Civil Engineering Reference
In-Depth Information
10.4.2.3
The column section
Figure 10.10
refers to an uncracked section
where, of course,
x/h
1. Referring to the concrete stress block in Figure
10.10c, the concrete compressive force is
‡
(10.7a)
It is seen from Figure 10.10b that
x
cu
/
e
cu
=
x
/
e
c
=
x
Ó/
e
Ó
c
; using these relations it
is easy to show that Eqn 10.7a can be written as
(10.7b)
Including the contribution by
n
layers of steel, the total compressive force is
(10.8)
and the resistance moment about the mid-depth of the section is
(10.9)
where (Figures 10.10c and
10.9
a)
(10.10)
Introduce the dimensionless parameter
(10.11)
and the dimensionless parameters a and ¦ (see Eqn 10.3). Then divide Eqns
10.7Î10.9 by
f
cu
bh
to obtain:
(10.12)
(10.13)
(10.14)
where
and
k
2
is defined in Eqn 10.10.
