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Proposal of single row of piles in Semi integral bridges

 
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msazarudhin
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PostPosted: Tue Apr 20, 2021 3:50 pm    Post subject: Proposal of single row of piles in Semi integral bridges Reply with quote

Due to stability issues, we won't provide single row of piles in simply supported spans. But, in semi integral bridges is it all right to provide single row of piles at abutment location?


P.S: Semi integral bridge means there is an integrity at pier locations and bearings at abutment locations.
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vikram.jeet
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PostPosted: Wed Apr 21, 2021 2:43 am    Post subject: Reply with quote

Dear Er

As a general engineer ( not as bridge design expert) , I think Single row of piles arrangement seems weak in direction perpendicular to row line. Braking and temp forces in bridges are Longitudinal ones , and the pile row in Longitudinal direction takes care,it can even take care E pressure on abutment , but seismic forces with EQ in transverse direction will create heavy moments in piles and stability of bridge is dependent completely on moment capacity of piles , depth of fixity of piles etc. Wheel loads near to kerb also create transverse moments and to be borne by piles. Transverse/ diagonal wind also create moments in transverse dir.

Piles in at least two rows , is a safer arrangement.

Best wishes
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msazarudhin
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PostPosted: Thu Apr 22, 2021 3:56 am    Post subject: Reply with quote

Thanks Vikram for casting light on this topic. I agree with your point but the reply is generic and didn't address my specific question of proposing single row of piles in Semi-Integral abutment. Because in fully integral abutment single row of piles is preferred arrangement due to its inherent flexibility. I would like to hear from Bridge design experts please!
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pvgraju
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PostPosted: Mon Apr 26, 2021 6:46 am    Post subject: Proposal of single row of piles in Semi integral bridges Reply with quote

Dear Sir,

If single row of piles are proposed then pile will be subjected to large bending moments due to loads on bridge in transverse direction. But piles will be designed only for axial compression,tension,lateral loads. With two rows of piles Moment loads will be transferred as push and pull,piles will not be a cantilever in the transverse direction. This will add to stability also.A bridge may be integral or semi integral but load transfer will be same with some reduction.

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P.V.Gavarraju
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vikram.jeet
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PostPosted: Mon Apr 26, 2021 7:06 am    Post subject: Reply with quote

Dear Er PV Gavarraju,
Yes , I also expressed the same view. But Er msazarudhin view of providing flexibility  needs to be understood , since I did not dealt with integral bridges, though dealt with design of RCC &psc bridges.  Still not able to visualize the stability Vs flexibility . Request eminent sefi members dealing with such strs to enlighten us all on sefi.
Er azarudhin can throw some light on such strs , if he can spare time, and let know in brevity about need for flexibility , keeping stability of structure intact.
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msazarudhin
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PostPosted: Tue Apr 27, 2021 4:47 am    Post subject: Reply with quote

Dear Gavarraju,

Single row of piles means piles kept in parallel with substructure (Abutment) direction and so in this case too, piles are not cantilever in transverse direction whereas in longitudinal direction it is. Irrespective of the number of rows kept, piles will be subjected to bending moments and it can be reduced by increasing the number of piles. In addition to that, piles are designed for axial loads (compression/tension) and bending moments (resultant). Bending moment and shear force (pattern) diagram isn't same for an integral structure and a non-integral structure.
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pvgraju
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PostPosted: Wed Apr 28, 2021 10:04 am    Post subject: Proposal of single row of piles in Semi integral bridges Reply with quote

Dear Sir,

Piles will be designed for various loads and will be tested for confirmation of load carrying capacities. The formulas for pile design are only empirical and shall be confirmed by test. If you design pile for bending moment the same is to be tested in the field. But only axial capacity and lateral capacity will be checked.

So by placing piles away from CG -in two rows in transverse direction-abutment direction moment will be transferred by push and pull. In the longitudinal direction also load will be transferred by push and pull by this arrangement.

If you have any filed testing methodology to check moment carried by pile you can proceed. Other wise design to be done like above.

Regards,

P.V.Gavarraju
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msazarudhin
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PostPosted: Fri Apr 30, 2021 7:51 am    Post subject: Reply with quote

Er. Vikram,

"Single row of piles are commonly considered as the BEST foundation practice in integral bridges, in many countries, including USA, UK, Ireland. Single row of pile allows the abutment stem to translate into and out of the soil as it provides maximum ductility and flexibility in cyclic bending. Piles may be oriented with bending to occur about the strong or weak axis". This is a verbatim of IRC Integral bridges guidelines.

Er. Gavarraju,

It's not like that if I can't test moment capacity of pile at field, we shouldn't propose single row of piles.

Expecting replies from bridge engineers who worked in semi-integral bridges please!
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vikram.jeet
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PostPosted: Fri Apr 30, 2021 9:18 am    Post subject: Reply with quote

Thank you Er Gavarraju ji for throwing light on such structures .

Bridge engg is a specialised field , but semi-integral bridges are further.
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vikram.jeet
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PostPosted: Fri Apr 30, 2021 11:23 am    Post subject: Reply with quote

Thanks Er msazarudhin saheb,

Since you are dealing with these structures , surely be best judge of the intricacies of analysis &design of integral/ semi integral bridges.

Working in a specialised consultancy  dealing in such structures provides unique experience.

Best wishes
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