Discussion Groups

Robot Structural Analysis

Reply
Member
zameerajmal
Posts: 4
Registered: ‎06-18-2012
Accepted Solution

STEEL DESIGN - INSTABLE SECTION - SLENDERNESS - Beam design under ULS

705 Views, 5 Replies
06-18-2012 02:47 AM

Hello,

 

I have generated 3D frame using RSA 2013 professional. When i verify the rafter beams under ultimate limit state, the results shown are instable. And when optimized under ULTIMATE it provides very large dimension beams. whereas when i used SERVICEABILITY METHOD, it is fine. 

 

Please help me, how to verify beams in 3D generator. 

 

Please find attached 3D design file

 

Kind regards,

 

Ajmal

Please use plain text.
Member
zameerajmal
Posts: 4
Registered: ‎06-18-2012

Re: 3D Frame Generator- Beam design under ULS

06-18-2012 02:49 AM in reply to: zameerajmal

I ain't able to attach rsa file, please help me

 

find result snaps for reference

 

why can't i design beam under ULS 

Please use plain text.
Product Support
Artur.Kosakowski
Posts: 4,777
Registered: ‎12-17-2010

Re: 3D Frame Generator- Beam design under ULS

06-18-2012 03:06 AM in reply to: zameerajmal

ULS and SLS check are two different verifications,. As far as I can see the problem you have got is the exceeded slenderness limit. Looking at the buckling Z part you can see that unrestrained buckling length for 140 section is over 14m which way  too long weak the axes if this section. Have you set the buckling parameters correctly?



Artur Kosakowski
Please use plain text.
Member
zameerajmal
Posts: 4
Registered: ‎06-18-2012

Re: STEEL DESIGN - INSTABLE SECTION - SLENDERNESS - Beam design under ULS

06-18-2012 03:14 AM in reply to: zameerajmal

I haven't set the paramters. I am a learner, student. how to set, will you please help me

 

Thanks

Ajmal

Please use plain text.
Member
zameerajmal
Posts: 4
Registered: ‎06-18-2012

Re: 3D Frame Generator- Beam design under ULS

06-18-2012 03:16 AM in reply to: Artur.Kosakowski

The beam length is 7.11 m

 

bay width is 14 m

Please use plain text.
Product Support
Artur.Kosakowski
Posts: 4,777
Registered: ‎12-17-2010

Re: 3D Frame Generator- Beam design under ULS

06-18-2012 03:20 AM in reply to: zameerajmal

Assuming it is a 2 span beam then either you set buckling Z (and LTB) coefficients as 0.5L or you should define an intermediate restrain at this point and then set these coefficients as 1.0L  for each of the spans.

 

If you find your post answered press the Accept as Solution button please. This will help other users to find solutions much faster. Thank you.

 

 



Artur Kosakowski
Please use plain text.