n a loaded beam or s Jab both vc1 liwl and hori1. ontal shear are prcsent..lrul the net result of the 1wo fo~ is cctlled beam shear. !1\ era-ck resulting from these forces can occur near the support and exte;xls upward and oul\. \'3. «l at ~c of awro:iumately to the top. These forces are also p~1l m an elevated slab. _p1rt,cu a y around t Le perimele1 o W. t)t)Ortmg Cl)lumn~ and the combined result is called punching shear, as shown in Fig,. 6-5 --Punching Shear Beam Sh&ar Fig. 6-5 Shear Tension in rcinfoteed concrete can be caused by bending or shear, by dry­ ing shrinkage after the OOll CCete hardens, and by temperature changes. An exrunple of hooding tension is shown in Fig. 6-6. As "' beam i loaded, "'1· sion cracks will likely appear ai lhe bottom of the beam. They will develop rapidly in an unreinforced concrete beam with the each appearing near mid~ spon. Unreinforced concrete is weak in tension and will fail suddenly without warnuig shortly after the fust crack appears. LOocl$ ------------Ten11on Cracks Beam deflects under load Fl_g. ~ lension in a Boam Steel pnwides reinfon:emcot 10 lheconcrete where iensle forces exist lhat the coo­ en.-tc cannot resisl. The following discussion will ill USlrate the location in OOIICltlc mcmbcr1 where reinforcing steel can be most eflbctivdy u,;ed to resist tension. Ploct,g Roinforc:a,g Bara-100, E<ilion 6-,3 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 41 42 43 6-9