3.5 Special Types of Trusses 65
C
A B
Hinged chain Hanger
a
C
A B
Hinged chain
b
A B
C
c
Hinged chain
Fig. 3.22 Trusses with hinged chain
The typical truss with a hinged chain located above the truss is shown in Fig.3.23.
Assume that the parameters of the structure are as follows:dD 3 m,hD 2 m,fD
7 m, andLD 24 m. We need to construct the influence lines for the reactions and
the internal forces in hanger,Vn. As usual we start with the kinematical analysis of
the structure: it shows that the structure is geometrically unchangeable and statically
determinate.
Joint n Sn
Sn–1
Vn
x
y
(tang − tana)^2 fd
Inf. line Vn
+
IL(RA)
f
−^4 d
Inf. line H
4 d
f^2 d= 0.857
f
Left portion −
(Right portion)
Connecting line
8
9 ′
9
RB
P= 1
A^3
4
5 7
RA 2 6 1
C
1
h
d
f
n
k
L=24m
a (^1) B
T
D
2
2
Vn
m
SleftSright
N
a
a
g
g
b
Fig. 3.23 Truss with a hinged chain: design diagram and influence lines