# jul06

The catenary sag  for the main cables was measured in mar06. The table below shows
• The cable name
• The date and time when each of the catenaries were measured.
• The total tiedown tension at each measurement (averaged 5 minutes around the time supplied by felipe).
• The az posiition (dome side), dome position, and carriage house position for each measurement.
 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 azimuth position versus hour during the measurements
• The gregorian dome za during the measurements. The ch was left at a constant za for each measurement day.
• The position (linear pull down) of the tiedown jacks during the measurements.
• The tension (from summing the two cables at each tiedown) at each triangle corner during the measurements.
• Color coded dashed vertical lines were placed at the times when each cable was measured.

• The bottom two plots use  black (td12), red (td4), and green (td8) to distinguish the positions and tensions for the 3 tiedowns.
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
` home_~phil`