Main cable catenary measurements mar06

jul06

     The catenary sag  for the main cables was measured in mar06. The table below shows
Cable 
     Date 
     Time
total Kips From Td's
(by Measurement)
az pos
(dome side)
Dome pos
ch pos
M-8-1 
    3/17/06 
   2:19 p.m.
37
270
8.5
8.8
M-8-2 
     3/17/06
    2:43 p.m.
37
270
8.5
8.8
M-8-3
    3/17/06 
   2:59 p.m.
39
270
8.5
8.8
M-8-4 
    3/17/06 
   3:30 p.m.
79
270
8.5
8.8
M-8-North 
    3/17/06 
   4:02p.m.
84
270
9.0
8.8
M-8-South 
    3/17/06 
   1:40p.m.
34
265
8.5
8.8
 
 
 
 
     
M-4-1 
    3/18/06 
   11:29 a.m.
68
270
10
0
M-4-2 
    3/18/06 
   11:56 a.m.
62
270
10
0
M-4-3 
    3/18/06 
   12:24 a.m.
63
270
10
0
M-4-4 
    3/18/06 
   12:48 a.m.
57
270
10
0
M-4-North 
    3/18/06 
   10:48a.m.
79
270
10
0
M-4-South 
    3/18/06 
   1:18p.m.
62
270
10
0
 
 
 
 
     
M-12-1 
    3/23/06 
  11:42 a.m.
62
270
10
8.8
M-12-2 
    3/23/06 
  1:17 a.m.
62
270
10
8.8
M-12-3 
    3/23/06 
  1:35 a.m.
67
270
20
8.8
M-12-4 
    3/23/06 
  2:10 p.m.
67
270
10
8.8
M-12-West 
    3/23/06 
   11:06a.m.
67
270
10
8.8
M-12-East 
    3/23/06 
   2:34p.m.
70
270
10
8.8

Average tiedown tension: 61 kips (averaging over all cable measurements).

What was going on during the sag measurements:

    You can compute the tensions in a cable from the sag measurements. When doing this you need to know  the position of the azimuth, dome,  carriage house, and the tiedown tensions when the measurement was made.

    The tiedown tensions are recorded using load cells as the connecting pins for the tiedown jacks. There are two tiedown cables at each corner of the platform (the reported tensions are the sum of these two cables) . The load cells are read once a second and recorded on disc.

    Four plots were made for each measurement day. They included:

 The plots show the tiedown tensions and az, za positions  (.ps) (.pdf):

During the measurements some things were moved:
 
tower 8 
17mar06
dome za=8.5
ch  za=8.8
 

 

15:18
 

 

auto tracking of tiedowns with distomats turned on. 
Jacks moved by 8 inches
tensions at each corner increased by about 8 kips
Affected cable measurement M-8-4 and M-8-North
15:54 az moved 270-> 266
greg za moved 8.5->9 deg
affected cable measurement M-8-North
tower 4
18mar06
dome za=10
ch za=0 
Looks like the auto tracking of the tiedowns was left on. 
Jacks moved by about an inch during the measurements.
Tensions were higher than tower 8 (20 to 35 kips in the 3 cables).
tower 12
23mar06
domeza=10
ch za=8.8
 

 

13:42
 
 

 

Dome moved to za of 20 degrees
This affected cable measurement M-12-3
The tension in corner 12 only  changed by 1 or two kips since the az was perpendicular to tower 12.
Corner 8 lost all tension while corner 4 increased by 20 kips.
This motion may have caused the platform to slide horizontally a little toward tower 4.
14:00 Dome moved back to za=10.
The auto tracking of the tiedowns was left on. 
The jacks moved by about an inch during the measurements.

The carriage house was moved to za=0 for cable 4 measurements.
It was at za=8.8 for the other two cable measurements.

processing: x101/060317/tdcatenary.pro
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