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Subject: "Design of POT-PTFE bearings."     Previous Topic | Next Topic
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Jayant
Charter Member
1 posts		 Dec-13-05, 01:56 AM (PDT)
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"Design of POT-PTFE bearings."
 
   Hi all! I am bridge designer from India and i have a query as regard to design of superstructure in seismic zones IV and V of India. It could be realised that in POT/PTFE bearings design maximum horizontal force is restricted to 25% of design vertical load.(As per IRC:83 part-III).This restrictic imposes problem for all conventional PSC /RCC T-girder design upto 40m span in above zones.It is seen that with seismic co-efficient of .18 (for zone IV) and .27 (for zone V), the maximum transverse horizontal force (to be restricted by fixed and longitudinal guided PTFE bearings only ) imvariably comes more than 25% of design vertical load for simply supported bridges for span range upto 40m and with 3 or more girder system.
one solution is to adopt pinned and metallic guided bearing in place of fixed and long. guided PTFE bearings, but it would alter the load distribution in girders and heavy section for end cross beam.
Can anybody suggest an alternative arrangement or any case in which above sited provision (restriction of horizontal force) has been ignored.

Thanks
Jayant.


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Jsenior
Charter Member
 May-30-08, 02:10 PM (PDT)
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1. "RE: Design of POT-PTFE bearings."
In response to message #0
 
   I would suggest you look at using modified pot bearings. These bearings would offer uplift restraint as well as holding the bearing together in the event of an earthquake. We have designed uplift bearings for the UK market which I am sure with some tweaks could be used .

I trust this helps

Regards

John Senior


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erpartha
Charter Member
4 posts		 Jul-08-08, 01:25 PM (PDT)
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2. "RE: Design of POT-PTFE bearings."
In response to message #0
 
   I feel, use of pinned bearing is the most widely used alternative (In India)to take care of the same.


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ravindra88irse
Member since Mar-2-09
1 posts		 Mar-10-09, 09:15 AM (PDT)
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3. "RE: Design of POT-PTFE bearings."
In response to message #0
 
   RDSO, Min. of RLys. have published a guideline on design of Pot PTFE bearings. You may also refer it. Send me a mail at ravindra88irse@yahoo.com, if you need it.
RKGOEL


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