Simplified Design for Two-Way Slabs - Simplified Design of Reinforced Concrete Buildings - page 113

a − h ≤ 4h

y 2

y 2

(2)

(1)

b x 1 x 1

Spandrel beam (ACI 13.2.4) Use larger value of C computed from (1) or (2)

Values of torsion constant, C = (1 - 0.63 x/y)(x 3 y/3)

x*

y 4

202
245
288
330
373
416
458
522
586
650
714
842
970
1,098
1,226

5
369
452
535
619
702
785
869
994
1,119
1,244
1,369
1,619
1,869
2,119
2,369

6
592
736
880
1,024
1,168
1,312
1,456
1,672
1,888
2,104
2,320
2,752
3,184
3,616
4,048

7
868
1,096
1,325
1,554
1,782
2,011
2,240
2,583
2,926
3,269
3,612
4,298
4,984
5,670
6,356

8
1,188
1,529
1,871
2,212
2,553
2,895
3,236
3,748
4,260
4,772
5,284
6,308
7,332
8,356
9,380

9
1,538
2,024
2,510
2,996
3,482
3,968
4,454
5,183
5,912
6,641
7,370
8,828
10,286
11,744
13,202

10
1,900
2,567
3,233
3,900
4,567
5,233
5,900
6,900
7,900
8,900
9,900
11,900
13,900
15,900
17,900

12
2,557
3,709
4,861
6,013
7,165
8,317
9,469
11,197
12,925
14,653
16,381
19,837
23,293
26,749
30,205

14
—
4,738
6,567
8,397
10,226
12,055
13,885
16,629
19,373
22,117
24,861
30,349
35,837
41,325
46,813

16
—
—
8,083
10,813
13,544
16,275
19,005
23,101
27,197
31,293
35,389
43,581
51,773
59,965
68,157

12
14
16
18
20
22
24
27
30
33
36
42
48
54
60

*Small side of a rectangular cross section with dimensions x and y.

Figure 4-9 Design Aid for Computing Torsional Section Constant C