×
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

Design of Building for both wind and sesimic

Design of Building for both wind and sesimic

Design of Building for both wind and sesimic

(OP)
I recieved a project a couple days ago to do.  It's s one story wood structure about 100'x50'.  It's not rectangular, but skewed about 30 degrees maybe a bit more.  Anyways, I have do design for the governing load out of wind and seismic.  It's in Michigan so I think wind will govern.  There are 18' wide common trusses that bear on an exterior bearing wall and interior beams (supported by intermediate columns)  The rest of the roof (at the interior portion of the building) is made of flat roof trusses.  I've been reading IBC 2003 and 2006 and am confused about the process of how design for seismic.  There are so many figures I don't know which one to use, the 1 second or .2 second figures.  Overall, I'm just not sure of the procedure to find the g value to multiply by the self weight of the structure.  I calculated the wind load (MWFRS) to be 20 psf, so I'm assuming this will govern but I still need to do the check.
THanks

RE: Design of Building for both wind and sesimic

Do you have a supervisor to guide you through this process?  The 1 second and short term spectral response accelerations to which you refer are a starting point.  You don't multiply those by the building weight to yield a seismic force.  Get each of those accelerations for the location of your building, and go through the equations in the code to arrive at the story shear to determine if wind or seismic governs.  The controlling forces of wind or seismic need to be verified for each building component.  With the structure you describe, it appears there are also irregularites to consider, and you should walk through the process with your supervisor.

RE: Design of Building for both wind and sesimic

I seriously doubt seismic will control for a one story wood structure, even if you are in lower Michigan.  Rather than waste time calculating seismic forces, see if you automatically qualify for Category A.

DaveAtkins

RE: Design of Building for both wind and sesimic

(OP)
Should I take the worst case of the short term and one second response spectra g values?  I'm going to really get into reading it today, I would like to be knowledgeable before I begin working on it at work.

RE: Design of Building for both wind and sesimic

faromic,

Based on these questions of yours, I would second what JKStruct says and get someone who knows how to do seismic design to help you on this.  

There is really no such thing as wind, or seismic, "governing a building".  Each case (wind or seismic) should be included in the various load combinations listed in chapter 16 of the IBC and each element of the building should be checked for all those combinations.  It may very well be (and usually is) the case where a combination with wind will govern one design element (say a brace, stud or connection) and seismic control other elements.

DaveAtkins may have a helpful point though - if it is an SDC A then the seismic loads throughout may be low enough where wind cases would control most designs.  But not understanding the basics of seismic design would tell me you need to at least get some good direction on this.



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