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Home My WebLink About[1889] - Craighead BridgeTNr PITTSI~i ~ RGII 1~RIDG1; C~ 1~IP.a\1' leT~I.~OI~ & ~~TCI~~~x~.~'T c.~ ,.~o~~hE ~Jifitsbur~h ~r• ~ l ,, ~ i i. '~~* F ~~yy~~ .~~~- ESTIMATES, STRAIN SHEETS ANO PLANS rUlt\I~'IIEn. ~~' -'s)-i~J~ PLEASE NOTIFY US OF ANY BRIDGE LI:T'CI \ I i~. ~P~CSFSCAT20N~ Foy the ~~pe~~~~uc~urie o~ ~ ~~on~h~ Iron Ig~~~~ Bnld~e, GENERAL DESCRIPTION. The center lice of the bridge v,~ill be at au angle of.-._ ..... ........ .........._ degrees tsith the face of abutments. The Superstructure to•cousist of.. ~ r. _._~'._-......Spans, ~ v ~- ,_.... feet, _ inches long, c. to c. of end pins, and to have ........ !`3" ~ - .."~_... _. ~ ` _ _ _ feet wide in clear, between 'I'rttsses. The Trusses to be _.... __. Roadway, _ _~,oJ.._ feet high c. to c. of chords, and each 't'russ to l:~e divided into ~ _ .._ panels . / ~- ___feet ___ inches long. 1'umber of side~ealks, __ .. _ -_____ \~"idth of side«-alks, _.._ __ PROPORTION OF PARTS. The I3ridge to be proportioned to carry a load of ~~~ pounds per__.~. _foot of floor surface This load cousiderecl as a moving load, gradually covering the span, starting from either eucl ; auei the utasimum strains caused by the above moving load and the wz+;teTiT of the structure, shall be taken to proportion all parts. All parts shall be so proportioned, that the maximum load shall not cause a greater strain in tensio~t than /. - ~ l - per square inch, net section of the member strained. tior in conlpression a greater strain than that determined by the following forvmhe 10'~~~ for posts with square hearings. 12 1--~- 36,000 r2 l~'00~ for posts with one pin and one square bearing. 12 1-~-- ::'x,000 rt _ l~'U0~ - for posts with pin bearings. 1 1-- 18,01111 rz L representing the length of post in inches, and r the least radius of gyration of the section. Rolling 7,oad per Panel _ . _ _._.__ 13ridgc «'eight per Panel , .,,. _....-. GENERAL DESCRIPTION, .......... Top Chord. Top chord to be made of ___ ~~:. __ __chauuel bars -P 1C___ ..z.4...c. {,..:. ~ „-~ . _ ~ P~. ~/~ . _.........._. with plate... ..._._.. ~ _ _ _. iu width, riveted to top flanges with...... `~/`t. _ _. _rivets, spaced about __ .,.. ~ ..... .apart. Hower flanges of channels to be connected by........._,~-~.......-........_ plates, spaced about......._........_............_..._........_apart, or latticed. Pins and pin bearings to conform throughout with the requirements of strain sheet. The connection of top chord aucl end post shall be as shown ou plan _.... - ...... _____ . _. End POSts. The end posts will be composed of_......,,.~.,.,,-...,.....~ ...............__...iuch channel bars constructed in the same manner as the top chords, ........._ _.... ...... _ . T~Ower Chords. bower chords to be ece bars, having die forged heads bored to exact length in pairs. P;ye bar heads to he so proportioned that if tested to breaking the bar will part in the body and not in the pin hole. Pins. Upper and bower Chord Pius to he accurately turned to size, to match the holes of the several parts of the 'Trusses through which they pass. Intermediate Posts. Intermediate posts to be made of two chaszuel bars, latticed, or of ...,.,.,.,_ ............................. angle bars latticed, as specified on straiu sheet. Diagonals. Diagonals to be eye bars having die forged or turned eye heads drilled to neat lengths and made of best re-rolled iron, as per straiu sheet. Counters. Counters to be eye bars with sleeve nut adjustment, Suspenders. Suspension Rods to have turned e}'e at upper end, and either turned eye for pin at lower end or upset end and nut and thread adjustnzeut at floor beam. Iron Floor Beams. Iron Floor Beams to be either solid rolled I beams or built beam made of angle bar and plate properly stiffened, as per straiu diagram. End Portals. Portal Struts to be made either of T bar or of angle iron latticed. Top Struts. Intermediate Top Struts to be made of solid rolled I beams, or of angle bars, or of two chavuel bars latticed, as specified ou strain sheet. Lateral Pods, Lateral Rods to have upset ends with nuts, or with eyes at ends and sleeve-nut adjustment. Rivets The pitch of the rivets (etcept in latticed members,) shall in no case etceed six inches, nor be less than three times the diameter of rivets. Rivet holes must be accurately pouched, and rivets when driven must com- pletely fill the holes. MATERIAL. All iron used iu the work to be wrought iron, to be tough, fibrous and of that quality best suited to the purpose for which it is used. tilt. 'T'ensile Strength of Iron 50,000 lbs. per sq. iu. " Compressive " 40,000 " " Shearing ;6,000 PAINTING. All iron work to he thoroughly cleaned and painted before leaving the shops and to have ._ '~`~_ ~.,_ ..............coat of paint, after erection. FLOOR. II~~ r " Floor 'oist Y ` ~. ._' ~_~ ...._ lumber ..-._...~ Z,,_ _,. inches dee and ......_,: ~--a ~ p, .......inches thick, spaced about.-- ...... part. Floor Plank to be ......' `..I......... . '' "' Yv -.~-L.........lumber-_...-...,'~..~~..-_mchesthickand_____L___ to...../..Z,......inches wide, laid---.-_~.-d.....~•~,,~~,..~z Sidev~alk joist ... _ _ _ . _. _.__ _. Side~~alk floor...-...- ...................................Hub plank......................~..x..~..V...~.~ .. .......... ------ iI ~~ ... .. Wheel Guards _.._2 ~~ -" CONSTRUCTION. The entire work to be constructed im a thorough and workmanlike manner, and the details of construction to be of such character as to insure the greatest strength and durability to the bridge. s+; /g t