Supplomontto BUCKT.ING PIATru OT T1AT P1YWOOD IN COMPRTSSION, STITAR, OR COITtsTNTD COITPRTSSION AND SHTAR Information Revieu.redand Reafflrmed September 196l LOAN COPY No. l3l6-f Please return to: Wood Engineering Research .Forest products Laboratory Madison, Wisconsin 53705 EFFECTIVE I{IDTH OF THIN PLN.TOOD PLATES IN COMPRESSION I{ITH TIIE FACE GMIN AT OO AI'ID 9OO ro rcADI By C. B. NORRIS, Prlnctpal Englneer and A. l{. VOSS, Aseoclate Englneer Foreat Productg Laboratoryr2 Fo.""t U. S. Department of Agrlculture Servlce Surmarv Thle report presente the resulte of corrpreeelon teste of thin plywood plates at 0" and 90" to the face grain directlon to determlne ttie atrese dlstributlon under load and the conpresslve etrength after buckllng. Presented aleo are curvea for determlnlng from the propertles the rreffectLve of the naterlal, wldth ratlo'r of plyrood plates in conpress.lon when the edges are elnply supported ln a plane, the rreffectlve width ratlorr being defined ae the ratlo of the maxlnnrm load sustalned by a buckled plate to the maxinmm load it would carry had tt been regtralned from buckllng. Purpose Fornulas for the calculatlon buckllng atresses of plywood plates of crltical oubJected to coryreeeion, shear, and comblned compreselon and shear are presented ln Foregt Producta Laboratory Report No. 1316, rrBuckltng of Flet Plywood Plates ln Compreael.on, Shear, or Combl.nedConpreselon and Shear. rl The compregelon formula was checked experlmentaLly for stresses at 0o and 90" to the face graln and the data ere presented ln Forest Products Laboratory Report No. 1316-D, [Buckllng of Flat Plyvood Platee ln Conpresglon wlth Face Graln at 0" and 9Q" to Load. tt At stresoes below the critical buckllng streae, the uaual fornulal may be ueed to coryute the strese from the load on any te report ie one of a gerlee of progress reporta prepared by the Foreet Producte Laboratory to further the Natlonr I war effort. Results here reported are prellminary and nay be revised as addltlonal data become avallable. Orlglnal report dared Ocrober 1943. 2 --M alntained 3 --F at Madleon, I{ls., in cooperatlon wlth oreat Products Laboratory Report No. 1315. Report No. 1316-E the Univereity of Wleconeln. gLven plate, After buckltng occuro, theae\formulae .t" ,,oa appllcable becauge It was the purpose of the etreeses vary over the crose secttone of the plate. ln plywood platee aubJected thle study to deter:nl.ne the etress dletrlbutlon wldth ratlo curves for to coryreeslon and to determlne emplrlcat effectlve coryutlng the courpreeslve load that a plywood plate wlll carry after buckllng. The effecttve wldth ratlo le deflned ae the ratlo of the maxlmuurload the plate Bustalned ln teet to the maxlmum loed the plate would have wlthstood had tt from buckllng. been regtralned DescrlptLon of Materlal wldth ratlo curvea were the The epecimens uaed to deteruine the effective For a deecrlptlon buckllng fornula. aame BpecLmeng used to check the crltlcaL of the epeclnens, the matching, and condltlonlng of the rnaterlal, -arklng, buckllng teet method and the coordlnatlon of teets, see Foregt Product8 Laboratory Report No. 1315-D. Method of Test The evaluatl.on of the effectlve width ratto for thln flat plynood plates wae based on coryresslon teste of plates eupported in a spectal frane and on coryreselon tests of coupons cut fron the panela, using the so-called pack teet apparatue. The pllmood panel conpreselon tests were made on the game epeclmens used for the plywood buckLtng study and wlthout removlng the plate from the teat frame (Report Noo f316-D). The speclal frame for plate teotg Le shown tn flgures 83 and 84..:i The method of conducting the compresglon tests of plywood coupons ls llluetrated ln figure 81 of Report No. 1316:D. In the plate coryreeslon te6ta, the exact procedure varled somewhat ln relatlon to the buckllng teots on the snme plateer and depended on the ratlo of che streas. erltical buckllng stress to the proportlonaL linlt buckllng atreas less than 75 percent of For thln plywood havlng a crltical llmlt the proportlonal stress, the plate coryreesLon test was made lumedlately buckllng load. after the teet for critLcal After removal of the load ln the and buckllng test, the apeclmen waa agaln l.lned up with the edgee etralght parallel. Gompreeslon gages were attached 3/8 lnch from the edges of the apecinen on both facee and a gage was mounted wlth the splndl-e ln contact wlth Flguree 83 and 84 defl.ectlone. the center of the plate to meaaure lateral show the two facee of a speclmen ready for test. 4 The flgures and tableg ln thls supp'lement are numbered consecutlvely wlth those of Foreet Products Laboratory Report No. 1316 and supplementa A' B' C, and D. Report No. 1316-E -2- For thicker plywood, having a buckllng stress greater than 75 Percent of the proportlonal stress, each plate tras tesLed slrmrltaneously for plate comllnit The load was applled presslve strength and for crltical buckllng load. A11 gages were ln equaL lncrements untl1 fallure occurred. lntermlttently was approached, at \ilhlch tlme the fallure reed after each increment untll gages were rernoved. Another series of tests was made on nlne plates to before and after buckling occurred, uslng determLne the straln dlstrlbutlon the same loadlng condttlons as for the plate compresslon tests made to evatuate as the load were meaaured, effective wldth. Stralns in the same dlrectlon uslng 1-lnch metalectrLc etrain gages on both faces of the plates at Polntg 31 4-112, and 6 inches from the edgee on the transverse centerU2, l-U2r llne. A1so, 4-lnch coupression gages lrere mounted on gage llnes 3/8 inch fron the edgee and a dlal gage rilaa nounted wlth lts spindle ln contact with the center of the plate to measure lateral deflectlons. Data Presentation Strain Distrlbutlon Across Plate etudy on plyuood plates ln coryresTypl-cal data from the straln dletrlbutLon slon are presented ln table 12. Readlngs of the slx metalectrlc gages on the In colunns 9 to 14, the north facl of the plate are llsted ln coLumrs 3 to 8. ' The 4-lnch readlngs of the correspondlng gages on the south face are glven. gage length conpfesslon gage readlngs are tabulated in columns 15 to 18 and are deslgnated by the number of the nearest metalectrlc gage. The lateral at the center ls presented ln coluur 2. or buckllng deflectlon The rnetalectrlc gages read straln dlrectl"y, but the readings of the 4-lnch gage length cornpiesslon gages should be dlvided by four to convert to strain. These data are plotted ln flgure 85 wtth the compr6sslve etral.ns ag ordlnates The sketch above the curves axls. and the gage numbers al-ong the horlzontal Each shows the gage posltlons along the transverse center llne of the plate. plotted polnt was determined by averaglng the readlngs of the two netal"ectrlc straln gages mounted upon the same gage Line but upon opposite faces of the plate. The currre of average etralns acrose the wldth of the plate ls glven Numbers on the curves rePresent for each load at whlch the gages were read. pounds. loads ln hundreds of These data are replotted ln flgure 86 wlth the load as an ordlnate and the average compreesive straln of each group of four gages the same dlstance from elther edge as an abecLssa. Curves for gages 1/2 tnch from the edges are labeled (in-fS-On-6S); rhose L-Ll2 lnches from the edges (2N-2S-5N-5S); and those 3 lnches from the edges, (3N-3S-4N-4S). The curve for the 4-lnch gage length coupresalon gages at 3/8 inch from the edges is aLso sholtn ln this flgure. Flgure 87 ehows how the lateral wlth the Load. Report No. 1316-E deflectlon -3- at the center of the plate varied Effectlve Wldth Ratlos Effectlve width ratlos obtalned ln thls eerles of tests are preeented in table 13 together wlth teet data and cornputed loads. To determine the effectlve wldth ratlos at proportlonal lfunit, column 2 or 4, the data obtalned durlng the plate compreeelon test were plotted as a load-etraln curve as ahown ln flgure 88. The stralne used were those meagured at 3/8 lnch from the edges of the plates. Entering the curve at the straln et proportional llnlt determlned by che compresslon tests of the coupons (polnt A, flg.88), column 13 or 16, the load on the speclmen at thle strain was obtalned (polnt B, fig. 88) colunrn 5 or 8. The streee et proportlonal llmit determlned by test6 of coupone, coLumn L2 ot 15, was used to the load at proportional llurlt that the speclmen would have carried "orprrt" if buckllng had not occurred (polnt C, fig, 88). Thle load ls entered ln col.urnn10 or 1.1. The ratlo of the load on the plate at thle etrain (B) to the load at thls straln that the epeclmen would carry tf lt lrere restralned from buckl.{ng (C) ls the effectlve wldth ratlo at proportlonal ltmit and la entered ln colunn 2 or 4. .If the plate' fatled before the proportlonal llnlt straln lndicated by the coupon teets waa reached, the maximum load was used ln computatlng the effectlve wldth ratlo. The effective wldth ratlo at maximum atreao, columr 3 or 5, le the ratlo of the naxluttn averege compreselve streaa acroas the plate, column 7 ot 9, to the maxtuum streso that the plate would carry lf tt lras reatralned from buckllng, columr 14 or 17. The latter maxlmum stresa was couputed from Ehe testg on coupong. In columrs 18 and 19 are entered the equare roota of the ratios of the computed proportlonal 1funlt atresses to the couputed critical buckllng streaaes taken from columr 2 or 8 of table 11. of the report on buckllng tests of these Bame epecl.mene (Report No. 1315-D). The effectlve wldth ratloe at proportlonal lfuntt are plotted as ordlnatee ln flgure 89 wtth the aquare roota of the ratlos of computed proportlonal llnlt streases to couputed crltlcal buckllng stresses plotted as abeciseas. The effectlve wtdth ratLos at maxlmun load are plotted ln a similar manner ln flgure 90. . Analysle of Resulte The study of straln dietrlbutl.on acroes the wldrh of the pLatee lndlcated that the strain le uniformly dietrlbuted buckllng untll the computed crltical load la attalned. Figure 85 ehows that the compressive straln remained practlcally unlforn across the wldth of the pLate for loads up to 400 pounds. At 400 pounde one edge was stralned a greater amount than the center or the other edge. At 500 pounds the strain at the edgee lraa at leagt twice the etrain at the center. The buckling, or lateral, deflection of the center of the plate etarted at about 75 pounds and increaeed to 0.1 inch bt a load of 470 pounde with no lndlcatlon buckLtng load. The computed of a critical crltlcal buckllng load f,or thls speclmen wag 350 pounds. ThIs agreemeng Report No. 1316-E -4- buckLlng load and the toad at whlch the straln between the computed critical becones concentrated at the edgee and relleved at, the center of a platerwaa observed tn all nine specLmens studied. buckllng load, the eEraln became As the load was lncreased above the crltlcaL concentrated at the edges as ehown by flgures 85 and 86. The average comvanlshed aa fallure ltes aPProached. preestve etrain at the center practlcally Flgure 86 showe that, after buckllng occure, the average stralne comPuted from the readlngs of the 4-lnch gages mounted 3/g lnch from the edges of the plate gagee mounted 1/2 lnch are greater than the stralna measured by therl-lnch Much of the from the edgea of the plate on the same transveree centerllne. to the rapid Lncrease ln straln as the edge of dlfference can be attrlbuted the plate ie approached. Extrapolatlon on flgure 85 to the 3/8-inch gagellne accounts for 40 to 60 percent df the dlf,ference. ite vertlcal edges pull ln more at the center than at Ae the plate deflecte, the top and bottom and therefore the A-lnch gages measured the change ln The l-lnch gages were of length of the chord rather than that of the arc. the metalectrLc type and therefore meaeured the change In length of the arc. Computatlons show that tt accounts however, ie negllglble. The dtfference, for only 5-Ll2 percent of the difference between the two gageg. direction ln a veftlcal It ls evident, therefore, that the atraln dletrlbution near the edge of the plate ls not unlform but ls ma>rimumat the top and botton cornerg of the plate and mlnlmtrm at the center. Durlng the tests, it was noted that the greatest curvature occurred near the cornera of the piates. The deflected surface in thdse areas approximated a portlon of a cone wlth the apex at the corner. Thls same concentratton of In the bendlng wag observed ln teots of Longer plates not reported here. longer platee, slmilar conellke deflections were noted in the corners formed by nodee and the gulded edges of the platee. The platee generally fall.ed neer the cornera where the compresslve and bendlng gtresaes were concentrated. Slnce thie occurred outside of the range of the 4-lnch gage length, the meaeured strains were lesa than the maxlmum stralne that ln the pf"t". 6ccaetonally fallures occurred before these gages lndiiated llnit the proportlonal etraLn, calculated from the compreesion tests of the was observed ln 8 percent coupons, had been reached. Thls premature failure to the face graln, and of the tests ln whlch the load was applled parallel to tn 30 percent of the tests ln whlch the load was applied perpendicular straln lta8 llnlt the fate graln. When the specimen fail.ed before the elastlc llmlt etrain obaerved, the maximum load was used as the load at the elasttc wldth ratio at the ProPortional- Llmit' ln the computation of the effective The stralns measured by the 4-inch gages were, then, less than the maximum buckLing stresses were stralns ln the plywood plates when the critical 88) exceeded. The observed load at the elastlc Limit strain (poi'nt'B of ftg' strain' llmlt ls, therefore, greater than the toad at the true proportional Report No. 1315-E It follor{s that the method of computing effective width ratios proportlonal llrntt glves values whlch are too great. at the The effectlve width ratlo at maximum stress was obtaLned as previously explalned on page 3. This ratio was based on accuraLe measuremenLsof Load and area wlthout lntroducing the strain readings. The effectlve width ratlo curve ls glven in flgure 9. The effectlve wldth ratios were plotted as ordinates in figure 89 and 90 with the square roots of the ratlos of proportlonal limlt stresses to crltical computed buckllng stresses as abscissas. The abscissas are, therefore, ratlos except for of the wldths of the plates to the widths of plates, identical wldth, which would buckle at the proportlonal- limit stress. These abscl.ssas were chosen because it seemed logical that they would lead to an effective wtdth ratlo curve which would apply equalLy well to plywood plates of alL constructlons. There are probably, other factors which influence the value of the effective width ratlo. The existence of such factors ls indicated bj the dlvergence of the points for t,ests with compresslon parallel to face graln from the polnts for tests with compresslon perpendicular to face grain as the abeclssas increased. The effective width ratios may not be exact due to varlatlons between the minor test specimen and the buckling test specimen. Also, the buckllng test specLmenswere of such proportions as would glve a minlmum crltical buckllng load. However, the curves are belleved dependable for the range covered; and the effective wldth ratio may be determined for plates from the properties of the materlal and the plate dimensions. Conclus-tons The straln dlstribution ln a plywood plate simply supported at the four edges and subJected to compresslon parallel to the face grain or to compression perpendicular to the face grain remains relatively'unchanged until the computed critical buckllng load is exceeded. After buckling occurs the strain dlstrlbutton changes rapldly with strains becoming concentrated at the edges of the plate The comton compresslon formulas.are appllcable for computlng loads, stresses, or stralns before buckling occurs. After buckling occurs, a portion of the plate may be consLdered to carry the load. Ihe width of this portlon (effectlve width) at maximum load can be determLned, if the stresses are at 0" or 90" to the face grain, bY the use of figure 90 in connectlon wlth the plate elastlc and strength properties and the dimensions of the particular consldered. From the nature of the evaluation, it ls evldent that the effective width ratlos for maximum loads are lnherently more accurate than for the proPortlonal. llrnlt loads, which are indicated as being somewhat htgh. Further study Ls necessary to establish more accurateLy the effective wi-dth ratios at the proportional limit, and to determine the ratLos at other loads between the crltical buckllng loads and the maximum loads. Report No. 1316-E are lnvolved becauee of the compllcated etreae dletrlbusuch determlnatlons buckllng load has been exceeded. Further tlon ln the plate after the crltlcal behavlor Btudy r'ould involve also the mathematlcal analyslg of the elastlc comPllcated mctte of the plate lrr thle range and the {evelopment of new and teetl.ng technlques. Report No. 1316-E -7- ,7 -24 ttr rrroroo t eC €aal EI !l pt it t^t I to|l rq' ,rloldt . rel i Ila-i--,|' | 6t | a I r Coq0r OA! r^l | otEtFr k !,{rt{ail Oa, lel a aolar | | d{te a {---Q0 da I r .{t0r | | r. .-r Eq Oct.cl at I lO. d.ottord. acl 6 | rel a rll | | OC a | F.dtt a a I Arrr€)Oal I tAr E O ll tro | C) ar{t+{a I av a tta a t Aa | Ea Ot Er ir I .{t o I Oa : :^! | lvl <t | ------.a | | | ctr | ra, rtl Er rlolOa € | | lvt a | a ! | a ----Ur a a !r I a < t aI r^t € | .a rF a a a tvl Oa | ! tit a --t-\a | | t | lr !0 r a a I a^. qlrO.rtalOl Q0r al.' ret Ita a | C, | | -i--t < r! | t kr+ta | .tt I lr I ll t^ IIort',rroI O I El | .tv Aa | | C a a ----.lta | | | | -Q, '^r r rF I rg{tt, I | ava | attl la alrl rrrlooo a aEl r^r adtto, I | | avl tttl ----r 6; A o d t E{j O Ct . O lo . Ct oooooo O rt o O O F . O I I | oANtot(, - aaa.a 6atF(Dct 6i'0|'Jt ro6lSlir{ r{'{6|loato - O . O ta a O rO . O - - - o at o oo.|c'rto C, r{ Ol tt r - C, . o rO . o O r A o|oooo6 ooooo o6liroo OnOeolO aaaa !tItFOO aaaa ddA6lro!o d It-- aa-t a.aaoa a' oooctro rO F !tFd!tF A.A Ol FI O o o o o o oo o r a oorloro aat (t{rFoC\l .'.dOOOcl| F o O ol roa r. o. rooa o . ! & O F6|'IOC'C'A c' A O6|!t.'FFo ararrrt - - - o. or c. ' i{ ' ..x a a . -- ----: oocrctct o.tcroo.'o .aaaat c1 OOOA6|a aaaa t - - - -?, rtltFCrN Ad -, - - ct 6 ct o.'000.le O O A r.tolrorooo o o rt Cl16r|Ct|)O Ct C, d Ct c, . o ct . A ctl . ol t o o o. t r ' t o . ' a F |.,;s :i! o ---- ---- Fro€rcrcrct aa tro@ooo. a)or)ort . tt - - O O Ct g .1 lO I ottooo N?Or{rt AAA6ICq oortr)n .o |o E e aa aaaal F O A A aa 6l!tI)FO .1 AAAA -ooooo aa o o oaooF|fr a. OAOOF A,{ | t- -i-- l | | I a | r ooooo .ooooo -- I dA ttalt - I I I (\| o(|oato aa @oooo Aclt€TFae rtaaaru --.---E oeooo.gl a | 6l ------ Il : I aa ol -- t-t- ct (, a -a-.- c) .,O aa aaaaaa ------ O . A A ---t- 0Fooo - | | | ctrDooo ctoli'F'.i, ctro3)orost tOOrO€|o!t o .{ -9 o'.i'6.'l(,A aaaaoa O.1,{o|aO{ 6 F - i ' - - ooooI)o ct O . O | - O !t - I a.l i o a a FOOOA Ct c) . ao aaoa ---a t t I €too.)o cto{oF (oOI-rr/raF - aao tct a r.|la.{r | | a----I a | | tO t^r r/alOa a tva I a tO . O - ----- atal r^r I a I a(a t!t rlO Id I r a avl aaar a t o---tttl l^r | , I rE rlq, rltr.ta r I I tvl Fa a I O | | ----it , | ar r^r a o I aGo I Gl o r a,a rrt k a a, I rva C I a Ar lrkt----Ot | | o r.O I raa a..,aaOr,{r Irt.r.llrdt O a O a rer tl rlO a a ra a I r---- h! I C) . O | ' C, .| F ct .t cl O O F O A A - - to(|ooo|' at tr0.oo'dA ooI'l6rt ..1 oaa 3\lNtloO Al4.aA A oooct<, FFFro.o o.loooo aa toJ('FFF -ooooo .toocroal o 11 A aaaaa FOOO.{ A6I..!ratltO a - - - raA - l - torodc,rttorte|oartQ -Fatt-oc!Ooltrorae{, FFA'6ibOFFFFO(DO .aaa Fl .al € a o ri N o I ratl | t€l r^r !l r.aatl .e. Ol ral I C, O o ;l Ct o Ol oo cro ') lal ggFggEE9Fg; .aiAAA N F + E N dd 563883 o d d a a oooo 600 oa660q 664 ,ts 6 d N A a O d 6 a a o o o a o60 NANd o a f t d REE EggFF3F3F €FT:EgE:ggEfigg'F ;oa N;; aNd Noa aao odR ddd odo d d . o35t: 3;$$9cce rt3ttt8t3 aao ooa N OO {dD N ?6 d{F .@6 .ia tA O ro- NaN o90 6O€ dNQ ' oO ' oo . i d i N i i d d d N d ' d d g$36g$€gBFF$ EEBii: ggfi*EEHEH gEeFfrEgERE8ggts :83 s3gg:€ fiEg:F8 gEFEi9 ;1 {6 . -. nan 6ad +r. 60. o.€ noo ono 6oo tll 6{0 { '{ E 6HRRRs$38f;8 33383t83838t ooo oao oF6 006 NFo 9tsO 000 i oo 160 006 Fod aFr 000 oFo aaa 000 oao no6 ddd Naa oNo oao on6 NaN 3 :::3REEEg 6.-aDooo ANND :o 'R $Fg83g3E -'-'.:;;'ia'o'6 o,ncoeaA E:::rSdSFB :RfigF::3Fg a d N d EE$sg18f;gl N N I A@DO oa 60t€ ooao o6oo oaot 6-AOOa o{6D aoNo 60 o' o+oooFd looo 6aI doo oNod dd.6 oo{o F{ 3BB;;g;ggFAgggss 6I o D r rt = N ri o o o o 33t338 a D a d d a 6aaaoa l 6 N O 8C ;.i aoo 43;3Sts aoo N A HI s:sBEi;sEE:EtsEFl: qElls-EE-ie isg:EERRE 1'lsgteE;sf;EEF:E:eEEs lld . 1 . 66a ano a;,t G[aGi i'[i dot6t a"tci Nao 6iold oiNN Noo 6ot aoa oNE oF6 eiq H $.Et iiF.eii qieiiq e3.E tai :.ii ttt qqi$.{tEt8. is.?iqqP.ig. ifgl j-'.i i:j ij-- jcici ;i; cieo Nio ;d ;;; rs' iaa dao -.:- --- essE:Egseaia:-qA $FE s:BsRB ;$ssiasrs Ege f4leeaF!: s;BB$E e:EEeE ;;:;: 3;; ;;:3 ;:;:; ;r;' ;"rd ;';'; ;;o' .'.'; o'do' dni6 dr'd -'.io' o'n'd ;:;.: i::i ;;; ilsl ;;;1 E d!l !l ooa ooa ooo dao d60 60a ooo 90d dQN o60 ooo ooa aOF Ddta ooo o9€ OOa oar ooo d{o FdO oro od oo a g qtsO aii Eei E.3.F. 3REFgEqqtqias.EH. 9oa ryFl EoF NNo 6.A { II ooo ea aoo oao{ol oooooo 60{oaa oNOO raoooo I 8 9 oo ooc 8 3r3 a o 6 ;,; e 3883 6dooo JJ fl5 c3R133 tsobo o€No tl ;; 'l-1 NNd ada 8 3 S e 3 3o o o i oooooo aooD €@NO o600ao J Qqa OaO ! ! d ooo d o 3 ; - d I 3 6 .: 3 .r .t .r,r,i oaoooo AF 3 - I 5 Ia g .' .' 6 9 I R H d' d d Foao fro 3 i O O O O O oo 89;$Bd gcee;d odo{ 6 S d 9 . 3\ d o d d N d N N ad F O O .i 3:83fi9 ooo aao oooo tO oonca@oo sSSgBaRX o@o6 e5EC39P d 6 6 6 O . gg3$Ha€fi$!Eiaess$E h tQ o o ts ;,i-;-. .{ qa r- -3A Ai 2 : 6 6 i :5 N tFFd383 doooo oooo oo CBRSXR oFooo eqqqeq AA A NNN- F a o - o d q a o N d O O O d A A d N N :88 E3gEE:E:9BRiR:FF8g:98 FiF T;8 R3g3E:gE:;iE rtrt; dji aji {na ttdN arr soti ada s9s3 a ooo ait aNo 6€0 166 ooo a-o io6 n6S ooo 66r oFd 6lA E Od ooo oad i{n 066 Ndo 6aa aa6 d i l a N a a 8838883 3R9 EgE E:8 8gS S93 993 938 e&3 E9: RR88R9 93S 600 ooo aao N N O O ddoN oooo oo o d.N aFO A Oi ooo 600 oo9 do9 ttl l?a ooi 6.O @OO dFO OoF a . a a e a a a i i d i d i d N d N E o8d 3o t @9 o8o 9 3 S oRN g s6 r 3& 3 3 89 3 3 3 o8o go e 8 i6. d 6FO 6-a noo 000 060 air @ 98 $.t{p.EEs-leH.i6ses. ro oa ao *ljo'd'o'o' {iqAqg.t{:.E..Aiqi io € E oo060 HOOoO 9P8 G t s O O aao F t s F A e t o o ooaooo o9FO€N ooo000 6{F06 I E 33RR3 ooG{ N6loo ai3aae83.e3.iaaiaq a NdaiaaaaNdNd&a oooo60000 @d-oF0 @q roDoo ra6006 oaoo oiai @a oo@ d o N o ooao60 oFoo .aNNaoll 6000 o66d oaoa N+ @FOaOA aooo F O F O @ O :g*sF;BFgs F q F € O F aooo 6 D 6 0 0 t i o @ @ {o aaa @ Fc {o ro F il E N 00000N {o@o€o edQsoetsoo OdNff ooo no onAd g:g ge8eEg938sgssF8:38FFF fii; gBR 8Bg3;sgBF :ggBgF ooo 06€ noo ooo Naa aaa Naa NNR aNa NNa ooo ooo non .oo .dd ooo o@o ooo odo .O6 AAN NNN OF o l N i N F 6 i F o ER$3frR9RRRRRR;E 333338838883338 ooo ooo ...j iJJ 994 OOO OOO OOn ooo oF@ ooo oN d 006 { r N 6do OOO l € 6 N oa Ni A 60O NON NNN 900 oao oFo 000 16o oan 000 oao ooa o6a 000 No6 NoN 600 o90 09@ 000 a@6 oon +r{ OOO 6 F 6 6F6 006 i;FtsF 0O6 6 0 A 6Fo 0O6 N r € o60 006 O F 6 aaa OOO 0 0 6 066 006 d N O 060 OOO o N C oNa 0O6 { n O doN OOn € O O aoo ' OO .oo .-r OOO {oF 6+J OOO ooN rOO A dA A NN NA N .NA iai iii 000 6-i as6 000 ftd6 04. 000 60@ 0o6 000 aFa 000 o€0 000 tsol 0-o too 000 ooa ooF l+l 000 kra Noo 616 000 o{o 66F lar 000 ooN oo€ rll 000 od@ 000 ooa ooo 6o0 fr66 NNa 006 oo$ ooo oNo 600 ooo ooo noN gNo ooo @ao 9oo ooo ooo ooo ooo €@F NNo ooD oo@ oon ooo ala dFo ano oo9 doo NaN NNN aNa ooaooooFAoNdo+ NSSRSRRRRRS&REEAfi3 oo9oooooooooooo9 oooooo6o6ooooooo r{l €t{ odr. . &a t60! AtSd o.oO Ad. | dq. d 6 o . ora. ooo r@i ooo lod nNN Nao ooo ooF ooo oon ooo odo ooo o@o Nao asa ooo o€a 6aa oa{ 600 o60 66F NNd i oo€o qoQo $85e o i @ o o o n do iv o a o € F 5:tr-------r- aiol loq o Ao eq r . r AAo. a. E or 6 | o ca t ao! r di dka L E d Ad | ro rv N O O N oo €€ d N i o d o a F N O O O 6 € o @ o o F @ N A @ F N O O l"rr ! . 1J ,{l oo ;338393339RR99 o F @ o o o 6 d d @ o o oooo ooo€ ao ooo on ooo oooo 6@ nn :i---l-----:9 l li c E E I 0 r i. t€ o3 r X , 6 E r i oooo oooo oood I I ooooo oooo @i 5ggfl da d | 0 { o I o r a r a r i A l I t o o I I d d r . l g < . r i ! a o ! r . | | d o o a r O | | i RN$39:EEF$HBgFE€;g J A $ d . i g" . I E. <tse E I I d i ahl'-"':' hr I i . ro I rd !. Aid Arr 4 I t- I | q . H. I . I A | | <o A | I | | I Eo 4Xt 6. g. E @ 6 0 0 6000 a N 6 - . @ a a oad@ r r^ .v I ;8338 { o o r+ o€ o @ oo d* r dr--ir--our i i ror aig ra :5- i ari A I .: E I Ag av 6A {ooo€6 ,"2 i € € B R3SR36:BEBE dddira € * fi; * 14 o o :: fi fi fr fi f; i i @ F i !r N r q 0 6 0 6 0 o F o F o o i @ o 6 o o I 6 O - N N S 6 4 F O A A O @ O 6 O d O A 6 d - O d o a e a i l Y , t r e I € a o { r o F O o o . I d o o o 6 o o o o d d o d is i :i . o r . : !: I t a l l ... E90 aoD ooo @ OO o- o ooo 0O6 odo ooo oer FFF ooo -tsO 6ao ooo ooo €oo ooa ooo 60d odo ooo 60N oF{ 09€ a00 00c 016 666 066 606 666 ooo A iO i6a ooo OrO Fdo ooo llo dtsa ooo 90i ood ooo FdO aaa ooo A dO aao ooo Olr o09 ooo FOt 004 eoo A O a t a 6 DaF OOO 4 A A I - r - - r a l r E i r a l t . r a o a 5.1 l + a r d l . . t r . . i o r i i .^.H .Fr t . r a l i . I q a k I r a o r r l r q t I r a , r t . | < a o C r d g O r t t . o . l a a . o i a I . r A U O r O a r t > r r . r o a r A r o r k r t r ^ . q :. Y:rI l df r I O F o o o o o 5 rrl E O O o o d 6 R E r r'Hq .^.qg r6.Fl r-.319 OOO OOo @Ho oro OOo OA4 do6 ooo oOO EOa o06 Noo Ooo 60o 6ao o{o :^i4.1 333 RPR 93: Roo r d {oa R 3 d 6 3 o h F 6 6 o 0 o 0 O o o 0 o 0 o 0 OOO {aO aoa R 0 ooD -6. oo@ o.o 60O a6F oNr l.r ooo daa o-o Don OOO ONO ooo n.o OOO ooa oo{ ono OOO 006 ooo ooo ooo ooo ooo ooo ooo R I R o R oOO itso ooo OOO Fo@ aao d F 6 O r o 0 0 9 0 I 0 9 0 R 0 S e 3 ; E OOO OOO 0{6 dad OOQ ilN DoF NoN O9O l5O OO9 nFo ooo ooo NoN aNN Ndi ooo ooo ooo ooo ooo A l t i "':-'-'" i .oi ! . " i . lE : a q t X { d . r I | h { a L I o . ,.,F '{ { | 3 i . E r l - l - I- -o l I d A r 9 t o o t . r d . | | r d | | I a . a t I o d b U i d C l h . > a | < ! : E E r i I r. ' o- r i I I I od . kE o . o ra >.k ra arA !aar aior .ta laol ai iAtq c oi o E ls, i a o I alAr ool t b! aAa a I o rk r, ro o d a h c I . I a I o ad k d & o! :-tslsl | N. o o .{ 5I i3i,:I" q o | | a alld 6!! o o o q q E R ooo ooo 359 3:3 98; ooo $dS 849 333 R:3 :S3 BE8 dla q i iEIfldI 839 393 153 S8ts I;3 ..3 S ts o ' 6 q a o q q 5 q R o R q N F q F $ o d q q & q R o O o o d t E E q E E q q q q r *l 8 3 3 3 3 : t 8 3 3 3 3 3 e 3 8 8 3 g e 8 3 3 3 e 3 3 8 8 3 3 3 e 9 8 3 R 8 P 8 8 C 9 3 3 9 9 3 3 8 P 8 8 9 :. da. : t"{E roo ooo Fo@ O€O oOQ oNa iiOOO aai Oot OoF @FF aON aaa aAa O@F iFF { a@d Nad aNd aNN ai.o<{oao6oooe89!! :;:d ri.il ria : E ialooaoo@oiolQq9 r^r { .o rd o d .d,J ooo g ooo 3 : oao Nad 6ao B saN NNN NaN adi dad dd- 3 3 ! i 3 3 : R 3 : 3 F a O O O O F F O o o o o a e g F i F F 3 E fi R R j B ; E :j g g g .i .' .' E B fi R s a i I s a E a I : € a o 6 d56o.r d 0 a 6 o a i i F 3 d I E r d c g g .i ; 3 : a o A+ 3it I i i r" i . r I r lo Xd I i=i r lsl I ur iai4:l I : {d : ; a - :fl5 E R ; rg[ir-'--' . r ! 0 ! . n k d , - r A q r . C r l A d a a o I O ! - a :ia i 8i i d . o a g o r , i I I 3:.!5t r Ar< ! . I I I r o. ir P. a. ur A. i . | c , . | I I t ! l i r I E3 F F p F r i.iq4 F -i -' X t rc a r. + 1 . < r h 6i: ----!o. aa I Agr I . o t t | . . oaa roi ATE -Aa <o A Ol | . . I E. lo < Xa aa i .----- I | I 3i':i Hr I | . | ak I | | | 2t "i i r .a koi ait {tr <o A .' i-iiljl iai 6 6 g g 3 e i q g fi g EB : E B J H o' 3 ; ; g 3 E 3 i s Es ar{o€oo. $9ss A F j q g j i Es6 o a . g r d -' o l r i i A e i r d o € c i-ldl ' r . E ot ta Ji lr-i4:t ro,dl I € :e:d ro" ; i I iai ; E $e iai s g e g $ A i ; fr 3 g g 3 ;E Ra EB F g g 3 s gE s 5E il ,t q E E E E E e8 iai $ ioi t q e q E q eqqq Fl @ o n {ts fi fi * $ $ *€ f; € €€ € 6€ g IE E .{ R3;353?sa*R9RFq8RB " N N I 39358353E oo AN i .:-- -- s.aq s.ae aqiaacqi!.qii iei EaE eaiqqa iaeqq? aaa eqiqgq iffl aqaqqsqqq !xr lil;{ ji.'.i"t;;6d;s'li.'.'"i.i'io's6o i"'.'ii.'.;*'.' {r{ ood .r. jj' r<j: dtito 'no ooo :s33s; oo gggsgE RftB*TERdRRE 33833833383 gFEgRi9R;EBIiE[ 33[3;8s3B€sHREE eB; E:fi eEa 8tBaE-a *'"i'i *'*'"i alata' ;.t; *'.ioi ;'.i.i .,i"i"i ;';'J -;; ;"'.t "i.,i.'i ":;',,i "i"i'"' "i.'"' "i;'i gEiili iii aiaqq8 Eqa esss8eEas Fss8BR BE:Ess ;ss;ssERE ela bl'il ooo o"t; "iN'6i.i6i.ii'n'"i oi.i.i "i'i"i jjj jri.i cicio'ii.io' .io'.i .ii.;:i 'ii6 .lc;i +'jj ooo oto fififrftHiRRMgEiEFFE$ HiiBssb'3s83qqqqqqq *rq 8E 3 e 8c 338 33R R 9 3 d3d8o :3n 63 e 3 e 33 8 E@E o8o9{ -3 3 ' oE o : F@ -d-i ooo ;;;;ll;6:'0 fid; j-a ;;;;;; ccc ooo NiN 1r$iF;sFHt$ dolo acoa 6a e:HFgEisqai o6 ;';;.isij.;.';6'"i q q E a E s. F s. e F. s. g. i E i" iEi i"isl * s E F .i .' r" .i [i i-rilJ I i rrllr :' i iq' t t rllal --- it io! O2o i -tr - - - - : - t - - " . i. i -i i . i iiitsaFFi i r i o --dcP;-; 6io--; { :if*ai Eig;isld o . A I gi A : :. a .r e a 6 :' a ; :? ;' E :' a E ;1 i o :' E o ; E i : *i -i € H 'i g E j i ; o I ; g ; B ; g o' :i 6 q i s 3 3 r { 1 6 l I r i I d o o . i-b:'-; g r l a e i r d E r . d E E a i s: B ieilrl si s- ' s. r e q R F "l EE .r i li r-i;lJ "i "i "i i li::6i tirsli o r a e i ;i4.,i e i 3 *3 i; e E: i e i a 1 3 e F H e8 . E i ! E i i d. a 1 d. .. "" r . i i I i : !: i ; i I a I d . E i i lii*lligi ; I ! r ; d i I o b l : 5tsi ,i ii l*i i.E;i.i r; e: ; | <o rA i | '' iei . 13 i : e i . oCr 9r d. E|O R 6 s q ? q q q ; * i i r-i i!l bi i :bi-----:-:-l3i ,i i iiiiii;i.i i r-i i -i: r I < o q q { s ii ,l =i!i"i Pr - E $ $ $ ! E q q i I i E q q q q q i q q A q 6 F E s E E E i I q q i E q q --i t H E 6 E E $ e' i; .i d I. : E q q q q a q a i Fq F o F il oi i:i :.Ei-ioboa i i : 6 d & 6 fi fi ; E F N o F drd fc od c) tr0 oo U g uU ) CEI do Era ;.! oo fo ok 'dA E do da) €o . Ql! qE Fr{ +D E O OF{ + g{ Elo ooo^ o E! opo t oO RE*, O QOA o E+ d,{ oto +oE al !v |A{h' 60 t Of od o *tE a k+ ,o +t4 0 6PFl hdt{ dd o Frd f I t.\ E o b e0 h E do 'o d 9t{ F d! 9€ ot oo qdo 3 D s& d6 Elq0 gc ,{o od +o oo <ro t{ CA dE o rto o DE cE oU oc <t fto oo o al{ oo h Ft.rt EO o! er+ o OE .t q0 d.{ Hq Ad t lia 0rt t{r E- tr! €o dd L+ 8.9 A f I J b I l0 h g R NUMBEPSON CURVES COaPE,PONO TOPLATELOADS OFPOUNDS IN HUNDqEDS $ saoo/d F \'| \'l \! N e- 6AGE NUMBERS ttggc z r'flars r 6j.-Jtatc ooulncmloa tcrt rhorbg ru.lt rtrelar llnc ol pletr ltr-l'.. ootcr traanverrc at polatl oa thc I $ eoo = q \ s u 600 0.@20 o.ooto dootS IN INCHESPEPINCH COMPaESSION tlgurc Z u + t s z oy 0.0025 85,--Plate conpresrLou test shorlug aversgo unlt atralo cr:rves fron gages on Plat€ 19r-4. I s R = 600 q N noo o.to o.20 0.30 LATERALDEFLECTION IN INCHES llgure Zu +zae:-t 57.--Buckllne ilaflectlon curve for plate 1!r-4. s $ d 9{ o d t {'JJ ro $ $ ofr gE Ul r{ F' dF{ t(l OF EO $ s Oi{ {J <t{ ql ot t r | JO Flk F| sl O{, Ed r{ OE O{t A.d UYI t t oo }{F rl oa, >o t{o EH o c rs Ld +r Fl 't e I(t OP q0p iEo E I I a u) u) H d o ,{ d tuJ q| Fl fq N N s) F o o \o (\ goNnod Nt 0t07 E N S ,n N LE6END I COMPPE'SION PARAILEL 70 FACE6RAIN o COMPRESSTON PEPPENDTCULAPTOFICE 6PA1N \ \ fr, ,., x vl 1- \ Ir \ !a4 T N a s o.2 \* \ $ S \.o PPOPORTIOIIAL LITWTS|PESS OF MITEPIAL /COMPUTEO CRITICAL 'rcKUNo llgure z M 4752A F 8t.--Iffecttve vlitth ratlo curvs of proportlonal SnPESS llnlt stress. I\| a; o o R rn k {t o EI t v s$ { E H E r{ a {t ql o ts T C) o {, d d h d {, E, d t o 'r{ {t o o T{ }{ 'T I a o o o t{ c q|t .Fl h fq { N 9\J\tsl dsSa'O Tvtrttvht to ssfalg'x/w/otMlggo 9g1a$ xrw t,r'a?Av otJld HJotntfAu2?ttt si F {l E N i X h ^ h t{ o (Dc CJO (d.rl oEl qo A O tr] Ptua (D Orl +rq{€