Civil Engineering Reference
In-Depth Information
1000 N m
1500 N m
A
B
C
D
2m
1m
1m
F
IGURE
P.11.3
P.11.4
A bar ABCD has a circular cross section of 75mm diameter over half its length
and 50mmdiameter over the remaining half of its length. A torque of 1 kNm is applied
at Cmidway between B and D as shown in Fig. P.11.4. Sketch the distribution of torque
along the length of the bar and calculate the maximum shear stress and the maximum
angle of twist in the bar
G
70 000N/mm
2
.
=
23
.
2 N/mm
2
in CD, 0.38
◦
at C.
Ans.
τ
max
=
50 mm
diameter
1kNm
A
B
D
75 mm
diameter
C
1.0 m
0.5 m
0.5 m
F
IGURE
P.11.4
P.11.5
A thin-walled rectangular section box girder carries a uniformly distributed
torque loading of 1 kNm/mm over the outer half of its length as shown in Fig. P.11.5.
Calculate the maximum shear stress in the walls of the box girder and also the dis-
tribution of angle of twist along its length; illustrate your answer with a sketch. Take
G
70 000N/mm
2
.
Ans.
133.3N/mm
2
.InAB,
θ
=
=
10
−
6
x
rad.
3
.
81
×
10
−
9
(4000
x
x
2
/
2)
In BC,
θ
=
1
.
905
×
−
−
0
.
00381 rad.
10 mm
A
15 mm
B
15 mm
0.75 m
x
C
10 mm
2m
1m
2m
F
IGURE
P.11.5
