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Pointed discussions on tall buildings - Use of Flat Slab -co
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Econf_Moderator
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PostPosted: Tue Nov 20, 2012 9:12 am    Post subject: Pointed discussions on tall buildings - Use of Flat Slab -co Reply with quote

Dear All: 

Not all of us  design tall buildings. But  most likely, a lot of us will be designers or project engineers for tall buildings in years to come. And needless to say, almost all of us have opinions about how things ought or ought not to be done. 


We welcome comments from all engineers regarding issues they may want to comment on, on design and construction of tall buildings. If we look around us in Mumbai, NCR and most of the metros of Mumbai, majority of the new construction is tall buildings- and here I am using the IBC definition of 50 m. And almost everyone has done tall buildings, if I use the Chinese definition of 28m. 


To start the ball rolling, 


What is the general opinion of SEFIans to the use of flat slab with core shear wall system as a structural system for tall buildings? 
- Should it be allowed in Zone V? 
- Up to what max height? 
- What are the conditions one may impose for use of such a system for tall buildings? 


Look forward ot hearing form you all on this topic


best regards,


CVR Murty
Swaminathan Krishnan
Alpa Sheth 


Econference Moderators

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sarfaraj.husain
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Joined: 26 Jan 2003
Posts: 90

PostPosted: Tue Nov 20, 2012 10:33 am    Post subject: Pointed discussions on tall buildings - Use of Flat Slab -co Reply with quote

though steel buildings are not much encouraged in india........after which height it is better to go for steel building ???


sarfraj...




From: "Econf_Moderator" <forum@sefindia.org>
To: econf34289@sefindia.org,  
Date: 11/20/12 03:58 PM
Subject: [E-CONF] Pointed discussions on tall buildings - Use of Flat Slab -column with shear wall core as structural system



Dear All:

Not all of us design tall buildings. But most likely, a lot of us will be designers or project engineers for tall buildings in years to come. And needless to say, almost all of us have opinions about how things ought or ought not to be done.


We welcome comments from all engineers regarding issues they may want to comment on, on design and construction of tall buildings. If we look around us in Mumbai, NCR and most of the metros of Mumbai, majority of the new construction is tall buildings- and here I am using the IBC definition of 50 m. And almost everyone has done tall buildings, if I use the Chinese definition of 28m.


To start the ball rolling,


What is the general opinion of SEFIans to the use of flat slab with core shear wall system as a structural system for tall buildings?
- Should it be allowed in Zone V?
- Up to what max height?
- What are the conditions one may impose for use of such a system for tall buildings?


Look forward ot hearing form you all on this topic


best regards,


CVR Murty
Swaminathan Krishnan
Alpa Sheth


Econference Moderators





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ishacon
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Joined: 01 Apr 2008
Posts: 148

PostPosted: Tue Nov 20, 2012 11:10 am    Post subject: Pointed discussions on tall buildings - Use of Flat Slab -co Reply with quote

Dear All,

Let us first be clear about using flat slab or flat plates -
the latter seems to have caught the fancy of contractors from Mumbai.

1. If it is flat plate, I would be reluctant to advocate it
for Zone V unless we do not insist on Dual system as per IS 1893,
due to the higher shear at shear wall and plate junctions.
May consider it for buildings up to 50 M height ensuring performance criteria
for human comfort in terms of the lateral drift.
In any case Flat slab with drop panel would be always more desirable
from performance basis. To what height , will still be a question I am not sure.

2. Having said as above, it becomes imperative that provisons of IS 1893 need to be
streamlined to determine appropriateTime period for shear wall buildings

VP Agarwal
ISHA CONSULTANTS (P) LTD
NEW DELHI 110074

PH : 011-2630 1158 ;
08010071749 ; 093 1345 2180
Quote:
-- Original Message --
From: Econf_Moderator (forum@sefindia.org)
To: econf34289@sefindia.org (econf34289@sefindia.org)
Sent: Tuesday, November 20, 2012 4:00 PM
Subject: [E-CONF] Pointed discussions on tall buildings - Use of Flat Slab -column with shear wall core as structural system


Dear All:

Not all of us design tall buildings. But most likely, a lot of us will be designers or project engineers for tall buildings in years to come. And needless to say, almost all of us have opinions about how things ought or ought not to be done.


We welcome comments from all engineers regarding issues they may want to comment on, on design and construction of tall buildings. If we look around us in Mumbai, NCR and most of the metros of Mumbai, majority of the new construction is tall buildings- and here I am using the IBC definition of 50 m. And almost everyone has done tall buildings, if I use the Chinese definition of 28m.


To start the ball rolling,


What is the general opinion of SEFIans to the use of flat slab with core shear wall system as a structural system for tall buildings?
- Should it be allowed in Zone V?
- Up to what max height?
- What are the conditions one may impose for use of such a system for tall buildings?


Look forward ot hearing form you all on this topic


best regards,


CVR Murty
Swaminathan Krishnan
Alpa Sheth


Econference Moderators







Posted via Email
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shekhar at shekharpana...
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PostPosted: Tue Nov 20, 2012 1:01 pm    Post subject: Pointed discussions on tall buildings - Use of Flat Slab -co Reply with quote

Lets get going....

The three basic framing systems to resist lateral loads in high-rise buildings are: (1) Frames, (2)shear walls coupled or acting individually and (3) frames interacting with shear walls.
As an economical form of construction a shear wall structure incorporating a flat plate system is almost ideal.The flat plate system is very efficient in resisting gravity loading while the shear wall provides the resistance to lateral loads.

- Shekhar Panandiker

Please reply on our new id:
shekhar@shekharpanandiker.com (shekhar@shekharpanandiker.com) OR
info@shekharpanandiker.com (info@shekharpanandiker.com)

SHEKHAR PANANDIKER & ASSOCIATES,
Consulting Structural Engineers & Architects,
Wing A, second Floor, Hiraniketan,
Margao - Goa 403601

Tel: +91-832-2738399, 2705947
Fax: +91-832-2705947

Visit us at: www.shekharpanandiker.com
Quote:
-- Original Message --
From: Econf_Moderator (forum@sefindia.org)
To: econf34289@sefindia.org (econf34289@sefindia.org)
Sent: Tuesday, November 20, 2012 4:00 PM
Subject: [E-CONF] Pointed discussions on tall buildings - Use of Flat Slab -column with shear wall core as structural system


Dear All:

Not all of us design tall buildings. But most likely, a lot of us will be designers or project engineers for tall buildings in years to come. And needless to say, almost all of us have opinions about how things ought or ought not to be done.


We welcome comments from all engineers regarding issues they may want to comment on, on design and construction of tall buildings. If we look around us in Mumbai, NCR and most of the metros of Mumbai, majority of the new construction is tall buildings- and here I am using the IBC definition of 50 m. And almost everyone has done tall buildings, if I use the Chinese definition of 28m.


To start the ball rolling,


What is the general opinion of SEFIans to the use of flat slab with core shear wall system as a structural system for tall buildings?
- Should it be allowed in Zone V?
- Up to what max height?
- What are the conditions one may impose for use of such a system for tall buildings?


Look forward ot hearing form you all on this topic


best regards,


CVR Murty
Swaminathan Krishnan
Alpa Sheth


Econference Moderators







Posted via Email
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Dr. N. Subramanian
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PostPosted: Tue Nov 20, 2012 1:50 pm    Post subject: Re: Pointed discussions on tall buildings - Use of Flat Slab Reply with quote

Dear All,

I totally agree with Er Agarwal, as many cases of failures have been reported in the case of flat plates/slabs located in EQ zones. Flat plates in Zone V, even in ordinary buildings, is questionable without dual lateral force resisting system. Research in the area is still continuing.

The use of Stud shear reinforcement has been advocated and found to be better in increasing the shear strength of the slab than other types of shear reinforcement.

Best wishes,
NS
ishacon wrote:
Dear All,

Let us first be clear about using flat slab or flat plates -
the latter seems to have caught the fancy of contractors from Mumbai.

1. If it is flat plate, I would be reluctant to advocate it
for Zone V unless we do not insist on Dual system as per IS 1893,
due to the higher shear at shear wall and plate junctions.
May consider it for buildings up to 50 M height ensuring performance criteria
for human comfort in terms of the lateral drift.
In any case Flat slab with drop panel would be always more desirable
from performance basis. To what height , will still be a question I am not sure.

2. Having said as above, it becomes imperative that provisons of IS 1893 need to be
streamlined to determine appropriateTime period for shear wall buildings

VP Agarwal
ISHA CONSULTANTS (P) LTD
NEW DELHI 110074

PH : 011-2630 1158 ;
08010071749 ; 093 1345 2180
Quote:
-- Original Message --
From: Econf_Moderator (forum@sefindia.org)
To: econf34289@sefindia.org (econf34289@sefindia.org)
Sent: Tuesday, November 20, 2012 4:00 PM
Subject: [E-CONF] Pointed discussions on tall buildings - Use of Flat Slab -column with shear wall core as structural system


Dear All:

Not all of us design tall buildings. But most likely, a lot of us will be designers or project engineers for tall buildings in years to come. And needless to say, almost all of us have opinions about how things ought or ought not to be done.


We welcome comments from all engineers regarding issues they may want to comment on, on design and construction of tall buildings. If we look around us in Mumbai, NCR and most of the metros of Mumbai, majority of the new construction is tall buildings- and here I am using the IBC definition of 50 m. And almost everyone has done tall buildings, if I use the Chinese definition of 28m.


To start the ball rolling,


What is the general opinion of SEFIans to the use of flat slab with core shear wall system as a structural system for tall buildings?
- Should it be allowed in Zone V?
- Up to what max height?
- What are the conditions one may impose for use of such a system for tall buildings?


Look forward ot hearing form you all on this topic


best regards,


CVR Murty
Swaminathan Krishnan
Alpa Sheth


Econference Moderators







Posted via Email
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View user's profile Send private message
prasad_s
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Joined: 05 Sep 2012
Posts: 4
Location: PUNE

PostPosted: Tue Nov 20, 2012 1:58 pm    Post subject: Pointed discussions on tall buildings - Use of Flat Slab -co Reply with quote

Hello Isha mam,
Flat slab construction is not allowed in earthquake pron areas, which IS code indirectly says. Because there is no special provision for response reduction factor
which is to be applied for flat slabs. So i think may be we should opt a lesser value of response reduction factor for flat slab and study on its behaviour.
I just added to your comment. I am hoping a reply from you.
Regards,
Prasad Sansare,
IIT Rookee.


From: ishacon <forum@sefindia.org>
To: econf34289@sefindia.org
Sent: Tuesday, 20 November 2012 7:00 PM
Subject: [E-CONF] Re: Pointed discussions on tall buildings - Use of Flat Slab -co


           Dear All,

Let us first be clear about using flat slab or flat plates -
the latter seems to have caught the fancy of contractors from Mumbai.

1. If it is flat plate, I would be reluctant to advocate it
for Zone V unless we do not insist on Dual system as per IS 1893,
due to the higher shear at shear wall and plate junctions.
May consider it for buildings up to 50 M height ensuring performance criteria
for human comfort in terms of the lateral drift.
In any case Flat slab with drop panel would be always more desirable
from performance basis. To what height , will still be a question I am not sure.

2. Having said as above, it becomes imperative that provisons of IS 1893 need to be
streamlined to determine appropriateTime period for shear wall buildings

VP Agarwal
ISHA CONSULTANTS (P) LTD
NEW DELHI 110074

PH : 011-2630 1158 ;
08010071749 ; 093 1345 2180
      :                 -- Original Message --
From: Econf_Moderator (forum@sefindia.org (forum@sefindia.org))
To: econf34289@sefindia.org (econf34289@sefindia.org) (econf34289@sefindia.org (econf34289@sefindia.org))
Sent: Tuesday, November 20, 2012 4:00 PM
Subject: [E-CONF] Pointed discussions on tall buildings - Use of Flat Slab -column with shear wall core as structural system


Dear All:

Not all of us design tall buildings. But most likely, a lot of us will be designers or project engineers for tall buildings in years to come. And needless to say, almost all of us have opinions about how things ought or ought not to be done.


We welcome comments from all engineers regarding issues they may want to comment on, on design and construction of tall buildings. If we look around us in Mumbai, NCR and most of the metros of Mumbai, majority of the new construction is tall buildings- and here I am using the IBC definition of 50 m. And almost everyone has done tall buildings, if I use the Chinese definition of 28m.


To start the ball rolling,


What is the general opinion of SEFIans to the use of flat slab with core shear wall system as a structural system for tall buildings?
- Should it be allowed in Zone V?
- Up to what max height?
- What are the conditions one may impose for use of such a system for tall buildings?


Look forward ot hearing form you all on this topic


best regards,


CVR Murty
Swaminathan Krishnan
Alpa Sheth


Econference Moderators

Posted via Email
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kapildingare
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Joined: 15 May 2009
Posts: 103

PostPosted: Wed Nov 21, 2012 5:46 am    Post subject: Reply with quote

Resp. Sefians,
     As  Er. Shekhar has pointed ,
1) Flat plate with shear walls is most economical form of construction.
2) Along with that there are two other form of structural combinations that can be used to resist gravity and lateral loads as he has noted.
But  Resp  Dr Subramanian and Resp. Agrawal  has noted there are many cases of failures when in severe earthquake zone flat plates with shear walls as lateral load resisting system are used.
What I feel  is Er Shekhar has given vital information but  what Dr Subramanian is advising is more interesting .
BECAUSE  we can design  and  construct a building which can resist DESIGNED earthquake induced forces  with all three structural combinations Er Shekhar has mentioned but in case of earthquake of more intensities than designed one(as it is expected ) mode of failure or type and extent of damage /failure   will be different for all the three structural combinations. My opinion it will be worst in case of flat plate with shear walls.
I would like to get expert opinion on relative extent of damage with respect to these three forms when such structure is exposed to severe earthquake than designed earthquake.

                                                                                      Kapil Dingare
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SANGEETA WIJ
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Joined: 27 Jun 2012
Posts: 56

PostPosted: Wed Nov 21, 2012 6:03 am    Post subject: Pointed discussions on tall buildings - Use of Flat Slab -co Reply with quote

Dear Alpa
I had raised a query a few weeks ago to ask the following:
<![if !supportLists]>· <![endif]>whether there is a rule as to what % of tower columns must go to the basement raft level(hypothetically, the architect wants all tower columns to be supported only on transfer girders, let’s take a typical tower of G+20 and three basements which are full plot size). How does the overall tower stability get affected in such a case, especially in zone-IV EQ?
<![if !supportLists]>· <![endif]>What are the guidelines for Seismic separation/Expansion joints in such large basements(say it’s a 100 acre plot with 20 scattered towers).Do we or do we not give joints in the non-tower basement structure? If yes, then at what spacing? (chances are, that each part of basement may carry more than one tower, making it a very complex modelling challenge)
<![if !supportLists]>· <![endif]>When does the wind tunnel test become mandatory, between two adjacent high rise blocks?

Regards
Sangeeta Wij

From: shekhar at shekharpana... [mailto:forum@sefindia.org]
Sent: 21 November 2012 10:36
To: econf34289@sefindia.org
Subject: [E-CONF] Re: Pointed discussions on tall buildings - Use of Flat Slab -co



Lets get going....

The three basic framing systems to resist lateral loads in high-rise buildings are: (1) Frames, (2)shear walls coupled or acting individually and (3) frames interacting with shear walls.
As an economical form of construction a shear wall structure incorporating a flat plate system is almost ideal.The flat plate system is very efficient in resisting gravity loading while the shear wall provides the resistance to lateral loads.

- Shekhar Panandiker

Please reply on our new id:
shekhar@shekharpanandiker.com (shekhar@shekharpanandiker.com) (shekhar@shekharpanandiker.com (shekhar@shekharpanandiker.com)) OR
info@shekharpanandiker.com (info@shekharpanandiker.com) (info@shekharpanandiker.com (info@shekharpanandiker.com))

SHEKHAR PANANDIKER & ASSOCIATES,
Consulting Structural Engineers & Architects,
Wing A, second Floor, Hiraniketan,
Margao - Goa 403601

Tel: +91-832-2738399, 2705947
Fax: +91-832-2705947

Visit us at: www.shekharpanandiker.com
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anandkamath
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PostPosted: Wed Nov 21, 2012 7:06 am    Post subject: Pointed discussions on tall buildings - Use of Flat Slab -co Reply with quote

Dear AllWhy are not using steel structures with precast wall for tall buildings.RegardsAnandSent from BlackBerry® on Airtel
From: "kapildingare" <forum@sefindia.org>
Date: Wed, 21 Nov 2012 11:16:46 +0530
To: <econf34289@sefindia.org>
ReplyTo: econf34289@sefindia.org
Subject: [E-CONF] Re: Pointed discussions on tall buildings - Use of Flat Slab -co

     Resp. Sefians,      As Er. Shekhar has pointed , 1) Flat plate with shear walls is most economical form of construction. 2) Along with that there are two other form of structural combinations that can be used to resist gravity and lateral loads as he has noted. But Resp Dr Subramanian and Resp. Agrawal has noted there are many cases of failures when in severe earthquake zone flat plates with shear walls as lateral load resisting system are used. What I feel is Er Shekhar has given vital information but what Dr Subramanian is advising is more interesting . BECAUSE we can design and construct a building which can resist DESIGNED earthquake induced forces with all three structural combinations Er Shekhar has mentioned but in case of earthquake of more intensities than designed one(as it is expected ) mode of failure or type and extent of damage /failure will be different for all the three structural combinations. My opinion it will be worst in case of flat plate with shear walls.  I would like to get expert opinion on relative extent of damage with respect to these three forms when such structure is exposed to severe earthquake than designed earthquake.                                                                                        Kapil Dingare
        --

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mjnasar
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...


Joined: 26 Jan 2003
Posts: 51

PostPosted: Wed Nov 21, 2012 12:59 pm    Post subject: Fire Safety In Tall Buildings & Role of Structural Engin Reply with quote

Dear All,

Please tell us more about Fire safety & evacuations issue and structural engineers role in it

Following are the some points:

<![if !supportLists]>1- <![endif]>Standards of Fire rating in Hrs for Various structural elements
<![if !supportLists]>2- <![endif]>Role of Concrete covers / concrete encasement in Fire safety
<![if !supportLists]>3- <![endif]>Chemicals to improve fire ratings
<![if !supportLists]>4- <![endif]>Evacuation issues
<![if !supportLists]>5- <![endif]>Progressive collapse issues  
<![if !supportLists]>6- <![endif]>Blast Resistant construction for certain elements  

Regards
mjnasar










From: ishacon [mailto:forum@sefindia.org]
Sent: Tuesday, November 20, 2012 4:30 PM
To: econf34289@sefindia.org
Subject: [E-CONF] Re: Pointed discussions on tall buildings - Use of Flat Slab -co



Dear All,

Let us first be clear about using flat slab or flat plates -
the latter seems to have caught the fancy of contractors from Mumbai.

1. If it is flat plate, I would be reluctant to advocate it
for Zone V unless we do not insist on Dual system as per IS 1893,
due to the higher shear at shear wall and plate junctions.
May consider it for buildings up to 50 M height ensuring performance criteria
for human comfort in terms of the lateral drift.
In any case Flat slab with drop panel would be always more desirable
from performance basis. To what height , will still be a question I am not sure.

2. Having said as above, it becomes imperative that provisons of IS 1893 need to be
streamlined to determine appropriateTime period for shear wall buildings

VP Agarwal
ISHA CONSULTANTS (P) LTD
NEW DELHI 110074

PH : 011-2630 1158 ;
08010071749 ; 093 1345 2180    
:    
-- Original Message --
From: Econf_Moderator (forum@sefindia.org (forum@sefindia.org))
To: econf34289@sefindia.org (econf34289@sefindia.org) (econf34289@sefindia.org (econf34289@sefindia.org))
Sent: Tuesday, November 20, 2012 4:00 PM
Subject: [E-CONF] Pointed discussions on tall buildings - Use of Flat Slab -column with shear wall core as structural system


Dear All:

Not all of us design tall buildings. But most likely, a lot of us will be designers or project engineers for tall buildings in years to come. And needless to say, almost all of us have opinions about how things ought or ought not to be done.


We welcome comments from all engineers regarding issues they may want to comment on, on design and construction of tall buildings. If we look around us in Mumbai, NCR and most of the metros of Mumbai, majority of the new construction is tall buildings- and here I am using the IBC definition of 50 m. And almost everyone has done tall buildings, if I use the Chinese definition of 28m.


To start the ball rolling,


What is the general opinion of SEFIans to the use of flat slab with core shear wall system as a structural system for tall buildings?
- Should it be allowed in Zone V?
- Up to what max height?
- What are the conditions one may impose for use of such a system for tall buildings?


Look forward ot hearing form you all on this topic


best regards,


CVR Murty
Swaminathan Krishnan
Alpa Sheth


Econference Moderators

Posted via Email



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