ML20086D556

Rev 6 to General Design Criteria BFN-50-C-7104, Design of Structural Supports

ML20086D556
Person / Time
Site:	Browns Ferry
Issue date:	11/14/1991
From:	Barnett R, Mccarraher P, Rieck P TENNESSEE VALLEY AUTHORITY
To:
Shared Package
ML20086D549	List: ML20086D546 ML20086D556
References
BFN-50-C-7104, NUDOCS 9111260148
Download: ML20086D556 (16)

Text

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, ISSUE DATE. July 1 1%7 , , , _,,

REVISION HO R6 R R R R DATE 7/1/87 g, g,ff PREPARED r A. McCarraher [ #d#b CHECKED p , 3, pg,cg /f%[j REVIEWED J. R. Rupert APPROVED R. o. Barnett [

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e BROWNS FERRY NUCLEAR PLANT DFN-50-C-1104 DESIGN OF STRUCTURAL SUPPORTS TABLE OF CONTENTS e

Page  ;

1.0 ctASS I SEISHIC HVAC DUCT AND DUCT SUPPORT DESIGN 1.1 Pu rp o s e a n d S c o p e . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . I-1 1.2 Background.......... ... ......................... ... 1-1 1

1.3 Du c t Su pp o r t S y s t eni Ana l y s i s . . . . . . . . . . . . . . . . . . . . . . . . . . I-2 l

1.4 Properties of Duct Sections. . . . . . . . . . . ............... I-5 )

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1.5 Du c t S t r e s s e s . . . . . . . . . . . . . . . . ... .......... .. ...... 1-6 1.6 Design Loading Combinations for Ductuork and Supports. I-7 1

i 1.7 Duet Qualification. ............... ................. 1-8 1.8 Support Desi6n. ... ...... . .. .................. I-9 19 References............................................ 1-10 2.0 gjlCJHICAL_qbBLE TRAY AND SUPPORT SYSTEM SEIS}11C DESIGN 2.1 Introduction.......................................... 11-1 2.2 Design Evaluation of Existing Cable Tray System anf Supports.............................................. 11-2 2.3 Design Requirements for New Supports.................. II-2 2.4 Load Combinations and Allowable Stresses............. 11-5 2.5 Seismic Design and Analysis... ....................... II-6 26 Referencee............................................ 11-10 xi PLDNE109--880/2 m- 9Mi\.MPHilhWEr6 UJ

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BROWNS FERRY t/UCLEAR PLANT BFN-50-C-7104 DESICN OF STRUCTURAL SUPPORTS l TABLE OF CONTENTS  ;

Ea3e 3.0 ELECTRICAL CONDUIT AND. SUPPORT SYS1EM SEISMIC DESIGN 3.1 Scope.................................. ...... ....... 111-1 3.2 Defirttions... ........ ............................ . 111-1 3.3 Analytical Basis................ ......... ........... 111-4 3.4 Load Combinations and Allowable Stresses. ............ 111-7 3.5 Design Considerations...... .......................... 111-9 3.6 Additional Considerations for Design of Support Systems................ ..................... III-11 3.7 Alte rnat e Qu a li f ic a t ion Me thod s . . . . . . . . . . . . . . . . . . . . . . 111-11 3.8 References...................... .................... 111-12 List of Figures Figure 3.2-1 Axial Forces.......................... III-2 Figure 3.2-2 Lateral Forces........................ 111-3 List of Tables Table 3.3-1 Dimencions and Weights of Rigid. conduit. III-5 Table 3.3-2 Cable Weights........................... 111-5 Table 3.3-3 Conduit Insulation Weights Thermo-Los 330.......................... III-6 Table 3.4.2-1 Table of Maximum Design Loads and Allowable Stress for Conduit Support Design.................................. Ill-B I

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i PLDNE109--880/3

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TVA 10535 (PELC-6 80 l

BROVWS FERRY NUCLEAR PLANT BFN-50-C-1104 DESIGN OF STRUCTURAL SUPPORTS IABLE OF CONTEMTS Pag 4.0 CONCRETE ANCHORACES 4.1 Scope knd Purpose. . ............. ................... IV-1 )

l 4.2 Background.. ........................................ IV-1 4.3 General Requirements.................................. IV-1 l l

4.4 Evaluatica of Inspection Data for Existing i Concrete Anchoragen................................... IV-1 j 4.5 References.................................... .. .... IV-3 5.0 gxcEPIlpyS V-1 6.0 COKMI]MENTS/REOUIREMENTS VI-1 xiii I

PLDNE109--880/4 TVA 10$35 (PESC449)

BROWNS PERRY WUCLEAR PLANT BFN-50-C-7104 DESIGN OF STRUCTURAL SUPPORTS i

GENERAL l DESIGN CRITERIA NO. ]TN-J0 C-713 E

BROWS f_ERRY RUC1 EAR Pt. ANT IITLE: DES!cN or STRUCTURAL SUPPORlg PLDNB109--880/1 TVA 10135 (PE&C449)

BROWNS FERRY MUCLEAR PLANT BFN-50-C-7104 DESIGN OF STRUCTURAL SUPPORTS l

GEN EPJ1 DESIGN CRITERIA No. BJN-50.-C-7104 BROWNS FERRY NUCLEAR PLANT TITLE: DESIGN OF STRUCTURAL SUPPORI}

Section 1.0 CLASS I SEISM.T.C HVAC DUCT AND DUCT SUPPORT DESIGN I

PLDNE109--860/5 TVA 10$35 (PE&C449)

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l BROWilS FERR1r NUCLEAR PLANT BFN-50-C-1104 DESICW OF STRUCTURAL Supp0RTS .

l 1.0 CLASS'I SEISMIC HVAC DUCT AND DUCT S9pPORT DESICW 1.1 EUROSE AND scope j The purpose of this crit.eria is to provide the requirements for {

i the seirmic cnalysis and qualification of existing and i e ductwork and associated supports for seismic. Class I duct. systems I at Browns Ferry Nuclear plant. This criteria covers rectangular- l and round metal ducts. Two types of Sheat Metal and Air Conditioning Contractors' Wat!onal Association (SMACNA) transverse joint- construction for rectangular ducts, companion. angle and-pocket-lock t> pen, are within the scope of this .riteria.

Additionally, all welded joint constructions are aovered. ,

The criteria requirements for rectangular duct, companion angle  ;

z and pocket lock type construction, are substantially validated by l

seismic testing (Reference 1.9.1 and 1.9.5), performed on duct l l

sections representative of existing HVAC systems at ?FN. 3 k' hen schedule pipe is-used as ductwork, this criteria or BFW-50-C-7103 shall be used for qualificktion of duct. When duct

• is qualifled in accordance with BFN-50-C-7103, criteria BFN-50-C-7101 shall be ust4 for qualification of supports.

1.2 Mc%@c'Qq  :

i Subsequent to the development of an artificial earthquake time -

history, which closely mt.tches the smooth Housner curve, TVA committed to and performed an impact assessment to verify that the duct systems were, as a minimum, in compliance with the interim operability criteria. The performana.e.of this. impact.tssessment ,

,  ! included the use of combining two directim.:1 loads absolutely, as opposed to SRSS methodology with El Centro used during the ,

original requalification effort. The results-of the. evaluation were reviewed and-accepted by the.WRC as documented in Inspection Reports 89-32, 89-42, and letter to 0. D. Kingsley dated August 4

22, 1990.

The impact assessment will be updated and/or other documentation  !

. generated to demonstrate that ductwork previously qualified using the El Centro response spectra and SRSS load combination method '

sneets the long term qualification comitments.

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4 ptDNE109--880/6 TVA 10535 (PEAC449)

BROWNS FERRY N0 CLEAR PLANT DFN- $ 0- C- 1104 DESIGU OF STRUCTURAL SUFPORTS 1.3 DUCT SUPEORT SYSTi(A_Nbl.YSIS Each duet support system consists of a duct run and a series of supports which are spaced at approximately equal spacings when cor.ditions permit. There are three bacic types of supports for the Browns Ferry Nuclear Plant HVAC ductwork. The DW. type typically sustainn deadweight and downward Seismic load. The 2W-type support provides restraint for loadings in the vertical and lateral directions, while the 3W-type support resists the axial load in addition to performing the function of 2W-type support.

1.3.1 6NALYSIS METHODS Analysis of the Seismic Class I ductwork shall be performed by computer aided modal response spectrum dynamic analysis or by using an equivalent static load j

method (i.e., hand calculations).

l 1.3.1.1 Effective mass and stiffness of the duct supports shall be accounted for in the analysi's of the ductwork.

1.3.1.2 Ducts shall be modeled as beams based on the effective bending and shear stiffnesses of their cross-sections. However, as a result of seismic testing (Reference 1 9.1 and 1.9.5) of representative duct sections, it has been determined that actual duct spans respond more flexibly than predicted by an ideal beam equation. Therefore, for rectangular ducts with companion angle and pocket-lock transverse joints, frequency correction factors have been developed (Reference 1.9.10) and shall be applied for more accurate frequency prediction.

This shall be accomplished by multiplyinr, the ef fect ive bending monents of inertia, I , by the square of the frequency correction factor. The frequency correction factors are 0.59 and 0.8T for pocket lock and companion angle constructions, respectively.

For round duct and all welded ductwork, the frequency correction factor of 1.0 chall be used.

The bending moments and chears in duct spans from the analysis shall be used for the calculation of duct stressen basad on the effective section moment of inertiu, I, (without the frequency correction factor), as specified in Subsection 1.4.3. The reactions shall be used as the seismic loads for support evaluation.

1-2 PLDNE109--880/7 TVA 10D$ (PE&C449)

BROVWS FERhY NUCLEAR PLANT BFN-50-C-1104 .

DESIGN OF STRUCTURAL SUPPORT 3 1.3.1.3 Design and evaluation of the ductwork shall be pecforr.ed uains the Housner response spectra from the Master Acceleration Response Spectra (MARE) Report (Reference 1.9.8). The resultant seismic stresson shall be determined by enveloping the strasses from two sets of seismic forces, xy and yz, where y is vertical and x and z are orthogonul horizontal directions. The resultant stresses for each set of sotamic forces shall be obtained by absolute num (ABS) combination of the resultant directional components.

1.3.1.4 The damping ratio of DBE (SSE) response spectra used on each type of the ductwork shall be au follows:

Duetwork_ paghfmF3.go, Rectangular, companion angle or pocket lock 0.01 Rectangular, all welded 0.02 Round duct, all types except schedule pipe 0.02 Schedule pipe 0.01 The damping ratio for rectangular ductwork constructed with ccmpanion angle and pocket lock jointa has been substantiated by seismic testing of representative duct sections (Reference 1.9.1 and 1.9.i). ,

1.3.1.5 Contribution of rigid nodes (ZPA effect) shall be considered by ustr.g the raximum tvtilding accelerations for the applicable flooe as the ZPA values. 20 hertz is considered to be the lower bound of the rigid range.

1.3.1.6 For non-rigid duct system analyzed using the equivalent static load method, a multimodo factor of 1.5 shall be applied to the response spectra acceleration.

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PLDNE109--800/8 l TVA 1052)(PE&C4 89) ,

1 14ROWNS FFPRY NUCl.F.AH PLANT DFN-50-C 7104 DESIGN OF GTRUCTU'tAL SUpl' ORTS

• ' 2 Ufr.C I S .I . CotM i de.ra t i on s The following conditlons require special connideration:

1.1.2.1 Conc ent. rat ed wei ght n alonr, t he duc t. work (e r..,

miscellnneouu attachments such ac condult, t u b i n e, ,

pipinr, or in Iino comronento such as dampers, grilles, filters, fans, heaters, and valven).

1.1.2.2 Cutnote for grillo openings.

1.'+.2.3 t,atnral/avtal nupport placement in the prnximity nf duct bonds and branches and the dist ribut non of loado within t he ductwork and 'turport s in these regiors.

1 3.2.4 All welded heavy gaur,e duct work.

i 1.3.2.5 Trannit ions between rer, inns of rigidly nupport ed ductwerk and flexibly support ed (e.g. all t od i hung) ductwork.

1. 3 . 2 . f> Building exterior ductwork exposed to weather conditions shall be analyzed for these additional weather induced loading condittons.

1 3.2.7 l>lfferentl11 seismic movements shall be a c c omod ated in den (gns of duct systems running hotween buildings.

F.ffects of these conditions nhall be conaldered by employing cormonly accepted techniques for simplified equivntent static analysis or rigorous dynanic analysis (e.g., response spec t rum : nodal ari.ilysis) . In reevaluntten of existing darlr.ns for the above ernditions, consideration should be given to use of rigorors analysis tochtilques to minimize c on5 0rval i Sfhs .

predominant ly rod hu'ig duct syst em may benefit f rom snelysis utilizing ristoring force methodology, and/or other '

analyt Ical met. hods.

g 14 plDNF.109--880/0 T VA 10$3$ (PC&C4H)

BROWNS FERRY NUCLEAR PLANT BFN-50-C-7104 DESIGN OF STBUCTURAL SUPPORTS

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1.4 PROPERTIES OF DUCT SECTIONS 1.4.1 Ma_terial Properties and Wgights Ductwork is fabricated of material as specified on the Bill of Materials drawings. Rectangular ductwork is commonly specified to be constructed in accordance with medium pressure standards of Reference 1.9.6 with ASTM A525, A326, or A527 galvanized steel sheet metal. Round spiral weld pipe duct is commonly specified to meet AS'IM A211 requirements Which, in turn, specify construction with ASTM A570 steel sheet metal. In lieu of other data, mechanical properties of these materiala shall be conservatively taken for design as followe:

ASTM _Desitant;Lon Yield Point. P y Tensile Strengths._Eu~

A525, A526 , A5 2 7 33 kr.L A5 kat

! A211 (A570) 30 ksi 49 ksi Support members, duct stiffeners, and companion angles are typically A36 steal with Fy = 36 ksi and Fu . 58 kai.

Where other materials are specified, the appropriate mechanical properties should be used for design.

1.A.2 Duet Weights Weights of various stro ducts are to be calculated based on SHACNA sheet metal gauges and stiffener requirements assuming the ductwork is fabricated in 4 ft sections. All sheet metal thicknesses are taken for uncoated sheets (e.g., see Reference 1.9.7, page 6 '3). A 25 percent increase shall be applied to the calculated metal weight of the duet (i.e., without insulation) in the final tabulation. Thic is to account for minor additional weights such as galvanizing, slight i variations in matal thickness, additional transverse joints of sections at less than the average 4 ft assumed length, fasteners, and miscellaneous light hardwaro attached to the ductwork. The 25 percent increase is not required if more accurate total weight determination is perf ormed.

Where insulation is present, its weight shall be determined and added to the weight of the duct.

1-5 pLONE109--880/10 SH/usasure/\redTo

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3ROWWS FERRY NUCLEAR PLAN ~ BFN-50-C - M04 DESICW OF STRUCTURAL SUPNRTS -

1.4.3 Effective Duct Section The effective moment of inertia for a rectangular duet shall g be based on the SMACHA approach (Reference 1.9.3) which y considers 2 inchen at the ends of each duct side to form a '

f our-cornered 'oeam section to resist the bending monient on the doet cpan. :2 ,.

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'*" 4 Ouct corner (typ )'

Effective Duct Section, Rectangular Duct The effective moment of inertia about each axis of a rectangular duct is then calculated by Equations (1) and (2):

I t = 8t (D 2/4 + (D/2 -- 1)2] gq (1) 12 " Bt [W /4 + (W/2 - 1)2] Eq (2) where:

11, 12= Effective moments of inertin about axes 1-1 and 2-2 (in.4)

D. W = Depth and width of duct cron-section in 3 itiches. respectivelv t = Sheet metal thickness in inchos For round ducts, the full section shall be used for the bending moment of inertia.

1. 5 pUCT STRESSES The duct utresses shall be calculated for bending moments and shear dua to dead weight and seismic loads.

1-6 PLDNE109--880/11 1

g. TVA 1053$ (PE1C4-49)

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BROWNS FERRY NUCLEAR PLANT' BFNe50 C-7104 DESICP OF STRUCTURAL SUPPORTS The bending stress' equation for the' duct section is:

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• llBG I.

where:

p I = Maximum bending stress (psi)

M = Bending moment of duct span (ft-ib)

I, '= Effective monent of inertis of the duct'section (in.4).  ;,

f = Radius of round duct or half of rectangular duct height with respect to I,(in.)

The shear stress equation for the round duct section is:

T.s =2V/A, where:

Ts a Shear stress at duct section (psi)

V= Shear at duct section (1b)

_ A, = Cross-sectional area of the duct q Shear (V) at the rectangular duct section shall be evaluated by comparisen to the allowable shear cap 6 city (Va ) as described in Section 1.7.- Therefore, calculation of shear stress (-T s) is not

-required.

1.6 DESIGN LOADING CO'iBINATION,S FOR DU_CTWORK'AND SUpponTS In general, ductwork and supports shall only be designed for the following load combination:

I

' Dead Load-+ DBE (SSE) Seismic Loads For ductwork exposed to weather, it may-be necessary to consider additional loads due to weather ef fects such as wind. or tornado depressurization.

Loading combinations shall'be by absolute sum (ABS) combination of the resultant dead load and seismic load' stresses.

I-7 PLDNE109--880/12 l

TVA 1M35 (PEACjpn}______ _ _ _ l

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-E2: BROWNS FERRY NUCLEAR PLANT BFN-50-C-7104 DESIGN OF STRUCTURAL SUPPORTS 1.7 DUCT OUALIFICATION Bending stresses in ductwork for deadweight plus DBE (SSE) seismic load combination shall be limited to the following allowables:

Fb = 12,000 pui for rectangular ducts Fd = 15,000 psi for round dut:a TVA's duct testing (Reference 1.9.1 and 1.9.5) has s6ismically qualified rectangular ducts for at least 6.4 g peak acceleration of simply supported, uniformly loaded single span ducts of maxinum span lengths. Based on test results, the maximum allowable shear force f or daadweight plus DBE (SSE) seirmic load combination for rectangular ducts is:

4 Vu- 5.5 w (6.4) -"

where:

Va= The allowable shear capacity of a rectangular duet cross-section (1b) w = The uniform weight / length (1b/ft) of duct including insulation.

I, = The effective bcnding moment of inertia of the duct cross-section (in 4).

EOTE: le is dependent on the weak axis or strong axis orientation of the duct with respect to the shear load being evaluated. -

For evaluating the shear at a section with an unreinforced opening in a shear web (e.g., at a grille), the allowable shear, V a, shall be reduced in proportion to the ratio of the gross area (i.e., without the opening) to the net area (i.e., with the opening) of the two shear webo.

If all welded heavy gauge duct is used (i.e., heavier than conventional SKACNA construction), as an alternative to comparing to Va computed above, the maximum average shear stress on the gross area of a flat web may be computed not to exceed the allowable shear stress determined in accordance with specifications of the AISI (Reference 1.9.4, Subsection 1.4). If the AISI method is used, the 1/3 increase allowed by AISI for seismic loads shall be applied to the allowable r shear stress for the DBE (SSE) seismic load combination.

Round ducts shall be evaluated for an allowable shear stress not to exceed 0.53 F (i.e., 0.40 Fy increased by 1/3 for the DBE (SSE)

< seismic loads .

L Duct stress shall not exceed 90 percent critical buckling for axial compression for deadweight plus DBE (SSE) seismic load combination.

1 1-8 TVA Ris9@Mt.66SO/13

t BRO'.'N'3 FERRY NUCLEAR PLANT BFN-50-C-7104 DESIGN OF STRUCTURAL SUPPORTS 1.8 SUFPORT DESIGN All supports shall be designed to take the deadweight and seismic loads resulting from the duct analysis.

1.8.1 Allowable Stresses for Supports Allowable stresses for seismic DBE (SSE) events in combination with other loads, for structural steel, connection bolts, and welds shall be as specified in the AISC Manual (Reference 1.9.7) increased by 1.5 for seismic loads. However, in no case =FA.11 allowables after the increase exceed 90 percent of the spestfied minimum yield stress for steel for tension and bending, 90 percent of critical buckling for axial compression, or 0.9 F y /N f3 for shear, including shear on base metal for welded connections.

The design of anchorages for new or modified supports shall meet the design requirements of Reference 1.9.11. Minimum edge distance for baseplate holes for new or modified supports shall be in accordance with AISC Specification (Reference 1.9.7). Evaluation and acceptance of existing anchorages for loading combination including seisule load shall be in accordance with Generic Implementation Procedure (G1P) for Seismic Verification of Nuclear Plant Iquipment (Reference 1.9.9), Appendix C, Revision 2, corrected June 28, 1991, or later revision if applicable.

All pref abricated commercial items may use the approved manufacturer's rocommended allowable load. -

Design of skewed fillet welds shall be in accordance with the requirements and procedures as described in Section 4.8 of Reference 1.9.2.

1-9 PLDNE109--880/14 I

TVA 10$35 (PC&C44h

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. BROWNS-FERRY NUCLEAR PLANT. BFN-50-C-1104 DESICW OF STRUCTURAL SUPPORTS

1.9 REFERENCES

-1.9.1_ TVA-C"" 79-7, " Test Report on Seismic '

Quall . tion / Verification of HVAC Ducts", Volume I, Table 1. _ _

1.9.2 TVA Civil Dasign Culde,- DG-C1.6.4 Design of Structural Connections (Bel 880622 009).

1.9.3 SMACNA, Rectangular Industrial Duct Construction Standards, 1980, Section 9.

1.9.4= Specification of the AISI Cold-Formed Steel Design Manual, 1983 Edition.

1.9.5- TVA Report MA2-79-1; " Summary Report for HVAC Ducts Seismic Qualification and Verification /Improvenent Program", .

Mechanical Analysis, Section 2.

1.9.6 SMACNA High Velocity Duct Constructior, Standards, Second E

Edition - 1969.

1,9.7 AISC, Manual of Steel Construction, 8th Edition.

1.9.8 TVA CEB 88-05-C R1. Browns Ferry Nuclear Plant Master .

Acceleration Response Spectra.(MARS) Report for Seismic Class 1 Structures (B41 900112 004) 1.9.9 Ceneric Implementation Procedura (CIP) for Seismic Verification of Nuclear Pier.t Equipment.

1.9.10 Design calculation Nuaber CD-Q0000-883360, " Backup Calculation for-BFN-50-C-7104", RIMS number b22 880525 126.

1.9.11 Civil Design Standard DS-C1.7.1, General Anchorage to Concrete

!- I-10 i PLONE109--880/15

, ,.,-_ . _ ., _TV A_10535 (P ES C4-49J

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