\_'§~~'--. c..,,, Fig. 137 Su,Qportin9 Top Bats in a Joist Some joists may be doubl and even iriplo tho strutdr<I joist width and hvc eitber double or triple the amounts of reinforcing bars or petbap S a smaller number ofla,ger sized bars. Because joist chair. ; :uc made to SUPt)()rt IWO rein­ forcing bars oc,ly, it may bo necessary IO place two or JJOS$ibly tht<e 5UCh chahs in line with each other actn5S the width of Che joist lo accommod te Ille proper number of bars. Di. s-l Til. mrlon jl)S lso u1. lletl conhnuou. " header J01~t.., or bridging ri~~ ex. tend c. ontinu OUS!Y lbt:: full Je Q"'g_ffior~ ar tight angle. '> l O the 1rn1t11 job:ts and are toe same deillh as thejoi~IS, Distn"'bution n"bs are used for the longer joist spans to brace the joists lotenlly. Thefe is no lilce<I rule to tbo number of rib< used, but the Engineer will generally u. se one at mid-span for spans between 18 and 24 feet, and two at the third points for longer spans. Reinforcing bars in these ribs are shown on the placing drawing., and usually coosist of one or perhaps h\'o lop and bortorn straight bars, lnp spliced as necessary. The bottom bridging bars will lay across the bottom joist bars and tile Wp bars are tied IO the temperature Sleet in the joist slab. tmperatu~ ttlnfort:~menr is placed a J\cc JO~~ !iolccvcs, and conduit S are installed anc inspec<ed. h may C-011S1st oi etther reinf Ol'-'ing bars or welded ~ «'. linforccmcnt. If reinforcing bars are use4, they a~ p Ltced o. n top of all 01hr bnrs, wllh suppon bars un<kn:. :ath them p~!le) 10 the J,Oisl ba. Tern.. pernture bars are spaced according to the placing drawi11gs. lap splioed into contin110us liocs and cxtcndcd into edge beams or walls and hooked only wh..-. ~-When small siz. od reinforcing ban are required. care in placing is neces­ sary IO mairuain straight bar lines. 1 H Concn,t,a Aelnro,c;ng St Nt tnstilutt Section 609 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 6-9