www.sefindia.org

STRUCTURAL ENGINEERING FORUM OF INDIA [SEFI]

 Forum SubscriptionsSubscriptions DigestDigest Preferences   FAQFAQ   SearchSearch   MemberlistMemberlist   UsergroupsUsergroups  RegisterRegister FAQSecurity Tips FAQDonate
 ProfileProfile   Log in to check your private messagesLog in to check your private messages   Log in to websiteLog in to websiteLog in to websiteLog in to forum 
Warning: Make sure you scan the downloaded attachment with updated antivirus tools  before opening them. They may contain viruses.
Use online scanners
here and here to upload downloaded attachment to check for safety.

sub: Castellated steel beams
Goto page 1, 2  Next
 
Post new topicReply to topic Thank Post    www.sefindia.org Forum Index -> SEFI General Discussion
View previous topic :: View next topic  
Author Message
k.gangadharan
General Sponsor
General Sponsor


Joined: 01 Apr 2008
Posts: 204

PostPosted: Sun Jul 28, 2013 3:10 pm    Post subject: sub: Castellated steel beams Reply with quote

To experts of steel structures in sefi


Can we design castellated steel beams as per limit state design code BIS 800- 2007. As per new code of limit state design the web also is considered in taking part in bending compression and bending tension.

Another problem is Plastic modulus is not available for castellated sections in the code or in any other book.What about lateral stability of castellated sections.

We have a span of 14 meters for beams using a metal deck flooring Since manufacture of beams are limited to 12 meter spans , we have to go for splicing of flanges and web. Is welding advisable in place of splicing.

Suggestions are requested from Dr. subramanian or other experts who have experience in

designing such structures


thanks & regards


K.Gangadharan

Structural consultant

SEFI general sponsor

Posted via Email
Back to top
View user's profile Send private message
N. Prabhakar
General Sponsor
General Sponsor


Joined: 25 Apr 2009
Posts: 435

PostPosted: Mon Jul 29, 2013 5:19 am    Post subject: Reply with quote

Dear Er. Gangadharan,

The design of castallated beams as per IS 800 : 2007, using ISMB and ISMC sections, is included in the spreadsheets of the software 'STeelDesign' developed by me.  For details of the software, please my website: www.steeldesignspreadsheets.com which contains two demo videos also.

With best wishes,

Yours truly,

N. Prabhakar
Chartered Structural Engineer
Vasai (E)

Mobile: 9322199254
Back to top
View user's profile Send private message
k.gangadharan
General Sponsor
General Sponsor


Joined: 01 Apr 2008
Posts: 204

PostPosted: Mon Jul 29, 2013 6:54 am    Post subject: Reply with quote

dear Er. prabhakaran

You have mentioned about the possibility of using castellated sections
for design of beams using Limit state design of structures .What about the splicing of web and flanges  since the spans are 14 meters  and sections are moulded  for 12 meters only. Web splices takes two much space and in castellated sections is it possible to provide web splicing . The other alternative is welding. Kindly comment on this.

regards

K. Gangadharan
structyural consultant
Sefi general sponsor
Back to top
View user's profile Send private message
N. Prabhakar
General Sponsor
General Sponsor


Joined: 25 Apr 2009
Posts: 435

PostPosted: Mon Jul 29, 2013 1:42 pm    Post subject: Reply with quote

Dear Er. Gangadharan,

Regarding your query on splice connections in castellated beams, I would like to write the following:

1. The splice connection in flanges is simialr to those in any other typical I- beam.  The connection is to be designed for bending moment acting on the beam at the splice location. The splice plate can be either bolted or welded to suit.

2. Regarding splice connection of web, firstly the castellations on both sides of the splice joint is to to be completely filled with suitably shaped plates of same thickness as the web, by welding.    The web splice plates shall be provided on both sides of the web, and are to be designed to resist shear only acting on the beam at the splice location.  The connection is to be by site welding all round the splice plates before erection.  The height of the splice plate should be to the full depth of the castellated beam that is possible i.e depth between fillets of the beam, and allowing for the weld size.  As the connection is designed for shear only, the width of splice plate will not be big.

I trust you will find the above information useful.

With best wishes,

N. Prabhakar
Back to top
View user's profile Send private message
N. Prabhakar
General Sponsor
General Sponsor


Joined: 25 Apr 2009
Posts: 435

PostPosted: Mon Jul 29, 2013 2:08 pm    Post subject: Reply with quote

Dear Er. Gangadharan,

I would like to add further that the vertical welds of web splice plates should be in the width of web plate between the castellations, and not on the filled up plates of the castellations.  This would govern the width of the web splice plates.

N. Prabhakar
Back to top
View user's profile Send private message
vnacharya
General Sponsor
General Sponsor


Joined: 08 Nov 2009
Posts: 11
Location: CHENNAI

PostPosted: Mon Jul 29, 2013 5:32 pm    Post subject: sub: Castellated steel beams Reply with quote

Thank you sir.

Regards,                            
Vishnu

"k.gangadharan" <forum@sefindia.org> wrote:

Quote:
To experts of steel structures in sefi


Can we design castellated steel beams  as per limit state design code BIS 800- 2007. As per new code of limit state design the web also is considered in taking part in bending compression and bending tension.

Another  problem is  Plastic modulus is not available  for castellated sections  in the code or in any other book.What about lateral stability of castellated sections.

We have a span of 14 meters for beams using a metal deck flooring Since manufacture of beams are limited to 12 meter spans , we have to go for splicing of flanges and web. Is welding advisable in place of  splicing.

Suggestions are requested from Dr. subramanian or other experts who have experience in

designing such structures


thanks & regards


K.Gangadharan

Structural consultant

SEFI general sponsor








Posted via Email
Back to top
View user's profile Send private message
mtamil
General Sponsor
General Sponsor


Joined: 07 Apr 2011
Posts: 187

PostPosted: Tue Jul 30, 2013 5:47 am    Post subject: Reply with quote

Dear Sir,

This is a very good observation. I had designed castellated sections in two projects, which are basically gable frames. We went for castellated sections, because, somebody told the management that these sections are economical and were used in previous projects/similar applications. The design is based on the previous version of the code.

Later, I found that, most of the web area is being overlapped by solid web plates for splicing, bracing, base plate, corner plate etc. .... full of plates.

At site it is not looking good.

Only a small portion left in its original look. I feel, if we do value engineering, these sections may become uneconomical, due to increased cutting/welding, difficulties with connections, requirement of additional plates, splicing etc.

I guess, these sections can be used effectively as beams under a deck, where no additional members connecting to it & lateral stability are ensured.

Splicing by full penetration butt weld is a good option. But all such welds shall be subjected to NDT tests such as radiography, to ensure penetration and assured quality.

Looking for others views.
Regards
Tamilarasan


k.gangadharan wrote:
dear Er. prabhakaran

You have mentioned about the possibility of using castellated sections
for design of beams using Limit state design of structures .What about the splicing of web and flanges  since the spans are 14 meters  and sections are moulded  for 12 meters only. Web splices takes two much space and in castellated sections is it possible to provide web splicing . The other alternative is welding. Kindly comment on this.

regards

K. Gangadharan
structyural consultant
Sefi general sponsor
Back to top
View user's profile Send private message
Abishek_Siingh
Bronze Sponsor
Bronze Sponsor


Joined: 18 Nov 2010
Posts: 609
Location: New Delhi

PostPosted: Tue Jul 30, 2013 6:47 am    Post subject: Reply with quote

Two points I noted here:

1. Can't we calculate the plastic modulus manually using basic principles mentioned in any strength of materials book?

2. If you fill the hexagonal gaps in the web by steel plates and weld it won't we get a nearabout homogenous web which can also participate in the resistance of forces and also participate in the calculation of plastic modulus?

_________________
Thank you,
Abishek Siingh

Back to top
View user's profile Send private message
N. Prabhakar
General Sponsor
General Sponsor


Joined: 25 Apr 2009
Posts: 435

PostPosted: Tue Jul 30, 2013 2:52 pm    Post subject: Reply with quote

Dear Sefinas,

I would like to make the following observations on the recent postings on the subject:

1. The fabrication of castallated beams should be undetaken by well experienced fabricators who have the right tools for cutting and welding the web plate.  It should not be done less experienced and small fabricators who do jobs like window grills and gates.  In UK, it is a common practice to provide castallated beams in their industrial projects, and it is well supported by the British Code, design manuals and local fabricators.  I am sure some well known and large fabricators in India can do equally a good job of it.  If the job is done properly, these beams would not look ugly.

2. The plastic modulus of the net castallated section (excluding castallations) can be calculated manually from the fundamentals.

3. It is the practice in UK to fill up the castallations fully with plates of the same thickness as the web, by welding.  This is done only in the castallations at supports and at locations of any concentrated load on the beam, and not at other places of castallations.  Besides filling up with plate, additional vertical stiffeners are provided on both sides of web at these locations to avoid shear failure of web.

With best wishes,

Yours truly,

N. Prabhakar
Chartered Structural Engineer
Vasai (E)
Back to top
View user's profile Send private message
mtamil
General Sponsor
General Sponsor


Joined: 07 Apr 2011
Posts: 187

PostPosted: Wed Jul 31, 2013 9:41 am    Post subject: Reply with quote

Dear Sir,

1. I have attached a sample photograph. I was not saying that this is looking ugly.
Is this looking good or not, is subjective.

2. Plastic modulus can be calculated for any section, no doubt. But I think the original question was, whether the section will behave plastically before ultimate failure? ; the Section is plastic or not?. I guess the sections is slender and shall be designed using elastic theory. (I am yet to refer some books / codes).

Regards
Tamilarasan



New Bitmap Image (2).jpg
 Description:
 Filesize:  258.37 KB
 Viewed:  1408 Time(s)

New Bitmap Image (2).jpg


Back to top
View user's profile Send private message
Display posts from previous:   
Post new topicReply to topic Thank Post    www.sefindia.org Forum Index -> SEFI General Discussion All times are GMT
Goto page 1, 2  Next
Page 1 of 2

 

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum


© 2003, 2008 SEFINDIA, Indian Domain Registration
Publishing or acceptance of an advertisement is neither a guarantee nor endorsement of the advertiser's product or service. advertisement policy