Pretension Load for Guy Wire Supported Flare Stack

[cdi12]

Any guidelines/formulas/references how to calculate pretension load for guy wire supported flare stack. Is it percentage of the cable breaking strength? Thank you very much.

 

[dik]

I've not done any 'big' stacks, but I've not pretensioned other than mildly snug... just adds to compressive loads in the whole length of the stack and these occur anyway in the event there is any movement...

Dik

 

[apsix]

Although not directly applicable for stacks TIA/EIA-222 'Structural Standards For Steel Antenna
Towers And Supporting Structures' states "Initial tension in the guys, for design purposes, is normally 10 percent of the published breaking strength of the strand with upper and lower limits of 15 and 8 percent respectively. Values of initial tension beyond these limits may be used provided consideration has been given to the sensitivity of the structure to variations in initial tension and, if necessary, to dynamic behavior (see note below). Consideration shall be given to the site ambient temperature range. In the absence of site specific data, the initial tensions shall be based upon an ambient temperature of 60°F." as found at

http://www.floridatowers.com/tia222f.htm

 

[dik]

thanks, apsix...

Dik

 

[warrenw]

cdi12
We use Galvanized Bridge Strand for the guy ropes on our Stacks which are pre-stretched by the manufacture to eliminate most of the construction stretch.
The initial pretension that we use is nominally 4.5% of the breaking strength with a minimum of 2.5% in the most unfavorable cold stack/hot ambient combination.
If you have a cold stack condition (stack shrinkage) and a hot ambient temperature (rope growth), the ropes will start to go slack and lose some of the pre-tension. In this condition we want to have a pre-tension of at least 2.5% of the breaking strength.

 

[SlideRuleEra]

See pages 36 and 37 in "USS Wire Rope Engineering Hand Book". You can download this document (zipped .pdf file) from this page of my website

http://www.slideruleera.net/miscellaneous.html

http://www.SlideRuleEra.net