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Welcome to the Econference on Design and Construction of Tal
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Indrajit_Chowdhury
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Joined: 06 Jul 2010
Posts: 26

PostPosted: Mon Nov 19, 2012 1:39 pm    Post subject: Welcome to the Econference on Design and Construction of Tal Reply with quote

I do not see any topic on dynamic soil structure interaction of tall buildings under earthquake force, is not a topic of importance???

Indrajit Chowdhury

From: drferozkottamal [mailto:forum@sefindia.org]
Sent: Monday, November 19, 2012 5:30 PM
To: econf34289@sefindia.org
Subject: [E-CONF] Re: Welcome to the Econference on Design and Construction of Tal



How to check safety against overturning, what should be the height aspect ratio, geometric proportioning...

On 19 November 2012 06:30, alpa_sheth forum@sefindia.org (forum@sefindia.org))> wrote:    
:    
Dear All:


Greetings and welcome to the E-conference on Design and Construction of Tall Buildings in India. As has been mentioned earlier the conference will run Nov. 19 through Nov 28.


A few pointers on Econference protocol.


* All topics pertaining to Tall Buildings may be discussed and we will urge all of you to participate in adding value to a topic with informed and well-thought out comments so as to maintain the standard of the Econference to international quality. We request that you please keep your subject note or comment on an issue crisp and topical.


* Any issues which are not core to the technical part of the Econference may please be discussed on the SpeakOut forum, not in the Econference, please.


* Kindly limit discussions to max of two issues pertaining to tall buildings in a single mail. The issues should be in different paragraphs. Also, when differing with another commentator, pl exercise utmost civility while expressing your disagreement.


We had suggested some topics for discussion and we had received valuable input from all of you. We have incorporated your suggestions and produced a revised list as under. This is not an exhaustive list and other pertinent technical issues can be added as required.


We have a list of subject experts for the Econference. We will introduce them along the way. We look forward to some exciting days ahead.....


warm regards,


Alpa Sheth
Prof CVR Murry
Prof Swaminathan Krishnan


Econference Moderators


************



Topics for Tall Buildings Conference

What do we define as a tall building?

a) Siting of tall buildings:
i Where are tall buildings allowed/not allowed to be sited?
b) Geotechnical Issues  
  • Soil Testing for Tall Buildings.  
  • Testing for establishing soil and pile modulus  


c) General Parameters of Tall Buildings  
  • Geometric Proportioning  
  • Height and Aspect Ratio  
  • General Distribution and area of Vertical and Lateral load carrying elements as % of plan area for concrete and steel structures.  
  • Min required stiffness of building  
  • Perimeter offset to avoid pounding  

d) Structural Configuration, Structural Systems and their Behaviour  
  • Selection of Structural system- Preliminary behavior analysis of alternative systems  
  • Discussion of Strucutral Sustems- Frames, Shear Walls, Frame-Shear Walls, Slab-Column Shear Wall structure, Tube Stucture, Hybrid Structure.....  
  • Performance of different structural systems;  
  • What levels of ductility are achievable in the lateral force resisting systems being constructed in India? What should the value of R be?  
  • Hybrid Structural Systems and their behaviour  
  • Achieving redundancy and alternative load path  


d) Load Combinations

e) Use of Masonry partition walls in tall buildings  
  • Should they be included in analysis?  
  • Should they be isolated from structure or not?  
  • Any special specifications for partition walls of tall buildings? (Light weight etc.)  



f) Modeling and Analysis  
  • Appropriate Modelling tools and soft ware for elastic, inelastic design for different systems and elements  



g) Structural Irregularities  
  • Should structural system transfer be allowed in tall buildings? If yes what are the limitations to be observed?  
  • Soft storey, Weak Storey  
  • How to deal with torsional irregularity? How much max modal mass may be excited in torsional modes of vibration?  


h) Wind Design  
  • When should Wind Tunnel Testing be carried out?  
  • What are the wind tunnel tests that should be carried out and to what effect? How to account for future buildings in the neighborhood in the layout and configurtion of adjacent buildings in the wind tunnel?  
  • What are the results to be asked from the WT testing agency?  
  • Appropriate Damping Values  
  • Discussion on Wind Dampers- When to use them, What type to use for what building application?  
  • Should there be instrumentation on tall buildings for measurement of vibrations/accelerations?  



i) Earthquake Analysis and Design  
  • Does the current IS 1893 assure acceptable performance of tall buildings?  
  • Seismic hazard characterization (base shear, response spectrum, ground motion histories, near-source effects, fault maps, fault classification w.r.t. earthquake potential characterization).  
  • Site soil characterization.  
  • Closely spaced modes-How critical is this issue?  
  • Linear static analysis procedure.  
  • Dynamic response spectrum procedure. What should the spectrum look like? When should a site-specific spectrum be required? How to account for near-source effects (applies to linear static procedure as well)?  
  • When should one do non-linear analysis? What are the earthquake ground motions to be considered in Indian scenario?  
  • How to properly account for P-Delta effects (modeling gravity columns)? Do we have software for nonlinear analysis readily available? Are test data characterizing component nonlinear (cyclic) behavior using prevailing Indian standards of practice available? What should the material models look like for various structural components?  
  • When is a pushover analysis required?  



j) Frame Structure -Ductile detailing criteria:  
  • · What criteria and when applicable?  
  • · Strong-column weak beam in moment frames  
  • · boundary elements in shear walls  
  • · tie-spacing  
  • · 135 degree hooks  
  • · lap-splices and development length  
  • · location of splices  
  • · beam-column joint detailing in concrete frames  
  • · continuity of column vertical rebar and beam longitudinal rebar through the joint  
  • · link beam detailing (diagonal rebar)  
  • · required level of diaphragm attachment on either side of a given length of wall, etc.  
  • · When and where is Capacity Design required?  
  • Column (gravity/lateral) design (include long-term axial shortening of columns due to creep and its effects on beams/floor slabs, etc.);  
  • Use of composite sections for creep control.  



k) Shear Wall

  • Wall design (include long-term axial shortening due to creep)  
  • Link beam design  
  • Diaphragm design  

l) Energy dissipation devices
  • viscous fluid dampers
  • added stiffness and damping devices


m) Use of Precast in Tall Building Construction  
  • Should it be permitted?  
  • To be used for which elements of structure?  
  • Design and detailing of joints?  
  • Behaviour in past earthquakes  

n) Foundations
a. Discussion on Piled raft foundations
· Allowable deformations
· Pile-raft interaction
· Analysis of piled rafts
. Shoring for Deep Basements
· Pile testing for deep piles
· Max allowable deformation of piles of piled raft- codal provisions?
· Deformations in piled raft?
· Differential settlement between core and perimeter. Provide a pour strip to minimize such settlement (when to provide). Additional moments in beams and slab due to such differential settlement.
· Design methodology and detailing of piles and rafts; lateral shear capacity of piles, vertical load carrying capacity of piles (skin friction vs bearing).
b. Raft foundations for tall buildings
c. Pile foundations for Tall buildings



o) Facades  
  • Stiffness  
  • Isolation; Designing the façade system to permit movement corresponding to wind and seismic drift limits.  



p) Tall Building with Podium issues  
  • Should tower be connected to Podium? When?  
  • Should Basement walls be considered in Analysis?  
  • Any special considerations to cater for large shear transfer in the podium diaphragm from tower? (refer ATC)  

q) Performance Criteria  
  • Serviceability Requirements  
  • What should be the limiting acceleration values for human comfort level in wind design?  
  • What is max drift to be allowed in wind and earthquake? What can be the sudden spike in interstorey drift due to a soft/weak storey?  

r) Performance Based (Seismic) Design of Structures  
  • When to do this?  
  • How to do it?  
  • Review Procedures ....  

s) Other Detailing Aspects of Tall Buildings  
  • Detailing of cold joints (Core and floor slab done separately)  
  • Dealing with congestion of steel  
  • Splices/Anchorages  
  • Expansion Joint issues  
  • Seismic joints: When to use and how to design.  
  • Design of Inclines Columns, Bracings etc.


t) Construction Issues of Tall Buildings  
  • Modular/Lightweight shuttering  
  • Slipform Shuttering  
  • High strength concretes – Issues of microcracking, delayed strength, additives, flyash, silica fumes etc.  
  • High Grade Steel- Inconsistency in yield stress.  
  • Dealing with congestion of steel in beam-column joints  
  • Vertical Transportation of concrete  
  • Durability of Tall Buildings- How to repair/retrofit?  
  • Concrete grade of columns vs. concrete grade of slabs – How to deal with difference?  

u) Construction Specifications  
  • Materials (including welds, rebar, concrete, structural steel, etc.)  
  • Structural, Mechanical, Electrical, Plumbing, Vertical Transportation systems  
  • Site preparation and managementa



v) Green Building Issues













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chinmayrshah
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Joined: 21 Aug 2011
Posts: 5

PostPosted: Mon Nov 19, 2012 5:34 pm    Post subject: Paper Presentation? Reply with quote

I had a research project about "Stability Aspects of Tall Commercial Buildings in Earthquake and Recent Practices". Is there any provision of presenting such papers in this e-Conference?

Thanks in advance
Chinmay
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Meera P
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Joined: 11 May 2009
Posts: 21

PostPosted: Tue Nov 20, 2012 4:38 am    Post subject: Welcome to the Econference on Design and Construction of Tal Reply with quote

Sir/mam,

1.  The compression of columns under self weight  : In very tall buildings, will this be a issue to be considered, how to allow for it ? Will P-Delta analysis take care of this ?
thanks and regrds
meera p



On Mon, Nov 19, 2012 at 11:00 AM, Econf_Moderator <forum@sefindia.org (forum@sefindia.org)> wrote:
Quote:
           Dear All: 


Greetings and welcome to the E-conference on Design and Construction of Tall Buildings in India. As has been mentioned earlier the conference will run Nov. 19 through Nov 28. 


A few pointers on Econference protocol. 



* All topics pertaining to Tall Buildings may be discussed and we will  urge all of you to participate in adding value to a topic with informed and well-thought out comments so as to maintain the  standard of the Econference to international quality. We request that you please keep your subject note or comment on an issue crisp and  topical. 


* Any issues which are not core to the technical part of the Econference may please be discussed on the SpeakOut forum, not in the Econference, please. 


* Kindly limit  discussions to   max of two issues pertaining to tall buildings  in a single mail. The issues should be in different paragraphs. Also, when differing with another commentator, pl exercise utmost civility while expressing  your disagreement. 


We had suggested some topics for discussion and we had received valuable input from all of you. We have incorporated your suggestions and produced a revised list as under. This is not an exhaustive list and other pertinent technical issues can be added as required. 


We have a list of subject experts for the Econference. We will introduce them along the way. We look forward to some exciting days ahead..... 


warm regards,


Alpa Sheth 
Prof CVR Murry
Prof Swaminathan Krishnan 


Econference Moderators 


*********************

           

Topics for Tall Buildings Conference
  
What do we define as a tall building?

a)      Siting of tall buildings:  
      i Where are tall buildings allowed/not allowed to be sited?
b)      Geotechnical  Issues 
  •   Soil Testing for Tall Buildings. 
  •   Testing for establishing soil and pile modulus 

c)      General Parameters of Tall Buildings 
  •  Geometric Proportioning 
  •  Height and Aspect Ratio 
  •  General Distribution and area of  Vertical  and Lateral load carrying elements as % of plan area for concrete and steel structures. 
  • Min required stiffness of building 
  • Perimeter offset to avoid pounding 
d)       Structural Configuration, Structural Systems and their Behaviour 
  •   Selection of Structural system- Preliminary behavior analysis   of alternative systems 
  • Discussion of Strucutral Sustems- Frames, Shear Walls, Frame-Shear Walls, Slab-Column Shear Wall structure, Tube Stucture, Hybrid Structure.....  
  •   Performance of different structural systems; 
  •   What levels of ductility are achievable in the lateral force resisting systems being constructed in India?  What should the value of R be? 
  • Hybrid Structural Systems and their behaviour   
  •  Achieving  redundancy and alternative load path 

d)      Load Combinations 

e)       Use of Masonry partition walls in tall buildings
  •  Should they be included in  analysis? 
  •  Should they be isolated from structure or not? 
  •  Any special specifications for partition walls of  tall buildings?  (Light weight etc.) 


f)      Modeling and Analysis
  • Appropriate Modelling tools and soft ware for elastic, inelastic design for different systems and elements 

 
g)      Structural Irregularities
  • Should structural system transfer be allowed in tall buildings? If yes what are the limitations to be observed? 
  • Soft storey, Weak Storey 
  • How to deal with torsional irregularity? How much max  modal mass may be excited in torsional modes of vibration? 

h)        Wind Design
  •  When should Wind Tunnel Testing be carried out? 
  • What are the wind tunnel  tests that should be carried out and to what effect?  How to account for future buildings in the neighborhood in the layout and configurtion of adjacent buildings in the wind tunnel?   
  • What are the results to be asked from the WT testing agency? 
  • Appropriate Damping Values 
  • Discussion on Wind Dampers- When to use them, What type to use for what building application? 
  • Should there be instrumentation on tall buildings for measurement of vibrations/accelerations?   

 
i)        Earthquake Analysis and Design
  • Does the current IS 1893 assure acceptable performance of tall buildings? 
  • Seismic hazard characterization (base shear, response spectrum, ground motion histories, near-source effects, fault maps, fault classification w.r.t. earthquake potential characterization).   
  • Site soil characterization. 
  • Closely spaced modes-How critical is this issue?   
  •   Linear static analysis procedure. 
  •  Dynamic response spectrum procedure.  What should the spectrum look like?  When should a site-specific spectrum be required?  How to account for near-source effects (applies to linear static procedure as well)?   
  • When should one do non-linear analysis? What are the earthquake ground motions to be considered in Indian scenario?  
  •  How to properly account for P-Delta effects (modeling gravity columns)?  Do we have software for nonlinear analysis readily available?  Are test data  characterizing component nonlinear (cyclic) behavior using prevailing Indian standards of practice available?  What should the material models look like for various structural components?   
  •  When is a pushover analysis required? 

          
j)        Frame Structure -Ductile detailing criteria:  

  • ·   What criteria and when applicable?  
  • ·   Strong-column weak beam in moment frames 
  • ·    boundary elements in shear walls 
  • ·    tie-spacing 
  • ·    135 degree hooks 
  • ·    lap-splices and development length 
  • ·    location of splices 
  • ·    beam-column joint detailing in concrete frames 
  • ·    continuity of column vertical rebar and beam longitudinal rebar through the joint 
  • ·    link beam detailing (diagonal rebar) 
  • ·    required level of diaphragm attachment on either side of a given length of wall, etc. 
  • ·   When and where is Capacity Design required? 
  •   Column (gravity/lateral) design (include long-term axial shortening of columns due to creep and its effects on beams/floor slabs, etc.); 
  •  Use of composite sections for creep control. 


k) Shear Wall 


  • Wall design (include long-term axial shortening due to creep) 
  •   Link beam design 
  •  Diaphragm design 
l) Energy dissipation devices
  • viscous fluid dampers
  • added stiffness and damping devices

m)       Use of Precast in Tall Building Construction 
  • Should it be permitted? 
  • To be used for which  elements of structure? 
  • Design and detailing of joints? 
  • Behaviour in past earthquakes 
n)        Foundations
a.       Discussion on Piled raft foundations
·   Allowable deformations
·   Pile-raft interaction
·   Analysis of piled rafts 
.   Shoring for Deep Basements   
·   Pile testing for deep piles 
·   Max allowable deformation of piles of piled raft- codal provisions?
·   Deformations in piled raft?
·   Differential settlement between core and perimeter.  Provide a pour strip to minimize such settlement (when to provide).  Additional moments in beams and slab due to such differential settlement.
·   Design methodology and detailing of piles and rafts; lateral shear capacity of piles, vertical load carrying capacity of piles (skin friction vs bearing).
b.      Raft  foundations for tall buildings
c.       Pile foundations for Tall buildings 


 
o)    Facades
  • Stiffness 
  • Isolation;  Designing the façade system to permit movement corresponding to wind and seismic drift limits. 


p)      Tall Building with Podium issues
  • Should tower be connected to Podium?  When? 
  • Should Basement walls be considered in Analysis? 
  •  Any special considerations to cater for large shear transfer in the podium diaphragm from tower? (refer ATC)   
q)      Performance Criteria
  • Serviceability Requirements 
  • What should be the limiting acceleration values for human comfort level in wind design? 
  • What is max drift to be allowed in wind and earthquake?  What can be the sudden spike in interstorey drift due to a soft/weak storey?   
r)      Performance Based (Seismic) Design of Structures
  • When to do this? 
  • How to do it? 
  • Review Procedures .... 
s)      Other Detailing Aspects of Tall Buildings
  •  Detailing of cold joints (Core and floor slab done separately) 
  • Dealing with congestion of steel 
  • Splices/Anchorages 
  • Expansion Joint issues 
  • Seismic joints:  When to use and how to design. 
  • Design of Inclines Columns, Bracings etc.

t)       Construction Issues of Tall Buildings
  • Modular/Lightweight shuttering 
  • Slipform Shuttering 
  • High strength concretes – Issues of microcracking, delayed strength, additives, flyash, silica fumes etc. 
  • High Grade Steel- Inconsistency in yield stress.  
  • Dealing with congestion of steel  in beam-column joints 
  • Vertical Transportation of concrete 
  • Durability of Tall Buildings- How to repair/retrofit? 
  • Concrete grade of columns vs. concrete grade of slabs – How to deal with difference? 
u)       Construction Specifications
  • Materials (including welds, rebar, concrete, structural steel, etc.) 
  • Structural, Mechanical, Electrical, Plumbing, Vertical Transportation systems 
  • Site preparation and managementa
     

v)        Green Building Issues 

************
     



     



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sunilgurtoo
SEFI Member
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Joined: 14 Dec 2011
Posts: 3

PostPosted: Tue Nov 20, 2012 5:10 am    Post subject: Welcome to the Econference on Design and Construction of Tal Reply with quote

Hi Everyone,

I would like to know, in TALL Buildings overseas people use STUD RAILS for PUNCHING Shear Reinforcement, In India why this practise is not being used.
We have introduced the DECON Stud Rails and have supplied to 4-5 projects wherein these buildings are 8-9 floors.

Will the STUD RAIL concept good for the TALL Buildings in India.

Sunil Gurtoo
JORDAHL/DECON India


From: partha at adaptsoft.com [mailto:forum@sefindia.org]
Sent: 20 November 2012 10:24
To: econf34289@sefindia.org
Subject: [E-CONF] Re: Welcome to the Econference on Design and Construction of Tal



Thank you for starting such an informative session. While I go through the topic I have following comments:

1. What should be ideal classification of Tall Building?

2. About Material, let us talk more Steel and Post Tension Concrete. As use of Reinforced Concrete will reduce the head room (for the presence of beam and thicker slab) and increase the building weight thus experience higher magnitude of Seismic Force.

3. Can we have a single document (according to the topics) containing details at the end of the conference?

Regards,

Partha Pratim Roy
Vice President (Technical)
ADAPT Concrete Software
www.adaptsoft.com



From: Econf_Moderator (forum@sefindia.org (forum@sefindia.org))
Sent: Monday, November 19, 2012 11:00 AM
To: econf34289@sefindia.org (econf34289@sefindia.org) (econf34289@sefindia.org (econf34289@sefindia.org))
Subject: [E-CONF] Re: Welcome to the Econference on Design and Construction of Tal




Dear All:


Greetings and welcome to the E-conference on Design and Construction of Tall Buildings in India. As has been mentioned earlier the conference will run Nov. 19 through Nov 28.


A few pointers on Econference protocol.



* All topics pertaining to Tall Buildings may be discussed and we will urge all of you to participate in adding value to a topic with informed and well-thought out comments so as to maintain the standard of the Econference to international quality. We request that you please keep your subject note or comment on an issue crisp and topical.


* Any issues which are not core to the technical part of the Econference may please be discussed on the SpeakOut forum, not in the Econference, please.


* Kindly limit discussions to max of two issues pertaining to tall buildings in a single mail. The issues should be in different paragraphs. Also, when differing with another commentator, pl exercise utmost civility while expressing your disagreement.


We had suggested some topics for discussion and we had received valuable input from all of you. We have incorporated your suggestions and produced a revised list as under. This is not an exhaustive list and other pertinent technical issues can be added as required.


We have a list of subject experts for the Econference. We will introduce them along the way. We look forward to some exciting days ahead.....


warm regards,


Alpa Sheth
Prof CVR Murry
Prof Swaminathan Krishnan


Econference Moderators


************



Topics for Tall Buildings Conference

What do we define as a tall building?

a) Siting of tall buildings:
i Where are tall buildings allowed/not allowed to be sited?
b) Geotechnical Issues
  • Soil Testing for Tall Buildings.
  • Testing for establishing soil and pile modulus


c) General Parameters of Tall Buildings
  • Geometric Proportioning
  • Height and Aspect Ratio
  • General Distribution and area of Vertical and Lateral load carrying elements as % of plan area for concrete and steel structures.
  • Min required stiffness of building
  • Perimeter offset to avoid pounding

d) Structural Configuration, Structural Systems and their Behaviour
  • Selection of Structural system- Preliminary behavior analysis of alternative systems
  • Discussion of Strucutral Sustems- Frames, Shear Walls, Frame-Shear Walls, Slab-Column Shear Wall structure, Tube Stucture, Hybrid Structure.....
  • Performance of different structural systems;
  • What levels of ductility are achievable in the lateral force resisting systems being constructed in India? What should the value of R be?
  • Hybrid Structural Systems and their behaviour
  • Achieving redundancy and alternative load path


d) Load Combinations

e) Use of Masonry partition walls in tall buildings
  • Should they be included in analysis?
  • Should they be isolated from structure or not?
  • Any special specifications for partition walls of tall buildings? (Light weight etc.)



f) Modeling and Analysis
  • Appropriate Modelling tools and soft ware for elastic, inelastic design for different systems and elements



g) Structural Irregularities
  • Should structural system transfer be allowed in tall buildings? If yes what are the limitations to be observed?
  • Soft storey, Weak Storey
  • How to deal with torsional irregularity? How much max modal mass may be excited in torsional modes of vibration?


h) Wind Design
  • When should Wind Tunnel Testing be carried out?
  • What are the wind tunnel tests that should be carried out and to what effect? How to account for future buildings in the neighborhood in the layout and configurtion of adjacent buildings in the wind tunnel?
  • What are the results to be asked from the WT testing agency?
  • Appropriate Damping Values
  • Discussion on Wind Dampers- When to use them, What type to use for what building application?
  • Should there be instrumentation on tall buildings for measurement of vibrations/accelerations?



i) Earthquake Analysis and Design
  • Does the current IS 1893 assure acceptable performance of tall buildings?
  • Seismic hazard characterization (base shear, response spectrum, ground motion histories, near-source effects, fault maps, fault classification w.r.t. earthquake potential characterization).
  • Site soil characterization.
  • Closely spaced modes-How critical is this issue?
  • Linear static analysis procedure.
  • Dynamic response spectrum procedure. What should the spectrum look like? When should a site-specific spectrum be required? How to account for near-source effects (applies to linear static procedure as well)?
  • When should one do non-linear analysis? What are the earthquake ground motions to be considered in Indian scenario?
  • How to properly account for P-Delta effects (modeling gravity columns)? Do we have software for nonlinear analysis readily available? Are test data characterizing component nonlinear (cyclic) behavior using prevailing Indian standards of practice available? What should the material models look like for various structural components?
  • When is a pushover analysis required?



j) Frame Structure -Ductile detailing criteria:
  • · What criteria and when applicable?
  • · Strong-column weak beam in moment frames
  • · boundary elements in shear walls
  • · tie-spacing
  • · 135 degree hooks
  • · lap-splices and development length
  • · location of splices
  • · beam-column joint detailing in concrete frames
  • · continuity of column vertical rebar and beam longitudinal rebar through the joint
  • · link beam detailing (diagonal rebar)
  • · required level of diaphragm attachment on either side of a given length of wall, etc.
  • · When and where is Capacity Design required?
  • Column (gravity/lateral) design (include long-term axial shortening of columns due to creep and its effects on beams/floor slabs, etc.);
  • Use of composite sections for creep control.



k) Shear Wall

  • Wall design (include long-term axial shortening due to creep)
  • Link beam design
  • Diaphragm design

l) Energy dissipation devices
  • viscous fluid dampers
  • added stiffness and damping devices


m) Use of Precast in Tall Building Construction
  • Should it be permitted?
  • To be used for which elements of structure?
  • Design and detailing of joints?
  • Behaviour in past earthquakes

n) Foundations
a. Discussion on Piled raft foundations
· Allowable deformations
· Pile-raft interaction
· Analysis of piled rafts
. Shoring for Deep Basements
· Pile testing for deep piles
· Max allowable deformation of piles of piled raft- codal provisions?
· Deformations in piled raft?
· Differential settlement between core and perimeter. Provide a pour strip to minimize such settlement (when to provide). Additional moments in beams and slab due to such differential settlement.
· Design methodology and detailing of piles and rafts; lateral shear capacity of piles, vertical load carrying capacity of piles (skin friction vs bearing).
b. Raft foundations for tall buildings
c. Pile foundations for Tall buildings



o) Facades
  • Stiffness
  • Isolation; Designing the façade system to permit movement corresponding to wind and seismic drift limits.



p) Tall Building with Podium issues
  • Should tower be connected to Podium? When?
  • Should Basement walls be considered in Analysis?
  • Any special considerations to cater for large shear transfer in the podium diaphragm from tower? (refer ATC)

q) Performance Criteria
  • Serviceability Requirements
  • What should be the limiting acceleration values for human comfort level in wind design?
  • What is max drift to be allowed in wind and earthquake? What can be the sudden spike in interstorey drift due to a soft/weak storey?

r) Performance Based (Seismic) Design of Structures
  • When to do this?
  • How to do it?
  • Review Procedures ....

s) Other Detailing Aspects of Tall Buildings
  • Detailing of cold joints (Core and floor slab done separately)
  • Dealing with congestion of steel
  • Splices/Anchorages
  • Expansion Joint issues
  • Seismic joints: When to use and how to design.
  • Design of Inclines Columns, Bracings etc.


t) Construction Issues of Tall Buildings
  • Modular/Lightweight shuttering
  • Slipform Shuttering
  • High strength concretes – Issues of microcracking, delayed strength, additives, flyash, silica fumes etc.
  • High Grade Steel- Inconsistency in yield stress.
  • Dealing with congestion of steel in beam-column joints
  • Vertical Transportation of concrete
  • Durability of Tall Buildings- How to repair/retrofit?
  • Concrete grade of columns vs. concrete grade of slabs – How to deal with difference?

u) Construction Specifications
  • Materials (including welds, rebar, concrete, structural steel, etc.)
  • Structural, Mechanical, Electrical, Plumbing, Vertical Transportation systems
  • Site preparation and managementa



v) Green Building Issues

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PostPosted: Tue Nov 20, 2012 2:35 pm    Post subject: Welcome to the Econference on Design and Construction of Tal Reply with quote

Dear All,

It would be great if following topics are also included in the discussions pertaining to Tall Buildings :

<![if !supportLists]>a) <![endif]>Design Strategy (if any) to prevent complete collapse of Building under terror attacks (Post 9/11).  
<![if !supportLists]>b) <![endif]>Infusion of any new building material, which we look forward to for achieving newer height of TALL BUILDINGS
<![if !supportLists]>c) <![endif]>Importance of Liquefaction Analysis in case of TALL BUILDINGS, particularly in seismic prone areas.

Best Wishes

Alok Bhowmick

From: sunilgurtoo [mailto:forum@sefindia.org]
Sent: Tuesday, November 20, 2012 11:00 AM
To: econf34289@sefindia.org
Subject: [E-CONF] Re: Welcome to the Econference on Design and Construction of Tal




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PostPosted: Tue Nov 20, 2012 5:43 pm    Post subject: Econference on Design and Construction of Tall Buildings in Reply with quote

Pre-Stressing as a Green Building Issue:
- Saibal Saha, Sr. Manager (Civil Design), Usha Martin Ltd. (saibalsaha2@gmail.com (saibalsaha2@gmail.com))
[ Accredited Professional- Indian Green Building Council]
[Certified Energy Manager/Energy Auditor- Bureau of Energy Efficiency, Govt. Of India]

  • For any form of Green Building Concept, we are concerned of “Life-Cycle Consumption of Energy by a Building”

  • At the time of construction of a building, we use materials, machineries and labourers,

  • Every building-material & machinery has a tag of 'Embodied Energy', whereas machineries & laboures/operators have some operating energy consumptions also.

  • Now if we can reduce the consumption of building- materials as well as construction time substantially, those Embodied Energies as well as operational energies for the construction of that particular building would be much lowered, thus championing the concept of “Green Building”.

  • The above statement is true for any type of building irrespective of its height, use-group, location etc. However it is particularly more appropriate for “Tall Buildings”.

  • Because to build a “Tall Building”, we need a huge quantity of materails and a long period of time. By cutting a mere percentage of these resources could have a huge impact from Energy point of view as well as Environmental concerns. As production of conventional energy is nothing but generation of GHGs also.

  • But how can we reduce the consumption of materials and lowers the construction time:

    1. Firstly if we adopt Pre Stressed Concrete Slab Construction instead of conventional RCC slab with or without changing the framing plan as required by architectural design, dimensions of the members could be reduced at least by 15-20%, thus reducing the use of Concrete. Moreover Rebar consumption also has to be reduced in a significant amount. Hence use of PSC in place of RCC has a potential of reduction in consumption of Embodied Energy per unit of built up area, having sizable impact on Energy and Environment.

    2. Secondly we can reduce the construction time significantly by using the above stated technology. In conventional RCC we have to wait to get a 2/3rd strength of designed concrete before stripping of formwork or 7-10 days as per the size of span length. However in PSC we can start stripping on 4th day of casting, because it depends on a specific value of cube strength(25 MPa) of concrete and if it is reached within 3rd day of concreting which is very common in case of high strengths concrete (M40 and beyond), it is amply possible. Thus PSC has a capability to reduce the “Time-Cycle” of slabcasting in repititive manner which is very typical in Tall Buildings. For example in case of a 50 storied building it has potential of saving 250 or more days in casting of the entire building.

  • Last but not the least, since we are discussing the subject in terms of “Life Cycle Energy Consumption by a Building”, we definitely should focus of longivity of the building while servicable. Since PSC concrete is almost Crack-Free, it enhances the durability of the concrete and hence its life span. Therefore use of PSC, in long term delay the necessity of replacing the old building by a new one which ultimately consumes vigin resources (having a tag of Embodied Energy) from this earth again, to be constructed.


Idealisation in Software Tools and Structural Irregularities:
- Partha Pratim Roy, B. E. (Civil); M. E. (Structure); A. I. E.
Vice President (Technical), ADAPT International (pproy76@gmail.com)
When it comes to the analysis and design of Tall Building it is extremely important to idealise the correct mathematical model while using any software tool like STAAD, ETABS, ROBOT etc. It is often noticed engineers prepare a frame model consisting of Beams and Columns and perform a First Order Linear Analysis. These leads to following issues which becomes very critical and leads to inaccuracy.  

Modelling of Floor Slab:

  1. Residential administrative, office, educational and many other buildings and structures are made of continuous floor slabs without any opening. Industrial buildings, on the other hand, in many cases are having different sizes of cut-outs in the floor.  

  2. Presence of Slab not only contribute vertical loading but also impart a horizontal diaphragm action in the structure due to large in-plane stiffness of floor slabs.  

  3. Dynamic behaviour of a structure modelled taking into account the stiffness of the floor slab shows wide differences to that modelled without floor slab.  

  4. A floor slab can be modelled in two ways which are available in almost all software tools:

    1. By including plane stress elements

    2. By using master slave command


Soil-Structure Interaction:

  1. Generally engineers assume that the foundation is fixed in space. But, depending on the nature of soil, the base of the structure undergoes deformations. The soil can be seen as a spring with certain stiffness.  

  2. In almost all software tools, besides “Fixed”or “Pinned” options, user can also assign soil-springs by the User Defined or Fixed But option. Tools like Autodesk's Robot Structural Analysis even allow user to model soil strata at different levels with all parameters including its stiffness and damping ratio. Also utilities like Automatic soil-spring generation (i.e. MAT) can also be availed .

  3. In seismic analysis problems, research works has shown that a certain mass of soil vibrates along with the foundation. But no soil-mass is included in the model, as no specific guideline is yet available. Only stiffness and damping ratios of the soil-springs are generally included in a mathematical model.

  4. The spring constant of soil springs depends on factors like shear modulus of soil, Poisson's ratio of soil, foundation dimensions, and shear-wave velocity through the soil-strata.

  5. During dynamic analysis the damping ratios of the soil-spring may be obtained by summing two quantities: material damping and geometric damping of the soil-spring.

  6. Formulations of soil-spring stiffness and damping ratio are available in text books on machine foundations.  

  7. Once can analyse the same Building Frame using the same Software Tools with two different Spring Stiffness (say, 10E+10 kN/m^2/m run for Hard Soil and 10E+04 kN/m^2/m run for Soft Soil) it may be observed that the response is very much sensitive to soil-spring stiffness. Higher soil-spring stiffness increases overall stiffness of the structure, resulting in lowering of fundamental periods and attract more seismic force (increasing base shear).  

  8. The participation of soil in vibration is also altered which may be reflected by the values of composite modal damping.


Soft Storey and Modelling of Shear Walls

  1. According to IS 1893-2002 (Part 1), there are two types of stiffness irregularities as given below:

    1. A soft storey is one in which the lateral stiffness is less than 70% of that in the storey above or less than 80% of the average lateral stiffness of the three storeys above.

    2. An extreme soft storey is one in which the lateral stiffness is less than 60% of that in the storey above or less than 70% of the average lateral stiffness of the three storeys above.

  2. The lateral stiffness of a vertical element (column or wall) of a building frame is equal to (12*E*I/L^3). The lateral stiffness of a storey is the summation of the lateral stiffness of all columns and walls in that storey.  

  3. It is important to check Soft Storey and thus the modelling of Shear Wall is very much important as it will affect stiffness of the particular floor.  

  4. Some engineers even model compression only member or strut to resemble the presence of Brick Walls or Non-structural Partition Walls. However no specific guideline is available about formulation of equivalent strut members.


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PostPosted: Tue Nov 20, 2012 9:02 pm    Post subject: Re: Welcome to the Econference on Design and Construction of Reply with quote

Dear Er Sunil,

Stud rails or Stud reinforcement does not have any connection with tall buildings, but has connection with flat plates. They are to be used only when the punching shear strength of the slab is less than the applied punching shear at the column-slab joint. There are other methods of increasing the punching shear strength, though stud reinforcement has been found to be more efficient.

It is good to know that DECON Stud rails are available in India (is it not introduced in India 6-7 years back?). Stud reinforcement(double headed studs) can also be used as ties in columns and also as shear reinforcements. The following paper explores the use of studs in Corbels:
Birkle,G.,  Ghali, A. and Schafer, K., Double-Headed Studs Improve Corbel Reinforcement, Concrete International, Vol. 24, No.9,      September 1, 2002, pp.

Best wishes,
NS
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PostPosted: Wed Nov 21, 2012 12:44 pm    Post subject: Reply with quote

Meera P,
Elastic compression of columns shall be taken into consideration in the analysis & design. Storey Height of tall buildings at lower level will be kept more than at the upper levels to account for this deformation.
Regards
RL Dinesh
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PostPosted: Thu Nov 22, 2012 4:14 am    Post subject: Welcome to the Econference on Design and Construction of Tal Reply with quote

As pointed out by Eng. Meera, the designers of high -rise buildings have to consider column length changes due to elastic stresses caused by gravity loads, creep caused by gravity loads, drying shrinkage and temperature variations. These type of distortions appeared in earlier buildings & neglecting their effects rarely resulted in deficiencies in the serviceability of the structures. But with reduced overall stiffness due to use of high grade concretes and with increase in height the volume changes effects became magnified and could no longer be treated as secondary considerations in design.
Elastic column shortening refers to the immediate axial deformation caused by the loading on the columns & is a function of the loads, column cross section and modulus of elasticity of the concrete and time of loading. Column shortening due to creep is the time dependent. The shortening due to creep is much smaller than that caused by shrinkage. Column shortening due to shrinkage is the axial column deformation caused by shrinkage of column concrete. Column length changes in a high-rise building have structural as well as non-structural implications. For example if we have two columns initially supporting equal loads and one shortens more than the other, the shorter column will end up taking less load than the taller one, Load will flow from the more deformable column to the stiffer column. A major consequence of differential column shortening is slab tilt which in turn will cause non-structural partitions to rotate and distort. The structural effects can be quite severe if the differentially shortening columns are close to one another.
Request the experts to elaborate and give their expert comments on these issues.

- 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
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Visit us at: www.shekharpanandiker.com
[quote] -- Original Message --
From: Meera P (forum@sefindia.org)
To: econf34289@sefindia.org (econf34289@sefindia.org)
Sent: Wednesday, November 21, 2012 5:41 PM
Subject: [E-CONF] Re: Welcome to the Econference on Design and Construction of Tal


Sir/mam,

1. The compression of columns under self weight : In very tall buildings, will this be a issue to be considered, how to allow for it ? Will P-Delta analysis take care of this ?
thanks and regrds
meera p



On Mon, Nov 19, 2012 at 11:00 AM, Econf_Moderator forum@sefindia.org (forum@sefindia.org))> wrote:
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PostPosted: Thu Nov 22, 2012 5:56 pm    Post subject: Welcome to the Econference on Design and Construction of Tal Reply with quote

Mr. V.P.Agarwal has raised a very vital issue which is faced by all engineers in private consulting companies in this country.

Due to highly competitive scenario of too many consulting companies vis-a-vis too less job orders carrying little fees, most organisations are working with skeletal strength, least holidays to their employee and  bare minimum salaries. Result? Nobody knows whether your colleague or the CAD operator working with you shall come tomorrow.


A dedicated and experienced engineer is required to handle the software for analyzing and designing a multi-storied building with undisturbed attention which most private companies can ill-afford. He is often called for discussions, for solving problems arising in the earlier assignments where constructions have already started or for finalisation of next assignment.So mistakes can occur and may remain undetected. I doubt whether, in such scenarios any second engineer is available for complete checking of directories of his colleague, because his situation is also no better.While reading a Design report of a job in Sharjah, I noticed a declaration that " another engineer has checked the design".Is such practice followed in India? 


Dipak Bhattacharya / Delhi. 


On 19 November 2012 17:00, ishacon <forum@sefindia.org (forum@sefindia.org)> wrote:
Quote:
           Dear All,

It is indeed very heartening to see that this Econf has kicked off with
Welcome Notes from eminent engineers and Professors.
Permit me to voice some of my concerns in general.

Having been involved in Design audits of several tall buildings ( 75 meter height and above),
in NCR region during last more than a decade, I have seen at close quarters the dire
need of improvement in preparation of the drawings and careful checking thereof.
Shortage of trained manpower for checking and the copy, paste routines of CAD by the draftsmen
leave many errors untraced.
This practice needs to be stopped at the consultant's end.

Due to the urgencies imposed by the Builder / developer, often the Structural Consultant
is compelled to perform the analysis based on half baked inputs from the Architect and he
has to issue foundation drawings with column schedules without having gone through detailed
investigations on analysis front since the excavation is already done. Often the soil investigation reports
do not do full justice to the testing and making appropriate recommnedations.
It is about time, that everyone in the industry recognise the perils of doing so.

V.P. Agarwal
B.Tech (IITMadras), M.Engg (USA)

ISHA CONSULTANTS (P) LTD
NEW DELHI 110074

PH : 011-2630 1158 ;
08010071749 ; 093 1345 2180
      :                 -- Original Message --
From: prasadam_iitm (forum@sefindia.org (forum@sefindia.org))
To: econf34289@sefindia.org (econf34289@sefindia.org) (econf34289@sefindia.org (econf34289@sefindia.org))
Sent: Monday, November 19, 2012 3:00 PM
Subject: [E-CONF] Re: Welcome to the Econference on Design and Construction of Tal


On 19-Nov-2012, at 11:00 AM, Econf_Moderator wrote:
: Dear All:


Greetings and welcome to the E-conference on Design and Construction of Tall Buildings in India. As has been mentioned earlier the conference will run Nov. 19 through Nov 28.


A few pointers on Econference protocol.



* All topics pertaining to Tall Buildings may be discussed and we will urge all of you to participate in adding value to a topic with informed and well-thought out comments so as to maintain the standard of the Econference to international quality. We request that you please keep your subject note or comment on an issue crisp and topical.


* Any issues which are not core to the technical part of the Econference may please be discussed on the SpeakOut forum, not in the Econference, please.


* Kindly limit discussions to max of two issues pertaining to tall buildings in a single mail. The issues should be in different paragraphs. Also, when differing with another commentator, pl exercise utmost civility while expressing your disagreement.


We had suggested some topics for discussion and we had received valuable input from all of you. We have incorporated your suggestions and produced a revised list as under. This is not an exhaustive list and other pertinent technical issues can be added as required.


We have a list of subject experts for the Econference. We will introduce them along the way. We look forward to some exciting days ahead.....


warm regards,


Alpa Sheth
Prof CVR Murry
Prof Swaminathan Krishnan


Econference Moderators


******




Topics for Tall Buildings Conference

What do we define as a tall building?

a) Siting of tall buildings:
i Where are tall buildings allowed/not allowed to be sited?
b) Geotechnical Issues
  • Soil Testing for Tall Buildings.
  • Testing for establishing soil and pile modulus

c) General Parameters of Tall Buildings
  • Geometric Proportioning
  • Height and Aspect Ratio
  • General Distribution and area of Vertical and Lateral load carrying elements as % of plan area for concrete and steel structures.
  • Min required stiffness of building  
  • Perimeter offset to avoid pounding
d) Structural Configuration, Structural Systems and their Behaviour
  • Selection of Structural system- Preliminary behavior analysis of alternative systems
  • Discussion of Strucutral Sustems- Frames, Shear Walls, Frame-Shear Walls, Slab-Column Shear Wall structure, Tube Stucture, Hybrid Structure.....  
  • Performance of different structural systems;
  • What levels of ductility are achievable in the lateral force resisting systems being constructed in India? What should the value of R be?
  • Hybrid Structural Systems and their behaviour  
  • Achieving redundancy and alternative load path

d) Load Combinations

e) Use of Masonry partition walls in tall buildings
  • Should they be included in analysis?
  • Should they be isolated from structure or not?
  • Any special specifications for partition walls of tall buildings? (Light weight etc.)


f) Modeling and Analysis
  • Appropriate Modelling tools and soft ware for elastic, inelastic design for different systems and elements


g) Structural Irregularities
  • Should structural system transfer be allowed in tall buildings? If yes what are the limitations to be observed?
  • Soft storey, Weak Storey
  • How to deal with torsional irregularity? How much max modal mass may be excited in torsional modes of vibration?  

h) Wind Design
  • When should Wind Tunnel Testing be carried out?
  • What are the wind tunnel tests that should be carried out and to what effect? How to account for future buildings in the neighborhood in the layout and configurtion of adjacent buildings in the wind tunnel?  
  • What are the results to be asked from the WT testing agency?
  • Appropriate Damping Values
  • Discussion on Wind Dampers- When to use them, What type to use for what building application?
  • Should there be instrumentation on tall buildings for measurement of vibrations/accelerations?  


i) Earthquake Analysis and Design
  • Does the current IS 1893 assure acceptable performance of tall buildings?
  • Seismic hazard characterization (base shear, response spectrum, ground motion histories, near-source effects, fault maps, fault classification w.r.t. earthquake potential characterization).  
  • Site soil characterization.
  • Closely spaced modes-How critical is this issue?
  • Linear static analysis procedure.
  • Dynamic response spectrum procedure. What should the spectrum look like? When should a site-specific spectrum be required? How to account for near-source effects (applies to linear static procedure as well)?  
  • When should one do non-linear analysis? What are the earthquake ground motions to be considered in Indian scenario?
  • How to properly account for P-Delta effects (modeling gravity columns)? Do we have software for nonlinear analysis readily available? Are test data characterizing component nonlinear (cyclic) behavior using prevailing Indian standards of practice available? What should the material models look like for various structural components?  
  • When is a pushover analysis required?


j) Frame Structure -Ductile detailing criteria:

  • · What criteria and when applicable?
  • · Strong-column weak beam in moment frames
  • · boundary elements in shear walls
  • · tie-spacing
  • · 135 degree hooks
  • · lap-splices and development length  
  • · location of splices
  • · beam-column joint detailing in concrete frames
  • · continuity of column vertical rebar and beam longitudinal rebar through the joint
  • · link beam detailing (diagonal rebar)  
  • · required level of diaphragm attachment on either side of a given length of wall, etc.
  • · When and where is Capacity Design required?
  • Column (gravity/lateral) design (include long-term axial shortening of columns due to creep and its effects on beams/floor slabs, etc.);  
  • Use of composite sections for creep control.


k) Shear Wall


  • Wall design (include long-term axial shortening due to creep)
  • Link beam design
  • Diaphragm design
l) Energy dissipation devices
  • viscous fluid dampers
  • added stiffness and damping devices

m) Use of Precast in Tall Building Construction
  • Should it be permitted?
  • To be used for which elements of structure?
  • Design and detailing of joints?
  • Behaviour in past earthquakes
n) Foundations
a. Discussion on Piled raft foundations
· Allowable deformations
· Pile-raft interaction
· Analysis of piled rafts
. Shoring for Deep Basements
· Pile testing for deep piles
· Max allowable deformation of piles of piled raft- codal provisions?
· Deformations in piled raft?
· Differential settlement between core and perimeter. Provide a pour strip to minimize such settlement (when to provide). Additional moments in beams and slab due to such differential settlement.
· Design methodology and detailing of piles and rafts; lateral shear capacity of piles, vertical load carrying capacity of piles (skin friction vs bearing).
b. Raft foundations for tall buildings
c. Pile foundations for Tall buildings



o) Facades
  • Stiffness
  • Isolation; Designing the façade system to permit movement corresponding to wind and seismic drift limits.


p) Tall Building with Podium issues
  • Should tower be connected to Podium? When?
  • Should Basement walls be considered in Analysis?
  • Any special considerations to cater for large shear transfer in the podium diaphragm from tower? (refer ATC)  
q) Performance Criteria
  • Serviceability Requirements
  • What should be the limiting acceleration values for human comfort level in wind design?
  • What is max drift to be allowed in wind and earthquake? What can be the sudden spike in interstorey drift due to a soft/weak storey?  
r) Performance Based (Seismic) Design of Structures
  • When to do this?
  • How to do it?
  • Review Procedures ....
s) Other Detailing Aspects of Tall Buildings
  • Detailing of cold joints (Core and floor slab done separately)
  • Dealing with congestion of steel
  • Splices/Anchorages
  • Expansion Joint issues
  • Seismic joints: When to use and how to design.  
  • Design of Inclines Columns, Bracings etc.

t) Construction Issues of Tall Buildings
  • Modular/Lightweight shuttering
  • Slipform Shuttering
  • High strength concretes – Issues of microcracking, delayed strength, additives, flyash, silica fumes etc.
  • High Grade Steel- Inconsistency in yield stress.  
  • Dealing with congestion of steel in beam-column joints
  • Vertical Transportation of concrete
  • Durability of Tall Buildings- How to repair/retrofit?
  • Concrete grade of columns vs. concrete grade of slabs – How to deal with difference?  
u) Construction Specifications
  • Materials (including welds, rebar, concrete, structural steel, etc.)
  • Structural, Mechanical, Electrical, Plumbing, Vertical Transportation systems
  • Site preparation and managementa


v) Green Building Issues

***










Meher Prasad Anumolu
Professor, Department of Civil Engineering
IIT Madras
prasadam@iitm.ac.in (prasadam@iitm.ac.in) (prasadam@iitm.ac.in (prasadam@iitm.ac.in)) (prasadam@iitm.ac.in (prasadam@iitm.ac.in) (prasadam@iitm.ac.in (prasadam@iitm.ac.in)))





     
     



     



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