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CA, USA "San Andreas fault could be twice as damaging as previously thought

 
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VPandya
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PostPosted: Thu Nov 17, 2016 4:59 pm    Post subject: CA, USA "San Andreas fault could be twice as damaging as previously thought Reply with quote

Dear  Sefi Engrs. ,
Read this new projection for CA , USA ( Highest  Seismic Zone in USA).  San Andreas fault could be twice as damaging  as previously thought.

From  Latest : ACI’S  ConcreteSmart Brief: 16th Nov. 2016.

Report:  Major quake on San Andreas fault could be twice as damaging as previously thought.  
Analysts  release grim forecast of potential destruction along San Andreas Fault (California,USA):

Web-Link:  
http://www.sgvtribune.com/general-news/20161115/report-major-quake-on-san-andreas-fault-could-be-twice-as-damaging-as-previously-thought


Previous History Of  City Of San Francisco damage due to Earthquakes, CA , USA : When in USA I live in this great City Of San Francisco and when  in India  I live in  Ahmedabad.

The 1906 San Francisco earthquake struck the coast of Northern California at 5:12 a.m
. onApril 18 with an estimated moment magnitude of 7.8 and a maximum Mercalli intensity of XI (Extreme).Severe shaking was felt from Eureka on the North Coast to the SalinasValley, an agricultural region to the south of the San Francisco Bay Area. Devastating fires soon broke out in the city and lasted for several days. As a result, about3,000 people died and over 80% of the city of  San Francisco was destroyed. The events are remembered as one of the worst and deadliest natural disasters in the history of the United States. The death toll remains the greatest loss of life from a natural disaster in California's history and high in the lists of American urban disasters.

Question: Planned New  SKYLINE ( High Rise Buildings) for  AHMEDABAD:
In a recent news paper  story,  I read that Builders are planning a new SKY LINE for  AHMEDABAD. There will be many new High Rise buildings in Ahmedabad.  During BHUJ EARTHQUAKE  of  2001 Ahmedabad  suffered great losses. What has changed in quality of Design and Construction of HIGH-RISE Buildings in Ahmedabad since 2001 ?   I know we are in Seismic ZONE III, but  I am still concerned.


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Vasudeo Pandya P.E.
Structural Engineer
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N. Prabhakar
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PostPosted: Fri Nov 18, 2016 2:01 pm    Post subject: Reply with quote

Dear Er. Pandyaji,

I agree with your concern about living in high-rise buildings in Ahmedabad which is in Seismic Zone III.  Following the Bhuj Earthquake in 2001, IS code  IS 1893( Part 1 ) :2002  has been modified slightly from the previous code of 1984.  As far as the structural analysis of earthquake resistant structures is concerned, it is not a problem as many structural design engineers these days use computer software like Staad pro and Etabs which are in order provided the structural model, design parameters and assumptions considered are right.

The main problem is in the preparation of detail drawings to meet the requirements of ductile detailing as per IS 13920 : 1993 (Reaffirmed 2003). As per this code, ductile detailing is required for Seismic Zone III with Importance Factor greater than 1.0, industrial structures and structures more than 5 storey high.  Ductile detailing gives importance to curtailment and lapping of beam and column bars at particular locations, anchorage of beam bars, and spacing of links and stirrups in beams and columns near joints, which can be shown only by drawing elevations of column-beam frames with bar bending schedule on the drawings. But as I know, not many structural consultants in India do follow these rules strictly in the preparation of drawings, and still prepare it in a simple schedule format.  The absence of ductile detailing would result in initial failure of joints and eventual structural collapse in some cases. Mumbai is also in Seismic Zone III like Ahmedabad.  I just wonder how many high-rise buildings, more than 5 storey high, which are there too many in Mumbai, have drawings prepared for ductile detailing.  It is a serious concern for Mumbai people also.

With best wishes,

N. Prabhakar
Chartered Structural Engineer
Vasai (E), Pin 401 208
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VPandya
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PostPosted: Fri Nov 18, 2016 4:31 pm    Post subject: Yes seismic ductile detailing required for Zone III. Reply with quote

Dear  Er.  Prabhakarji,

Thanks for a very detail post on requirements of SEISMIC  DUCTILE  DETAILING.  In India we Structural Engineers have  code  IS 13920 : 1993 ( Reaffirmed 2003)  for  Ductile detailing . In US we also have Seismic Detailing Manuals meeting ACI-318-11  Chapter 21  Code . They exactly gives actual Seismic ductile detailing  drawings ( Details) so we do not have to  guess  what the intent of  ACI 318-11 , Chapter -21 code is. It helps a lot to copy these Joint  (Meeting our project requirements) details on final GFC  Drawings. I am sure there is a need of such Seismic  Ductile  Detailing Manuals for IS 13920 code,  if we do not already  have them. Will improve quality of final ( GFC) drawings

Regards.

Vasudeo  Pandya P.E.
Structural Engineer


Last edited by VPandya on Sat Nov 19, 2016 5:39 am; edited 1 time in total
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Dr. N. Subramanian
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PostPosted: Sat Nov 19, 2016 3:44 am    Post subject: Re: Yes seismic ductile detailing required for Zone III. Reply with quote

Dear Er Prabhakar and Er Pandya,

I agree with both of you that many buildings in India are not provided with ductile detailing, which is a cause to worry, especially in high seismic zones. Though the codes in the area of EQ design and detailing are being revised at regular intervals, (the codes in other areas take more than 20 to 25 years to update in India), they are not implemented.  Even in non-EQ zones, proper detailing is not done and it is the main reason for failures like that happened in the Kolkata Flyover (steel Structure) and the 11 storey building in Chennai(Concrete Structure).


http://www.thehindu.com/multimedia/dynamic/01974/TH29_BUILDING_1974465g.jpg">

Moreover, the builders are concentrating on external appearance, which will fetch them more profit, than the skeletal things which are important for the health and life of the structures. There is an important need to educate the engineers and all those engaged in the construction industry.

Please note that the new version of IS 1893(Part 1) is under print by BIS and the 2016 version of IS 13920 has already been issued by BIS.

Warm regards
NS
VPandya wrote:
Dear  Er.  Prabhakarji,

Thanks for a very detail post on requirements of SEISMIC  DUCTILE  DETAILING.  In India we Structural Engineers have  code  IS 13920 : 1993 ( Reaffirmed 2003)  for  Ductile detailing . In US we also have Seismic Detailing Manuals meeting ACI-318-11  Chapter 21  Code . They exactly gives actual Seismic ductile detailing  drawings ( Details) so we do not have to  guess  what the intent of  ACI 318-11 , Chapter -21 code is. It helps a lot to copy these Joint  (Meeting our project requirements) details on final GFC  Drawings. I am sure there is a need of such Seismic  Ductile  Detailing Manuals for IS 13920 code,  if we dot already  have them. Will improve quality of final ( GFC) drawings

Regards.

Vasudeo  Pandya P.E.
Structural Engineer
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B.V.Harsoda
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PostPosted: Sat Nov 19, 2016 1:42 pm    Post subject: Reply with quote

Dear Er. N. Prabhakar Sir,

You Have quote reference of old IS 13920 :1993. I know that you are aware of Revised IS 13920: 2016 as you have already discussed about revised code at below Link:-

http://www.sefindia.org/forum/viewtopic.php?t=18048

Regards,
Er. B. V. Harsoda




N. Prabhakar wrote:
Dear Er. Pandyaji,

I agree with your concern about living in high-rise buildings in Ahmedabad which is in Seismic Zone III.  Following the Bhuj Earthquake in 2001, IS code  IS 1893( Part 1 ) :2002  has been modified slightly from the previous code of 1984.  As far as the structural analysis of earthquake resistant structures is concerned, it is not a problem as many structural design engineers these days use computer software like Staad pro and Etabs which are in order provided the structural model, design parameters and assumptions considered are right.

The main problem is in the preparation of detail drawings to meet the requirements of ductile detailing as per IS 13920 : 1993 (Reaffirmed 2003). As per this code, ductile detailing is required for Seismic Zone III with Importance Factor greater than 1.0, industrial structures and structures more than 5 storey high.  Ductile detailing gives importance to curtailment and lapping of beam and column bars at particular locations, anchorage of beam bars, and spacing of links and stirrups in beams and columns near joints, which can be shown only by drawing elevations of column-beam frames with bar bending schedule on the drawings. But as I know, not many structural consultants in India do follow these rules strictly in the preparation of drawings, and still prepare it in a simple schedule format.  The absence of ductile detailing would result in initial failure of joints and eventual structural collapse in some cases. Mumbai is also in Seismic Zone III like Ahmedabad.  I just wonder how many high-rise buildings, more than 5 storey high, which are there too many in Mumbai, have drawings prepared for ductile detailing.  It is a serious concern for Mumbai people also.

With best wishes,

N. Prabhakar
Chartered Structural Engineer
Vasai (E), Pin 401 208
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N. Prabhakar
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PostPosted: Sun Nov 20, 2016 5:59 am    Post subject: Reply with quote

Dear Er. Harsodaji,

Thank you for correcting me on the latest version of IS 13920 in my previous posting. I agree that the 2016 version of the code has been redrafted with a few changes in certain clauses of the earlier 1993 version. But, nonetheless, it hasn't been made any easier for the preparation of drawings for ductile detailing.  The points I had raised in my previous posting on this subject matter remain still valid.   I repeat that complex ductile detailing can be done only by showing reinforcement details in elevations of column-beam frames with bar bending schedule on the drawings, and not by just showing it in a simple schedule format, as is the current practice with most structural consultants.

With best wishes,

N. Prabhakar
Chartered Structural Engineer
Vasai (E), Pin 401 208
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struct4me
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PostPosted: Mon Nov 21, 2016 5:29 am    Post subject: IS 1893 Reply with quote

Sir

In this regard, I want to know, when the final revised copies of other part of the 1893 (part 2 to 5 except part 4 ) will come out finally. Is it not strange that after 2002, when the main EQ code was modified, we are waiting for the official release of other parts (not the drafted) for more than 14 years. I feel sorry of the Committee who is looking after this.

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PostPosted: Wed Nov 23, 2016 9:31 am    Post subject: ACI Seismic Ductile Detailing Manual based on ACI code. Reply with quote

Dear  Er.  Prabhakarji and Er. B.V.Harsodaji,

I am attaching  few pages from  " Seismic  Detailing Of Concrete Buildings,  by David A. Fanella ". This manual is based on ACI code and published by PCA ( Portland Cement Association).  For proper/correct  use of latest   IS 13920 2016 ( IS 13920 : Ductile detailing of reinforced concrete structures ) we need such publications.  This will be a great help in producing correct GFC drawings with Seismic Ductile Detailing. Not only this manual gives sketches ( Drawings ) but Design/engineering calculations to produce such details.

Regards.

Vasudeo  Pandya  P.E.  
Structural Engineer



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PostPosted: Wed Nov 23, 2016 1:28 pm    Post subject: Reply with quote

Dear Er. Pandyaji,

Thank you for posting a few pages of a published manual for ductile detailing based on ACI code, and as practiced in America.  No doubt, such manuals would help in producing right calculations and drawings to meet the requirements of ductile detailing.

In India, IIT Kanpur has published some interesting technical papers on the subject, and these are:

1.  http://www.iitk.ac.in/nicee/IITK-GSDMA/EQ22.pdf
     Explanatory Examples for Ductile Detailing
     of RC Buildings

2. http://www.iitk.ac.in/nicee/IITK-GSDMA/EQ11.pdf
    Commentary on Ductile Detailing of RC Structures Subjected to     
    Seismic Forces

Besides, Indian code IS 13920 also shows necessary figures for ductile detailing of beams, columns, etc.

The problem is not in the lack of technical publications in India on the subject, but it is in the implementation of the details on the drawings by structural consultants.  It requires a lot of effort by them, as compared to the present practice of just putting it in a simple schedule format, for which he/she is not paid adequately as has been discussed several times in this forum. The present trend is that structural consultants are looking for computer software that can produces drawings automatically by reading the outputs of structural analysis  and design prepared by another software like Staad pro and Etabs.  I do not know whether such a computer software can really produce detail drawings showing curtailment and lapping of beam and column bars at particular locations, anchorage of beam bars, and spacing of links and stirrups in beams and columns near joints, all in elevations of column-beam frames with bar bending schedule,  to meet the requirements of ductile detailing as per IS 13920.

With best wishes,

N. Prabhakar
Chartered Structural Engineer
Vasai (E), Pin 401 208
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VPandya
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PostPosted: Fri Jun 16, 2017 12:21 am    Post subject: These Tall High Rise buildings are safe in Earthquakes, examples. Reply with quote

Dear Sefi Friends,

These Tall High Rise buildings are safe in  Earthquakes, examples.  
From latest ACI Concrete ,  
SmartBrief. 15 June 2017 :    
These 7 quake-resistant buildings  
are designed to withstand the next  
big shockwave.

Web—Link  :

https://www.digitaltrends.com/cool-tech/earthquake-resistant-buildings/

Regards.

Vasudeo Pandya  P.E.
Structural Engineer


Last edited by VPandya on Fri Jun 16, 2017 2:10 am; edited 3 times in total
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