×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Wind Loading of Silos

Wind Loading of Silos

Wind Loading of Silos

(OP)
Hi all,

I have a question regarding AS1170.2 Appendix E.

We have been asked to provide an incremental base wind pressure  for a rectangular steel silo supported on a steel frame. The overall height is 25m and in plan 11 x 4 m.

Can I utilise the aspect ratio correction factor (Kar) in T.E1 to reduce my base pressure? In this case possibly by upto 30%.

Undergrad@work.

 
 

RE: Wind Loading of Silos

Someone please correct me if im wrong, but I was under the impression that Appendix E of AS1170.2 only applies to individual members in frames etc whos aspect ratio is greater than 8, which in this case will not apply to the silo. You can obviously utilise it for the steel frame members though.  

RE: Wind Loading of Silos

and before someone else posts it, I will add that as an undergrad you should be going through the problem with an experienced engineer

RE: Wind Loading of Silos

I agree with handex. I would use
Section 5.4 EXTERNAL PRESSURES FOR ENCLOSED RECTANGULAR BUILDINGS.

This should give pressure coeff someting like +0.8 on the windward face and -0.5 on th eleeward face.

RE: Wind Loading of Silos

(OP)
Handex

Thanks for your input and you are right, it is used for individual exposed steel members whose aspect ratio is greater than 8 and I should be going through it with an experienced engineer.

It was an experienced engineer who adopted this method of analysis using the code and I have been asked to work out the base pressures. I have discussed it with other engineers here and have also been told to consider it as an enclosed rectangular building. I believe a silo undergoes vastly different loading to an enclosed building and therefore that part of the code might not be as applicable as it first seems. The structure is also in a cyclonic region.

Using Appendix E gives me results that are nearly twice as large as using the section for enclosed rectangular buildings. If I utilise the Kar factor I am somewhere in between.

I guess i wanted to get an idea of how best to apply the code to a situation that isnt explicitly covered within it and see if I can get a few opinions of experienced engineers along the way.




 

RE: Wind Loading of Silos

A silo of a different shape than rectangular would see different loading, but a rectangular silo is just an enclosed building.  Not sure why you think otherwise.  Use Section 5.4 as sdz and some of your experienced engineers suggest.  The fellow who is using Appendix E is off base.

RE: Wind Loading of Silos

As suggested, I would also use a drag coeff. or form factor of
+0.8 windward and -0.5 leeward for the silo.
However, I believe there is a difference between an enclosed bldg.
and this silo supported on an open frame structure.
On an enclosed bldg one would evaluate the leeward press. using
an exposure coeff. Kh evauluated at the eve height.
Where on this setup with the silo, one would use Kz evaluated
at different heights both for the windward and leeward.
The reason for this, on the silo setup, is that wind press. can escape thru the open support stl at the base of the silo and
influence the press. on the leeward side.  

RE: Wind Loading of Silos

(OP)
Thanks everyone for your responses.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources