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PEB design
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sahildhingra
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PostPosted: Thu May 10, 2012 12:35 pm    Post subject: PEB design Reply with quote

Could anyone tell me why peb is designed in 2d? Why not in 3d?
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sahildhingra
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PostPosted: Thu May 10, 2012 12:38 pm    Post subject: Reply with quote

Can anyone please send me the spreadsheet for purlin design, connection plate,anchor bolt and base plate?
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VPandya
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PostPosted: Thu May 10, 2012 5:15 pm    Post subject: USE MBMA Design Manual based on code IBC 2006/2010. Reply with quote

Dear Mr. Sahildhingra
1) Use revised Metal Building Manufacturers Association (MBMA) Design Manual based on IBC 2006/2010. You can also use software  MBS  for design of PEB Structures.

These two are  widely used in USA for all PEB Steel Buildings.  

2) 2D Vs 3D Analysis and Design of  PEB Steel Frames.
    Say there is a 108m Long and 20m wide and 12m high PEB, Ware House .  Let us  say PEB frames are span at 6m. Now you have 17 middle  PE frames + 2 PE End frames . Total 0f 19 PEB Frames  at 6m span.
All these 19 frames are repeatative structure of size 20mX12m. So you make one 2D Model of  20mX12m and do Analysis and Design. You design one or two 2D frame and you design all 19 frame or the whole structure.


There is no 3D effects in such structures. If you use STAAD/PRO Axis system where XZ is Plan and XY Elevation in Long Direction 108 m and YZ  Elevation in width direction 20m,  then Structure is repeatative in YZ direction. So a  2D Analysis and Design of Frame in YZ direction, designs the whole structure.  

Regards.

Vasudeo Pandya  P.E. : S.E.
Structural Engineer


Last edited by VPandya on Fri Sep 29, 2017 5:24 am; edited 1 time in total
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suresh_sharma
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PostPosted: Fri May 11, 2012 2:18 am    Post subject: Reply with quote

Mr. pandya,

You have given a good reply but please advise as to how to account for 3D effect of wind pressure in 2D structure. In any structure wind pressure acts on all the 4 walls at a time  either as suction or pressure(Cpe and Cpi). Please elaborate.

Secondly if PEB is used as frame structure for building, then EQ forces are requred to work on 3D model. 2D modelling may be good for small truss type structure with inclined roof. When no software was available, analysis used to be performed as 2D only.
Please also advise for my personal sake as to which is the widely used PEB software in India.
I am the beginner in steel structure.
Please highlight.
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VPandya
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PostPosted: Fri May 11, 2012 5:35 pm    Post subject: Fig 14.9 " Design Of Steel Structures by N . Subramania Reply with quote

Dear  Mr. Sharma,

To answer your question, How can we only do 2D Analysis and Design of full  PEB Rectangular Building of 20m Wide X 108m Long x 12m High, the size I picked up, for Wind Loads and Earthquake Loads?

ANSWER:  Go to Fig 14.9 Typical Portal Frame Construction of  " Design Of Steel Structures by Dr. N . Subramanian. Now we have to do Analysis and Design of this Structure.  There are two ways to do it.
OPTION 1)  A full 3D Model of all Frames, that is 3 middle Rigid Frames, 2 End Rigid Frames and  2 Braced Frames in Long Direction. Also with all purlins and Girts for siding.
OPTION 2) 3 Simple Plane Frame 2D analysis and Design.
     a)  One 2D Frame of Rigid Frame out of 3  Frames.  
     b) One 2D Frame of End Wall Rigid Frame out of two End Wall Frames.
     c) One 2D Frame of  Long Wall with Bracing out of two Long Walls.

Option 2) will give you same answers in Member Forces , Deflections and Member Sizes. There is no problem in applying WIND LOADS and  EQ. LOADS  in optiion 2).
Lateral Loads, Wind or Earthquake will go Bracings  in two directions through Roof Diaphragm (Horizontal Bracings). Check the Lateral Load Path.  What you are doing in Option 2) is recognizing the Symmetry and Regular Shape of your Building.

Option 1) in an Over Kill  of Structuiral Analysis and Design. I have seen a Structural Engineer in USA  using Option 1) , and Size of his STAAD/PRO Model with 4000 members or so was a waste of time. He could have done entire building with 3,  2D frames with total; of  40 or 50 members and  not  4000 members.
     
Remember we engineers need to recognize the  Regular Shape and Symmetry of our Structures. Some one can ask us why you need  say a 4000 member STAAD/PRO model for this Regular Shape, Symmetrical Building? You could have done this with total of 40 or 50 members model with few 2D Frames.

Some 3D Structures which have Irregularites are shown in Dr. N. Subramanian book
in Fig. 3.21, 3.22 , 3.23 and 3.24.  These Structures have significant 3D effects and
you need a 3D model.     


Regards.

Vasudeo Pandya  P.E. ; S.E.  
Structural Engineer
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Dr. N. Subramanian
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PostPosted: Fri May 25, 2012 3:23 pm    Post subject: Re: Fig 14.9 " Design Of Steel Structures by N . Subram Reply with quote

Dear All,

Someone sent me a private email and raised some questions about PEB. I am giving them below for the benefit of those who are new to PEB.

1. Why PEB structures are to be considered, if so how to do the design, any reference books.
Pre-Engineered (PEB)buildings are ready made buildings in the sense, you see the suppliers catalog and depending on your requirements, order them so that they will come and erect it. By this way, it is quick and also since the components are made in the factory they are efficient. A number of companies exist in USA and also in India, who will supply you the catalog. For example, Butler Manufacturing company: http://www.butlermfg.com/gallery/. See also: http://en.wikipedia.org/wiki/Pre-engineered_building

The best book on this is by Newman, A., Metal Building Systems: Design and Specifications, McGraw Hill, 1997, 389pp.

2. I am planning to compare routine truss building with PEB building for the project work
Design wise both are same, it is like the difference of routine concrete buildings and prefabricated buildings.

3. Can we design PEB structures manually.
Sure! It is like any other truss or portal frame design

Best wishes
NS
VPandya wrote:
Dear  Mr. Sharma,

To answer your question, How can we only do 2D Analysis and Design of full  PEB Rectangular Building of 20m Wide X 108m Long x 12m High, the size I picked up, for Wind Loads and Earthquake Loads?

ANSWER:  Go to Fig 14.9 Typical Portal Frame Construction of  " Design Of Steel Structures by Dr. N . Subramanian. Now we have to do Analysis and Design of this Structure.  There are two ways to do it.
OPTION 1)  A full 3D Model of all Frames, that is 3 middle Rigid Frames, 2 End Rigid Frames and  2 Braced Frames in Long Direction. Also with all purlins and Girts for siding.
OPTION 2) 3 Simple Plane Frame 2D analysis and Design.
     a)  One 2D Frame of Rigid Frame out of 3  Frames.  
     b) One 2D Frame of End Wall Rigid Frame out of two End Wall Frames.
     c) One 2D Frame of  Long Wall with Bracing out of two Long Walls.

Option 2) will give you same answers in Member Forces , Deflections and Member Sizes. There is no problem in applying WIND LOADS and  EQ. LOADS  in optiion 2).
Lateral Loads, Wind or Earthquake will go Bracings  in two directions through Roof Diaphragm (Horizontal Bracings). Check the Lateral Load Path.  What you are doing in Option 2) is recognizing the Symmetry and Regular Shape of your Building.

Option 1) in an Over Kill  of Structuiral Analysis and Design. I have seen a Structural Engineer in USA  using Option 1) , and Size of his STAAD/PRO Model with 4000 members or so was a waste of time. He could have done entire building with 3,  2D frames with total; of  40 or 50 members and  not  4000 members.
     
Remember we engineers need to recognize the  Regular Shape and Symmetry of our Structures. Some one can ask us why you need  say a 4000 member STAAD/PRO model for this Regular Shape, Symmetrical Building? You could have done this with total of 40 or 50 members model with few 2D Frames.

Some 3D Structures which have Irregularites are shown in Dr. N. Subramanian book
in Fig. 3.21, 3.22 , 3.23 and 3.24.  These Structures have significant 3D effects and
you need a 3D model.     


Regards.

Vasudeo Pandya  P.E. ; S.E.  
Structural Engineer
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sandeep_chauhan
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PostPosted: Fri May 25, 2012 3:40 pm    Post subject: Reply with quote

Dear Sefians,
Some leading PEB manufacturers in the world with there web addresses are there in the link below.

http://www.mbsweb.com/htmls/clients%202.htm

Hope it will help.

Thanks
Sandeep Chauhan
Sr-Engineer (PEB Design)
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venkatesh
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PostPosted: Sat May 26, 2012 4:40 am    Post subject: Reply with quote

There is a book from insdag (INSTITUTE FOR STEEL DEVELOPMENT & GROWTH) which had  full worked out example of PEB Truss. The code for the book INS/080 and cost of book is Rs 900/-

Thanks and regards
Venkateshwar Rao
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thirumalaichettiar
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PostPosted: Sat May 26, 2012 10:01 am    Post subject: Reply with quote

If you become a life member of INSDAG you get 2 free book every year and discount price if u need HB that is published recently.

T.RangaRajan.
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ashisheck
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PostPosted: Wed Feb 20, 2013 7:46 pm    Post subject: Reply with quote

Dear sir

i have a work of foundation design of  semi peb structure
where reaction is

Load & Load comb. Fx kN Fy kN FZ KN moment at bottom of column (col.ht.=5m)

DL+LL 36.8 15.52 184
DL+wlx(sc) -108.5 -41 -542.5
DL+wlx(Pr) -141.5 -67 -707.5
DL-wlx(Sc) -101.5 -39 -507.5
DL-wlx(Pr) -138.5 -45 -692.5
DL+wlz(Sc) -87.5 -37 -437.5
DL+wlz(Pr) -162.5 -67 -812.5
DL-wlz(Sc) 35.5 15 177.5
DL-wlz(Pr) 35.5 15 177.5

this is at +5m. from ground. and after peb structure is rested on 5m length of RCC column
so column and foundation has a vary high moment
just in dl+wlz(pr) is 812.5 so i will design foundation in such heavy moment case.........

Thanks in advance


sandeep_chauhan wrote:
Dear Sefians,
Some leading PEB manufacturers in the world with there web addresses are there in the link below.

http://www.mbsweb.com/htmls/clients%202.htm

Hope it will help.

Thanks
Sandeep Chauhan
Sr-Engineer (PEB Design)
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