144 REINFORCED CONCRETE CONSTRUCTION 



The web and flange of a T-beam can be considered well tied 

 together when slab reinforcement crosses the beam and when the 

 web reinforcement extends well up into the slab. The bonding 

 should be especially well looked after near the end of beam, and 

 this is generally accomplished by means of the bent rods brought 

 up as high as possible, in addition to the slab reinforcement (as 

 mentioned) acting at right angles to the length of the beam. 

 Along the center of the beam the differential stresses between 

 the beam and slab are not large, but it is better to insert vertical 

 stirrups extending up into the slab at occasional intervals since 

 shrinkage of the concrete is apt to part the slab from the beam if 

 there is not some means to hold the two together mechanically. 

 The thinner the sections, the more thorough should be the 

 bonding. 



* f < 1 



f 



*HH C 



T 



Cross section 



Stress Diagram 



FIG. 73. 



When frames are not used for beams and girders, successful 

 results can be obtained by wiring the main rods together and 

 employing U-shaped stirrups with hook ends to act as hangers 

 by which to suspend the rods in the form. The length of the 

 hook should be sufficient to permit the stirrup to rest on the top 

 of the slab form. The hook has the further advantage of increas- 

 ing the bond between the beam and slab. 



With a T-beam it is necessary to distinguish two cases when 

 applying formulas for design; namely, (1) the neutral axis in 

 the flange, and (2) the neutral axis in the web. 



Case I. The Neutral Axis in the Flange. All formulas for 

 "moment calculations" of rectangular beams apply to this case. 

 It should be remembered, however, that b of the formulas de- 



