TOTAL OF 10 PAGES ONLY MAY BE,X,S$OxE?

O E W E P O R N-UNRUND SiUDl6S

TOTAL OF 10 PAGES ONLY MAY BE,X,S$OxE?

I

CANADIAN THESES ON MICROFICHE

-

I

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^?SEN

,

CANADIENNES SUR MICROFICHE

-

NOTICE . AVlS '

he W ~ I P Y of thls ikrofichs is heavily h p n d d qualit* do a;.microfihe d i d gnndermnt dr upan th. qualify of thc ~ r i g i n a l thesis ~vbmiffed for la qualild do la lhdw soumix au%rmfi!Mw., !om mlcmfilm8ng. Ewry ellaif has bnn glade to enrure lronr l o v l fan( pour asun+une oual#t= ruprlaun the hlghaf quality o f mwoducl~onparibD. dr repmdurtioo.

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THIS DISSERTATION LA THESE A

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HAS BEEN MICROFILMED

.

M I C R O F I L M ~ E TELLE OUE

EXACTLY AS RECEIVED NOUS L'AVONS RECUE

"1.319 I? 811011

Canad3

I *

STRUCTRUAC DESION AW ANACYSIS OF CONCRETE SANDWICR PAMEL6 IMD THEIR

I PPACTIUI. APPLICATIONS

._

I ^I

@

r u t h u r x i - = i t sung, . P . E ~ . , B . E W .

I -

A t h s e i a s u b m i t t e d i n p a r e l

I f u l f i l l m e n t o f Ule i q u i r m n t ~

,

for t h e d e g r e e oi

I m s t e r of E n g i n e e ~ i n g .

.

. .

ncuity or E n g i n e e r i n g and ~ p p l i s d s c i a n c s ''L.

i

M a o r l a 1 u n i v e r s i t y o f ~ e w f o u n d l a n d

. 1'.

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December, 198,.

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..-. -- _'.. 1 -

A I -

. .

.

.

' -

.

The c o i c e p t of a % o n s r e t i e a n d u i s h p a n e l o r i g i n a t e d i n ,

.-

t h e u n i t e d s t a t e s I n 1906 where a b u i l d i n g w a s e o n e t f u c t e d

.

.

, -

.

. - . ,

w i t h sandwich tilt-"@; p a n e l s . s i n c e then sandwich p a n e l a

.

h a v e developed gradrially a d d have continued to.improve.

.

,

There a r e No.typea of c o n c r e t e sandwich wall panels: ^,

I ,

. .

^,

11) 1 r o h i t e c t u r 0 1 w a l l p a n e l ~ Inon-mmpaaite type)

,

^and

i

121 ~ o a d baaring w a l l p a n e l s icompoaLte and mn-composite t y p e ) .

'.

^'

I n g e n e r a l , t h e non-composite typ;

&

l o a d b e a r i n g p a n e l i a u0.d more c ~ m o n l y because t h e r e are less l i n i t a t i o n ~ compared

'

w i t h t h e c m p o a i t e t y p e @ .

.

This ths.1. d i a l s with Uie

s t r u c t u r a l depigi, a n d a n r > y a i s o f - tha non-mmpoaite type o f ' ' ^' load* w a l l p a n e l .

I n t h e p a s t , certain problems b a s e t t e d a r c h i t e c t * , i

' ' e"gineecS, end m n t r a o t o r s working w i t h o w c r e t e sandwich p a n e l s . '

These p r o b l m s p r a ~ s m c i a t e d with;'

.

11) 121 J o i n t s i n panel Bonding between colicrete and i n s u l a t i o n

: . . .

..

. I

13) P a n e l m n n s c t i o n s .., 1

i '

I41 c o n t r o l of cracking.

-

.

I

. mi.

s t u d y hall bsan u n d e r t a k e n w i t h the aim of a o l v i n g

1

some of t h e s e problems. T h r e e ;xpe;imento w e r e mnductod .

.

ⁱ

, a c c o r d i n g l y to d a t e m i n e t h e behavior o f concrete sandwich p a n e l s . The f i r s t exporimant uaa t o i n v s a t i g s t s t h e e f f e c t s

. i

. .. _{. . ,} ^-

ⁱⁱⁱ

^-

^{' ,}

_{. .}

"

,

.

e ~ p e r i m e n t a l r e s u l t s w i t h t h e o r e t i c a l a a l o u l a t i o n s . The

.

, p r i n c i p a l re:ults q f t h i s expsriment denonstraced t h e e f f e c t * on c o n c r e t e sandwich panels under v a r y i n g thermal c o n d i t i o n h .

.

, T h e s e r e s u l t s should serve a8 a g u i d e l i n e f o r the debign o f

.

I

j o i n t a i n &ndwich panela. The second a n d . t h i r d experimgnts . ,

were i n i t i a t e d t o i n v e s t i g a t e an3 conpare t h e bending stresses., d e f l e c t i o n s and a h e a r s t r e n g t h i n m n c r e t e sandwish p a n e l s

. . , w

e i t h e r w i t h

,

o r w i t h o v t s h e a r con&ctore.

.

The panela were-

. .

^,

.

subjected t o a e m u l a t e d u n i f o m d y d i s t r i b u t e d load under simply s u p p r t e d . e o n d i t i o n a . I t can b e concluded f r m t h e .experimental r e s u l t s t h a t a well d e i i g n e d anchor s y s r e n j o i n i n b

tha concrety sandwich panel fasea through t h e cors i n s u l a t i o n

. .

i a a rundamental mquiremenr i n t h e f v t u r s Production of

'

.

spndwich w a l l p a n i l s i n 0 r d e r . v o b < a i n f u l l shear t r a n s f e r b e d e e n t h b faces. Without th8.e s h e a r connectors, a m n c r o t e s r r u c t u r a l sandwich panel w i l l u s 6 a l l y f a i l by.ah&r of t h e

, . * . .

bond between t h e mra and f a c e s or by ihear f a i l u r e o f t h e

core i r a e ? f . .rl

;

_I

:

The d e f l e c t i i n on a sandwich panel i a t h e . 8 ~ o f o r d i n a r y

t e n s i n g d e f l e c t i o n and an a d d i t i o n a l d e f l e s t i b n a s s d c i a t a d

' 1 .

with a h a s r d e f o m a t i p n of t h e cqre. E x p s r i m n t a l r s p u l r s ahovsa t h a t d s f l a c r i o r i . mainly a i a a s i a t e d with shes; deformation of t h e core f o r p a n e l s without s h e a r connectors.

. , !

/

DBflectione measured were l e s s for panels containing shear connectors. For both panala, f m m t h e o r e t i r r a l c a l o u l a t i o n e , i t was foynd t h a t t h e d a s l e c t i o n s usre mainly associated w i t h

ahear de€ormcation, with' lea. than 1% due td banding. ^' A p r o w e s h e a r conmotor system t r a n s f e n s i l l l a t a r a l

. ¹

l a d s i n c l u d i w wind f o r c a s f r o . the e x t e r i o r f a c e to the

i .

i n t e r i o r s t r u c t u r a l (ace df tho panel. Hence tho sleeve anchor, t o r a i m anchor. and oonnector p i n s p l a y a very imporrant p a r t

I i

i n +he perfo-nse of'conorete sandwich p a n e l s . P b s t r a a a i n g technique. can a l e 0 improve the d e s i g n of s u c h p a n e l s and have

,

basn widely used i n resent d e v e l o p a n t e of sandvish panels.

i ^"

Far thfs e M y , a t y p i c a l nowcomwaite type of s o n c r a t e sandwich p a n e l was .elected as a design axampla. For the design of auch concrete sandwich panel., the f o l l w i n g faator.

i

,

ware c a r e f u l l y considered8

.

^\

11)

me

t h i c k ~ e s s o f b o t h f a c e s of the p a n e l ( 2 1

me

loading c o n d i t i o n s

(31

me

f l r e resimtanee of the sandwich p a n e l ( 4 1 me temperature g r a d i e n t between the f a c e s , and (51

~ h d

panel anchor my-ten.

!

-;v

- ; B

.# '

t .

'.

: , -

The.suthor would l i k e t o express h i s ap6rsciation

/I

to D r . A. .i.:chriqtian. ~mfassor i n c i n x Bngineering.

.

^'

. .

memorial Univeeeity o f Newfoundland, fir hia valuablq

1;. ^{n u , .} .*

^{u.i.u, thi. dleit.}

t ThanLm are alao extended t o MI. Roger Flood. M r . Roland

I

^"

I! ^:

m d d i n o t t and

m .

my ~ i f f l i n , of l i t l a n t i c Concrete ~ t d . , f o r contLibutlng the two oonerote sandwich panels for t h i s

1

p r o j e c t .

I

P a r t i a l support of U l i s p r o j e c t from t h e N a t i m e l Research

/

c o u i c i l df c a h d a , Grant no. 1-0992 i s g r a t e f u l l y acknowledged.

. .

I

P i n a l l y , the author wishes to thank Ilr. mny rn&te, S u p w i s o r of Laboratories, and a l l the technicians i n t h e

I I

^{StXUCtU.1 *oratory} and Welding Machine Shop of ~ d . i a l

1

u n i v e r s i t y of Newfoundland for t h e i r aaaA8tanre

In

car

P

i n g

/ ^I

I

I

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'

1

I

I

I P

-- --

I

TABLE OF CONTENTS

Page

, 0

msTRRCT

1

ACI(NO?lLEOFF*(ENTS li

T B L E OF NlNTENTS

,

i

LIST OF TIBLES

LIST OF FIGURES x I i

LIST OF P-TES xk I

>

(

CHAPTER I.: INTRODUCTION 1

)

CWPTER 1 1 . HISTORICAL DEYBWPIIENT OP 03NCREFE

t /

SANDWICH PANELS 3

* ,

' 'CHIPTER IV.

I..

-

.i. . , . ^{4 . 1}

. ..

^{4 . 2}

4 . 3 4 . 4

,

-

, .

TYPES OF CONCRBTB SANDWICH WffiL ~ANELs 7 A r c h i t e e t u x a l panels. 7 laad B e a r i n g p a n e l ) 8

.

~ a f cmpositb p a n e l a 8

ibl N o n - c o n p o s i t e ~ p a n e l s - 8

PposLENs AND PEWORHANCE OF CONCRETE

SANDWICH PANELS 10

B o n d i n g between concrete and i n a v l a t i m 10

J o i n t s i n p a n e l I 1

p a n 1 a o m e c t l o n ~

.

12

C o n V o l of cracking I 3

4

-

"ii

-

'CHAPTER V. THIRHILT.; CREEP I H D SPRIWKAOE EFFECTS

om

mircrrem

smmlce

w r w . PAIIBLS

5.1 , e e n r r a l

1

5.1.1 n a i n t a i n i n g a d e s i g n f a c t o r of h e a t t r a n u a i s a i o n ~ ( 6 1 1 value 5.1.Z B u l g i n g

.

I

5.2 E f f e e t e o f creep, s h r i n k a g e and t e e r a r v r e c h a n g e s an c o n c r e t e

'

..

s a n d v l c h panels ,

.

,

,

5.2:1 C r e e p 5.2.2 S h r i D L a g e e f f e c t s

.

I 5.2.3 T e m p e r a t u r e e f f e c t s

I

-

P a g e

1 .

5.1 E x p e r i m e n t o n h e a t i n g and of

.

:

' s a n d v i c h p a n e l 3 8

5.3.1 T e s t i n g m d t e r i s l ' '

.

3 8 '

5.3.2 T e s t i n g o f , h e a t l n g e f f e c t s o n , . s l m d u i c h

!

' I

p a n e l 3 8

j

5.3.1 T e s t i n g of c o o l l n g e f f e c t s on a a n d u l c h

p"iMI

. .

.

39

,

5.4

.

E x p e r i m e n t r e s u l t s a n a l y s i s

. 4 .

[

5.5 Canparieon'betveen e x p e r i m e n t a l and I

t h e o r < t i s a l r e , s u l t a 5 1 + , /

>

' 1

,

='-

I

.

. -

^{v i i i}

-

,

I _.

.

.

^,

^. 1 . ^.

P a g e

cwm

V. MEMAL~ CREEP MID $RINKAGE EQPECTS I

I

ON CONCRETE SANDWI$ WALL PANELS 5.6

me-I

e x p a n e x o n on connecting p l n a

a n d h e a t loss a t e a r n e r p a n e l d m e t h o d s ,

\ of i m p r o v e m e n t ' 5 3

5.7 O l s c ~ B ~ x o n 5 7

.

CHAPTER V I

.

STRUCWRRT. AHRLISIS Od CoNCTTe

1

SANDWICH PANELS FOR OIFPKRENT CORE

i

^,

' w r e n m s n o

r i c e n l l m n e s s A 5 s

6 . 1 T h e o r y 5 8

-

6.1.1 B e n d i n g and s h e a r stresses 6 2

6.1.2 DeE1eetio.n of a landwlch b e a n 6 6

6.2 T e s t i n g m a t e r i a l . a n d appersitulr 6 7 - 6 . 2 . 1 S m a l l p a n e l w i t h o u t shear c o n n e c t ' o r 6 7 6.2.2 Large p a n e l w i t h s h e a r c o n n e c t o r 6 7

6.2.3 T e s t i n g a p p a r a t u s 7 1

I

i a ~ mad a p p l i c s t ~ o n

h 7 1 (bl D e f l e c t i o n and s t r s 1 n m e a s u r e m e n t 7 4 6.1 E x p e r i m e n t for b e n d i n g and d e f l e c t i o n

t e s t s on s a n d w i c h p a n e l v i t h and v i t h o i t

.

s h e a r c o n n e c t o r 8 3

' 6:3.1 FOI. m a l l p e n e l w i t h o u t shear E o M e c t O r 8 3 6 . 3 . 2 P o r l a r g e p a n e l w i t h shear connsctor

.

8 5

:- ^-1.-

\ . .

' d Page

. %

9

CHEYTER VI

.

STKUCIURRL A V A L Y S I S OF CONCRETE

-

^I\

i

SANDWICH PANELS XIOR DIFFERENT CORE

MATERIALS AUD F E E TWICKNESS

- .

6.4 shear test erpermment on sandwich panel W I C ~ and w i t h o v t shear oonnecwr 90

,

.

6.4 .l Por'spll panel ehear oonnector ,90 ' with shear cbnnsctor 90

6.5 Results a n a l y a ~ e 94

,

I 6.5.1 For the small panel

.

⁹⁴

6.5.2 Por the large panel 98

CHAPTER VII

.

CURING OF CONCRETB SI\NDWICH PANEL* 101

& .

olr*mn vrIr DESIGN OF TYPIW r n N c n m S A N D W ~ C H

PANELS I

.

103

Design considerations

11) me thickness of both faces of

+ panel

12) me loading conairions (3) me iirs Lesistance of sandwich

panels

(41 ' The t e m p e r a t u ~ e gradient between faces

( s i

=he sandrich panel anchor system

CHqPTER V I I I . DESIGN OP pPICAL CONCRETE SANDWICH

' PANELS

8.2

.

~ e s i g n example of a non-composite ,

sandwich p a n e l 109-

Panel s e c t i o n p r o p e r t i e s 109

S t r i p p i n g d e s i g n

,410

S i r i p p i n g i n s e r t

.

110

Handling i n s e r t 111

Wind d e s i g n ' 111

panel a n c h o r system

.

111

Pire r e s i s t a n o e of the sandwich

panel 113

,

Temperature q r a d i e n r between faces

($1 v o l m e change l o a d s 115

(10) O t h e r l a a d c o n d i t i o n s 115 CHAPTER I X . -PPACTICIU. APPLICATION AND COST

EVIU.UATIOII OF COCRETE SANDWICH PANELS 117

CHAPTER X . CONCLUSIONS 119

10..1 ~ d r t h e heacing and c o a l i n g of the

sandwich p a n e l 119.

, ' 10.2 POT the bending, d e f l e c t i o n s and Shear

' REPERENCES

.

122

APPENDIX I. list O f S u p p l i e r s

. ... . .

¹²⁵

.-. . . ^.

LIST OF TABLES Page

, 5.f =re& parameters IC. Winter. 19721

-

, 24 5.2 ~ a i r i m m d e f l e c t i o n s due t o expansion f r a n ,

t e n p e r a t i r e change o f , 20' c t o 33.3' c

. .. .

- b

.

temperature change .of 10'

c

t o -13' c 133O

c

temperature d i f f e r e n t i a l ) " '

.

48 5.4 cowariaon between t h e o r e t i c a l and

exp&-inenaal d e f l e c t i o n s .at ;he c8nter bf.

(

. . . .

t h e t?p concrete l a y e r 52

. ,

,&.I d v e r a g e d i a l gage l i n m i l l i m e t e r s 1 and

. .

s t r a i n gage !I; lo-'] measucenenta f o r

-11 panel 84 '

6.2 Average 'dip1 gage ( i n R i l l i n e t e r ~ l and

.

^atrain gage I 1 x measurementsfor

.

, '

.

.

l a r g e p a n e l '89 '

' 6.3 Comparison of t h e o r e t i c a l and e x p s r l n e n t a l r e s u ~ t s f o r r n y i q m c e n t r a l d e f i e c t i o n

l m i l l i n e r e r e ) f o r s m a l l panel 9 7

.

6.4 m p a r i e o n o f t h e o r e t i c a l anh experimental r e s u l t s f o r

mximum.centri~

d e f l e c t i o n ,

. . . .

( m i l l i r n e t e r a l f q r l a r g e panel

.

97

.

- 0 - : ,

- X i i

-

< .

. . . .

.

.- LIST OP FIGURES

. ^.

^Page

5.1 T h e m e l p r o p e r t i e s

-

h e a t flow u(s11 value

, .

for V ~ T ~ O Y S thickne88 Of 'solid panela made

. .

w i t h noml/ l i g h t w e i g h t . 'foamed concrete

....

.

.

and sandwich panel= ( ~ e a b u , 1959) 1 8 .

. .. . .

,

.'

^5.2

.

Typical aandrich p a n e l s designed f o r a h e a t

. .

. .

^{flow uts11} v a l u e or 0.852, a c t u a l +actors as

..:

. .

1

' '

. .

a f f e c t e d by rib's (Leabu, 19591 ' ' 19

. .

5.3 Typical oreep a w e f o r concrete loaded t o

- .

4 MPa a t age 28 days ( G . wlplter, 19121 23 5 . 4 .-peratwe g r a d i e n t

ChrougJ

^{f0u:type. of}

p z e c a s t w a l l panel

.

(leabu, 19591 . 26 5.5 H e a t f l o v "(ST1 UIrOvgh t y p i c a l w a l l section

-7-

(T. C o l l i n s , 1954) 3 1

5.6 H o r i z o n t a l displaoement due t o temperature

, - '

d i f f e r e n t l a 1 ~ l s a b u . 19591 33

5.1 L a t e r a l d e f l e c t x o n veraus span l e n g t h f o r a t y p i c a l 130 m sandwich panel (Leah". 1959) 37 5.8 ~ l e v a t i o b shoving experimental s e t - u p ' . 41 ,

.

! ' 5.9 , P l a n for l a y o u t of d i a l g a g e s (N.T.S.1 42

.

1.10 E l e v a t i o n shoving d i a l gages l o c a t i o n (N.F.S.1 42

. .

_Page

5.11 ' m f o m e d shaoe of sandwich Dane1 a f t e r warm temperatui-e d i f f e ; e n t i a l of 13.P

c

49

1

:

.'

^{5.12 '} Deformed shap,e of dandwich p q n s l ' s f t e r m l d

- ^{, .} _.

tsmpararuce d i f f e r e n t i a l of 3s0

c

so

Sandwich panel coke; d e t a i l s , 55

Dimensions Of thE sandwich heam o f equal

f a c e t h i o k n e s s 59

Sign conventions

h

⁶⁰

~ i a e n s l o n s of t h e sandwich beam o f unequal I

faoe t h i d n e s a 65

Plan ror l a y o a t of s h e a r connector pins' and d e t a i l s f o r sandwich p a n e l anchor system 69 Sandwich p a n e l a n c h o r i n g , s y ~ t e m , S e c t i o n C-C

.

70

I P l a n f o r l a y o u t O f loading frame for m a l l

-

p a n e l without shear connector 7 s

.

. .

laad d i s t r i b u t i o n syarsn f o r sda11 panel.

S e c t i o n &-A 76

.

i

r:)

. :

D i a l and s t r a i n gage i a y o u t f o r m a l l panel ' ' 72 ^' Plan f o r l a y o u t of l o a d i frame for l a r g e

. -

[

panel w i t h

. .

7 8

, . .

. I -

-

xi"

- .

Page 6.10 m a d distribution system for large panel.

Section 8-8 79

6.11 -1 and strain gage layout foe large panel 80 6.12 m x i n u n sentral deflection for smll'.panel 95

.

6.13 M a x i n m central deflection for large panel 9 6 8.1 Design example of a non-Eemposite sandwich

.

. ppnel -

. :

¹¹²

:, .

.

,

.

. .

^{. ,}

.

- 8.2 Typical nonlmneorite sandwish panel I ,

installation details 116

,

.

-

xv

- . . . ' . ' . ,

' $ .

. -

^{. - , i:}

.

LIST OF'PWLTES ,

.

_{pa& ,}

.

5.1- l a y o u t of heating c o i l on t o p of panel 43 . : % w r q t u r e indioator f o r c h e ~ k i n g tsmeraturs

on the s m f a c e of top laye: of concrete. 4 3 Layout of c a r l l n g coils f o r providing s o l d

. .

temperature up &'a maximum o f . l o O F 1-13O

.

C) . ,45

. .

^.

.

ALr mmpressar m o l i n q assembly fot providing , ' cold temperature t~ a mximun of 10- I

I-13O C l 45

. .

oenera1 view of small pane1 set "p f a r

bending aind d e f l e c t i o n t e s t ' 72

and b a l l bearings 81

. .

6.3 view of underside of a n a l l panel shoving '

-

i

,

.

, l a y o o t of bo~tttom d i a l gages,and s t r a i n gages J2 ,

. . .

. I

. .

6.4 View of cracking a t lower concrete face and

. .

band shear f a i l u r e a t core f o r a n a l l panel 86

,

6.5 General viev of l a m e pane1 s e t up f o r

bending and de€le.otion t e s t 87

.

. .

,

. .

*-

^{x v i}

-

Page 6.6 Vier of cracking at lover concrete face

and lover bond failure at core for large panal 88

1

h

-

6 . 7 General view o f small panel a s t up for

1

ehear t e s t 9 1

!

^{6.8 View of} after shear ^core t e s t failure for m a l l panel

. ^.

92

3 .

i

A -

^6.9 General view of large panel s e t up for

!

shear t e s t

sa

I ⁱ

I

I \

-C

1

I I

I

^I

^I

I

\

/

' --- --

&

CHAPTER I I m O D U C T I O N

By d e f i n i t i o n , a concrete sandwich panel c o n ~ i r i t s of two face. of high s t r e n g t h , high d e n a i t y concrete bonded tb a core of r e l a t i v e l y 10%" d e n s i t y i n s u l a t i o n m a t e r i a l .

The primary o b j e c t i v e of t h i e t h e s i s i s ^to provide background i n f o m a t i o n and asseae c u r r e n t procedures i n t h e s t r u c t u r a l design and d n a l y s i a of concrete sandwich panels. I n addirron;

the t h e s i s i s prepared M provide information which w a l requested by a l o c a l c o n c m t e s u p p l ~ e r . To achieve t h i s . an extensive l i t e r a t u r e asarch and sxpllrinental i n v a m t i g a t i o n ~ ,

"U perfamed.

/

The p r e s e n t a t i o n of Me t h e s i s is o u t l i n e d a. follow.:

Chapter I i s an i n t r o d u s t i o n . ,

Chapter 11 d e s c r i b e s the h i s t o r y or sandwich panel concepts, the%= gradual d e v s l m s n t and i n p r o v s n e n r ~ up to toda".

Chapter TI1 d e s c r i b a s the t y p ~ of c o n c r e t e ~ a n d v i c h wall

.

p a n e l s , t h e i r c h a r a c t e r i s t i c s and functions.

'

Chapter lv , d e s c r i b e s some or the problerne encountered by the

engineer, a r c h i t e c t o r Eontractor during f a b r i c a t i o n , conatruation and performance stagae.

Chapter V deaoribes t h s e f f e c t s of t h e m a l , shrinkage and ¹ c r e e p on odnsrete sandwich panels. An experiment

.

s=

i s c a r r i e d o u t on h e a t i n g and cooling of a sandwich

1

Chapter VI o u t l i n e s the theory of ordinary sanhri& b..n behavior t h a t i s applicable f o r Me a n a l y s i s of the concrete sandwich panela. An experiment

?

to detennine'the behavior of t h e bvo panels,

; i

with and without ahear connector^.

i Chapter VII pramants b a s i s -nts on an effective way of

i :

ouri11g concrste sandwich panels.

L .

Chapter VTlI d s s c r i b e s i n d e t a i l t h e d e s i g n considerations' f o r

i

ooncrete sandwich panels and a design e x m p l e of I

r

a non-canposits sapdwich,pmel f o r e r p e r i w n t a l

t e s t i n g . 'L

'

Chapter IX describe. sonre of t h e p r a c t i c a l applications of

" '

^concrete ~landwioh panels and the cost of

f a b r i c a t i n g such panela.

I

I

^{Chapter X} containa the70ncluding e x p e r h n t a l result. and

I

remarks rasearch based findings on t h e far

concrate sandvish panel..

i

1 I

.,

I

.

The prrncip1e of the s t r u c t u r a l sandwich pane1 i s not a new invention h u t s m p l y a r s e p p l i c a r r o n of concepts usad

Althauqh concrete sandwich panel d e s i g n 18 considered I

'

~ I a ' t i ~ I y new to the C o n S Y I t i o n i n d u s t w , -re 1. evidence

I

Tnveatrgations i n t o the h i s t o r y of sandwich panela have

1

use the p r t n c i p l e i n 1819 i n axpenmenting with bridge design

I

using laminated wood deckihg and concrete as a c o o l ~ s i t e beam.

Besides concrete sandwich panels, t h e r e are many other t y p e s

i

^af sandwich p a n e l s u t i l r z x n g d i f f e r e n t core and face m a t e r i a l s . The three mrn typelr are:

I

I

¹¹¹ S o l i d core: w i n g m a t e r i a l s such as b a l s a mod, f i b r e I board, foamed g l a s s and expanded p l a a t l c s .

121 Roneycanb cora: using three main f i a t e t x a l s such as metals, p l a s t i c s and resin-imhrognated paper. Usually t h i s honeyo& e f f e c t takes t h e form o f p a r t i t i o n i n g ' a t r i g h t a n g l e s to the faces.

131 Corrugated oore: t h e material. used i n t h i s form are

1

-

s r m l l a r t o t h e honeyoorb aorsa. The corrugations oreate

t h e form of p a r t i t i o n i n g a t an i n c l i n e d angle to t h e panel f a c e s , and run alohq the id1 langth'of thp pansl.

In 1906. t h e possIbi1itis. of con.trusting concrete aandwich panels were of g r e a t 1ntera.t to engineers and contractors i n t h e urvtad s t a t e s . rn t h a t year, a building

was m n s t r u o t e d with aanduich t i l t - u p panels. S m e of Ule

.-

⁴

-

^.

, i

w a l l s were hollow, made by c a s t i n g a 50 m l a y e r of conoreke,

- ^i%

Men a 50 m l a y e r o f sand with a f i n a l 50 rn l a y e r of

concrete. The two o u t e r l a y e r s of o o n c r ~ t a were t i e d together

'

with reanforcing U e s . The sand between t h e two outer faces of concrete was uaehed out with r a t e r as t h e wall was l i f t e d .

I n 1930, t h e ssnhlich panel used by the building industry was t h e cement aabestoe hoard, which had cement asbestos faces bonded t o a f i b r e board.

I n 1933, Swedish b u i l d e r s made a aandrrch wall of 125 m 1 l g h N e r g h t concrete block, which was c a s t and bondah to dense i n - a l t e concrete. A 15 m t h i c k l i n e cement mortar was Ulen p l a r t e r e a on m c o u t s i d e of t h e lightweight concrete block.

I n 1952, the designers i n t h e United S t a t e s developed a I mineraliasd wood 0h.p eandwioh pansl. Esch cladding panel

.,

^{was crnpozed of M O ootar} faoes of n o m a l ooncrete 45 ran thxck U

reinforced with rrrs mesh. Lightweight precast inanlation

I ,

vam 40 m thick uaing chemically n i n e r a l i a e d m o d c h i p s as an aggregate. The ho outer faces were connestad through the i n s u l a t i o n by s h e a r t i e s i n order t o t r a n s f e r h o r i z o n t a l

s h e a r £ran one f a c e to t h e o t h e r . s i n c e t h e n c o n c r e t e

.

sandwich p a n s l s have been developed u s i n g d i f f e r e n t i n e u l a t i n g 0 m a t e r i a l s . r d e a l l y , such i n s u l a t i n g m a t e r i a l s should possess q u a l i t l e a su&as: low denarty, r e l a t i v e l y high compressive s t r e n g t h , high &ear s t r e n g t h , good bonding c h a r s c t e r l s t l c s ,

polystyrene. Ccwpreseed wood f i b r e s I" cement, f a d c o n c r e t e . Styrofoam and polyurethane.

1n t h e l a m 1970's. t h e r e were many p r e c a s t concrete sandwich p a n e l s f a b r l s a t e d throughout t h e Unrted States and Canada.

The no.* cCmmn1y used type of sandwich pans1 c o n s r s t e o f

/

an i n n e r face ( 1 , s . t h e load b e a r i n g p a n e l l , a l a y e r of r i g i d thermal ~ n s u l a n o n and an a r c h i t e c t u r a l Dater face. '

1n t h e u n i r s a S t a e a s . t h e Burke company from San n e t e o , c a l i f o r n i s bas developed c o n c r e t e sanduich+panels w i t h a

,

s p e c i a l anchor aysten. p h i s Burke p a y 1 anchor systen, o o n s i s t s

7 of a p a n e l anchor, torsion anchor, and'hociznntal t i e s . his system connects t h e outer f a c e and t h e load b e a r i n g f a c e

.

,

- ,

t o g e t h e r to

rehat

t h e v e r t i c a l , .horl.onral and e c c e n t r i c loads.

~n c e n t r a l mnada, s u p e r i o r concrete o f exd dale, O n t a r i o

. .

. . .

( o r i g i n a t i n g from u ~ a u t o n , Texas1 has a1.o developed s i m i l a r

.

' coricrek sandwich p a n e l s ~ i.a s l e e v e anchor systsm. i

I n A t l a n t i c Canads, S t r e a c o n l t d . of S a i n t Job", Nar '

,I ^'.

~ r u n s w i c k , h a s developed s new t y p o f concrete s a d w i o h panel.

I

mi.

p a n e l , r h l c h is conposed,of Oro prestressed concrete

- 6 -

E ^*

fasea xi* a continuous la& of insulation In between them, i s m dCorewall.

! i ,

1n addition, ~ t l a n t i i concrete LN. of st. ~ohn's.

I

Neufourdland i s m n s i d e r i w developing some new types of concrete sandwich panels. I t i s partly for .these reasons

i

^that experiments are being conducted fak thii p r o j e c t . ' Due to the nore advanced techniques i n designing concrete sandwich panels, production d o s e have been s u b s t a n t i a l l y

!

widely usad wan before.

, , . - .

. . .

...

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.

, . ,

.

. . .

TYPES OF CONCFZTE SANDWICH WALL PANELS . :

.

. . .

i . .

. . . . .

.. -

.

. . ^. . . _{. . . .} .

A precaat'concrete'eand~ich panel c o m i s e s of two f a c e s

. . . . .

. . . ^. . .

, of r e l a t i y e l y t h i n , i i q h ' d e n s i t y and high stre'ngth: concrete, '

.

-

. .

bondsd t b a core of ;;lstiv&ly f i g i d

. . \

The f u n c t i o n of the c o r e m a t e r i a l i s t o s + ~ i i i ' z e the r e l a t i v e l y

..

\

^':

. . . . .

. t h i n r a c e s o P h i 9 h stf:&th concyete, and'& proviae a. high

...I.

s t i f f n e s s f a c t o r .fo; +e.:conbination

df

n i i & r i i i s by.&paratin< ," ,

. . . .

,-

the faces. m i a conbination prodloes'a l i g t i t e r , strange? _{- ,}

. . .

^-~

w a l l and .if the tors m a t e r i a l

i L

a ~ g o e . i n s h l ; t o r , i t producea

8

-.

.

..- a b e t t e r -ineuldted wall.

' - . ,".,

. & ,

Prom the *age y d a p b l i c 8 t i o n pointa of.view, t h e r e ark

t w . t y p a s of concrete sandwich pansls,.n&eiy: ,;. ' '

,

:

(11 a r o h i t e c t u r a l panels, and

..

^{( ,} .

.

^{' - .}

.

' 0

( 2 ) l o a d bearing panels.

. .

..., . .

3.1 A r c h i t e c t u r a l panels

..

A r c h i t e c t u r a l sandwich wall panels are " o n - m p o a i t e panels

. .

.'

^.

^{. .}

in.'which bb* f a c e s p a r t i c i p a t e i n t r a n s f e r r i n g .the l a t e r a l

l o a b to th; h o r i k o n t a i s t r u c t u r a l s t e e l or r e i n f o r c e d eoncrate

.

^;

. . .

' framework. For thi: b u i l d i n g f f a m e ~ r k with p r e c e e t concrete

.

.

' aandwf<hip+els, t h e $ r e c a s t u n i t s are.int+nded f o r building .

.

:. e n c l ~ s u r e only, and other.desiqn loads ere r o t a l l y s u p p r t e d

.

'

.

.

....

. by t h e s t r u c t u r a l frame t d f o m a canplex s t r u c t u r a l system.

me outer face o f t h e panel i s c ~ n n e c t e d t o t h e other f a c e

.

, by relafively. f l s x i b q t i e s , a i l w i n g d i f f e r e n t i a l mwemente 'of 1

. . .

.

, .

. . , _{. - ..} . . .

. . . . ; .

- ^{. .} . .

^%

I

-

the f a s e s , with changing temperatures and h u m i d i t y . c o n d i t i o n a .

.

^. T h i s type of sandwioh h n e l i s n o r commonly used because the

-

structural p r o p e r t i e s oi t h e c o n c r e t e ' a r e nor f u l l y u t i l i z e d , and t h e t e f o r e c o n s i d e r e d to b e n o t economically v i a b l e .

, . . .

^P

3.2 Load b e a r i n g lianels. .

Load b e a r i n * sa?dvich w a l l paneln.cdn be composite o r . '

.

, "On-solaposite.

.(

. .

^{l a )} mm~.site p a n e l s are p.nels vhioh have s t i f f e r

.

.mnnection; between M e i n n e r and o u t e r faces so t h a t the. two fadsb w i l l a c t j o i n t l y i \ r e s i a t i n g loads. T h i s p e r m i t s a .Z n e t r e d u c t i o n i n the o v e r a l l wall t h i c k n e s s . Also, depending

' on the r i g i d i t y o f t h e connector system, i n t e r a c t i o n between

. .

.

^{, the facer may} b e t o t a l or p a r t i a l . me ~ q p o s i t e p a n e l w i l l

. . .

o f t e n be s u b j e c t e d t o b a r i n g d v r i n g s e r v i c e . me l a r g e

-

tempeqature changes between f a c e s w i l l t e n d l o bow t h e paflel

~ ( p

,

.

inwards. zhe .ideas of p r e s h r e a s i n g bAth faces o f . = composite

<.

p m e l a r e t o h k l p c o u n t e r a c t thermal bowing, and to improve m e behdvior OF t h e members by:oreating uniform co;pression i n both f a c P .

ibl. N o n - o o m ~ s i t e panela are p a n e l s which have t h e

,

i n n e r f a c e ( s t r u c t u r a l f a c e ) transfer t h e l a t e r a l l o a d s t o

. .

t h e , h o t i z o n t a l s t r u c t u r a l framework and support M e w e i g h t , of the o u t e i face ~ n a n - s t r u c t u r a l f a c e ) . NO"-compdsite panela

can be designed i n a way t h a t one face can move w i t h o u t a f f e c t i n g t h e o t h e r . The minimum thicknesa o f t h e f a c e s i g dependent' ,---'

. . .

I

,

:

upon strvct"ra1

1

r e q u i r m n t s , reinforcelnent cover, and

i

^handling consiairahons. ~on-smp&ite p a n s ~ i are more

c-only used, du( to those p o t s n t i d ~ performance p r o b l e b i

. - .

- 1

1

as.oct.ted v i m ~ r n ~ o . i b p a n e l s , such as M e bowing e f f e c t . ,

.

A ! '

. L due k.3 tempsiatvre v a r i a t i o n s beWeen the concrete faces, .

.

!

and the d i s t r i b u t i o n e f f e c t s o f the e o c e n t r i c loads on c m p o s i t e panels.

.

< . z -

. .

\

- 1 0 -

CHAPTER _PROBLMS IY _{A M I} PERPOPMANU: OF CONCRETE

.

SANMIICH PANELS

. . ^. .

The probl-f which a r c h i t e c t s , engineers and d o n t r a s r o r a

'

g e n e r a l l y encounter with' s a n d w i c h - p n e l s d u r i n g f a b r i c a t i o n , c o n s < r u c t i o n a n q p r f o m a n c e a t a g e s a r e described as follows:

.

,

. .

' - - 4.1 Bonding b e m e n concrete and ' i n a n l a t i a n

*

A c o n c r e t e asndwich p a n e l when loaded, d e v e l o p s ahear stresses

:. .,

^{a t both} i n t e r f a c s s o f the c o r e a k d the fasss. If M e p a n e l i s not c o n n e c t e d w i t h , a p r o p e r shear s o n n s o t o r , M e r e rill be

. . . . , a bond ahear f e i l v r e between the core a n d t h e faces. From the ahear teat o" Me concr'ete sandwich pane~:specimenn condvcted by 0 . s i n q h a n d J. C l a y t o n ( I & ) , M e study i n d i c a t e d t h a t

.

I .

t h e . s h e a r f a i l u r e i n a l l M e , ; p c i n e n s v i a at the i n t e r f a c e I I '

between t h e c o r e add the f i r s t l a y e r o f concrete c a s t e d d u r i n g ' fabr{cation. I n the sane e x p r h e n t , i n o r d e r to a c h i e v e bond '

, .

./

s t r e s s between the core ,and both f a c e s , dome cell. from both eid.6 Of the COTe SYTf2.Ce WeTB N t O u t - tO f O m n f c r o h o l e s a n d porespaces. 'The o b j e c t i v e of t h i s w s s t o p e r m i t fresh

. . .

c o n c r e t e f l w i n g i n t o the i i c m h o l e s a n d porespaces i n o r d e r

.

, ,

- to produce r e l i a b l e bonds o f e q u a l s t r e n g t h a t b o t h i n t e r f a c e s . To a c h i e v e t h i s , t h m 00.e was l a i d I n a h o r i z o n t a l p o s i t i o n

, to r e c e i v e the .fresh c o n c r e t e bn i t s ~ u r f a c e ' t o f othe ~ , .

.

f i r s t f a c e . T h i ~ f a c e i a s v i b r a t e d ' t o c o n s o l i d a t e t h e c o n c r e t e

' a n d f a r c e d the f i n e r p a t t i c l e a i n t o t h e 'microholes and p o r e s p c ; s . '

.

a t the a u r f a F e of the &re. L f t e r curing; the p a n e l was

.

.

: ^.j

I

i n v e r t e d to receive M e next c o n c r e t e f a c i n g i n ' t h e same manner. Althrmsh'the' above proceaa of f a b r i c a t i n g sandwich p a n e l a c o u l d develop r e l i a b l e bands between the core and the faces, i t was not c o n s r d e r e d p r a c t i c a l and e c a n m i s a l . because it was t i m conavming and l a b o u r i n t e n s i v e .

new anchor systems hsus bqen developed f o r j o i n i n g M ~

-

~^' ~ ~ l

'

faces through s e v e r a l m i l l i m e t e r s o f i n s u l a t i o n , v h i c h v i l l m i n i i i z e bond f a l u r e between the c o r e a n d the

f

concrete

_.

€ a c e s .

, .1 4.2 J o i n t s in panel

Most, s ~ n c r e t e farma t e n d to p r o d u c e l a r g e r element8 when .

-

i ' ,they are re-used. T h i s i s d u e

td

t h e c o n c r e t e pressures

.

o i e a t e d by the c o n t i n u o u s v i b r a t i o n s of Me form bed a t ea

.L1

' pour. For this r e a s o n , i t i s very d i f f i c u l t t o produce t h e concrete p a n e l s w i t h i n i t s s m a l l a l l o w a b l e B e v i a t i o n s

.

Hence t h e d i b s i o n r l s t a b i l i t y and the spareness o f e e fornnmrk should be p r o p e r l y c o n t r o l l e d . a n d re-checked in every concrete pour, so as to minimize the p a s i b l e c l o s e - i n pmblena

8 .

d u r i n g e r e c t i o n .

. .

I

^{: r}

me w e a t h e r t i g h t n e s n of a h o r i z o n t a l , v e r t i c a l or corner j o i n t i s v e r y inportant. IF t h e j o i n t is not d e s i g n a d or

.

. c o n s t r u c t e d properly, M e r e v i l l b e leakage due t o w i n d prpresaure, ^{" '} d r i v i n g rai; and water r u n n i n g d w n the w a l l .

I

c a u s i n g w i t h

a j o i n t s e a l i n g 'conpound and a l w abaexption backing rope i a

. .

the mostleonnnon p r a c t i c e aE t r e a t i n g a j o i n t between concrete

,

j .

., W~IF ^{i m}

^{cw "th the b - ~}" " d ~ i f i

I

' ' 1 .

. - .

..

, .,

J -

.- . , ,

. .

.

-

^{. . -}

. <

l a y e r s , s t a i n l e s s a t e e l anchor s y e t e n ~ a n d .hear ties have been developed, and p r o m r c o n ~ u u c t i o n t e c h n i q u e s w i l l v e n r l l a t e t h e i n s u l a t i n g l a y e r s .

m

a v o i d e x c e r e i v e cracking, c o n t r o l j o i n t s s h o u l d be , , provided i n l a r g e p a n e l l to d i v i d e fhe outer face i n t o u n i t q . The p a t t e r n ' f o r such c o n t r o l j o i n t s becomes an i w r t a n t a r c h i t e a a u r a l f e a t u r e a n d a l i g n i n g such j o i n t s w i l adjasent .panels m a i n s a mjor d e s i g n c e n s i d e r l r i o n f o r s u c c e s s f u l

--' .

prformhnce. -i , ,

. ^. . . . . .

6 . 3 Pam1 connections.

Pe conn<ctlons f 6 r the u a n s a r i 8 s i o n of shear, a x i a l l o a d , moments and torsions from ;ember to d e r or n&er t o

. .

supporting structure a r e very i m p r t a n t i n sandwich panelb.

The c o n n e c t i o n s i n I w d b e a r i n g panels d i r e c t l y a f f e d t the

-.

structural' i n t e g r i t y of the b u i l d i n g s t r u c t u r e a n d t h e i r d e s i g n .

.

must b e a d e q u q b for the f v n c t l o n s i n t e n d e d .

Crack~ng o f welded con./ections on p r e c a s t concrete u n i t s i i s c r e a t i n g p m b l e n s f o r me L r e c a s t industcy. mese connections

.

^'

may

onbis't

of a ' w e l e d j o i n t between e t e e l . a n s l e s , . c h r n n e l e or p l a t e s . s i n c e t h e m l a r e r s a t r a i n t e d e v e l o ~ e d

7

o n the c o n n e c t i o n s a g a i n s t t h e r n s l c o n t r a c t i o n s a n d o t h e r d e f o n i a t i o n r o c c u r i n g through* a nuucturs, which have a p p r s c i a b l e e x t e s t a on' ^'

.

1

^*e damqge t o c o n n e c t i o n s , or t o the panel ' i t s e l f

.'

B o l t e d ,

. ,

\onneDtidns with o v e r s i z e d a l o t a on . a n q ~ e a and p l a t e ; have .' been c o m a n l y used to a l l m f l e x i b i l J t y o n d i f f e r e i r t i a l

. .- .

lnovenents of connectlona.

.

,

.

-

¹³

- I

4:4 C o n t r o l vf s r a o k i n q

v

c o n t r o l of c r b e k i n g becomes as i m p o r t a n t as c o n t r o l of d e f l e c t i o n i n r e i n f o r c e d concrete s t r u c t u r e s as w e l l as eandvlch panela. m s t cracks are a r e s u l t of the i o l l n r h r g a c t i o n s t o which m n c r e G c a n b e nubjccted to:

.

¹

l a ) v o l v m e t r i c change ,

.

'

l i i Drying s h r i n k a g e '

. . .

( i i l Crew under, e u s t a i n s d l o a d -

l l i i l Thermal s t r e s s e s i n c l u d i n g e l e v a t e d temperatures.

he

above l i l

.

^{l i i l}

^,

and ( i w ) i a c t o r a rill b e d e s c r i b e d more thoroughly in Chapter

v

of1 t h i s thesis.

l b l D z r e s t 'stresrr due t o a p p l i e d l o a d 8 o r reattion.,

-

o r i n t e r n a l etre.8 d u e t o c o e t i n u i t y . long t e r n

1

d e f l e c t i o n o r e n v i r o m n t a l e f f e c t s r n c l v d r l ~ g d l f f s r e n t i a l m v e a e n t I" a t r v c t u r a 1 s y s m s . l'bl F l e x u r a l a t r e s a due k o bending.

i i l e t h e n e t r e s u l t of the& three a c t i o n s i a the f o ~ m a t i o n of cracks, the mechanisms o f t h e i r developnent c a n n o t be c o n s i d e r e d i d e n t i c a l . american c o n c r e t e I n s t i t u t e c o m m i t t e e , ' 224, s p e c i a l l y formed t o i n v e s t i g a t e Ma prohlema o f concrete

- ²

c e a c k l n g , hae Uls r e s p o n a r b i l i t y of c o a r e l a t i w a l l t h e

a v a i l a b l e i n f o m a t i a n f o r the purpose of e s t a h l i e h i n g a c s u r a t e

. .

, ,

)

recommended

practices

on crack c o n t r o l ' i n any concrete s z a c t u r e s

1

I .

. ,

L

1

I n a form satisfactory for use by the deargrrrs, engineers and contractors. such emprehenslve remnan.ndations are

slimmate the drawbacks in the performance of the precast concrete systems.

-

^{1 5}

-

THE%, CREEP MJD SHRIlarcE WPECTS ON CONCRETE SANDWICR

w PANELS

I _5.1 General

I

^me e v o ~ u i b n df concrete sandwich p a n e l a is gaming p o p l a r i t y In the b u i l d r n g induskry.

me

moer troublesome pmblema e n c o u n t e r d w i t h sandwiqh p a n e l s :re sumarrzed m

I

Section 5.1.1 and 5.1.2.

A cancrete sandwich wall panel may b e subjes&d aimultanedusly to:

1

..

.

-la1

'

d r y i n g lahrinkage) and c w l i n g Icontraction1

.

lbl d r y i n g Ishrinkage) and h e a t i n g Iarpilnaion),

.

,

' I ' (91 w e t t i n g lawelling) and c o a l i n g . l s o n t r a c t i o n l , or

Id1 v e t t i n g lswslling) and h e a t i n g (expansion)

.

m e b a s i c oauee of a l a r g e m a j o r i t y o f f e i l u r e a ' i s ' d u e t o i M d e T a t s prov%aion f o r the e f f e c t s of c r e e p , shrinkage

and tsmpsrature changes.

. .

A cmnbiniltion of changes i n temperature and humidity can create more Bevsre c o n d i t i o n s than ~e normal d e s i g n r e s u i r a e n t s . Bxsessive stresses and def1esUo"s w i l l a l s o be caused by the c m b l n e d s f f e c t a of ,creep, shrinkage and'

temperature & h a v e s .

'';

\,

i

5.1.1 Maintaining a design f a c t o r of h e a t transmission UISII v a l u e

. .

Ths uiS11 value o f any w a l l o r rdof m a t e r i a l i s ilnportant

. .

i n the design of b u i l d i n g s . I t i n d i c a t e s how much heat i n , w a t t s passea through a square metre of any g i v e n m a t e r i a l i n . 1 how f o r e a c h degree d i f f e r e n c e i n . t e m p a r a t u r = (Centigrade)

,

^'

between the e x t e r i o r and i n t e r i o r f a q e s .

. , ec' .

.+

me e t i e s t i v e n s s s OF a b u i l d i n g assembly a u c h ' a a a ^'

8 w a l l o r roof i n r s s i a t i n g the flow 'of h e a t under s t a t i c c o n d i t i o n s i s d e f i n e d as its t h e m a l resistance o r Risil value.. me h e a t l o i s UiSIl i s i n v e r s e l y p r o p o r t i o n a l to t h e m a l res,btance, i t i s t h e r e f o r e p o s s i b l e ta i n d i c a r s . , MI, r e l a t i v heat: l o s s p o t e n t i a l s of t h e s e w a l l s by the

..

1.

r e c i p r o c a l s of t h e i r RISII values.

Pigure 5.1 g i v e s t h e i e l a t i v e UISII v a l u e s of t h e ' d i f f e r e n t t y p e s of s o l i d normal, l i g h h r e l g h t and foamed concrete panals t o g e t k r w i t h sandwich Panels f o r s e v e r a l panel

. .

thickpaasen. - ~ i s u l a t e d sandwich panel? are u s u a l l y d k i g n e d with a U I S I I r a n g i n g from 0.852 t o 1.136 ~ / m ~ . h r . ~ c . me.

e f f e c t of r i b s and s o l i d s e c t i o n s i n the p a n e l i s eeldam;

cone>dered. This e f f e c t , however, i s g r e a t enbvgh ta i n c r e a s e t h e UISTI value? of t h e panel aa much as 50 p e r c e n t . ,

IRabu, V.F. (19591 indioated t h a t r i b s and s o l i d - '

concrete s e c t i o n s of a sandwioh panel using a h i g h l y e f f i c i e n t ' i n s u l a t i ~ n c ~ r e reduce t h e i r inemlation q v a l i t i e d considerably,

4

s o l i d Imncrsre e e c t ~ o n s . To illustrate Mi. e f f e c t . some

/

v a I ~ , n f 0.851 are shown i n P i w e 5 . 2 . T h e O a l m l a t i o n of

1 Uli~ valve i s based on the i n s u l a t e d p o r t i o n only. he _.I. a c t u a l valve f o r the over-all panel i m c l u d i n g ribs, eta.)

.

snow a f a c t o r

rron

1.48 to 1.91. mi. z s p r s s m t s an i n a r e a s s ot over 50 p e r c e n t . m e r a t i o of rib area to the i n s u l a t e d . area o f panel ham a cbnsiderable e f f e c t on the U(SI1 value.

, A higher persentage of ^rib area w i l l i n c r e a s e M e heat l o s s cansiderably. where possible, ribs and s o l i d conoreta

/

e t i f f e n e r e should b e k e p t to a minimum or r l i a i ~ t a d i f L-

.

, .

s t i u c t u r a l design m n d i t i o n a p m i t .

.

^.

PANEL THICKNESS (mm)

Fiq 5.1 - ^Thsnnal I ^{1 propaties} - heat flow

U(SI) v o b w for wrroua thakn-8 of sol~d panels

mads with norrnol. I~ghtwe~qM, foamed Concrete

and aandwieh panals. (Laabu, 19591

,

,

.

.

'5.1.2 Bulging ^{. i}

- . . .

~ u l g i n g i n < v e r y cornon p h e m e n o n i n meny p r e c a s t

: 1

oomcrete p ? l s a n d e s p e c i a l l y in theIrdwiCh t y p o f panels..

''

B u l g i w a n d warping

. .

of p r e c a s t s a n d u i d h p a n e l s can

r e s u l ; i n u n s i g h t l y c r a c k s a t the c e i l i n g , f l d o r and p d r t i t i o n s ,

.

'

r .

' i n l e a s p m p e r p r o v i s i m i s made i n the d e s i g n Of p a n e 1 and

?.

c o n n e c t i n g companents. Bulging n a y be EaUsed b y t e m p e r a t u r e . n o i e t u r e , c u r i n g a d s h r i n k a g e d i f f e r e n c e s between t h e i n t e r i o r . and e x t e r i o r f a c e s . m e i r effects on sandwich p a n e l s are 2

d e s c r i b e d i n S e c t i o n 5 . 2 . -. .

. ^.

,

.

wnsion/com;ression t i e s , knoA as the s h e a r connectors,

.

.

, .,

are c m o n l y u s e d ' t p r m i d e enough r e s i s t 2 n c e t o t e m p e r a t u r e

P

^.

^.

. .

,- . .

.

and shri&age a t r e a s . S i m p l e t i e r d a o r bent b a r s are also

..-/-

A s l e e v e a n c h o r hay be u s e d t o c o n n e < t ,Me concrete

faces. men i t i s i n s t a l l e d t o g e w e r w i t h

$

a n c h o r rods,

.'

i t w i l l b e able t o carry a l l the a p p l i e d s h e a r l o a d from _, . . any d i r e c t i o n .

ore i n i o r n a r i o n and d e t a i l s on , s h e a r c o n n e c t o r are

.

.

. '

presented at sect'ibn 5 . 6 .

./--y---

5 . 2 E f f e c t s o f c r e e p , eh;inlsge and t e m m r a t u r e c h a n q e s

. .

.

o n c o n c r e t e sandwich P a n e l s

- T h e d e s i g n far t h e m a 1 and shrinAage s t r e s s e s i s

M~

\

. .

most neglected p a r t o f

.

*day's . d e s i g n p r a c t i c e .

m

a n a l y t i c a l

- _.

_,

.

.

!

. ... .

.

. . . .

- > I - .

, .

: .

I . . . .

.

^{: \}

. .

*

<

,

. _{> . .}

. .

. .

s t u d y few concrete s u v c t v r e s shyer% that severe s u e s s s s '

.

. .

w e r e s e t q:by ' t h e r m a l c h a n g e s . B a s e d on such c o n d i t i o n s ,

. . .

. ,

a l l r o t a t i o n s , movemenrs snd E o i f e e i n c l u d i n g those a n t i c i p a t e d

.

' as a conaeqveme of creep,, s h r i l l l a q e a@ t e m p e r a t u r e ch$nqea

.

I ^-

^' s h o u l d he c o n a i d s r d d

ii

^{M e} d e s i b n of pr&ast romcr~*.

I

.

.

. d e f o r m a t i o n may 66 d i v i d e d i n t o tuo p a r t s : I11 An i n s t a n t a n e o u s d e f o r m a t i o n eingt which occurs

h e d i a t e l y , end a.9.

a n d c o n t i n u e s f o r a l o n g e r t e r m .

I .

^age 18 days w i a r e ~ u ~ t i n g i n s t a n t s n e o u s s t r a i n einat. me b a d .

1

^{: was} then maintained for 2 3 0 d a y s . d u r i n g w h i c h t i m e , - c r e e p

-

- *,

d e f o m a t i e n eOIeep h a d been i n c i e i l s e d U, a l m o s t 3 t i m s . i t r

I ' ^:

instant.neous value: If Me l o a d was m a i n t a i n e d , t h e d e f o r n a t i o n

. .

>

^I

of mncrete would follow the, solid

Bur...

c r ~ e p would

.

p~oceed

.

at a decreaiing rate and ceased at

. .

a final value after

, .

^{' 2 to 5 years.} ' m i s value would depend on the concrete strength _,

. .

, '~ and 0,ther envirormental factors. If Me load was removed after 230 days, the deformason of concr'ere would fo~l?w the unloading dashed curve.. When the concrete was' reloaded at sane later date,'instantaneous and creep defornaiions would

.

. develop again as shown in the reloading dashed curve.

.

.

_{At any} given stress, high-strength concrete shows less ceesp'than low-strdngth concrete as Shawn in Table 5.1.

.:

^{1 ,} ~f eireep is k e final value. of the creep strain, and is the initial, instantaneous strain.Ithe creep coefficient

'

i

Co = eLreep/ einste and the specific creep is e'cre;p pet ma. '.

.

,

. ~

. .

.-

,

. ^'

.

,

.

ⁱ

. . ,

,

.

.

-

I .

\

4e. d l .

.r

1 Figure 5.3-Typical creep curve fn

concrete loaded to 4MFW at 2 8 days

-, ^(G. Winter ,1972)

.

^>