Developments in the design of masonry buildings in Southern California

Citation preview

DEVELOIMENTS IN THE DESIGN OF MASONRY BUILDINGS IN SOUTHERN CALIFORNIA

A T h e sis P r e s e n te d to th e F a c u lt y o f th e S ch o o l o f E n g in e e rin g The U n i v e r s i t y o f S o u t h e r n C a l i f o r n i a

In P a r t ia l F u lfillm e n t o f t h e R e q u i r e m e n t s f o r t h e D e g ree M a ste r o f S c ie n c e i n C i v i l E n g in e e rin g

by R o b e r t Cameron A dolphe J u n e 1950

UMI Number: EP41887

All rights reserved INFORMATION TO ALL USERS The quality of this reproduction is dependent upon the quality of the copy submitted. In the unlikely event that the author did not send a complete manuscript and there are missing pages, these will be noted. Also, if material had to be removed, a note will indicate the deletion.

Dissertation Publishing

UMI EP41887 Published by ProQuest LLC (2014). Copyright in the Dissertation held by the Author. Microform Edition © ProQuest LLC. All rights reserved. This work is protected against unauthorized copying under Title 17, United States Code

ProQuest LLC. 789 East Eisenhower Parkway P.O. Box 1346 Ann Arbor, Ml 48106- 1346

f

^

/

'O

u

i

f

T h is thesis, w ritten hy

K o b e r t Uameron A do lp he under the gu idance of hSLS... F acu lty C o m m ittee, and a p p r o v e d by a ll its m em bers, has been presen ted to and accepted by the C ou n cil on G radu ate S tu d y and R esearch in p a r tia l fu lfill­ m ent of the requirem ents f o r the degree of

......................... y i v i l . _ ^ £ i n e e r j l ^ .........................

Date

J u n e ..1950.^.........

Faculty Committee

Chairman

ii TABLE OF CONTENTS CHAPTER I.

PAGE

THE PROBLEM AND IMPORTANCE OF THE STUDY . . . The p r o b l e m

1

• • • • • •

1

S ta te m e n t o f th e p ro b lem

• • • • • • • •

1

I m p o r ta n c e o f t h e s t u d y

. . . . . . . .

1

R eview o f t h e l i t e r a t u r e

. . . . . . . .

2

S o u r c e s o f d a t a an d t h e t r e a t m e n t o f t h e fin d in g s

• • • • • • • • • • • • • • • •

S ources o f in fo rm a tio n

4

• • • • • • • • •

4

O r g a n iz a tio n o f th e re m a in d e r o f th e th e s is II.

• • • • • • • • • • • • • • • •

DEVELOPMENT OF MASONRY CONSTRUCTION IN SOUTHERN CALIFORNIA...........................................

III.

4

. .

6

H is to ry o f b u ild in g i n S o u th e rn C a l i f o r n i a .

6

H is to ry o f e arth q u ak e s in C a lif o r n ia

8

. . .

D e v e lo p m e n t

o f m e th o d s o f s e i s m i c d e s i g n

•

10

A d o p tio n o f

t h e u s e o f r e i n f o r c e d m a s o n ry •

12

TYPES OF MASONRY CONSTRUCTION AND MATERIALS U S E D ......................................

13

T y p es o f m a s o n r y c o n s t r u c t i o n i n common u s e th ro u g h o u t S o u th e rn C a li f o r n ia P l a i n s o l i d m asonry

• • • • •

13

• • • • • • • • • •

13

G ro u te d b r i c k m a s o n ry • • • • • • • • • •

15

iii CHAPTER

PAGE R e i n f o r c e d g r o u t e d m a s o n ry . . . ................................... 17 H o llo w u n i t m a s o n r y ................................................................18 R e in fo rc e d c o n c r e te b lo c k m asonry

.........................

18

U n b u rn e d b r i c k m a s o n ry ( a d o b e ) ........................• • •

19

M a t e r i a l s .............................................................................................20 M a t e r i a l s u se d i n m a s o n ry c o n s t r u c t i o n • • • .

20

B r i c k ..................................................................................................20 C o n c r e t e b l o c k .........................................................................

21

M o r t a r ..................................................................................................21 Gro u

t ..................................................................................................22

R e i n f o r c i n g s t e e l ...................................... IV .

DESIGN LOADS.................................................... Dead l o a d s ......................................

23 24 24

D e f i n i t i o n ........................................................................................ 24 L iv e l o a d s • • •

...................................................................

D e fin itio n

.............................

24 24

D e s i g n l i v e l o a d s ..............................................................

24

P a r t i t i o n l o a d s ...................................................................

25

R e d u c tio n o f l i v e lo a d s

25

• • • • • • • • • • •

A rra n g e m e n t o f l i v e l o a d s ........................................... Wind l o a d .......................

25 27

A s s u m p t i o n s ................................................................................... 27 D e s ig n w in d l o a d s ......................................

27

In c re a s e in d e sig n s t r e s s e s

28

.......................................

iv CHAPTER

PAGE E a r t h q u a k e l o a d s .................................................................... F orce

............................................................................

I n c r e a s e i n d e s i g n s t r e s s e s ................... ..... . V.

28 28 •

29

APPLICATION OF LATERAL FORCES IN THE DESIGN OF MASONRY BUILDINGS

..............................

31

A p p l i c a t i o n o f l a t e r a l l o a d s .......................................

31

Wind l o a d

• • • .

.

......................................................

S e i s m ic l o a d .......................................................... .... D is tr ib u tio n o f l a t e r a l lo a d s w a l l s an d p a r t i t i o n s

to sh e a r• •

•

31 •

31

• •

............................................

31

B u i l d i n g s w i t h wood r o o f d ia p h r a g m s o r h o r i z o n t a l t r u s s e s .....................................................

31

C o n c r e t e r o o f d i a p h r a g m s ............................................

35

P ro p o rtio n in g lo ad s in r e s i s t i n g

V I.

e le m e n ts

. ♦

36

S h e a r w a l l s ........................................................................

36

F r o n t f r a m e s .........................................................................

39

EMPLOYMENT OF METHODS OF ANALYSIS AND DESIGN PROCEDURE.................................

41

F o o tin g s • • • • • • • • •

42

............................................

W a ll f o o t i n g s ...................................................................

42

E c c e n t r i c w a l l f o o t i n g s ..........................................

44

W a l l s , c o lu m n s , a n d beams •

.......................................

45

W a l l s .......................................................................................

45

Columns

46

CHAPTER

PAGE B e a m s ................................................................................................. 47

Roof D i a p h r a g m s .............................................................................. 49 Wooden r o o f d i a p h r a g m s ...................................................... 50 D e s ig n l o a d s

........................................................................

51

A n ch o rag e o f wooden d i a p h r a g m s ................................... 51

¥11.

L i g h t g a g e s t e e l d e c k i n g u se d a s d ia p h r a g m s •

52

R e i n f o r c e d c o n c r e t e d ia p h r a g m s

53

SUMMARY AND CONCLUSIONS Summary

.............................

................................................. 55

............................................................................................ 55

C o n c l u s i o n s ......................................................... BIBLIOGRAPHY................................................................... APPENDIX.

56 57

S t r u c t u r a l P l a n s , S p e c i f i c a t i o n s , and C o m p u ta tio n s f o r a R e i n f o r c e d G r o u te d B r i c k W areho use B u i l d i n g

.............................................58

LIST OF TABLES TABLE I* II.

PAGE D e s i g n L iv e L o a d s ............................

• « «

26

D i s t r i b a t i o n o f Wind L o a d s t o S h e a r W a l l s ................................................................33

III.

D i s t r i b a t i o n o f S e i s m ic L oads t o S h e a r W a l l s .....................................

« « • •

34

LIST OF FIGURES FIGURE

PAGE

1.

T y p i c a l M a so n ry C o n s t r u c t i o n ............................................................ 16

2*

A p p l i c a t i o n o f L a t e r a l L o a d s ............................................................30

3.

D i s t r i b u t i o n o f L a t e r a l Loads t o S h e a r W a l l s ........................................................................................32

4*

T y p e s o f S h e a r W a l l s .........................................................................

38

5.

M ethod o f T y in g a n E c c e n t r i c F o o t i n g ........................................... 44

m

CHAPT

I

THE PROBLEM MW IMPORTANCE OF THE STUDY As a r e s u l t o f t h e n e c e s s i t y f o r c o n s t r u c t i n g b u i l d ­ i n g s w h ic h x ^ i l l b e s a f e i n c a s e o f e a r t h q u a k e d i s t u r b a n c e s common i n S o u t h e r n C a l i f o r n i a , s p e c i a l s t r u c t u r a l d e s i g n p r o c e d u r e s h a v e b e e n d e v e l o p e d w h ic h a r e , i n g e n e r a l p e c u l i a r t o t h i s area* X*

THE PROBLEM

S ta te m e n t o f th e p ro b lem *

I t i s th e purpose o f t h i s

stu d y to i n v e s ti g a t e a l l a v a i la b l e in fo rm a tio n p e r ta in in g to t h e d e s i g n o f m a s o n ry b u i l d i n g s a s p r a c t i c e d i n S o u t h e r n C a l i f o r n i a , and t o i n c o r p o r a t e t h e s e d e s i g n p r i n c i p l e s , m e th o d s and p r o c e d u r e s i n one w o rk , o u t l i n i n g a n d i l l u s t r a ­ t i n g th e p e r tin e n t s te p s i n c a rry in g o u t th e d e sig n o f t y p i c a l m a s o n ry s t r u c t u r e s . Im p o rta n ce o f th e s t u d y .

M asonry i s one o f t h e m o st

w id e ly used b u i ld i n g m a t e r i a l s i n S o u th e rn C a l i f o r n i a . S e c o n d o n l y i n i m p o r t a n c e t o wood, i t i s u s e d p r i n c i p a l l y f o r s c h o o l s , t h e a t r e s , a n d a l l t y p e s o f c o m m e rc ia l and i n ­ d u s tr ia l b u ild in g s. A p p lic a tio n o f th e s o - c a l l e d se ism ic f a c t o r i s r e ­ s t r i c t e d t o r e l a t i v e l y few a r e a s i n t h e U n i t e d S t a t e s , m o st .

o f which, a r e n e a r b y .

Hence k n o w le d g e o f t h e p r i n c i p l e s ,

t e c h n i q u e s , an d p r o c e d u r e s e m plo yed l o c a l l y i n t h e d e s i g n o f m a s o n ry b u i l d i n g s i s l i m i t e d t o a r e l a t i v e l y s m a l l num ber o f s t r u c t u r a l e n g in e e rs . The volum e o f l i t e r a t u r e d e v o t e d t o m a s o n ry b u i l d i n g d e s i g n i s s m a l l a s c o m p a re d t o t h e w r i t i n g s on c o m p a r a b le ty p e s o f c o n s tru c tio n .

T h i s i s p r o b a b l y p a r t i a l l y due t o

t h e f a c t t h a t m aso n ry d e s i g n h a s b e e n l a r g e l y n e g l e c t e d i n e n g i n e e r i n g s c h o o l a c a d e m ic s c h e d u l e s . new e n g i n e e r i n g g r a d u a t e h a s l i t t l e

As a r e s u l t , t h e

o r no k n o w le d g e o f t h i s

v e ry im p o rtan t phase o f s t r u c t u r a l e n g in e e rin g .

F u rth e rm o re

due t o t h e l a c k o f l i t e r a t u r e , t h e r e h a s b e e n no o p p o r t u n i t y i f o r t h e a v e r a g e e n g i n e e r t o g a i n t h i s k n o w le d g e . T h is s t u d y i s an a t t e m p t t o p a r t i a l l y f i l l t h e v o i d t h a t e x i s t s in th e p ro fe s s io n a l l i t e r a t u r e . R eview o f t h e l i t e r a t u r e . i s l o c a l , v ery l i t t l e

In a s m u c h a s t h e p r o b le m

i n f o r m a t i o n r e g a r d i n g d e s i g n o f m ason­

r y f o r l a t e r a l f o r c e s h a s f o u n d i t s way i n t o t h e t e c h n i c a l lite ra tu re .

T hose few w o rk s t h a t h a v e b e e n p u b l i s h e d a r e

r e s t r i c t e d t o s p e c i a l i z e d s u b j e c t s , a n d a s f a r a s i s known, no a t t e m p t h a s b e e n made t o c o r r e l a t e t h e s e w o rk s a n d t o i n c l u d e i n one volum e t h e b e s t a v a i l a b l e i n f o r m a t i o n r e g a r d ­ i n g l o c a l m aso n ry d e s i g n p r a c t i c e s .

The S t r u c t u r a l C la y

P r o d u c t s I n s t i t u t e h a s p u b l i s h e d t h e o n l y known co m p re-

h e n s i v e w ork on m a s o n ry d e sig n .^ *

T h is t r e a t i s e i s l i m i t e d

t o t h e t r e a t m e n t o f b r i c k and d o e s n o t c o v e r l o c a l d e s i g n p r a c t i c e s , b e i n g i n t e n d e d r a t h e r a s a g e n e r a l w ork a p p l i ­ c a b l e t o a l l p a r t s o f t h e c o u n tr y # W a ile s -B a g e m a n , I n c . 2 and t h e D a v id s o n B r i c k C o . , 3 i n L os A n g e le s h a v e p u b l i s h e d m a n u a ls f o r d e s i g n o f c o n c r e t e b lo c k and b r i c k .

B o th a r e r e c e n t p u b l i c a t i o n s , t h e f o r m e r

h a v i n g b e e n p u b l i s h e d some tim e a f t e r t h i s i n v e s t i g a t i o n was u n d e rta k en .

T h ese p a m p h l e t s , th o u g h c o n t a i n i n g a w e a l t h o f

s p e c i a l i z e d i n f o r m a t i o n f o r t h e d e s i g n e r and b u i l d e r i n S o u t h e r n C a l i f o r n i a , w e re p u b l i s h e d t o p r o m o te t h e s a l e o f p a r t i c u l a r p r o d u c t s , an d so a r e l i m i t e d i n s c o p e . F u rth e rm o re , n e i t h e r a re s u i t a b l e as i n s t r u c t i o n a l te x ts.

N e v e r th e le s s , b o th have p ro v ed in v a lu a b le to

e n g in e e r s and a r c h i t e c t s i n th e S o u th e rn C a l i f o r n i a a r e a . I n s o f a r a s i s know n, t h e y a r e t h e o n l y p u b l i c a t i o n s d e a l ­ i n g s p e c i f i c a l l y a n d e x c l u s i v e l y w i t h l o c a l m a s o n ry b u i l d ­ in g d e sig n p ro c e d u re .

H. C. Plummer and L . J . R e a r d o n , P r i n c i p l e s o f B r i c k E n g i n e e r i n g — Handbook o f D e s i g n , ( W a s h in g to n , D .C .: S t r u c t u r a l C la y P r o d u c t s I n s t i t u t e , 1939) 400 p p . 2 W a ll B lo c L i g h t w e i g h t M a so n ry —M anu al f o r D e s i g n * (Los A n g e l e s ; C a l i f o r n i a ; W a ile s -B a g e m a n , I n c . , 1948) 9 4 p p . S t e e l t y d e R e i n f o r c e d G r o u te d B r i c k M a so n ry D e s i g n . (L os A n g e l e s : C a l i f o r n i a ; D a v id s o n B r i c k Co. 1 94 6) 80 p p .

4 II.

soimcis

OF DATA AND THE TREATMENT OF THE FINDINGS

S ources o f In fo rm a tio n .

The i n v e s t i g a t i o n i n v o l v e d

i n a s s e m b lin g t h i s s tu d y c o n s i s t e d o f a c o n s c ie n tio u s re v ie w o f th e te c h n ic a l l i t e r a t u r e ,

te x tb o o k s , m an u fa ctu rers* l i t e r ­

a t u r e an d d e s i g n d a t a and l o c a l b u i l d i n g c o d e s .

In a d d itio n

t h e w r i t e r drew h e a v i l y upon h i s p e r s o n a l e x p e r i e n c e , h a v i n g b e e n e m p lo y ed f o r two a n d o n e - h a l f y e a r s i n t h e D e p a rtm e n t o f B u i l d i n g and S a f e t y , C i t y o f Los A n g e l e s , r e v i e w i n g and c h e c k in g p la n s and d e s ig n c o m p u ta tio n s f o r a l l ty p e s o f c o m m e rc ia l and i n d u s t r i a l b u i l d i n g s , a l a r g e p e r c e n t a g e o f w h ic h w ere o f m a s o n ry c o n s t r u c t i o n . O rg a n iz a tio n o f th e re m a in d e r o f th e t h e s i s .

The

a t t e m p t h a s b e e n t o com bine t h e i n f o r m a t i o n g l e a n e d f r o m t h e v a r i o u s , s o u r c e s , t o d e t e r m i n e t h e a p p r o p r i a t e m e th o d s o f a n a l y s i s f o r e a c h o f t h e com ponent e l e m e n t s o f b u i l d i n g s , and t o p r e s e n t th em i n a fo rm p a t t e r n e d a f t e r a t y p i c a l t e x t b o o k o f a n a l y s i s and d e s i g n . The s t u d y h a s b e e n d i v i d e d i n t o c h a p t e r s d e v o t e d t o (1) a h i s t o r y o f t h e l o c a l d e v e lo p m e n t o f m a so n ry c o n s t r u c ­ tio n ,

(2 ) a d e s c r i p t i o n o f t h e m a t e r i a l s and t y p e s o f

m a s o n ry commonly u s e d ,

(3 ) e n u m e r a t i o n a n d d i s c u s s i o n o f

t h e l o a d s t o be c o n s i d e r e d i n d e s i g n i n g m a s o n r y , c a t i o n o f th e s e l o a d s , and f i n a l l y

(4 ) a p p l i ­

(5) t h e a c t u a l p r o c e d u r e

e m p lo y ed i n d e s i g n i n g t h e com ponent s t r u c t u r a l e l e m e n t s o f

5

b u ild in g s .'

F u r t h e r i l l u s t r a t i n g t h e s u b j e c t , and i n o r d e r

t h 8 t t h e p r a c t i c a l a p p l i c a t i o n o f t h e p r i n c i p l e s and p r o ­ c e d u r e s d e s c r i b e d h e r e i n may be d e m o n s t r a t e d , a c o m p le te s e t o f s t r u c t u r a l p l a n s , d e s i g n c a l c u l a t i o n s , and s t r u c t u r ­ a l s p e c i f i c a t i o n s f o r a 9 0 1 by 148* r e i n f o r c e d b r i c k w a r e ­ house o r i n d u s t r i a l b u ild in g have been in c lu d e d as th e A p p e n d ix .

The b u i l d i n g , w h ic h was c o n c e i v e d e s p e c i a l l y f o r

u s e i n c o n n e c t i o n w i t h t h i s w ork was d e l i b e r a t e l y d e s i g n e d t o i n c l u d e a v a r i e t y o f c o n d i t i o n s , a l l o f w h ic h a r e common lo c a lly .

CHAPTER I I

DEVELOPMENT OF MASONRY CONSTRUCTION IN SOUTHERN CALIFORNIA H is to r y o f b u ild in g i n S o u th e rn C a l i f o r n i a ,

The

E i g h t e e n t h C e n t u r y m ark ed t h e c u l m i n a t i o n o f t h e g r e a t e s t s e r i e s o f c o n q u e s t s s i n c e t h e b e g i n n i n g o f man; t h a t o f S o u t h a n d C e n t r a l A m erica and o f t h e S o u t h w e s t p a r t o f N o r th A m erica by t h e S p a n i a r d s ,

M exico h a d b e e n o c c u p i e d f o r two

h u n d r e d and f i f t y y e a r s when r o y a l o r d e r s w ere r e c e i v e d fro m t h e h o m e la n d t o o c c u p y and c o l o n i z e A l t a C a l i f o r n i a , As i n p r e v i o u s c o n q u e s t s , m i l i t a r y s u b j u g a t i o n was f o l l o w e d by s e c u l a r e d u c a t i o n .

So, hand i n hand w ith th e

c o n a u i s t i d o r e s came t h e p r i e s t s , who w e re a t o n c e c o m f o r t e r s o f wayward h e a t h e n s o u l s a s w e l l a s e d u c a t o r s .

W ith them

t h e y b r o u g h t s k i l l e d a r t i s a n s and c r a f t s m e n ; and o n e o f t h e f i r s t s t e p s w as t o t e a c h t h e n a t i v e I n d i a n s t h e b u i l d i n g tra d e s. A b u i l d i n g m a t e r i a l was n e e d e d t h a t was s t r o n g and r i g i d ; on e t h a t was immune t o r o t , v e rm in a t t a c k , o x i d a t i o n , a n d f i r e h a z a r d s ; one t h a t p r o v i d e d i n s u l a t i o n a g a i n s t t h e sun and, m ost im p o r ta n t o f a l l ,

one t h a t was a v a i l a b l e i n

q u a n ti t y in th e g r e a t t r e e l e s s slo p e s o f S o u th e rn C a l i f o r n i a . And s o , i n t h e y e a r s b e tw e e n 1769 an d 1 8 2 5 , when F r a J u n i p e r o S e r r a e s t a b l i s h e d . t w e n t y - o n e m i s s i o n s b e tw e e n

S an D iego a n d Sonoma, t h e s e b u i l d i n g s w e re b u i l t p r i n c i p a l l y o f m a s o n ry c o n s t r u c t i o n .

They w ere p a t t e r n e d a f t e r t h e

m a s o n ry a r c h i t e c t u r e w h ic h p r e d o m i n a t e d i n S p a i n and Morocco ( w i t h some m o d i f i c a t i o n an d a g r e a t d e a l o f s i m p l i f i c a t i o n ) w h ere good l i m e , c em en t a n d s t o n e a b o u n d e d .

B ut s u c h

m a t e r i a l s w e re n o t a v a i l a b l e i n q u a n t i t y i n S o u t h e r n C a l i f ­ o r n i a , a n d s o , i n f e r i o r u n b u rn e d b r i c k s an d t r i a n g u l a r , s o f t - s a n d s t o n e s p a l l s , o r rounded s tre a m -b e d b o u ld e r s , l a i d i n l i m e l e s s mud w e re u se d i n t h e o r i g i n a l m i s s i o n s and p u e b lo s.

T h i s ado be b r i c k c o n s t r u c t i o n p r e d o m i n a t e d i n

S o u th e rn C a l i f o r n i a even a f t e r th e In g lo -S a x o n im m ig ra tio n began a f t e r th e f i r s t q u a r t e r o f th e N in e te e n th C e n tu ry . D e s p i t e t h e f a c t t h a t a d o b e m a s o n ry s a t i s f i e d so many o f t h e r e q u i r e m e n t s o f t h e i d e a l b u i l d i n g m a t e r i a l f o r t h e r e g i o n , i t p o s s e s s e d s e v e r a l i n h e r e n t d e f e c t s w h ic h made i t p a r t i c u l a r l y u n s u ita b le f o r th e b u ild in g needs o f t h i s v ic in ity .

T h ese b u i l d i n g s w ere b u i l t by l i m i t e d l y s k i l l e d

I n d i a n a r t i s a n s a n d s o w e re i n f e r i o r i n c o n s t r u c t i o n , w i t h ­ o u t p r o p e r r e i n f o r c e m e n t , i f a n y , and t h e u n b u rn e d b r i c k s p o s s e s s e d e x t r e m e l y low c r u s h i n g and t e n s i l e s t r e n g t h s . F u r t h e r m o r e , t h e ado be b r i c k s and m o r t a r f u r n i s h e d o n l y l i m i t e d r e s i s t a n c e t o p e n e t r a t i o n o f w a t e r an d a b r a s i o n due t o w ind a n d r a i n . As s e t t l e m e n t a n d i n d u s t r i a l i z a t i o n o f t h e a r e a p r o ­ g r e s s e d , k i l n s w e re b u i l t , a n d b u r n e d c l a y o r s h a l e b r i c k

8 r e p l a c e d t h e o l d u n b u r n e d ado be b r i c k o f t h e m i s s i o n d a y s . T h i s b u rn e d c l a y o r s h a l e b r i c k w i t h much g r e a t e r c o m p re s­ s i v e an d s h e a r i n g s t r e n g t h , im p o sed f e w e r l i m i t a t i o n s . E ven th o u g h lu m b e r and f e r r o u s m e t a l s became a v a i l a b l e t h r o u g h e s t a b l i s h m e n t o f e f f i c i e n t t r a n s p o r t a t i o n and s h i p p i n g f a c i l i t i e s , p l a i n b r i c k m a s o n ry c o n s t r u c t i o n con­ t i n u e d t o p r e d o m i n a t e f o r c o m m e rc ia l and i n d u s t r i a l b u i l d ­ i n g s i n S o u t h e r n C a l i f o r n i a u n t i l J u n e 2 9 , 1 9 2 5 , when a s e v e r e and p r o p e r t y d am aging e a r t h q u a k e o c c u r r e d i n t h e C i t y o f S a n ta B a rb a ra . H isto ry o f e a rth q u a k e s in C a lif o r n ia .

R ecords o f th e

s h a k e s and t r e m o r s w h ic h h a v e t a k e n p l a e e i n S o u t h e r n C a l i f ­ o r n i a h a v e b e e n made u n t i l q u i t e r e c e n t l y w i t h o u t s y s te m o r s c i e n t i f i c s u p e r v i s i o n , and u s u a l l y w i t h e x a g g e r a t e d d e t a i l . I n f a c t , few f a c t s a b o u t t h e q u a k e s o f t h e l a s t c e n t u r y h a v e been p re s e rv e d .

A rev iew o f th e s c i e n t i f i c

j o u r n a l s w h ic h

h a v e p u b l i s h e d t h e r e s u l t s o f r e s e a r c h made t o a s c e r t a i n t h e e a r t h q u a k e h i s t o r y o f C a l i f o r n i a i n d i c a t e s a tre m e n d o u s num­ b e r and w id e d i s t r i b u t i o n o f q u a k e s d u r i n g t h e p a s t two hundred y e a r s .

The m o s t s e v e r e sh o c k s o c c u r r e d i n 1769,

1 8 1 3 , 1 8 5 7 , 1 8 6 8 , 1 8 7 2 , 1 9 0 6 , 1 9 2 5 , 4 a n d 1933.

^ R o b e r t T . H i l l , S o u t h e r n C a l i f o r n i a G eo lo g y and L os A n g e le s E a r t h q u a k e s . (Los A n g e l e s , C a l i f o r n i a : S o u th e rn C a l i f o r n i a Academy o f S c i e n c e s , 1 9 2 8 ) .

9 The f a l l i n g o f t h e t o w e r o f t h e o l d adobe m i s s i o n c h u ro h a t San J u a n C a p i s t r a n o i n 1818 (89 p e r s o n s h a v i n g b e e n k i l l e d t h e r e b y ) a n d o f adobe b u i l d i n g s a t Yuma and T e j o n i n 1 8 5 7 , w e re t h e o u t s t a n d i n g e a r t h q u a k e d i s a s t e r s o f S o u t h e r n C a l i f o r n i a p r i o r t o t h e h i s t o r i c Long B each e a r t h ­ qu ak e w h ic h o c c u r r e d i n 1933*

Y e t n e i t h e r e x e r t e d any

p e rm a n e n t e f f e c t upon t h e m e th o d s o r m a t e r i a l s em ployed i n m a s o n ry c o n s t r u c t i o n i n t h i s a r e a .

R a t h e r i t was t h e S a n t a

B a r b a r a e a r t h q u a k e o f 1 9 8 5 , w h ic h p r e c i p i t a t e d t h e t r e n d t o w a r d s a w a r e n e s s o f s e i s m i c d i s t u r b a n c e s i n t h i s r e g i o n and f i n a l l y a d o p tio n o f a s o - c a l l e d se ism ic f a c t o r in th e d e s ig n o f b u i l d i n g s a f t e r t h e Long B each e a r t h q u a k e .

I t m u s t , how­

e v e r , be p o i n t e d o u t t h a t t h i s l o c a l d i s t u r b a n c e f o l l o w e d t h e fam ous Tokyo o r Kwanto e a r t h q u a k e , w h ic h o c c u r r e d on t h e 1 s t o f S e p t e m b e r , 1 9 8 3 , and w h ic h , t h o u g h n o t t h e g r e a t e s t e a r t h q u a k e on r e c o r d , was t h e f i r s t t o be l i s t e d n a tio n a l r a t h e r th a n a r e g io n a l c a la m ity .

as a

The l o s s o f l i f e

was a b o u t 8 5 0 ,0 0 0 w i t h a c o r r e s p o n d i n g l y l a r g e r num ber o f in ju re d .

More t h a n one m i l l i o n p e r s o n s i n Tokyo a l o n e w ere

re n d e re d h o m e le ss.^

The l o s s o f p r o p e r t y r e p r e s e n t e d a t

l e a s t two a n d o n e - h a l f b i l l i o n d o l l a r s .

T h is was t h e f i r s t

g r e a t e a r t h q u a k e f o r w h ic h s e i s m o l o g i s t s w ere r e a d y w i t h a

5 N. H. P e c k , E a r t h q u a k e s * ( P r i n c e t o n , New J e r s e y : P r i n c e t o n U n i v e r s i t y P r e s s , 1 9 3 6 ) . pp 1 1 5 - 1 1 9 .

10 w id e d i s t r i b u t i o n o f i n s t r u m e n t s , some o f w h ic h w e re c a p a b l e o f r e c o r d in g th e s t r o n g e a r t h m o tio n s.

In s p ite o f th e lo s s

o f many i n s t r u m e n t s an d damage t o o t h e r s w h ic h s p o i l e d t h e i r r e c o r d s , e n o u g h i n f o r m a t i o n was o b t a i n e d t o c o n s t i t u t e an i n v a l u a b l e a d d i t i o n t o k n o w le d g e d i r e c t e d t o w a rd t h e p r e ­ v e n t i o n o r r e d u c t i o n o f e a r t h q u a k e dam age. D e v elo p m en t o f m e th o d s o f s e i s m i c d e s i g n .

The s e n ­

s a t i o n a l an d t r a g i c Tokyo e a r t h q u a k e s e r v e d t o make t h e w o r l d e a r t h q u a k e c o n s c i o u s , and s p u r r e d e n g i n e e r s , e s p e c i a l l y in a re a s o f h ig h s e is m ic ity ,

t o d e v e l o p and i n ­

c o r p o r a t e i n t o l o c a l b u i l d i n g c o d e s d e s i g n p r o c e d u r e s w h ic h w o u ld g u a r a n t e e b u i l d i n g s s a f e fro m e a r t h q u a k e dam age. So when t h e S a n t a B a r b a r a e a r t h q u a k e o c c u r r e d , l o c a l e n g i n e e r s b e g a n t o s t u d y t h e s t r e s s e s c a u s e d by e a r t h q u a k e s and m e th o d s o f d e s i g n w h ic h h a d b e e n a d o p t e d i n o t h e r c o u n ­ trie s .

I n v e s t ig a ti o n s had in d ic a te d t h a t c o m p a ra tiv e ly

little

was known a b o u t t h e s t r e s s e s , and t h a t t h e w h o le

p r o b le m was v e r y c o m p le x .

F u rth e rm o re , th e f a c t t h a t th e

l o a d s w e re dynam ic r a t h e r t h a n s t a t i c p o s e d a s p e c i a l p r o b ­ lem in a s m u c h a s b u i l d i n g d e s i g n p r o c e d u r e s and b u i l d i n g c o d e s w e re b a s e d on t h e p r e m i s e t h a t a l l l o a d s im p o sed on a s t r u c t u r e a re c o n s ta n t r a t h e r th an i n t e r m i t t e n t .

In o th e r

w o r d s , t h e la w s o f s t a t i c s o n l y w ere u s e d i n d e s i g n i n g b u i l d ­ i n g s , and t h e q u e s t i o n now a r o s e a s t o w h e t h e r e n t i r e l y new

11 t h e o r i e s s h o u l d be e v o l v e d and d e s i g n f o r dynam ic l o a d i n g be in c o rp o ra te d in to lo c a l b u ild in g codes. A g re em en t o f i d e a s and i n c o r p o r a t i o n i n t o l o c a l b u i l d ­ i n g c o d e s o f a s e t p r o c e d u r e was n o t a c c o m p lis h e d i n t h e few y e a rs fo llo w in g th e S a n ta B arb ara e a rth q u a k e , b u t s u f f i c i e n t t h o u g h t was g i v e n t h e m a t t e r and i n v e s t i g a t i o n and s t u d y c a r r i e d t o s u c h an e x t e n t t h a t when t h e Long B each e a r t h ­ quak e o f M arch 1 0 t h , 1 9 3 3 , o c c u r r e d , t h e s o - c a l l e d e a r t h ­ quake law was e n a c t e d by t h e C a l i f o r n i a S t a t e L e g i s l a t u r e i n May o f t h e same y e a r .

I n O c t o b e r o f 1 9 3 3 , t h e C i t y o f Los

A n g e le s i n c o r p o r a t e d r e q u i r e m e n t s f o r s e i s m i c d e s i g n i n t o th e b u ild in g code. T h e s e p r o v i s i o n s w ere p a t t e r n e d a f t e r t h e p l a n a d o p t ­ e d b y t h e J a p a n e s e and w h ic h h a s b e e n f o l l o w e d e l s e w h e r e . T h is p l a n c o n s i s t e d o f u sin g a s o - c a l l e d s e is m ic f a c t o r i n th e d e sig n o f b u ild in g s .

In o t h e r w ords, th e b u ild in g i s

made s t r o n g enough t o r e s i s t a h o r i z o n t a l f o r c e e q u a l t o a c e r t a i n p r o p o r tio n o f th e w e ig h t o f th e b u ild in g .

S in c e

w e i g h t i s e x p r e s s e d i n t e r m s o f t h e a c c e l e r a t i o n due t o g r a v i t y , t h e h o r i z o n t a l f o r c e i s e x p r e s s e d i n t h e same w ay, and i t i s p o s s i b l e t o com pare t h i s f o r c e w i t h m e a s u r e d o r c o m p u ted a c c e l e r a t i o n s o f t h e e a r t h q u a k e .

A se ism ic f a c t o r

o f 1 / 1 0 h a d b e e n u s e d i n J a p a n w i t h good r e s u l t s , a s shown i n t h e 1923 e a r t h q u a k e . L o c a l cod e r e q u i r e m e n t s f o r s e i s m i c d e s i g n w i l l be

12 d i s c u s s e d i n d e t a i l i n C h a p t e r 17 . A d o p tio n o f t h e use o f r e i n f o r c e d m a s o n r y .

R e q u ire ­

m e n ts f o r s e i s m i c d e s i g n r a n g t h e d e a t h k n e l l f o r p l a i n b r i c k m a s o n ry and u s h e r e d i n t h e e x t e n s i v e use o f a r e v o l u t i o n a r y m a s o n ry d e s i g n p r o c e d u r e i n S o u t h e r n u a l i f o r n i a , t h a t o f r e i n f o r c i n g m a s o n ry w i t h s t e e l b a r s a n d e m p lo y in g d e s i g n m e th o d s w h ic h c o n s i d e r t h e b r i c k t o be a hom ogeneous m a t e r i a l a c t i n g much t h e same a s r e i n f o r c e d c o n c re te . The r e q u i r e d u se o f r e i n f o r c e d m a s o n ry h a s r e s u l t e d i n t h e d e v e lo p m e n t o f many new c o n s t r u c t i o n p r a c t i c e s , t h e m o s t i m p o r t a n t o f w h ic h i s t h e g r o u t i n g m etho d o f c o n stru c tio n .

T h i s m eth o d c o n s i s t s o f f i l l i n g a l l i n t e r i o r

j o i n t s , l i n c l u d i n g t h e i n n e r p o r t i o n s o f t h e h e a d and bed w y th e s, w ith a f r e e l y flo w in g g r o u t. a re used.

Ho m a s o n ry h e a d e r s

G r o u t i n g i n t h i s m an n er b i n d s t h e e n t i r e g ro u p

o f b r i c k s i n t o a s o l i d m ass and e l i m i n a t e s t h e d a n g e r o f p a r t i a l l y f i l l e d m o rta r j o i n t s .

I n S o u th e rn C a l i f o r n i a ,

g r o u t i n g i n t e r i o r j o i n t s i n r e i n f o r c e d b r i c k m a s o n ry h a s c o m p l e t e l y r e p l a c e d t h e f o r m e r m ethod o f f i l l i n g w i t h m o rta rs o f b ric k la y in g c o n s is te n c y .

CHAPTER III TYPES OF MASONRY CONSTRUCTION AND MATERIALS USED As s t a t e d i n t h e p r e c e d i n g c h a p t e r , p l a i n m a s o n ry h a s , t o a g r e a t e x t e n t , b e e n s u p p l a n t e d by r e i n f o r c e d m ason­ r y , e i t h e r b r ic k o r c o n c re te b lo c k , s in c e req u ire m e n ts f o r s e i s m i c d e s i g n w ere i n c o r p o r a t e d i n t o l o c a l b u i l d i n g c o d e s in 1933.

H ow ever, a g r e a t num ber o f b u i l d i n g s o f p l a i n ma­

s o n r y e x i s t i n t h i s a r e a , many o f w h ic h a r e , upon o c c a s i o n , b e in g a l t e r e d o r added t o .

F u rth erm o re, n o n -b e a rin g w a lls

w i t h in c e r t a i n h e ig h t l i m i t s a re s t i l l b e in g c o n s tr u c te d o f p l a i n m asonry.

T h e r e f o r e , a l l m ajo r c l a s s i f i c a t i o n s o f

m a s o n ry a r e d e s c r i b e d h e r e , a s w e l l a s t h e m a t e r i a l s u s e d . I.

TYPES OF MASONRY CONSTRUCTION

IN COMMON USE THROUGHOUT SOUTHERN CALIFORNIA P l a i n s o l i d m asonry.

P l a i n s o l i d m a s o n ry may be

b r ic k , c o n c re te b r ic k , n a tu r a l o r c a s t s to n e .

In p la in

s o l i d b r i c k m a s o n r y , s t r e t c h e r c o u r s e s a r e bonded by s t a g ­ g e rin g v e r t i c a l j o i n t s .

I n p l a i n s o l i d m asonry o f s to n e ,

t h e bond s t o n e s a r e u n i f o r m l y d i s t r i b u t e d t h r o u g h o u t t h e w a l l and c o m p r i s e 20 t o 25$ o f t h e w a l l s u r f a c e .

M a so n ry u n i t s

a r e l a i d and s e t i n m o r t a r p l a c e d w i t h a t r o w e l and s h o u l d be l a i d w i t h f u l l s h o v e d m o r t a r j o i n t s and a l l h e a d , bed and

14 w a l l j o i n t s s o l i d l y f i l l e d w i t h m o r ta r *

A f t e r b e in g l a i d ,

t h e y s h o u l d be k e p t m o i s t f o r s e v e n days* S u c h m a s o n ry i s r e l i a b l e f o r d e s i g n e d c o m p r e s s i v e stre n g th s.

I t may o r may n o t be r e s i s t a n t t o w a t e r p e n e ­

t r a t i o n , d e p e n d i n g o n ho?,? s o l i d l y t h e v e r t i c a l m o r t a r j o i n t s a r e , e s p e c i a l l y betv^een h e a d e r b r i c k s * C o m p r e s s iv e s t r e n g t h o f common b r i c k i n t h i s a r e a r a n g e s fro m a b o u t 1500 p . s * i *

t o a b o u t 8000 p . s . i *

a v e r a g e v a l u e s o f 2000 t o 4000 p . s . i .

w ith

C o m p re s s iv e s t r e n g t h

o f f a c e b r i c k i n t h i s a r e a r a n g e s fro m a b o u t 4000 p . s . i . a b o u t 1 2 ,0 0 0 p . s . i .

to

L o c a l t e s t s on t y p e A m o r t a r and g r o u t

show c o m p r e s s i v e s t r e n g t h s t o a v e r a g e fro m a b o u t 5500 p . s . i . t o a b o u t 5000 p . s . i . L o c a l c o r e t e s t s on common b r i c k m a s o n r y w i t h t y p e A m o r t a r and g r o u t show c o m p r e s s i v e s t r e n g t h t o a v e r a g e fro m a b o u t 1200 p . s . i .

t o a b o u t 3500 p . s . i . , w i t h jo b a v e r ­

a g e s a b o u t 2000 p . s . i .

T e s t s on m a s o n ry made o f s o f t mud

common b r i c k ? ? ith t y p e A m o r t a r and g r o u t show t e n s i l e s t r e n g t h o f m a s o n r y t o be fro m 175 p . s . i . p .s .i.

t o a b o u t 200

The s h e a r i n g s t r e n g t h o f m a s o n ry i s g r e a t e r t h a n

175 p . s . i .

T h i s i s p r o v e n by t h e f a c t t h a t m a s o n ry t e s t e d

u n d e r l o a d s i n d u c i n g f l e x u r e a lw a y s f a i l b y t e n s i o n . W ork in g s t r e s s e s a l l o w e d b y l o c a l b u i l d i n g d e p a r t ­ m e n ts f a l l f a r b e lo w a c t u a l s t r e n g t h s o f m a s o n r y , due l a r g e l y t o i n c o n s i s t e n c y o f w o rk m an sh ip i n t h e f i e l d , a s

15 w e ll a s , to th e d e s ir a b le f a c t o r o f sa fety *

In g e n e ra l,

w here c o n t i n u o u s i n s p e c t i o n by a r e g i s t e r e d d e p u t y i n s p e c t o r i s e m p lo y e d , t h e a l l o w a b l e s t r e s s e s a r e d o u b le d * The L os A n g e le s C i t y B u i l d i n g Code a l l o w s t h e f o l l o w i n g s t r e s s e s f o r p l a i n m a s o n ry ( b r i c k and c o n c r e t e b ric k ):

70 p * s * i . i n c o m p r e s s i o n ; 6 p . s . i *

i n s h e a r and

t e n s i o n , t e n s i o n b e i n g assum ed t o e x i s t o n l y i n w a l l s s u p p o r t e d l a t e r a l l y t o p an d bottom * G ro u ted b r i c k m aso n ry *

G r o u te d B r i c k m a s o n ry i s

s o l i d m a s o n ry w h e r e i n a l l i n t e r i o r j o i n t s a r e f i l l e d by p o u r i n g P o r t l a n d Cement g r o u t t h e r e i n i n e a c h c o u r s e a s t h e w ork p r o g r e s s e s .

M ost o f t h e f r e e w a t e r i n t h e g r o u t i s

q u i c k l y a b s o r b e d i n t o t h e b r i c k w h e re b y t h e c em en t and s a n d c o n d e n s e s i n t o a v e r y d e n s e m ass h a v i n g v e r y low w a t e r c em en t r a t i o p r i o r t o i n i t i a l w e t .

Due t o t h e a d h e s i o n -

bond s t r e n g t h and t h e d e n s i t y o f t h i s m ass a f t e r h a r d e n i n g , e v e r y b r i c k i s " b o n d e d " a t e v e r y c o u r s e , and i n a d d i t i o n , a w a t e r r e s i s t a n t d ia p h r a g m i s fo rm ed w i t h i n t h e m a s o n r y . T h u s , a s o l i d , w a t e r - t i g h t and s t r u c t u r a l l y d e p e n d a b le m a s o n ry i s o b t a i n e d .

I t i s r e l i a b l e f o r d esig n ed s tr e n g th s

i n c o m p r e s s i o n , s h e a r , and t o some e x t e n t t e n s i o n , and i s h ig h ly r e s i s t a n t to w a te r p e n e tr a tio n . A l l o w a b le w o r k in g s t r e s s e s f o r g r o u t e d b r i c k m a s o n ry a re s l i g h t l y h ig h e r th a n th o se fo r p la in s o lid b ric k m ason ry*

16

He&de ,ih ■.

P l a i n Bric.k Masonry

P l a i n H o l l o w Masonry

V e r t i c a l Wall

R einforced Concrete Block

PICUHS 1 TYPICAL MASC1LPY CONSTRUCTION

Stee

17 R e i n f o r c e d 'g r o u t e d m a s o n r y *

R e i n f o r c e d b r i c k m a s o n ry

i s g r o u t e d b r i c k m aso n ry made up o f two t o f o u r t i e r s o f b r i c k l a i d up i n m o r t a r w i t h r e i n f o r c i n g s t e e l b a r s embedded i n t h e g r o u t e d s p a c e s b e tw e e n them t o r e s i s t s t r e s s e s , g e n ­ e r a l l y o t h e r t h a n c o m p r e s s i o n , and s h e a r .

I t i s c o n sid e re d

t o be hom ogeneous and i s d e s i g n e d i n a c c o r d a n c e w i t h t h e a c ­ c e p te d p r a c t i c e f o r th e d e s ig n o f r e i n f o r c e d c o n c r e te . A llo w a b le s t r e s s e s i n r e i n f o r c e d g r o u t e d m a s o n r y , f o r 2500 p . s . i .

b ric k u n its a re as fo llo w s:

i n a x i a l c o m p r e s s i o n , 250 p . s . i . p .s .i.

135 p . s . i .

i n f l e x u r a l c o m p r e s s i o n , 11

i n s h e a r ( w i t h o u t web r e i n f o r c e m e n t ) , 25 p . s . i .

in

s h e a r w i t h web r e i n f o r c e m e n t t a k i n g 2 / 3 o f t h e s h e a r , 300 p .s .i. b a rs .6

i n b e a r i n g , and 50 p . s . i .

i n bond w i t h d e fo rm e d

The a l l o w a b l e s t r e s s e s f o r 1500 p . s . i .

b rick

u n i t s ©re ©bout t w o - t h i r d s t h e v a l u e s a b o v e , w i t h t h e e x c e p t i o n o f bond s t r e s s , w h ic h i s t h e sam e. The minimum a r e a o f t o t a l w a l l r e i n f o r c e m e n t s h o u l d n o t be l e s s t h a n 0 .0 0 2 t i m e s t h e c r o s s s e c t i o n a l a r e a o f t h e w a l l , n o t m ore t h a n t w o - t h i r d s t o be u s e d i n e i t h e r d i r e c ­ tio n .

V e r t i c a l b a r s s h o u l d be a t l e a s t 3 / 8 ” i n d i a m e t e r

and s p a c e d a t n o t m ore t h a n 3 6 Tf c e n t e r - t o - c e n t e r .

The

r e q u i r e d h o r i z o n t a l s t e e l may be c o n c e n t r a t e d i n bond beams

o rn ia :

6 L os A n g e le s C i t y B u i l d i n g Code (L os A n g e l e s , C a l i f ­ B u i l d i n g Code P u b l i s h i n g Company, 1949)

an d a t t h e t o p s and b o tto m s o f o p e n i n g s w i t h n o t m ore t h a n 50% i n t o p s o f f o o t i n g w a l l s .

I f w a lls a re c o n s tru c te d

o f m ore t h a n two u n i t s i n t h i c k n e s s , t h e r e i n f o r c e m e n t s h o u l d b e e q u a l l y d i v i d e d i n t o two l a y e r s . H o llo w u n i t m a s o n r y .

H o llo w u n i t m a s o n ry may be

h o l lo w c l a y t i l e o r b l o c k o r h o l l o w c o n c r e t e t i l e o r b l o c k l a i d up i n cem ent l im e m o r t a r .

In te rlo c k in g u n its l a i d

w i t h o u t m o r t a r a r e a l s o a p p r o v e d i n some c a s e s .

T h is typ e

o f m a s o n ry i s s u i t a b l e o n l y f o r f i l l e r w a l l s and f o r n o n ­ b e a r i n g p a r t i t i o n s n o t o v e r 10 f e e t h i g h . 45 p . s . i .

i n c o m p r e s s i o n and 6 p . s . i .

S tre sse s of

i n s h e a r and t e n s i o n

a re a llo w e d . R e in fo rc e d c o n c r e te b lo c k m asonry.

R e in fo rc e d

c o n c r e t e b l o c k m a s o n ry i s h o l l o w u n i t m a s o n ry h a v i n g some o f t h e c e l l s f i l l e d w i t h g r o u t i n w h ic h r e i n f o r c i n g s t e e l i s em b ed d ed , a s i l l u s t r a t e d i n F i g u r e 1 , p a g e 1 6 .

P o rtio n s

w h e re c e l l s a r e f i l l e d a r e d e s i g n e d i n a c c o r d a n c e w i t h a c ­ c ep ted d e sig n p ro ced u re f o r r e in f o r c e d c o n c re te . A l l o w a b le s t r e s s e s f o r f i l l e d c e l l c o n s t r u c t i o n i n t h e C i t y o f Los A n g e le s a r e : s i o n , 200 p . s . i .

125 p . s . i . i n a x i a l c o m p re s­

i n f l e x u r a l c o m p r e s s i o n , 10 p . s . i .

s h e a r ( n e t ) , 20 p . s . i .

i n s h e a r w i t h web r e i n f o r c i n g t a k i n g

2 / 3 o f e n t i r e s h e a r , 125 p . s . i . a n d 50 p . s . i .

in

in b e a rin g

i n bond w i t h d e fo rm e d b a r s .

(fille d

c e lls )

As i n t h e c a s e

19 o f b r i c k , t h e s e a l l o w a b l e s t r e s s e s may be d o u b l e d w i t h c o n t i n u o u s i n s p e c t i o n by a r e g i s t e r e d d e p u ty i n s p e c t o r # R e q u ir e m e n t s f o r w a l l r e i n f o r c e m e n t a r e t h e same a s f o r g ro u te d r e in f o r c e d .b ric k . U n b u rn e d b r i c k m a s o n ry ( a d o b e ) .

Though t h e f i r s t ,

and t h e r e a f t e r f o r many y e a r s t h e m o s t commonly u se d m a s o n ry b u i l d i n g m a t e r i a l , ad o b e i s i n r e a l i t y v e r y p o o r l y a d a p t e d t o p r e s e n t - d a y d e s i g n m e th o d s w h ic h r e q u i r e r e s i s t a n c e o f s t r u c t u r e s a g a in s t e a rth q u ak e lo a d s .

In a d d itio n , i t f u r ­

n i s h e s o n l y l i m i t e d r e s i s t a n c e t o p e n e t r a t i o n o f w a t e r and a b r a s i o n due t o t h e e l e m e n t s . F o r m e r l y ad o b e b r i c k s w e re made o f c l a y , s a n d , and s t r a w o r h o r s e m a n u r e , p r o p e r l y p r o p o r t i o n e d , m ix ed w i t h w a t e r by t r e a d i n g w i t h b a r e f e e t .

T o d ay , t h e m ix i n g i s done

i n a cem ent m i x e r o r a s m a l l p u g - m i l l .

S e v e ra l p e tro le u m

p r o d u c ts m a n u fa c tu re rs i n C a l i f o r n i a have ex p erim en ted c o n s i d e r a b l y and now m a r k e t f o r s a l e s o - c a l l e d s t a b i l i z e r s , w h ic h , when m ix e d w i t h mud, endow t h e s u n - d r i e d b r i c k s w i t h an i n c r e a s e d a b i l i t y t o r e s i s t w a t e r p e n e t r a t i o n w h ic h p e r ­ m its i n c r e a s e d co m p ressiv e s t r e n g t h s i n d e s ig n .

T hese

s t a b i l i z i n g a g e n ts a re u s u a lly e m u ls ifie d a s p h a lts .

The

same d e s i g n p r o c e d u r e i s em ployed f o r u n b u rn e d c l a y b r i c k s as f o r o t h e r ty p e s o f r e i n f o r c e d m asonry.

The L os A n g e le s

B u i l d i n g Code a l l o w s d e s i g n s t r e s s e s o f 50 p . s . i .

in

c o m p r e s s i o n and 4 p . s . i .

i n t e n s i o n and s h e a r .

I t lim its

t h e u se o f u n b u rn e d c l a y u n i t s t o one s t o r y b u i l d i n g s and im p o s e s n u m ero u s o t h e r l i m i t a t i o n s .

H a rrin g to n 7 d e s c rib e s

i n d e t a i l t h e p r o c e d u r e s e m p lo y ed i n m ak in g ad o b e b r i c k and c o n s t r u c t i n g a b u i l d i n g o f t h e m a t e r i a l , i n c l u d i n g r e q u i r e m e n t s i n t h e C i t y o f Los .Angeles a s w e l l as i n u n i n c o r p o r a t e d a r e a s i n t h e C o u n ty o f L os .A ngeles. I I . MATERIALS M a t e r i a l s u se d i n m a s o n ry c o n s t r u c t i o n .

The p r i n ­

c i p a l m a t e r i a l c o n s t i t u e n t s o f m a s o n ry i n t h i s a r e a a r e ( a ) b r i c k , c o n c r e t e b l o c k , h o l lo w c l a y b l o c k e r t i l e , gypsum b l o c k o r t i l e , ad o b e b r i c k , and c a s t b u i l d i n g s t o n e , (b) m o r t a r an d g r o u t , a n d (c ) r e i n f o r c i n g s t e e l .

Of t h e

m a s o n ry u n i t s e n u m e r a t e d , b r i c k a n d c o n c r e t e b l o c k a r e u s u a l l y u se d f o r e x t e r i o r and b e a r i n g w a l l s . b lo ck o r t i l e

a n d gypsum b l o c k o r t i l e

H ollow c l a y

a re used u s u a l ly

o n ly f o r n o n -b e a rin g p a r t i t i o n s , n o t o v er te n f e e t h ig h . B ric k .

B r i c k i s made o f b u r n e d c l a y o r s h a l e and

s h o u l d c o n fo rm t o A .S .T .M . " S t a n d a r d S p e c i f i c a t i o n s f o r B u i l d i n g B r i c k , " A .S .T .M . D e s i g n a t i o n 0 6 2 - 4 4 .

The p h y s i c a l

7 M. R. H a r r i n g t o n , How To B u i l d A C a l i f o r n i a Adobe (L os A n g e l e s , C a l i f o r n i a : Ward R i t c h i e P r e s s and t h e S o u t h w e s t Museum, 1948} p p . 1 0 -5 0

21 p r o p e r t i e s o f b r i c k a r e d i s c u s s e d i n g r e a t d e t a i l by Plummer and H e a r d o n .8 S ta n d a rd b u ild in g b r ic k a re 2 1 /4 in c h e s th ic k , 3 3 /4 i n c h e s w id e , and 8 i n c h e s l o n g .

H ow ever, v a r i a t i o n s fro m

t h i s s i z e a r e f r e q u e n t l y f o u n d , d e p e n d i n g upon t h e manu­ f a c t u r e r and t h e l o c a l i t y .

"G ro u tlo ck * and " S t e e l t y d e "

b r i c k a r e s p e c i a l u n i t s d e v e l o p e d on t h e P a c i f i c C o a s t f o r r e i n f o r c e d b r i c k m a s o n ry an d w h ic h a r e d i f f e r e n t i n d e s i g n and s i z e fro m t h e s o l i d s t a n d a r d f l a t r e c t a n g u l a r b r i c k d e s c rib e d above. C o n c re te b lo c k .

C o n c r e t e b l o c k i s made i n a g r e a t

num ber o f s i z e s and s h a p e s , w i t h b o t h s t a n d a r d and l i g h t ­ w e ig h t a g g re g a te .

The u n i t s s h o u l d c o n fo rm t o A .S .T .M .

D e s i g n a t i o n C 5 5 -3 7 . M o rta r.

M o rta r c o n s i s t s o f c e m e n titio u s m a t e r i a l s

( p o r t l a n d cem ent o r g y p su m ), p l a s t i c i z e r s

( u s u a lly q u ick ­

l i m e p u t t y o r h y d r a t e d l i m e ) , s a n d and w a t e r . P o r t l a n d cem ent s h o u l d c o n fo rm t o A .S .T .M . S p e c i f i ­ c a t i o n C 150-44 (Type I o r Type I I ) . Gypsum s h o u l d c o n fo rm t o A .S .T .M . S p e c i f i c a t i o n 067-44.

8 H. C. Plummer a n d L . I . B e a r d o n , P r i n c i p l e s o f B r i c k E n g i n e e r i n g — Handbook o f D e s i g n , (W a s h in g to n , D . C . : S t r u c t u r a l C la y P r o d u c t s I n s t i t u t e , 1939) p p . 1 1 -3 6

22 Lime f o r u se i n m a s o n ry m o r t a r s h o u ld , i n g e n e r a l , be i n t h e f o rm o f p u t t y . pro cessed h y d ra te s

E x c e p tio n s to t h i s r u l e a r e s p e c i a l l y

(d r y p o w d e r ) , r e c e n t l y d e v e l o p e d , w h ic h

h a v e h i g h p l a s t i c i t y i m m e d i a t e l y a f t e r m ix i n g w i t h w a t e r . O nly h i g h c a l c i u m l im e s h o u l d be u se d i n m o r t a r and g r o u t in S o u th ern C a l i f o r n i a .

H ig h m agnesium ( d o l o m i t i c ) l im e

p ro d u c e s i n f e r i o r m o rta r and sh o u ld n e v e r be u se d . Sand s h o u l d c o n fo rm t o A .S .T .M . S p e c i f i c a t i o n C 144-44 w ith s p e c if ic g ra d in g l i m i t s .

Ocean o r b e a c h sa n d s h o u l d

n e v e r be u s e d b e c a u s e o f t h e w e a k e n in g e f f e c t o f t h e s a l t . M o r t a r , i n o r d e r t o com ply w i t h l o c a l b u i l d i n g c o d e s s h o u l d b e o f t h e f o l l o w i n g p r o p o r t i o n s by v o lu m e :

1 p art

P o r t l a n d c e m e n t , o f w h ic h 1 / 4 p a r t may be h i g h c a l c i u m l im e p u tty ; 3 p a r t s m o rta r sand.

A l l s a n d s h o u l d be p l a c e d i n

t h e m i x e r f i r s t , t h e n t h e cem ent a d d e d an d t h e two m ixed b e fo re a d d in g w a te r .

The l im e s h o u l d t h e n b e a d d e d a n d t h e

w h o le b a t c h m ix e d f o r a t l e a s t f i v e

(5 ) m i n u t e s .

?ifhen

p o s s i b l e t h e m ix e d m o r t a r s h o u l d s t a n d f o r a t l e a s t t h i r t y (3 0) m i n u t e s b e f o r e u s i n g , and s h o u l d be u s e d w i t h i n t w o (2) h o u rs a f t e r m ix in g .

R e te m p e r i n g s h o u l d be done c a r e f u l l y

so a s t o n o t s e g r e g a t e t h e m a t e r i a l s .

No a d m i x t u r e s s h o u l d

be u se d i n r e i n f o r c e d b r i c k m a s o n ry m o r ta r * W a te r u s e d i n m o r t a r s s h o u l d be c l e a r , c l e a n and f i t to d rin k . G ro u t.

G r o u t i s a m i x t u r e o f p o r t l a n d cem en t and

23 s a n d , and so m e tim e s l i m e , t o w h ic h i s a d d e d s u f f i c i e n t w a t e r to. p r o d u c e a c o n s i s t e n c y f o r p o u r i n g w i t h o u t s e g r e g a t i o n o f th e c o n s t i t u e n t s .

The m a t e r i a l s a r e u s u a l l y i n t h e same

p r o p o r t i o n s 8S i n m o r t a r , t h a t i s , one .(1) p a r t p o r t l a n d c em en t a n d t h r e e p a r t s s a n d t o w h ic h may be ad d ed n o t more th a n o n e -fo u rth . (1 /4 ) p a r t lim e . R e in fo rc in g s t e e l .

R e i n f o r c i n g s t e e l s h o u l d be p l a i n

o r d e fo rm e d s t e e l b a r s c o n fo r m in g t o t h e same r e q u i r e m e n t s a s t h a t u se d i n r e i n f o r c i n g c o n c r e t e AL5— 3 9 , A16— 35 o r A160— 3 9 ) .

(A .S .T .M . S p e c i f i c a t i o n

CHAPTER I ¥

DESIGN LOADS M a so n ry s t r u c t u r e s s h o u l d be d e s i g n e d t o s u s t a i n a l l a c t u a l l o a d s and f o r c e s a p p l i e d ; n a m e ly , d e a d l o a d s p l u s l i v e l o a d s , a s w e l l a s h o r i z o n t a l f o r c e s c a u s e d b y w in d p re s s u re o r e a rth q u a k e e f f e c t . I. D e fin itio n .

DEAD LOADS

The d e a d l o a d c o n s i s t s o f t h e w e i g h t o f

t h e a p p r o p r i a t e p o r t i o n o f t h e m a s o n ry s t r u c t u r e and a l l m a t e r i a l f a s te n e d t h e r e t o o r p e rm a n e n tly su p p o rte d th e r e b y . II. D e fin itio n .

LIVE LOADS

L iv e l o a d s i n c l u d e a l l l o a d s o t h e r t h a n

dead lo a d s o r h o r iz o n ta l f o r c e s

(w ind a n d / o r s e i s m i c ) .

They

a r e u s u a l l y assu m ed t o a c t v e r t i c a l l y upon t h e a r e a p r o ­ j e c t e d upon a h o r i z o n t a l p l a n e . D e s i g n L iv e L o a d s .

The l i v e l o a d s u s e d i n d e s i g n

d e p en d on t h e co d e u n d e r w h ic h t h e s t r u c t u r e i s d e s i g n e d , th e d e s i g n e r ’s e s t im a t e s o f th e p a r t i c u l a r s e r v i c e r e q u i r e ­ m e n ts f o r t h e s t r u c t u r e , a n d l o c a l c l i m a t i c c o n d i t i o n s . F l o o r a r e a s u se d f o r s t o r a g e o r f o r h e a v y e q u ip m e n t sh o u ld be d e s ig n e d to s u p p o r t th e a c t u a l lo a d s s u s ta i n e d i f

25 g r e a t e r t h a n minimum r e q u i r e d d e s i g n l i v e l o a d p e r s q u a r e fo o t of flo o r area. Snow l o a d s a r e s e ld o m e n c o u n t e r e d i n m o st p o r t i o n s o f S o u t h e r n C a l i f o r n i a , an d so a r e u s u a l l y n o t i n c l u d e d i n l o c a l C o d e s.

H ow ever, i n m o u n ta i n o u s r e g i o n s w h e re w i n t e r

s n o w f a l l s a r e common, a p p r o p r i a t e i n c r e a s e s i n d e s i g n r o o f l i v e lo a d s a re req u ire d * The L os A n g e le s B u i l d i n g Code s p e c i f i e s t h e d e s i g n l i v e l o a d s shown i n T a b l e I on t h e f o l l o w i n g p a g e . P a r t it i o n lo a d s.

I n a d d it i o n to th e lo a d s i n th e

t a b l e on p a g e 2 6 , room a r e a s o f t h r e e h u n d r e d s q u a r e f e e t o r m ore i n m a n u f a c t u r i n g , w a r e h o u s e , o r o f f i c e b u i l d i n g s s h o u l d be d e s i g n e d t o s u p p o r t a p a r t i t i o n l o a d o f 20 l b s . p e r square f o o t . R e d u c tio n o f l i v e l o a d s .

F o r th e purpose o f d e s ig n ,

t h e a g g r e g a t e l i v e l o a d s u p p o r t e d on v e r t i c a l an d h o r i z o n t a l s t r u c t u r a l m em bers i s commonly r e d u c e d by fro m 5 t o 5 0 $ , d e p e n d in g upon t h e num ber o f f l o o r s s u p p o r t e d o r th e a re a o f ro o f o r f l o o r su p p o rte d A rrangem ent o f l i v e l o a d s .

( f o r c o lu m n s),

( f o r beam s).

S t r u c t u r a l members a r e

u s u a lly d e sig n ed to w ith s ta n d th e g r e a t e s t s t r e s s e s a r i s i n g fro m a n y a r r a n g e m e n t o f l i v e l o a d s .

In th e case o f m u lti­

s p a n s , t h e maximum p o s i t i v e moment i s u s u a l l y c o n s i d e r e d t o

26

TABLE I DESIGN LITE LOADS

P o r tio n o f B u ild in g

L i v e Load (L bs. p e r Sq. F t . )

S lo p e l e s s th a n 3 v e r t i c a l i n 12 h o r i z o n t a l ....................................................... 20 S l o p e n o t l e s s t h a n 3 i n 12 b u t l e s s t h a n 6 i n 12 ♦ ................................................... 15 H o o fs S lo p e n o t l e s s th a n 6 i n 1 2 . 10 A rc h o r dome r o o f s . . . . ................................................... 15 G r e e n h o u s e s , l a t h h o u s e s .............................................................. . . 5 H e s i d e n t i a l ro o m s , s c h o o l c l a s s r o o m s , h o s p i t a l ro o m s • 40 O f f i c e ro o m s, l i b r a r y r e a d i n g ro o m s, c o r n i c e s , r e s t ro o m s, an d a s s e m b ly room s w i t h s l o p i n g o r ste p p ed f l o o r s . 50 . 100 S t a i r w a y s a n d c o r r i d o r s ................ ♦ .......................................... ♦ h e av y s to r a g e in c l u d i n g h e av y a u to m o tiv e t r u c k s . . . • 200 W harves u se d f o r s t o r a g e ....................................... 300 A l l o t h e r p o r t i o n s ............................................................................ 100

27 o o o a r when a l t e r n a t e s p a n s a r e l o a d e d , w i t h a maximum o f th r e e lo ad ed sp a n s.

Maximum n e g a t i v e moment may be co n­

s i d e r e d t o o c c u r when two a d j a c e n t s p a n s a r e l o a d e d and o t h e r s p a n s u n lo ad e d # I n some c a s e s , a r b i t r a r y moment c o e f f i c i e n t s a r e a p p lie d a d v an tag e o u sly #

T h e i r u s e i s l i m i t e d t o c a s e s w h ere

t h e l i v e l o a d s a r e n o t e x c e s s i v e l y g r e a t i n c o m p a r is o n t o th e dead lo a d s

( u s u a l l y a maximum o f t h r e e t i m e s t h e d e a d

l o a d ) a n d w h e r e t h e s p a n s do n o t v a r y g r e a t l y i n l e n g t h (2 0 $ maximum v a r i a n c e i n l e n g t h ) * I I I WIND LOAD A ssu m p tio n s*

W ind p r e s s u r e s a c t i n g on a b u i l d i n g a r e

assu m ed t o be s t a t i c ,

u n i f o r m h o r i z o n t a l l o a d s a c t i n g on a

p r o j e c ti o n o f th e s t r u c t u r e , in c lu d in g th e ro o f ( i f slo p e d ) upon a v e r t i c a l p l a n e #

The g r o s s a r e a o f t h e s i d e o f t h e

b u i l d i n g , i n c l u d i n g a l l o p e n i n g s , s h o u l d be used*

Wind

p r e s s u r e i s assum ed t o a c t i n w a r d l y o r o u t w a r d l y i n any d ire c tio n # D e s i g n w in d l o a d s *

D e s i g n w in d l o a d s v a r y fr o m 15 t o

30 p o u n d s p e r s q u a r e f o o t o f p r o j e c t i o n .

In asm u ch a s h i g h

Ysinds a r e uncommon i n m o s t l o c a l i t i e s i n S o u t h e r n C a l i f o r n i a , an assum ed w in d p r e s s u r e o f 15 p o u n d s p e r s q u a r e f o o t i s u se d f o r t h o s e p o r t i o n s o f t h e b u i l d i n g l e s s t h a n 60 f e e t ?

28 a b o v e g r o u n d a n d 20 p o u n d s p e r s q u a r e f o o t f o r t h o s e p o r t i o n s more t h a n 60 f e e t ab o v e g r o u n d . In c re a s e in d e sig n s t r e s s e s .

A llo w a b le d e s i g n

s t r e s s e s a r e u s u a l l y i n c r e a s e d o n e - t h i r d i f c a u s e d by w in d p r e s s u r e o r by a c o m b i n a t i o n o f w in d p r e s s u r e a n d v e r ti c a l lo a d s. IY . F orces.

EARTHQUAKE LOADS

The e a r t h q u a k e e f f e c t upon e v e r y p o r t i o n o f

a s t r u c t u r e i s assum ed t o be e q u i v a l e n t t o t h e r e a c t i o n r e s u l t i n g fro m a h o r i z o n t a l a c c e l e r a t i o n o f t h e s u p p o r t s . The v a l u e o f t h i s a c c e l e r a t i o n i n t e r m s o f p e r c e n t o f g r a v i t y w h ic h i s u s e d i n d e s i g n i n g , d e p e n d s upon t h e s t r u c t u r a l e le m e n t u n d e r c o n s i d e r a t i o n a n d t h e f o u n d a t i o n c o n d itio n s. I n g e n e r a l , H = CW, w h e re "H" i s e q u a l t o t h e h o r i ­ z o n ta l se ism ic f o r c e , in term s o f p e r c en t o f g r a v i t y ;

"W"

i s e q u a l t o th e dead lo a d p l u s a p o r t i o n o f th e l i v e l o a d , d e p e n d in g on i t s n a t u r e ; and WCW i s t h e s o - c a l l e d s e i s m i c c o e f f i c i e n t , w h ic h v a r i e s u s u a l l y fro m 1 / 1 0 t o 2 / 1 0 . The L os A n g e le s C i t y B u i l d i n g Code s t i p u l a t e s t h a t C i s e q u a l t o 0 . 6 0 d i v i d e d by (N p l u s 4 . 5 ) , w h e re f,Nf* i s t h e nu m ber o f s t o r i e s above t h e s t o r y u n d e r c o n s i d e r a t i o n .

T h is

v a l u e o f MGW i s f o r f l o o r s , r o o f s , colum ns and b r a c i n g i n any

29 s to ry o f a b u ild in g .

T h e r e f o r e , f o r a one s t o r y b u i l d i n g

w ith o r d in a r y l i v e lo a d s , th e h o r i z o n t a l se ism ic f o r c e ,

nH,f,

on a r o o f , c o lu m n , o r s h e a r e le m e n t i s e q u a l t o 0 .1 3 3 t i m e s th e t r i b u t a r y dead lo a d .

F o r t h e f i r s t s t o r y o f a two s t o r y

b u i l d i n g i t i s e q u a l t o 0 .1 0 9 t i m e s t h e t r i b u t a r y d e a d l o a d . F o r e x t e r i o r w a l l s , b e a r i n g p a r t i t i o n s , an d n o n ­ b e a r i n g p a r t i t i o n s o v e r t e n f e e t h i g h , "H* i s e q u a l t o 2 / 1 0 j and f o r p a r a p e t s nHw i s e q u a l t o 1 . 0 . The L os i n g e l e s C o u n ty B u i l d i n g Code an d t h e 1949 U n ifo rm B u i l d i n g Code s p e c i f y t h e above s e i s m i c l o a d s . O t h e r b u i l d i n g c o d e s s p e c i f y c o m p a ra b le v a l u e s . In c re a s e i n d e sig n s t r e s s e s .

A llo w a b le d e s i g n

s t r e s s e s a r e u s u a l l y i n c r e a s e d o n e - t h i r d i f c a u s e d by s e ism iG f o r c e s o r by a c o m b i n a t i o n o f s e i s m i c f o r c e s and v e r tic a l lo a d s.

CHAPTER Y APPLICATION OF LATERAL FORCES IN THE DESIGN OF MASONRY BUILDINGS F o r c o n v en ien c e, l a t e r a l f o r c e s a re a p p lie d a t r o o f and f l o o r l e v e l s .

I n m ost c a s e s , w a lls a r e c o n s id e r e d f u l l y

f i x e d a t f l o o r and c e i l i n g l i n e s and so p o i n t s o f i n f l e c t i o n a r e assum ed t o be a t t h e m i d - p o i n t o f t h e w a l l s e c t i o n . I.

APPLICATION OF LATERAL LOADS

The f i g u r e s b e lo w w i l l i l l u s t r a t e

th e a p p li c a t io n o f

w ind a n d e a r t h q u a k e l o a d s t o a s i n g l e o n e - s t o r y w a l l r u n n i n g a t r i g h t a n g le s to th e l a t e r a l f o r c e s .

Wp * c

x C

+ pvp

=

w (-A _ -h p J

WIND

EARTHQUAKE FIGURE 2

APPLICATION OF LATERAL LOADS

31 Wind l o a d * sq. f t .

I n t h e c a s e o f a w ind l o a d o f "w” l b s . p e r

o f w a l l a r e a , t h e l a t e r a l l o a d p e r l i n e a r f o o t w h ic h

i s c o n s i d e r e d t o a c t a t t h e r o o f l i n e i s e q u a l t o MwM a c t i n g on o n e - h a l f t h e h e i g h t o f t h e w a l l fro m f l o o r t o r o o f p l u s tfwft t i m e s t h e h e i g h t o f t h e p a r a p e t .

So t h e w ind l o a d p e r

l i n e a r f o o t a c t i n g a t t h e t o p p l a t e l i n e i s : Pw = w ( h / 2 + p ) . S e i s m ic l o a d s .

In case o f e a rth q u a k e , th e lo ad p e r

l i n e a r f o o t w h ic h i s c o n s i d e r e d t o a c t a t t h e r o o f l i n e i s e q u a l t o t h e s e i s m i c f a c t o r m u l t i p l i e d by t h e w e i g h t o f o n e h a l f t h e w a l l fro m f l o o r t o r o o f , p l u s t h e s e i s m i c f a c t o r tim e s th e w e ig h t o f th e p a r a p e t .

L e ttin g

eq u al th e

w e i g h t o f t h e w a l l fro m f l o o r t o r o o f l i n e , a n d MWp” t h e w e ig h t o f t h e p a r a p e t , th e e q u a tio n f o r l i n e a r s e ism ic f o r c e "P e q w, a c t i n g a t t h e r o o f l i n e be co m es: P@(^ s G(Ww/ 2 + II.

W p).

DISTRIBUTION OF LATERAL

LOADS TO SHEAR WALLS AND PARTITIONS L a t e r a l l o a d s may be d i s t r i b u t e d t o s h e a r w a l l s by m eans o f (1 ) wooden d i a p h r a g m s ,

(2 ) h o r i z o n t a l t r u s s e s

b r a c i n g s y s t e m ) , o r (3) s t e e l o r c o n c r e t e d i a p h r a g m s .

(rod The

f i r s t two a r e u s e d a l m o s t e x c l u s i v e l y i n m a s o n ry b u i l d i n g s . B u i l d i n g s w i t h wood r o o f d i a p h r a g m s , l i g h t g a g e s t e e l r o o f d e c k i n g , o r h o r i z o n t a l t r u s s e s . D ia p h ra g m s o f wood, s t e e l d e c k i n g and h o r i z o n t a l t r u s s e s h a v e r e l a t i v e l y l i t t l e

32 s t i f f n e s s an d so c a n n o t t a k e t o r s i o n a l moments*

The t o t a l

l a t e r a l lo ad i s , th e r e f o r e d i s t r i b u t e d to th e sh e ar w a lls in acco rd an ce w ith th e t r i b u t a r y a r e a s . I n c a s e o f a w in d l o a d t h e l o a d s on e a c h o f t h e f i v e w a l l s o f t h e b u i l d i n g shown i n p l a n i n F i g u r e 3 , b e lo w a r e g i v e n i n T a b le I I on p a g e 3 3 .

U n ifo rm L oad o f "w* l b / f t

FIGURE 3 DISTRIBUTION OF LATERAL LOADS TO SHEAR WALLS I n th e case o f e a rth q u ak e th e lo a d s to each w a ll a re f o u n d by a d d in g t h e s e i s m i c w e i g h t o f t h e t r i b u t a r y l e n g t h s o f e a c h o f t h e two l o n g i t u d i n a l w a l l s and t h e s e i s m i c w e i g h t o f th e t r i b u t a r y r o o f a r e a s to th e s e is m ic w e ig h t o f each shear w a ll.

S u p p o s e , f o r e x a m p le , t h a t t h e b u i l d i n g shown

i n p l a n above h a s 8 i n c h m a s o n ry w a l l s ft.),

( w e ig h in g 80 I b s / c u .

10 f e e t h i g h , i n c l u d i n g a 2 f o o t p a r a p e t and a r o o f

w e i g h in g 10 l b s / s q . f t .

The u n i f o r m l a t e r a l l o a d o f e a c h

s i d e w a l l , nwM I b s / l i n . f t . ,

i s th e re fo re equal to :

TABLE XI DISTRIBUTION OF WIND LOADS TO SHEAR WALLS (REFER TO FIGURE 3 ) T rib u ta ry area

W a ll

Load t o W a ll

(1 ) . . • (2)

. . . . £

(3 )

. . . .

( * ) . . . . (5 ) . . . .

• • w / 2 (1*2,

^-*2 ^

. • w /2 (Lg + Lg) • • w/ 2 (L g + L ^ )

34

TABLE I I I DISTRIBUTION 0 ? SEISMIC LOADS TO SHEAR WALLS (REFER TO .FIGURE 3)

W all

S e i s m ic Load o f each trib u ta ry le n g th of lo n g itu d in a l w a ll.

(1 )

wL^/E

Wx

irL i

W^ + L^tw + r / 2 )

(2 )

w /2 tl* ^ + 1*2)

WE

i r d . ^ I-V'

.

.

!i i! 3=S3 ^==1’ I. ! i l ■ I E E = ±.

FRONT J c a / e

• . t ■-

...

F L F V A T /O N /&'■** f-O"

*

R O B E R T C. A DO L R E /E C iv il E A j g / n e e r

W A R E H O U S E B U /L D /N G BOR.

6 - E K iQ CO. AT

{ ‘4 9 ^

M Y R O T H F T /C A b

D r o tA / n b y ■

S T .

.

b.A .

R .C . A

C h e c jk e c ? b e // /?. C- A_

J /;e e / /Vo.

A X

■V ••

L .*

/ t u d /n a l : s e c t / o n ■_

long

1

I

I

I j

5; o P o .I s E’v. ll UJ %

i i< 1 UV

%

Io /

AU ■icp tO cT^a., ^ V o p -o * &c. ^

.

/ T “Jgu&nei

Jf 7/GScv>/2"ac

4 - 4 4 /jotveS2 sp 4 0 C/S.

*/’ a) c? ~*ses/s Y - " '" '

-4-.Y „ .__ 4

Minumurf)

/ / a -/arc*/ Gnyc/e: -

i§

1

'T

*\

'

(S' 0

0

k .,

V •

!. * *> ..i

I ■