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IS800:2007 - Response Reduction Factor for Building system
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Yogesh.Pisal
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PostPosted: Sat Feb 06, 2010 4:40 am    Post subject: IS800:2007 - Response Reduction Factor for Building system Reply with quote

Dear Friends,

Refer Tb 23, IS800:2007

What is the difference in following terms
1. Ordinary Concentrically Braced Frames (OCBF) and Special Concentrically Braced Frames (SCBF)
2. Ordinary Moment Frame(OMF) and Special Moment Frame(SMF)

As per IS1893
OMRF is for the design and detailing as per IS456 and IS800
SMRF is for the design and detailing as per IS13920, IS4326, SP6. But I have doubt whether SP6 is valid for IS800:2007

Thanks & Regards,
Yogesh Pisal
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revanwaghode
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PostPosted: Mon Feb 08, 2010 7:49 am    Post subject: IS800:2007 - Response Reduction Factor for Building system Reply with quote

Dear Sefian,
 
The difference between OCBF and SCBF is the ductile detailing of connections of brace to the beam & column.You can refer Seismic Design Manual-Volume III published by ICBO for more information.
 
Regards
Abhay


On Sat, Feb 6, 2010 at 10:10 AM, Yogesh.Pisal <forum@sefindia.org (forum@sefindia.org)> wrote:
Quote:
  Dear Friends,

Refer Tb 23, IS800:2007

What is the difference in following terms
1. Ordinary Concentrically Braced Frames (OCBF) and Special Concentrically Braced Frames (SCBF)
2. Ordinary Moment Frame(OMF) and Special Moment Frame(SMF)

As per IS1893
OMRF is for the design and detailing as per IS456 and IS800
SMRF is for the design and detailing as per IS13920, IS4326, SP6. But I have doubt whether SP6 is valid for IS800:2007

Thanks & Regards,
Yogesh Pisal







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Dr. N. Subramanian
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PostPosted: Mon Feb 08, 2010 3:25 pm    Post subject: Re: IS800:2007 - Response Reduction Factor for Building syst Reply with quote

Dear Er Pisal,

It is a very good question. Similar to RC frames, the detailing for special and ordinary Moment or Braced frames differ. IS 800 in section 12 give some detail. But AISC 341 (a free download from AISC web site-www.aisc.org) gives more details.

Many seminars on seismic design have concentrated primarily on moment frame systems. There are many cases in moderate to high seismic regions where the designer might prefer the lower cost and more efficient braced frame option.  AISC has developed a seminar that concentrates specifically on seismic braced frames. This AISC online seminar will focus on the design requirements in the 2005 AISC Seismic Provisions for Structural Steel pertaining to Special Concentrically Braced Frames (SCBF), Ordinary Concentrically Braced Frames (OCBF), and Buckling-Restrained Braced Frames (BRBF). Example problems and solutions for each type of the three braced frames will be covered.

The speaker is Rafael Sabelli, S.E., Principal at DASSE Design in San Francisco. He is a member of the AISC Task Committee on the Seismic Provisions for Structural Steel Buildings, and is the author of numerous publications on concentrically braced frames including analytical studies and design guides on buckling-restrained braced frames. He was the 2000 NEHRP Professional Fellow in Earthquake Hazard Reduction, and is the Past Chair of the Seismology Committee of the Structural Engineers Association of California.
Anyone interested may listen to this free online seminar from http://www.aisc.org/content.aspx?id=4520

Hope it is useful.

Regards,
Subramanian


Yogesh.Pisal wrote:
Dear Friends,

Refer Tb 23, IS800:2007

What is the difference in following terms
1. Ordinary Concentrically Braced Frames (OCBF) and Special Concentrically Braced Frames (SCBF)
2. Ordinary Moment Frame(OMF) and Special Moment Frame(SMF)

As per IS1893
OMRF is for the design and detailing as per IS456 and IS800
SMRF is for the design and detailing as per IS13920, IS4326, SP6. But I have doubt whether SP6 is valid for IS800:2007

Thanks & Regards,
Yogesh Pisal
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Dr. N. Subramanian
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PostPosted: Mon Feb 08, 2010 4:24 pm    Post subject: Reply with quote

Dear Er Pisal,

The following 26 numbers 1- to 1.5-hour video lectures  are also offered by AISC web site (http://www.aisc.org/content.aspx?id=4422) and are free to watch at any time (if some one wants CEUs or PDHs then they have to pay about $50 and get the certificate  when a course has been viewed and a test on the material has been successfully completed)

1. Partially Restrained and Flexible Moment Connections, June 2009
Louis F. Geschwindner, Ph.D., Vice President of Special Projects for AISC and Professor Emeritus, Penn State University

2. Got Stiffness? Designing Better Base Plates, June 2009
Barry Arnold, ARW Engineers

3. Seismic Design of Ductile Special Concentrically Braced Frames, June 2009
Constantin Christopoulos and Jefferey Packer, University of Toronto

4. Wind or Seismic Loads- Which Controls?, June 2009
Lawrence Griffis, Walter P. Moore and Associates

5. Designing Diaphragms for Ductile Systems, June 2009
W. Samuel Easterling, Virginia Tech
Colin Rogers, McGill University

6. Joist and Joist Girders as Lateral Load Resisting Frames, June 2009
James Fisher, Computerized Structural Design
7. Robust Structures, June 2009
Christopher Foley, Marquette University
Kirk Marchand, Protection Engineering Consultants

8. The Steel Specification: A Designer's Perspective, June 2009
Kurt Swensson, KSi Structural Engineers
9. Design Tips for Steel in Low or Moderate Seismic Regions, June 2009
Dominic Kelly, Simpson Gupertz and Heger
Robert Tremblay, Ecole Polytechnique
10. Connection Design Practices, June 2009
Edward Pence, Stroud Pence & Associates
Arthur Johnson, KPFF Consulting Engineers
11. Rules of Thumb for Steel Design, April 2009
Socrates Ioannides, Structural Affliliates International
12.  Seismic Design Drawing Requirements - Seismic Provisions for Structual Steel Buildings, April 2009
Lawrence Kloiber, LeJeune Steel; Larry Muir, Cives Engineering Company
13. Simple Shear Connections to HSS Columns, April 2009
Don Sherman, Ph.D., University of Wisconsin-Milwaukee
14.  Non-Destructive Examination and Special Inspection of Seismic Welding, April 2009
Mike Mayes, Mayes Testing Engineers
15.  Composite Steel Joists - Standards and Code of Standard Practice, April 2009
David Samuelson, Nucor Research and Development
Perry Green, Steel Joist Institute
16. Quality Assurance for Structural Engineering Firms, April 2009
Cliff Schwinger, Cagley Harman & Associates
17. Development and Testing of Long Span Floor Systems, April 2009
Devin Huber, Purdue University
Erika Winters-Downey, AISC
18. Green Design: Going Beyond Material Issues, April 2009
Mark Gorgolewski, Ryerson University

19. Cool Castings and Green Ideas from Europe, April 2009
Alain Nussbaumer, Swiss Federal Institute of Technology

20.  Basic Concepts in Ductile Detailing of Steel Structures, April 2008
Michael D. Engelhardt, P.E., Ph.D., University of Texas at Austin

21.Seismic Design and Behavior of Composite RCS Frames, March 2008
Gregory Deirelein, P.E., Ph.D., Stanford University
22.  A New Approach to Design for Stability, February 2008
R. Shankar Nair, S.E., P.E., Ph.D., Teng & Associates
23.  Basic Introduction to Nonlinear Analysis, January 2008
Ronald Ziemian, P.E., Ph.D., Bucknell University

24. High Strength Bolting - The Essentials, December 2007
Geoff Kulak P.E., Ph.D., University of Alberta
25.  Fatigue and Fracture Control in Steel Structures, November 2007
Stanley Rolfe, P.E., Ph.D., University of Kansas

26. Shakedown Behavior of Steel Structures, October 2007
Theodore Galambos, Ph.D., P.E.

Hope some Sefians will attend and get the benefit.

Regards,
Subramanian
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Yogesh.Pisal
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PostPosted: Tue Feb 09, 2010 2:02 am    Post subject: Reply with quote

Respected Dr N Subramanian Sir,

Thanks for the reply.

Regards,
Yogesh Pisal
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ahujavipul
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PostPosted: Tue Feb 09, 2010 9:39 am    Post subject: Re: IS800:2007 - Response Reduction Factor for Building syst Reply with quote

I attended a lecture where slides on Special Concentric Braced frames (based on AISC) were shown. The gusset sizes appeared horrendous (almost appeared 20% of length of brace). This was cited as the reason for virtual discontinued usage of these type of braced frames & invention of the Buckling restrained braced frames.

In an earlier post I had given reasons why single story factory shed type buildings should be exempted from ductile detailing requirements. This was a major factor in making the statement. I can understand that if there is snow then that is an exception, but for most cases its ridiculous to provide ductile detailing for sheds when wind loads are virtually 10 times EQ loads.

Regards

Vipul Ahuja
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Dr. N. Subramanian
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PostPosted: Tue Feb 09, 2010 3:25 pm    Post subject: Re: IS800:2007 - Response Reduction Factor for Building syst Reply with quote

Dear Er Vipul Ahuja,

I also agree with you that if the wind load governs, especially in single storey industrial buildings, it is not necessary to provide EQ ductile detailing.

Yes. the gusset plate size becomes very large in Spl. conc. braced frames. as you have said rightly, in  Buckling restrained braced frames the gusset plate sizes can be reduced considerably. Do you know that our own Er B N Sridhara of Bangalore is behind this invention of Buckling restrained braced frames?

You may be interested to read the following paper:
Thornton, W.A., Muir, L.S. Design of vertical bracing connections for high-seismic drift, Modern Steel Construction, Vol. 49, No.3, Mar 2009, pp.61-65 (http://www.modernsteel.com/Uploads/Issues/March_2009/032009_thorton_nascc-web.pdf)

Regards,
Subramanian

ahujavipul wrote:
I attended a lecture where slides on Special Concentric Braced frames (based on AISC) were shown. The gusset sizes appeared horrendous (almost appeared 20% of length of brace). This was cited as the reason for virtual discontinued usage of these type of braced frames & invention of the Buckling restrained braced frames.

In an earlier post I had given reasons why single story factory shed type buildings should be exempted from ductile detailing requirements. This was a major factor in making the statement. I can understand that if there is snow then that is an exception, but for most cases its ridiculous to provide ductile detailing for sheds when wind loads are virtually 10 times EQ loads.

Regards

Vipul Ahuja
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ahujavipul
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PostPosted: Tue Feb 09, 2010 5:44 pm    Post subject: IS800:2007 - Response Reduction Factor for Building syst Reply with quote

Dear Dr. NS,

I feel proud that an Indian (Er B N Sridhara) was behind this pioneering work. However its a pity that structural designers in India have not pushed for adopting BRBF's--perhaps due to lack of design experience in SCBF's.

I feel the concept of BRBF's is so simple yet even in the US its become an expensive specialized item. I'm sure if its introduced in India it won't be long before someone comes up with a "jugad" at a fraction of the cost.

Also we should push for a code change (in IS 800) to make exceptions in doing ductile detailing in single story shed type steel structures where wind loads overwhelmingly dominate EQ forces.

Regards

Vipul Ahuja
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Dr. N. Subramanian
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PostPosted: Thu Feb 11, 2010 1:24 am    Post subject: Re: IS800:2007 - Response Reduction Factor for Building syst Reply with quote

Dear Er Vipul Ahuja,

The BRBF systems used here in USA are all proprietary: www.starseismic.net, www.CoreBrace.com

CoreBrace currently has two patents and three other patents pending, while Star Seismic has three patents to date. Both are based on the invention by Er Sridhara. Japan's Nippon’s BRB is called Unbonded Brace.

The first BRBF system was installed in the United States at UC-Davis in January 2000. The cost of BRBF systems have dropped significantly the past three years.

More details of these systems may be found in: http://www.coffman.com/documents/news/industry_articles/brbfpaperfinal.pdf

Regards,
Subramanian
ahujavipul wrote:
Dear Dr. NS,

I feel proud that an Indian (Er B N Sridhara) was behind this pioneering work. However its a pity that structural designers in India have not pushed for adopting BRBF's--perhaps due to lack of design experience in SCBF's.

I feel the concept of BRBF's is so simple yet even in the US its become an expensive specialized item. I'm sure if its introduced in India it won't be long before someone comes up with a "jugad" at a fraction of the cost.

Also we should push for a code change (in IS 800) to make exceptions in doing ductile detailing in single story shed type steel structures where wind loads overwhelmingly dominate EQ forces.

Regards

Vipul Ahuja
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ahujavipul
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PostPosted: Fri Feb 12, 2010 1:49 pm    Post subject: Re: IS800:2007 - Response Reduction Factor for Building syst Reply with quote

Dear Dr. NS,

Thanks for the paper. The picture of the SCBF in this is probably the same one quoted earlier. And one can see the ridiculous sizes. I was wondering if you know the initial cost impact of BRBF's on a typical steel building when compared with an SCBF building.

Thanks & regards,

Vipul Ahuja



drnsmani wrote:
Dear Er Vipul Ahuja,

The BRBF systems used here in USA are all proprietary: www.starseismic.net, www.CoreBrace.com

CoreBrace currently has two patents and three other patents pending, while Star Seismic has three patents to date. Both are based on the invention by Er Sridhara. Japan's Nippon’s BRB is called Unbonded Brace.

The first BRBF system was installed in the United States at UC-Davis in January 2000. The cost of BRBF systems have dropped significantly the past three years.

More details of these systems may be found in: http://www.coffman.com/documents/news/industry_articles/brbfpaperfinal.pdf

Regards,
Subramanian
ahujavipul wrote:
Dear Dr. NS,

I feel proud that an Indian (Er B N Sridhara) was behind this pioneering work. However its a pity that structural designers in India have not pushed for adopting BRBF's--perhaps due to lack of design experience in SCBF's.

I feel the concept of BRBF's is so simple yet even in the US its become an expensive specialized item. I'm sure if its introduced in India it won't be long before someone comes up with a "jugad" at a fraction of the cost.

Also we should push for a code change (in IS 800) to make exceptions in doing ductile detailing in single story shed type steel structures where wind loads overwhelmingly dominate EQ forces.

Regards

Vipul Ahuja
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