Free field deformations during seismic loading

[Okiryu]

Hi ! for seismic loading, it is known that there are two type of loadings that affects the structure: inertial and kinematic loadings. Inertial loadings are inherent to the response of the structure. Kinematic loading is based on free field deformations (soil deformation due to the earthquake loading). This kinematic loading add an additional loading to the foundation, which is more critical for pile foundations (add additional loading in the pile which produces more bending and consequent moments). My question is: how do you know if the soil will deform and create kinematic loading in pile foundations? Is any rule of thumb in order to consider kinematic loading in the pile analysis? Also, if kinematic loading is considered, how do you quantify it? or do you need any other considerations?

 

[Okiryu]

Perhaps I need to look at some wave mechanics theory?

 

[Mccoy]

Hi Okyriu, this is a good article, bsed on eurocode 8, which might satisfy at least in part your questions

SOIL-PILE KINEMATIC INTERACTION:
NEW PERSPECTIVES FOR EC8 IMPROVEMENT

http://www.mccoy.it

 

[Retrograde]

Poulos has done a lot of work in this area.

"Practical approaches to seismic design of deep foundations" (2015), Proc. 19th NZGS Geotechnical Symposium

 

[Okiryu]

Thanks for the good references !

I understand that this is a complex analysis which involves intense analysis. However, I used this simplified approach: I used DEEPSOIL software (which is similar to SHAKE) and calculated the strains/displacements for my soil profile and my specific earthquake. Then, if I need the forces due to the kinematic loading, I can multiply these displacements by the soil springs (lateral coefficient of subgrade reaction). Something similar to is indicated in Poulos paper that Retrograde suggested.