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how to release secondary beam on three of four cantilever
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mohd atif
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Joined: 27 Jul 2014
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PostPosted: Sun Aug 10, 2014 11:29 pm    Post subject: how to release secondary beam on three of four cantilever Reply with quote

how to release  secondary beam moment  on  three of four cantilever lined continuously . secondary beam is continuous and i have a sheer doubt which cant beam will support and which one will rest, please clear my doubt   .
while analysing if i release on four cant beams  one of the cant  beam producind 5oo KNm which is very high
plase clear my doubt
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Dr. N. Subramanian
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PostPosted: Mon Aug 11, 2014 7:55 pm    Post subject: Re: how to release secondary beam on three of four cantilev Reply with quote

mohd atif wrote:
how to release  secondary beam moment  on  three of four cantilever lined continuously . secondary beam is continuous and i have a sheer doubt which cant beam will support and which one will rest, please clear my doubt   .
while analysing if i release on four cant beams  one of the cant  beam producind 5oo KNm which is very high
plase clear my doubt

You can't release moments in the software when you have continuous beams. Even when there are SS beams, the detailing should be such that only reactions are transferred. Roughly the BM at the support point of cantilever beam will be WL^2 /2. Based on this you have to decide on the depth of cantilever beam. The depth may  also will depend on the development Length if the cantilever beam is directly supported on column.

Best wishes,
NS
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mohd atif
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PostPosted: Tue Aug 12, 2014 8:49 am    Post subject: Reply with quote

i understand it very well sir, reactions must be transferred from secondary beam to primary beam.  but the problem is  a continuous secondary beam  laid on multiple cantilever.
so ,should i transfer reaction from each beam to cantilever or the stiffness of the beam plays the role in transferring the reaction from secondary beam to primary cant beam, such that few cant beam will act as a secondary beam.  
please clarify the doubt.
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Dr. N. Subramanian
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PostPosted: Tue Aug 12, 2014 8:17 pm    Post subject: Reply with quote

Dear Er Atif,

Yes. You need to transfer the reaction from each beam to the cantilevers.

Best wishes,
NS

mohd atif wrote:
i understand it very well sir, reactions must be transferred from secondary beam to primary beam.  but the problem is  a continuous secondary beam  laid on multiple cantilever.
so ,should i transfer reaction from each beam to cantilever or the stiffness of the beam plays the role in transferring the reaction from secondary beam to primary cant beam, such that few cant beam will act as a secondary beam.  
please clarify the doubt.
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mohd atif
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Joined: 27 Jul 2014
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PostPosted: Tue Aug 12, 2014 10:34 pm    Post subject: Reply with quote

respected sir,
             i tried to release moment from each beam and the results are astonishing.  one of the cantilever beam produces  unusual moment of - -500 KNm . since one of the cantilever was long and the result gave a considerable moment.
and when i changed long cant beam to  propped cant beam  and released secondary beam  at stiffer cantilever beam .the moment produces at cant beams were under 160 KNm
so can we take stiffness as a parameter to judge  release of moment.
please rectify if iam wrong.if u need the staad file to better understand the problem, please let me know


thank you
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Dr. N. Subramanian
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PostPosted: Tue Aug 12, 2014 10:40 pm    Post subject: Reply with quote

Dear Er Atif,

I do not have STAAD. Can you please send me a sketch? Since cantilever is a determinate structure, we do not need computer to solve it.

Making it propped cantilever will completely change it behavior and hence you can not compare it with the results of cantilever.


Best wishes,
NS

mohd atif wrote:
respected sir,
             i tried to release moment from each beam and the results are astonishing.  one of the cantilever beam produces  unusual moment of - -500 KNm . since one of the cantilever was long and the result gave a considerable moment.
and when i changed long cant beam to  propped cant beam  and released secondary beam  at stiffer cantilever beam .the moment produces at cant beams were under 160 KNm
so can we take stiffness as a parameter to judge  release of moment.
please rectify if iam wrong.if u need the staad file to better understand the problem, please let me know


thank you
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es_jayakumar
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PostPosted: Wed Aug 13, 2014 1:18 am    Post subject: Reply with quote

Dear Atif,

You may post the STAAD editor also, along with the sketch, for better understanding of the problem.

E S Jayakumar
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mohd atif
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PostPosted: Wed Aug 13, 2014 3:28 pm    Post subject: Reply with quote

thanks  everyone for replying,
please check staad file , skecth



file name staad corresponds to the sketch


and file name staad 2 beam 339 contains long cant beam with similar problem
the long cant beam is  about 15 feet length
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es_jayakumar
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PostPosted: Thu Aug 14, 2014 2:20 am    Post subject: Reply with quote

The STAAD files could not be run due to errors. Please rectify and post again .

E S Jayakumar
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mohd atif
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PostPosted: Thu Aug 14, 2014 9:03 am    Post subject: Reply with quote

respected jayakumar,
              its working fine , i did analysed again. it may be due to winrar file. it may work if u extract the file
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