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mohd atif SEFI Member
Joined: 27 Jul 2014 Posts: 14
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Posted: Sun Aug 10, 2014 11:29 pm Post subject: how to release secondary beam on three of four cantilever |
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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 General Sponsor
Joined: 21 Feb 2008 Posts: 5538 Location: Gaithersburg, MD, U.S.A.
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Posted: Mon Aug 11, 2014 7:55 pm Post subject: Re: how to release secondary beam on three of four cantilev |
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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 SEFI Member
Joined: 27 Jul 2014 Posts: 14
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Posted: Tue Aug 12, 2014 8:49 am Post subject: |
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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 General Sponsor
Joined: 21 Feb 2008 Posts: 5538 Location: Gaithersburg, MD, U.S.A.
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Posted: Tue Aug 12, 2014 8:17 pm Post subject: |
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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 SEFI Member
Joined: 27 Jul 2014 Posts: 14
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Posted: Tue Aug 12, 2014 10:34 pm Post subject: |
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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 General Sponsor
Joined: 21 Feb 2008 Posts: 5538 Location: Gaithersburg, MD, U.S.A.
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Posted: Tue Aug 12, 2014 10:40 pm Post subject: |
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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 General Sponsor
Joined: 24 Nov 2011 Posts: 1408 Location: Cochin
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Posted: Wed Aug 13, 2014 1:18 am Post subject: |
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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 SEFI Member
Joined: 27 Jul 2014 Posts: 14
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Posted: Wed Aug 13, 2014 3:28 pm Post subject: |
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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 General Sponsor
Joined: 24 Nov 2011 Posts: 1408 Location: Cochin
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Posted: Thu Aug 14, 2014 2:20 am Post subject: |
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The STAAD files could not be run due to errors. Please rectify and post again .
E S Jayakumar |
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mohd atif SEFI Member
Joined: 27 Jul 2014 Posts: 14
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Posted: Thu Aug 14, 2014 9:03 am Post subject: |
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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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