I am a Professional Engineer and a firefighter in N.Y. City. I have n
I am a Professional Engineer and a firefighter in N.Y. City. I have n
(OP)
I am a Professional Engineer and a firefighter in N.Y. City. I have no direct experience in post-tensioned construction, and would like to obtain the following information:
1. In a non-bonded post-tensioned slab or beam, is it possible to cut through a tendon without life safety issues to the cutter or anyone else nearby?
2. How often is this technique used in modern construction (part. in the northeast), and how often has it been used in the past?
3. Are there any external indicators in an existing structure as to whether it contains post-tensioned construction members?
Thank you for your consideration in this matter.
Yours truly, John P. Flynn, P.E., Pruho@aol.com
1. In a non-bonded post-tensioned slab or beam, is it possible to cut through a tendon without life safety issues to the cutter or anyone else nearby?
2. How often is this technique used in modern construction (part. in the northeast), and how often has it been used in the past?
3. Are there any external indicators in an existing structure as to whether it contains post-tensioned construction members?
Thank you for your consideration in this matter.
Yours truly, John P. Flynn, P.E., Pruho@aol.com





RE: I am a Professional Engineer and a firefighter in N.Y. City. I have n
RE: I am a Professional Engineer and a firefighter in N.Y. City. I have n
1. In general, it is possible to cut through an unbonded tendon without life safety issues. Cutting through tendons and tendon breakage occur commonly during construction. Typically, concrete spalling will occur or the anchorage will pop out of the side of the slab or beam a few inches. However, explosive concrete ruptures can occur which may injure anyone close by. Slabs that are renovated, such as those that have openings added for elevators, require tendons to be cut and reanchored. Refer to the Post-tensioning Institute's publication, "Controlled Demolition of an Unbonded Post-Tensioned Concrete Slab" for more info. Their number is 602-870-7540.
2. Post-tensioning has been in use since 1957.
3. The easiest way to tell whether a slab or beam is post-tensioned is to look at the slab edge or beam edge for the grouted anchorage pockets.
4. In flat slabs and flat plates, the tendons are layed out in what are termed the banded and uniform directions. In the banded the direction, which is typically the long dimension of the structure, the tendons are grouped along the column lines. In the direction perpendicular to this, the tendons are located uniformly in the slab at a 2' to 3' spacing. This should at least give you an idea where the tendons will be located.
RE: I am a Professional Engineer and a firefighter in N.Y. City. I have n
Jim Seaman P.E.
RE: I am a Professional Engineer and a firefighter in N.Y. City. I have n
I advice never touch them . WHY?
Because, when slab system prepered the scarfolding system is under the slabs and they carry the floor. When executive engineer tested the concrete and say it is ready to carry itself, post-tension engineers start to pull tendons untill the concrete leave from scarfolding and carry itself.After this operation you can remove the bottom molds. JUST think the power in the tendons and never touch it pls.
RE: I am a Professional Engineer and a firefighter in N.Y. City. I have n
RE: I am a Professional Engineer and a firefighter in N.Y. City. I have n
Will the anchorage region (the new one)'explode' because of the dynamic effect of re-anchoring ?
Is there any detailed documentation on this ? on the web, PCI, etc ...
Thank you !
Ramez.
RE: I am a Professional Engineer and a firefighter in N.Y. City. I have n
RE: I am a Professional Engineer and a firefighter in N.Y. City. I have n
Post-tensioning manual 5th ed
by PTI,
the Post Tensioning Institute,
where the more important aspects of the practice are given, construction advice included.
RE: I am a Professional Engineer and a firefighter in N.Y. City. I have n
RE: I am a Professional Engineer and a firefighter in N.Y. City. I have n
Short answer is "yes". 1 foot is a little short for perimeter stressing, but you can do internal stressing - little more difficult and a few more $ but it can be done.
On multistory building, at the contractor's request, we often detail stressing such that NONE is at the perimeter to avoid personnel and equipment on exterior scaffolding.
You could also consider, alterantive dead and live ends, and the live ends could be recessed from the slab perimeter by 3 feet, and the last 3 feet gets conventionally reinforced. The dead ends can go as close to the slab perimeter as end concrete cover permits.
HTH
RE: I am a Professional Engineer and a firefighter in N.Y. City. I have n