×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Are you an
Engineering professional?
Join Eng-Tips Forums!
• Talk With Other Members
• Be Notified Of Responses
• Keyword Search
Favorite Forums
• Automated Signatures
• Best Of All, It's Free!

*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.

# Site response for dummies for liquefaction analysis

## Site response for dummies for liquefaction analysis

(OP)
i was just wondering what the difference is between the following analysis methods used to calculate the CSR for a liquefaction analysis in a site response analysis:

1. linear total stress (SHAKE?)
2. non-linear total stress
3. non-linear effective stress

what does the "linear" thing mean? does that mean that when the soil is shaken it behaves elastically (i.e. just deforms a little bit) and non-linear means that when it is shaken, it deforms a lot i.e. elastic ("linear") to begin with and then plastic after that (non-linear).

Also, what does the total stress and effective stress thing mean in this context?

### RE: Site response for dummies for liquefaction analysis

Doughole

Linear elastic methods: as you say, it implies a liear elastic response, when the stiffness degradation of the soil layers crossed by seismic waves is not significant. This happens typically in rigid soils and with low-intensity earthquakes. LE methods are also used to compare the theoretical response model to empirical H/V measurements

Equivalent linear: the degradation of soil layers is significant and this goes together with the increase in damping ratio. It is a must in strong earthquakes and weak soils. It implies a stepwise iterative linear elastic response which mimics the nonlinear response in reality.

Non linear: it is a must in liquifiable soils,in very weak soils where plastic effects are expected, in soils where fluid pressure effects are not negligible; also can be more accurate in thick deposits of not very rigid layers, avoiding effects such as overdamping of high frequencies. Cons are model uncertainties and more complex analysis and interpretation.

Total stress: no pore fluids effects are considered
Effective stress: pore fluid effects versus time are considered

#### 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.

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:

• Talk To Other Members
• Notification Of Responses To Questions
• Favorite Forums One Click Access
• Keyword Search Of All Posts, And More...

Register now while it's still free!