Depending on the clear cover, given the age of the structure I would test for carbonation with phenolphthalein indicator solution on a ‘fresh’ fractured concrete piece.
The tendons were bonded (grouted) tendons using HENNIGSDORF prestressing steel (oval-shaped tensioned wires) that have a history of stress corrosion cracking (SCC).
Voids in the grout (to bonded tendons) is still a problem today unless specially formulated grout and vacuum-assisted grouting...
I have done it many times, especially for 12 x 1/2"Φ strand multi-strand tendons. It is important to use a spacer plate at the onion fixed-end to ensure that the "onions" do not overlap, and you need to design the local and general zones reinforcement similar to other end zones.
VSL Technical...
Tensile forces exceeded the tensile strength of the concrete! You need to give a lot more info!
Hire an engineer! Give him/her copy of the original structural drawings and other relevant information. Have him/her conduct a site review.
Prof Thomas Murray passed last week at age 84.
I attended several of his AISC "virtual" seminars. Always a very professional researcher and presenter.
I am guessing several "Hokies" enjoyed his engineering classes and lectures.
A memorial is here: Modern Steel Link
Correct. Back in the day when there were mainly three international PT companies working on buildings: BBR (Structural Systems), FREYSSINET (Austress/PSC) and VSL. I am not sure if any of these 3 do PT to buildings in AU any more. Legacy lost, IMO.
BacBac:
For a CJ that is part of a 'pour joint' we usually have the width of the joint to be about 4 feet (1200 mm) - or more - so you can accommodate slab edge stressing and avoid pan stressing.
I have not practiced in AU for many years, but back in the day we used coupled CJ anchors all the...
There may be some regional difference on what is a ‘construction joint’.
My definition of a CJ is a temporary joint usually used at the convenience of the contractor as opposed to a permanent joint defined by the engineer of record on the structural drawings.
It would be very unusual to have...
It is a temporary partial-depth blockout/recess consisting of a (typically) plastic form pan to enable internal stressing without a full-depth slab penetration. Commonly used in BONDED PT slab systems. A curved stressing nose if often required to angle the stressing jack to clear the angled slab...
This coupler looks vey similar to a prestressing wedge chuck, as you stated.
With a wedge chuck there is a take-up load that needs to be applied to engage and displace the wedges (4 pieces in this case) so they are correctly seated to take the intended TENSION load. In prestressing strand...
I have to load test (in the field) some old (40+ years old) high-tensile post-tensioning components to a force not to exceed 33 kips (about 150 kN).
The post-tensioning element is made up of 7-wires to form a 1/2" nominal diameter strand, of 270 ksi tensile capacity. Outer six-wires are...
At the plank ends of pretensioned hollow core planks the strand is not developed, so whilst the plank is prestressed, it is not at its ends where shear is at its maximum.
But the hollow core appear to be running parallel with the exposed reinforcement.
Hollow core panels are typically ONLY reinforced in the long direction (span direction), with no transverse rebar.
Probably about 95% of FRP using in concrete related structural strengthening applications are unidirectional carbon layups. Most use wet layups, and a minority use pultruded strips.
In my experience - dates back to 1998 with FRP's - for such structures, FEM software is not commonly used. Most...
