Civil Engineering Reference
In-Depth Information
According to ( 2.37a ), the bending stress in the wires of the different wire layers
is
d
0 : 9980 2 sin 2 a 0
0 : 99953 r 0i
sin 2 a 0
r 0i
2 E ¼ 0 : 00354 0 : 2419 2
1 : 25
2
r bi ¼
196,000
r 0i
r bi ¼ 25 : 4
r 0i
:
According to ( 2.38a ), the torsion stress is
1 : 25
2
0 : 23430
0 : 99953 r 0i
0 : 23473
r 0i
76,000 ¼ 15 : 2
r 0i
s i ¼
:
Then with r 01 = 1.3 mm, r 02 = 2.55 mm, r 03 = 3.8 mm, the bending stresses
are
r b1 ¼ 19 : 4 N/mm 2 ;
r b2 ¼ 9 : 9 N/mm 2 ;
r b3 ¼ 6 : 7 N/mm 2
and the torsion stresses are
s 1 ¼ 11 : 7 N/mm 2 ;
s 2 ¼ 6 : 0 N/mm 2 ;
s 3 ¼ 4 : 0 N/mm 2 :
As shown in the example, the additional wire stresses in spiral ropes are not
very large.
2.1.6 Additional Wire Stresses in Straight Stranded Ropes
The wires of straight stranded wire ropes under tensile force are loaded like the
wires in spiral ropes by bending and torsion stresses. Besides that, they are loaded
with a second tensile stress caused by friction between the wires in the bent
strands, Schmidt ( 1965 ). The additional stresses will be evaluated using the space
curves of the strands and the wires.
According to ( 2.32 ), the equations for the space curve of the strand axis in a
straight stranded rope are
x S ¼ r S sin u S
y S ¼ r S cos u S
z S ¼
ð 2 : 39 Þ
r S
tan b u S
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