114 REINFORCED CONCRETE CONSTRUCTION 



If necessary to prevent side bending (not a rigid condition, since a beam is 

 not similar to a column in all respects) 



(12) (40) 



= or or 6 = or > 19 in. 



In the best shaped beam b lies between 



1/2 d and 3/4 d. 

 Assume 6 = 18 in. 



lo 



( Or <j = 27.3 in., say 27 1/2 in. 



12,000 



,- =24 Ib. per square inch. 



' bd (18) (27.5) 



Web reinforcement is not theoretically needed and we will take 6 = 18 in. 

 and d = 27 1/2 in. Area of cross-section, 6d=(18)(27.5) =495 sq. in. 



a = (495) (0.0077) =3.81 sq. in. 

 We shall select four 1 1/8-in. round rods = 3. 98 sq. in. (See following table.) 



Round rods 



Square rods 



The spacing adopted is shown in Fig. 53. 

 V 12,000 



The maximum 

 : 35 Ib. per square inch. 



2ojd (4) (3.534) (7/8) (27.5) 

 Hooks will be provided at the ends of the rods for additional safety. Spac- 

 ing of bars is greater than necessary. Depth of concrete below the rods is 

 practically 2 in. 



12,000(2) 

 Minimum distance from the end of beam to edge of support is , , ~ = 



