118 REINFORCED CONCRETE CONSTRUCTION 



The distance from the support to the point where web reinforcement is 

 unnecessary is only 12 in. The rod can thus be bent up at the required 

 place between these two points. Fig. 55 shows the construction necessary 

 to locate the place where the rod should be bent. If the inclined rod received 

 a stress of 16,000, the length V should equal 50 diameters (from table) or 



Z' = (50)(l/2)=25 in. 

 but this rod receives only 



Q80 



"""" Ib. per square inch. 



and the length I' necessary is 



3920 



1/2=6 1/4 in. 



4y (4) (80) 

 In this case this length can easily be obtained. 



It should be clear from the sketch that, if a greater length than about 

 9 in. were required for V , some kind of anchorage at the end of rod should be 



Nut.-'' 

 and washer 



FIG. 55. 



provided. A possible method would be to use a large nut and washer on the 

 end of the rod, as shown. This would perhaps give sufficient bond but the 

 work of construction would be troublesome. A hook as shown at the end 

 of the horizontal bars is generally considered more satisfactory. 



Tests seem to indicate (Art. 39) that too much reliance should not be 

 placed upon one or two bent rods. For this reason, in the preceding prob- 

 lem it would be good design to use also the two stirrups as shown. 



Illustrative Problem. Design a beam to span 10 ft. and to support a load 

 of 4900 Ib. per foot (not including weight). We shall assume the weight of 

 beam at 400 Ib. per foot. 

 p = 0.0077 

 A; = 0.378 

 i = 0.874 



