A

response spectrum analysis of this mode'I was conducted with the east-westfloor response spectrum at elevation I40's the input motion and the seismicforces in the truss members were determined.

The same bent was then modeled (Model B) with the equivalent roof trussmembers as shown in Figure 3. This model was subjected to the same input asModel A and a response spectrum analysis was done to 'obtain the displacementsand rotations at nodes 4 and 6 and enveloped maximum accelerations at nodes 4,5, and 6. These end displacements were applied as specified displacements atnodes I and 11 of the local truss Model C (Figure 4). In this analysis theinertial forces were also included by applying the noda'I forces equal to themass at the node times the maximum acceleration (of nodes 4, 5, and 6)obtained from analysis of Model B. These static forces were applied in a

direction consistent with the fundamental horizontal mode of the Model A since88K of the total weight is mobilized in this mode.

The above procedure is the same method used in the horizontal building modelto get individual truss member forces. Table 3 compares the importantfrequencies and participation factors between the actual roof truss-bent ModelA and the equivalent roof truss-bent Model B. The comparison is very close,indicating that the dynamic properties of the roof truss are successfullyretained by the equivalent model.

Figures 5 and 6 show that the axial forces and moments in individual trussmembers obtained by the cascade analysis are in excellent agreement with theactual model forces and moments. The cascade approach produces conservativeforces compared to the results from Model A except for a few locations. Thesefew locations, however, do not control the member design.

It is concluded that equivalent truss adequately models the dynamic responseof the actual truss and the cascade analysis used in computing the seismicforces for horizontal motion in the turbine building roof truss members issatisfactory for member evaluation purposes.

0194d-2-

Table 1

COMPARISON OF NODAL DISPLACEMENT(, DUE TO

HORIZONTAL LOADING ~ 1000

Location D.O.F.*Actual RoofTruss Model

Equivalent RoofTruss Model

East End

OY

22.219

0.031

0.0281

22.272

0.031

0.0283

Center

AX

eY

23.386

.000

—.0005

23.473

.000

—.0003

West End

AX 22.219

-0.031

22.272

-0.031

OY 0.0281 0.0283

* NOTE: AX Horizontal Displacement, inchesAZ = Vertical Displacement, incheseY ~ Rotation in X-Z Plane, radians

EAST WEST

T1002906-DIS

Table 2

COMPARISON OF NODAL DISPLACEME(TS, DUE TO

VERTICAL LOAD ~ 1000

Location D.O.F.*Actual RoofTruss Model

Equivalent RoofTruss Model

East End

AX 27.966

0.101

28.012

0.101

eY 0.0032 0.0032

Center

eY

0.000

138.19

0.0000

0.000

138.41

0.0000

West End

AX

eY

-27.966

0. 101

-0.0032

-28.012

0.101

-0.0032

* NOTE: AX = Horizontal Displacement, inchesAZ Vertical Displacement, inches

I eY Rotation in X-Z Plane, radians

oooo"

EAST WEST

T1002906-DIS

Table 3

COMPARISON OF DYNAMIC PROPERTIES OF ACTUALTRUSS-BENT AND EQUIVALENT TRUSS-BENT MODELS

Mode No. Freq. (Hz.) Part. FactorsX Effective Wgt.

(Cumulative)

ActualRoofModel

1.74

7.87

11.27

0.65

0.01

0.19

88.6

88.6

96.1

quivalentModel

1.72

7.93

10.95

0.65

0.01

88.5

88.6

95.8

T1002906-DIS

EL.

193'CTUAL

ROOF TRUSS MODEL EL.

140'AST

WEST

EL. 210 8"4

EL.

193'IGID

ELEMENT

EL.

140'QUIVALENT

GENERALIZEDMEMBER MODEL

Figure 1

TURBINE BUILDINGHORIZONTALMODEL

ROOF TRUSS

h

1314

1516

1718

19

2021

A

12

910

22

2326

2427

EL. 140'5I

28

0

ALLBEAM ELEMENTS

Figure 2

ACTUALROOF TRUSS BENT MODEL (MODEL A)

EL. 210.69'

E L.

193'L.

179.5'3Q

Q

EL. 159'1QE

EL. 140'BEAM ELEMENT

SUPERELEMENT

Figure 3

EQUIVALENTROOF TRUSS BENT MODEL (MODEL B)

1819

2021

22

910

Figure 4

ACTUALROOF TRUSS MODEL (MODEL C)

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(b) CASCADE ANALYSISWITH MODELS B AND C

Figure 5COMPARISON OF AXIALFORCES (KIPS)

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40.

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124

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Op

28340

51849,

95. 15. 15.6g

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12'50

29260.

598

C)

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Ggg

(b) CASCADE ANALYSISWITH MODEL B AND C

Figure 6COMPARISON OF BENDING MOMENTS (KIPS- IN)

P

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