In continuous beams (those which ha YC more than two supports), the com­ pression in conetete is sometimes high in the bottom near a support. For this reason. and for the structural integrity requirements of the Building Code, some bottom n:inforcing bars arc extended and spliced with the bars in an adjoccnt span. REINFORCING BARS Reinforcing bats are available in different grades (see next chapter). Each grade has distinctive sirength properties. Then: arc parts of a structure where one grade may be used to bctcer advantaic than another. Therefore, the grades are identified on fhe struclwlll drawin~ Each grade rn,s wllat is known as specified yield strength and tensile strength. Yield strength is the load limit to which the steel will $!retch ond rerurn to its original length, much fbe same as stretching a rubber band. Tensile strength is the lod limit al which the steel breaks. WELDED WIRE REINFORCEMENT Welded wire reinforcemen t (plain or deformed) is made from wld-drawn wite. Shccls, rolls and ""i"" benl from shcc:IS an, spocirlcd in various yield sirengrhs. Welded wire reinforcement LS available in various widtl\., and lengths. CONCRETE PROTECT ION To protect reinforcement agaill St fire, corrosion or exposure to weather it m\l St have a mioimutn cover of oonc:retc. The minimum concrete oc,yu ls specified in building codes and shown on the structural drawings. The con­ crete cover is measured from the exttrior face of the concrm to lhe o UISide of the reinforcement. ln corrosive environments, such as chemical storage and manufacturing facilities. wutewfttcr treatment plants, st:rucrures exposed to seawater, bridges and parking struetures exposed to de. icing salts, additional concrete cover-may be required. This is usually specified on the structural d. rawinas. ln many instunccs, coated reinforcement is used as n corrosion­ pro1oction sysu,m for chose types of sttuciurcs. For more information on coated reinforcing steel, see Chapter 18. 6-10 Conc<Ole Reln Jorolng Sleel lnstih Ae 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