The effect of initial displacement of the center support on the buckling of a column continuous over three supports

MISSING IMAGE

Material Information

Title:
The effect of initial displacement of the center support on the buckling of a column continuous over three supports
Series Title:
NACA WR
Alternate Title:
NACA wartime reports
Physical Description:
5, 10 p. : ill. ; 28 cm.
Language:
English
Creator:
Lundquist, Eugene E
Kotanchik, Joseph N
Langley Aeronautical Laboratory
United States -- National Advisory Committee for Aeronautics
Publisher:
Langley Memorial Aeronautical Laboratory
Place of Publication:
Langley Field, VA
Publication Date:

Subjects

Subjects / Keywords:
Buckling (Mechanics)   ( lcsh )
Aerodynamics -- Research   ( lcsh )
Genre:
federal government publication   ( marcgt )
bibliography   ( marcgt )
technical report   ( marcgt )
non-fiction   ( marcgt )

Notes

Summary:
Summary: A long column continuous over three supports was tested to determine its critical load when the center support was given varying amounts of initial displacement. During each test the middle support was hinged so as to be free to move parallel to the column axis during buckling.
Bibliography:
Includes bibliographic references (p. 5).
Statement of Responsibility:
by Eugene E. Lundquist and Joseph N. Kotanchik.
General Note:
"Originally issued November 1940 as Advance Confidential Report."
General Note:
"NACA WARTIME REPORTS are reprints of papers originally issued to provide rapid distribution of advance research results to an authorized group requiring them for the war effort. They were previously held under a security status but are now unclassified. Some of these reports were not technically edited. All have been reproduced without change in order to expedite general distribution."

Record Information

Source Institution:
University of Florida
Rights Management:
All applicable rights reserved by the source institution and holding location.
Resource Identifier:
aleph - 003804949
oclc - 123900769
System ID:
AA00009473:00001


This item is only available as the following downloads:


Full Text







$JTIOKNAL ADVISORY COMMITTEE FOR AERONAUTICS

7F*



I TIME REPORT
.. ORIGINALLY ISSUED
November 1940 as
Advance. Confidential Report

Mi3 EFFECT OF MITIAL DISPLACEHiT OF THE CENTER SUPPORT
4 THE: WClAUG OF A COIDM CCNTNUOuS OVER THREE-SUPPORTS
By Eugene E. Lndaquist and Joseph N. Kotanchik

: Langley Memorial Aeronautical Laboratory
l:^..": Langley Field, Va.






.......






WASHINGTON

-liA F epvints -of- papers originally sued to provide rapid distribution of
.... ..ts.. d group-requLring thepn for the war effort. They were proe-
it but e now unclasified. ome of these reports were not tech-
;re P|rMw theiout chage in o der to expedite general distribution.

















































S
i
















t
"Ci


























I*













TE.L EJFZCT CG_ II::TIAL DISPLGAC::E::T C 'x-i: 3-'ER ,P P'?

OLT TEE 3UCILLiC- 0 CODLU'I OITLI' T:yr- r L- 2r.EE S:-PFOrPTS

S ".-LuS.:t.o 2. LundJ.iuist ar.d LJo0-'ph 1. o0 anch'hik


SUX.-.AY


A .. .. ?ClU-.i ccnt :.uc us ,-c ;:r thr suippOrt .r.s
t J t-- .r d tL.ri. -. it crit icl;.1 i.jd hben th: con er su.n-
port .;L'-: i-:. v.r'.-.ng ei .our-.c o: :.-.it.i -i i:p1n l nc: t.
Du i:' .; c-.c t. t t.e idfia.' i s-:pp rt w.s hi.:,-,. so r.n to to
free to :-ove para-lel to the cciinL axis :M'tinr bucklin'.

T'-e cr iical loa-s predicted front ic.ad-d.flection
resa i.-L ? vre2 d.ifferet for -~c'T u.in-er ana lo-'-ur s L:a:- .
The ln'ge.- :--. ict3c' critical lo-& ir. ea c. t-'+ as for
the "S '.. ti'L t L :cl-C 1 .r. ,, 'f, 1 C t :. a' .;', r. '
initial efi ctic c r o1f thce r.:r a .. trn? r-. a!i r .r:-
d icted cr. itical lorba in ec'L t: s t *Ls fr,r the s:T -i t'.at,
on. T ue.:ling, ': f .ect l .:o 0 s to a;rai :..t : out and rc-.'crsc
t i. t :it 1 .Qcfl e'-. i n clur'.o rf tvc SrL a T iL :LC c O'u -cr.-a-
tio-s l cr ,.ri'd' Es of wh. t cr th' in til a cf l action
of tL1,-) ceri:t su'c, art 'Js-- t3 ith ri .ht or th.1 left.

The if c: r :-. c:-. t E :. w 1n the.. -.-it ic l l: -.T ': re ictod
for the ui-p:r and lo: ,r s!.& is prc o:- i onal to toh in-
itial J.efl ct ion jf tt ccntL-: sti, (ort. Th.e &. 'ff r :* r.co
noted i:" .3:?. tests i. :c t rr, i:n terms o" .:rr.)rs pr,,mr-
ami :ibl: in cra :ct icr.l I i g.- Th. fact that a dif'T r:.ricc
oxi. ts3 ir t'.o pr.)dict,3d cri ;ic-il l-cads sv.'j:.sts t.:-t a
in1. c r.-. i in tc sinr. le a;r 1 ic.-.ticn of the Scut.:wcrl mir thod
as ; r.23 Lteo. in r ofcren.r .2, ,or a moi.'ifie J in r fcre: cc
1, can rc zult in c fi nit r a:-.. m .enarurcbl.: crrri '.

Th.c av-r.-:r of t'.: prziict :,i criticci lo-.ds for t-.:
upper orni.- loeor spons iat .orr cor-c2t t. r. -ither. pre-
dicted critic.--. io.d. This cbs.r-.-atio- s'u_.- sts t:hr-t
whatever is c u-.li:: c ) prec ictod criti .! o.1 ld to be
hih i.. oe span alc-o caus,:, the n- :dicta. critical loa!
to bc low in th2 other s'an.

WhL t.vor.z-e of t h prc'dict od critical lo.c.s for the
upper nnd lower sp.ns i rcluccl by initial.:. displacomont
of the ccntor support *.nd thiz reduction tan7.!s to increase
with h. c.rb-c'lutc valuc of 'h- initial .iispi-cLm~ut. In













thosc tasts the reduction ii the average critical load
ca::se. by i..i .ial i jt.1l... em.s::t of the center sv.pport is
ve:' small. *.is -f ct i..diates t..at t.ie effect of cur-
vature duc to te :litg. on critical laO.. for the con-
rression fla. ;s :.at. ria'. of .a cx boam i3 probably snall
and can to c e..,ictd in enDgi:.crin-; .esign.





In the c'J.rac of a : c i sc.s;.-ion .;ith It. "hol. Carl F.
Gr-cne, Air cort:- i-i.o Off-'cer ;ith i-.e I.LCA, of the
effect of curva.ture b..- o b:-,naing on t' r critical loo..
for t'e cc ;r.' c. i nL fl n,'c r.:a erie. of ;,a oax bc.', it :tras
de-cided. tc t st a Ir; r ilmnn continuous. over t:lre, sup-
ports "vith t. -- i.. :.'..:ir1; iv.a an iriti .l dis.lacc-
mi nt to r :.r'c ..t t'o cr- ct'ur of C'nJ.i::r in a snre 3ses -
s3i: win,. in ti'c t+ st ". .' i .i dl E surpi:,ort vI. hing:cad so
as to ob fro. + :. -i'.- ar ll 1 to thc c l..:n a.ias d1.rin,
'u lin It \: 3s cC.n i tc rc..' t this :."e of su.ip-.ort
' oul b co a r acs nabi t --pro ::. t ion to t:c t.;pc of sv- oi'rt
p.ro-:. i i d b -- t'-c. ri.'E of c1.c rl:. bDc.r..


A??A.AATUS Ail ;:3,HOD


Tl-: c:zt -.O-u.: i. shon n in figur-r 1, L, and 3. A
aia -rafina.t i ko tch of thc to .. ias rho .n in. ricuro 4.

T:-. Ion; c conti u n.s cur ur;-lr,-1 in. t.3 costss c.Es a
3/ -i c lr:-.I .i. : Lt r z to l :.r 67-7.'.5 inch bot;'-:c n t..c end
::.:i" e.;'.,c The r'.i ilL of th. c ntin'.ious cclumn *"'-.r sup-
porte l tc'-- .ll" ';-b a stiff s --'ut 1 -?/SB in'ics lcn.'r. On.
o.... of his s r'ut u.z in.-joined to- the c cnt:iatcus cclu:mn
at its :-ii c. hc nxi ef-j this i"n joint 'a .s ~o'. to
int zrscr r.-'.:is cf '-nc col "'-rn :. .* to re:-.c 'o 'ny p)s-
S11i, .Iv rs c effects f an cc n:'t.r ic pin joint 't this
1 -c-C i -.',. I T.' o 'h. r c.:-J cf t-he l.:er.'.1 su- crt in- strut
.:.7 i.- -:i.c- t- a riid. su'p)ort ir., structure in sch
. '.r..' th.t r..G nid le o-f the ccnt;'.-,:-u colun.- could not
dcflzct ncr-.a.l to tho initial deflcctic-.

Du-rin; rch cest deflection r-din;.-.s n.t the midle
of e-.ch sp:.: ore.'c taker.. from a fixed r fcrcncc point o."
the slotted. tonsior rod nf the t-est1ing n-c.ine *.-ith an
insio Microrotcr crlinor roa,4ir. to thousands of an













inch. The micrometer caliper and its extension bar are
not shoe-in in figures 1, 2, and F.

In each test the specimen was loaded through the
same range of leads. Therefore the sn.all errors in the
loa,.s indicated by the testing machine cancel then com-
paring the results of one test with the rr-sults cf an-
it'.er test.


RE SUL T S


-h-2 loaJ.- reflection reading '-l.ken duriia, thick ia-:es-
Li..ation are .i'v-l in cabl is ~- to 711 aiclu' ive. The-se
date. .arce .lotted ir fir-.-res 5 to 11 inclusi0,e, from which h
the opr .Ict3 6 loads are obtainei&-in the mrnn'er of refer-
ence 1. Th:sc or-dicta3c lo0.is are listed in table VIII.
In figure 12 Itl.: --iffer nce bet .i:on the rr .'.ct criti-
cal loC., for tlh uprper and lowe-r san is plotted gaciust
thu initial ifl c tion of the c-antr su-port. In filj.rc
13 the avore.,:c va.luc of the prCiicted. critic-.1 leads is
plott--:. .n ainst the initial r efl -ction of tn' cc.itr sunp-
port.

In each test b'ck .LI occu'rr' *it- i-flection to the
right in the upp:-r span an. :'.cflo t io to thr. loft in the
lower snp.i. TCh test for whichc h Tec initial ceflcction of
the ceatcr support iwas 0.749 inch :as !.c 1c..t tc0t par-
forc :e1. In C is -ct t"h: c l w s 'lo.c-.c d truee ion
and t.he maximum ion.' ,rzs found to Le .3910 pour.s.


CCiTCLULI::G LISUS~"'~S


InspeZZtion of table VIIT sh.:s that the critic..l
lo..ads pro.dicte'O from loai- c-lflection rc.e.dings -.ere -Jiffor-
ont for the upi.cr ..i lo:ror spo.nr .. Thku Li.ar er predicted!
critic-.l lord in c'.ch test ,S s fol t.o ?p,x.n thrt, on
buckling, ,-lfloctec so .as to dcecn tl..:- iaiticl deflection
curve of the sp:an anr the s;c.-.llr zroe.ict cried c lor.d
in ar.ch tacot was for the sn..r tht'.., on buckling, de fl cted.
so as to s ra i:ht n out 2an. rcv-rzc the initial election
curve cf ".61i spanr. These observ.".tions h..ld rcgar-'lcss of
whether tie initial deflection of the ccnitor support was
to the right or the left.













Figure 12 sho.si +.h.:.- the .Ziffer-ncc betwo.n th. crit-
ic..1l -lc *.r ic":.c for *;he upp:.r anc.. lo--icr s.,r-.ns is iro-
portionU .l tc th-I. init ,- 1 c. f 12 ion of the center sup.pcrt.
The i'.ff-rc:.c rctad in scsea tes ts i.s -ot lar.go in torms
of errors IpcrmiEsibol in pr-.ctic-.l dotsig.. The fact that
t lit-'_i rz. c c ,'i ts i. th. r- ,i'...J.rictd" critical lor-i's sug-
gc-st th.,' i ..cisc'i o i. si.gl -. Crlic.nt ion cf the
Sou"i/c1 -zoth,- ac .rr -er.5tc.. i. re -crnce 2 or as nr.c i-
fic- i:- ru:f c o..c; 1, c.* rusu,~- i- : fini ce and z:.a'Lsur oblc
errors. It t. .or for, .. ir -.:bl to st'-iy the ceuse of
the cLff-oroc. in h n .::ro icte critical loa-.d3 in order to
d.t'r...ioa 1: .hct r or n.ot hLu arror coul'L over bocoo large
c:-non-.i'h to be of ra.-icral in :.ri'tainco in c.: i: c arirn appli-
c at io:s,

o .n test tha.t .ns .urri-. to ,cs tructi on, the
follc i c .-. -.L w2L r.: ob z; :i..e :

.r xc.i:t:C crit, :-.l loc..., u.poer zpr.-.: 9" lb

Froa'.Lct ''. critical loI loI.'cr s6 La 3757 lb

Avcrz.a. pr iri:4.. criticni lorn. 3S2? lb

::. .::i..u li i- .oc tr ,ctt: o-. t st : 10, Ib

Front t"e.e.e rc .. ts I Is conc --,id -nc*.t the average of the
creolicte$. critical .1:-ds for t.- upper and lower spahis is
nr, co--:-ect than cil.:r re~dic ..te. 3 t icnl lo.c. T':is
ocbervea tIo-n s-; c st t'.h t -- t r.at-"c r is c nuszing the predict-
ed z 'iti za load to ba h i--:h on- sanr. also causes the
prl...ict: ._ critical i -:.aI co be lo,- in the other span.

It is concluded from 1.i-',re 13 that the averseg3 value
of the .:rre ict:d cri'uial o10a. is r iduce. by initial dis-
rplace 0a of the zeater supper -r. this reduction tends
to i.cr aie :.ith tia abs bil.tc v -:r-.2 of the initial dlio-
plac:c&,cat. I- tLese bests t'.e *c-*i tion in the average
_.re*icte- *. critical load caused b~' initial Ldiplj..cement of
the ce-.ter support ii ho jcver, very SL-all. Thi fact
indi.:-at?s >a t.i-. effect of cIrvatPr. o du- to bending on
the- critical i.lad for the compression fla.:ge matcri7il of
a b'o: b -,..t is prcb-ab].y s:-,.21 ani can oc nc-leacted in on-
giaccering design.

Tia fact t--at .u -ativ, initial displacement of the
conto. -.1'or_ .r Pv loier overajo predicted critical loads
than corr or. oit in. pociti.-:: initial clisl0acements iat'i-










5


catccr that t.ur ma;' hv. CaQ 2.c]: of perfect tyrnmctr:
and ccntrc.1 lo.aiiu.:. T.?r f:.c tih :, on bv..-kli:.;, t".e un-
per span a :.a,-".z d tflcct to .he rl.-t a .:. t'. l. .- r s .?:?3
to the left scours to su-.jrrt thc 3.;.1 .c. i'rn t'hat Du1:'f :t
sym..:otry ar.:_ cer.tral lo.d-rins, Wure n. t ac._icvcl.

It is possible that a u if'.: r c:c in the lricdin. c:rn-
diticns in the' t-..o -p when t:.c :-.ter c: o .o t s is i-
tially _.oflcZt:-- ec.u- cs To.c prcdi.:t *d ? -ri c-.l loa;. for
the.a tuo F E.ans r di ffr. Ger. .inl;,y c. iif:c r,-:ncc_ o i:-v.:
e .t.3 w:."n d flicticn, on bucl.11 in.:, -. c op r. the l iti.al
dafloc-.icn :'.*.'c o*f on; aSf. n .a;c' str i :'tcns ct.t a.a re-
ver: c t.c it: i- ie! 'efiection c-.r-r:, cf tac cth.:r Zoan.
Insup cticn of tablc: II o VII iinc i'..-v z c. s t..at for
the mr-,:: i-ncr cnr.t of lo.d F-? he l7'-Ocr ir.crOm.nht
of defle r y-T is -..vway. s obt.. lc-1 .. fC e..c-
tion, onr obu :-i._j, 6.a;e-:ns t.:-, initial t'fl.-, ion .:-rvec
of :.(e s :n. The :-istc ce .- di furant i::c-e.7*.:nt of
i -ficctic. f r ,. .c :i.cr i-.t :f lo '.. c n nl --.:- n 2,
Stiff rec.:c iy t h.:; i.. in, cc :".ii i o. r c a-c L-.. -.


L- l.ey c :O rial A..rcnrau cal t- c.tor"',
:.cticna! A,:*vi.'- j ./ C mru itt c f-,_' A o:' o a ti"s,
L .:-i lc Fic i., ,' .







1. L- c. :i t, sU.;:orv. -,. -n -.*- i-i An al tsi of S< cri-

T.:. "-:. 'j58, .TACA, i C38.

2. South ll, P.. .: On t:n Pn.l 3si:-7 c f I;:..' incnt .1
Cbs rvations inr FrbL e-; uf a1:.. tic Stcbilit y.
Froc., Ro.:-:' 1 Se. A, vo'.. 135, 19.2, :. 6C1-r16.










Tables 1,2,3


TABLE I

Load-Deflection Data
Initial Deflection at Center Support 0 inches.


Upper Span Lower Span
P PI = 3000 lb. PI = 3000 lb.
yl = 18.191 In. 71 = 18.114 In.
(lb)
y y-71 P-PI Y-Yl y Y-y P-P, Y-y
(5) (in.) (1bj T (in.) (in.) (lb) P-
(in)lb) (in/ib)

3000 18.191 0 0 18.114 0 0
3200 18.204 .013 200 0.0000650 18.104 -.010 200 -0.0000500
3400 18.224 .033 400 .0000825 18.083 -.031 400 .0000775
3500 18.244 .053 500 .0001060 18.064 -.050 500 .0001000
3600 18.275 .084 600 .0001400 18.031 -.083 600 .0001383
3700 18.350 .159 700 .0002271 17.954 -.160 700oo .0002286
3750 18.451 .260 750 .0003467 17.854 -.260 750 .0003467

TABLE II
Load-Deflection Data
Initial Deflection at Center Support 0.453 Inches.


I--_
Upper Span Lower Span
P1 = 3000 lb. Pl = 3000 lb.
Yl = 18.556 in. Yl = 18.470 in.
(lb) --------- -- ---------------
y Y-yj P-P1 y^. y y-Y' P-PI Y-h
(in.) (in.) (lb) P-s (in.) (in.) (lb) TI1
(In/lb) (In/lb)

3000 18.556 0 0 18.470 0 0
3200 18.576 .020 200 0.0001000 18.461 -.009 200 -0.0000450
3400 18.605 .049 400 .0001225 18.444 -.026 400 -.0000650
3500 18.635 .079 500 .0001580 18.424 .046 500 -.0000920
3600 18.677 .121 600 .0002017 18.585 -.085 600 -.0001417
3700 18.796 .240 700 .0003429 18.269 -.201 700 -.0002871

TABLE III
Load-Deflection Data
Initial Deflection at Center Support -0.447 inches.



Upper Span Lower Span
P1 = 3000 lb P1 = 3000 lb
Sy1 = 17.853 In. yl = 17.741 in.
(lb) ----------- ----
y Y-71 P-PI Y-y y Y-y1 P-PI 7-y
{(in.) (in.) (lb) ,1 (in.) (in.) (lb) X-
(In/lb) (in/lb)

3000 17.833 0 0 17.741 0 0
3200 17.843 .010 200 0.0000500 17.724 -.017 200 -0.0000850
3400 17.863 .030 400 .0000750 17.691 -.050 400 -.0001250
3500 17.885 .052 500 .0001040 17.660 -.081 500 -.0001620
3600 17.933 .100 600 .0001667 17.607. -.134 600 -.0002233
3650 17.985 .152 650 .0002338 17.547 -.194 650 -.0002985
____ __ _-


IAmA






IAOA


TABLE IV
Load-Deflection Data
Initial Deflection at Center Support 0.749 inches.


Upper Span Lower Span
P1 = 3000 lb. -1 = 3000 lb.
71 = 18,742 in. Yl = 18.662 in.
"(l b )
y Y-Yi P-Pj Y_-l y y Y-1 y1
(in.) (in.) (lb) T b) (in.) (in.) (lb)
I___irk/__b)_I_ (in/ib)

3000 18.742 0 0 18.662 0 0
3200 18.757 .015 200 0.0000750 18.663 +.001 200 +0.0000050
3400 18.782 .040 400 .0001000 18.656 -.006 400 -.0000150
3500 18.811 .069 500 .0001380 18.647 -.015 500 -.0000300
3700 18.901 .159 700 .0002271 18.575 -.087 700 -.0001243



TABLE V
Load-Deflection Data
Initial Deflection at Center Support -0.747 inches.




Upper Span Lower Span
P1 = 3000 lb. PI = 3000 lb.
Yl = 17.605 in. yl = 17.490 in.
(lb) -- -
y y-yi P-1 Y y -y y-1
(in.") (in.) (lb (nb) (in.) (in.) (lb)b)

3000 17.605 0 0 17.490 0 0
3200 17.614 .009 200 0.0000450 17.463 -.027 200 -0.0001350
3400 17.635 -030 400 .0000750 17.422 -.068 400 .0001700
3500 17.662 .057 590 .0001140 17.381 -.109 500 -.0002180
3600 17.719 .114 600 .0001900 17.309 -.181 600 -.0003017
3650 17.818 .213 650 .0003277 17.226 -.264 650 -.000406?


TABLE VI
Load-Deflection Data
Initial Deflection at Center Support 1.013 inches.



Upper Span Lower Span
PI = 3000 lb. Pl = 3000 lb.
P yl = 19.010 in. yl = 18.902 In.

(lb) y y-y1 P-PI1 ^ y y-y1 P-P1 -1
(in.) (in.) (lb) (n/1b) (b (in/lb)

3000 19.010 0 0 18.902 0 0
3200 19.037 .027 200 0.0001350 18.897 -.005 200 -0.0000250
3400 19.080 .070 400 .0001750 18.880 -.022 400 -.0000550
3500 19.111 .101 500 .0002020 18.856 -.046 500 -.0000920
3600 19.169 .159 600 .0002650 18.804 -.098 600 -.0001633
3650 19.254 .244 650 .0003754 18.739 -.163 650 -.0002508


Tables 4,5,6








Tables 7,8


TABLE VII
Load-Deflection Data
Initial Deflection at Center Support -1.020 inches.


TABLE VIII,

Summary of Critical Loads
Predicted From Load-Deflection Data.


Initial Pcr P Pr Pc Per
Deflection r
at Center Upper Lower Average Upper Lower
Support Span Span Span Span
(in.) (lb) (Ib) (lb) (Ib)

0 3858 3850 3854 8
.453 3868" 3789" 3829 79
-.447 3773"' 3830* 3802 -57

.749 3897' 3757*" 3827 140
-.747 37270" 3831* 3779 -104
1.013 3890" 3753"" 3812 157
-1.020 3737" 3872= 3805 -135



*Deflected on buckling so as to deepen the initial deflection
curve of the span.
**Deflected on buc.'ling so as to straighten out and reverse the
initial deflection curve of the span.


Upper Span Lower Span
P1 = 3000 lb. PI = 3000 lb.
p Yl = 17.393 in. 71 = 17.274 in.

(lb) y Y-Yl P-P1 -Yl y Y-Yl P-P1 Y-y1
(lb(in.) (in.) (b (in.) (in.) (lb) P-P
(in/lb) (I/l1L)

3000 17.393 0 0 17.274 0 0
3200 17.396 .003 200 0.0000150 17.241 -.033 200 -0.0001650
3400 17.416 .025 400 .0000575 17.193 -.081 400 -.0002025
3500 17.450 .057 500 .0001140 17.150 -.124 500 -.0002480
3600 17.499 .106 600 .0001767 17.075 -.199 600 -.0003317
3650 17.566 -173 650 .0002662 16.996 -.278 650 -.0004277
-- -L ..-.-.


NAGA








Fig. 1


Figure 1.- Test
@at-
up showing col-
umm with ini-
tial deflection
at center @up-
port of 0.749
inch before
loading.


300 000-POUND
HYDRAULIC
COMPRESSION
r TESTING
MACHINE


KLCA







Fig.2


300 000-POUND
HYDRAULIC
COMPRESSION
TESTING
MACHINE







Figure 2.- Test

up showing col-
umn with ini-
tial deflection I '
at center sup-
port of 0.749
inch approach- i .
ing critical
load.


NALCA







Fig.3


WACA


Figure 3.- Test
set-
up showing col-
umn with ini-
tial deflection
at center sup-
port of 0.749
inch at, or
past, maximum
load.


300 000 -POUND
HYDRAULIC
COMPRESSION
TESTING
MACHINE








Fig.4.


Positive deflection


Reference !
line




1/ h
Deflection
readings
taken at thiq ~ ----- --
point in Pin Rig-i
upper span joints supporting ,
Initial I structure 12 h
deflec- '
I tion at
ce Center
support- s support
S- Stiff
Deflection i / strut 3/-
readings


taken at
point in
lower spa


Upper
upiort

F- .


I h
i


tn ---- -- -- ---
t.q -
Lfl -


h = /


Position with Low,.r
no deflecticn support


Figure 4.- Diagrammatic sketch of test spLcimtn.


in.


NACA


L.











NACA C:

--4 C o 0
a* d -H 0 m. -0


i Ci -14 -P
o 0c C L -1-1
-r-4 **- -M M-

10 4- 0 0 0 0
0 -H r -.
0 & 4.1 0. c
C : 0 0 3 t
S"-4 tb L 'in
i3 P .--1 r-- -H
*r4 -, *rI( OU) 0
F-C '0 d. -P *-ri


4P
-4







C-0

c I
-P

on9'

cdi'


0 CD
C
0 0
* H


,r-4 4
-0 -)

c o








0-

C.r
140




-,--)


O ---.



I
a





bfi
0 -i-
CzO


i

La

S14

*i-


- -A _- -




---C-----



t2 -


I \














O0
8









O\
0 ---- ___ o ___--------


Figs.5,7,11.







NACA Figs.6,8,9,10.






0 0 *
\0 1
ow o
rr -,



~ r--I


o \ o
a
-\0 o

-- ^-- i._ j -------. \ ^ ,.





J _\ \ -, -



\ 1 0
--- 0 r C1


















C40 C.) co C )


\, ..--. \\ .






*0

l G C :; K -





0 4
0-- q- -0











to-, 0 C" 0












P-1 3 r








Figs.12,13.


Figure 12.-


oo-- --- -



00 --- ___0






-.8 -4 0 4 a
Iniffi.' oefiec on of ce-te- .sppor, n

Variation of difference in predicted critical
load with initial deflection of the center
support.


-.8 -.4 0 .4 .8
Initlia ce.,ection oa, center supoort, it
Figure 13.- Variation of average predicted critical load
with initial deflection of center support.


NACA















'4


r






































I>




UNIVERSITY OF FLORIDA

3 12 2 08106476ll 1tm






UNIVERSITY OF FLORIDA
DOCUMENTS DEPARTMENT
120 MARSTON SCIENCE LIBRARY
P.O. BOX 117011
GAINESVILLE, FL 32611-7011 USA


h'




" i ''"


'IS


* A.
*1 2..
* I. I..


. ... : : ...' : .. ..,..: K .. .. l




Full Text
xml version 1.0 encoding UTF-8
REPORT xmlns http:www.fcla.edudlsmddaitss xmlns:xsi http:www.w3.org2001XMLSchema-instance xsi:schemaLocation http:www.fcla.edudlsmddaitssdaitssReport.xsd
INGEST IEID EQWRBYFFT_TT39DQ INGEST_TIME 2012-03-26T15:42:29Z PACKAGE AA00009473_00001
AGREEMENT_INFO ACCOUNT UF PROJECT UFDC
FILES