ML20150F308

Summary Rept for HVAC Ducts Seismic Qualification & Verification/Improvement Program

ML20150F308
Person / Time
Site:	Browns Ferry
Issue date:	06/16/1979
From:	Neely B, Warrix L TENNESSEE VALLEY AUTHORITY
To:
Shared Package
ML18033A273	List: ML20150F308
References
MA2-79-1, NUDOCS 8807180228
Download: ML20150F308 (44)

Text

En /on,.,

'l

,i TENNESSEE VALLEY AUTHORITY j

i DIVISION OF ENGINEERING DESIGN i

civil ENGINEERING BRANCH

SUMMARY

REPORT FOR l

HVAC DUCTS SEISMIC QUALIFICATION AND j

VERIFICATION / IMPROVEMENT 5 i:OGRAM

((

'I s.

Y'

\\\\

l'

=

'U4 D

h N

l si a

s

]

- f, *

-l Ng'

//

+

.__-/

t y =W 1

y

^~. 1 I

I t,7 I

I

}

1l MECHANICAL AN ALYSIS SECTION NO.2 1

REPORT MA2-791 JUN E 16,1979

$E $D$$! $$o!

o

(

TENNESSEE VALLEY AUTHORITY DIVISION OF ENGINEERING DESIGN CIVIL ENGINEERING BRANCH

-s...g..,-

y.,, n h -gO1N 1110LLBu y

COPY bcr..u o.

'l

SUMMARY

REPORT FOR l

HVAC DUCTS SEISMIC QUALIFICATION AND VERIFICATION / IMPROVEMENT PROGRAM MA2-79-1 June 16, 1979 1

.-r l

1 I

I I

I L F(f)

~

u Mechanical Analysis Section No. 2

/LA '79 _ _

B. B. Neely E

sPfu

^

L. Warrix I

c-t

(

k FOP.EWORD This report includes a brief synopsis of the test require =ents, test results, and actions taken and reco=mendations made as a result of thfs test program. The co plete results of the test program are given in Volumes I, II, and III of CE3-79-7, "Test F.eport on Seis=ic Qualification /VerificationofhTACDucts."

1 1

i

,5 l1 8

.- (

r 1..

I

(

8 s

TABLE OF CONTENTS.

Paragraph Title Page No.

1.0 INTRODUCTION

I 2.0 INDUSTRT APPROACHES I

g I

2.1 General.

1 2

2.2 TVA's Initial Approach 3.0 TVA HVAC QUALIFICATION AND VERIFICATION / IMPROVEMENT PROGRAM.

2 3.1 Phase I.

2 3.2 Phase II 2

3.3 Phase III.

3

~4.0 TEST PROGRAM.

3 3

4.1 Test Specimens 4.2 Test F,ixture 3

4.3 Variable Support.

8 1

4.4 Test Machine 8

4.5 Instrumentation.

8 4.6 Test Wavefonn.

8 4.7 Test Setup 14 4.8 Test Procedure 14 5.0 RESULTS OF TESTS.

14 5.1 Companion Angle Construction 20 5.2 Pocket Lock Construction 20 6.0 COMPARISON OF TEST RESULTS WITH TEST OBJECTIW.S 26 l

6.1 Phase II, Test Objective A 26 6.2 Phase II, Test Objective B 27 6.3 Phase II, Test Objective C 33 7.0 POINT OF INTEREST...................

36 8.0 ACTIONS BEING TAKEN AS A RESULT OF TESTING 37 i

9.0 RECOMMENDATIONS 37 lj 10.0 SUMMiRT 38 1

I t

ii 1

k..

LIST OF TABLES

.(

Page No.

Table Title 6

I.

Types of Construction and Duct Sizes Tested.

28 II.

Stress Data for Upper Bound Runs.

23 III.

Margin of Safety and Safety Jactor for Ducts Tested to Failure..

35 IV.

Sumary of Damping Measurements.

I 1

1

)

I.

.I lX i

a f

k E

'I lii bl LJ n

,,--,w, s-

--e-9 o-T w

1 LIST OF FIGURES Figure Title Page 1.

Test Specimen in Test Fixture

..[......

4 5

2.

Flow Diagram for Duct Tests.

7 3.

Test Fixture and Variable Support 9

4.

Dynamic Calibration of Variable Support.

10 5.

Calibration Curves for Variable Support 1

11 6.

Test Machine Capabilities.

12 7.

Typical Accelerometer Installation.

13 8.

Typical LVDT Installation.

15 9.

Required Response Spectra for 7-percent Damping.

16 10.

Typical Test Setup.

11.

Representative Enveloping of Required Response Spectra.

17 j

12.

Untuned Acceleration Response at Center of Duct Span.

18 5

13.

Tuned Acceleration Response at Center of Duct Span.

19 21 14.

Damage After Run 30.

22 15.

Damage After Run 32.

23 16.

Damage Af ter Run 40.

24 17.

Specimen 1 at Completion of Run 44.

18.

View Inside Specimen 1 at Completion of Test Run 44.

25 19.

Measured and Calculated Duct Skin Stresses (Companion Angle)..

29 20.

Measured and Calculated Duct Skin Stresses (Pocket Lock).

30 31 21.

Variable Support Deflection / Force 1

1 I

I c

8 c

I f

7 h

R f

iv E

1 1.0 Introduction A great deal of uncertainty has long existed as to the seismic with-standability of HVAC ducts designed and supported in accordance with the Sheet Metal and Air Conditioning Contractors National Association (SMACNA) standards.

The SMACNA standards have historically been recog-g nized as an acceptable design approach for ducts in commercial end indus-3 trial applications where dead load and operational loads were the only concern. '1he amount of conservatism inherent in these standards, both in the duct design and in the spacing of the supports, is not known:

neither is it of particular importance for the commercial and industrial applications.

This is especially true for the supports since the number

'g of simple deadweight hangers, composed mostly of standard, readily avail-s able and compartively inexpensive components, may,be greatly increased or decreased in number with little effect on the overall cost.

The situation changes drastically, however, for HVAC ducts used in nuclear power plants. Some ducts are required to remain intact and func-tional during design basis earthquakes and continue uninterrupted j

delivery of cooling air to safety related components and equipment until 3

plant cold shutdown is achieved and fuel is removed from the reactor.

For this condition, questions are raised as to the type of duct construc-tion, support spacing, and support design to be used. The primary ques-

,e E

tion is, are the same duct and support systems defined in SMACNA and devised for commercial and industrial applications capable of performing this duty?

e

.L 2.0 INDUSTRY APPROACHES 2.1 General Many different approaches are being used in the industry.

Some use SMACNA duct construction while others have gone to completely new duct design, with test programs to seismically qualify the new design.

Some utilities and architectural or engineering firms space the duct supports to provide a duct natural frequency (duct con-I sidered as a beam) sufficiently higher than the building reasonance such that the duct will not amplify the building motion. An exten-sion to this rigid duct concept may be the implementation of defined stiffness for the supports,'wherein supports. are designed to deflec-tion requirements instead of stress limits.

j Still others may use support spacings based upon SMACNA recommend-E ations or some other rationale and not consider stiffness of the duct / support system.

In this case, both the duct and supports should be designed to stress limits and system stif fness may be

s..

I ignored. This method necessitates using peak loads from the seismic response spectra since the uncontrolled system frequency may come into coincidence with the principle forcing frequencies of the earthquake. The numbers of possible approaches are many, as are the B

problems and questions associated with each approach.

el 8

SP506

.~

i

4g

\\

2.2 TVA's Initial Approach Because of a desire to use the SMACNA standards, with the option of using either the pocket-lock or the companion angle construction, TVA initially designed bo.th the duct span and seismic restraints to stiffness limits.

This approach resulted from an expediency decision not to develop a new standard for duct construction and a concern for the fragility level of the ducts, whose design by E

SMACNA included n consideration for dynamic loading.

This approach 3

produced, what was felt to be too much conservatism with respect to the size of seismic restraints required.

I 3.0 TVA HVAC QUALIFICATION AND VERIFICATION / IMPROVEMENT PROGRAM g

In response to the concern for excess conservatism, CEB established as a a

specific management objective the task of developing a mort-economical duct / support system and improve the confidence level of the analytical methods and technicues which will assure safety and reliability of the

' system.

To accomplish this goal, the task was planned in three phases as follows:

3.1 Phase I Assuming SMACNA standard duct designs and using the peak of the

q seismic response spectra for lead dete rmina tion, develop a method

E for determinias seismic restraint / support spacing and loads for re-straints designed to allowable stress limits without regard to restraint deflection and spring rate.

This task was completed and issued as TVA Mechanical Design Guide DG-M13.1.1, Heating, Venti-lating, and Air-Conditioning Seismic Qualification of Round and Rectangular Duct Systems, in May 1978.

3.2 Phase II Develop and conduct a full-scale HVAC duct seismic simulation test program to:

A.

Demonstrate that the duct types presently utilized in nuclear 1

power plant design, and which are constructed in accordance with the SMACNA standards possess adequate dynamic load resistance capability such that they may be considered as load-carrying structures whose perfo rmance is predictable by, I

con /entional analytical techniques.

B.

To establish the margin of safety in the seismic qualifica-tion method described in TVA Design Guide DG-M13.1.l.

C.

Provide data which will allow as much balancing as possible between economy of design and safety considerations.

(

Phase II A, B, and C represent th'e objectives of the.est program.

a I

. I t

-,m.mr2 j

s I.

~ ~ ~

3.3 Phase III Develop a catalog of HVAC duct pre-designed support "typicals" to I

represent as many frequently reoccurring support' conditions as feasible.

This effort is just getting underway and is expected to be complete during 1980.

The remainder of this report will be devoted primarily to:

A.

A brief description of the tett program.

E B.

A summarizing discussion of the test results.

C.

A comparison of test results with the test objectives.

D.

Recommendations for further testing.

E.

A brief summary statement.

4.0 TEST PROGRAM 4

TVA Test Plan For HVAC Qualification And Verification / Improvement Program, N-101977, provides a detailed description of the test specimens, test requirements and other relevant information.

Figure 1 shows one test specimen mounted in the universal test fixture and other relevant information. Other specimens were mounted in a similar manner.

Figure 2 is a flow diagram which shows the planned sequence of testing.

There a7 were some minor variations in the planned sequence due to decisions j

which had to be made during the course of the testing.

4.1 Test Specimens Table I shows the dimensions and span lengths of the specimens tested.

As shown, full-size rectangular HVAC ducts of three sizes (both pocket-lock and companion angle construction) were tested in each axis.

Since the span length is unique to the axis tested, this scheme provided data for the equivalent of six duct sizes for i

each type of construction tested.

~

4.2 Test Fixture Ef In actual use, duct systems can be supported in an almost unlimited number of ways.

It was therefore not possible to design a test t_he support method.

Hereinafter, "support" h

fixture to simulate I

shall imply "seismic restraint" unless specifically stated otherwise.

d_ L, i

The as-designed test fixture, Figure 3,

is universal in that it i

o accommodated all specimens tested, in each axis, and for both types

~ ' "

EQ of construction.

The fixture was relatively lightweight and 0

i designed to minimize its effect upon specimen response while, at

! d the same time, being generally representative of anticipated support masses and support methods.

l r NI,

i me,

7s na hrd "4

A Fa tse ta a

N,

r. -

8

=

8

[

. dI_

a N

m i

r

_]

l-l-

.r-(

I p

1 1

S

~

~

z l

l l

~

fu s

N a

n E

r r

M a

r I

C d

,w x

a i.

E s

S

=

P

^

e d

l w

T

,.,s

~

'O u

_a d

ES

.e

.,a

~

s s

e T

/ -

D

/

N N

s_

A S

s,

.r E'

I E

R I

UT F

X I

T l

i S

sE T I

s-E R

U G

0 f

I F

L m

, j

~

r r

e a

r g

t m

A i

r

,=

Pe u

p a

t e

w J

g l

r 34 o.

f a

r

. 7 e

-o w

u r

• a

' a-

~

l l

I e

" ^ *a s

I r

~

l-.

I 7

l f

7

<":4

]r

- y 1

g 7

1 Il g_g..

Ep ii g _. -

~

eve l

~

n VIBRATION TESTING OF HVAC DUCT DUCT CONSTRUCTION TYPE LEGEPD KKJfET tOCK Cf*8 PAN 10N ANrA[

SUCCESS PATH 68 s de 18 a es TT ST II ' 38 SP1C3 ME N 24 s 60 24a 60

...,, p FAILED PATH IO ' #8

'O ' 48 BACWP 24 s 36 24 a 36 N

24. 60 24a 60

@PGES.S futanMD 2.J

] set = L sin.se pr5T.LL

+

ON S.CatJP.Cf ME NT OLE T S STR.se t,aGg3 y

Ot fu Pt SE C I K-5 N wteGM EL

.ftWett SPTCa-m$ OF Sj$,LECW IE SY j

F

~=,~,'~c'-

_p'

.m <-,-

__p

, ;=,

_g,J,/,='J",,

S 4

m,=,.

..mC I ed1. Se5aA.f RMI ND t.IA#si apg (pg o,[gjy u

n.,.>..

,u n..

.u

.o.,...

.,G..

..,,,,,,,,,Go,,,

m,,,

m c...

~

tem 4 R CM055dCleUNAL set t Str, *08tTS. TO 70.et.Te n sest.

=,r, ;<

LD&f 45 10 SE R$f,uTLst

.is t

.u nono

.o.,.~ _,

,.,...n.

., s,- i.

.,o

,.,,m.

.,u,,,,

, <,. - ~.

.o

-3 l MPLAf 6 T> ens G l

^

S S

s --

->w -..- ->

cm e ->

aci,-,

su,.,..

qj,*,, a" a y,';5;,"

o r, mn.

.,o

.3P8061M.& L Glf.t(1rtpdB

• tt.If8MDWe0CT, mes

.tDe OrcuitsfMT

.tDW tf WL 3,NE

• TUtst TO HF30fe.80CE

. TOW [fVEL 1sef SwitP 10 t,

SwfEP

.F.,FWIOsm ItLV

.g, 10 et ter tirrt e. e o TD (init u t.fiose

,,qng,y. ppog g. pgs gy e.neenDfig gsq7 STEP 4 3 10 948 j

i i.. _ - -, i i.

._., i i.. _ _ i.... i i

_U i

t f

! l = '=uac l

j ai,cin =,o,e t

I t

y m, = i. o., -

...pl,.

-Co.,

l.. >l.

o, m.,

l s

_J M PL.(,

itST ReertiTI g

4...':'.""'.".'.".'.!... a= rg, =y,<= isi

.o

, is r....

r==nva.amo

.,,,,,,,,,,C, U. t t

i

,..Giuty GData1KED i

.t i

I e J =,t =<

eu FIGURE 2

"L"'J""U ff.f.

4 '" a' "$'

l a-FLOW DIAGRAM FOR DUCT TESTING

n. Cave arv 9

- "e'Mirro"mTS

'a"='"

(W

• DefLL OR SsNE GE.T

a

~~

TABLE I TYPES OF CONSTRUCTION AND DUCT SIZES TESTED i

f Type Duct Span Construction Duct Size Skin Thickness Length Length Corepanion Angle 60" x 24" 20 ga. (0.0359")

31.3' 28' 24" x 60" 20 ga. (0.0359")

23.5' 16' 48" x 18" 22 ga. (0. 029 9'")

27.5' 26' 18" x 48" 22 ga. (0.0299")

19.5' 14' 36" x 24" 22 ga. (0.0299")

23.5' 22' 24" x 36" 22 ga. (0.0299")

23.5' 16' Pocket Lock 60" x 24" 20 ga, (0.0359")

31.3' 28' 24" x 60" 20 ga. (0.0359")

23.5' 16'

[

48" x 18" 22 ga. (0.0299")

27.5' 26' 18" x 48" 22 ga. (0.0299")

19.5' 14' 36" x 14" 22 ga. (0.0299")

23.5' 22' 1

24" x 36" 22 ga. (0.0299")

19.5 16' 1

I 1

1

I lI lI

. s I t V

(DUCT TEST SPECIMEN n n n

n,

__A_JL_

~

(

l__

\\/

E E

O O

-l c

\\.

C

D 9

N c

VARIABLE SUPPORT kJ L

f'~1 E--

- N}

5 MOUNTING BEAM S

\\

l i

==

(

7 f t.

28 ft.

f r

FIGURE 3 TEST TABLE TEST FIXTURE AND VARIABLE SUPPORT FOR i

SEISMIC QUALIFICATION OF HVAC DUCTS

8 I

a.

1

~ ' -

I.

4.3 Variable Suppo'rt Since, one goal in this program was to remove all const raints on support system f icx ibili t'y, the natural frequency of the cluct/

support system had to be made to match the predominate frequency range of the seismic response spectra. For the statistically small number of tests conducted, this matching could not be left to chance.

A variable support was designed to alter the structural response of the duct / support system.

The variable supports, one at each of the four support points were specifically designed and fabricated leaf springs made of alloy steel and hardened to a minimum yield strength of 130 KSl.

They were designed to sustain the maximum dynamic load from the heaviest duct at resonance without overstress of the spring.

By altering the mounting position on the spring, I

both the heaviest and the lightest weight ducts could be tuned to first mode resonance of 8 to 11 Hertz, the predominate frequency a

range of the seismic response, spectra.

The variable support, Figure 4, was calib ra ted, both statically and dynamically, for each mounting position on the flat spring.

(See also Figure 8.)

The calibration data was plotted as force versus displacement for each position.

Since spring displacement was recorded continuously during all dynamic tests, the force calibration data allowed a method of determining reaction forces.

The spring calibration curves are shown in Figure 5.

4.4 Test Machine The machine which was used for this testing was a servo-hydraulic high force simulator with 160,000 force-pound capability and up to 500 Hertz maximum frequency response. The mounting surface was flat E

in the horizontal plane and measured approximately 17' x 11'.

The plot in figure 6 shows the capabilities of the machine.

4.5 Instrumentation In addition to the machine mounted control instrumentation, strain and accelerometers were mounted on the duct specimens.

Fig-g gages1 shows the typical location of the acc'elerometers, the general E.]

ure location of the strain gages, and the location of displacement transducers (LVDT'S).

The exact loca ion of the strain gages were sometimes varied, depending upon the specimen and the information desired.

Figures 7 and 8 show typical accelerometer and IVDT installations, respectively.

4.6 Test Waveform 4.6.1 Sine Sweep - Low level sine sweeps from one to 40 Hertz were run to determine the fundamental frequency of the duct with the fixture hard-mounted (not on the variable section of the t

supports) to the test machine.

-*~

'i

[

=

'l ~

) l,/

l

....... %e

4..e 7 ee r

y c %. pIL e

a 4.

.J.

1 g,,,-,, - - N p1

.,3 3' t' p

s

.q

.. ~ - -

Il

,1

's s'ef f

1 1

1

__,t,-

,P

• • =___

6.,z _ _ g r.. a r-fu q

e \\

I g){b ' g

.' l..',

s R;h Q af ji,m aym.e,_

. d....

l1

. A s.y i,

we c,e; NG@Erpl$gs. d pag Ezrb4N

'l

!!$$.M$i l

I h.%

I"U h.

g..g * **

.c..e,-..

.,,,,. 2 g.!;-

%%%Wa',emaan~ m' I

DYNAMIC CALIERATION T VARIABLE SUFFORT FIGURE 4 1.

\\.

9 1

)

LOAD POSITIONS j

l0987654321

(

v v <ru y,r 9 y uv

,f k

itstritt SPRING SUPPORT j

CALIBRATION CURVES FOR VARIABLE SUPPORTS E

10 -H,9 : i 1,8 i

i 5000 7,l '

.,'7 E

---4 i

i si g

lll z'

E

-L_._.I

. i i

2 5

l;'\\\\l l

AQR

• r i f If f

't I.

. Fi I i I

l E

i 4000 m

M,I4/M,!I II iJ4 f

i,.,

I, f

O I

li i I

1

.I J i f i 2

I! F FI

/

1. I 4 I1 I iI i I

I i

I iI I

I t

i =r

__ L) If.

Iii II fi f

iO r 1 11 If!

'1 fr t f

r F1 !

g gpy J f; 1

• ir Ei f f '

J i

f

• i wvvv e IiJ I-1 #

t !I i

i #

i

<3 O

~~~ T If J l i Ii

! I 16 i

6 #.

I I 8-

~~~

g

~~

J.

1 i

f i i I l J

1. r i

A>

19~I.

I

< Ii i if!

J f.

4 f?

1

~I: I B

1 I. i f

f f

a f I f l

dif I+

!I

! i /

/i 2

i

! i F

II I

J

. 'I 1

t 2

if i

, ;A' Y

Q

~~'JiE

D U-iI n~I i

f fI i

f1

]

1. 3. A A A tIJ di

>I

'I 3/

3 #

I i I!

t

/I t I

! i

'EI EI F' !

C. V V V

'7 J

! >I'

• I i, :I i

'#I

' (

4 1

[di E; f

I f /i 1 1 1 i #

2 1

TilI J

.if i I

./ f I

/

i '#

y i

I if 11 f-

'I6 7 ie i fn g

]_

y gi

.I

1. i If i s's 1 If I

7

• s i si >r i

n! i/

i f

i m-f 4 I/

. /i i 3 f" l

~

~ jff fi /

/! ! ~f! I Uf{

MP i

~

',g f II If !

/! l/i :#

iWP~

i

~

tvvv

~

r I di I! I f;fi#

f s

i l ppm ~

1

~

rf:

.!I ifi '# i #

}

~

'l c

I I's

.f * / /

-l p,f l f i f2 A f 7

I

~

iii j

0.25 0.50 0.75 1.00 1.25 l'

DISPLACEMENT (INCHES) -

SINGLE AMPLITUDE - 10 HE m

ig FIGURE 5

-lo-lc l

x2

M M

M Y~~ Y Y

Y~

Y' Y Y_ Y M'

Y Y

Y Y

Y,,Y Y.

BI AXI A L II IG II FOnGE S EISMIC SIM U L ATOR O

Y i/' \\N Y A/

h

)h

~

X/ N X

?">

/X X/X j

k I

['X g

.au s.

wfp y >)<M!

y' y 2

"Jx gVX

f. 6.

~X f.

f fV X X

~

g y

/

O-X

)(

X

[

% 1

/)( </

[

l pg 3x;>g 6

s 3,pg ggg pg

/ ^

b$/

/ %^/

4 ?sg :,

A

~

hY

~

lA. f 0

m'/ N4 f v/

d ms

? 4 Nxm

1. y

'^

y x/

X 43&

A x >$NR

' ZK L"

x A E 7 I

M -

y TR A NSIENT x i,

-- ff N.

-d ao

.Y j

t l

-K

3. n~ /\\j

- X M.IN2MS'n

YL" 2Q<L'

/ h'[,

M j

/XjX2

/)"

x, N.

--IIORIZONTAL k s

N R rfc

.' '. /

p>

/

/

/

/

X 9

/

.. y 3

\\

)

\\ )

V

/

/\\ )

p

)

j' h

M

/x, :(,

~

s x,^A,,..s 4

1< 8xm v,199%

x g

4 x) yd,ex,x,^,sqq3

+

w,,

n 3

3 b ip Y%s' z

>Np q

x xA vw

/ x a

"<vvx z

g

' )< x..y_If@

g 'X yM f g

')Y B ji A

r

/ )

]

i

)

X[ )

+

/

D L.

om o4 os os a

too Frequency, Hz Figure 6 - Test Machine Capabilities

1

(

{

' yl..'k?! %w.t W i W Q Q 4~

.i:; t

.. s-iv.

C.> W u. N F D g r n.'d.i'*:

?-.

• • • fly,'-.

. +

m-.

1-E. ? S M f"*'C M.".~;.";. k(~-

i.I*'

--ag '*"jdhlj's2 $'. ' % {

8 57 '-

.t f

t~s'Q t.'_.F'%,, 3 yQSQ..,i." t *GR. g '.1 -: '.._

+ r. ! * : n -

W f, #

(.

y E

. 'h.Q. @aibTid,,m VJ

h.y,5 '*-I 4

s s.4s*,- e~,r.

^ -

..%'*.W. q,, --

s.-<.

1-w

m,-

.i 3 _.

. k.

.. gjW h34

-l

'V

?.W ?s ?Y.. ?l..hf.1.*?

-y g..

h.d I

da

['.?

do fl m,AB f

g 1 M e

8 r :

s

[

. H..%

g 3

gj M-S C

4

$h8eN;-::nE55sklhih%

v i

f(*!k#$!$EiEl$

9*2$!$8Niti I

B hp.@ '.:* g:. Ei' *

'.r.i. '.. J'.? '.Q '

Y.%t EUl% ,

er. ; d! N.,q?. D

. t 3nc

.s

..~; m.

y g

RSh

,;;.E

' e-1,f MS.I:

b '

' ' / i *.: ? 4,3 0 : f4 :

... i., :.; rg' j;.e v. g. : '.' - I 6

8

'S O id w< c '

.i 20%

.g-

.2,..h.i 5%g;;

. 9 i'.= i

...,,. : 'i n. r " ;.4. '.

.....m;n, E

% y' 3. g y ' : r -

n 1

..\\

. '.' i 1 Q o Q

- a_. ",i.-

,. 1 ;., v.,. s.

5 m..

• %.y. u.: s.:.,

b.M. '.

4 5! [: c Q:..

.,r.,

., c >.

ae

.3 Pf,1 0

f.74,fh:.t,.7&;:&..N T h -

2 L-L: - /;t.& L =;-h -:s:.Ei.'I:.Nh*C'

- 1l

'...i d 9n.n.: d gy.

c (1

s

. I I

TYPICAL ACCELERCtEIER INSTALIATION FIGURE 7 1 \\

.u.

\\

l c

5 l,(

g

=

( I

[

h

([$

. :f;.. s..

{'

b. ;i E

pjgy;1 0 h;!

,qn s,..

l Q ? -3. lI q q M$

p"1 2

c.

.i.,

ht..

.9t,

~ q.

.. a.. Y, 74

, ' m.i ' -

p

~

/

+

.:.p

, ~..

, X '-

l f;

,~

-g g

,/

P-

,J 7

Q..:

..:e.< <j~'h h*

)

r 7 %.

'y :

y 1

y.,

.c

-~

f ;[,('

e.gf 4t, 5.

.3-

.I eW s, s %..

. vp 7.cy.

r j'

?

~

~ ' '-

v ^

?.

s

%.)

' - \\", f!

L i

.'.a,-),.f.bbb;fg;'ei"I h'e&%ix'hi$?pf..

k i.

.ca. n w.

w

.n,,

TYFICAL LVDT DISTALLATION FIGUPI 8 13

I

'\\

4.6.2 Sine Sweep - Low level sine syeep with the variable supports to verify that the system resonance was properly tuned to the 8 to 11 Herta as required.

4.6.3 Multi-frequency Qualificaton Test - Essentially random I

motion consisting of frequencies in the range of 0.5 to 33 Hertz, with the amplitude controlled in 1/3 octave frequency bandwidths, was applied and iteratively adjusted so that the a5 spectral analy>is of the input =ctica = velcre: the required response spectra (RRS) of Figure 9.

4.7 Test Setup Figure 10 shows a typical overall test configuration. The specimen shown in Figure 10 is the 36" x 24" duct mounted in its strong axis I

for testing in the vertical direction.

Figures 7 and 8, respectively, show typical accelerometer and LVDT installations included in the test setup.

4.8 Test Procedure The test procedure is given in Apper. dix A.

5.0 RESUI.TS OF TESTS The specimens tested were excited using a multifrequency wareform whose response spectra conservatively enveloped the required spectra in I

accordance with test plan N-191777.

Figure 11 is typical of the test enveloping of the required response spectra.

Validation of tests to confirm the adequacy of the ducts to sustain the acceleration associated with the peak of the response spectra must in-clude assurance that the fundamental frequency of the duct system tested I.

coincides with the predominate forcing frequencies.

A comparison of Figures 12 and 13 shows that the fundamenta). frequency of a representa-tive duct system has been altered.

Figure 12 rhovs the untuned, hard-g mounted specimen response to a low-level sine tweep.

Figure 13 shows Q

the same specimen response to the same excitation af ter tunint with the flexible supports.

The duct / support system repre.sented in Figure 13 is tuned to 10 Hertz and will produce the most revere response possible to the excitation of Figure 9.

Testing to the Fig.are 9 response spectra with the tuned system assures that no other portibility exists which partu:ular duct to that will produce a more adverse response for a spectra - thus the validation.

9 i

5 E

a a

FULL SCALE SHOCK SPECTRUM (g Peak)

,s I

it i

I e

I Y

I I

T I,

.I I

i i

I i I j

s i

1 y

t I

,. - j i

1 i

i i 4

i

' i t

i i

i I

e b

i e

i i f

x i

i i

i r i !

i i

i t

i i i i

4

-_E._

. - - -,. - - - - + - - - ~ -

-t-+

t--

m,--*~ --- -

E s

4 UPPER Bomo i

/

7 x

r

.--------d i-- ~ - + - - -

-N E

h

.....'- N --- - - -.

p

--y n

E

"/

t 2

E

\\

sL O

I r

I i

i b

f.

I L

I I

I I

i I

l l

l t

i N

i.

I I

i 3

i I

'N

~ ;.'

T,,

LOWER BOMO 3'

8 u

-s u e y

?

i,

., i

,i

. i i

i i

1 I

8 6

3 e

E 4

~ - - - - - _ _

~ - - -, - - - - - - - - - '- *--

-*-*~~~

E 1

I i

i I

1 i

}

{

I

[

I I

l 1

e e

i i

l i

i

...,. i ii

. *. i e e is i

10 100 1000

-Precuency (Hz)

REQUIRED RESPONSE SPECTRA - 7 FECEiT DAMPEiG

(

FIGURE 9 (Full Scale = 100 g) -

i

h E

.(

]

E

{@38 'd@n e sa weis a m m

= ifM Mlf MEE!WMENiMllM E

kgr

E

.,,n. ~ymemmad, sgesg,EEEEE a

+

. m.

a.... -

(J a nngllar

?

~

a e,

w>

w 1

r

E y,.

.. y

! (N

7).

($

,..: v 4 '.

b

(

.N i

3-x i

-n, 24

.V e

l I,.,,.

' e n

i 4w.

.h.

u a. a t.

em

, m

~

TYFICAL TEST SETUP FIGUPl. 10

-s.

I I

FULL SCALE SHSCK SPECTRUM (g Perk)

(

I u

9 e

I I

_ i I

,l.

[

l l

I I

i i

- ii i

i I

i t,I.

i i i I

i,

3 j :

s I

y I

1 1

I

_..__e_ %

~_,

I I

1 i

{

e j a g

)

. ii

. i.i.

ie e

I 1-i I

I I C a

i a

i i fM t

I 1 s

I l

6 1

1 0

p r_--+-.--

I

...4^m

\\

.%. s f /

--g

.,_ _ i uaf -;

-A :_

_s

___-._. _ m __

=

,d 1

3

=

m- -

W

\\

e TRS en *

, e I

.=

1

- 7 ' RRS-UPPER BOUND sa I

T

.I e

i i

. i.

1 i-I

. l.

~ I

.li r

l' i

l.

.[

[.

. e..

{.

I a

. i.

it.

i

-[.

.l, g

UU 9 s

?

i j

7 I

E

_L ____L__,_._____.J _ L '

1 r

_ _U _._; _ _L_

a i

4 I

-+ %

8 t

E t

I L

1 1

e. l ;

=-

-r.

1.

i S,

4

..., e s ie a

... r. i i.

i

... r.. ie 1

10 100 10C0 Frequency (Hz)

REIRESETTATIVE HiVELOFDiG CF REQUIRED PEPCtiSE SPECTRA (7 FERCEiT)

[

FIGURE 11 (Full Scale = 100 g) l

( i e

l'

e 0

ALE LEVEL ACCELERATION ( g peck)

's e

o

. E

.g 9

h I

h 1

i i r

i 1

I r

a 5

y s.

_._.-._..__._._g..

-n 4

e-E w ;-.

y.

-_w i

1 i

r r

I S --

,7...--

~~ _

e.u-e.u-Em H-r i

1 T

I N

1 Q

I' I

i Ie L

q l

6 II l

I b

l 1

Il i i i

M 5,

m ye -

Y 4

- = = = = = = = >. * -

1.

y i

il l

l I

I I

^

II j

. y~

- ~. _ _ - _.

=

~ *

• 9.n.

~-

c. :

..z

- --j ca & ~

w r

1 I

I

^

Y ~ ~~,5'

~

~

C,. ~ " ~ _ _-- ~

/

g.

.m e

._.f.

Mjr.

f --

.,/

WJ.

Q r

{

I V

2-k b

l

<6-m

. i c1 v

~

l l_I rii,!I f

~ ' i

,),

j 1

1 I

i i

a i

[

[ 4 I

T a

i 1

i e

i a

i

[

4

_ w.

=

r I

b

- - ~. _ - - _

.--y..----,_-

--..A---

.. - ----~ _

N

$f

?

I r

, i I

I I

l I

a i

i I

' I a

I l

t i i i

i I

f i I I i

e i I

I i

i I

3 1

i a

i e a

a i e 3 i

e i e e s ::

g e e;:g ga g

Frequency (Hz)

UNTL"iED RESPCNSE AT CENTER CP DUCT SPAN (SEE FIGUPI 13)

F FIGURE 12

.\\

(Full Scale = 100 g)

II 18 I

e e.

FULL SCALE LEVEL ACCELERATION ( g peck)

It 5

E E

7 i

i

. i 1

i i

i i

i i i

i i

i,.

i i

r i

4

.A__

~

l 2

a 3 ' __

.___7

= =_.-B

=-

'4 -

i r

{

b I

I 1

4 i

l l

-H r

i i

i i 1 I i

t i

6 I i i i i

e

.a I

E 1

1

.I 1

I i

i

^ '-

1 I

i J__

e --- j,

-1

[

~

/

l ',

~

(

)h

._._.__-_/

.__.____7..___.__.

3--

_=:

o_. D m

_d u

--vt.

i 7

i y

i

/

.1I a

a a.

4

. __ ) j' 5

!$i i

.i i

i i

1

-S 6

ir i i i.

i i

e i

1 i i e

i i

i i

i

(

)

6 i

4 e 1 6

i i

i I

4 i

i. i

?[

i e

i i i i i r 1

i 1

i i 1

4 _ _______.____.-

_.. _ _ ~

w.

~

g 1

,F__-

H

- _ + _. _ _ _

_ _. -,.._.~.

_ - - - ~ ~

- 1.-

7 E:

=-

\\!

y~.

E i

r i

i

~

i ""*I i

i i

i ^ =

1 i

l 1

i i

e i

r i

6 e

i i

6 2

3 4

5 4 7 3

4 5 5 5 9 !)

3 3

4 5 4 7 8 9f*0 a 10'a00 2dOO 1' 0 0

Frequency (Hz)

TUNED RESPOTSE AT CDiTER OF DUCT SFAN (SEE FIGURE 12) i FIGURE 13 (Fun Scale = 100 g).

b

E '.

5.1 Companion Angle Construction The tests conducted on the companion angle ducts sho'wed that this I

type of construction is capable of sustaining the most severe safe shutdown earthquakes (SSE) envisioned for the Tennessee valley region.

Minor, highly localized failures were observed in the duct I,

skin.

These failures precipitated as small tears in the formed corners of the duct skin. They sometimes occurred near a stiffener, but at other times were removed from any discontinuity other than I

the formed corner.

Figures 14 thru 16 show typical localized tears in the companion angle ducts.

g These localized f ailures usually occurred at a low level of excita-g tion with very little propagation until tests to failure were attempted.

During the tests to failure even after fo rma tion of a plastic hinge the tears remained sufficiently closed that I

air delivery would not be significantly impaired (Figures 17 and 18).

General failure, when induced, was a gradual, sery ductile failure, with no complete separation of sections nor gross opening of the pressure boundary obtained.

These localized failures are believed to be the result of a combina-tion of the constraint at the formed corners, the small bend radii used in forming the corners, and possibly small imperfections re-sulting from damage during fabrication and handling.

The damage is not considered significant enough to justify any backfitting on

{

behalf of ducts already built nor any change in design or fabrica-5 tion technique for future ducts.

5.2 Pocket Lock Construction This type of construction exhibited an unexpected capability for sustaining the high dynamic loads.

Unlike the companion angle E,

ducts, stiffness of the joints which connect the individually fabricated sections to~ form the duct, allows some movement under reversing loads.

This generates considerable damping in the duct.

This more flexible joint apparently spreads the load path rather I

than containing it as tightly to the formed corners of the skin as did the companion angle construction.

The joint complianca, higher damping, and lesser weight of the pocket lock ducts are believed to be the primary reasons that no local failures such as were found with the companion angle ducts were observed with the pocket lock construccion.

The early local failures in the companion angle ducts (para-graph 5.1) caused considerable concern for the pocket lock construction.

It was believed at this time that the, pocket lock construction could never be qualified for the high response spectra of the plants beyond Sequoyah Nuclear Plant.

As a mid-program change a new response spectra was daveloped which represented an enveloping condition for the Sequoys'u plant and the earlier plant, Browns Ferry. 1

[..

=,

1 m,r. w :

c=h N3b N

h. 4, J.c$. 35!.:

I

p'u.5R.

R*

• y:;..... 'e.

tm...

.; <~ s..:a d.

km8!e/%w'$^$$xi.M,.~.

...r < a..:.:..': r.:'.. ::.,'.: '

f.i%.

u r-s..

I

NQhdW'h

.

968

..v w.e.syLQW %.. %.v.,:.0.'.* '. h / :.'. .. '

$, w:..;.

sdg

c. :.

e R&m6'e ^ ku;d ".g:

p. &g m[M., e,.

E 8

1. %**n,N.,

4.P J

2 I

.fy%s. 'kg:.~w:

Q.

t s;';..q -

n.

t

p..:$..

.. 'm;p..:: ?.. -

t

'n s

i. M......t.g e. = m' n.

u~

.e y

px.

.....s:.M,..M,.~w,. f@.' :. win...~.

l.

.Y.i

.e

. ~,.. 'N.s., K o'

~* a ~.y %..*Ol.f,v.

..s

,t

\\ ~ .?,'..

" %:: e

.. A.,,g

% g'g* g ' ' ' w

- d' 3 * 'n '.e*@.

C*( s 'g..., f g.

• ' * ~..'$, '.* ".,* '. :;,;.; 5,..'*;.'s

, :.....,a.

e.;

.'.4'.Q ( k4 }. N.yi g.

1. g

w.. j pa.. * -

%s f

' (' b 'y**q,T h'

M * %;ii 4Ag. ?)['.s,'.

s.'.' ':

I 2

i*.

'.*.....'..,5

.,/. ?.

... 4 ~ 3.%

• • '..'.' N... :y 'p?: t.. );.

• Q?'.s'. V te s

(

if ^l* p t~s

'e*4'h T,s

.~.

~

Tps..r!.* f, [2'T.,' s -

./ Q.... *..,.. ai

...c w

W E

~

.. N,, J. :. 2 J g,y:',: ' '.'. -

, Q,;.,.,.:y g

• h r. m' g.. ~ n%'..

• t

.K wa.17%g;

..., r

.

• r.W

...g*.

- s.w.

r.3

.... w ;,.... z.~ q.: n:.:7.?.'. ;-*v.~.s ::ystny v-Q.-;,%'.. ~, '.Y s

h$ h!.

j

?.

-r % r,.~ L m g.,# g%nj.:

b Q@$eg wg.

.....w.~

,. -M ga%m.syss S 'y.q.f.....

a.wywiw

.. v. 4t-rw ry,p

.f gs

. s.

...' 3 N.q q.p &p.

C

. g%y e Mt?d.W.Dia%?$.%

4':/&.44y.5,%y%K.c<M My,")m e

d.'. ~ ^.'.

. g%1

?

h

,w-r W.4.;..f.c; y.4.. g P... d.

,.....; W Q*:i % g, c p$*

• Q.g. T,4 L.W.;hm R

Juc.' @,

t

/.:

g.y.9,%w.p Q.t&. Mik ;'".i..; -

e ma. 5g. ' m -.

s.

c.-

s 9;n 4:?,:6dlQ: $9.i

~. m..;.. s. 4. s'..%q, te'.r.;*;,..~%,y..s-W rE 1

g

$.Elt25$ W -e-> M M 3 5ti $ M.> e.,. '

, : :".~. '. ' %. 1, :~.. A. s'a,*

u

..M-c

.n;2-u..,r q

. 4. & s,.

s.

c

..11.h.GL'hM,..

b:eXfi~dnN E L-DAMAGE AFTI.R RUN 30 l"

(CA 60X2k, Random Multifrequency Ler.s Than Upper Bound, Tuned)

FIGURE 1h lr i

l f

,f 7

s

't i

' t.d 1.

P

\\

y@.Ms 7 *'* * * [

% b./. *.

6-

'E

., s.

'.*, ;* *%=Q ~][,,h3h*,/ '.*f y. Q *J* 1.,'.' '

'.r*

.x.m c'-

2,-

g 4

p' k8./8.gg.,,w'.Q.:$*. * -$MN/[h+'$

r s

i

'^

l

,, W. $ {s[l': ;?d >. h ]U f y

• / f c

hty %, 'IdhEf$@l.dd/.f ~

'OT dkL 4 Y)d

'.~/.f.

(~.

)

.R

~'A s ' f.Yi,

'Q

- ' ja,'

. r;

.?

m.~-lc - I,-

v. :*.n..

.. r

.n,c m c.

s

+-

~ v..:.gc.

V. g),hs,gj.a%.'jQ',' * '

g

.,s....

'?;Q. Q.l::..

c

,;, / '.,. S

7.'.'%

,4.'N 1r r,

~

~

I

. j'<_ }

-"~

W '.. " O..

~ i:y ;

.~...<l'd5.;Q;ib.,bI'

. (.u %-..l:.W.r.u;:.

W

., a. a..,* *.Y,.f.

.[g. 0 5,%.. -

>gf; 3.;m'

't

,g

.?

w w

E

.,'x 5

..,.q

,s.-

me n-.,,, d

.yg;,.:...

m

..['./

Q.;;

8 4-rr

. ~. b y:.

...u b.

n

.; ' ~

g..g. pa[.

.x

.... g.:n Lt twh

,' fhm QL

~s.

. ~:' N e, m?i?p %. S 6 t

s-en.

^

s

.'t. _

~ a..a z e;.. J

.. :. :. h ;.'l.i & c..a.. % ag'.x.

n<

s-

.S t

.q-Qf &LW1&. kWM.

L u al;t.:.t M t w $^ % %

...... s: 3...'... in::,.*:.::

B 4

DAMAGE AFT 4R RUN 32 (CA 60X2k, Rando::2 P11tifrequency Greater Than Upper Bound, Tured)

FIGURE 15

.t 22 I

N

o l

l0...*.. -

'h.?" $ %.<.3,.SffT.; ;?i g.-

~

q E5 /t}l$.Cl.;16.';.

E 5;;S. '. -

,f.,,

e

,,:. " yg

' ' h. f;p w.97/P:, $ l ",. %

.I..h*' fi9i..+

-:.,f;(i5)hl'W},.$hh.,.k5h.} _ '

l

' hk;.&Mw ^

5 t

.h;.

.S,' _

.C

/

b,,

j @(b

.l.

.IM

. kin _;;llclh:- -

.W.' $lp.

,.:x? J ' l.

t -Q'

{

' i

.hR!22

&f?lfiTfi 'f'.'

54i k'$@95wr y s

f fh

'$,T y[

N l*

^t.

ti

?'.

l['1.U,3f%f!M " "Wp. As??.u -

. iM@2.55,T.. p(W

t T k, _{}g}g.

C D

l cprJ rqq.! c. ci,a

• "$ @9+ **. +V MM5%f::..

TV ; '

• p.

1,4

[Ye W '

w f

' k5.. '. I S

.[p? gtg, "' '

l.

'g"; $

h' { ; d

+

',.L'E :.,',

O

'Y-a m

f v

?

p m

?g.m.,s g.-

sn. ? j.,

a en

\\..

< < ll b

f,'.[

'i sf7;3*P We,

• y

't.

((

', fj p.Q'y,*,

r

}

e..* <,

,C

,.e 3,s ?

h 1 g

s ),

[9 t

jJ

~.'

e-

n..

m l

G, E

w i

g.

l DAMAGE A"TER RUN 40 l

(CA 36X24, Rando:n M11tifrequency Upper Bound, Tuned) l FIGURE 16 4 i

I e

~

4

-.,...,.~.

dr..V'-

J..

ww!mTe m?

]

l-

.W k'.

WW' g.

-ww

-r u, A,f.

c.y-f Q $ $" 8' s g O c e * * '.

e LkAEN35

L:miasNI

$h.$hk h.' h h?"h Y

@Y'

~

MhrsrL Lj~t s-A-+---

y q~.. ~~rmt wm.. 3

=-

~

1*-~: & *<

^^

f,.} vd. -

\\\\

t

, = ;

ihrsa NK '.

__ -. 44.

\\ttL *F i

r-TET RUN hk - TET TO FAIUJRE

• P[

(CA 48X18, Random M11tifrequency, 80 Percent Above Upper Bound, Tuned)

!!B FIGU?I 17 i

i.

4

8 ga e

e e

f I

3 1

j

{

.. j';

m

'i a

1. g&

_-.q.

2 9 ?.; %y 4

%.1.@

98 n

(.; Y%$m%9.h

}.

cp

.L.(%g 1 *.Ej 1

^ 3

%;".;e? ?w...

.: x

., e N

.J 4&

k!?

7

',d

.N

1. n :y$lJ h.

1 s: *

' l y 4 a -

. '., ' I i ' '..+

/

I F

'h i.

p f, 1/Y)A i 1 ESj ";qp.Efh,jEg

?

p!

. '{

))

. Oe L

'I iqt i if;.

1

' $,' {;SkiQ ' ?

'g g

' h.

y

?.' !

.;l.,s;U:}ff;;k.s.i,=!:.

' 'm,..

ig

.. sl. -

a 2

.p. :.v. % 'O 'l is

.n>; y*6

.;-;9;r-

e ll'

.l.

l.j.-.

e.. r J' *l' ' W f.

{

... : 1 t

% 'l

' h, 4' ' j, * 'm,f h

)j'a, Q$%,.j., '

'h,'i.

$>_jl'lk}:l;f,.

.,., 1.

7'v t.

"'~

O, <

. p.

.; %._.fm. m.e. ;,

y....

.x n

-8..

w.

.y

.;g r. i.a v

.~. -

s

/

w T$m.9en. n -

. v.. -

.; ca,u M sc I

M ].,4 ~',, fee-i. g7

.w h

'o n

.:u..

1., - ~

.*.a a..e

...$? a

~

.K --:f'*

Y 9

4.,. il '

g

r...cm._w

.g VIEW INSIDE SPECIMEN AT COMPLETIGi OF RUN h4 FIGUP2 18 E i

g-F

~~

This change t'emporarily altered the initial objective for the pocket lock tests-the new objective being to qualify the pocket lock for these two plants, where some of this type construction had already l

been used and to disallow its use on later plants. However, as testing began on the first pocket lock duct, the duct readily sur-

I vived the low level tests.

Next, the duct was subjected to the full level (upper bound) of the modified spectra.

No adverse affects were noted.

Ordinarily, after survival of the upper bound of the required re-sponse spectra, the duct is considered qualified and is then in-crementally tested to increasingly higher levels until general failure is induced or until machine limitations are reached.

In this case however, based upon the duct's response to tne codified spectra, it was decided to test it to the original spectra v'tich I'

envelopes.all TVA sites in the Tennessee valley.

The upper bound of this spectra was reached and there were still no indications of failure.

Subsequent tests to failure of this first pocket lock specimen revealed that not only did this duct survive the maximum seismic loading for the valley, but it also demonstrated a reserve strength beyond the maximum required spectra.

Tests on the remaining pocket lock ducts utilized the original en-veloping spectra for the valley without consideration of the new and lower level spectra. Throughout these tests no failures of any kind were observed at test levels at or below the upper bound of the original response spectra.

The only anomaly found was a slight post-test sagging of the duct spans due to loss of the initial clamping action of the pocket lock crimping at the joints.

When it was possible to induce general failure of the pocket lock g

ducts, the failure mode was usually a sudden opening of the crimped g

joint.

A sudden, catastrophic type of failure resulted and actual separation of duct sections caused the span to fall to the test table.

These failures always occurred at test levels considerably higher than the required response spectra.

Two of the pocket lock ducts could not be failed due to force limitations of the test machine.

6.0 C_0MPARISON OF TEST RESULTS WITH TEST OBJECTIVES 6.1 Phase II, Test Objective A (Paragraph 3.2A) 6.1.1 Objective A:

r 1.

Demonstrate that SMACNA-constructed companion angle and pocket lock ducts possess adequate dynamic capa-bility to withstand the maximum TVA safe shutdown earthquake, fg E i

s

2.

Show that these ducts may be considere as load-ca rrying *-

structures whose performance is prei.ctable by conven-tional analytical techniques.

j 6.1.2 Discussion of Test Results vs. Objective A:

1.

Tests of six different ducts (with six different propor-tions of width-to-depth, where depth is in the direction of the test axis) for both types of construction have shown that the ducts can withstand the maximum envelop-ing response spectrum.

Furthermore, considerable reserve strength was demonstrated above that required to resist the maximum safe shutdown earthquake, af ter wna the need for repairs is an acce' ted part of the basic p

design philosophy for nuclear power plants.

Y 2.

In an overall sense, the duct survivability demonstrated 4

during the testing proves the predictability of the performance of the ducts, which were analyzed by conven-tional techniques.

In the finer sense, however, detailed characteristics such as natural frequency (and the interrelated parameter moment of inertia and section modulus), skin stress, and support loads were conservatively but not closely pre-dicted.

(See Table II and Figures 19, 20, and 21.) Even though this program was not primarily a data gathering effort, the test data obtained may provide a basis for correcting the predicted values to bring them into closer agreement with the test results.

Since the range of duct sizes tested is f airly representative of the sizes used in the TVA plants and since the important overall per-formance was established, the preciseness of the e

l3 predictability of the detailed characteristics is gen-E erally of academic interest only.

6.2 Phase II, Test Objective B (Paragraph 3.2B) l 6.2.1 Objective B.

l Establish the margin of safety in the seismic qualification method described in TVA Design Guide DG-M13.1.1.

(

6.2.2 Discussion of Test Results vs. Objective B l

There are many ways in which margin of safety may be defined.

It could be defined in te rms of stresses, applied loads, l

reaction loads, or deflections.

For the purpose of this discussion, the margin of safety is defined in' terms of the

!r peaks of the required response spectra and the test response spectra.

i 4

g,-. g g, g_, g-,. g. g, g, g, g. g. g g

g g

g_

TABLE II STRESS DATA POR UPPER BOUND RUNS (Computed, Measured, and Normalized)

(A)

(B)

(C)

(D)

(E)

(F)

("

4. fl)

>W N.

M 3

5 Bending Section Computed Measured Normalized Span Type Wt/Ft.

Moment Modulus Stress Stress Normalization Stress 7.

Duct Size Test Axis (Feet) Const.

(Lb./Ft.)

(In.-Lb.)

(Inches 3)

(psi)

(psi)

Factor (psi)

W/t 60 x 24 Major 28 C.A.

51.6 388,400 49.8 7,800 10,500

o. 90 7 8,300 t 668 P. L.

45 0 338,700 50.5 6,700 5,400

o. @

4,800 2 48 x 18 Major 26 C.A.

37.o 240,100 26.h 9,100 6,300 0.853 5,300 ; 602 P.L.

31.0 201,200 D

7,500 3,800 0.762 2,900 t 36 x 24 Major 22 C.A.

30.6 142,200 15.6 9,100 15,000 0.780 11,700 4 803 P. L.

27.0 125,500 15.8 7,900 7,500 0.842 6,300 1 24 x 60 Minor 16 C.A.

51.6 126,800 9.0 14,100 6 21,000 0.61o_

12,800 4 1671 P.L.

45.0 110,600 91 12,200 8,400 0.762 6,400 0 18 x 48 Minor 14 C.A.

37.0 69,600 h.2 16,500 21,000 0.889 418,700 1 1605 P.L.

31.0 58,300 h.3 13,600 6,000 0.762 4,600 1 2h x 36 Minor 16 C.A.

30.6 75,200 7.4 10,100 9,600 0.853

.8,200 t 1204 P.L.

27.0 66, hon 7.5 8,900 6,600 0.744 4,900 {

1.

Type construction, C.A. = Companion Angle, P.L. = Pocket Lock.

2.

Bending moment computed using peak of R.R.S.

(6.hg) distributed uniformly along span.

3.

From AISI effective moment of inertia method, extrapolated to higher W/t values.

h.

Stress computed from strain gage closest to corner and located in the plane of the top of the duct.

5.

Normalization factor adjusts the peak of the TRS to the icvel of the RRS (6.bg) only.

h[7 l'

7 b.[

6.

Data not discernable for upper bound run.

Data from next higher run used, then normalized to 6.hg.

7.

W = Duct width relative to axis of test and to skin thickness, t.

('.

g l( f 3% (1 g

)

5

..J q,

~pm

. p,.

A

' S, S Ih. " ' ' '

[. b O.

h, gg b

~

M

/

U,, c h i_! = o 1l6 V Y

4

c. c

g MEASURED AND CALCULATED DUCT SKIN STRESSES (SHOWN ON QUARTER SECTION)

~~~

l FOR UPPER BOUND SPECTRUM 800 g

TYPE CONSTRUCTION

[-

S COMPANION ANGLE l

_9,100g O POCKET LOCK I

l c-I 9,100

/

}

i I

r-

\\

\\

\\

\\

\\

1

\\

\\

\\

t u

1 RUN 31 I

RUN 15 RUN 40 g

I 1

\\

s s

s t

t t

60" x 24" 48" x 18" 36" x 24"

[

14,10 0 g

r- -

\\

l

\\

\\

\\

RUN 52 q

24" x 60" 16,500 F-

~

\\

\\

RUN 61 10,l0 0 2

p 18" x 48"

{

~

- --- COMPUTED 1

MEASURED (NORMALIZED TO 6.4 G )

\\

. c.

@ AISI EFFECTIVE MOMENT CF INERTIA

\\

I

@ UNIAXlAL, LONGITUDINAL RUN 68 g

~

24" x se" l

FIGURE 19 29 I

e MEASURED AND CALCULATED DUCT SKIN STRESSES (SHOWN ON QUARTER SECTION)

~

E F " """5" S ""

SPE '"""

~

6,700 TYPE CONSTRUCTION l

r-O COMPANION ANGLE lb 7,500 O POCKET LOCK r,

g k

p"

),

\\

7,900

\\

\\

t 7-

\\

\\\\

\\

\\

t t a

t

\\

\\

RUN 10 0 I

RUN_89 1

RUN 82 s

J a

t t

E 60" x 24" 48" x 18" 36" x 24" r7 M 2OO Ib k,

V

\\

\\

\\

RUN 12 7 sS

~

r t

n 600 l3 24" x 60" I

_ M--___

1 k

\\

\\

RUN 119 8,900 E

18"x 48" r

1 g

---

COMPUTED MEASURED (NORMAll2ED TO 6.4 G )

\\

(-

\\

@ AISI EFFECTIVE MOMENT CF INERTIA

\\t

@ UNIAXIAL, LONGITUDINAL

\\

RUN llI v

24" X 36" FIGURE 20

t..

j k-VARIABLE SUPPORT DEFLECTION / FORCE.

FOR UPPER BOUND SPECTRUM g(TEST FlXTURE END FRAME)

DUCT TEST SPECIMEN i

. VARIABLE SUPPORT

{

{ 7 98 MOUNTING BEAM 48 TEST TABLE h

d F(f) 24" 1.

2.

3.

Q l.

2.

3 DEFL.

FORCE FDRCE DEFL.

FORCE

?W RUN (8)

(#)

( ## )

(8

)

(# )

60" 31 CA O.24 3000 5400 CA O.24

_?000 LOO PL RIGlD 5100 PL RIGID 28'- O" 18"

_g i

i 15 CA O.26 2lOO 4500 CA O.27 2l00 48" 89 pt RIGID 4200 pt RIGI D

.t 26,-O,,

24" 40 CA O.27 1700 3300 CA O.27 1700 0.20 1200 82 a 0.17 1000 3200 22'-0" pt, a

u 60" 50 CA O.20 1700 4200 CA O.27 2200 12 7 g 0.17 110 0 4000 PL O.23 1400 24" 61 CA O.25 1500 3400 CA O.28 1700 48"

^

14,-0,, pt, 0.30 1800,_,

18" l19 PL O. 15 900 3200

^

36" O.26 1600 3400 68 CA CA O.26 1600 11 I pt O.13 800 3000 PL O.13 800 24" l

16' O "

t CA-COMPANION ANGLE CONSTRUCTION

=

PL FOCKET LOCK CCNSTRUCTION

. i

1. MEASURED DURING TEST (PEAK)-NORMAL.iZED TO 6,4 G l

2. COMPUTED FROM l. AND SUPPORT CALIBRATION CURVE-NORMALIZED E 6.4 G l f.

3.FROM DESIGN GUIDE DG-M 13.1. I ( INCLUDES WElGHT OF END FRAMES) lg FIGURE 21

1',,

3 T

-R F = p g

Rp T

F

=l (2) 3 R

P l

where F = Margin of Safety g

I g = Safety Factor F

T Peak Value of the Actual Test Response Spectra at P

General Failure of the Duct R = Peak Value of the Required Response Spectra B

p t

The results of the test program demons: rated that ducts supported in accordance with Design Guite DG-M13.1.1 do possess definite margins of safety relative to the required response spectra.

The tests results show that margins also g

exist in terms of duct skin stresses and support loads although no attempt has as yet been made to quantify these B

values.

6 The definition of margin of safety as defined in equation (1)

E,,

is an extremely conservative one.

It is conservative in at least four ways:

,g 1.

As the peak is increased in attempt to induce failure in F

the specimen, due to the machine controllability and the effects of subharmonics and multiple harmonics, virtu-ally the entire spectra is increased in level, not just the peak.

2.

As the input frequencies and levels are adjusted on the shock waveform synthesizer to envelope the required I

response spectra, subharmonics and multiple harmonics of the test mechanical, structural, and hydraulic systems come into play and result in a conservative broadening of the spectra peak.

3.

As the dynamic loads are increased and as structural damage is incurred, the fundamental frequency to which the physical duct / support system was tuned shifts toward the lower end of the frequency spectrum and away from the primary forchg frequencies.

After this occurs and due to other nonlinearities, the peak of the actual test l

response spectrum is suppressed, not fully representing the severity of the test to the now softened duct.

4.

By the time an actual general failure is, induced, each specimen has experienced many normal lifetimes of I

vibrations, including the equivalent of several safe shutdown earthquakes.

Consequently, the duct that fails is not a new duct.

Rather it is a very old piece of equipment which embodies the cumulative effects of a k.

T tremendous number of cycles of all force levels and fre.

quencies of vibration.

A,new duct tested to failure on the first attempt should exhibit a much higher margin of E.

safety.

Table III shows the margins of safety and the safety factor for each axis of t e's t in terms of the definitions given in equations (1) and (2).

6.3 Phase II, Objective C (Paragraph 3.2C) 6.3.1 Objective C:

Provide data which will allow as much balancing as possible between economy of design and safety considerations.

6.3.2 Discussion of Test Results vs. Objective C 1.

The first obvious economy demonstrated by the test pro-gram is that the SMACNA standard for companion angle and pocket lock duct construction, when used in conjunction with TVA Design Guide DG-M13.1.1, provides a safe system.

Others have taken approaches which led to much heavier duct construction requiring note expensive joining techniques, and have undertaken much costlier test pro-grams to perform the same functions that are provided by the TVA approach, under which no new duct design is necessary and long standing fabrication techniques are followed.

2.

The testing demonstrated that the deadweight support spacing recommended by SMACNA (and increased by approxi-mately thirty percent in DG-M13.1.1) can be significantly increased.

The testing was conducted using no supports other than the seismic supports (restraints) specified in DG-M13.1.1.

Therefore, since they were not used in the tests,- these intermediate supports are not required in an operating system.

The savings of ommitting the intermediate deadweight supports is a great economy measure.

3.

Characteristic values of damping were determined for both types of duct construction tested.

As a result of l

this, justification for the use of the seven percent lf curve is complete.

Also, the pocket lock construction which exhibits greater damping can utilize a lesser spectrum.

By comparing the failure spectrura to the l

higher damped required response spectrum, (approximately greater margin of safety for the ten percent), an even pocket lock construction is evident. Table IV summarizes the damping values obtained for the various duct sizes and construction.

I 1

l.

I l_

t,..

TABLE III MARGIN OF SAFET AND SAFETY FACTOR FOR D,UCTS TESTED TO FAILURE 2

Peak-G

' Margin of

,3,f,ty

}

b Failure Run Duct Size Test Axis

-Companion Ang1e-4 35 60" x 24" Major 10.2 0.59 1.6 3

u 3e x 24-Ma3or 10.5 0.64 1.6 3'43 48" x 18" Major 11.2 0.75 1.8 56 60" x 24" Minor 14.0 1.19 2.2 4'64 48" x 18" Minor 12.3,

0.92 1.9 71 36" x 24" Minor 13.6 1.13 2.1

-Pocket Lock-3'83 36" x 24" Major 11.0 0.72 1.7

'95 48" x 18" Major 16.2 1.53 2.5 105 60" x 24" Major 14.5 1.27 2.3 3*112 36" x 24" Minor 12.0 0.88 1.9 3 120 48" x 18" Minor 11.5 0.80 1.8 131 60" x 24" Minor 16.0 1.50 2.5 1.

Margin of Safety, F

=b~b 3

R P

T = Peak value of actua1 test response spectra at P

fai1ure R = Peak value of required response spectra (safe P

shutdown earthquake) = 6.4g 2.

Safety Factor, Fg=

P 3.

Failure actually occurred during next run.

4.

so,e. era 1,a11.re s. fore mac,1.e 11.itat1on.as reac,ee.

L

.I I.

k E

e R

~3k-r

,q[.c...

l

, l TABLE IV 1

SUMMARY

OF_ DAMPING MEASUREMENTS I

+

Percent Damping Percent Test Companion Test Damping Test run(s)

Duet Size Axis Angle Run Pocket Lock 22, 23, 24, 60" x 24" Major 7.1 97 10.8 25, 26 8, 9, 10 48" x 18" Major 6.5 No Data 37 36" x 24" Major

• 4.3 73 8.2 46 24" x 60" Minor 7.9 123 9.9 58, 59 18" x 48" Minor 5.5 115 9.7 66 24" x 36" Minor 7.2 107 9.7 Average 34.2 + 5 = 6.8%

48.3 + 5 = 9.6%

• Appears to be erratic data - not used in ave a ir g ng.

6 4.

Q._ ~ w m _, - m e ~ _ _. - -

l

,,c.

p Y

h.

7.0 POINT OF INTEREST The method used in Design. Guide DG-M13.1.1 for computing maximum allowable span lengths appears, from the results" of the tests, to p'

a rather optimum upper limit span for all duct sizes.

The prescribe method utilizes the following equation in which all constants and units have been incorporated into a single coefficient in the equation:

6 f

(3)

" II where 1 = Maximum allowable distance between supports (for either axis) in feet, 4

I = Effective moment of inertia of the duct in inches, and

-~

w = Weight pounds per foot of length of the duct.

Implicitly included in equation (3) is the condition that the span f

length, acting as a beam and using beam theory, is such as to limit the first mode fundamental frequency to 33 Hertz.

Measurements of the first mode fundamental frequency show that this span length overestimates the actual fundamental frequency by a considerable amount.

The natural frequency is used only as a tool for limiting the span length and has no other significance in this procedure.

The span length however, is the important factor for the context in which eqt.ation (3) is used and this method appears to give good results for span length predictica.

(See Section 8.4.)

The computed values, fer the ef fective moment of inertia using the AISI method utilize a small portion of the duct width as an effective flange but assumes the entire depth of the duct effective as a web.

Conse-quently, the very deep ducts might be expected to be in less agreement with computed values than the shallow ducts where more of the web is actually effective as is. assumed in the AISI method.

However, there appears to be no such phenomenon indicated.

This suggests that the increase in W/t ratio is just as influential as is the decrease in the depth of the duct (see Table II).

1 Even with this lack of agreement of duct stress distribution and resonant frequencies relative to predicted response, the method used in Design' Guide DG-M13.1.1 provides consistently conservative enveloping results for all duct sizes and types tested.

Consequently, natural fre-quency of the duct span is merely an operator to arrive at the distance between supports, no further effort will be expended to attempt to improve the method.

As a matter of interest, but not important to the analyses involving HVAC duct supports, the fundamental frequency of the duct span can be more closely approximated by multiplying 33 Hertz (implicit in equa-tion (3)) by the following factors:

for companion angle construction, frequency correction factor = 0.46-0.62 for pocket lock construction, frequency correction factor = 0.35-0.44,

f o r s.

8.0 ACTIONS BEING TAKEN AS A RESULT OF TESTING 8.1 The requirement for deadweight supports at spacings derived from the SMACNA s*,andard are beint deleted.

As a result of these tests it was found that the seismic re s *.ra ints for Seismic Category 1 E

Systems aise serve the deadweight function without intermediate T

supports.

Instructions will be given accordingly.

]

8.2 For non-seismic Category 1 Systems, it was found that deadweight 9

supports can be designed to the same spacing requirements as given for seismic restraints on Category 1 Systems.

Instructions will be giwa accordingly.

8.3 As a result of the tests it was found that support loads for ducts of pocket lock construction can be derived from nine percent damping spectra.

Instructions will be given accordingly.

For companion

4 angle construction, seven percent should be mantained.

8.4 As a result of the tests the equation which was previously used to predict natural frequencies of a duct span is being changed.

The j

previous equation, based upon the beam equation, is I

I E

n (4) y 288L i

where K was taken as unity it should now be taken as 0.46 for companion angle ducts and 0.36 for pocket lock ducts (See 7.0)

L = maximum support spacir.3 in feet E = Youngs modulus of the duct in psi 4'

I = Effective moment of inertia of duct inches g = Gravitational constant (386 in./sec.p7 L w = Total duct weight per foot (including insulation)

L The equation for maximum span length, equation 3,

will remain j.,

unchanged :;ince it has been shown by these tests to result in an optimum compromise between economy and conservatism.

However, the basis for the constant, 11, no longer presumes a 33-Hertz rigid

?

span.

Rather, it represents an empirically verified constant which brings theory and test into acceptable agreement.

9.0 RECOMMENDATIONS Ii l

9.1 These tests were originally conceived and were belemented primarily i

as a qualifiestion and fragility determination program as opposed to A

a data gathering and research effort.

Limited instrumentation was later added to confirm the overall observations and provide limited insight to stress, acceleration, and support reaction levels in the lr ~

event that failures occurred below the qualification level.

Even

'L with limited instrumentation, because of the large number of test g

runs, a great amount of data was collected.

s

[e.. <

.a.-

?

As used in DG-M13.1.1 this method was extrapolated into a region of,_

4 high width-to-thickness ratios for, which it was not originally It is recommended that consideration be given to possible intended.

use of these data in improving the accuracy of the AISI effective moment of inertia method in regions of high" W/t ratios (500 to 2,000), and in better predicting the stress distribution across the flanges and webs.

A proposal could be developed describing the j

objectives and technical approacn to such an undertaking.

9.2 This test program included companion angle and pocket lock con-struction ducts.

Circular ducts have well known properties and behavior and can be qualified analytically.

Flat-oval ducts, how-position someplace between the circular and the ever, occupy a lightweight rectangular companion angle ducts and their properties and dynamic behavior are not well known.

i Utilizing the existing fixturing, calibrated variable supports, and test procedures, it is recommended that a series of flat-oval ducts be tested in the same manner as were the ducts of this program.

This would close the duct qualification issue for all of the types.

presently in use by TVA.

l

)

10.0 SLWiARY r,

The results of these tests have allowed for fulfillment of the three test objectives stated in 3.2, Phase II (see 6.0).

Of more direct importance the testing also concludes that:

1.

Even though the actual duct fundamental frequencies and internal stress distribution are not precisely predictable, the important overall performance is enveloped by the TVA method of analysis.

2.

The companion angle and pocket lock construction HVAC ducts used on previous plants- (Browns Ferry through Bellefonte) may be considered to be seismically qualified where d.esigned in accordance with SMACNA and supported in accordance with the respective TVA plant specific design criteria.

angle and pocket lock duct will be seismically qualified 3.

Companion designed according to SMACNA and srpported in accordance with when Design Guide DG-M13.1.1 for plants beyond Bellefonte.

Another very important aspect of the testing is that it has been shown that it is not necessary to design special heavy gage duct for seismic applications as others in the industry have done.

This allows for the continued use of the same SMACNA lightweight construction which has long been used in industrial applications, and for which TVA has fabrication equipment, tooling, knowledge, a ttd great experience in its fabrication.

A recommendation was made, paragraph 9.2, which, if followed would close the issue of HVAC duct qualification for all types of ducts currently being used by TVA. 4