BUILDING LAWS 363 



case shall the slab portion exceed twenty times the thickness 

 of the slab. 



"All reinforced -concrete T beams must be reinforced 

 against the shearing stress along the place of junction of the 

 rib and the flange, using stirrups throughout the length of 

 the beam. When reinforced-concrete girders carry rein- 

 forced-concrete beams, the portion of the floor slab acting 

 as flange to the girder must be reinforced with bars near the 

 top, at right angles to the girder, to enable it to transmit local 

 loads directly to the girder and not through the beams, thus 

 avoiding an integration of compressive stresses due to 

 simultaneous action as floor slab and girder flange. 



"In the execution of the work in the field, work must be so 

 carried on that the ribs of all girders and beams shall be 

 monolithic with the floor slabs. 



"In all reinforced -concrete, structures special care must be 

 taken with the design of joints to provide against local stresses 

 and secondary stresses due to the continuity of the structures. 



"Shrinkage and thermal stresses shall be provided for by 

 the introduction of steel. 



"In the determination of bending moments due to the 

 external forces, beams and girders shall be considered as 

 simply supported at the ends, no allowance being made for 

 continuous construction over supports. Floor slabs, when 

 constructed continuously, and when provided with rein- 

 forcement at top of slab over the supports, may be treated 

 as continuous beams, the bending moment for uniformly 



distributed loads being taken at not less than . In th 



case of square floor slabs, that are reinforced in both direc- 

 tions and supported as continuous beams on all four sides, 



WL 

 the bending moment may be taken at . In floor slabs in 



juxtaposition to the walls of the building, which are acting 

 as simple beams, the bending moment shall be considered 

 WL 



as when reinforced in one direction. If the floor slab 



8 



is square and reinforced in both directions, but acting as a 



