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HEXOGONAL STEEL ROOF
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thirumalaichettiar
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PostPosted: Thu Apr 09, 2020 8:24 am    Post subject: Reply with quote

Dear Er.Prabhar,
I watched. Please be informed that I already having your RCC design software but need only Steel but the price seems to be very high compared to RCC. I am thinking since I do not encounter too many steel designs which I am trying with STAADPRO and NISA DESIGN STUIO.

Anyway thanks for your kind information.

With Best Regards.

T.RangaRajan
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thirumalaichettiar
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PostPosted: Thu Apr 16, 2020 5:13 am    Post subject: Reply with quote

Dear Sefians, Noticed that there are 509 viewers but not got any solid guidance except from Dr.N.S. I do not know whether they do not want to share or not.
Anyway expecting some guidance.
I attach the 3 View  as JPEG as well as PDF format of the roof truss from STAADPRO for more suggestions.


T.RangaRajan.



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Dr. N. Subramanian
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PostPosted: Thu Apr 16, 2020 11:07 pm    Post subject: Reply with quote

thirumalaichettiar wrote:
Dear Sefians, Noticed that there are 509 viewers but not got any solid guidance except from Dr.N.S. I do not know whether they do not want to share or not.
Anyway expecting some guidance.
I attach the 3 View  as JPEG as well as PDF format of the roof truss from STAADPRO for more suggestions.


T.RangaRajan.

Dear Er RangaRajan

There is no need to extend the trusses beyond the top ring. This will also reduce the congestion at the top.

For wind loading some guidance may be got from my Space Structures book.

Warm regards
Subramanian
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thirumalaichettiar
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PostPosted: Fri Apr 17, 2020 4:48 am    Post subject: Reply with quote

Dear Dr.Subramaniam/Sir,
Thanks for your guidance. Still I am having doubt on the central support and also for continuity I proposed. But I will try as per your suggestion.
I took the wind load as per IS code 675-3. Since it is open structure the dead and wind load will not be designing criteria.

Modified the same with the bottom bracing as shown now.

Thanks,
T.RangaRajan.



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tosifsayyed
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PostPosted: Fri Apr 17, 2020 9:25 am    Post subject: Reply with quote

Dear RangaRajan Sir,
     This is the same concept what I was trying to suggest you. For central portion I will still suggest you the same. Try continuing two trusses which are crossing is other orthogonal. Then the central circular piece will rest on these trusses and other secondary trusses will rest on these circular truss on one side and on column on other sides. Please find attached image.
I hope this will be useful to you.
    In image only peripheral concrete beam and trusses are shown. Purlins are not shown. Rest of your arrangement is okay for me.

Regards



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Tosif Sayyed
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thirumalaichettiar
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PostPosted: Fri Apr 17, 2020 2:12 pm    Post subject: Reply with quote

tosifsayyed wrote:
Dear RangaRajan Sir,
     This is the same concept what I was trying to suggest you. For central portion I will still suggest you the same. Try continuing two trusses which are crossing is other orthogonal. Then the central circular piece will rest on these trusses and other secondary trusses will rest on these circular truss on one side and on column on other sides. Please find attached image.
I hope this will be useful to you.
    In image only peripheral concrete beam and trusses are shown. Purlins are not shown. Rest of your arrangement is okay for me.

Regards

Thanks.
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Dr. N. Subramanian
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PostPosted: Fri Apr 17, 2020 8:40 pm    Post subject: Reply with quote

Dear Er Rangarajan,
This is a 3D structure and act like a dome. No need to join the trusses at the top. The top circular truss will tie all the trusses springing from the bottom truss. If you analyse the same you will realize. See the paper, I sent, which is a 60 m dome. No support is there at the centre. While constructing you need supports for the top (conpression) truss. But after all the  radual(rib) trusses are connected you may remove it and it will as as a 3D ribbed dome.

As a preliminary design, You may give the ribs as single members and get the results. The truss members can be designed, based on the BM, assuming a depth, the size can be determined from the maximum axial force= BM/assumed depth.

Warm regards
Subramanian
thirumalaichettiar wrote:
Dear Dr.Subramaniam/Sir,
Thanks for your guidance. Still I am having doubt on the centraadl support and also for continuity I proposed. But I will try as per your suggestion.
I took the wind load as per IS code 675-3. Since it is open structure the dead and wind load will not be designing criteria.

Modified the same with the bottom bracing as shown now.

Thanks,
T.RangaRajan.


Last edited by Dr. N. Subramanian on Sat Apr 18, 2020 2:29 pm; edited 1 time in total
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thirumalaichettiar
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PostPosted: Sat Apr 18, 2020 4:23 am    Post subject: Reply with quote

Dear Dr.N.S/Sir,
I will follow your guidance and try to have the central rib without connecting the trusses at the center.
Thanks.

T.RangaRajan.
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spsvasan
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PostPosted: Sat Apr 18, 2020 4:34 am    Post subject: Reply with quote

thirumalaichettiar wrote:
Dear Sefians, Noticed that there are 509 viewers but not got any solid guidance except from Dr.N.S. I do not know whether they do not want to share or not.
Anyway expecting some guidance.
I attach the 3 View  as JPEG as well as PDF format of the roof truss from STAADPRO for more suggestions.


T.RangaRajan.



Dear Er.Rangarajan

The following are my suggestions:


  1. I agree with Dr.NS's suggestion that the radial girder need not be extended beyond the inner ring girder. The inner ring girder will be subject to high compressive stresses apart from other stresses
  2. Was there an improvement in the structural behaviour due to addition of cross bracing? I felt that there will not be significant improvement due to cross bracing. I have not checked
  3. Regarding erection my suggestion is to erect a 29' high temporary tower at the centre; placing the inner octoganal gider over the same, Next the outer octangonal girder may be erected over the columns. The radial girders may be fabricated, erected, connected to the inner and outer octagonal girders and temporarily propped. After all the girders have been erected and joined properly the temporary supports may be removed
  4. I hope the deflections are within safe limits

Regards
S.P.Srinivasan
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thirumalaichettiar
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PostPosted: Sun Apr 19, 2020 12:19 pm    Post subject: Reply with quote

Dear Er.S.P.S,


Thanks for your valuable points.  I will follow the steps that as you pointed and check the other notes.

Thanks,

With Warm Regards,

T.Rangarajan.
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