Simplified Design for Two-Way Slabs - Simplified Design of Reinforced Concrete Buildings - page 130

Column
C L

Column
C L

24'-0"

5'-0" 5'-0"

Slab edge 5'-0" 5'-0"

Column C L

14-#4T 13-#4T*

13-#4T*

14-#4B 14-#4B 14-#4B

14-#4B

Column C L

15-#5T 14-#4 15-#5T

10-#4B 14-#4B

10-#4B

Column strip Middle strip Column strip

*See special bar layout detail in Fig. 4-19

Figure 4-22 Bar Layout—Space Bars Uniformly within Each Column Strip and Middle Strip

From Table 4-9, for 9 in. slab with 12 12 in. column:

A c = 399.1 in. 2
J/c = 2523 in.3

From Fig. 4-17, with b 1 /b 2 = 15.88/19.75 = 0.8, γ v 0.38

v u = V u /A c + γ v M c/J
= (57,200/399.1) + (0.38 0.3 260.6 12,000/2523)

= 143.3 + 139.4 = 284.6 psi >>

φ4 f c ʹ

= 190 psi*

* b o /d = [(2 x 15.88) + 19.75]/ 7.75 = 6.7; from Fig. 4-13 with β c = 1, φ V c /b o d = 190 psi