74 



resting on top of the beam tension bar. The purpose of 

 these ribs is to stiffen the beams laterally, and in case 

 of heavy concentrated loading to distribute the stresses 

 resulting therefrom over beams adjacent to the load. The 

 size of the tension bar will depend upon the number of 

 beams desired to act as a unit, the stiffening rib being 

 treated as a beam loaded at the points of intersection 

 with the floor beams. 



The stress in a beam supported at one end is four times 

 the stress in a beam of same span and loading supported 

 at both ends. Hence the formula for cantilever beams 

 uniformly loaded* is 



btress- 



where P equals projection, in inches. 



The tension bar is placed in the top of the beam and 

 the portion below the bar must contain at least 16 sq. in. 

 of concrete for each ton stress. 



Stirrups or U-bars placed as indicated by Fig. 1, Plate 

 III, provide resistance to shearing stresses. 



In addition to those in the beams at each intersection 

 of beams and stiffening ribs place a U-bar of the same 

 size as those in the beams. Also where a beam or girder 

 is supported by a plrder, place a T T -b:ir at the intersection 

 passing under the tension bars of the supporting girder. 



Instead of U-bars a continuous coil as shown by Fig. 2, 

 may be used. All bends for U-bars and coils should be 

 made with the longest possible radius to avoid weakening 

 the metal. 



Another form of reinforcement against shear is shown 

 by Fig. 3 consisting of a number (in this case 4) of small 

 tension bars in place of one large one, the ends of which 

 are bent up, as shown, at varying distances from the 

 point of support. In placing, the bars should be held 

 apart by means of small separators sufficiently to allow 

 the mortar to work well in between them. 



Any desired combination of the above forms may be 

 used." 



RETAINING WALLS. 



The following excerpt is made from the booklet of the 

 Concrete Steel Retaining Wall Co. on the Bone System of 

 retaining wall construction: 



"It is easy to design a reinforced concrete wall of the 

 same stability of any example of solid wall that may be 

 selected. The heel can be made of sufficient length, so , 



