Civil Engineering Reference
In-Depth Information
Table 2.13 Range of diameter related force 2 S
a
/d
2
of open spiral ropes for certain numbers of
load cycles N
1
, at which with a certainty of 95 % at most 1 % of the ropes are broken
Rope
diameter
d (mm)
Range of diameter related force 2S
a1
=
d
2
in N/mm
2
Number
of wires
z
for load cycles N
1
N
1
= 20,000
50,000
125,000
320,000
800,000
2,000,000
10,000,000
10
37
402
318
251
198
156
124
98
12.5
37
385
304
241
189
150
118
94
16
61
386
305
241
190
150
119
94
20
61
369
292
231
182
144
114
90
25
85
366
290
229
180
142
113
89
32
85
349
276
218
172
136
107
85
40
100
340
269
213
167
132
105
83
50
125
333
264
209
164
130
103
81
63
160
327
259
205
161
127
101
80
80
200
320
253
200
157
124
98
78
100
250
313
248
196
154
122
97
76
125
292
305
241
191
150
119
94
74
Lower tensile force S
lower
= 0; rope length L = 100 m; terminations: resin socket
Rope tensiele stress r
z
¼
1
:
70 S
=
d
2
2.7.2.2 Force Range
As has been repeatedly pointed out, the range of specific force should be calculated
in such a way that with a certainty of 95 % at most 1 % of the ropes is broken for a
required endurance. If the required number of load cycles (full load cycles) is
smaller than 2 9 10
6
, the allowed specific force range can be calculated directly
with (
2.111
) and the constants in Table
2.11
.
If the required number of load cycles is bigger than 2 9 10
6
, first the specific
force range 2S
aDc
/d
2
has to be calculated with (
2.111
) for N
c
= 2 9 10
6
. Then for
the required number of load cycles bigger than 2 9 10
6
, according to the inverted
(
2.104
) the range of the specific force is
1
=
2a
1
þ
1
ð
Þ
N
c
N
D
2S
ac
=
d
2
¼ 2S
aDc
=
d
2
:
ð
2
:
114
Þ
For both (
2.111
) and (
2.114
) the constants have to be taken from Table
2.11
.
A survey of the range of specific forces 2S
a1
/d
2
is presented in Table
2.13
, with
which open spiral ropes with resin sockets can reach a given number of load cycles
N
1
. These numbers N
1
mean the number of full load cycles at which with a
certainty of 95 % at most 1 % of the wire ropes are broken. The lower specific
force is S
lower
/d
2
= 0. With increasing rope diameters d, an increased number of
wires z in the wire rope have been inserted as is usual in practice. The rope length
is L = 100 m.
As Table
2.13
shows, the allowed range of specific force is strongly reduced
with an increasing rope diameter. For the smallest rope diameter d = 10 mm and
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