STRUCTURAL ENGINEERING FORUM OF INDIA [SEFI]

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

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.

R_Shenoy · SEFI Member Joined: 20 Mar 2012 Posts: 11

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:

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

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

Posted via Email

durai_sundaram · General Sponsor Joined: 07 Apr 2020 Posts: 3

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:

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

The Values of Zp for RHS, SHS are available in Pages 796-796 of the book Design of Steel Structures by Dr N Subramaniun.

Regards
MMGhosh

mmg · SEFI Member Joined: 18 Jul 2009 Posts: 5

The Values of Zp for RHS, SHS are available in Pages 796-796 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:

svgkrao · SEFI Member Joined: 04 Nov 2011 Posts: 2

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:

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

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.

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

Sir,

Can you share me the basis of the formula?

Zp of RHS and SHS are also listed in IS 4239.

Regards
MMGhosh

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

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 493-494