Wire Ropes Under Bending and Tensile Stresses - Wire Ropes: Tension, Endurance, Reliability - page 282

car moves between the ground floor and one or two floors above. The number of
trips up to the rope being discarded has to be calculated for this rope piece. The
ratio between the number of trips Z G that start or end on the ground floor and the
total number of trips Z, Holeschak ( 1987 ), has been evaluated by regression cal-
culation from his records. He found the ratio Z G /Z for different types of elevators
and this is shown in Fig. 3.82 . The ground floor factor is

f GF ¼ Z G

Z ¼ n F

with

n F number of upper floors
a = -0.114 for residential building
a = -0.282 for office building
a = -0.370 for freight elevator

The total number of trips is

Z ¼ Z G = f GF :

As bending length the rope route during the car acceleration should be taken but
at least the rope route for a trip between the ground floor and the next upper floor.

1.0
0.9
0.8

residential
building

0.7

office
building

0.6

0.5

freight
elevator

0.4

0.3

0.2

12 14 16 18 20 1 2 3 4 5 6 7 8 9 10

number of upper floors

Fig. 3.82 Ratio of the number of trips Z G /Z in elevators, Holeschak ( 1987 )