Civil Engineering Reference
In-Depth Information
A
X
B
10 kN
R
A,H
10 kN
x
(a)
A
X
N
AB
R
A,H
10 kN
x
(b)
10 kN
10 kN
ve
F
IGURE
3.8
Normal
force diagram for
the beam of Ex. 3.1
A
B
(c)
which gives
N
AB
=+
10 kN
N
AB
is positive and therefore acts in the assumed positive direction; the normal force
diagram for the complete beam is then as shown in Fig. 3.8(c).
When the equilibrium of a portion of a structure is considered as in Fig. 3.8(b) we are
using what is termed a
free body diagram.
E
XAMPLE
3.2
Draw a normal force diagram for the beamABC shown in Fig. 3.9(a).
A
X
1
B
10 kN
X
2
C
R
A,H
10 kN
A
X
1
R
A,H
10 kN
N
AB
x
L
/2
L
/2
x
(a)
(b)
A
B
10 kN
X
2
10 kN
10 kN
R
A,H
10 kN
F
IGURE
3.9
Normal force
diagram for the
beam of Ex. 3.2
N
BC
ve
A
B
C
(c)
(d)
