STRUCTURAL ENGINEERING FORUM OF INDIA [SEFI]

alpa_sheth · ... Joined: 26 Jan 2003 Posts: 278

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.�

我们有一个系统t 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?

一)��高层建筑的选址:��
� � � 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?�
�任何特殊规格分区的墙壁�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
对桩筏��分析
. � 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 fa�ade 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�

Posted via Email

Econf_Moderator · E-Conference Moderator Joined: 26 Feb 2012 Posts: 23

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.�

我们有一个系统t 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?

一)��高层建筑的选址:��
� � � 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?�
�任何特殊规格分区的墙壁�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
对桩筏��分析
. � 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 fa�ade 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�

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

Posted via Email

napeera · SEFI Member Joined: 02 Jul 2010 Posts: 10

Dear all,It is my privilege to be a member of this very highly professional and knowledgeable forum from which I have benefited a lot. 5 stars from me for starting this very informative E-Conference, which will help immensely, the structural engineers who must have just started designing tall structures.My first question will be. What is the definition of Tall Building in detail?Regards & best of luck. NAPeera - from Vodafone
From:"alpa_sheth"
Date:Mon, 19 Nov 2012 09:00:03 +0530
To:
ReplyTo:econf34289@www.bussiapp.com
Subject:[E-CONF] Welcome to the Econference on Design and Construction of Tall bUildings

亲爱的所有:�E-conferen问候和欢迎ce 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?�
�任何特殊规格分区的墙壁�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 fa�ade 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� --

Posted via Email

dssri · SEFI Member Joined: 26 Jan 2003 Posts: 5

1. How do we define a tall building - absolute height, aspect ratio, method of construction or the sesimic zone it is situated
2.着手一幢高楼——一个ny regulation needed to restrict the construction of tall buildings only to builder/developer/contractor having prior experience

god bless
D S SRIDHAR
ME, FIE, FIV, AMP (IIM)
G 908 Mantri Tranquil
Sy. No. 7/9/13 Gubalala
Kanakapura Road
BANGALORE 560061
KARNATAKA INDIA
CELL +91-9845094486
dssri64@gmail.com (dssri64@gmail.com)
sridhar.ds@alumni.iimb.ernet.in (sridhar.ds@alumni.iimb.ernet.in)

Engineer · SEFI Member Joined: 28 Jun 2010 Posts: 10

I have attached herewith draft document prepared by CTBHU Committee on Seismic Design of Tall Buildingswww.ctbhu.org

Regards,
Hemant Gor

Posted via Email

prasadam_iitm · SEFI Member Joined: 16 Nov 2012 Posts: 2

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

drferozkottamal · SEFI Member Joined: 29 Jan 2012 Posts: 7

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

On 19 November 2012 06:30, alpa_sheth forum@www.bussiapp.com)> wrote:

ishacon · Silver Sponsor Joined: 01 Apr 2008 Posts: 148

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

BJREDDY · SEFI Member Joined: 17 Nov 2011 Posts: 1

Dear All

My best wishes to SEFI organizers for creating this excellent platform for sharing knowledge about tall buildings. I am much excited and enthusiastic to participate in this E-conference.
I would like to share this document prepared by CTBUH, which will basically explain
"Criteria for the Defining and Measuring of Tall Buildings".

Thanks & Regards,
BJReddy

partha at adaptsoft.com · Guest

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@www.bussiapp.com)
Sent:Monday, November 19, 2012 11:00 AM
To:econf34289@www.bussiapp.com(econf34289@www.bussiapp.com)
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.

我们有一个系统t 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

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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

土壤测试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?

我)地震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长度和发展
� 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
桩基础Tall buildings

o) Facades

Stiffness
Isolation; Designing the fa�ade 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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