Instruments for measurement of dynamic stresses (or strains) in temporary steel structures

Publisher’s version / Version de l'éditeur:

Vous avez des questions? Nous pouvons vous aider. Pour communiquer directement avec un auteur, consultez la première page de la revue dans laquelle son article a été publié afin de trouver ses coordonnées. Si vous n’arrivez pas à les repérer, communiquez avec nous à PublicationsArchive-ArchivesPublications@nrc-cnrc.gc.ca.

Questions? Contact the NRC Publications Archive team at

PublicationsArchive-ArchivesPublications@nrc-cnrc.gc.ca. If you wish to email the authors directly, please see the first page of the publication for their contact information.

https://publications-cnrc.canada.ca/fra/droits

L’accès à ce site Web et l’utilisation de son contenu sont assujettis aux conditions présentées dans le site LISEZ CES CONDITIONS ATTENTIVEMENT AVANT D’UTILISER CE SITE WEB.

Building Note (National Research Council of Canada. Division of Building Research), 1950-04-05

READ THESE TERMS AND CONDITIONS CAREFULLY BEFORE USING THIS WEBSITE. https://nrc-publications.canada.ca/eng/copyright

NRC Publications Archive Record / Notice des Archives des publications du CNRC :

https://nrc-publications.canada.ca/eng/view/object/?id=5c1cd4de-208e-4570-86f3-d36ac9f37b0b https://publications-cnrc.canada.ca/fra/voir/objet/?id=5c1cd4de-208e-4570-86f3-d36ac9f37b0b

NRC Publications Archive

Archives des publications du CNRC

This publication could be one of several versions: author’s original, accepted manuscript or the publisher’s version. / La version de cette publication peut être l’une des suivantes : la version prépublication de l’auteur, la version acceptée du manuscrit ou la version de l’éditeur.

Access and use of this website and the material on it are subject to the Terms and Conditions set forth at

Instruments for measurement of dynamic stresses (or strains) in temporary steel structures

Ser TH1 392 no. 7 e. 2

,m

INSTRWEMTS FOR

~ A S ~

OF

E D ~ A M I C STRESSES ~ T

(OR

STRAUS)

IN

TENPORARY STEEL

STRUCTURES

by

W.

R. Schriever

Abstract

Measurement

of

s t r e s s e s in temporary

steel

stnzctures,

such

as girders, struts and p i l e s , used d u r i n g construction of t h e Yonge Street Sub- way a r e being made in co-operatian with t h e

Toronto

T r a n s p o r t a t i o n Commission,

while

stresses

due to dead lead and e a r t h pressure

a r e

static, it is necessary to o b t a i n a continuous s t r a i n

record

by means

of

an

oscillograph t o determine t h e

addi-

t i o n a l dynamic s t r e s s e s due t o

live load,

The ob-

j e c t i v e is to ascertain t h e

maximum

stresses and t h e frequency

of

their

occurrence

in o r d e r

to cam-

p u t e t h e

maximum

l o a d s and their d i s t r i b u t i o n to

determine whether t h e design l o a d s used at present

a r e t o o conservative, S u i t a b l e i n s t r u m e n t s

which

could b e used

f o r such an

investigation a r e des-

c r i b e d a n d

relative merits

o f t h e equipment

a r e

discussed.

Lists of manufacturers

of

s t r a i n

gauges and amplifying and recording equipment

a r e

included,

'

33y535-/

IN

STRWdlX4TS FOR 14EA5URmEi4T

OF

DYNAV!IC STRfiSS&S

(OR

STRAIN) I N THfl TrnPOBARY STZEL STRUCTURES

by

W.

R , Schriever

Introduction

& I

The,construction of the Yonge S t r e e t Subway by t h e

Toronto T r a n s p o r t a t i o n Commission provides an unusual opportunity to i n v e s t i ' g a t e soil a n d foundation conditions in t h e Toronto a r e a and to study some r e l a t e d d e s i g n and construction problems. A orogramme o f co-operative work was therefore suggested by t h e

N a t i o n a l Research Council and the T o r o n t g Transportation Commis-

s i o n , t h e results o f which

will

contribute to the knowledge in this f i e l d

of

engineering in g e n e r a l a n d will be of v a l u e t o t h e

construction i n d u s t r y o f Canada as

well

a s to the Toronto Trans- portation Commission,

Among

the

l i s t o f investigations is t h e measurement o f

stresses in the temporary structures, such as girders, struts and p i l e s used in the

cut-and-cover

method. Measurement of s t r e s s e s in these members is b e i n g c a r r i e d out for

two

purposes:

(1)

A s a check of t h e d e s i - s n of t h e temporary structures, i.e. in o r d e r to compare a c t u a l stresses w i t h allow- a b l e s t r e s s e s .

( 2 ) In o r d e r to d e t e r m i n e t h e e a r t h pressure a c t i n g

on

the sides of the subway excavation under v a r i o u s conditions-

VY%ile the stresses due t o dead l o a d and e a r t h pressure are s t a t i c , t h e s t r e s s e s due t o l i v e l o a d ( s t r e e t c a r a n d motor t r a f f i c ) a r e transient a n d a l s o , to

a

c e r t a i n extent, oscillating, dependins on shock effects of t h e t r a f f i c and the vibration

characteristics

of

t h e d e c k . Therefore, w h i l e it is _sufficient

to measure the s t a t i c stresses periodically b y means o f a mecha-

n i c a l

s t r a i n

gauge, . _{it i s necessary t d o b t a i n}

_a

_{continuous s t r a i n}

record

by means of

an

o s c i l l o g r a p h to determine t h e a d d i t i o n a l

dynamic stresses due to live l o a d w i t h t h e a i m o f f i n d i n g t h e maximum stresses occurring a n d the frequency of t h e i r occurrence,

Only

in this way is it p o s s i b l e to coinputs, from t h e determined maximum stresses, the m a x i m u m l o a d s a n d their distribution and

t h u s to find o u t w h e t h e r t h e d e s i g n l o a d s used

at

p r e s e n t a r e t o o conservative.

F o r t h e measurement o f t h e s t a t i c s t r a i n s , an $-inch

b e i n g

used which

measures t h e

d i s t a n c e ,

or change of

distance, of

t w o small

holes drilled

into the s t e e l . F a r the measurement of

t h e dynamic s t r a i n s , it i s intended to u s e

electrical

gauges;

e i t h e r r n a ~ n e t i c o r resistance

strain

gauges. b i a s n e t i c (or in-

d u c t 2 n c e )

s t r a i n

gauges and

also

unbonded w i r e r e s i s t a n c e s t r a i n

gauges have

a

better long

life

s t a b i l i t y and are more rugged than bonded wire resistance

strain

gauges, a l t h o u g h t h e latter a r e

much lower in c o s t . The o u t p u t of t h e gauges

(or

b a l a n c i n g S r i d g e circuit)

is

u s u a l l y amplified a n d . c a n t h e n be fed into an o s c i l - l o g r a p h recorder, o f which

there

a r e a great

v a r i e t y

o f types.

The question of the rhost s u i t a b l e equipment f o r the present investigation i s a v e r y i m p o r t a n t one. Kuch h e l p f u l

in-

f e n n a t i o n h a s been received by c o r r e s n o n d e n c e and during discussions

o f this problem. Considerable time h a s been s p e n t on a thorough study o f

this

information, which i s b e l i e v e d to be

of

such v a l u e , n o t o n l y

in t h e

present work but a l s o for

future

r e f e r e n c e , t h a t i t

was decided t o p r e p a r e

a

summary, which is now presented

in

this B u i l d i n g Note.

In

view

o f the large expenditure

involved,in

t h e pur- chase of this equipment ( a s - a multichannel instrument

is

requrired)

a n d t h e i m p o r t a n c e o f

the

inst?uments, n o t o n l y for the p r e s e n t work but a l s o f o r o t h e r u s e s in t h e

Division

of Building Research

later

on, t h i s Note

is

s e n t to a l l those

who

contributed to

this

i n f o r m a t i o n

and

to o t h e r i n t e r e s t e d persons. Go:aments and sug-

-

gestions a r e welcomed from readers, as they

will

facilitate the

d e c i s i o n on t h e equipment best suited f o r this work.

In

the mean- t i m e , while this Mote is u n d e r consideration, it is hoped that it w i l l b e p o s s i b l e to

c a r r y out

a

preliminary test with borrowed instruments, so t h a t on the b a s i s of t h e comments received and t h e r e s u l t s of t h e prelimjnary test,

a

well-founded d e c i s i o n will be p o s s i b l e ,

Acknowledgements

The s u b j e c t matter

has

been discussed with a number o f p e o p l e working i n t h i s f i e l d who have contributed

invaluable

i n -

formation, which is gratefully acknowledged. T h e list includes ~e

f

oxlowing:

Kr, H.C,Ross,

Dr.

A,D,Hogg, a n d

Mr.

W,L.Gibson, Structural

Re-

search D e p a r t m e n t ,

H

.Z.P .C,

O n t a r i o , Toronto, O n t ,

14r. "!.J.Turnbull, S o i l s

Division,

U.S. Corps o f ~ngineers, Water-

ways Experiment S t a t i o n , Yicksburg, TJIiss,

Dr.

F .Tit .Lea, 3 u i l d i n g Research S t a t i o n , G a r s t o n ,

G.

VJatf o r d ,

Nr. R.F.Blanks, Research

and Geolopy

Division,

U . 3 . aureau of

Reclamation, Denver,

C o l .

Dr.

V.H.Glanville,

Road

Research

Laboratory,

Harmondsworth,

Kiddlesex, England.

Dr.

F-Aughtie, The Institution of E l e c t r i c a l Engineers, Savoy P l a c e , V i c t o r i a Embankment, London,

!!'.

C. 2, England.

D r . T.W.lpJ,'lodek, Department

of

Resources and Development, O t t a w a ,

Ontario. - :

Dr.

O.V.Ellis

and ICr. P.E.Cavanagh, Ontario Research

Foundation,

T o r o n t o , O n t a r i o

Nr.

D.E.Paasons,

U.S.Bureau

of Standards, Washington, D . C .

F4r.

H

.

B

. S u t h e r l a n d , Dept

.

of Civil

engineer in^, The U n i v e r s i t y ,

Glasgow, Scotland.

J

B.G.Ballard

a n d

Kessrs.

C.F . P a t t e r s o n , F .G .Creed, and

N

.L.

h ~ s t e r s , Division of Radio and

Electrical

E n g i n e e r i n g , National Research C o ! ~ n c i l , Ottawa.

Kessrs. W.J.

Cox,

F,R.Thurston, and

J.P.Uffen,

Division of Mechanical En~ineerins,

National Research

Council, O t t a w a .

and a number

of

a q e n t s of manufacturers of strain measuring and

Measurement of

Stresses

in Beams

and Trusses

o f t h e Temporary

deck in^

Fig.

1 shows t y p i c a l cross-sections

-of the

t w o

main

types af She temporary s t r e e t

d e c k i n g used

d u r i n g subway con- s t r u c t i o n .

F o r t h e strain measurements

on

t h e beams, the p r o -

cedure is a s follows ( a s i m i l a r procedure b e i n ? followed-for the trusses] :

3efore the beam

is

stressed, gauge h o l e s a r e d r i l l e d for

the measurements with the mechanical gauge in s e v e r a l

( u s u a l l y three) cross-sections and z e r o readlngs

are

taken. I n order to d i f f e r e n t i a t e between bending and compression, at least two s t r a h measurements must be o b t a i n e d in e v e r y c r o s s - s e c t i o n , ope near t h e top and the o t h e r

n e a r

the b o t - tom o f the beam in which the s t r e s s e s are to be determined,

For r e a m n s - o f : accessibility, the r e a d i n g s a r e t a k e n

on

the

web.,

near t h e -flanges, ' * -

( 2 ) Aft'er t h e beam

is

'sat i n place, s t r a i n readings a r e taken a t

v s r i o u s

s t a g e s o f c o n s t r u c t i o n , y i e l d i n g bending s t r e s s e s

due to dead weight o f d e c k i n g and compression stresses due to the e a r t h pressure,

which

increases a s e x c a v a t i o n is carried deeper.

( 3 At

a

o o n v e n i e n t time, t h e e l e c t r i c a l gauses f o r t h e measure- nent of t h e additional stresses due to t r a n s i e n t l o a d s

(traffic) a r e a t t a c h e d to the

beam

next to

the

gauge h o l e s

f o r t h e mechanical gauge. Readings w i t h the mechanical

gauge

are

continued p e r i o d i c a l l y at times

of

no traffic. I n

t h i s way, a c b n t i n u ~ u s comparison of t h e

electrical

and the

-mechantcal

gau,yes is ~ o s s i b l e , and t h e - " z e r o

driftw of

resistance w i r e s t r a i n gauqes,

should

this t y p e of e l e c t -

rical gauge be bsed, can pr3ctically b e e l i m i n a t e d . Static Stresses

As already mentioned, a mechanical

strain

gauge ( o r extensometer) of the Berry t y p e [made by F .F . N e t z g e r &L Son, Phil*

d e l p h i a ,

Pa,

) is being u s e d f o r the measurement

of

static s t r e s s e s ,

One

d i v i s i o n on the dial of this gauge, which has

a

base of

8

inches,

corresponds to a s t r a i n o f 1 2 . 5 micro-inches per inch, o r

375

I b .

per square inch stress in s t e e l . Far t e m p e r a t u r e compensation, with e v e r y r e a d i n g a second r e a d i n g is t a k e n on a m i l d steel reference b a r ,

which is put on

the

structural member so

that

it

will

assume

t h e same temperature

as

t h e

member.

Stresses due to T r a f f i c Load

An important question in t h e selection o f the recording equipment is t h e type o f stresses t o b e recorded, i,e, t h e i r

v a r i a t i o n w i t h t i m e ,

The n a t u r e of t h e stresses caused by s t r e e t c a r a n d motor

traffic is

similar

to t h e s t r e s s e s due t o

Live

l o a d

in

r a i l w a y a n d

hishrvay b r i d c e s ,

A

wheel of e i t h e r a _{s t r e e t c a r o r an} automobile p a s s i n 3 o v e r a beam of t h e d e c k i n g causes strains which c o n s i s t

o f a p a r t , caused b y t h e static load of t h e w h e e l c o m i n g

on (and o f f )

and

a superimposed p a r t due to the v i b r a t i o n o f the

beam when excited b y shock effects r e s u l t i n g from the r o u s h n e s s

of

t h e s u r f a c e on which the

wheel

travels. A s a n e x a m ~ l e , a

f i g u r e from

a

paper e n t i t l e d "Description and Analysis af t h e

3 r i d c e Impact T e s t s made by t h e Pennsylvania R a i l r o a d at Chester,

Pa.!'

(proceedings o f Che American

Railway

Engineering -?ssociation,

19k1,

paTe

432)

is reproduced as F i g . 2

in

this Note, showing s t r a i n s in a plate g i r d k r of

5 5

feet LO i n c h e s span measured

in

the middle o f t h e s p a n by means o f m s g n e t i c strain gauTes (inst- ruments No.

1,

2, 3 ,

a n d

4 )

acd a l s o vertical a n d lateral de- f l e c t i o n s measured by instruments of a d i f f e r e n t principle

(instruments

No, 5

and

61

.

These s t r a i n s resulted f r o m the t r a n -

s i e n t load of

a

steam Locomotive t r a v e l l i n ~ at a speed of

46

miles

p e r h o u r .

F o r t h e beams o f t h e temporary subway d e c k i n s , i t is n o t q u i t e c l e a r , at t h e p r e s e n t s t a E e of construction, how impor-

t a n t , i.e, how l a r y e , t h e superimposed v i b r a t i o n a l p m t o f t h e stress is compared w i t h the mean stress as illustrsted in F i g , 2,

In

view of the h i ~ h c o s t of oscillograph e q u i p m e n t , one must a s k , of course, w h e t h e r the vibrztional part o f

the

_{stress is of a}

r n a ~ n i t u d e which would j u s t i f y

more

e x p e n s i v e equipment than

would

b e required'to measure the mean stress. However, it seems t h a t

oscillographs with a low frequency response ( e , % . E s t e r l i n e A n ~ u s

Recording I'iilliameters, r e s p o n s e t i m e 0.5 -1 s e c m d ) are n o t much

lower

i n c o s t than direct-writins oscillographs 7;:ith a medium f r e q u e n c y r e s p o n s e ( e , ? , Brush

Oscillograph,

frequency response c l a i m e d

up

t o 120 c y c l e s per second). T h e r e f o r e , especially with regard t o - o t h e r uses of t h e strain recording equipment l a t e r on, a t y p e o f instrument c o v e s i n s medium frequencies often occurring in structural work would b e

much

p r e f e r a b l e .

An idea o f t h e frequencies to be expected in the beams

o f t h e temporary subway d e c k i n 5 was o b t a i n e d by recording the vi- bration o f one of the beams under traffic by means of a portable Leet Seismographe The result w a s

a

n a t u r a l

f r e q u e n c y of a p p r o x i - m a t e l y

45

c y c l e s p e r second,

P i a ~ n i t u d e .--

of

+-.---

Traffic

Loads

It

has

a l r e a d y

been

mentioned t h a t the

s t r a i n s

are b e i n g

measured

in

several cross-sections o f

a

beam. T h i s i s done b e - cause it is intended not only to find t h e

maximum

stresses but also to determine f r o m t h e s e stresses the maximum traffic l o a d s

t h a t occur and t h e i r distribution. I n this way it w i l l be possible to ascertain whether t h e design Loads used

at

p r e s e n t have been

r e a c h e d or not, i , e , w h e t h e r they s h o u l d be r e t a d n e d

or

reduced in

f u t u r e d e s i ~ n ,

The distribution o f a l o a d acting upon a d e c k i n g beam can b e determined f r o m t h e b e n d i n g moment d i a ~ r a m , found f r o m

stresses. As this can b e done w i t h reasonable accuracy only if

t h e stresses a r e known

i n a

number o f cross-sections, t h e stresses a r e measured at t h e c e n t e r and at the q u a r t e r points o f the b e a m ,

T h i s means a minimum o f six gauge lines f o r a beam in which t h e

strains must b e recarded

in

o r d e r to find simultaneous stress oeaks. Therefore a m e c h a n i c a l oscillogra?h r e c o r d e r is r e q u i r e d . As each c h a n n e l is a p r a c t i c a l l y s e p a r a t e unlt composed o f t h e active gause, the dummy gauge, the balancing bridse and its

power s u p p l y (sometimes c o n t a i n e d

in

t h e amplifier box), t h e

am-

p l i f i e r and t h e oscillograph recorder, t h e h i g h c o s t o f a

six

c h a n n e l

installation

is understandable. Instruments

On t h e f o l l o w i n g ages are lists of a p p r o p r i a t e instru- ments (gauyes and recorders

7

produced by manufacturers of strain

gauzes and amplifying and recording equipment. Also s e t out a r e references on the subject matter. These l i s t s and references

have been

compiled

on Ghe b a s i s o f information kindly s u b m i t t e d b

a

number of those i n t e r e s t e d in

the p r o b l e m

( s e e acknowJledgernents

with

a view t o g i v i n ~ complete information r e g a r d i n g the various

i

available

instruments,

No complete i n f o r m a t i o n can b e given r e g a r d i n g t h e

com-

p a r a t i v e c o s t o f v a r i o u s makes of instruments, a s t h e c o s t o f only

a f e w of them

is

known to the writer. T h e c o s t o f a

six

c h a n n e l

installation w i t h

6

magnetic and

6

balancing

gauges, ( c a l i b r a t i n g

s t a n d e x t r a )

in

Canadian funds, sales t a x and transportation

extra,

is as

follows:

Hathaway (photo~raphic r e c o r d ) Approximately

-

$

6,B00,00

General. Electric ( p h o t o , r e c o r d ) tt

-

€?,6OO,QO

k a r u s h (direct-writin? r e c o r d ) 11

-

8,300,00

Conclusion

Assuming that t h e measurement of t h e v i b r a t i o n part o f

t h e

transient

stresses is desirable, it is thought at the present time that magnetic strain gauges and an oscillograph u s i n q

a

direct t w i t i n g recbrder with

a

frequency response of s o m e w h a t more than

50 c y c l e s p e r second

would

b e the most s u i t a b l e for t h e i n v e s t i - gations described in t h i s Note.

MANUFACTURERS OF

STRAIN GAUGES

De

Forest Scratch Gauge: Baldwin Southwask Division, B a l d w i n

Locomotive Works, P h i l a d e l y h i a 42, Penn, I n d e n t o r Type L o a d

Cell:

No

commercial make.

Bonded

Wire

Resistance Gauge: . SR-4 Gauge

-

2aLdwin Southwzrk ( see

above)

Ru~re-de F o r e s t f n c , , 76 F4assachusetts ~ v e . 3 , Cambridge,

Mass,

DeHaviland P r o p e l l e r s L t d , , H a t f i e l d

Airodrarne, H a r t f o r d s h i r e ,

Zngland,

Unbonded Wire R e s i s t a n c e Gauge: Dr, Roy

W,

Carlson, E n s i n e e r i n g 16aterial.

L a b o r a t o r y , U n i v e r s i t y o f C a l i f o r n i a , 3erkeLey, C a l i f o r n i a .

Statham Laborakories, 9g23 S a n t a I4onica

a l v d . , 3everly H i l l s , California, Magnetic S t r a i n Gauge: Hathaway I n s t r u m e n t Co.,

1315

South

Charkson St,, Denver, Colorado,

West5nghouse Electric Company, P i t t s - burgh, Penn,

G e n e r a l Electric Company, Apparatus D e p t , ,

MANUFACTUREXS

9F

ATulPLIFY1N G A N D RECORIIIIJG EGUIPNKKT

Equipment w i t h pen-and-ink r e c o r d e r s :

3rush Development Co., 3405 P e r k i n s Ave., Cleveland

14,

Ohio. Henry Hughes a n d Son L t d , , 2 Claxton St., London 3YJ0

1.

E n g l a n d . Equipment with galvanometer oscillogrsphs:

Hathaway Instrument Co., 1315 S o u t h C l a r k s o n St., Denver, C o l .

Savase and P a r s o n s Ltd., Vlatford Bypass, Herts., ~ l i ~ . ( u p to 1000 c / s )

i l i a 1 Co Pasadena,

California,

Consolidated Enqineering Corp., 620 I i o r t h Lake A v e . , Pasadena

4 ,

C a l i f o r n i a ,

H e i l a n d

Instrument

Go,, Oenver, C o l o r a d o ,

G e n e r a l X l q c t r i c Company, Apparetus Dept., Schenectady,

N

.

Y o

V e s t i n g h o u s e X l e c t r i c Company, Pittsburgh, Penn, Equipment

~ 5 t h

c a t h o d e r a y oscillo%raphs:

Avirno L t d , , Tauntan,

Somerset,

E n s l a n d ,

( 1 5

c h a n n e l instrument) Southern I n s t r u m e n t s L t d . , F e r n h i l l , Hawley, Camberley, Surrey, E q l a n d .

Mullard Electronic P r o d u c t s , C e n t u r y House, Shaftesbury Avenue,

London

PJ, C

,2, Enyland ,

FurzehiEl L a b o r a t o r i e s

Ltd,

,

3orcham

Wood, Hests,, E n s l a n d , Not S p e c i f i e d :

DeHaviland P r o p e l l e r s L t d . , H a t f i e l d Aerodrome, Hertfordshire,

Eng.

Trimount I n s t r m e n t Co.,

37

TI, Van Buren St,, Chicago 5,lllinois (arnglif

iers

only)

REFERENCES

S o c i e t y

for

Experimental

Stress Analysis

-

Proceedin~s,

Addison

-

Wesley Press, I n c , , Cambridge, Kass,

(Published semi-annually s i n c e

1943.

Numerous r e n i a r t s o f studies of d

namic

stresses, a n d references to most o f the o t h e r l i t e r a - t u r e

5

.

Dobie, W , 3 , and

(Published Isaac,

P .C

.G

.

,

in England) " E l e c t r i c Resistance Strain

American Society of T e s t i n g Ykterials, p a n e l of papers on dynamic t e s t i n q presented at

an

A,S .T.M. meeting in San Francisco in October

1949

'rA survey o f pick-ups f o r Dynamic P h y s i c a l P."lasurementsT\ t T 3 e l e c t i o n o f Recording Equipment f o r Dynamic Testingn,7vAnalysis a n d

I n t ~ r -

pretation of Dynamic Recordst7,

and

nExarnples o f Dynamic

Testing

in

t h e F i e l d of Naterials and structure^^^^

A r n o l d , R

, N o ,

paper c o n t a i n i n g description of

DeForest

Scratch Gauge ,,

Proceedings o f the Institution o f Mechanical E n q i n e e r s ,

Vol,

137?

page 2 2 5 .

Redshaw, S.C., J o u r n a l of t h e

Royal

Aeronautical S o c i e t y ,

Vol,

5 0 ,

p . 568-612, August

1946

-

paper on t h e subject of resistance s t r a i n

gauges.

3aLdwin Southwark D i v i s i o n of the aaldwin Locomotive Works, Philadelphia,

Pa.,

SR-4 Kews L e t t e r s concernin-? t h e s ~ b j e c t of Testing, V o l ,

11,

No, 1 & 11, Aug, & S e p t ,

1945.

y 7 S t a b i l i t y o f S t r a i n Gauzestband "Apparatus

for

Recording S t r a i n f T , and o t h e r s ,

Sansom,

T o

B,

,

y t R e s i s t a n c e

Strain

Gauges, Methods

of

attachment a n d

their

r e l a t i o n s h i p to Zero Creepfr a

Electrical Review ( ~ r i t ,), 1k5

(3736)

July 1, 19.49-

Tannahill, A ,

L o ,

"Application of E l e c t r i c a l Resistance S t r a i n Gaugesn The E n g i n e e r ( ~ r i t , ) pp,

630-633,

_{June 10,}

1949,

( A t t a c h m e n t

of

gauges f o r u s e

in

air and under w a t e r

-

t w o separate techniques, d e s c r i b e d and illustrated s t e p by s t e p ) .

R o o d b e r ~ , A . , Howe,

E.D.,

and Yark, B.,

"The

S t a b i l i t y of SR-l+ E l e c t r i c a l Strain

Gaugds

and Nethods of

Their

W a t e r p r o o f i n g and-Protection'in

Field

Servzcev\ Am. Sac,

of

Mechanical E n g i n e e r s , P a p e r Ao,

&7-A-

1 2 0 ,

I9b9.

American Railway E n g i n e e r i n g A s s o c i a t i o n , r ' D e s c r i p t i o n and Analysis of the B r i d g e Impact T e s t s made by the

Fennsylvania

Railroad of C h e s t e r ,

Pa.

!rProceedings, V o l . 42, pp,

393-483

194.1. ( I n s t r u m e n t s described

Van

Eenam,

N.,

U . S .

3ureau

o f

Public

Roads,

nLive

Load

Stress

Measure-

ments

on

t h e Fort

Loudon aridge,Pennsylvaniatt. Report

presented to

. . the Hi5hway

Research

Board,

December

1949.

Lamble, T.

H.,

and

Gill,

S . S . ! "The Measurement o f

S t r a i n v .

Bulletin of the Liverpool E n q i n e e r ~ n g Society.

The Institution of Electrical Engineers ( B r i t . ) , Ninutes of a discussion on "The aleetrical Measurement

of

S t r a i n T r . Meeting h e l d on ivov,

TORONTO TRANSPORTATION COMMISSION

-

RAPID TRANSIT DEPARTMEWT

] B E A M CONSTRUCTIOH