## Gravity wall seismic design - inertial force?

## Gravity wall seismic design - inertial force?

(OP)

Hello!

When designing a concrete gravity wall against sliding, overturning and bearing capacity in a seismic design situation by using a pseudo-static analysis, do you take into account the inertial force of the wall, expressed as F

In every book I look, they explain the pressure the earth exerts on the wall, but they don't talk about the design of the wall after we defined the soil forces on the wall. For example, by using the Mononobe-Okabe method we take into account the inertial forces of the backfill, and that is all contained into the P

Also, my question refers to making the design on the basis of stresses. In the other design method, where the design is based on allowable deformations, the inertial force of the wall is taken into account because it's needed to define the allowable ground acceleration.

As far as I remember, during classes in my faculty we never took the inertial force of the wall, but I found sources which take it.

What are your experiences regarding the subject?

When designing a concrete gravity wall against sliding, overturning and bearing capacity in a seismic design situation by using a pseudo-static analysis, do you take into account the inertial force of the wall, expressed as F

_{i}=W*k (where F_{i}- inertial force, W - wall self weight, k - horizontal coefficient of seismic acceleration)?In every book I look, they explain the pressure the earth exerts on the wall, but they don't talk about the design of the wall after we defined the soil forces on the wall. For example, by using the Mononobe-Okabe method we take into account the inertial forces of the backfill, and that is all contained into the P

_{AE}force, but do we need to take the inertial force of the wall for the stability check?Also, my question refers to making the design on the basis of stresses. In the other design method, where the design is based on allowable deformations, the inertial force of the wall is taken into account because it's needed to define the allowable ground acceleration.

As far as I remember, during classes in my faculty we never took the inertial force of the wall, but I found sources which take it.

What are your experiences regarding the subject?

## RE: Gravity wall seismic design - inertial force?

"To investigate the wall stability considering the

combined effect of PAE and PIR and considering them not

to be concurrent, the following two cases should be

investigated:

• Combine 100 percent of the seismic earth pressure

PAE with 50 percent of the wall inertial force PIR and

• Combine 50 percent of PAE but no less than the

static active earth pressure force (i.e., F1 in

Figure 11.10.5.2-1), with 100 percent of the wall

inertial force PIR."

## RE: Gravity wall seismic design - inertial force?

Thank you, this is great information!

I wonder though, and I'd like to know, what recommendations do the other standards give and what procedures do engineers from other parts of the world use (I'm from Europe).

Eurocode 1998-5 only mentions that those inertial forces should be used, but doesn't specify how:

represented by a set of horizontal and vertical static forces equal to the product of the

gravity forces and a seismic coefficient.

## RE: Gravity wall seismic design - inertial force?

The reviewer didn't like our option and complained that we sould have used a consistent set of standards and concurrent inertial forces. We replied that the AASHTO recommendation was based on extensive studies by Al Atik and Sitar (2012), as is mentioned in the commentary to 11.6.5.1, and that EN1998-5, in point 7.3.1(1)P refers that "Any established method based on the procedures of structural and soil dynamics, and supported by experience and observations, is in principle acceptable for assessing the safety of an earth-retaining structure.". Our design was accepted at the time.

Hope it helps.

## RE: Gravity wall seismic design - inertial force?

Link

## RE: Gravity wall seismic design - inertial force?

For pile seismic design in Japan, the inertial and kinematic loading are treated separately since they do not occur at the same time. Japanese approach for inertial and kinematic loading may be in agreement with avscorreia's input about the AASHTO guidelines - both inertial and kinematic loadings do not act 100% at the same time...

See page 25 the PDF of this document from Boulanger et al.:

https://faculty.engineering.ucdavis.edu/boulanger/...