Obtaining the response of bending moment and shear force for the monopile if it the pile is modeled as volume element not as a embedded beam?

Question

I have modeled my monopile foundation for offshore wind turbine. The pile is modeled as volume pile using plate element and it is subjected to the horizontal load at the top. I want to get corresponding response of bending moment and shear force which can easily be obtained in embedded beam. But I am getting difficulty to obtain it for the volume pile. It will be very helpful if Plaxis team can help me in overcoming this issue.

Hung Ho Manh · Answer

Hello Rituraj, 
 It is a bit confusing as you mentioned modelling a volume pile, which is often understood as a solid pile &ndash; soil element, by a plate element. But I guess you modelled it as a pipe pile for the monopile. If so, there is no straightforward way to extract forces of the pile from the plates but you may consider using a trick called a hybrid pile, which is shown in the paper: https://www.sciencedirect.com/science/article/pii/S0038080620310593 . Since it is presented by the authors, you may check and try it carefully before using it for your case.

Hung Ho Manh · Answer

Hello Rituraj, 
 Thanks for clarifying. We have seen that some studies also used that method for pipe piles with closed-end tip. Well, with your hollow pile, it seems not to be suitable here since the interaction between pile (inner and tip) and soil are different from that case. That is why I mentioned it should be checked and tested before use. 
 For a hollow pile, you may use two beams with low stiffness on the pile at opposite sides (front and rear) of the pile. This is to extract strains on the beams, which is similar to what we achieve when we attach pairs of strain gauges on the pile in a pile test to get bending moment later on. The diameter of the beam should the same as pile thickness. For more details, you may also refer to the literature on how to calculate bending moment from strain gauges in a pile test (or Mechanics of Materials knowledge). Our colleague also mentioned this tip here: https://communities.bentley.com/products/geotech-analysis/f/plaxis-soilvision-forum/225111/plaxis-3d---how-to-model-monopile-for-obtaining-load-displacement-curves-under-lateral-loads

Obtaining the response of bending moment and shear force for the monopile if it the pile is modeled as volume element not as a embedded beam?

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