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Hanging Stair

 
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ibu_4_u
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PostPosted: Mon Feb 24, 2014 11:37 am    Post subject: Hanging Stair Reply with quote

Dear All,

I have to designed an Open newel Staircase which do not have any support at midlanding, the stair have the only support at 1st floor beam & next directly on 2nd floor beam,

The stair will be fabricated with steel structure. as shown in the Attachment

Please suggest any arrangement of stair or any reference design material with such stair case.

The floor to floor height is 10' feet



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umeshrao
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Joined: 23 Aug 2010
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Location: Bangalore, India

PostPosted: Mon Feb 24, 2014 12:27 pm    Post subject: Re: Hanging Stair Reply with quote

ibu_4_u wrote:
Dear All,
I have to designed an Open newel Staircase which do not have any support at midlanding, the stair have the only support at 1st floor beam & next directly on 2nd floor beam,
The stair will be fabricated with steel structure. as shown in the Attachment
Please suggest any arrangement of stair or any reference design material with such stair case.
The floor to floor height is 10' feet


This type of stairs are normally termed as free standing staircase. To get forces in the free standing stairs refer Reynold's Handbook. Though book's name is RC designers handbook, It deals with all types of stairs and you will be able to analyze and find forces.
Please keep in mind that since it is three dimensional analysis torsion has to be accounted for and hence closed rectangular, square or box sections.
Regards
Umesh Rao
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k.gangadharan
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PostPosted: Mon Feb 24, 2014 2:22 pm    Post subject: Reply with quote

dear er ibu_4_u

sub: For design of free standing stairs , there is one book by name

'Analysis & Design of Staircases by M.Y.H Bangashangash
.& T. Bangash. This

book ,you can find in the references given under chapter on staircases in the new

book by Dr. N. Subramanian on Design of reinforced concrete structures.

This book by Bangash is a foreign publication and costs about Rs 16000/- and

you can find it in the website 'fliopcart.com'.

As Er.UmeshRao  has pointed out, you can find formula for design of

freestandingstaircases in Reynold's handbook. It is a tree dimensional analysis

and design has to be carried out for BM and torsion in all three axes. The

formula given in Reynold's handbook is not easy to understand.

Bangash 's book is the only book that deals with  analysis & design

of free standing staircases including all types of  other staircases, in my

knowledge.

regards

Gangadharan.K
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Jayant Lakhlani
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Joined: 26 Jan 2003
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Location: Rajkot, Gujarat, India

PostPosted: Mon Feb 24, 2014 4:38 pm    Post subject: Hanging Stair Reply with quote

Also proper fixity for all six degrees of freedom is mandatory at supports. Many a times, in the analysis, the supports are modelled as fixed but due to lack of proper detailing, this is not actually achieved at site, resulting in to failures.

Regards.

Jayant Lakhlani
For
Lakhlani Associates

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umeshrao
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Joined: 23 Aug 2010
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PostPosted: Tue Feb 25, 2014 5:34 am    Post subject: Re: Hanging Stair Reply with quote

Jayant Lakhlani wrote:
Also proper fixity for all six degrees of freedom is mandatory at supports. Many a times, in the analysis, the supports are modelled as fixed but due to lack of proper detailing, this is not actually achieved at site, resulting in to failures.Regards.
Jayant Lakhlani For Lakhlani Associates
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Dear Mr. Lakhlani,
Supports may be hinged or fixed. It is three dimensional analysis of a horizontal portal. If you study various papers written by Saunter and others and if write equation stability can be achieved by considering hinged support.
Having designed,detailed and conducted load test on all constructed free standing stairs [about 400 and above since 1973 or so] I can confidently say that both edge condition are acceptable, theoretically and in practice and behaved extremely well.
While referring Reynolds handbook for freestanding stairs [ in the Indian Edition published by Rupa & Co ] printing mistake has crept in. Hence be careful and verify before use. Multiplier 'a' term is missing.
Regards
Umesh Rao
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Dr. N. Subramanian
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PostPosted: Tue Feb 25, 2014 1:50 pm    Post subject: Re: Hanging Stair Reply with quote

Dear Er Umesh Rao,

I have also designed only one free standing staircase. It is heartening to note that you designed more than 400 of them. Great. I think it is a record. Congrats.


It will be useful to other engineers if you could give the page number and the equation which is wrong and also the correct equation.

Complete design, detailing and construction of a free standing staircase is available in the  ICJ paper by Er Karunakar Rao in May 1983.

Warm regards
Subramanian
Posted via Email[/quote]
Dear Mr. Lakhlani,
Supports may be hinged or fixed. It is three dimensional analysis of a horizontal portal. If you study various papers written by Saunter and others and if write equation stability can be achieved by considering hinged support.
Having designed,detailed and conducted load test on all constructed free standing stairs [about 400 and above since 1973 or so] I can confidently say that both edge condition are acceptable, theoretically and in practice and behaved extremely well.
While referring Reynolds handbook for freestanding stairs [ in the Indian Edition published by Rupa & Co ] printing mistake has crept in. Hence be careful and verify before use. Multiplier 'a' term is missing.
Regards
Umesh Rao[/quote]
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umeshrao
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Joined: 23 Aug 2010
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PostPosted: Wed Feb 26, 2014 10:31 am    Post subject: Re: Hanging Stair Reply with quote

quote="Dr. N. Subramanian"]Dear Er Umesh Rao,
I have also designed only one free standing staircase. It is heartening to note that you designed more than 400 of them. Great. I think it is a record. Congrats.
It will be useful to other engineers if you could give the page number and the equation which is wrong and also the correct equation.
Complete design, detailing and construction of a free standing staircase is available in the  ICJ paper by Er Karunakar Rao in May 1983.
Warm regards Subramanian Posted via Email[/quote]

Dear Dr. Subramanian,
First time probably 1973 or 74, when we designed free standing stairs,I was thrilled to see the elegant, beautiful piece performing. That was for industrial project office building.
Subsequently since mid 80's any chance to provide free standing stairs I use to suggest. Obviously there has to be atleast one more stairs for emergency evacuation such as fire and not dependent on this free standing.
Let me see if I have some photos of the projects. I will post different types of free standing stairs using different materials.
Regards
Umesh Rao
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SS.Narayanan
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Joined: 25 Jan 2013
Posts: 4
Location: Chennai

PostPosted: Thu Feb 27, 2014 5:15 am    Post subject: Reply with quote

Dear Sirs,

       Thanks for sharing valuable infos. I would like to know which book of Indian author covers most of the designs of various types of staircases. Also, am unable to locate the "ICJ paper by Er Karunakar Rao in May 1983" in google, I guess that paper is not available in Elsevier also. Can anyone help me by forwarding this journal to my mail i.d; zenssn@gmail.com


Thanks & rgds
SS.Narayanan
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