AN ANALYSIS OF THE PROPOSEE PEDESTRIAN AND UTILITY BRIDGE ACROSS THE RED CEDAR RIVER Thesis for the Degree of B. S. MICHIGAN STATE. COLLEGE Lester R. Shelden I947 THESIS ? rrIrrrrrrrgrjgrrrrrrr PLACE IN RETURN BOX to remove this Checkout from your record. TO AVOID FINES return on or before date due. MAY BE RECALLED with earlier due date If requested. DATE DUE DATE DUE DATE DUE Ira We) 6/07 p:.'ClRC/DaleDue.indd-p.1 An AneLfels or tLe lToposea Pedestrian emu Utilit; triage geross the hen Ceear River A Thesis Submitted to The faculty of QiCannE STAE; QULLLQL 0F AGRICULTCfie th APPLIED LCLWLUE BY Lester u. gueluen 'W Candidate for tue Degree of Bachelor of Science June 1347 THESIS &./ (5‘1";- ‘r‘ic. 0*);‘1 lJ—U * lb.) Introduction Investigation of Loeas Live Load Deed Load Determination of Stresses Floor System Floor beam Floor Beam Connections Main Girder Heb Main Girder Flange Jain Girosr Spiice Stiffeners lateral Braeing End Bearings Summary of Stresses Conclusion hxgerpts from "Stunourd specifications for Bibliography {1 *1? "V"! 1.2 *‘ } .L- k.’ {/5 J 1-} E- hibnw;y Briuges” An Analysis 01 tn; Broposeo Peoeetri n gnu utilit; bridge Across tue med ueoer Liver IrrsoIUeiios This brioge is actually unoer consiucretion by Jicnioun State Coirege, to be built across he Rec erur River beninu tne Grouno builuinp. Ene purkose of tne bricge is primarily to curry stesm pipes ano electric cables across the river from tee new steer generition blunt to the mein pgrt of tnc canpus. A secondary purpose is to act as a footbrioge. It is to be psrticulurly useiul to tn se stuoents going to and fr m tne tensors y steel classrooms. The original plans Were to builu a susyenSion brioge for tie utilities on‘r. Rhen it was ceeiceu to also use tie structure as a footbrioge, tne plate giroer bricge was assigneo. Althougn everyone concerneo fovoreo tn; plate girder bridge, the State Bouro of periculture seeiueo a less expensive LL) ‘_‘\ [0‘3 ‘s \ one should be built. Thus tne present piuns C&l; for a half—tnroubu(truss\ costing $12,090 to ylb,0UU comperco to an estimateo weO,Umu for tne plste girder bridge. Time oio nos permit the author to wait for the rinsl oeCipion as to uniCL type of uesign use to be useu. unercfore, tnis anniJsis is of Lné Elite gird- er type wrisn was i‘uvoreo. so much. The present incicet‘ions ere t1 {it this. t,,pe will not be used, much to tre cLegrin of thu author, wro nso nopeo to see tne realization of the plens he bio woried on. The autnor acmnowltog‘s his inc btoun.ss to all tio.e wno ncipee nim in the analysis. Jr. A . LOWLli, the engineer, who originally uesigneo the bridge, was very coogeretive, as were eli tnose in the Uixll Engineerinb beoartmtnt. Professors C. L. nlicn enu L. n . noberts were perticuinriy meio— ful. Tnanxs shoulu also be given to tne flichigen Ltste Lignwsy Desertmcnt Ior tne loan of a set or Sp cificetions. June, 1947 Le ter h. oneloen InveStigetion of Loeus, Live Lose Tue amount oi the live louu proveu to be quLC e uroblcm. Ire piers cilieu for eunerenee to th fourth eoition of "Stunouro ipeciiicstions ior highway Erioges" as a oopteu by the A mericen A‘sociution of state highway Officials. These speCificetions cell ior e live louu or be pounus yer squere foot on the sioewslfi While QCSighlPé tie iloorinb eno ricer been. When oesignin; tns giruers nnu OLMET manoeis, txc live lose snoulu be oeter- mined by the formula: quU . ob—u P-: (00 i —’1; ) ’30’ ) This gives a live logo or only be pOsnos per souire iOot ior uesisninb LLQ (- w ' Ur Main birucrs. hosever, these loeuinrs were not sgecilicell; for tootbricgc , '71 Which seem to be a bprial cs e. ne tniro euition of trc same syecilicutions cell for slightly higner loadings in escn case —— loo bounce per SHULTS iOot for floorin; unu its imueoiete supports enu e formula similar to the above for the girders. But tne third eoition also stipulmteu test all p rts o; iOut- uriuges should be USSLSBcU for a live loiuins of lOe younus per sauere Loot; no recuCtion DGinb mice for tn; main blfU:TS. in the absence or a speciiic Statement concerning IOthrlQEGS in tne iourtn eoition, the autnor was forced to use his oun uiscrction. Feeling that curind some college aetiVities, tne live loaning on this brioge woulo be more tnat the ususl iootbriogo losoing, 'ne tniro eoition's loaning oi lOO pounus per seusre foot ems ueciueo upon. A large amount oi tnougnt Wes also spent in consiu ration or impact on footbridges. sbec. 5 Cells for no impact witn sidewsli loses but this easin was ior highway anu railway brioges With sisewelis. “me posribiliti s of naving extreme loans on thiS footbriuge et sueh times es tLe Enter Ce ruivsl, Freshmen - sepiomore tug-o-wer, or when lootbsll genes let out, were consioar— ed. It wee oscioeu that wLile some insect woulo very llKEly be oresent, the luD pounds per square foot Wes generous enou h to allow for any locding .sicn might exist, plus an allowance of 50 to 105 per Cent for impact. ibis allow— rence for impdct offsets a possible reduction in loading cue to tne lerge widtn. It Wis not thought possible tnet ell 9 feet of tie Sideweln would ever be loud— ed to a pdcied conoition, which would be neCesssry to prooucc loo pounds per square foot on the sidewalk, and still have tne lOuQ mQVing so tint impuct should be considered. TLus the live loud, witn possible impuct inconeo, Wis set at 100 pounds per seusre foot. lOr tne 9 root w lingy, LllS Elves 900 pounds per lineal foot of bridge. Tne possibility of a v bicle creeping tne bridge presented itself, since (.1 tne walkway has suflicient cledrdnce. finen eXamintd with tnis in nird, 3 shown below, it was discovered that in h—l: highway lo ding souls produce less bending moment and sneer on the mein girder tnsn the Specified sioeneln loading of 100 pounds per seuure loot. Cimilnrly, a single truce or greater weight could cross sifely. SioewelK—loading of 900 ¢/ft. V - p wl = 3 Susi l04 = 4‘,soo g 3 - 1/8 mix = i/s etc h (lot); , 1,;1a’s,u fL. is. Libhwuy lceding g—lb (abO f/it plus e concentrated lose of 19,30b; for enedr and lo,SUU? for moment.) tuh— ‘ V = wl x P = s eso h lOe x ‘9,uUD = dd,4bOJ M = i/B Wl K x f Pi = 1/8 460 (l04)2 x 2 15,500 1 104 3 l,UuU,CuU ft lb lestsys'tlgglos 93310.92 .L:~.esla.os:9_ The aeeu losu Wgs eiVieeu into two yurts: that uue to Lbs utilitlss snu that sue to tne brluge cougonents. Ls SLOWL below, tee uesu lOpu Wufi found to be 940% per foot sue to the utilities use CLYfi per foot ror the rim iruer of tne bridge, a totel of l567¥ per lineal foot. nctuel size uLu weialts of consonants were obtaineo from representatives or tle college Builoing 3L0 Ltiliti s Lept. end Ilnuscape end Planning Dept. as follows: use... Cease; (Data obtleeu from P. Loonon, COlltSc eleutrie l enblneer) b conductor power cable of the to be uses 6.6s3g/it 4" conuuit for sLeiloing cl~etric oubles...lu.dg/ft .‘._'.. 0 ;"'-.,.~ W’, . Consults iur steum blobs (Data obtulneu ficm Al Lowell, college uesigb*nh engineer) Conduit gblbngnggggt 0.3. songector_ Keiint s" i:2" ls" sex/1t. ii) " i6 Q/lt; H 16;" ‘7 5 A' /lft 0 2a" 25 s/e" 24" llSr/ft. Weight 0: molueu fiber insulation (from Al Lowell) éofi/it 5 Floor System — T Eri—Lo; (Data from Curnegie Pocket Couusnion) Weight of Stsnusro a" use T Tri-LOK e 4" 0—0. witn concrete...........Esfi/sq. It. Investigation of Leeds, Lead Load Utility Weights Electric cables 3 conuuctor power ceble 6.65 fi/ft 4" conouit 10,5 5 cables @ 17.5 fi/It us fi/ft Telephone cables 5 cables e l5 #/ft (estimates) 45 ¢/£t 8" Return pipe 8" standsro pipe (A130 Hencboon) £9 #/ft lb" Conouit 50 insulation 19 water .23 lAO f/ft 8" I.P. Steam pipe 8" stunoard pipe (A so hundbook) 29 #/rt 15" conduit 75 insulation 58 steam .ll 155 #/ft 12" H.P. Steam pipe 1;" stsnoard pipe (A130 hanubook) 50 #/ft 2a" concuit ll5 insulation 78 steam EL_ 2 pipes o as? "-e §§E;fi/ft Investigution of Loner, Leno Loud Weiebthpf One Panel (Panel 6) Main Girder Flange 2600 # Main Giroer Web ll40 Railing zba Floor System dosO Floor Beam 190 Flange Sice Plates 5s Lateral Braces 108 Stiffeners 190 Fillers 106 Fecia 4U Total 7650 # Equivalent uniform loud per lineel foot of briose: Height per *snel a 76503 a 937 fl/it. _.._ -n—o... *c—v-o—fi-fl l Lengtn olfipsnelfi' o.ab Ft Investixstlon of lg:gp,fl§euu [can The weights of tne .noiviouul members were computes as follows: . ~ .. .. . ... I. _) 2-. ‘ A ‘, h. r—.v2~. ., ., Giroer sob e'c" x o/b" Plate o.sb It e e u /cu.1t. o/U,Q lo. ”'7" X 0/5" Plate 8.25 ft m d30§/cu.ft. 030,5 1'3 "X 5/8" Plots s.z5 ft e évOJ/cu.ft. 523.: 4'll§”Xo/o” Piste 6.45 ft b éQOf/ou.ft. bs6.s 5/5" Plute F9) (+ (f. 490a/cu.ft. 5'7 "x s/s" Plat" d.e5 it s 480*/cu.ft. (10.4 Girder Flange Sle g 101 5.:5 ft e lolg/ft. laud.0 Silafif 106 8.ub it e iusg/rt. 8f=.5 Flange Sloe Plste b" x b/ld" PlLte b.25 it s a90#/cu.ft. :6.e Stiffeners, Insice 5 5/16" x 6'8" Flute 4 ft.7 in. e 4vuf'cu.ft. / / 53" n b/o” Plate 5 ft. 7 in. 3 esofcu.ft. 63.6 -. - r... ' .~ r- I—. - «i . - —. . r , 7 stiiieners, ‘tSioe b2" x o/o" Plate e lb. 7 in. e-4so /cu. it. 60.7 Stiffeners, End op" x g" Plute 6 ft e 400»/cu.ft. 56.? 5;" X " Plate 6 ft m 4305/cu.ft. bd,8 Fillers b" X 9/16" Plate 4 it. 7 in. e est/cu.ft. 46.4 s" x " Plete 5 it. 7 in. e 490%/cu.ft. 14.4 14" h ;" Plste 6 ft e 430#/ou.ft. 71.6 Fecia 5" x ‘" Piste 4 it. 7 in. e 490$/cu.ft. 19.5 5" x ‘" Plots 6 ft e 4909/cu.rt. 25.6 Web Splice 3;" x s" x 5/8" A ngle 4 ft. llg" 10.4I/lt. 50.0 “g" h ‘" Plate 4 ft. ll; '1. e éQOfi/cu.ft. “9.6 s." x 2" Plate 4 ft. 115 in. a 4sc,/cu.rt. ;z.9 o5" x ;" Plate 4 rt. llfi" < 4°0#/cu. ft. 44.0 14" X 5/6" Plate 5 it. @ 4va/cu.ft. 55.7 5" i 5" x 7/6" Angle 5 ft. 7; in. c g7.x;/lt. 96.5 5," x H Plate 2 ft. e 430$/cu.ft. l8.7 Plate e éQufl/cu.ft. 9.4 __dl__ Curb angle 6" x 6" x o/al Angle 8.55 ft n 1% U./ft. lsc.0 Lateral braces 5g" x s," x c/e" nngle l;.7 it h 3.0 /it. 5:.9 Ieternination of TtreS‘ea, yioor 8,.tem anu fqur Legs Stress in T Tri—Lob due to 100 fi/su.ft. Jeanine on s.ss ft. szn. (Data from Carnegie focnet Companion) concrete fc - 4o9 ps1. (700 psi. cllowable) steel fs = 4606 psl. (13,000 ps1. alloteble) 7 l / §§§ I §§§ / §§l L.J 2’, §\\ / \ ‘/ 5Q i I ‘\\ I \\W / N ( 2 T 772-4% , Sioewaln live loao 100 fi/so.ft. Sidewalk deed load 58 Sioemslx loacinh 13s fi/sg.ft. Length of panel 8.25 ft. Uniform Siuewaln load per lineal fo Dead loao of flo.r beam Utiliuf loao pcr lineal foot of brioge Length of panel Utility loao per panel EquiValent uniform utility load per Shear in Floor Beam: ct of floor beam 9.20 5/th 6.20 ft. L' .. 0.) 7/ # gs; Fth. LUOvD-Z: :.-/’ i‘t. lineal foot of fluor bee: . ..‘ ‘-‘ — .— u, 7: 33 V'rl - Zén'vOn-‘i ‘1. 9 - 9,0;'U 74‘ S = = 9,03% = 1,500 psi. (allowable 11,000 psi.) moment in Floor Beam: M _ l/BLOgO x 81 _ £0,i7c ft — lb so,475 - lc,650 psi. (allows ble is,-oo psi.) l'- ' ' I n D - :31 a l-‘l I; ’7 1 H Determination of SLTquML, Floor Beam Connections . ‘sI " s" ""I .""II . ‘l'. ya I..°. g). H." Q. 'I ‘ ‘.~6..'.‘.0'-"..° 2". 2" I‘ e‘ .‘I . ‘J' “"4““: .X ' I o. n I. .. u'ur'\ .. o. ' ."..'pv‘ F/ooy Beam F loor beam to stifiener connection: End reaction of floor beam (sneer founo on previous page) Weight of curb angle v = Length of weius = 2 x 4 15/16 a 9 5/8" = 9.63" \ CF trees of welds = S = V = C 255 g_§ a 5,610 psi. (.7u7=5/8}i .707 x 9.65 x 5 Allovuble (AlSC handbook) 15,600 psi. Stifrener to filler and filler to girder web connections: Length of welds = z x 4 x 5 = Z4" Stress in welos = S 2 0,2;: x 4 a 2,170 psi. J- Allowable (A150 hendbook) 15,600 psi. “;"H«u£*fw. v ;“3 .‘ 7’; ..,. N £33,356 (fit-.35.? -‘ 9,099 I‘Jl 4. a. U 9,;ab Li/“JW‘H Determinstion of stresses, Msin Girder fieb .. 71 The web of tLG main girder Wes designed for adherence to Spec. 11 and 27. The shear Wes not a deciding factor, as Siown below. The uniform locd, dead and live, is 900 (live loud) X 1867 (deed load) or £767 lb per ft. Sheer at end of bridge : V : 2 W1 : g 2767 x 104 = 145,884 # Shear for each girder : 97 = 71, 94; # Stress due to sneer = S a 71, 94: = 2,864 psi. 6 x 1: x 3/8 The minimum web LmiCKHwa is 0/8 inch, according to Spec. 11. A s Spec. :7 States, the web must be more than L/EU, in which D is the distance between flanges. Since the width of tLe web varies, D will vary from 41 iLCheS at the center to 59 inches st the end. As checked below, the web thickness does not follow the Specifications at the end. this discrepancy exiits only in the first one—half panel and is minor. at end D e 20 - 59 2r 3 .55 in. at center D s 20 - 41 e 20 — .52 in. actual web thicKn ss 5/8 in. = .075 in. The width of the web, according to Spec. 10, should be not less than 1/25 the length of the span. This is setisfectory, as shown. depth ratio 1/25 x 104 = 4.16 ft. = 49.9 inches minimum depth at center 4 ft. 6 in. = 04 incnes Determination of Stresses, M ianirder Flsnge The flanges were analyzed according to tie moment of inertia method, as specified in Spec. :5 and 06. Bending Stress : Homept and center (1/8 W12) — §7§7 (104) B 13 = 17,700 ps i. Lepth or seetion fires of Section dibéxgb.00xt According to Spec. 8, the allowable compressive stress ‘5 18,000 — 5 L2 b 2, with an L % b ratio less then 40. With L _ 1&0 incnes and b - 12 inches, L ; b a 10 and the aliowsble stress is 17,500 ySi. gs found above, this stress 5772 WF/é/ Quint/c Trace "*‘ (ML: «M. (i 14/65 \A/c/OG “ff/[cc , :0” 0:13" «31¢? 6 ”(LLJ J'lfi/ 5 '94:. Jig/L 4% "£41 "Ac. ’1 7 F 1.2:”, is exceeded. TLG possibility of this girder feilinh beceuse oi t:1s is siight. Only all the flunge end 1/8 web Wes considered in the moment of inerti; KCEIOU. By considering the entire web as taming bendini, tne stress would be below the allowable. This is nOt according to tL‘ specifications, however, end the author would not advise using sucn e n; r10." de p tn of section a t tie center. 5n eitre 2 inches in the depth of the web would not upset the rest of the design and would bring the stress below the maxi mum .illoneble. De rminetion oi Stresses, W in Girder Telo The horizontal increment of slee r ives computed end tlfi 00n160110n is chees— ‘1 ed against tnet. A Sample computdtion follow ROI. :3 V [if = lOUL) ,i-f/in. . (1.x 1/0»- > H“ Stress in welds = 6 x 1000 = 5,0;0 psi. A110 avabie (1.1.C.C. hw' ndbodx) 10,000 psi. Determination of Etres 1"} \.- , (14""W, . e-, etiiieners According to Spec. 31, tne OUt50&nQinQ legs of et1iiener 510010 be more than 2 incnes plus 1/00 the depth of the girder end SLOUlQ not exceed sis; teen times their th1csness. Thus, the length of outstanding 105s must fell between 5.8 inches and 6 inches, es computed below. {11 stiffeners f e11 in this bracket, tieir siz.es ran 1ng from 5 0/16 to 5; inches. 2 x - 2 x 5d — 0.8" O 5' 0-1 It! 16t — 16 x 0/8 — 6" Stiffeners are placed every 4 ft. 5 in., Well. b low the depth of web limit of 4 ft. 6 in. The end stiffeners are designed for bearing on their outer 1135503 only, as stated in Spec. 50. I; l 5g" x 2" plates 5.0 83. in. 2 - s." x .~ Plates 5.75 5.. in. 3 — b" 1 a" Plates 8:u__sd. in. liJQI/b S\i. in. The total lOdd on the end stiffeners will be one fourth. The total weight of the bridge or 71, 94; 00. Bearing stress - 71, 0£s # - 5,;25 psi. 10.7: ed. in. ellowible 18 000 psi. ( , Determination of Stresses, lateral Bracing -+————815” The Specifications state that luter 1 bre01ng LLOUiQ be designed for a wind load of 500 pounds per lineel foot. (Refer to Spec. 7.) flech ldterel would hold the wind lend of one penel in eitner tension or compression. 500 f/ft 5.25 ft = 2475 g per penal There would be no denser of bucxling under this 10nd. The Stress was com - puted for an eccentric loading as SLOWH below. in S = V §_Lc /1 7: T ‘ “fi75 §_s47s x 1.35 X :.65 a 4,870 psi. The allowable stress Wes computed from I Spec. 8, the formula for riveted c01- unns being used. L/r , 160 IN M 1‘“ I" ‘wmmmmmmwnmummmmwwfl s - 15,000 — f (11.6s)e 1.07 s - 11, 700 psi. 4 1" . 1.11 I)! I'll-ll...) .l A DGtCTmiDLLlOH of Stresses, Railings As per Spec. 1, the toy of tLb railings is 5 feet a :OVe the sisew in. also, the r iling is to be oesigneo to withsthnc e v rticel force or in» bounce per foot enc a horizontsl force of 150 bounns per foot, as sheen below. loo “fl /6Z>%fi. E;* éiéhffifl 5’4 The unit SLrLS.eS in the railing were conputeu as follows: Shear in reiling: V g ldO x 8.35 : 742.5 # Stress due to Sheer:3 a V a 74:.5 = 555 psi. I &.&O Moment in railing: H - 1/8 180 (8.25)d : 1550 ft. lb. 9‘ 5 =_£g - 12 x lebO x l.5 - 9,150 psi. 1 - 5.017 (allowable 14,500 psi.) "I I The strength of tne railings enhen‘eo Quite suiiicient but the eels r') '1‘ K. V ye ( checked as follows, consicering only the horizontal Lorce: (allowable lb,60b gSi.) M: I, 8:14.. .Lrlr ‘8 CL‘ Determination of Stresxe:, Lnu Refer to Spec. 15 to do inclusive, for tne cesign o; the enu bearings. Tne sbeciricetions are follOch Very well. ExpenSion must be allowed for a t the rate of l; incnes for every 10b feet or 1.5 inches for tnis egan of lu4 feet. 5 inches are allowed. Bronze slicing expansion bearian ere province. Tie anchor bolts prevent any leterhl movement. the bolts extenu into the masonry the required 13 inChes she a 4" x 6" x 5 5" angle anus to their sta biliqy. The girder is SungrtEQ on metal plates so that the bottom cnord is 6 incies above the bridge seat. The base plate is 15" x lag", givinb a preshure on tLe masonry of 15 X l‘:1'd.8¥;. ill. (allowable 1000 psi.) Summary of Stresses The unit stresses for each member, found by assuming the apglication of a live load of 100 pounds per square foot of sic-waln area, are listed below. The allowable unit stress, according to the A.A.S.H.O. specifications, are liSted Opposite for comparison. n ll strLSSes are in pounds per square inch. Member under consideration_ Stress as found Allows tle stress T Tri-Lon Flooring (concrete) 469 700 (steel) 4,696 l8,000 floor been (due to shear) 1,5"0 ll,000 (due to bending 15,650 16,000 Floor Beam Connections 5,610 l 5,60o 4,170 15,600 Main Girder Web (shear) 4,654 ll,000 Main Girder Flange (bending) 17,790 l7,500 Kain Girder Welds 5,020 16,600 End Stiffeners (bearing) 5,2s5 16,000 Lateral Bracing 4,870 ll,750 End Bearings (masonry) 550 1,000 (‘H‘ 'n I. I." ‘ "v‘f‘ :7 C Ji‘ubiJ -k-'.J..'\IJ.J' In answer to the question, "Lo:s this bridge lulllli the reguired spec— ifications?" the answer is yes. The iourth edition of the speCiiic tions calls for a live load of do pounds per scuare foot on sieeralns and males no OLLLT statement concerning footbridges. From tris, one mimht conclude that 55 pounds per square foot snould be used for “his brings. The allowable stresses are not exceeded with such as applied load. forever, as explained in tle in— vestigation of live loads, the author felt that tLe statement concerning foot— bridges in the tnird edition oi the Same SpeCiiicatlons erould apply to tnis case. As it turned out, all unit StreSSes were very Sati&l&Ctory, sa ve for LLS flexure stress in the main girder flange,. A comparison of the allowable stresses, according to the iourtn edition of "Standard Specifications for kiaLWdy bridges," end the unit stresses round by applying a live load of lUU pounds per sundre fOUt is snown on the prececding page. It will be noted that the unit stress in the main girder flange is a bove the allowable. i live lo;d of st pounds per sguare lOot could be an lied with- out exceecing the allowable stress for the flange. It is pos ible tilt the live load used by the autror was too high. A more intensive nnowlcdge of the os— velopment of this design will present the poscibility tnat the bridge was slightly under—designed. The designing engineer used a utility load of 700 pounds per lineul foot of bridge. The utility loading as found in this analysis was 940 pounds per foot. There is quite a difference there and could bring the unit str ss in the flunge well below tLe allouab'e. The reason for LLB large difference in th tto Utllltd loads in CVivtht when the designing conditions are Known. The designing engineer did not have a definite Knowledge or the tgpe and amount of utilities Brat were to be put across. lhe pipe sizes and LJpES nele changed seVerel times after the CEbign was started. The utilities Shown on the plans included With this analysis are not exactly the utilities which the bridge was ceSigned for. Tne engineer con— sidered the oranges minor enough and the bridge OVer—Ucblgheu enough to carry C, ‘3'; 1137‘ HAUL/1.. L‘J.2.L‘L the extra utility load. Strictly speaning, tnis ens not so; but the resulting over-load is so slight, and tne possibilitj of tnc structure ever TECLiVlL; such extreme live loads is so rare, that tLe engineer was dulée justified in not cnanglng his design. This will be ftrtrer borne out by tne feet tnet tle present plans represent a furtner change in tne errhngement of utilities. The author offers no explanation for tne n_merous cnanh~s. Except ior tn: gird r flange, tne QGEan Ioliows the Specifications duite h satisfactorfiffiThe welded construction allows ample strength for all connections. The secondary members are over—designed in order to fulfill tne reguirements of the specifications cone rniig minimum sires. ConSidering tnat a primary purpose or tnis analysis was for the benefit of the author, in obtaining experience in structural OGSlgn and formal reports, tne time was well Spent and tne r>w res, were more tnan expected. The a utlor was quite enlightened concerning the so Clnl problems present_d by iootbridges. This problem brought out quite clearly, tte importance gnu difricult, which ariS‘s in tre cnoosinb of splcificltions end rpplisd loads. It is regretted tnat all tne "little tnings" earned by the uutnor in writing this could not be presented on paper for tne b;nefit of others. Excerpts from "Standard specifications for Highway Bridges" l. flailing§:_ S“bstentidl rsillnbs along eacn side of the bridge shall be pro— vided for tne proteCtion of traffic. The top of tne railing SLcll be not less tnan 25 feet above tne finished surface or the roadway adjacent to tne C‘lb, or if on a sidewalk, not less than 5 feet above the sidewale floor. Railings shall be designed to resist a horizontal force of not less the n ’150 pounds per linear foot of bridge, applied at tne top or tne railin , and a vertical force of not less than 10o pounds per linear foot. 2. Dead Lead. Tne dead load sn ll consist of the height of tr (D 5 “Bl“; CCU 1‘8 COED— plete, including the roadwey, sinenalxs, car tr one, pipes, concuits, cables, and Otner public utility services. The snow and ice load is considered to be oilset by an accompanying de— crease 01 live loud and impact and enull not be included eicept under Special conditions. The following weights are to be used in computin5 the dead loud: Steel ......................................... 49o lb/cu.ft. Concrete, plain or reinforced.................. lbU lb/cu.ft. Loose sand, earth and gravel .................. lOO lb/su.ft. Compactcd send,earth,gravel or byliJSt ........ lbO lb/cu.ft. 5. Live Load. The live load snnll consist of the Wbight of the Lp‘liefl moving load of vehicles, cars or pedestrians. 4. Sidewalk Loading. Sid walk floors, Stringers and their immediate supports, shall be designed for a live lodd of so pounds per Square feet of sieewelx area. Gircers, trusses, arshes and Other menbers Shall be designed ior tne following sidewalx live load per Square foot of sidewall area: (for spans over lOu feet} p - (so x sooo) (ss- ) 'tt‘“ ou *U ll live load per SqUarb feet (maiimum 60 psf.) L = leaded length of sidewelx in feet. fl = width of sidewalns in feet. ~&-—-— lixcerpts from "Standard figClelCnthDb for Highwag brig es" £5. Impact. Live lead stresses, except those due to Lingual; loads and centri— fugal, tractive, and wind forces, snall be increased by an alienance fer dynamic, vibratory, and impact effects. 6. longitudinal Force. Provision shall be made for tne effect of a longitudinal force of 10 per cent of the live load on tne structure, aeting 4 feet a bove tLG floor. 7. Wind Loads. The mind force on tne strUCture shall be as umed as a MOVlng horizontal lOud edual to so pounds yer shuare fOot on i; tines the area of the structure as seen in elcVatlon, includinb the iloor system and railings, and on one-half the area of all trusses or girders in excess of two in tnesyen. The total assumed wind load sn ll be not less tnan boo bounds per linear feet in the plane of the loaded enord and l50 pounds per linear foot in tne plane of the unloaded cnord on truss spans, and not less tnan boo sounds per lineal foot on girder spans. 8. Allowable Stresses in Structural Steel and aivets. axial tension, net section .................................. l8,UCO psi. Tension in extreme fibers oi rolled shapes, girders and built sections subject to bending .................. 16,0no psi, Tension in bolts at reot of tnread .......................... l ,bUe ssi. Axial compression, grass section, stiiieners of plate girders ....................................... ld,0eo psi. Columns: The permissible unit stress in concentrically loaded columns having Values of L/r not greater tnan 140 na y be conguted from tne follOWing approximate formulas. hiveted ends .................. le,UUO - ; L2/r3i Pin ends ...................... 15,000 — l/d lL/rE L = length of member, in inenes; r = least radius of gyration. Comprescion in extreme fibers of rolled snapes, girders, and built sections subject to bending (for Values of L/b not greater than 40) ....... ld,5oc - 5 Lz/os d. A llowable Stresses in LtrUCLural Steel and Rivets. Allowable compression in splice material, gross section ....... ld,oob psi. Stress in extreme fibers in pins .............................. s7,buc psi. Shear in girder webs, gross section ........................... ll,UCd psi. Shear in poser—driven rivets and pins ......................... 1 ,soc psi. Shear in turned bolts ......................................... ll,O"U psi. Bearing in pins ............................................... £4,0bo psi. Bearing on power—driven rive s, milled Stiifeners, and Other steel parts in contact ................................ z?,UtU psi. Bearing n pins subjected to rotation (not cue to delleCtion) . l;,oeo psi. Bearing on turned bolts ....................................... zo,eou psi. 9. AllOWable Pressure on Masonry. Bridge seats — under hinged rocaers and bolsters (not subjected to high edge loading by a deflecting beam, girder or truss) ...................................... 1,030 psi. The above bridge seat unit stress will apply on'" nnere the edpe of the bridge seat projects out at least 5 incnes beyond edge or the sl0t r plate. Otherwise, the unit stresses permitted will be Yes of the a bove amount. 10. Lepth Ratio. The ratio of the depth to the length of Span, tor plate girders, shall be not less than 1/25. 11. Thickness of Hetal. The mini” m thickness of structural steel Shall be 5/16 inch, except for fillers, railings and unimportant details. Gussets shall be not less than 5/8 inch thick. Metal subjected to darned corrosive influence snall be of greater tnicaness. 12. Strength of Connections. No connection, except for lattice bars and hand- rails, shall contain less than three rivets. All connections and s" whetner in tension or compression, shall be preportionCd to develop tee full strength of tne members, and no allowance in excess of 50% shall be made for milled ends of 00m0T€Ssi0n members. fiplices shall be as near the panel points Excerpts from"5t;ndsrd SJiCllngthnS for ri ewe; ergégi.” as prscticsble and, in gcncrel, shell be on thet side 01 the p nil point Hnluh is SUbJSCLBQ to the smaller stress. 15. Cong; SLiOH Members; C ngression members Shell be U:El;fl€u so tnet tne metal shill be concentrs tea as fer es feesisle in the webs end ilnnaes, and so that tne center of gravity or the seetion m;y be as near tne center line or the member as yrscticsble. The thickness 01 web plates oi compressive members shell be not less then one—thirtieth of the transverse distance between tne lines oi rivets conneCting them to the flinges. r'he tnicznesu of cover pistes of compression members and cover plctes on the compression ilunges of plate girders preferably bLnll not be less then one—fortietn oi tne transverse distance CCULCCH tie lines o: rivets connecting them to the ilengcs, but tne minimum me; be one-iiitietn o: tris uis — tance, provided the Width of the plots between the connecting lines 0i rivets in excess of forty times tne tnicknews Snell not be considered as eriective in re— sisting stress. 1%. Outstanding Legs of Angles. The widths or the outstenuinb legs of sngles in compression (except where reinforced by plates) Snell nOt exceed tne following: in girder flunbes enc mdin members cerring axial Stress, tWelve times the thicnnesn In bracing and Other secondary members, siXLeen times the tnicnness. 15. Exnension;_ Provision Shull be mice for engsnsion and contraction at tie rate of 1: inches for every lOu feet. the eigension ones snell be secured against lateral movement. 16. End Bearings. Expension ends Snell be firmly secured against lilting or lateral movement. Fined bearings sn ll be iirmly shonored. Spmns or less then 70 feet me; be arrenned to slice upon metsl plates With smooth surfaces. Scans of 70 feet or more shell be provided with rollers or rocners, or else with bronze sliding ensenSion beerin s. & Excerpts iron "3t negro sptCiiications ior hiiixrg bridges." 5.. 17. Rollers. Expansion roiiers SL 11 not be lass tlan four thLbS in cicmeter ior spans of lOu feet or lees, and this minimum shall be increased not see than one inch for each additional 100 feet and proportionally for int-rmediate lengths. They shall be connected by substantial side—bars and shall be effectively guided ls to prevent late‘al movement, snewing, or creepinb. The rollers and bearing ‘Q 80 $ plates shall be pr0tecteo from dirt anu Water as far as pos_iblc, and LLe con— struction shall be such that water sh l1 net be retained and t:at LLS roller nests may be inspected and cleaned with the least oifiiculty. 18. Peuesta s and Shoes. Pedestal: and shoes erll be used and be designed to secure Tingle and stability and to distribute the reeCtion uniformly over tie entire bearing area. They shall be mice preferably or Cest steel or structural steel. lhe bottom bearing tioths shall not eiceeo the top as rin; aiuths by more trnn twice the depth of the pedestal and, when involving pin bearings, this depth shall be measured from the center of the pin. lnere built pedestals and shoes a re used, the web pl tee and But an.lts connecting tnim to the base plates shall not b) L} b less than 5/8 inch tnice. If the size of the pedestal permits, the webs she 11 be rigidly connected trinsversely. 19. Anczor Bolts. Anchor bolts for true es and girders s. 11 not be less than 1} inches in diameter anu shall extend into the masonry not less than 1X inches. flashers smell be used under the nut. incuor bolts subjected to tension, as in viaduct towers, snail engage 00 per cent more masonry than is re,uired by tre uplift. 20. Sole Plates. bole plates of girders and trusses shall not be less then inch thick. 21. Masonry bearings. Cirders and trusses on masoniy snwll be so supported on metal pletes or pedestals that the bottom ChOlQ: will be above the bridge scat, preferably not less than 6 inches. Lnocrnts from "etenu rd bgtciticstions for nthWuJ brldwsi." CI" 2e. Floor figstcm. FlOUI—DCam: preferably snell Dc st TLLLL Lholzfi to tnc ruases or main SiFUCTS end sn ll be rigiely LODHiCLLU LLETLLO. holes FlLL Lloer sJStems preferably snell neVe end floor-beams. [non end iloor—benns firm not need, tle end p nel stringers sh ll be secured in correct position by end struts Securely con— nected to tLe Strirbers end to the muln glIOch or trusses. lne end pun l lateral brecinb shell be rigidly attached to tne mein girders, or trusses, end Shtll be attacncd to tnc end struts. 25. lininum Size of Angles. Its smellest angle used in brecinb biull be a x 23 inches. 24. Lateral bracing;J Bottom laterel bracing smell be provided in all Splns ex— cept l-beem spans and decn plete girder scene of 50 feet or less. 25. fibrousn Plate Giroer Spuns. Througn pldte girder spgns snell be stiffened against lateral deformation by means of gusset plates, or “Lee braces altn solid webs, a ttacned to tne stiffener enbles and floor beans. These braces generally shall extend to th-w clearance line. If the unsupgorted lenétn or tn; inclined edge of tee gusset plate exceeds 60 times its thicxneSs, tne gusset slate snull have one or two stiffening ungles riveted along its edge. 26. Design of Flute Girders. Plate girders shell be proportioned by s s using tbet the flan2es are concentrated at ”heir canters of gravity. One—eixrtn or the gross section of the web, if tne web is eiitctlvely spliced, me; be consiuered as flenge section. For girders having untennl seetions, the montnt of inertie metnou smell be used. 27. Binnie Sections. The flange angles Slgll form as lerge a pert of the area .L. of the flange as prdcbicnble, sice pletes stall not exceed except where flange ales angles exceeding 7/8 inch in thickness otherwise WOUlQ be reuuircd. The gross urea of tne Congression flanne snnll not be less than tne gross area of the tension flcnge. Flcnge plntes snull be of eoUul tnicnneSs, or sLdll decrease in thickness from tne ll nae uncles outward. No plute snnll rev; d thicfiness rfire-titer tlc n 'r‘ ' 7" s' 4 I: "2,. yo 3 L‘ ‘W'flj’ flux f ~18)- J ) 5? a J}! .F “‘5 . I “I": :3 «15's I 2‘! ,I I it}! .- 3-" I O ”.2 ‘ .' i! 0: D 31'}! W?" 7- 4"” 1" -. '- ' . . - . m...- a—._"\ ; 3"“; .3: ~1's... - - t. - I - , " _ “L " . «o I 5"“ 2’? 1:1?" ('11 LL: 53g I 5 I we ' .i I! ‘711-1'." b IN" 6 l ”‘7 1" I" - -: ii'iAA I 1 lfi%” . .I_ :3; I" .. . A V .. - ’51“; I. "-" rs ":34-~‘;._:.-_ . ...:‘- .- .._ ‘xmr‘x- .. '-n:1: 5; :3 . -x‘.‘ '-—, *- -‘_~—-‘ .-._- _;_ L»; ~g;9_... v.3; N '.‘ o“ . I. f" . .»- 1"“ 30 ft 1 .- '15“ A . §\ _. o l “- A). .‘f: - O , — 1“ y" _" . . '.. 5:.“ .nw “ x—. in?“ - ¢ .‘ 1:53.. .,. 1 1t ." I i G l ,1 321712;. 2: f. t’ ,‘I‘WInC I f C " . 3’3“ 1' 5 '1 'ul :5“ " . ~ w . . ‘ rt "f... ‘2 -_ I; .. .. ““rpfi-v‘g: r2322”; . {t «W? “4.. '-~; - 9. --- 11'!- ‘ n Ht}: l... L“. VI.” a... A ”:5- flw':§: 3‘1. , . Isl." “"a. i. ‘- ' r¥’- » .5 . cw DI. u If"‘ 0 htlflfig’um '5 *i‘ r.I-’ a \m hi I a .. 3‘ . _‘.t- It C(‘ ., I ‘iu J Jenna fr‘v: .1. s3“? 9-“‘" n '7. 1. JV; lb ‘3, ‘1. "E: -, _ c” :8, ' . A“. ".LE:_.L wk“:- :3 2‘- . m2 ' V "“12: . ‘ a f, -‘ V. W *4. :2 .xfir -l .73 ., _. a}. ~:.._.‘:$‘1v“ . Quiz-.L I .‘ 1"I rm: ,. .2..- .4 r v»; ' rial; \ ‘ ”-o"-._._-‘AA 91’" -/.-..«.I '\ lxcergte from "fitenoero So ciflcetionc ipr Li Lueg Tricyee." A H-.. A __2 27. Flange Geotione. thet of the flange angles. If tLe flenge pletee ere usec, at lenet one plate on the top flange shall extend tne lull length of the giroer, except Knere the il'nge is to be covered with concrete. Any equitionel ilengle pletee ennll enteno et leeet one loot beyond the theoretical ene, end there enell be a sufricient number of rivets at each end of each plete to cevelop its full stress Velue before LLQ era of the next outeiee plate is reacteu. £8. Thickn:ee_9f Web_Plites. Tne thicenese 0: web pletee, except trose to be —._.. T\ encased in concrete, Snell be not leee teen L/uo, in which U is tie eictence in incLes betneen flanhee. X9. Flenxe_§fggfifi§l_ Splices in flange p rte en;ll not be ueeo except b; eoeci l permission of the engineer. Rot more then one bnrt enell be soliced at tne seme cross-section. If practiceol , sollces eblll be loceted et boints where there ie an excess or eeCLion. The net section or in: eblice Skhll ex- ceed by 10 oer cent the net seCLion of the pert SgllCeQ. flange engiu splices Snell coneiet of txo englee, one on each siee of the girder. 50. g§§_;plgce§,_ Web pletes shell b; Splicco eymnetricelly by bl tee on each siee. The splice smell be equal to the web in strength in bOLn excar enu moment. lhe splice pletee for sheer Shell be tne full uepth or th Eiieer between flenmee. In the splice, there en.ll be not leee then two rows oi riv- ets on each site of tne point. 51. Egghfti§§§p3r§4_ Over tne no beerinbs of glete gireere, trere Snell be stiffener eiglee, tLe outeteneinb legs 0: nLi n ensll ent-no as nearly es bra c- ticelbe to the outer eege oi tne flenge angles. fine etixienere Shfill be pro— portioned for bearing on the outetineinn legs of tbe flenge angles, no ellowa nee being made for the portions of the legs fitteo to tne fillets of tne f lenge angles. fine stiffeners Snell be urrungeo, enu there exill be SUlLlC;CHt number 0 of riVets in tLeir connections to the web, to transmit tne entire end ree cticn . . . . ._ . I _ . . ... ,. . H. 41...”... . . ......ivH. WA? r. . .. ......... . .. H...» .. . . . ._ .... . . H: . ...“. _HH.... ..H.... . .....er. 1...... filth... Hymn“. .....HHH... ._“_.".>H....: 3%.... ._.HLHHH. tut .....HHH 2w Hflipfllfih mg... mg... .HHF‘ 3.. . :.. ”$.12... “:3 ““53. .. :WA’; «HKWHH.JWLPVHWHH HaeHmH H335HHJHLWL3331‘ $1...unhk»..fl «.er Inn: Fa. Jflhlhm Fffiafih EEK“ . 1‘“. .v ....‘H«. i ._- 32:21... .H, . MHHHHE ..a ._t . . n . «...... ... .. 7...... ..... .... .. f... H... .WHM 7. .....H... . .... . 1.. H......... ...... . .....:. . ....H..... ,. . ...L... . ... ... . .. ... ..H c. . ....H...__ ii... ......EHeHHH. .. H F ......H. . {as}. ...... .HH Here .-.?Hee. ....Huhm..2er%€ .. Emu... ......E. B.Fffi..§. ....m....H: {Euwrlfizz .... . . . I... . 5;... H1... . nu .. ..H . . :mv ...aflw H.3.H.Hu. .....t .. . . ... ...... 1 .131.1+JI1 H._...HHHH ..H. .. H u H . ._. ...i H. a”... . 31“”. a . . ...:sT... . .I. ..q... r... . LHJ. ...D . ....w. :3...:....- . ... 1.me ...H.. M 3...... .£.H.H.HHH...:. 2... .. 1.1% _ H . ....H we... . ...... Hm. : ._.H..._H ._.... ...w . ...“ a Is”. a; m... fir»: i m HHHFVWmNIrL..MM— .wnr§._ ...I—L~....“b¢..Aw.e.k1.:ra......*w.,.k {H .5 L51. . .‘T. ..IZI . .... 1‘6.- t. ...U. C ..C H U _ C .... 0.. ...... q... Tu n g H .... C .0 C 6 d n H D .L -Tu :H O , .. [TU K... ...“ C O G. l 4L . P. Wu CH .... H ... ...l O Q, T i 0 w . CL ... U0. . m L H. U W .-H .Q .3 K ..-.H C C .l e e i O in u L c t o. t 0 rd , A .J S 8 .1 .TV .1 €. H. ..I: in“ Mr.“ O m. e. no 1U . TV 5 O H u n. . l U n E G L .nl Hrv n C U; _- n S O , u. 6 C a 1... 0. ... 4. .1 e. S ..I We. Pl 1 u .L V. .l _|._ e _ .1... up; 4.0“ .1. HIV. b HIV 1 H u ....H l ... Nu H o C u C i. n d . D n L ... l “I. .U . L e . In. NILH O D. ....IH TV w...“ -...» C ....1 mm wt... Cu .1 e ..I. .0. ....U by C S I ..H u .. a I X s n C S O ... C O n ..l C S h m C -11. t . b b .t ...n , i 0 . H . 6 l - .l n C l o m. ...... W. l 1“ O CO 4.1V CU ..vA— n , ..L Cu .51. :1. . S E. C. C . l . e l e V C H l S . u +u r .H. -... r H ._I._ r d e m .h -. M r H 09 O .....H ...U H s n n e. m u H C e e . r. a... f t .. . H 6 l l ..b I 40 Q . .-..h . l ....H .... U a .-.. H o Hi L O 6 +u I. . S c u . n. D Q +w H r E L I m ,. ._ H 6 . 8 O C .. n . n S t . l C "......“ r... n . ...u o F .r. m ....i n. i o t r n O .1 .1 u e .l r .l r ....H S r C U ”l .H.U a m H l i ...H . o, . e T l C l O S b C . -..... .... 1.. .1 Q L. o D. 1L r _ I H h T. n S h C E +u .l ...... it in. C o o n... .H . . l O 3 O .l ...... r HD .0 +o 5 LL .3 0 .0 T' I ; '~. . ‘I I. J‘IH ‘7' H) .Ar-\--). 1:4. C'ancar' Specifications for Lifinwcy Driuges ccopted b5 the gmcriocn LScOCiction or State Himhwa y O.ficicls, EOurtn Loition, 1344 Stccl Uonstruction by Lie nmericcn ILsLitute or Staci CORSLrbCLiOD, Fourth anc fifth Luitions Llcments oi ercngth oi Latcriuis by Iimoshenxo ano LLCUuliOUQi, Seconc hoition Carnegie Pocxct Companion by Carncgie Steel Lo., 1954 besifln by Steel Structures by Urcunart and O'Rourke, rl‘st Loition, chO .4. .- cm... .- «5'1. “‘21— ‘ ‘: I I1?” _". "6+ --- :« ‘ ....‘5‘:__-}:ST.-‘_ We: 1.327;: r - 4;... '.r?.l I_ .‘fii‘: fl 1 H: g‘H f'fi‘ :‘ a: . .. 54-..; a, :5. : L1": . 1, 1 2J3» .; I . .‘ ‘:' ' t'i‘i' -.' g H "a. . I. j ' 321“} - i >“,« _ .17: a». I .it‘ - Jr. t’f ‘2‘“ ... I'M; it: . . “ ,l‘ 1W .1 . - . fl s“: e 7 420} J?" I ..y " db. - .‘ "..i ti “f? 1“! ‘h P 91* .A C ‘D ' s r , ‘ :17» . .‘ ‘ 3‘ I 1"”; .42. C " .rlk’ _ .9 -e 1- . o ‘ 7 "' ' , ’ u—‘qfi‘ ”Vi.“ ‘_ _. ‘5" its: ._;::_ h"; 7 If; *7; C . 74' :l I -"' '1‘. ~ 1' .552 > 41 .. i”— '.;. . 3"" Hat": ":1 2. r l | ‘ ... O "t‘ I II “I 1" 4|. I . I... ' q"‘} HICHIQ 9N ST QT E UNIV LI BRQRIES |||| III 312953002