Talk:Prestressed concrete

message: This article on prestressed concrete has much more depth than the post-stressed article, and both are about almost identical procceses.
Enelson 23:12, 30 April 2006 (UTC)
thread_title: Merging

message: Q. I donkkt quite follow the description of the post-tensioned processes, especially unbonded.  At what point to the tendons engage the cured concrete?  Could someone please provide some diagrams, photos or a good link for this?
:A. The tendons do not engage the concrete, they are unbonded from the concrete, hence the name.
:a. That is true. Also the tendons pull the concrete shape from the ends where the tension is applied by jacks. the shape may be forced into a camber from the tensioning. Bond with the tendons is un-necesary.  —Preceding unsigned comment added by 170.63.96.108 (talk) 18:03, 6 December 2007 (UTC)
thread_title:  post-tensioned concrete  

message: Here is an excellent diagram:
 and I can convert it to english, if someone can translate it for me! --Knulclunk 03:56, 16 July 2007 (UTC)
replies: text: But what does it mean?  A good description to go with it might be good. Jason A. Recliner (talk) 07:51, 2 December 2008 (UTC)

text: (belated reply) To tension them (SA). In this manner (LA) the cables are Post-tensioned., other wise they are pretensioned. I beleive it helps make the profile of the tendons easier (parabolic)in construction to give it the right capacities for a unique construction. Other wise your dealing with different tendon configurations such as harped etc. This should (and other elevant information with sourcing of course) be added to the article if someones up for describing the differences better. Ottawa4ever (talk) 12:42, 17 September 2010 (UTC)
thread_title:  Diagrams 

message: I deleted a line that claimed prestressed concrete was invented by Freyssinet, which was in contradiction to Wikipedia's own Freyssinet page.
The Portland Cement Association claims "prestressed concrete was patented by a San Francisco engineer in 1886." http://www.cement.org/basics/concreteproducts_prestressed.asp 
A brief history on prestressed concrete would improve this page.  —Preceding unsigned comment added by 210.18.214.5 (talk) 05:20, 17 May 2008 (UTC)
replies: text: Freyssinet did not invent prestressing he did howver make it more mainstream and was the fiorst to apply it to a structure. The steel was created back in the 1880s as PCA mentions, but was not used in structures because high strength steel was no pratical at that point. Any of this information is common knowledge in any prestressed text book. Ottawa4ever (talk) 17:08, 24 July 2009 (UTC)
thread_title:  History 

message: As a non-expert reading this article, it sounds like the "grout and forget" procedure is unreliable and it should not be assumed the system is working. Probably should actually take a look that it is working, though the grouting around the cable likely makes this impossible.
Would it be possible to leave post-tensioned cabled ungrouted, so that at a later time they can be removed, inspected, and reinstalled, or just replaced with a new post-stress cable assembly?
I realize that releasing cable tension weakens the structure, though with two or more overlapping / crosscrossing cable layers, that would provide overall tensioned support while a single cable/bundle is being removed for inspection. 
Could also build a tiny robot camera to pull through the cable hole and examine the concrete internally, plus also a traveling spray head to flush out corrosive chemicals, and to apply a sealing coat to cracks in the wall.
Probably could still leave a structure like a highway bridge in normal usage while a service shuttle travels along it, pulling cables out for inspection, doing hole inspection and cleaning, and reinstalling or replacing the post-tensioned cables. 
(This general design concept is hereby released to the world by me as prior art and now may not be patented by anyone if it isn't already, though specific device applications to carry it out can probably still be patented. -- Dale Mahalko, Gilman, WI, USA.)
-- DMahalko (talk) 02:14, 10 April 2016 (UTC)
thread_title:  Post-stress cable inspection and replacement? 

message: Bonded post-tensioned concrete is the descriptive term for a method of applying compression after pouring concrete and during the curing process (in situ). The concrete is cast around a plastic, steel or aluminium curved duct, to follow the area where otherwise tension would occur in the concrete element.
A set of tendons is fished through the duct and the concrete is poured. Once the concrete has hardened, the tendons are tensioned by hydraulic jacks that react (push) against the concrete member itself.
When the tendons have stretched sufficiently, according to the design specifications (see Hooke's law), they are wedged in position and maintain tension after the jacks are removed, transferring pressure to the concrete. The duct is then grouted to protect the tendons from corrosion.
This method is commonly used to create monolithic slabs for house construction in locations where expansive soils (sometimes called adobe clay) create problems for the typical perimeter foundation. All stresses from seasonal expansion and contraction of the underlying soil are taken into the entire tensioned slab, which supports the building without significant flexure.
Post-tensioning is also used in the construction of various bridges, both after concrete is cured after support by falsework and by the assembly of prefabricated sections, as in the segmental bridge.
Among the advantages of this system over unbonded post-tensioning are:
* Large reduction in traditional reinforcement requirements as tendons cannot destress in accidents.
* Tendons can be easily "woven" allowing a more efficient design approach.
* Higher ultimate strength due to bond generated between the strand and concrete.
* No long term issues with maintaining the integrity of the anchor/dead end
</blockquote>
: Unbonded (orig text), to be reworked in non-User Manual style (WP:NOTGUIDE), and pix reduced.
: Geekstreet (talk) 08:56, 24 August 2016 (UTC)
thread_title: Bonded post-tensioned concrete

message: The inclusion of text & image of stressed ribbon bridges within the Pre-tensioned section is incorrect. Most if not all examples of these built in the real world (ie not in labs) will have the ribbon tendons post-tensioned while the deck is temporarily supported. Some may use pre-tensioned planks as the deck elements, but the defining element of these bridges is the ribbon tendons. The reworded version takes these refs out, so they can be moved elsewhere in the article Geekstreet (talk) 07:37, 19 August 2016 (UTC)
thread_title:  Stressed ribbon bridges to move 

message: The original section titled "Unbonded post-tensioned concrete" (since renamed "Unbonded post-tensioning") contained many images & associated text describing details of various site operations. I feel this makes this section into a user manual in style, contrary to WP:NOTMANUAL.  I have reworked the text, adding additional material but removing all the text referencing the images as I think they stand OK without it if adequately captioned. I have also removed quite a few of these "site-sequence" images but kept those which identify the key items described in the section, and gave them extended captions.
If this is not considered an improvement pls revert & discuss. Geekstreet (talk) 10:08, 24 August 2016 (UTC)
thread_title:  Unbonded post-tensioning - removed content 

message: The following Wikimedia Commons file used on this page has been nominated for deletion:
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Participate in the deletion discussion at the nomination page. Community Tech bot (talk) 15:23, 4 July 2018 (UTC)
thread_title:  A Commons file used on this page has been nominated for deletion