Asking for Tips in Designing Manufacture Building against Wind Load

[1rv4n]

Hi all, I beg anyone who could help me sharing some tips in designing a manufacture building especially in resisting wind load. This is my first time designing a very widely wind exposed building.

Currently I am working on a steel pipe rolling mill building project and I found difficulty with wind load. The distance between coloumns (which is 8 meters) cause the load caused by wind very large and I also found difficulty in choosing effective steel profile for bracing since my usual choice bracing (angle or double angle) are too slender for length like this.

And the building shape (which is L shape building) gives me extra headache.

So I really beg anyone who has experiences sharing your tips for me in solving wind problem on L shape widely wind exposed building. Thank you for any helps.

 

[hokie66]

This is too broad a subject for us to give you meaningful advice. You should not be placed in the position of designing the structure for a rolling mill building without appropriate mentoring/guidance.

 

[hemal1214]

The design for wind loads depends on height of the structure. I am not sure how is your approach to design it but some basic information is:

1) Find the wind pressure on the building using appropriate codes.
2) Select a Main Wind Force Resisting Frames (MWFRS)to resist the wind load i.e. moment frames or X - braced frames.
3) Distribute the wind load on the MWFRS based on wind pressure and tributary area of pressure. Design the moment frame or braced frame to resist the load. You can certainly use W sections for bracing design.

Hope this basic idea helps..

 

[MiketheEngineer]

As noted - please get some help for a project of this size.

 

[1rv4n]

@hokie66 & Mike : I totally agree with you. But, the fact that I don't get decent mentoring can't be changed. Truthfully, we are less experiences in this kind of project since we usually works on Jetty , Dolphin, and other marine structure. That's why I don't get decent mentoring from my seniors and supervisors. So hopefully I could get some advice from you.

@hemal : The W section you mention means Wide Flange Section? Can I really use WF section as bracing in this kind of structure?

 

[JedClampett]

Well, let me be the hard guy as I'm in the mood. Its illegal and immoral to design structures that you're not capacble of. It says so in the State Engineering Acts (in the US) and Code of Ethics. No one is going to want to hear about a lack of mentoring if a disaster happens.
At a bare minimum, you or your boss needs to hire an experienced reviewer to check this design. That leaves the responsibility of sealing the design kind of unknown, but at least you'll have some oversight.
There's only so much you can pick up off a website.

 

[hokie66]

1rv4n,
Jed's comments are US based, but generally apply wherever you are. Your situation is perilous, but we can't help much. If your company is not experienced in designing braced steel buildings, you will have to retain the services of a structural engineer who knows how. But just one answer...yes, lots of different shapes are used for bracing, including wide flanges, but closed shapes like circular hollow sections and square hollow sections are generally more efficient for compression braces.

 

[csd72]

There are lots of very good guidance books on this type of structure published by the aisc or similar. If your company insists on going ahead with the design of a building that is so far from the realms of their experience then at the very least they should invest in a few of these books.

Industrial buildings are not that complicated but they do have a few things that can catch the unwary.

 

[1rv4n]

All, I need some correction, please correct me if I'm wrong.

In designing wind load on structure, I have Wind Factor (according to my Country's Code) +0.9 for inward surface, -0.4 for outward surface, and -0.4 for parallel surface. Now here comes the problem.
The wind factor for the parallel (-0.4) means it is suction load, so should I assign the load parallel to the wind direction & wall surface or perpendicular to the wall surface?

Currently I'm assigning the load parallel to the wind direction and suddenly I remember that in assigning wind load, there is only two condition which is press and suction only (which both are perpendicular to the surface). If so, then even if the surface is parallel to the wind direction, the load is still applied perpendicular to the surface, not parallel. It explains why I have big problem with my wind...

In conclusion, there is no parallel wind load, only press and suction load. Please correct me if I'm wrong....

 

[csd72]

If the pressure has no surface to act on, is it still a pressure? [fumanchu]

Forces exerted by wind along a surface are called drag forces as opposed to pressures which act perpendicular to a surface.

Make sure that you add the internal pressure and you should allow for the worst case opening being open for each wall when you are calculating internal pressure (doing cladding loads).

 

[patswfc]

Your -0.4 will be a suction force on the side walls. So you are correct in thinking that the wind should be applied perpendicular to the wall.

However you can still get some wind parallel to the side walls
which is caused by frictional drag. I dont know if this appears in the code that you are using. It is usually not very significant, e.g. in the UK code the drag coefficient varies from 0.01 for smooth surfaces to 0.04 for ribbed surfaces.

 

[1rv4n]

Ah, it really explain why I messed up with the wind since I apply the wind load factor as drag factor (which is said by mr. patswfc to be small).

Btw, I kinda confused since the building is L shaped, then there should be turbulence in the inside corner of this L shaped building. Can someone share some knowledge how the wind will effect the building on its inside corner?

My senior told me that since the building is not tall enough (16 m only), I should ignore the turbulence. But, I don't think that is wise enough. So please teach me...

 

[csd72]

Turbulence is not normally an issue for low rise buildings like this.

 

[oldrunner]

Hey guys, you might ask him if he has a steel handbook. It's surprising how many firms doing what he's doing don't have a handbook or manual. Hope his building doesn't blow apart because it doesn't appear that there is any competent oversight.

Kinda of a bad day a Black Rock. Just went through this with a firm that had a guy from someplace with some kind of a degree providing a design and I could never figure out why the welds were called out in plain English and the material sizes were descriptions instead of standard callouts. Who complained that the shop knows what he means so not all of the welds have to be called out - even though the whole design someday somehow will be reviewed by one of our federal agencies and will probably pass.

Sorry; at least this fellow is asking for help and not building something that we'll have to pull down down and redo. Just read the Editorial in the May edition of Structure magazine. That will make your day.

 

[ToadJones]

Well, there could be a giant elephant in the room that has been missed here....
I know that the topic is wind loads, but I have never seen a rolling mill that didnt have large EOT cranes in it.
Determining your wind loads and designing for them is, IMO, much easier than designing a mill building for crane loads and crane loads in conjunction with building loads.
These types of questions scare me!!!

 

[ToadJones]

csd72-
there are parts of industrial buildings that, in my opinion, can be very complicated. Often the loads are not code prescribed. The work on the front end of the design can be tremendous.
I know what you are saying though and don't mean to offend you at all...just thoughts.

 

[csd72]

Toadjones,

Yes I understand where you are coming from. You definately need a really good understanding of the wind code in order to design them properly. Other items such as crane beams can be just as tricky.

Though compared to many other types of structures, 90% of it is pretty straight forward.

 

[boo1]

try

http://timber.ce.wsu.edu/Supplements/WindDesign/intro.html

 

[1rv4n]

@ToadJones
It's true that the crane load design is supposed to be more complicated than designing the wind load, but in the process, I have a very good guide book (which is CISC - Crane Supporting Steel Structure) which help me a lot not to mess with the crane load. I agree that the crane load is very complicated, but I managed to handle it well according to the code.

Meanwhile, I have no guide for wind load. Wind load is supposed to be so easy to be understood even without guide (at least, that is what I thought) and unfortunately, I don't understand them. So I found harder time with wind load instead of crane load.

And moreover, my hard time with wind load is more because I misinterpreted my theory instead of not understanding at all. But through everyone's help, I managed to correct my misunderstanding and design it correctly.

@Boo1
Thank you for the link. Really good I think.

@All
Thank you for your kind help that I manage to handle my lack of knowing in wind design. Hopefully I didn't bother you all with my stupid question.

 

[bgatto]

Seems quite too late for you, but maybe this will help somebody else:

http://www.steelbiz.org/Discovery/AllResults.aspx?q="wind"