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TALL Buildings Lateral Deflections

 
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u.mukesh
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PostPosted: Mon Nov 19, 2012 10:13 am    Post subject: TALL Buildings Lateral Deflections Reply with quote

Hello

How do we define tall buildings?
After how many stories or height "Wind load" would be
governing than "Earthquake load"?


Regards


Mukesh Upadhyay


On Mon, Nov 19, 2012 at 10:00 AM, Econf_Moderator <forum@sefindia.org (forum@sefindia.org)> wrote:
Quote:
            Not just dreaming to go Tall in India, but
Growing tall to build Tall in India…
  
Even as debates continue on whether or not Tall Buildings are needed in India, Tall Buildings are being built at a hectic pace in India. Architecture, design, material manufacture and construction firms from India and abroad are racing against time to provide services to this business venture. Tall Buildings seek higher level of engineering and architecture services. In particular, the attention is focused for the first time on fomalising some of the important building construction items, like MEP, utilities, services, facades, false ceilings/floors, building physics, building services automation, and maintenance. Sustainable development strategies in India require that we understand the implications of constructing these Tall Buildings, as we add them in large numbers in the major urban and semi-urban centers across India.
  
Independent of the realities and perils of constructing Tall Buildings, if India decides to build tall, then India needs to strengthen three of its existing systems. These are:
(1)  A strong technology base with
(a)  Focused Research and Development on all aspects of Tall Buildings, especially Geotechnical and Geophysical Investigations, Wind Tunnel Studies, Structural Behaviour under near-field earthquake ground motions and strong wind actions, and MEP services and other utilities;
(b)  Trained Manpower of Academics and Practioners (including Architects, Engineers and Contractors);
(c)   Proven construction materials (especially new materials, ï„ -ï„… curves of high strength concrete, lateral inplane response of structural glazing) and technologies; and
(d)  Code of Practice for Tall Building in India (which guides professionals on Geophysical and Geotechnical, Architectural, Structural, MEP, Fire and Constructional aspects);
(2)  A legally empowered body of regulators of Tall Buildings, with wings in every city and town interested in constructing Tall Buildings. Currently only Mumbai city has a Tall Building Committee, even though Tall Buildings are mushrooming across the country; and
(3) A change in the mental approach to designing and constructing such buildings. For instance, the usual construction practice needs to be halted of starting construction without designing the building. Unless the planning and designing of Tall Building is completed, even approvals for construction should not be issued by local municipal bodies.
  
            This e-Conference is an excuse for the professionals of the country to pause for a moment, look around on the realities (i.e., state-of-the-art and -of-the-practice of designing and constructing Tall Buildings worldwide), regroup our thoughts, build systems appropriate to development of Tall Buildings in India. Considering that we are starting late to prepare for this eventuality, it is only prudent to build from what the world has already leant and not rediscover the wheel of development of understanding and needed technology for Tall Buildings. I hope to participate in thought-provoking discussions through the week to understand the mind, the fears, the concerns, the challenges and the dreams of our professional community interested in Tall Buildings in India. I hope to take back to the drawing board some valuable inputs towards building the needed technology base for guiding the country on issues related to Tall Buildings, alongside formally discarding misconceptions and myths associated with Tall Buildings. Come build the bridge to the technology for a bright future of India…!!
  
Welcome to the e-Conference on Tall Buildings in India organized by SEFI.


C. V. R. Murty
     



     



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thirumalaichettiar
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PostPosted: Mon Nov 19, 2012 3:57 pm    Post subject: Reply with quote

Er. U.Mukesh, regarding the definition of Tall buildings:

Please refer the link below in which it was explained in details as below:

http://www.sefindia.org/forum/viewtopic.php?t=13016&postdays=0&postorder=asc&start=20


The Special Publication SP-240 by ACI on Performance based Design of Concrete building for Wind loads  is a very good book explaining the design of buildings against Wind Load.

In the above book Dr.M.C.Mota and Dr.B.S.Taranath have explained  in details on STRUCTURAL SYSTEMS FOR CONCRETE BUILDINGS . The content is in about 20 pages  in the SP.

In the above the buildings are classified under three categories as:

Low -rise: upto 4 stories.
Medium:  4 to 15 stories.
High-rise: 15 stories and above.

One should go through the book to know in addition to Smith and Dr.B.S.Taranaths's books.

As per the book "WIND LOADING STRUCTURES By Holmes" low-rise buildings:

are defined as roofed low-rise structures less than 15 m in height.

T.RangaRajan.
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thirumalaichettiar
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PostPosted: Mon Nov 19, 2012 4:56 pm    Post subject: Reply with quote

Pl.find some guide line on structural system.

T.RangaRajan.



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alpa_sheth
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PostPosted: Mon Nov 19, 2012 6:29 pm    Post subject: No Title Reply with quote

Mukesh, 

I think this is a very basic question and I do not think there will possibly be a single answer to what is a tall building. The IBC typically seems to call as 160' (~ 50m) building as a tall building. The Mumbai Highrise committee defines it as 70m min ht, the China code has a min height  of 28m for residential buildings to be called tall buildings and so on. 
Importantly, what should a unified Indian definition of tall buildings be? There is a push for defining them as 100m+ height or about greater than 30 stories but most of the towers in urban India are between 20 and 30 stories and it would mean that most multistory buildings would then be outside the gamut of tall building requirements, when we come up with them. 


I'd be curious to know  what is the opinion of other SEFIans on this issue. 


Regarding Wind vs Earthquake being governing design parameter- there really is no definitive answer. It will depend on the seismic zone, the geometric configuration - building shape etc. Its interesting to note that wind deformations in India are limited to h/500 while earthquake drift limit is H/250 which often times makes wind the governing load case from serviceability standpoint. Not so in international codes where there really is no difference in the value of wind and frequent earthquake drift limits. 




best regards,
Alpa 




On Mon, Nov 19, 2012 at 9:00 PM, u.mukesh <forum@sefindia.org (forum@sefindia.org)> wrote:
Quote:
           Hello

How do we define tall buildings?
After how many stories or height "Wind load" would be
governing than "Earthquake load"?


Regards


Mukesh Upadhyay


On Mon, Nov 19, 2012 at 10:00 AM, Econf_Moderator forum@sefindia.org (forum@sefindia.org))> wrote:
      :                            Not just dreaming to go Tall in India, but
Growing tall to build Tall in India…
 
Even as debates continue on whether or not Tall Buildings are needed in India, Tall Buildings are being built at a hectic pace in India. Architecture, design, material manufacture and construction firms from India and abroad are racing against time to provide services to this business venture. Tall Buildings seek higher level of engineering and architecture services. In particular, the attention is focused for the first time on fomalising some of the important building construction items, like MEP, utilities, services, facades, false ceilings/floors, building physics, building services automation, and maintenance. Sustainable development strategies in India require that we understand the implications of constructing these Tall Buildings, as we add them in large numbers in the major urban and semi-urban centers across India.
 
Independent of the realities and perils of constructing Tall Buildings, if India decides to build tall, then India needs to strengthen three of its existing systems. These are:
(1)  A strong technology base with
(a)  Focused Research and Development on all aspects of Tall Buildings, especially Geotechnical and Geophysical Investigations, Wind Tunnel Studies, Structural Behaviour under near-field earthquake ground motions and strong wind actions, and MEP services and other utilities;
(b)  Trained Manpower of Academics and Practioners (including Architects, Engineers and Contractors);
(c)   Proven construction materials (especially new materials, - curves of high strength concrete, lateral inplane response of structural glazing) and technologies; and
(d)  Code of Practice for Tall Building in India (which guides professionals on Geophysical and Geotechnical, Architectural, Structural, MEP, Fire and Constructional aspects);
(2)  A legally empowered body of regulators of Tall Buildings, with wings in every city and town interested in constructing Tall Buildings. Currently only Mumbai city has a Tall Building Committee, even though Tall Buildings are mushrooming across the country; and
(3) A change in the mental approach to designing and constructing such buildings. For instance, the usual construction practice needs to be halted of starting construction without designing the building. Unless the planning and designing of Tall Building is completed, even approvals for construction should not be issued by local municipal bodies.
 
            This e-Conference is an excuse for the professionals of the country to pause for a moment, look around on the realities (i.e., state-of-the-art and -of-the-practice of designing and constructing Tall Buildings worldwide), regroup our thoughts, build systems appropriate to development of Tall Buildings in India. Considering that we are starting late to prepare for this eventuality, it is only prudent to build from what the world has already leant and not rediscover the wheel of development of understanding and needed technology for Tall Buildings. I hope to participate in thought-provoking discussions through the week to understand the mind, the fears, the concerns, the challenges and the dreams of our professional community interested in Tall Buildings in India. I hope to take back to the drawing board some valuable inputs towards building the needed technology base for guiding the country on issues related to Tall Buildings, alongside formally discarding misconceptions and myths associated with Tall Buildings. Come build the bridge to the technology for a bright future of India…!!
 
Welcome to the e-Conference on Tall Buildings in India organized by SEFI.


C. V. R. Murty
     



     

     
     



     



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Vikas.Pai at Urs.com
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PostPosted: Tue Nov 20, 2012 9:55 am    Post subject: TALL Buildings Lateral Deflections Reply with quote

Hi Alpa,

Based on my nuclear, heavy civil and bridge sector experience, I would say that the natural frequency of the structure should be the defining parameter. Actually the lateral deflections are derived from the natural frequency calculations and should be treated as thumb rule. But for all buildings that do not follow general rules of aspect ratio, 'soft storey' and/or deemed to attract higher importance than normal, controlling natural frequency within limits shall be the only way of satisfying basic engineering principles. Codes are just the guidelines and not 'bible'. Engineering judgement of what would work in the conditions given are of paramount importance and hence would need to be formed on sound engineering principles.

Regards,

Eur Ing Vikas Pai CEng MIEI MPMI AMIStructE
Senior Engineer
URS Infrastructure & Environment UK Limited

Direct: +44 (0)1159 077 088
vikas.pai@urs.com


From: alpa_sheth [mailto:forum@sefindia.org]
Sent: 19 November 2012 19:30
To: econf34289@sefindia.org
Subject: [E-CONF] Re: No Title



Mukesh,Â

I think this is a very basic question and I do not think there will possibly be a single answer to what is a tall building. The IBC typically seems to call as 160' (~ 50m) building as a tall building. The Mumbai Highrise committee defines it as 70m min ht, the China code has a min height  of 28m for residential buildings to be called tall buildings and so on.Â
Importantly, what should a unified Indian definition of tall buildings be? There is a push for defining them as 100m+ height or about greater than 30 stories but most of the towers in urban India are between 20 and 30 stories and it would mean that most multistory buildings would then be outside the gamut of tall building requirements, when we come up with them.Â


I'd be curious to know  what is the opinion of other SEFIans on this issue.Â


Regarding Wind vs Earthquake being governing design parameter- there really is no definitive answer. It will depend on the seismic zone, the geometric configuration - building shape etc. Its interesting to note that wind deformations in India are limited to h/500 while earthquake drift limit is H/250 which often times makes wind the governing load case from serviceability standpoint. Not so in international codes where there really is no difference in the value of wind and frequent earthquake drift limits.Â




best regards,
AlpaÂ




On Mon, Nov 19, 2012 at 9:00 PM, u.mukesh forum@sefindia.org (forum@sefindia.org))> wrote:
:
Hello

How do we define tall buildings?
After how many stories or height "Wind load" would be
governing than "Earthquake load"?


Regards


Mukesh Upadhyay


On Mon, Nov 19, 2012 at 10:00 AM, Econf_Moderator forum@sefindia.org (forum@sefindia.org (forum@sefindia.org)))> wrote:
: Not just dreaming to go Tall in India, but
Growing tall to build Tall in India…
ÂÂÂ
Even as debates continue on whether or not Tall Buildings are needed in India, Tall Buildings are being built at a hectic pace in India. Architecture, design, material manufacture and construction firms from India and abroad are racing against time to provide services to this business venture. Tall Buildings seek higher level of engineering and architecture services. In particular, the attention is focused for the first time on fomalising some of the important building construction items, like MEP, utilities, services, facades, false ceilings/floors, building physics, building services automation, and maintenance. Sustainable development strategies in India require that we understand the implications of constructing these Tall Buildings, as we add them in large numbers in the major urban and semi-urban centers across India.
ÂÂÂ
Independent of the realities and perils of constructing Tall Buildings, if India decides to build tall, then India needs to strengthen three of its existing systems. These are:
(1) A strong technology base with
(a) Focused Research and Development on all aspects of Tall Buildings, especially Geotechnical and Geophysical Investigations, Wind Tunnel Studies, Structural Behaviour under near-field earthquake ground motions and strong wind actions, and MEP services and other utilities;
(b) Trained Manpower of Academics and Practioners (including Architects, Engineers and Contractors);
(c)  Proven construction materials (especially new materials, - curves of high strength concrete, lateral inplane response of structural glazing) and technologies; and
(d) Code of Practice for Tall Building in India (which guides professionals on Geophysical and Geotechnical, Architectural, Structural, MEP, Fire and Constructional aspects);
(2) A legally empowered body of regulators of Tall Buildings, with wings in every city and town interested in constructing Tall Buildings. Currently only Mumbai city has a Tall Building Committee, even though Tall Buildings are mushrooming across the country; and
(3) A change in the mental approach to designing and constructing such buildings. For instance, the usual construction practice needs to be halted of starting construction without designing the building. Unless the planning and designing of Tall Building is completed, even approvals for construction should not be issued by local municipal bodies.
ÂÂÂ
           This e-Conference is an excuse for the professionals of the country to pause for a moment, look around on the realities (i.e., state-of-the-art and -of-the-practice of designing and constructing Tall Buildings worldwide), regroup our thoughts, build systems appropriate to development of Tall Buildings in India. Considering that we are starting late to prepare for this eventuality, it is only prudent to build from what the world has already leant and not rediscover the wheel of development of understanding and needed technology for Tall Buildings. I hope to participate in thought-provoking discussions through the week to understand the mind, the fears, the concerns, the challenges and the dreams of our professional community interested in Tall Buildings in India. I hope to take back to the drawing board some valuable inputs towards building the needed technology base for guiding the country on issues related to Tall Buildings, alongside formally discarding misconceptions and myths associated with Tall Buildings. Come build the bridge to the technology for a bright future of India…!!
ÂÂÂ
Welcome to the e-Conference on Tall Buildings in India organized by SEFI.


C. V. R. Murty

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sureshkumar_kumaresan
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PostPosted: Tue Nov 20, 2012 11:24 pm    Post subject: Reply with quote

Hello,

Tall building definition shall also consider slenderness ratio not just the height. There is no definite answer to this and diverse definitions/limits all over the place. In my opinion, we need not worry too much on whether the building is tall or low. Our concern shall be whether any element or the entire structure is wind sensitive or not. For instance, in low buildings such as stadiums/airports, lateral wind force is not an issue, but uplift/downforce on the long-span roof is an issue and should be carefully studied.

With regard to which load dominates, as mdm Alpa rightly said this depends on many parameters. However, typically when number of floors above about 35 and slenderness ratio above 5-6, wind may govern the design. Rule of thump, as the buildings go higher and slenderness increases, the building becomes more flexible and will interact with wind more than earthquake as there is lot more energy with wind at low frequencies than earthquake does.

Suresh
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Ambalal
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PostPosted: Thu Nov 22, 2012 4:53 pm    Post subject: Reply with quote

Respected sir'.
I would like to share a very good definition for tall building from one of the text books i am referring for my final year project..
""Tall building may be defined as one that ,because of its height ,is effected by lateral forces due wind or earthquake action to an extent that they play an important role in the structural design""..
Im following this definition. Im interested in this topic because i have choose my final year project related to tall structure using steel..
thank you ..
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thirumalaichettiar
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PostPosted: Thu Nov 22, 2012 5:00 pm    Post subject: Reply with quote

Er.Ambalal, Why you are posting the same concept in two different topics?

It is enough at one place please.

T.RangaRajan.
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