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Sudhakaran General Sponsor
Joined: 16 Jul 2013 Posts: 240 Location: Kannur

Posted: Thu Sep 05, 2013 9:01 am Post subject: 


Dear,
STAAD will design for Mz and My with torsion but can not done at a time. You do a trial design with both case and combine it and verify manually.
Check the horizontal load transfer mechanism is it torsion? (if load not acts at exact centre of the depth). If so try by applying tosion in the form of uniform moment.
Design using column design may not economical and the shear and torsion design may a problem
These are all my suggestions since i never come across such a problem.
Regards,
Sudhakaran.
ibu_4_u wrote:  Dear Sudhakaran Sir,
i believe that staad will design beam for moment in Mz direction and Moment in Mx direction, for that reason i had applied the torsion design parameter also in staad for designing beam.
but as per in my case i am applying the UDL load on beam in Fy direction and Fx direction, as it is applied on the center line of the beam the torsion effect is not much coming in the picture. 


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sakumar79 ...
Joined: 18 Apr 2008 Posts: 682

Posted: Thu Sep 05, 2013 9:26 am Post subject: 


Dear Sir,
To design the beam with horizontal load acting on it, what I do in case of simple structures is
1. Design the beam with only vertical loads on it.
2. Design the beam separately with width and depth values interchanged and apply the horizontal load as vertical load.
3. The max. Ast of top and bottom steel from second step is considered, divided by two and added as extra reinforcement bar(s) at the four corners of the beam designed from point 1.
Above methodology may be a bit more complicated to apply in case of complex structures
However, if I understood you correctly from the first post, you are designing this for self supported curved roofing (without truss). In that case, you will probably also have a gutter. If so, you can use the gutter base slab as a deep beam (base slab thickness will be width of beam and gutter width+end wall thickness+tie beam thickness will be depth of beam) for taking the horizontal thrust. Provide detailing to anchor the gutter slab bars at the columns.
Yours sincerely,
Arunkumar 

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Sudhakaran General Sponsor
Joined: 16 Jul 2013 Posts: 240 Location: Kannur

Posted: Thu Sep 05, 2013 12:43 pm Post subject: 


Dear sir,
I seems same methodology(1&2) has been used in staad. But why third step is used ie, Ast divide by 2
sakumar79 wrote:  Dear Sir,
To design the beam with horizontal load acting on it, what I do in case of simple structures is
1. Design the beam with only vertical loads on it.
2. Design the beam separately with width and depth values interchanged and apply the horizontal load as vertical load.
3. The max. Ast of top and bottom steel from second step is considered, divided by two and added as extra reinforcement bar(s) at the four corners of the beam designed from point 1.
Above methodology may be a bit more complicated to apply in case of complex structures
However, if I understood you correctly from the first post, you are designing this for self supported curved roofing (without truss). In that case, you will probably also have a gutter. If so, you can use the gutter base slab as a deep beam (base slab thickness will be width of beam and gutter width+end wall thickness+tie beam thickness will be depth of beam) for taking the horizontal thrust. Provide detailing to anchor the gutter slab bars at the columns.
Yours sincerely,
Arunkumar 


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sakumar79 ...
Joined: 18 Apr 2008 Posts: 682

Posted: Thu Sep 05, 2013 4:25 pm Post subject: 


Dear Sir,
Half the Ast is taken to calculate required Area/diameter of 1 bar which will be provided on each four corner. For example, if we get max Ast of 200 sqmm in the horizontal load case, we need 100 sqmm per bar for which one 12 mm dia bar should be added to each corner. Here, we need to remember that in the case of design for the horizontal load, Ast from staad is shown as "Top" and "Bottom" reinforcement but should be interpreted as "Left Side Ast" and "Right side Ast" in the actual beam. Hence, this reinforcement can also be given in the form of skin reinforcement in case of deep beam.
Yours sincerely
Arunkumar 

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ibu_4_u General Sponsor
Joined: 14 Sep 2009 Posts: 22

Posted: Thu Sep 05, 2013 6:30 pm Post subject: 


Dear arunkumar Sir,
i am designing this for self supported Curved roofing (without tuss) spanning for 36m,
and i am also having RCC gutter, which is running continues through out the length,
One of my colleague has also given the same advice as suggested by you, considering the gutter with beam as a deep beam.
At present i am following the same advice as given by you all.
Thank you very much for your recommendations and advices.
Kind Regards
Ibrahim vepari 

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Sudhakaran General Sponsor
Joined: 16 Jul 2013 Posts: 240 Location: Kannur

Posted: Fri Sep 06, 2013 3:26 am Post subject: 


Dear Arunkumar sir,
Thank you sir.
sakumar79 wrote:  Dear Sir,
Half the Ast is taken to calculate required Area/diameter of 1 bar which will be provided on each four corner. For example, if we get max Ast of 200 sqmm in the horizontal load case, we need 100 sqmm per bar for which one 12 mm dia bar should be added to each corner. Here, we need to remember that in the case of design for the horizontal load, Ast from staad is shown as "Top" and "Bottom" reinforcement but should be interpreted as "Left Side Ast" and "Right side Ast" in the actual beam. Hence, this reinforcement can also be given in the form of skin reinforcement in case of deep beam.
Yours sincerely
Arunkumar 


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pravin_shirsath ...
Joined: 23 Jan 2011 Posts: 65

Posted: Fri Sep 06, 2013 4:19 am Post subject: 


In addition to sakumar79,
Workout moment capacity for My and Mz for Ast provided
& check interaction ratio for bending.
considering beam element for biaxial moment will give you heavy design compare to column design,but it is safe and easy for calculation for moment and shear. 

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uhvaryani General Sponsor
Joined: 21 May 2008 Posts: 256

Posted: Fri Sep 06, 2013 7:21 am Post subject: Design of beam in plan bending direction that is My dirctn 


Dear friends,
For biaxial bending of beams,we may refer to.
1.chapter 6 of book,Biaxial bending of reinforced concrete
members,by u.h.varyani,and
2.Sinha,S.N.and Banerjee,I. Design aids for R.C.rectangular
beams subjected to biaxial moments.The Indian Concrete
Journal,May,1994.
with best wishes and regards,
uhvaryani
Posted via Email 

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ibu_4_u General Sponsor
Joined: 14 Sep 2009 Posts: 22

Posted: Mon Sep 09, 2013 9:22 am Post subject: 


Dear Uhvaryani Sir,
I got one book name "Design aids for Limit state design of Reinforced Concrete Members" by U.H.Varyani & A.Radhaji.
I also got the worked out example in this book, as per my requirement.
Thanking you sir, for your references.
Thanks & Regards,<o></o>
Ibrahim Vepari 

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