Prestressing force in strand
Prestressing force in strand
(OP)
Hello People, i have a question i would like to ask, at this point it may sound stupid, but i don't want to make any mistakes. OK, so, a guy came in to my college to stress my beams (for my final year project), and the stress that he put in was 535, that's what he said, without given the units, and as per usual i forgot to ask him. The gauge that he used i will attach below, so can anyone just confirm how do i convert that into tensile strength of the strand ? or the breaking load ? Thank you very much.






RE: Prestressing force in strand
And student questions are not allowed on this site! Read the rules.
RE: Prestressing force in strand
If you knew the gauge pressure at max stress, and the jack ram area you could multiply pressure X area to get an approximate value for force. Looks like the stressing equipment is PJM from Australia.
RE: Prestressing force in strand
PJM Industrial manufacture two sizes of monostrand jacks/rams. One is 25t and the other is 30t capacity, with different effective ram areas, as follows:
If it was the 25t capacity ram that was used, your approx jacking force would be as follows:
Pj= 53.5 MPa * 3,388.6 mm2 = 181 kN
I am going to assume this is NOT 12.7mm 7-wire strand and probably 15.2mm diameter 7-wire strand, with a Ppu of 256 kN, so Pj= 70% Ppu.
Needs verification. Lots of 'ifs'.
RE: Prestressing force in strand
RE: Prestressing force in strand
RE: Prestressing force in strand
Thanks.
RE: Prestressing force in strand
Edvinas:
Not correct, unless you have cut off the stressing tails or grouted the tendon? If NOT, you can re-stress them.
If this was a real project, the PT company would be required to obtain a valid calibration certificate (or get the equipment re-calibrated) and possibly re-stress the tendons.
From previous posts, this is part of a research project you are doing with relatively short beams and checking losses. Did your elongations check out okay, based upon the beam and stressing configuration?
RE: Prestressing force in strand
RE: Prestressing force in strand