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RE: Un-bonded P-T in bridges

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The clarification is as follows :
Always regarding what just I have known, I am not refering to the main
stays,
in cable-stayed bridges, but the cables reinforcing the deck. But we are
talking
of box type bridges ( poutres-caissons ), usually with a combination of two
families of cables, a set of prestressed cables within the concrete
( usually straight and running through the slabs concrete ) and a set of
cables
external to the webs but inside the box. These last ones, are unbonded and
with
grease injection. An example of this arrangement, is found in the ' Pont de
La Fléche'.
I'm sorry if I dissapointed you with this outcome !
Regards,
Raúl Labbé

-----Mensaje original-----
De: Mark Geoghegan <structuraltech.vsl(--nospam--at)verizon.net>
Para: Seaint <seaint(--nospam--at)seaint.org>
Fecha: Jueves, 06 de Diciembre de 2001 08:20 p.m.
Asunto: Re: Un-bonded P-T in bridges


>Dear Raul,
>
>Thank you for your reply.
>
>One clarification to your response:
>
>I am familiar with tendon/strand replacement and re-stressing for
>cable-stays, but is the European/French experience to have unbonded tendons
>within concrete beams, decks and girders too? I know that Michel Virlogeux
>has been involved with several external P-T bridges (and many suspension
and
>cable-stayed bridges too!) but i am mainly interested in P-T tendons WITHIN
>concrete flexural elements, and NOT external to these elements.
>
>If you have any additional info that you can share that would be
>appreciated.
>
>Regards,
>
>Mark Geoghegan
>
>
>
>
>
>>I'm not familiar with the american practice in this issue,
>>but, yes of course in the european bridges you can see
>>lots of applications with unbonded postensioned cables.
>>French bridges have been using this arrangement with
>>grease injection. The ease for replacement and retensioning
>>of these cables, is mentioned as a clear advantage of this
>>procedure.
>>
>>-----Mensaje original-----
>>De: Mark Geoghegan <structuraltech.vsl(--nospam--at)verizon.net>
>>Para: Seaint <seaint(--nospam--at)seaint.org>
>>Fecha: Jueves, 06 de Diciembre de 2001 12:37 p.m.
>>Asunto: Un-bonded P-T in bridges
>>
>>
>>>Dear SEAINT forum:
>>>
>>>I am familiar with the use of un-bonded post-tensioning in building
>>>structure throughout North America, but I am not aware of any new bridge
>>>projects in the USA today that use UN-bonded P-T in bridge decks - please
>>>correct me if I am wrong.
>>>
>>>If this is true, why?
>>>
>>>Does the AASHTO/DOT code/s prohibit its use?
>>>
>>>I am familiar with unbonded P-T tendons failures due to corrosion in say
>>pre-1980's buildings (and a few bonded tendon failures on bridges too),
but
>>i am curious about unbonded PT in bridges.
>>
>>Historically, has unbonded P-T been used in bridge decks in the USA or
>other
>>parts of the world, and if so, does anyone have any project references?
>>
>>By UN-bonded P-T, I do NOT mean to include EXTERNAL P-T, rather ONLY
>>greased-and-sheathed strand systems within concrete decks/elements etc.
>>
>>Thanks in advance.
>>
>>Mark Geoghegan
>
>
>
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