Civil Engineering Reference
In-Depth Information
Computing
2
and
m
1
12
I
s
for 24- ft- wide slab
(12
24)(7)
3
8232 in.
4
I
b
18,060 in.
4
2
(
E
)(18,060)
(
E
)(8232)
2.19
m
1
2
2.63
2.19
2
2.41
2
Determining Slab Thickness as per ACI Section 9.5.3.3
m
2.41
2
Use ACI Equation 9- 13
f
y
200,000
n
0.8
h
36
9
n
long
24
1
23 ft
n
short
20
1
19 ft
23
19
1.21
60,000
200,000
(23)
0.8
h
0.540 ft
6.47 in.
36
(9)(1.21)
Use 7- in. slab
16.7
LIMITATIONS OF DIRECT DESIGN METHOD
For the moment coefficients determined by the direct design method to be applicable, the
Code (13.6.1) says that the following limitations must be met, unless a theoretical analysis
shows that the strength furnished after the appropriate capacity reduction or
factors are
applied is sufficient to support the anticipated loads and provided that all serviceability
conditions such as deflection limitations are met:
1.
There must be at least three continuous spans in each direction.
2.
The panels must be rectangular, with the length of the longer side of any panel not
being more than 2.0 times the length of its shorter side lengths being measured c
to c of supports.
3.
Span lengths of successive spans in each direction may not differ in length by
more than one-third of the longer span.
4.
Columns may not be offset by more than 10% of the span length in the direction
of the offset from either axis between center lines of successive columns.
