Why Is Jacking force for post-tension tendons the same?
Why Is Jacking force for post-tension tendons the same?
(OP)
I am asking this question because in the field I saw that the jacking is the same but elongation for each tendon, but doesn't each tendon needs it's own jacking force because in the design each tendon is subjected to different moment and load ?






RE: Why Is Jacking force for post-tension tendons the same?
I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.
RE: Why Is Jacking force for post-tension tendons the same?
Doug Jenkins
Interactive Design Services
http://newtonexcelbach.wordpress.com/
RE: Why Is Jacking force for post-tension tendons the same?
I am having a hard time to understand that in the field they were jacking tendons with the same force but the pulled length for each tendon is different (they measured the length of the tendon that was pulled for each tendon is different as specified by the plan) but my question is the following :
In designing the strands the slab is divided into strips, but each strip is subjected to different load and moment, so it is reasonable that each tendon need different stressing force and hence different jacking force, how come that in the field all the tendons are jacked the same force ?
RE: Why Is Jacking force for post-tension tendons the same?
RE: Why Is Jacking force for post-tension tendons the same?
But if spacing is the only criteria in this how come that each tendon is jacked with different length (pulled with different length but same jacking force) ? how we calculate the length of the wired that is pulled from the jacking ?
RE: Why Is Jacking force for post-tension tendons the same?
Dik
RE: Why Is Jacking force for post-tension tendons the same?
RE: Why Is Jacking force for post-tension tendons the same?
I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.
RE: Why Is Jacking force for post-tension tendons the same?
Dik
RE: Why Is Jacking force for post-tension tendons the same?
No, P varies along the length of the tendon, depending on the tendon profile and tendon type. Friction varies for different prestress systems.
The P used in the calculation above is the value at each point along the tendon, not the jacking force.