Civil Engineering Reference
In-Depth Information
Figure 3.2
Doubly reinforced and flanged sections in continuous beams
Figure 3.3(a) shows a doubly reinforced rectangular section of height
h
and width
b
.The
tensile rebar area
A
s
is located at a distance
d
from the bottom surface, and the compression
rebar area
A
s
at a distance
d
from the top surface. The effective depth
d
is equal to
h
d
.
−
ε
s
, respectively,
as shown in Figure 3.3 (b). The neutral axis is assumed to be located at a distance
kd
from
the top surface. The stresses in the tensile and compressive rebars are denoted as
f
s
and
f
s
,
respectively, in Figure 3.3(c).
The transformed area for tensile rebar is indicated by
nA
s
in Figure 3.3(d). The transformed
area for compression rebar is
mA
s
The strains in the tensile and compressive rebars are designated
ε
s
and
1)
A
s
. The subtraction of an area of compression
rebar
A
s
in the expression
mA
s
is to compensate for the same area included in the concrete
area
b
(
kd
). This is strictly for convenience in the calculation.
=
(
n
−
Figure 3.3
Cracked rectangular sections (Doubly reinforced)
