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Er.shivani SEFI Member
Joined: 29 May 2018 Posts: 13

Posted: Mon Aug 07, 2023 12:30 pm Post subject: rectangular hollow section purlins 


hii sir/mam,
I am designing a rectangular hollow section purlin.
what formula should we used to find plastic section modulus required to initially assume a section? can we use the formula given by gaylord as attached.
I cannot find any reference where clear design procedure of rectangular hollow section purlins is given as per IS800, it would be of great help if anyone could share the design procedure they follow to design SHS or RHS purlins.
Thanks in advance.
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R_Shenoy SEFI Member
Joined: 20 Mar 2012 Posts: 11

Posted: Tue Aug 08, 2023 12:30 pm Post subject: rectangular hollow section purlins 


Please download tech literature for tata hollow sections. It contains section properties, allowable stresses, etc.
On Tue, 8 Aug, 2023, 15:53 Er.shivani, <forum@sefindia.org (forum@sefindia.org)> wrote:
Quote:  hii sir/mam,
I am designing a rectangular hollow section purlin.
what formula should we used to find plastic section modulus required to initially assume a section? can we use the formula given by gaylord as attached.
I cannot find any reference where clear design procedure of rectangular hollow section purlins is given as per IS800, it would be of great help if anyone could share the design procedure they follow to design SHS or RHS purlins.
Thanks in advance.
Download Attachments:
IMG_20230807_174848.jpg

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Binoy Bhuson Saha SEFI Regulars
Joined: 30 Oct 2009 Posts: 31

Posted: Wed Aug 09, 2023 6:30 am Post subject: rectangular hollow section purlins 


In my opinion instead of retangular hollow section you may use pipe section.If the purlin is used for roof top composit section suitable channel section braced with bend rod may be used.
On Tuesday, 8 August, 2023 at 03:52:18 pm IST, Er.shivani <forum@sefindia.org> wrote:
hii sir/mam,
I am designing a rectangular hollow section purlin.
what formula should we used to find plastic section modulus required to initially assume a section? can we use the formula given by gaylord as attached.
I cannot find any reference where clear design procedure of rectangular hollow section purlins is given as per IS800, it would be of great help if anyone could share the design procedure they follow to design SHS or RHS purlins.
Thanks in advance.
Attachments:
http://www.sefindia.org/forum/files/img_20230807_174848_156.jpg
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durai_sundaram General Sponsor
Joined: 07 Apr 2020 Posts: 3

Posted: Wed Aug 09, 2023 7:30 am Post subject: rectangular hollow section purlins 


The same formula is given in Page 477 ( design of beams) in the book " Design of steel structures  Limit state method " by Dr. N.subramaniam.
M.Durai
On Wed, Aug 9, 2023 at 12:09â€¯PM Binoy Bhuson Saha <forum@sefindia.org (forum@sefindia.org)> wrote:
Quote:  In my opinion instead of retangular hollow section you may use pipe section.If the purlin is used for roof top composit section suitable channel section braced with bend rod may be used.
On Tuesday, 8 August, 2023 at 03:52:18 pm IST, Er.shivani wrote:
hii sir/mam,
I am designing a rectangular hollow section purlin.
what formula should we used to find plastic section modulus required to initially assume a section? can we use the formula given by gaylord as attached.
I cannot find any reference where clear design procedure of rectangular hollow section purlins is given as per IS800, it would be of great help if anyone could share the design procedure they follow to design SHS or RHS purlins.
Thanks in advance.
Attachments:
http://www.sefindia.org/forum/files/img_20230807_174848_156.jpg

Posted via Email


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Manas M Ghosh Bronze Sponsor
Joined: 26 Feb 2010 Posts: 66

Posted: Wed Aug 09, 2023 8:11 am Post subject: Zp of RHS, SHS 


The Values of Zp for RHS, SHS are available in Pages 796796 of the book Design of Steel Structures by Dr N Subramaniun.
Regards
MMGhosh


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mmg SEFI Member
Joined: 18 Jul 2009 Posts: 5

Posted: Wed Aug 09, 2023 8:30 am Post subject: rectangular hollow section purlins 


The Values of Zp for RHS, SHS are available in Pages 796796 of the book Design of Steel Structures by Dr N Subramaniun.
Regards
MMGhosh
On Wed, Aug 9, 2023 at 12:42â€¯PM Binoy Bhuson Saha <forum@sefindia.org (forum@sefindia.org)> wrote:
Quote:  In my opinion instead of retangular hollow section you may use pipe section.If the purlin is used for roof top composit section suitable channel section braced with bend rod may be used.
On Tuesday, 8 August, 2023 at 03:52:18 pm IST, Er.shivani wrote:
hii sir/mam,
I am designing a rectangular hollow section purlin.
what formula should we used to find plastic section modulus required to initially assume a section? can we use the formula given by gaylord as attached.
I cannot find any reference where clear design procedure of rectangular hollow section purlins is given as per IS800, it would be of great help if anyone could share the design procedure they follow to design SHS or RHS purlins.
Thanks in advance.
Attachments:
http://www.sefindia.org/forum/files/img_20230807_174848_156.jpg

Posted via Email


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svgkrao SEFI Member
Joined: 04 Nov 2011 Posts: 2

Posted: Wed Aug 09, 2023 8:30 am Post subject: rectangular hollow section purlins 


Dear all,
As per IS 800, RHS /SHS come under closed section. I designed RHS 150x100x3.6mm for 7.5m span purlins as per IS 800 last year and executed the project. The owner and erection contractor appreciated RHS pulins after seeing some issues of Z purlins in surrounding sites.
On Wed, 9 Aug 2023, 12:49 Binoy Bhuson Saha, <forum@sefindia.org (forum@sefindia.org)> wrote:
Quote:  In my opinion instead of retangular hollow section you may use pipe section.If the purlin is used for roof top composit section suitable channel section braced with bend rod may be used.
On Tuesday, 8 August, 2023 at 03:52:18 pm IST, Er.shivani wrote:
hii sir/mam,
I am designing a rectangular hollow section purlin.
what formula should we used to find plastic section modulus required to initially assume a section? can we use the formula given by gaylord as attached.
I cannot find any reference where clear design procedure of rectangular hollow section purlins is given as per IS800, it would be of great help if anyone could share the design procedure they follow to design SHS or RHS purlins.
Thanks in advance.
Attachments:
http://www.sefindia.org/forum/files/img_20230807_174848_156.jpg

Posted via Email


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Er.shivani SEFI Member
Joined: 29 May 2018 Posts: 13

Posted: Wed Aug 09, 2023 8:52 am Post subject: rectangular hollow section purlins 


thanks all for your reply
sir, my question is,
as in case of channel or i section purlins we have a formula (as attached previously) to get plastic section modulus required and from there we assume a suitable section whose plastic modulus is greater than the required value.
In the same way do we have a formula to find required section modulus for square/ rectangular hollow sections.


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Manas M Ghosh Bronze Sponsor
Joined: 26 Feb 2010 Posts: 66

Posted: Wed Aug 09, 2023 9:26 am Post subject: Zp of RHS, SHS 


Sir,
Can you share me the basis of the formula?
Zp of RHS and SHS are also listed in IS 4239.
Regards
MMGhosh


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Er.shivani SEFI Member
Joined: 29 May 2018 Posts: 13

Posted: Wed Aug 09, 2023 9:39 am Post subject: rectangular hollow section purlins 


the formula is given for channel and i section purlins in "Design of steel structures:Limit state method,N subramanian "
it is given on page no 480 equation 10.63
also it is used in example 10.11 of the book on page no 493494


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