×
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

Impact of Seismic Site Classification

Impact of Seismic Site Classification

Impact of Seismic Site Classification

(OP)
Hi !... I do geotech so, sorry if this is a dumb question: what are the implications in the structural design if we change the class from D to E or F? Say, we have a mid size building (5 story) so the period may be about 0.5 seconds. My understanding is that for LOW periods, there is a trend for the spectral accelerations to become lower as the site class become worse.

RE: Impact of Seismic Site Classification

Not sure about the other codes, but for AASHTO it doesn't work that way. Going from D to E increases the design acceleration coefficents, resulting in higher design forces and displacements for structures of all periods. Site Class F requires site-specific analysis, which may result in lower forces, but can be quite costly.

RE: Impact of Seismic Site Classification

For the NBCC 2015:
Going from Site Class D to E is going from stiff soil to soft soil. Going from Site Class E to F is going from soft soil to "other soils" that require a site specific evaluation. You can view the trend of the F(T) values in Tables 4.1.8.4. Typically, for T>0.5 it appears the F(T) value will increase as Site Class goes from C to F.

There is also Note 103 in Commentary J where the "fundamental period of vibration" =< 0.5s for structures built in Site Class F, then the values for F(0.2) and F(0.5) can be determined assuming that liquefaction will not occur. This only applies for determining the site class and determining the site coefficients.

RE: Impact of Seismic Site Classification

(OP)
Thanks much for the responses. So, if T is less than 0.5 sec, then the site class and the site coefficients can be determine considering no liquefaction but the actual design of the structural elements should follow the code assuming that the site is class F?

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! Already a Member? Login


Resources

eBook - Manufacturing the Cars of Tomorrow
In this ebook, we'll explore how additive manufacturing is going to transform the way cars are made. This includes commentary from thought leaders such as Ford's CTO, Ken Washington, Customer case studies of ways 3D printing is being used today, and a variety of part examples where 3D printing is already impacting how automobiles are made. Download Now
White Paper - Smart Manufacturing for Semiconductor
New technologies and approaches present great opportunities for semiconductor manufacturers to achieve high levels of innovation, yield and improvement. This white paper explores some of these cutting-edge technologies and how they can be applied effectively in the semiconductor industry. Read about how Smart Manufacturing is transforming the semiconductor industry. Download Now
White Paper - Analysis and Simulation in Aircraft Structure Certification
Organizations using simulation and analysis tools effectively see the benefits in their ability to achieve certification faster and with drastically less total cost than those who do not maximize these tools. Read this White Paper to learn about how digital tools such as analysis and simulation help in aircraft structure certification. Download Now

Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close