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Structure engineer

 
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Kumar Praveen
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Joined: 10 Jun 2018
Posts: 6

PostPosted: Thu Jun 14, 2018 5:25 pm    Post subject: Structure engineer Reply with quote

Dear sefian,
i need to make cut out in slab of size 450*600mm for passing AHU pipe line. Problem is that slab is casted to 130mm in thickness and  there is not any provision of cut out while casting/planning. Can i make cut out in slab and what will be the Precaution to insure At site .
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Dr. N. Subramanian
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Joined: 21 Feb 2008
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Location: Gaithersburg, MD, U.S.A.

PostPosted: Fri Jun 15, 2018 3:38 pm    Post subject: Re: Structure engineer Reply with quote

Dear Er Kumar,

This is a practical problem and requires expertise and more details. If this is a new slab, additional reinforcements are necessary around the opening as shown in Fig. 10.53 (Example 10.10) of my RC design book (Oxford Univ. Press, 2013).

But you are going to cut an existing slab. It may be necessary to strengthen the slab around openings.

The most used method for increasing the moment capacity is to addsteel or FRPComposites plates to the surface of a slab, connected with the help of bolts or post-installedanchors. Although the installation of the steel plates is rather easy ithas to be considered that it must not interfere with the flooring system. Whenusing bolts for connecting the plates, they interfere with the flooring system.Normally the plates are installed on the bottom of the slab with post-installedanchors. A disadvantage of this method is that overlapping is difficult, thus itworks best when strengthening is required in only one direction.  See Example 5.6 of my RC design book for the calculations involved.

Anyway please also check whether strengthening is required. You have not informed the type of slab(one way, two way or flat slab), size of slab, where the cut out is made(near supports, mid span etc).

Best wishes
NS


Kumar Praveen wrote:
Dear sefian,
i need to make cut out in slab of size 450*600mm for passing AHU pipe line. Problem is that slab is casted to 130mm in thickness and  there is not any provision of cut out while casting/planning. Can i make cut out in slab and what will be the Precaution to insure At site .
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sktrisal
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Joined: 05 Apr 2016
Posts: 8

PostPosted: Fri Jun 15, 2018 4:30 pm    Post subject: Structure engineer Reply with quote

location of the cutout shall determine the strengthening proceduressktrisal


On Fri, 15 Jun 2018, 12:01 Dr. N. Subramanian, <forum@sefindia.org (forum@sefindia.org)> wrote:

Quote:
           Dear Er Kumar,

This is a practical problem and requires expertise and more details. If this is a new slab, additional reinforcements are necessary around the opening as shown in Fig. 10.53 (Example 10.10) of my RC design book (Oxford Univ. Press, 2013).

But you are going to cut an existing slab. It may be necessary to strengthen the slab around openings.

The most used method for increasing the moment capacity is to addsteel or FRPComposites plates to the surface of a slab, connected with the help of bolts or post-installedanchors. Although the installation of the steel plates is rather easy ithas to be considered that it must not interfere with the flooring system. Whenusing bolts for connecting the plates, they interfere with the flooring system.Normally the plates are installed on the bottom of the slab with post-installedanchors. A disadvantage of this method is that overlapping is difficult, thus itworks best when strengthening is required in only one direction. See Example 5.6 of my RC design book for the calculations involved.

Anyway please also check whether strengthening is required. You have not informed the type of slab(one way, two way or flat slab), size of slab, where the cut out is made(near supports, mid span etc).

Best wishes
NS


      Kumar Praveen wrote:                Dear sefian,
i need to make cut out in slab of size 450*600mm for passing AHU pipe line. Problem is that slab is casted to 130mm in thickness and there is not any provision of cut out while casting/planning. Can i make cut out in slab and what will be the Precaution to insure At site .     
     



     


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Naveen CHIPPAGIRI
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Joined: 14 Feb 2016
Posts: 1

PostPosted: Fri Jun 15, 2018 6:30 pm    Post subject: Structure engineer Reply with quote

Respected sir Im intrested in doing job in construction 
Would u please refer me to ur known companies thankq sir 


On Jun 15, 2018 9:31 PM, "Dr. N. Subramanian" <forum@sefindia.org (forum@sefindia.org)> wrote:
Quote:
           Dear Er Kumar,

This is a practical problem and requires expertise and more details. If this is a new slab, additional reinforcements are necessary around the opening as shown in Fig. 10.53 (Example 10.10) of my RC design book (Oxford Univ. Press, 2013).

But you are going to cut an existing slab. It may be necessary to strengthen the slab around openings.

The most used method for increasing the moment capacity is to addsteel or FRPComposites plates to the surface of a slab, connected with the help of bolts or post-installedanchors. Although the installation of the steel plates is rather easy ithas to be considered that it must not interfere with the flooring system. Whenusing bolts for connecting the plates, they interfere with the flooring system.Normally the plates are installed on the bottom of the slab with post-installedanchors. A disadvantage of this method is that overlapping is difficult, thus itworks best when strengthening is required in only one direction. See Example 5.6 of my RC design book for the calculations involved.

Anyway please also check whether strengthening is required. You have not informed the type of slab(one way, two way or flat slab), size of slab, where the cut out is made(near supports, mid span etc).

Best wishes
NS


      Kumar Praveen wrote:                Dear sefian,
i need to make cut out in slab of size 450*600mm for passing AHU pipe line. Problem is that slab is casted to 130mm in thickness and there is not any provision of cut out while casting/planning. Can i make cut out in slab and what will be the Precaution to insure At site .     
     



     


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deepesh songara
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Joined: 03 Mar 2018
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PostPosted: Fri Jun 15, 2018 8:30 pm    Post subject: Structure engineer Reply with quote

Hello sir , may i ask questions ?

Regards,
Deepesh Songara
Civil EngineerMobile: +918826882840Email: deepesh.songara04@gmail.com (deepesh.songara04@gmail.com)




















On Fri, Jun 15, 2018 at 9:08 PM, Dr. N. Subramanian <forum@sefindia.org (forum@sefindia.org)> wrote:
Quote:
           Dear Er Kumar,

This is a practical problem and requires expertise and more details. If this is a new slab, additional reinforcements are necessary around the opening as shown in Fig. 10.53 (Example 10.10) of my RC design book (Oxford Univ. Press, 2013).

But you are going to cut an existing slab. It may be necessary to strengthen the slab around openings.

The most used method for increasing the moment capacity is to addsteel or FRPComposites plates to the surface of a slab, connected with the help of bolts or post-installedanchors. Although the installation of the steel plates is rather easy ithas to be considered that it must not interfere with the flooring system. Whenusing bolts for connecting the plates, they interfere with the flooring system.Normally the plates are installed on the bottom of the slab with post-installedanchors. A disadvantage of this method is that overlapping is difficult, thus itworks best when strengthening is required in only one direction. See Example 5.6 of my RC design book for the calculations involved.

Anyway please also check whether strengthening is required. You have not informed the type of slab(one way, two way or flat slab), size of slab, where the cut out is made(near supports, mid span etc).

Best wishes
NS


      Kumar Praveen wrote:                Dear sefian,
i need to make cut out in slab of size 450*600mm for passing AHU pipe line. Problem is that slab is casted to 130mm in thickness and there is not any provision of cut out while casting/planning. Can i make cut out in slab and what will be the Precaution to insure At site .     
     



     


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Kumar Praveen
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Joined: 10 Jun 2018
Posts: 6

PostPosted: Sat Jun 16, 2018 8:50 am    Post subject: Repected N.S sir. Reply with quote

Repected N.S sir.
Sir i seen the diagrame you suggested , i feel  this diagram is useful  before casting of slab.  But my problem is that, slab is casted at site. After casting of few days HVAC  consultant suggested the place of AHU and duct for services.
Following information regarding slab 1. Slab is two way slab
2. Some Duct are coming near to end and some are far from end
3. Some of Duct are coming nearer to each other
4. diagram and place are located in attached file
plz see.
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Kumar Praveen
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Joined: 10 Jun 2018
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PostPosted: Sat Jun 16, 2018 9:50 am    Post subject: dear sir, Reply with quote

i attached a file showing location of duct


slab 001.jpg
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slab cut out
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slab 001.jpg


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sankar
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Joined: 26 Jan 2003
Posts: 26

PostPosted: Mon Jun 18, 2018 12:30 pm    Post subject: Structure engineer Reply with quote

Dear Dr. NS,
For two-way strengthening requirement, use of Carbon Fiber sheet may be thought of by providing it in two directions under the slab by the sides of opening.
Fixing of carbon fiber in place is easy with epoxy based adhesive. Only, UV resistant coat may have to be applied on carbon fiber if exposed to sunlight.
Your views, please.

Regards
Sankar Chakraborty


--Original Message--
From: Dr. N. Subramanian [mailto:forum@sefindia.org]
Sent: Friday, June 15, 2018 9:08 PM
To: general@sefindia.org
Subject: [SEFI] Re: Structure engineer

Dear Er Kumar,

This is a practical problem and requires expertise and more details. If this is a new slab, additional reinforcements are necessary around the opening as shown in Fig. 10.53 (Example 10.10) of my RC design book (Oxford Univ. Press, 2013).

But you are going to cut an existing slab. It may be necessary to strengthen the slab around openings.

The most used method for increasing the moment capacity is to addsteel or FRPComposites plates to the surface of a slab, connected with the help of bolts or post-installedanchors. Although the installation of the steel plates is rather easy ithas to be considered that it must not interfere with the flooring system. Whenusing bolts for connecting the plates, they interfere with the flooring system.Normally the plates are installed on the bottom of the slab with post-installedanchors. A disadvantage of this method is that overlapping is difficult, thus itworks best when strengthening is required in only one direction.  See Example 5.6 of my RC design book for the calculations involved.

Anyway please also check whether strengthening is required. You have not informed the type of slab(one way, two way or flat slab), size of slab, where the cut out is made(near supports, mid span etc).

Best wishes
NS



Kumar Praveen wrote:
Quote:
Dear sefian,
i need to make cut out in slab of size 450*600mm for passing AHU pipe line. Problem is that slab is casted to 130mm in thickness and  there is not any provision of cut out while casting/planning. Can i make cut out in slab and what will be the Precaution to insure At site .







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