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In my opinion that tolerance is for vertical positioning only (profiling). Post
Tension Institute (PTI) recommneds horizontal tolerance of tendon placement. Please
refer to the attached sheet.
Refer also to TR 43 (other sheet).
[file=../../e107_files/public/1187422863_7_FT38_tr43_tolerance.pdf]1187422863_7_FT38_tr43_tolerance.pdf[/file]
Hello there Mr. Yaser,
Thank you so much for the explanation.
Keep online from time to time because we need your technical expertise in this forum.
cheers.
-john mark-
The reason behind why we are keeping 3 levels of support to PT slab is to transmit the loads from the one under construction to a level where the accumulated capacity of the casted PT slabs resists the total loads from above.
Please refer to the attached sheets to better understand the effect of the construction/actual loads to the levels resisting the above loads.
If the correct propping is not being adhered, the consequence might be:
1. Collapse of the newly casted PT slab
2. Propagation of cracks in the bottom surface of the PT slab below the newly casted one.
3. Inducing more deflections in the PT slab below the newly casted one.
[file=../../e107_files/public/1186981986_7_FT34_back-propping_details.pdf]1186981986_7_FT34_back-propping_details.pdf[/file]
[file=../../e107_files/public/1186981986_7_FT34_back-propping_load_distribution.pdf]1186981986_7_FT34_back-propping_load_distribution.pdf[/file]
Basing from experience, the best way to stress a double live-end anchoragewhere the other side is a pan box anchorage is to do initial stressing at the pan box end, then on final stressing stage complete 100% stressing at the edge slab end.Then do the “pick-up” at the pan box end.This process may minimize the friction losses at the pan box end.
Thanks for the answer/insight.
We did the same process in our previous project. Only, we drilled at high point locations and did grouting at the holes. A very tedious procedure.
cheers.