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AISC -2010 , MBMA-2012 provision/clause

 
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vrpatil
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PostPosted: Thu Feb 25, 2016 8:58 am    Post subject: AISC -2010 , MBMA-2012 provision/clause Reply with quote

Dear All,


As one of PEB manufacture considered DL+ 0.6WL instead ofDL+WL as there is provision/clause in latest code AISC-10 or MBMA-2012. But I amnot seen like that in old code.  As permy view DL+WL is one of governing load combination & how we cannot avoid. Pleaseprovide guidelines/views on this with respect to new revision etc. <o></o>

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vrpatil
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N. Prabhakar
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PostPosted: Thu Feb 25, 2016 12:55 pm    Post subject: Reply with quote

Dear Er. Patil,

If the PEB structure is being put up in India, please follow Indian Codes IS 800 : 2007 and latest IS 801 only, and not any other foreign codes as these are invalid legally.  Apart from this, how anyone can consider a lower 0.6WL instead of WL?  This has no logic.

With best wishes,

N. Prabhakar
Chartered Structural Engineer
Vasai (E)
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vrpatil
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PostPosted: Thu Mar 03, 2016 7:54 am    Post subject: AISC -210 , MBMA-2012 provision/clause Reply with quote

Dear All,<o></o>
Further more, I have studied old AISC codes along with new revisions. I found one change from IBC 2009 / ASCE 7 05 is that wind speeds in IBC 2012 / ASCE 7 10 are now ultimate values and associated with risk category and have increased about 30%.  That increase is may be counter balanced by new load combinations that reduce the wind load factor within the ASCE 7 USD/ASD combinations from 1.0 to 0.6 (as well in LRFD 1.6 to 1.0) depending on the combination.<o></o>

But PEB manufacturer are considering basic wind speed as per IS code IS 875 part 3 1987 Basic wind speed such as 39 m/s only & reducing load factor from 1 to 0.6. Hence the reducing wind pressure /load by 40% which is not proper.  <o></o>

It is required to take care dealing with PEB supplier as far as AISC revised code concerned.<o></o>

Please provide views on this.<o></o>

Prabhakar Sir thank you for replay & guidance.<o></o>

Regards,<o></o>
vrpatil
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Abishek_Siingh
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PostPosted: Thu Mar 03, 2016 9:50 am    Post subject: Reply with quote

Dear Prabhakar Sir,

Your point is very true, but it will fall on deaf ears. I will tell you why.

PEB manufacturers (I know many of them properly), are scared of the IS800 series codes because they give very high quantity of steel. Compared to that AISC/ MBMA codes give about 25% reduction in PEB steel quantity. This can be a major difference between them getting the project or not.

Also, all (yes ALL) PEB industrial sheds designed in India are as per foreign codes,with the connivance of all Contractors who execute it at site. I tried to raise a voice against this at office but then my voice nearly became the difference between me retaining my job or losing it.

Best,
Abhishek
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N. Prabhakar
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PostPosted: Fri Mar 04, 2016 5:33 am    Post subject: Reply with quote

Dear Er. Patil and Er. Abhishek Singh,

Er. Patil has rightly pointed out the anomaly in mixing clauses of two different codes for the calculation of design wind loads.  If they follow only one code throughout, the discrepancies in design wouldn't be much.  This practice of mixing clauses of two different codes in the of design of structural elements with thin flanges and webs for bending, axial force and shear has been very much there, to suit one's convenience, by structural designers of PEB structures.   It has been pointed out earlier also by several Sefians in this discussion forum. Unfortunately, many structural engineers in India are RC Design based and not fully conversant with various aspects of steel design.  As such, many steel designs that are submitted for approval are gladly accepted without any comment.  

With best wishes,

N. Prabhakar
Chartered Structural Engineer
Vasai (E)
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logeshcivil
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Joined: 07 Aug 2017
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Location: Coimbatore

PostPosted: Thu Aug 09, 2018 6:47 am    Post subject: MBMA Reply with quote

Can anyone provide me with link for MBMA 06?

Thank You

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Logesh
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