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Cut outs in beams for services
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vijaydshah
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PostPosted: Sat Dec 01, 2012 4:31 am    Post subject: Cut outs in beams for services Reply with quote

Hellow dear sefians

It is nice to be in this discussions. Thanks to everybody for partcipating. One more small but important question is  what should be the preferable mode fro taking out  the services from beam ? Will Providing cut outs away from confining zone be a solution ? Our sp does not speak anything about strengthening cut out by providing ms plate all around. Also it covers the limitation of sizes and location under gravity loading only. Sp says not to allow any cut outs in potential plastic zone . How can one arrive the location as for every floor it will be different As the stiffness goes on changing every floor.

Can any one throw light on this topic also ? If discussions on structural advantages and disadvantages of providing cut outs in the beams are done it will be also very helpfull for all of us.


Over to all participants.
Thanks

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vdshah
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Manoharbs_eq
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PostPosted: Sat Dec 01, 2012 5:04 am    Post subject: Reply with quote

Dear sir,


we usually adopt steel (MS) sleeve for beams and flat slabs. we generally don't prefer cutout.

However when inevitable the cutout is placed at compression zone and where stress are less. with additional reinforcement based on stress.


Rgds
Manohar
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gautam chattopadhyay
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PostPosted: Sat Dec 01, 2012 5:10 am    Post subject: Cut outs in beams for services Reply with quote

Our codes are meant for ordinary buildings only. cut out in slabs and beams we encounter in industrial buildings. However, we should not always depend on provisions of codes for everything, we should impose our own judgement to the conditions not found in codes. A cut out should always be reinforced around. Most theoretically speaking, since free edge is not subjected to moment and shear force there will be redistribution of stresses around a cutout. hence a local analysis should be performed before deciding on reinforcements.

On Sat, Dec 1, 2012 at 10:01 AM, vijaydshah <forum@sefindia.org (forum@sefindia.org)> wrote:
Quote:
           Hellow dear sefians

It is nice to be in this discussions. Thanks to everybody for partcipating. One more small but important question is what should be the preferable mode fro taking out the services from beam ? Will Providing cut outs away from confining zone be a solution ? Our sp does not speak anything about strengthening cut out by providing ms plate all around. Also it covers the limitation of sizes and location under gravity loading only. Sp says not to allow any cut outs in potential plastic zone . How can one arrive the location as for every floor it will be different As the stiffness goes on changing every floor.

Can any one throw light on this topic also ? If discussions on structural advantages and disadvantages of providing cut outs in the beams are done it will be also very helpfull for all of us.


Over to all participants.
Thanks
     


vdshah
     



     


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Manoharbs_eq
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PostPosted: Sat Dec 01, 2012 5:49 am    Post subject: Reply with quote

Dear Gautam sir,
I completely agree, quite satisfying answer.

Rgds
Manohar
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muralimithun
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PostPosted: Sat Dec 01, 2012 9:15 am    Post subject: Reply with quote

hi, all,

I just want to add, for free edge, moment will be zero, but shear will not be zero. Hence design for shear to be carried out.

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Murali
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Ashutosh Pathak
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PostPosted: Sat Dec 01, 2012 9:58 am    Post subject: Cut outs in beams for services Reply with quote

Dear Sefians
Most constructions are dominated by Architects and other stake holders
with scant engineering appreciation. The cut outs for many of our
constructions are hence provided arbitrarily.
Unfortunately many of our Engineering Heads too have inadequate
engineering appreciation and their decisions at site (?) are either
too conservative or otherwise.  Projects are invariably time
constrained and lack of adequate technical literature on the subject
compound the woes.
This is an important grey area which needs inputs from our experts.


On 12/1/12, vijaydshah <forum@sefindia.org> wrote:
Quote:
Hellow dear sefians

It is nice to be in this discussions. Thanks to everybody for partcipating.
One more small but important question is  what should be the preferable mode
fro taking out  the services from beam ? Will Providing cut outs away from
confining zone be a solution ? Our sp does not speak anything about
strengthening cut out by providing ms plate all around. Also it covers the
limitation of sizes and location under gravity loading only. Sp says not to
allow any cut outs in potential plastic zone . How can one arrive the
location as for every floor it will be different As the stiffness goes on
changing every floor.

Can any one throw light on this topic also ? If discussions on structural
advantages and disadvantages of providing cut outs in the beams are done it
will be also very helpfull for all of us.


Over to all participants.
Thanks


vdshah









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srijith
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PostPosted: Sat Dec 01, 2012 10:58 am    Post subject: Cut outs in beams for services Reply with quote

Dear sefians,
I do agree with the fact that most of the constructions are dominated by architects who are least bothered of structural implications.
Can anyone explain, if its recomended to provide drainage or any other service line (Rainwater pipe, lightining arrester, AC line to ODU, or Electrical lines) through the columns.
Srijith
Civil Engineer,
Muscat On Dec 1, 2012 2:01 PM, "pathak.ashutoshpathak" <forum@sefindia.org (forum@sefindia.org)> wrote:[quote]            Dear Sefians
Most constructions are dominated by Architects and other stake holders
with scant engineering appreciation. The cut outs for many of our
constructions are hence provided arbitrarily.
Unfortunately many of our Engineering Heads too have inadequate
engineering appreciation and their decisions at site (?) are either
too conservative or otherwise. Projects are invariably time
constrained and lack of adequate technical literature on the subject
compound the woes.
This is an important grey area which needs inputs from our experts.


On 12/1/12, vijaydshah wrote:
      --auto removed--

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knsheth123
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PostPosted: Sat Dec 01, 2012 2:07 pm    Post subject: Beam Opening Reply with quote

Dear Sefians

The Opening in beams can be analysed using FEM as plane stress model then converting the stress to internal forces as is done when a shear wall is modelled as plane stress element.

Detailed closed form analysis and design is present in the Book for Practicing Engineers :

" Concrete Beam with Opening : Analysis and Design
   By M. A. Mansur and KiangHwee Tan
   CRC Press
  removed due to copy right issue. Please be careful to ensure copy righed books not uploaded.

SEFI blessed us to bring Dr. N. Subramanian Sir as  Resource Person.
He has served as Ready Reckoner for References on almost all topic.
His posts are encouraging and informative.

Grateful to SEFI,  NS Sir and others like , Shri Rangrajan Shri Ravi .........

K. N. Sheth
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thirumalaichettiar
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PostPosted: Sat Dec 01, 2012 2:52 pm    Post subject: Reply with quote

Er.K. N. Sheth,
Please check whether the book is copy righted one or not? I doubt it is a copy righted one which is not allowed in the forum. Check the forum instructions laid in the begining.
Also check the contents or other pages where it should have mentioned that neither the book or part of it can not be published without the written permission.

I find the phrase of words on page 6 as per attachment.

If so kindly delete immediately.

T.RangaRajan.



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Dr. N. Subramanian
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PostPosted: Sat Dec 01, 2012 3:20 pm    Post subject: Re: Beam Opening Reply with quote

Dear Prof. Sheth,

As mentioned by you the book by Prof. Mansur and Tan of the National University of Singapore is the only(and the best) book on Beams with Openings. I also wanted to suggest that book only. As Er Rangarajanji has rightly pointed out the posting of this book here violates the copyrights of CRC Press and may result in unwanted legal proceedings. hence please remove it from here. This book is a result of numerous beams with openings tested by Prof. Mansur and his co-workers.

My usual thumb rule, which may be correct most of the time is to provide the rods intercepted by the opening in beam or slab at the sides of the opening. It is also necessary to provide additional rebars at the corners as shown in the enclosed Fig. Hidden beams will also help in the case of slabs. If the slab opening is large, say more than 25 % of the area, it is better to provide beams around the openings.

On behalf of Er Rangarajanji also, I Thank you very much for your kind words. Such encouragements from Professors like you motivate us.

Warm Regards,
Subramanian
knsheth123 wrote:
Dear Sefians

The Opening in beams can be analysed using FEM as plane stress model then converting the stress to internal forces as is done when a shear wall is modelled as plane stress element.

Detailed closed form analysis and design is present in the Book for Practicing Engineers :

" Concrete Beam with Opening : Analysis and Design
   By M. A. Mansur and KiangHwee Tan
   CRC Press

SEFI blessed us to bring Dr. N. Subramanian Sir as  Resource Person.
He has served as Ready Reckoner for References on almost all topic.
His posts are encouraging and informative.

Grateful to SEFI,  NS Sir and others like , Shri Rangrajan Shri Ravi .........

K. N. Sheth



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