100 REINFORCED CONCRETE CONSTRUCTION 



the beam, as shown in Fig. 48. In heavy construction the ends 

 of all bars should be bent into a hook. The most convenient 

 method of using reinforcement is to bend up two rods at a time 

 and make all the bars inclined at an angle of 45 degrees with the 

 horizontal. The bars bent should theoretically be such as to 

 keep the center of gravity of the beam cross-section in the line 

 drawn vertically through the center of the section. An excep- 

 tion occurs to the bending of two rods at a time, in the case of 

 an odd number of horizontal rods. Here, one of the bends may 

 consist of either one or three rods. 



If bent rods are not required to provide for diagonal tension, 

 then the horizontal rods may be dispensed with at the points, 



- No I bars ..No 2 bars .-No 3 bars ,-No 4 bars 



>^^/^_\___\ 



FIG. 48. 



beyond which they are not needed to provide for tension due to 

 bending. This method of stopping off the horizontal rods is not 

 desirable, however, as the bond in the concrete near the middle 

 of the beam is not as good as would be the case near the end 

 where the moments are smaller. Also, when a bar is discon- 

 tinued, the stress in those which remain is immediately increased 

 tending still further to impair the bond between the steel and the 

 concrete. This is true whether or not a hook is employed on the 

 discontinued rods. With bent up rods a more ideal condition 

 exists. The horizontal components of the upturned bars act 

 with the bars unbent in taking the tension due to bending, and 



