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Seismic Design
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thirumalaichettiar
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PostPosted: Fri Apr 01, 2011 11:33 am    Post subject: Seismic Design Reply with quote

I have read the following from a steel book:

In US practice, however, certain steel types are excluded from seismic-resisting
structures by the AISC standard, and minimum Charpy notch toughness values
are also specified where the steel thickness exceeds 30 mm.

Is there any restrictions in Indian Codes? If so please specify.

Are our Steel Industry manufacture a steel specially for Seismic ?

If anybody has information can post it please.

T.RangaRajan.


Note:

I request the Admin to make this topic as Sticky so that I can post many technical notes now and then  for the analysis and design against Seismic.


Last edited by thirumalaichettiar on Wed Apr 06, 2011 11:48 am; edited 1 time in total
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thirumalaichettiar
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PostPosted: Fri Apr 01, 2011 12:07 pm    Post subject: Reply with quote

I request all sefians kindly post only under this Sticky topic your technical notes as you are well aware that Seismic design is a vast subject and we need to learn a lot both in analysis and design, construction and also use of many software.

Hope sefians will not put this subject on a scattered places.

Special thanks to Mr.Sanjeev,Admin for placing this topic under STICKY immediately.


T.RangaRajan.


Last edited by thirumalaichettiar on Fri Apr 01, 2011 4:15 pm; edited 1 time in total
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thirumalaichettiar
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PostPosted: Fri Apr 01, 2011 12:22 pm    Post subject: Reply with quote

Need Seniors and experienced engineers share their ideas for the following doubts?

FIRST LIST OF QUESTIONS:

1.Which material is good for Seismic?STEEL,CONCRETE,MASONRYAND TIMBER etc.

2.Can we use other than steel like fiberglass bars(GRP), aluminium bars etc as steel reinforcement?

3.When P-Delta effect will have to be considered? Its effect on concrete and steel structures?

4.Can we make use of Concrete of grade greater than M50 as it becomes more brittle on higher grade?

5. Can we use Fy=550 steel bars if the elongation is less than 14.5%?

6. Why the codes specify the limits on b/Dor the dimensional restrictions for EQ design?

7.When need to consider the Vertical force of EQ ?

8. Is Equivalent Static method consider the Vertical force of Earthquake?

9. Why moment redistribution is not considered in EQ analysis?

10.If a structure has long span or if the cantilever is more than 5m is worth to neglect the vertical force of EQ?

More to come.
  
T.RangaRajan


Last edited by thirumalaichettiar on Thu Apr 07, 2011 12:12 pm; edited 4 times in total
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thirumalaichettiar
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PostPosted: Fri Apr 01, 2011 12:24 pm    Post subject: Reply with quote

Sefians are requested to go through the EXPERTS FORUM in the Sefi where I have posted many notes on seismic which are very good to learn.

T.RangaRajan.
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thirumalaichettiar
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PostPosted: Fri Apr 01, 2011 1:19 pm    Post subject: Reply with quote

Please visit the web site for pictures:

http://www.amerrescue.org/

What to do During an Earthquake

Remember that stuff about hiding under a table or standing in a doorway? Well, forget it! This is a real eye opener. It could save your life someday.

EXTRACT FROM DOUG COPP'S ARTICLE ON 'THE TRIANGLE OF LIFE'

My name is Doug Copp. I am the Rescue Chief and Disaster Manager of the American Rescue Team International (ARTI ), the world's most experienced rescue team. The information in this article will save lives in an earthquake.

I have crawled inside 875 collapsed buildings, worked with rescue teams from 60 countries, founded rescue teams in several countries, and I am a member of many rescue teams from many countries. I was the United Nations expert in Disaster Mitigation for two years, and have worked at every major disaster in the world since 1985, except for simultaneous disasters.

The first building I ever crawled inside of was a school in Mexico City during the 1985 earthquake. Every child was under its desk. Every child was crushed to the thickness of their bones. They could have survived by lying down next to their desks in the aisles. It was obscene -- unnecessary.

Simply stated, when buildings collapse, the weight of the ceilings falling upon the objects or furniture inside crushes these objects, leaving a space or void next to them - NOT under them. This space is what I call the 'triangle of life'. The larger the object, the stronger, the less it will compact. The less the object compacts, the larger the void, the greater the probability that the person who is using this void for safety will not be injured. The next time you watch collapsed buildings, on television, count the 'triangles' you see formed. They are everywhere. It is the most common shape, you will see, in a collapsed building.

TIPS FOR EARTHQUAKE SAFETY

1) Most everyone who simply 'ducks and covers' when building collapse are crushed to death. People who get under objects, like desks or cars, are crushed.

2) Cats, dogs and babies often naturally curl up in the fetal position. You should too in an earthquake. It is a natural safety/survival instinct. You can survive in a smaller void. Get next to an object, next to a sofa, next to a bed, next to a large bulky object that will compress slightly but leave a void next to it.

3) Wooden buildings are the safest type of construction to be in during an earthquake. Wood is flexible and moves with the force of the earthquake. If the wooden building does collapse, large survival voids are created. Also, the wooden building has less concentrated, crushing weight. Brick buildings will break into individual bricks. Bricks will cause many injuries but less squashed bodies than concrete slabs.

4) If you are in bed during the night and an earthquake occurs, simply roll off the bed. A safe void will exist around the bed. Hotels can achieve a much greater survival rate in earthquakes, simply by posting a sign on the back of the door of every room telling occupants to lie down on the floor, next to the bottom of the bed during an earthquake.

5) If an earthquake happens and you cannot easily escape by getting out the door or window, then lie down and curl up in the fetal position next to a sofa, or large chair.

6) Most everyone who gets under a doorway when buildings collapse is killed. How? If you stand under a doorway and the doorjamb falls forward or backward you will be crushed by the ceiling above. If the door jam falls sideways you will be cut in half by the doorway. In either case, you will be killed!

7) Never go to the stairs. The stairs have a different 'moment of frequency' (they swing separately from the main part of the building). The stairs and remainder of the building continuously bump into each other until structural failure of the stairs takes place. The people who get on stairs before they fail are chopped up by the stair treads - horribly mutilated. Even if the building doesn't collapse, stay away from the stairs. The stairs are a likely part of the building to be damaged. Even if the stairs are not collapsed by the earthquake, they may collapse later when overloaded by fleeing people. They should always be checked for safety, even when the rest of the building is not damaged.

Cool Get near the outer walls of buildings or outside of them if possible - It is much better to be near the outside of the building rather than the interior. The farther inside you are from the outside perimeter of the building the greater the probability that your escape route will be blocked.

9) People inside of their vehicles are crushed when the road above falls in an earthquake and crushes their vehicles; which is exactly what happened with the slabs between the decks of the Nimitz Freeway. The victims of the San Francisco earthquake all stayed inside of their vehicles. They were all killed. They could have easily survived by getting out and sitting or lying next to their vehicles. Everyone killed would have survived if they had been able to get out of their cars and sit or lie next to them. All the crushed cars had voids 3 feet high next to them, except for the cars that had columns fall directly across them.

10) I discovered, while crawling inside of collapsed newspaper offices and other offices with a lot of paper, that paper does not compact. Large voids are found surrounding stacks of paper.

Spread the word and save someone's life...

The entire world is experiencing natural calamities so be prepared!

'We are but angels with one wing, it takes two to fly'

In 1996 we made a film, which proved my survival methodology to be correct. The Turkish Federal Government, City of Istanbul , University of Istanbul Case Productions and ARTI cooperated to film this practical, scientific test. We collapsed a school and a home with 20 mannequins inside. Ten mannequins did 'duck and cover,' and ten mannequins I used in my 'triangle of life' survival method. After the simulated earthquake collapse we crawled through the rubble and entered the building to film and document the results. The film, in which I practiced my survival techniques under directly observable, scientific conditions, relevant to building collapse, showed there would have been zero percent survival for those doing duck and cover.

There would likely have been 100 percent survivability for people using my method of the 'triangle of life.' This film has been seen by millions of viewers on television in Turkey and the rest of Europe, and it was seen in the USA, Canada and Latin America on the TV program Real TV.
"Triangle of Life":

Without listening or reading, simply by looking at the following self-explanatory photos, you can learn more than in a thousand words about how to protect yourself during a major earthquake...


If you are inside a vehicle, come out and sit or lie down next to it. If something falls on the vehicle, it will leave an empty space along the sides. See below:

Source:國際救援小組(ARTI),網址:http://www.amerrescue.org/
      ( American Rescue Team International(ARTI)is said to be the World's most experienced rescue team and disaster
       management-mitigation organization.)

T.RangaRajan.
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thirumalaichettiar
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PostPosted: Fri Apr 01, 2011 4:14 pm    Post subject: Reply with quote

Determining structural periods of buildings:

The period of an undamped mass supported on a spring is equal to 2 .pie sq.rt of M/K

A useful approximation for buildings with a regular distribution of mass and stiffness is
T is approximately equal to 2.sq.rt of delta(seconds)

where delta  is the lateral deflection in metres of the top of the building when  subjected to its gravity loads acting horizontally;
period depends on the square root of mass divided by stiffnesses, so large changes in mass and stiffness are needed for a significant change in period. By contrast mounting the building on flexible bearings can dramatically increase the period.

As a rough initial guide, the fundamental period of
a building is N=10.

T.RangaRajan.
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thirumalaichettiar
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PostPosted: Fri Apr 01, 2011 4:31 pm    Post subject: Reply with quote

Some of the following may be silly but need to understand to know more.

SECOND LIST OF QUESTIONS:

1.    Why there is a different load combination for concrete and steel member in the code?
2.    When to provide shear walls? What are the types ?
3.    How to make R.C.C member more ductile?
4.    What type of support condition will be having good seismic effect?
5.    What is liquefaction and what are the means to reduce it?
6.    What types of failures that control design of concrete and steel structure?
7. Why the member stiffness have to be reduced and what are the values to be used for
    A.      Slab.
    B.     Wall.
    C.      Beam.
    D.     column.
8. What is the CAPTIVE COLUMN? How this can be  considered with respect to EQ?
9. How to avoid POUNDING effect of structures?
10. What is the effect of infill masonry in RC frames?
11. When the Shear wall is proposed and what is its limit with respect to EQ?

Hope senior and experience engineers can bestow their reply forthe benefit of all.

T.RangaRajan.


Last edited by thirumalaichettiar on Thu Apr 07, 2011 12:13 pm; edited 1 time in total
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Dr. N. Subramanian
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PostPosted: Fri Apr 01, 2011 6:45 pm    Post subject: Reply with quote

Dear Er Rangarajan Sir,

Very good advice. Makes sense.

Regards,
Subramanian
thirumalaichettiar wrote:
Please visit the web site for pictures:

http://www.amerrescue.org/

What to do During an Earthquake

Remember that stuff about hiding under a table or standing in a doorway? Well, forget it! This is a real eye opener. It could save your life someday.

EXTRACT FROM DOUG COPP'S ARTICLE ON 'THE TRIANGLE OF LIFE'

My name is Doug Copp. I am the Rescue Chief and Disaster Manager of the American Rescue Team International (ARTI ), the world's most experienced rescue team. The information in this article will save lives in an earthquake.

I have crawled inside 875 collapsed buildings, worked with rescue teams from 60 countries, founded rescue teams in several countries, and I am a member of many rescue teams from many countries. I was the United Nations expert in Disaster Mitigation for two years, and have worked at every major disaster in the world since 1985, except for simultaneous disasters.

The first building I ever crawled inside of was a school in Mexico City during the 1985 earthquake. Every child was under its desk. Every child was crushed to the thickness of their bones. They could have survived by lying down next to their desks in the aisles. It was obscene -- unnecessary.

Simply stated, when buildings collapse, the weight of the ceilings falling upon the objects or furniture inside crushes these objects, leaving a space or void next to them - NOT under them. This space is what I call the 'triangle of life'. The larger the object, the stronger, the less it will compact. The less the object compacts, the larger the void, the greater the probability that the person who is using this void for safety will not be injured. The next time you watch collapsed buildings, on television, count the 'triangles' you see formed. They are everywhere. It is the most common shape, you will see, in a collapsed building.

TIPS FOR EARTHQUAKE SAFETY

1) Most everyone who simply 'ducks and covers' when building collapse are crushed to death. People who get under objects, like desks or cars, are crushed.

2) Cats, dogs and babies often naturally curl up in the fetal position. You should too in an earthquake. It is a natural safety/survival instinct. You can survive in a smaller void. Get next to an object, next to a sofa, next to a bed, next to a large bulky object that will compress slightly but leave a void next to it.

3) Wooden buildings are the safest type of construction to be in during an earthquake. Wood is flexible and moves with the force of the earthquake. If the wooden building does collapse, large survival voids are created. Also, the wooden building has less concentrated, crushing weight. Brick buildings will break into individual bricks. Bricks will cause many injuries but less squashed bodies than concrete slabs.

4) If you are in bed during the night and an earthquake occurs, simply roll off the bed. A safe void will exist around the bed. Hotels can achieve a much greater survival rate in earthquakes, simply by posting a sign on the back of the door of every room telling occupants to lie down on the floor, next to the bottom of the bed during an earthquake.

5) If an earthquake happens and you cannot easily escape by getting out the door or window, then lie down and curl up in the fetal position next to a sofa, or large chair.

6) Most everyone who gets under a doorway when buildings collapse is killed. How? If you stand under a doorway and the doorjamb falls forward or backward you will be crushed by the ceiling above. If the door jam falls sideways you will be cut in half by the doorway. In either case, you will be killed!

7) Never go to the stairs. The stairs have a different 'moment of frequency' (they swing separately from the main part of the building). The stairs and remainder of the building continuously bump into each other until structural failure of the stairs takes place. The people who get on stairs before they fail are chopped up by the stair treads - horribly mutilated. Even if the building doesn't collapse, stay away from the stairs. The stairs are a likely part of the building to be damaged. Even if the stairs are not collapsed by the earthquake, they may collapse later when overloaded by fleeing people. They should always be checked for safety, even when the rest of the building is not damaged.

Cool Get near the outer walls of buildings or outside of them if possible - It is much better to be near the outside of the building rather than the interior. The farther inside you are from the outside perimeter of the building the greater the probability that your escape route will be blocked.

9) People inside of their vehicles are crushed when the road above falls in an earthquake and crushes their vehicles; which is exactly what happened with the slabs between the decks of the Nimitz Freeway. The victims of the San Francisco earthquake all stayed inside of their vehicles. They were all killed. They could have easily survived by getting out and sitting or lying next to their vehicles. Everyone killed would have survived if they had been able to get out of their cars and sit or lie next to them. All the crushed cars had voids 3 feet high next to them, except for the cars that had columns fall directly across them.

10) I discovered, while crawling inside of collapsed newspaper offices and other offices with a lot of paper, that paper does not compact. Large voids are found surrounding stacks of paper.

Spread the word and save someone's life...

The entire world is experiencing natural calamities so be prepared!

'We are but angels with one wing, it takes two to fly'

In 1996 we made a film, which proved my survival methodology to be correct. The Turkish Federal Government, City of Istanbul , University of Istanbul Case Productions and ARTI cooperated to film this practical, scientific test. We collapsed a school and a home with 20 mannequins inside. Ten mannequins did 'duck and cover,' and ten mannequins I used in my 'triangle of life' survival method. After the simulated earthquake collapse we crawled through the rubble and entered the building to film and document the results. The film, in which I practiced my survival techniques under directly observable, scientific conditions, relevant to building collapse, showed there would have been zero percent survival for those doing duck and cover.

There would likely have been 100 percent survivability for people using my method of the 'triangle of life.' This film has been seen by millions of viewers on television in Turkey and the rest of Europe, and it was seen in the USA, Canada and Latin America on the TV program Real TV.
"Triangle of Life":

Without listening or reading, simply by looking at the following self-explanatory photos, you can learn more than in a thousand words about how to protect yourself during a major earthquake...


If you are inside a vehicle, come out and sit or lie down next to it. If something falls on the vehicle, it will leave an empty space along the sides. See below:

Source:國際救援小組(ARTI),網址:http://www.amerrescue.org/
      ( American Rescue Team International(ARTI)is said to be the World's most experienced rescue team and disaster
       management-mitigation organization.)

T.RangaRajan.
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Dr. N. Subramanian
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PostPosted: Fri Apr 01, 2011 7:02 pm    Post subject: Reply with quote

Dear Er Ragarajan Sir,

Very good questions. I need time to answer. I will answer a few now.
1.Which material is good for Seismic?STEEL,CONCRETE,MASONRYAND TIMBER etc.

I would prefer Steel because it has equal strength in tension and compression- Moreover it is mostly prefabricated at factory and hence has good quality control. Only experienced and qualified persons normally design and work on steel structures. It is also demountable and totally recyclable. Only problem is that it is expensive than other materials. The recent behaviour of steel structures in Japan (the joints were perfected after the 1994 Northridge(USA) and Kobe (Japan) earthquakes) is testimony for their use.

Concrete structures ares OK if they are designed, detailed and executed properly at site. Masonry is not at all suitable unless it is reinforced.
The advantage of wood are they are light weight and hence EQ forces may be less. They are good for sustainability angle. Even if the structure fails, it is easy to cut and save persons-Concrete is the worst in this regard.
2.Can we use other than steel like fiberglass bars(GRP), aluminium bars etc as steel reinforcement?

They should not be used in EQ Zones as their ductility is small.

3.When P-Delta effect will have to be considered? Its effect on concrete and steel structures?
P-Delta effects have to be considered in EQ zones, especially for tall buildings. The effect will be same immaterial of the type of material used. Their effect will be less if one provides concrete shear walls are steel plate shear walls or damping systems.

Regards
Subramanian
P.s. Will I get marks for answering the questions?
thirumalaichettiar wrote:
Need Seniors and experienced engineers share their ideas for the following doubts?

1.Which material is good for Seismic?STEEL,CONCRETE,MASONRYAND TIMBER etc.

2.Can we use other than steel like fiberglass bars(GRP), aluminium bars etc as steel reinforcement?

3.When P-Delta effect will have to be considered? Its effect on concrete and steel structures?

4.Can we make use of Concrete of grade greater than M50 as it becomes more brittle on higher grade?

5. Can we use Fy=550 steel bars if the elongation is less than 14.5%?

6. Why the codes specify the limits on b/Dor the dimensional restrictions for EQ design?

7.When need to consider the Vertical force of EQ ?

8. Is Equivalent Static method consider the Vertical force of Earthquake?

9. Why moment redistribution is not considered in EQ analysis?

10.If a structure has long span or if the cantilever is more than 5m is worth to neglect the vertical force of EQ?

More to come.
  
T.RangaRajan
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thirumalaichettiar
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PostPosted: Fri Apr 01, 2011 9:44 pm    Post subject: Reply with quote

Dear Dr.N.S.Sir,

Really I would like to thank you for the immediate response.I am adding my reply in addition to your valuable replies.

I am expecting more response from seniors like Dr.Kunal, Dr.rajaman, Er.Ibarua ,Er.u.H. Varyani and many more.


1.Which material is good for Seismic?STEEL,CONCRETE,MASONRY AND TIMBER etc.

Desirable features of structural  materials for earthquake are:

      a. ductility.
      b. high strength-weight ratio
      c. homogeneity,
      d. ease in making full strength connections.
Based on the above the following are listed:

High rise Medium rise Low rise
best 1-steel
2-in-situ RC
1-steel
2-In situ RC
1-steel
2-In-situ RC
3-good precast concrete3-seel
4-precast concrete
5-good Rein.Masonry
4-precast concrete
5-good rein.masonry
6-good precast concrete
worst 7-primitive

In addition to the above timber is a light weight but is very easily destroyed by fire and fungus growth.

The material chosen should be easy to construct and maintainable.  Even though  steel is a preferred material the design of connection and the very complex nature specially the welding makes it vulnerable to failure during earth quake.


2.Can we use other than steel like fiberglass bars(GRP), aluminium bars etc as steel reinforcement?

The fiber glass rein and other bars having no ductility and are tensile nature can not be used since the desirable quality of reinforcement is the ductility. That is reason the code specifies that the bars having ductility less than 14.5% are not accepted.

I will be sending the other replies soon.

The other seniors including yourself can correct me if I mislead the sefians.


T.RangaRajan.
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