the specification of PT slab:
flat plate 9" slab (300' x 60'), 270 cables type mono strand, 1/2" dia 7-wire strand, E=28500 ksi, fpu= 41.3 kip. f jaking 70% fpu.
Length cable = 231' type banded type, the cable passed over eight columns).
The question is , in case damage in cable cause cut, how far it will goes out of edge slab, is there in equation shows that, the distance will be from slab edge measured.
Be noted based on EXPERIMENTAL OBSERVATIONS, this cable didn't went out so far, so, I need to know which equation give in inches?
The attached picture shows four banded groups, its first cable from the right.
The critical location for the cable is where you have the lowest losses.
In AASHTO, the final per-stressing force should not exceed (0.80 Fyp) to ensure the cable would not rupture
I do not understand the question properly, what does goes out of edge slab means?
Get out in which direction?
I think, for vertical direction (through the slab 9" thickness) it is controlled by the ducts meaning that it would not go anywhere.
In the longitudinal direction, it is controlled by friction between the cable and the grout and duct
I am talking about unbounded post-tension, no grout, in case been cut and no bond so the cable is free to move in opposite direction, VSL used to repair the cut cable.
http://www.vsl.net/service/repairs-and-modifications
thanks Ariadne, its general information, nothing talking about it, what I am concern is any equation give distance or elongation of cable been cut.
it is unbonded wire, so it should first de-jack the wire to un-stress the wire before you cut the wire. After un-stressed, you can cut any where you want. Don't cut any wires which are stressed.
Dear Wong, thanks for your answer, my be I made confuse in my question, so I made change in the question, now, what I want to ask:
post tension concrete slab made with unbound cables, due not expected action happened in one of the cable (like drill in slab and hit the cable or point corrosion ) cause cut the prestreesed cable, so, what will happened? it will went out in fast and force, like this failure you can see a small 7-wire strand jump out side slab edge.
This question is how far it will went out side slab edge, you may say 5" or 10" depend on profile of the cable, so I need to know the equation which consider all these parameters.
thanks a lot.
Dear Ehab, the broken wire that shoots out happens mostly.during stressing when the wire is not gribbed by the anchorage wedge. In your case, cut wire whether it move out or not depends on the gribbing friction and the movement of the wire that you are looking for. I never come acrosd with equation for it. But from the first principle, it may be calculate te energy stored as strain energy in the wire. This is the energy releasred from the cut wire and it drives the wire forward. The worse case is to assume the grib friction zero and.equates this strain energy to the work done by moving the broken wire a distance x, then solve for x. This is the upper limit. Hope this would help.
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