REINFORCED CONCRETE 85 



355. Special Reinforcement : 



{a) Rectangular slabs reinforced for strength in one direction 

 only shall be reinforced in the other direction, to prevent 

 shrinkage cracks, by rods not less than f in. in diameter, 

 placed above the main reinforcement and spaced not 

 more than 2 ft. c. to c. 



{/;) Similar slabs, designed for concentrated loads, shall be 

 reinforced perpendicular to the main reinforcement 

 by rods -| in. in diameter, spaced not more than 1 ft. 

 c. to c., to distribute such loading. 



{c) Slabs, beams, or girders having construction joints (Par. 

 362) shall be provided with shearing rods proportioned 

 to transmit shear due to any partial loading. The 

 diameter of such shall not be less than -| in., the length 

 shall not be less than 96 diameters, the spacing shall not 

 exceed 2 ft. c. to c., and they shall be placed near the top. 



(d) Reinforcement against leakage cracks, when water- 

 proofing (Par. 360), shall be distributed evenly over 

 the entire affected area and shall consist of rods not 

 less than f- in. in diameter spaced not over 18 in. c. to c. 

 in two directions perpendicular to each other. 



(c) Reinforcement for temperature stresses (Par. 347) shall 

 be distributed over the entire area of the cross-section 

 in a ratio varying with the same. 



356. Splicing of Reinforcement. Wherever it is necessary 

 to splice the reinforcement the rods in tension shall be connected 

 by a direct splice of a strength equal to that of the rod, or by 

 overlapping their ends. The length of lap in diameters shall not 

 be less than the total stress in the rod, at point of splice, divided 

 by 300. In compression, where reinforcing rods over 1 in. in 

 diameter are joined, they shall be butted and fully spliced; rods 

 of smaller diameter may be lapped as in tension. 



No splices shall be made at points of maximum stress. 



357. Minimum Reinforcement. The minimum reinforce- 

 ment in slabs, beams or girders shall not be less than three- 

 fourths of 1 per cent (J%) of the effective area of the concrete; 

 in columns with longitudinal reinforcement only not less than 

 2 per cent and in columns having circumferential reinforcement 

 such reinforcement shall not be less than 1 per cent of the effect- 

 ive area. 



