Civil Engineering Reference
In-Depth Information
20 kN
10 kN
5 kN
C
D
E
4m
A
B
F
4 5m
F
IGURE
P.20.10
P.20.11
The truss shown in Fig. P.20.11 carries a train of loads consisting of, left to
right, 40, 70, 70 and 60 kN spaced at 2, 3 and 3m, respectively. If the self-weight of the
truss is 15 kN/m, calculate the maximum force in each of the members CG, HD and
FE.
Ans.
CG
=
763 kN, HD
=−
724 kN, FE
=−
307 kN.
F
H
D
A
B
1.5 m
E
C
G
8
2m
F
IGURE
P.20.11
P.20.12
One of the main girders of a bridge is the truss shown in Fig. P.20.12. Loads
are transmitted to the truss through cross beams attached at the lower panel points.
The self-weight of the truss is 30 kN/m and it carries a live load of intensity 15 kN/m
and of length greater than the span. Draw influence lines for the force in each of the
members CE and DE and determine their maximum values.
Ans.
CE
=+
37
.
3 kN,
−
65
.
3 kN, DE
=+
961
.
2 kN.
G
C
H
4m
3.5 m
3m
A
B
D
E
6
4m
F
IGURE
P.20.12
P.20.13
The Pratt truss shown in Fig. P.20.13 has a self-weight of 1
.
2 kN/mand carries a
uniformly distributed live load longer than the span of intensity 2
.
8 kN/m, both being
applied at the upper chord joints. If the diagonal members are designed to resist
tension only, determine which panels require counterbracing.
