Embedded element or plate element to model a pile?

Question

Hello, 
 I use Plaxis 2D. When modeling piles in a piled raft, does modeling as plate elements give better behavior than modeling them as embedded beams, or not ? - How can EI EA and w values ​​can calculate for a pile defined as plate element? Thank you,

Vasileios Basas · Answer

Hi Batuhan, 
 When modelling a row of piles, as is the case in a piled raft foundation, it is preferable to use embedded beam row elements instead of plate elements (see Appendix C of the PLAXIS 2D - Material Models manual). This is because an embedded beam captures the interaction with the soil more accurately, as the material parameters distinguish between the parameters of the pile and the parameters of the skin resistance and foot resistance. 
 Regarding your second question, I would say that plates are considered planar (surface) elements and extend to infinity under the plane strain assumption. So, in theory, you could divide the stiffness and weight parameters by the out-of-plane spacing. However, the behaviour would not be entirely accurate, considering that you assume the element's average ("smeared") behaviour. As pile (group) behaviour is a three-dimensional problem, I suggest you use PLAXIS 3D instead if that is an option.