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Comparing Tall Building Design China vs India - Part I

 
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alpa_sheth
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Joined: 26 Jan 2003
Posts: 253
Location: Mumbai

PostPosted: Fri Nov 23, 2012 7:48 am    Post subject: Comparing Tall Building Design China vs India - Part I Reply with quote

Dear All:


Consequent to my mail requesting more participation from all, there has been such a flurry of activity Smile, it is hard to keep up with the discussions on multiple topics of Tall buildings.
I am going to try to discuss one new  topic re. tall buildings – a comparison of the way the Chinese code look at tall building design vs. what we have in India (and a bit in the ASCE codes as discussed by Prof Swami and Ms. Anjana Kadakia) and along the way I think many of the issues/queries raised will receive  an alternative opinion
I make special mention of the China code JGJ-3 “Technical Specification for Concrete Structures of Tall Buildings” as no other code in the world, IMHO has as detailed prescriptive  requirements for tall buildings. I will not refer to Steel buildings herein which have a separate high rise code in China .  what the prescriptive measures are, I will highlight herein soon enough, but first let me discuss what happens to projects which do not follow the parameters given in this code or what are called “Code-Exceeding Buildings”
For  Code- Exceeding Buildings  in China, there is a very detailed Engineering Panel Review carried out for  the Building Administration Authority by a Panel comprising  several (more than 5) experts to review the design;  These experts are part of the larger National Panel (current panel of national experts has  44 regular members and 8 advisory members comprising of  eminent members selected from academia and practice).  They may Pass, Fail or Send the Building for Redesign/Revaluation after detailed discussions with the design team and client. The genesis of the panel formation was a document “Provisions on Administration of Seismic Fortification of Code-exceeding High-rise Buildings” .  The main objective of the process is in some ways to “punish” if I may, such code exceeding buildings by requiring them to be designed for enhanced performance objectives over and above the prescriptive code and identifying key areas of weakness which make them “deviants” of the prescriptive code and additionally strengthen them, beyond prescriptive code requirements so that they no longer are the “weak links”.  The idea is to  ensure much more  structural safety, redundancy, and structural efficiency for a limited cost.  The system depends heavily on “structural wisdom” of experts.  You can read more on this in a paper “APPROVAL PROCESSES FOR THE DESIGN OF TALL, NON-PRESCRIPTIVE STRUCTURES” Mark Sarkisian, Neville Mathias  and Zhao-fan Li published/to be published  in IABSE .

Okay now going back to the prescriptive code and I am interpreting the Chinese Code (the part I had access to) to respond to many queries on typical Issues being discussed in the econference.  (China is divided into 5 seismic zones varying from Intensity 6 to 9 corresponding to    PGA 0.05g to 0.4g respectively in a 10% in 50 year event.

a)      What are the height limitations of the structural systems that may be used in each zone?
Allowable height in m. for regular buildings (roughly equiv to Importance factor of 1.0 for us)

System

Seismic Intensity 6

Seismic Intensity 7 (~ IS Zone III)

Seismic Intensity 8 (~  Zone IV)

Seismic Intensity 9
(Zone V)

Frame Only

60

50

40

NA

Frame -Shear Wall

160

140

120

100

Shear wall only (going up to ground)

170

150

130

110

(Flat) Slab-column Shear wall

80

70

55

NA

Tube with frame-corewall/Tube in tube

210/280

180/230

140/170

120/150

I have simplified it a bit, pl note.  But no such restriction in IS code


b)      What are allowable inter-story deflections?

L/550 for frame structure, L/800 for frame shear wall, frame –core wall and (flat) slab- column shear wall, L/1000 for shear wall only and tune-in-tube, L/1000 for transfer story (L=ht)- (Sangeeta Wij  had asked re. transfer floors. I hope this and the requirements for code-exceeding buildings responds partially to her query. )


The requirements are same for wind as well as standard value frequent earthquakes.

Compare this with IS Code L/500 for all structural systems for wind design and L/250 for earthquake design. (Not discussing allowable  interstory elasto-plastic displacement angle presently)


c)       What is the max allowable Aspect Ratio of a Building ?
It varies based on structural system selected and the Seismic Zone. Max allowable aspect ratio is 8 for Intensity 6/7 regions with Tube-in-tube system and max aspect ratio is 3 for a frame wall system in Intensity 8. No such restriction in IS code


d)      What is the max width to Length ratio in plan?
For intensity 6/7, length cannot be more than 6 time breadth for rectangular buildings. No such restriction in IS code


e)      What is  the max area of openings in a floor slab?
30% of floor area. No such restriction in IS code


f)       What is the max wind vibration acceleration permitted ?
Residential 0.15 m/s2, Office 0.25 m/s2. No such restriction in IS code


g)      How do you account for non-bearing masonry walls in stiffness calculations?
The Chinese code does not have empirical Time period formulae as in IS code. However it says that the stiffness of these walls may be accounted by factoring the Time period calculated through analysis by a reduction coefficient equal to 0.6~0.7 for frame buildings, 0.7~0.8 for frame-shear wall buildings, 08~1.0 for shearwall buildings.


I think this is a long enough mail for now.


Thanks and best regards,


Alpa Sheth
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mehtavin
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Joined: 07 May 2009
Posts: 28

PostPosted: Fri Nov 23, 2012 8:58 am    Post subject: Comparing Tall Building Design China vs India - Part I Reply with quote

For all Sefians and this conference specifically, a very interesting news and methodology for Tall Buildings in China
China Will Build the Tallest Building In the World in Just 90 Days  

http://gizmodo.com/5962070/china-will-build-the-tallest-building-in-the-world-in-just-90-days


Regards,

Vinay Mehta


From: alpa_sheth [mailto:forum@sefindia.org]
Sent: Friday, November 23, 2012 2:23 PM
To: econf34289@sefindia.org
Subject: [SPAM]- [E-CONF] Comapring Tall Building Design China vs India - Part I  



Dear All:


Consequent to my mail requesting more participation from all, there has been such a flurry of activity Smile, it is hard to keep up with the discussions on multiple topics of Tall buildings.
I am going to try to discuss one new topic re. tall buildings – a comparison of the way the Chinese code look at tall building design vs. what we have in India (and a bit in the ASCE codes as discussed by Prof Swami and Ms. Anjana Kadakia) and along the way I think many of the issues/queries raised will receive an alternative opinion
I make special mention of the China code JGJ-3 “Technical Specification for Concrete Structures of Tall Buildings” as no other code in the world, IMHO has as detailed prescriptive requirements for tall buildings. I will not refer to Steel buildings herein which have a separate high rise code in China . what the prescriptive measures are, I will highlight herein soon enough, but first let me discuss what happens to projects which do not follow the parameters given in this code or what are called “Code-Exceeding Buildings”
For Code- Exceeding Buildings in China, there is a very detailed Engineering Panel Review carried out for the Building Administration Authority by a Panel comprising several (more than 5) experts to review the design; These experts are part of the larger National Panel (current panel of national experts has 44 regular members and 8 advisory members comprising of eminent members selected from academia and practice). They may Pass, Fail or Send the Building for Redesign/Revaluation after detailed discussions with the design team and client. The genesis of the panel formation was a document “Provisions on Administration of Seismic Fortification of Code-exceeding High-rise Buildings” . The main objective of the process is in some ways to “punish” if I may, such code exceeding buildings by requiring them to be designed for enhanced performance objectives over and above the prescriptive code and identifying key areas of weakness which make them “deviants” of the prescriptive code and additionally strengthen them, beyond prescriptive code requirements so that they no longer are the “weak links”. The idea is to ensure much more structural safety, redundancy, and structural efficiency for a limited cost. The system depends heavily on “structural wisdom” of experts. You can read more on this in a paper “APPROVAL PROCESSES FOR THE DESIGN OF TALL, NON-PRESCRIPTIVE STRUCTURES” Mark Sarkisian, Neville Mathias and Zhao-fan Li published/to be published in IABSE .

Okay now going back to the prescriptive code and I am interpreting the Chinese Code (the part I had access to) to respond to many queries on typical Issues being discussed in the econference. (China is divided into 5 seismic zones varying from Intensity 6 to 9 corresponding to PGA 0.05g to 0.4g respectively in a 10% in 50 year event.

a) What are the height limitations of the structural systems that may be used in each zone?
Allowable height in m. for regular buildings (roughly equiv to Importance factor of 1.0 for us)
System
Seismic Intensity 6
Seismic Intensity 7 (~ IS Zone III)
Seismic Intensity 8 (~ Zone IV)
Seismic Intensity 9
(Zone V)
Frame Only
60
50
40
NA
Frame -Shear Wall
160
140
120
100
Shear wall only (going up to ground)
170
150
130
110
(Flat) Slab-column Shear wall
80
70
55
NA
Tube with frame-corewall/Tube in tube
210/280
180/230
140/170
120/150

I have simplified it a bit, pl note. But no such restriction in IS code

b) What are allowable inter-story deflections?

L/550 for frame structure, L/800 for frame shear wall, frame –core wall and (flat) slab- column shear wall, L/1000 for shear wall only and tune-in-tube, L/1000 for transfer story (L=ht)- (Sangeeta Wij had asked re. transfer floors. I hope this and the requirements for code-exceeding buildings responds partially to her query. )

The requirements are same for wind as well as standard value frequent earthquakes.
Compare this with IS Code L/500 for all structural systems for wind design and L/250 for earthquake design. (Not discussing allowable interstory elasto-plastic displacement angle presently)

c) What is the max allowable Aspect Ratio of a Building ?
It varies based on structural system selected and the Seismic Zone. Max allowable aspect ratio is 8 for Intensity 6/7 regions with Tube-in-tube system and max aspect ratio is 3 for a frame wall system in Intensity 8. No such restriction in IS code

d) What is the max width to Length ratio in plan?
For intensity 6/7, length cannot be more than 6 time breadth for rectangular buildings. No such restriction in IS code

e) What is the max area of openings in a floor slab?
30% of floor area. No such restriction in IS code

f) What is the max wind vibration acceleration permitted ?
Residential 0.15 m/s2, Office 0.25 m/s2. No such restriction in IS code

g) How do you account for non-bearing masonry walls in stiffness calculations?
The Chinese code does not have empirical Time period formulae as in IS code. However it says that the stiffness of these walls may be accounted by factoring the Time period calculated through analysis by a reduction coefficient equal to 0.6~0.7 for frame buildings, 0.7~0.8 for frame-shear wall buildings, 08~1.0 for shearwall buildings.

I think this is a long enough mail for now.

Thanks and best regards,

Alpa Sheth

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ishacon
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Joined: 01 Apr 2008
Posts: 148

PostPosted: Fri Nov 23, 2012 10:15 am    Post subject: Comapring Tall Building Design China vs India - Part I Reply with quote

Absolutely fantastic information as a digest of Chinese code.
No wonder the people there respect the rule of law
and follow the stringent requirements, spelled out unlike the Indian Codes, which have loop holes, similar to the Laws of our country.

VP Agarwal
ISHA CONSULTANTS (P) LTD
NEW DELHI 110074

PH : 011-2630 1158 ;
08010071749 ; 093 1345 2180
Quote:
-- Original Message --
From: alpa_sheth (forum@sefindia.org)
To: econf34289@sefindia.org (econf34289@sefindia.org)
Sent: Friday, November 23, 2012 2:23 PM
Subject: [E-CONF] Comapring Tall Building Design China vs India - Part I


Dear All:


Consequent to my mail requesting more participation from all, there has been such a flurry of activity Smile, it is hard to keep up with the discussions on multiple topics of Tall buildings.
I am going to try to discuss one new topic re. tall buildings – a comparison of the way the Chinese code look at tall building design vs. what we have in India (and a bit in the ASCE codes as discussed by Prof Swami and Ms. Anjana Kadakia) and along the way I think many of the issues/queries raised will receive an alternative opinion
I make special mention of the China code JGJ-3 “Technical Specification for Concrete Structures of Tall Buildings” as no other code in the world, IMHO has as detailed prescriptive requirements for tall buildings. I will not refer to Steel buildings herein which have a separate high rise code in China . what the prescriptive measures are, I will highlight herein soon enough, but first let me discuss what happens to projects which do not follow the parameters given in this code or what are called “Code-Exceeding Buildings”
For Code- Exceeding Buildings in China, there is a very detailed Engineering Panel Review carried out for the Building Administration Authority by a Panel comprising several (more than 5) experts to review the design; These experts are part of the larger National Panel (current panel of national experts has 44 regular members and 8 advisory members comprising of eminent members selected from academia and practice). They may Pass, Fail or Send the Building for Redesign/Revaluation after detailed discussions with the design team and client. The genesis of the panel formation was a document “Provisions on Administration of Seismic Fortification of Code-exceeding High-rise Buildings” . The main objective of the process is in some ways to “punish” if I may, such code exceeding buildings by requiring them to be designed for enhanced performance objectives over and above the prescriptive code and identifying key areas of weakness which make them “deviants” of the prescriptive code and additionally strengthen them, beyond prescriptive code requirements so that they no longer are the “weak links”. The idea is to ensure much more structural safety, redundancy, and structural efficiency for a limited cost. The system depends heavily on “structural wisdom” of experts. You can read more on this in a paper “APPROVAL PROCESSES FOR THE DESIGN OF TALL, NON-PRESCRIPTIVE STRUCTURES” Mark Sarkisian, Neville Mathias and Zhao-fan Li published/to be published in IABSE .

Okay now going back to the prescriptive code and I am interpreting the Chinese Code (the part I had access to) to respond to many queries on typical Issues being discussed in the econference. (China is divided into 5 seismic zones varying from Intensity 6 to 9 corresponding to PGA 0.05g to 0.4g respectively in a 10% in 50 year event.

<![if !supportLists]>a)<![endif]> What are the height limitations of the structural systems that may be used in each zone?
Allowable height in m. for regular buildings (roughly equiv to Importance factor of 1.0 for us)
System
Seismic Intensity 6
Seismic Intensity 7 (~ IS Zone III)
Seismic Intensity 8 (~ Zone IV)
Seismic Intensity 9
(Zone V)
Frame Only
60
50
40
NA
Frame -Shear Wall
160
140
120
100
Shear wall only (going up to ground)
170
150
130
110
(Flat) Slab-column Shear wall
80
70
55
NA
Tube with frame-corewall/Tube in tube
210/280
180/230
140/170
120/150

I have simplified it a bit, pl note. But no such restriction in IS code

<![if !supportLists]>b)<![endif]> What are allowable inter-story deflections?

L/550 for frame structure, L/800 for frame shear wall, frame –core wall and (flat) slab- column shear wall, L/1000 for shear wall only and tune-in-tube, L/1000 for transfer story (L=ht)- (Sangeeta Wij had asked re. transfer floors. I hope this and the requirements for code-exceeding buildings responds partially to her query. )

The requirements are same for wind as well as standard value frequent earthquakes.
Compare this with IS Code L/500 for all structural systems for wind design and L/250 for earthquake design. (Not discussing allowable interstory elasto-plastic displacement angle presently)

<![if !supportLists]>c)<![endif]> What is the max allowable Aspect Ratio of a Building ?
It varies based on structural system selected and the Seismic Zone. Max allowable aspect ratio is 8 for Intensity 6/7 regions with Tube-in-tube system and max aspect ratio is 3 for a frame wall system in Intensity 8. No such restriction in IS code

<![if !supportLists]>d)<![endif]> What is the max width to Length ratio in plan?
For intensity 6/7, length cannot be more than 6 time breadth for rectangular buildings. No such restriction in IS code

<![if !supportLists]>e)<![endif]> What is the max area of openings in a floor slab?
30% of floor area. No such restriction in IS code

<![if !supportLists]>f)<![endif]> What is the max wind vibration acceleration permitted ?
Residential 0.15 m/s2, Office 0.25 m/s2. No such restriction in IS code

<![if !supportLists]>g)<![endif]> How do you account for non-bearing masonry walls in stiffness calculations?
The Chinese code does not have empirical Time period formulae as in IS code. However it says that the stiffness of these walls may be accounted by factoring the Time period calculated through analysis by a reduction coefficient equal to 0.6~0.7 for frame buildings, 0.7~0.8 for frame-shear wall buildings, 08~1.0 for shearwall buildings.

I think this is a long enough mail for now.

Thanks and best regards,

Alpa Sheth







Posted via Email
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Dr. N. Subramanian
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Joined: 21 Feb 2008
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PostPosted: Fri Nov 23, 2012 4:11 pm    Post subject: Re: Comapring Tall Building Design China vs India - Part I Reply with quote

Dear Er Agarwal,

Please see the posting on a similar precast prefab building in China by me and the comments by Dr Swaminathan, the Moderator of this conf.

http://www.sefindia.org/forum/viewtopic.php?t=12920
Also see the note on two tall buildings in China
http://www.sefindia.org/forum/viewtopic.php?t=13167
http://www.sefindia.org/forum/viewtopic.php?t=13164

Regards,
NS

quote="ishacon"]Absolutely fantastic information as a digest of Chinese code.
No wonder the people there respect the rule of law
and follow the stringent requirements, spelled out unlike the Indian Codes, which have loop holes, similar to the Laws of our country.

VP Agarwal
ISHA CONSULTANTS (P) LTD
NEW DELHI 110074

PH : 011-2630 1158 ;
08010071749 ; 093 1345 2180
Quote:
-- Original Message --
From: alpa_sheth (forum@sefindia.org)
To: econf34289@sefindia.org (econf34289@sefindia.org)
Sent: Friday, November 23, 2012 2:23 PM
Subject: [E-CONF] Comapring Tall Building Design China vs India - Part I


Dear All:


Consequent to my mail requesting more participation from all, there has been such a flurry of activity Smile, it is hard to keep up with the discussions on multiple topics of Tall buildings.
I am going to try to discuss one new topic re. tall buildings – a comparison of the way the Chinese code look at tall building design vs. what we have in India (and a bit in the ASCE codes as discussed by Prof Swami and Ms. Anjana Kadakia) and along the way I think many of the issues/queries raised will receive an alternative opinion
I make special mention of the China code JGJ-3 “Technical Specification for Concrete Structures of Tall Buildings” as no other code in the world, IMHO has as detailed prescriptive requirements for tall buildings. I will not refer to Steel buildings herein which have a separate high rise code in China . what the prescriptive measures are, I will highlight herein soon enough, but first let me discuss what happens to projects which do not follow the parameters given in this code or what are called “Code-Exceeding Buildings”
For Code- Exceeding Buildings in China, there is a very detailed Engineering Panel Review carried out for the Building Administration Authority by a Panel comprising several (more than 5) experts to review the design; These experts are part of the larger National Panel (current panel of national experts has 44 regular members and 8 advisory members comprising of eminent members selected from academia and practice). They may Pass, Fail or Send the Building for Redesign/Revaluation after detailed discussions with the design team and client. The genesis of the panel formation was a document “Provisions on Administration of Seismic Fortification of Code-exceeding High-rise Buildings” . The main objective of the process is in some ways to “punish” if I may, such code exceeding buildings by requiring them to be designed for enhanced performance objectives over and above the prescriptive code and identifying key areas of weakness which make them “deviants” of the prescriptive code and additionally strengthen them, beyond prescriptive code requirements so that they no longer are the “weak links”. The idea is to ensure much more structural safety, redundancy, and structural efficiency for a limited cost. The system depends heavily on “structural wisdom” of experts. You can read more on this in a paper “APPROVAL PROCESSES FOR THE DESIGN OF TALL, NON-PRESCRIPTIVE STRUCTURES” Mark Sarkisian, Neville Mathias and Zhao-fan Li published/to be published in IABSE .

Okay now going back to the prescriptive code and I am interpreting the Chinese Code (the part I had access to) to respond to many queries on typical Issues being discussed in the econference. (China is divided into 5 seismic zones varying from Intensity 6 to 9 corresponding to PGA 0.05g to 0.4g respectively in a 10% in 50 year event.

<if>a)<endif> What are the height limitations of the structural systems that may be used in each zone?
Allowable height in m. for regular buildings (roughly equiv to Importance factor of 1.0 for us)
System
Seismic Intensity 6
Seismic Intensity 7 (~ IS Zone III)
Seismic Intensity 8 (~ Zone IV)
Seismic Intensity 9
(Zone V)
Frame Only
60
50
40
NA
Frame -Shear Wall
160
140
120
100
Shear wall only (going up to ground)
170
150
130
110
(Flat) Slab-column Shear wall
80
70
55
NA
Tube with frame-corewall/Tube in tube
210/280
180/230
140/170
120/150

I have simplified it a bit, pl note. But no such restriction in IS code

<if>b)<endif> What are allowable inter-story deflections?

L/550 for frame structure, L/800 for frame shear wall, frame –core wall and (flat) slab- column shear wall, L/1000 for shear wall only and tune-in-tube, L/1000 for transfer story (L=ht)- (Sangeeta Wij had asked re. transfer floors. I hope this and the requirements for code-exceeding buildings responds partially to her query. )

The requirements are same for wind as well as standard value frequent earthquakes.
Compare this with IS Code L/500 for all structural systems for wind design and L/250 for earthquake design. (Not discussing allowable interstory elasto-plastic displacement angle presently)

<if>c)<endif> What is the max allowable Aspect Ratio of a Building ?
It varies based on structural system selected and the Seismic Zone. Max allowable aspect ratio is 8 for Intensity 6/7 regions with Tube-in-tube system and max aspect ratio is 3 for a frame wall system in Intensity 8. No such restriction in IS code

<if>d)<endif> What is the max width to Length ratio in plan?
For intensity 6/7, length cannot be more than 6 time breadth for rectangular buildings. No such restriction in IS code

<if>e)<endif> What is the max area of openings in a floor slab?
30% of floor area. No such restriction in IS code

<if>f)<endif> What is the max wind vibration acceleration permitted ?
Residential 0.15 m/s2, Office 0.25 m/s2. No such restriction in IS code

<if>g)<endif> How do you account for non-bearing masonry walls in stiffness calculations?
The Chinese code does not have empirical Time period formulae as in IS code. However it says that the stiffness of these walls may be accounted by factoring the Time period calculated through analysis by a reduction coefficient equal to 0.6~0.7 for frame buildings, 0.7~0.8 for frame-shear wall buildings, 08~1.0 for shearwall buildings.

I think this is a long enough mail for now.

Thanks and best regards,

Alpa Sheth







Posted via Email[/quote]
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biju
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Joined: 26 Jan 2003
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PostPosted: Mon Nov 26, 2012 9:02 am    Post subject: Reply with quote

Dear madam,

Pls. check the acceleration values.

It can be 10 to 25 milli g, ie 0.01 to 0.025 m/s2.

regards,

Biju
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PostPosted: Wed Nov 28, 2012 4:59 am    Post subject: Re: Comparing Tall Building Design China vs India - Part I Reply with quote

Dear Er Alpa,

Glad to note that china has a separate code on Tall buildings for Concrete as well as Steel. Unless India also has a special code, it can not cover all the aspects of Tall Buildings in a single code. Note that BIS has separate codes on Precast structures, shell structures, etc. In concrete alone it has about 80 codes.

It reminds me that China also has a separate code on Space Structures! When I proposed a similar code, by sending a copy of the same to BIS- I even attended the committee meeting. But a professor, known to me, put spokes into the proposal and stalled the code.

Please provide the link to the paper mentioned by you.

Regards,
Subramanian

alpa_sheth wrote:
Dear All:


Consequent to my mail requesting more participation from all, there has been such a flurry of activity Smile, it is hard to keep up with the discussions on multiple topics of Tall buildings.
I am going to try to discuss one new  topic re. tall buildings – a comparison of the way the Chinese code look at tall building design vs. what we have in India (and a bit in the ASCE codes as discussed by Prof Swami and Ms. Anjana Kadakia) and along the way I think many of the issues/queries raised will receive  an alternative opinion
I make special mention of the China code JGJ-3 “Technical Specification for Concrete Structures of Tall Buildings” as no other code in the world, IMHO has as detailed prescriptive  requirements for tall buildings. I will not refer to Steel buildings herein which have a separate high rise code in China .  what the prescriptive measures are, I will highlight herein soon enough, but first let me discuss what happens to projects which do not follow the parameters given in this code or what are called “Code-Exceeding Buildings”
For  Code- Exceeding Buildings  in China, there is a very detailed Engineering Panel Review carried out for  the Building Administration Authority by a Panel comprising  several (more than 5) experts to review the design;  These experts are part of the larger National Panel (current panel of national experts has  44 regular members and 8 advisory members comprising of  eminent members selected from academia and practice).  They may Pass, Fail or Send the Building for Redesign/Revaluation after detailed discussions with the design team and client. The genesis of the panel formation was a document “Provisions on Administration of Seismic Fortification of Code-exceeding High-rise Buildings” .  The main objective of the process is in some ways to “punish” if I may, such code exceeding buildings by requiring them to be designed for enhanced performance objectives over and above the prescriptive code and identifying key areas of weakness which make them “deviants” of the prescriptive code and additionally strengthen them, beyond prescriptive code requirements so that they no longer are the “weak links”.  The idea is to  ensure much more  structural safety, redundancy, and structural efficiency for a limited cost.  The system depends heavily on “structural wisdom” of experts.  You can read more on this in a paper “APPROVAL PROCESSES FOR THE DESIGN OF TALL, NON-PRESCRIPTIVE STRUCTURES” Mark Sarkisian, Neville Mathias  and Zhao-fan Li published/to be published  in IABSE .

Okay now going back to the prescriptive code and I am interpreting the Chinese Code (the part I had access to) to respond to many queries on typical Issues being discussed in the econference.  (China is divided into 5 seismic zones varying from Intensity 6 to 9 corresponding to    PGA 0.05g to 0.4g respectively in a 10% in 50 year event.

a)      What are the height limitations of the structural systems that may be used in each zone?
Allowable height in m. for regular buildings (roughly equiv to Importance factor of 1.0 for us)

System

Seismic Intensity 6

Seismic Intensity 7 (~ IS Zone III)

Seismic Intensity 8 (~  Zone IV)

Seismic Intensity 9
(Zone V)

Frame Only

60

50

40

NA

Frame -Shear Wall

160

140

120

100

Shear wall only (going up to ground)

170

150

130

110

(Flat) Slab-column Shear wall

80

70

55

NA

Tube with frame-corewall/Tube in tube

210/280

180/230

140/170

120/150

I have simplified it a bit, pl note.  But no such restriction in IS code


b)      What are allowable inter-story deflections?

L/550 for frame structure, L/800 for frame shear wall, frame –core wall and (flat) slab- column shear wall, L/1000 for shear wall only and tune-in-tube, L/1000 for transfer story (L=ht)- (Sangeeta Wij  had asked re. transfer floors. I hope this and the requirements for code-exceeding buildings responds partially to her query. )


The requirements are same for wind as well as standard value frequent earthquakes.

Compare this with IS Code L/500 for all structural systems for wind design and L/250 for earthquake design. (Not discussing allowable  interstory elasto-plastic displacement angle presently)


c)       What is the max allowable Aspect Ratio of a Building ?
It varies based on structural system selected and the Seismic Zone. Max allowable aspect ratio is 8 for Intensity 6/7 regions with Tube-in-tube system and max aspect ratio is 3 for a frame wall system in Intensity 8. No such restriction in IS code


d)      What is the max width to Length ratio in plan?
For intensity 6/7, length cannot be more than 6 time breadth for rectangular buildings. No such restriction in IS code


e)      What is  the max area of openings in a floor slab?
30% of floor area. No such restriction in IS code


f)       What is the max wind vibration acceleration permitted ?
Residential 0.15 m/s2, Office 0.25 m/s2. No such restriction in IS code


g)      How do you account for non-bearing masonry walls in stiffness calculations?
The Chinese code does not have empirical Time period formulae as in IS code. However it says that the stiffness of these walls may be accounted by factoring the Time period calculated through analysis by a reduction coefficient equal to 0.6~0.7 for frame buildings, 0.7~0.8 for frame-shear wall buildings, 08~1.0 for shearwall buildings.


I think this is a long enough mail for now.


Thanks and best regards,


Alpa Sheth
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Joined: 26 Jan 2003
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Location: Mumbai

PostPosted: Wed Nov 28, 2012 6:14 am    Post subject: Comparing Tall Building Design- China vs India - Part I Reply with quote

Biju,

The values given in my mail are correct.
10 millig = 0.1m/s2
You may have forgotten that 1g = 10 m/s2 hence you have got 1/10th the value.  

regards,

Alpa

biju wrote:
Dear madam,

Pls. check the acceleration values.

It can be 10 to 25 milli g, ie 0.01 to 0.025 m/s2.

regards,

Biju
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