Kassem Dib's Activities

Dynamic with consolidation analysis in 2013 versions

Kassem Dib — Tue, 20 Jun 2023 22:16:27 GMT

Hello..

Does plaxis 2013 contains the dynamic with consolidation analysis type ?

High pore pressure using UBC sand in earthquake and dynamic wind loads

Kassem Dib — Tue, 21 Feb 2023 13:37:27 GMT

Hello..I Know that plaxis has UBCSand PLM model to model the liquefation, my question is : is it necessary to use multiphase material element ? (Not solid element). Why I am asking that beacause UBC Sand takes only undrained A option, then it does not consider undrainrd shear strength limit, so the pore pressure could be developped to very hight values especially in case of an earthquake (very fast cyclic loads) and dynamic wind load (load speed much smaller than seismic loads).

Therefore:

1)is it necessary to use stress-pore pressure element (by python subroutine) ? or

2) I should consider slow cyclic load (wind loads) as static loads during earthquake phase to prevent high increase of pore pressure?

Material Point Modeling USDM (MPM)

Kassem Dib — Fri, 31 Mar 2023 00:51:43 GMT

Hello..I am looking for material point modeling usdm (MPM) that used for large deformation problems could you provide it?

I need it for the simulation of pile driving process.

Tuned Mass Damper Modeling

Kassem Dib — Tue, 21 Mar 2023 17:44:25 GMT

Hello..

I am working on the effect of the tuned mass damper on the response of an offshore wind turbine. I need to define a dashpot at the top of the tower.

Is there any way to define it ?

Regards

USDM of UBC Sand

Kassem Dib — Wed, 25 Jan 2023 22:01:10 GMT

Hello..I am working on liquefaction analysis for an Offshore wind turbine.. I am using Plaxis 3d 2013 , unfortunatley..the UBC sand does not exist as built in model.. could any one help me sanding the USDM of this model?

Plaxis 3D. rotational displacement of embedded beam elements?

Yang Yang — Tue, 21 Feb 2023 21:04:44 GMT

Plaxis 3D. Is it possible to visualize and export the rotational displacement of embedded beam elements? It appears that only translational displacements (ux,uy,uz) can be visualized and exported.

Connection assumption

Arash Nikvar Hassani — Tue, 21 Feb 2023 16:39:08 GMT

The question is how Plaxis considers the connection between embedded beam row and plate element like slab?

I have a sheet pile and embedded beam row vertically in the ground and on top of the is the slab. I can use the connection tool to define the connection between sheet pile and slab since both of them are defined as plate element. but I can't do the same for slab and embedded beam row.

Monopile Stability Analysis during Installation

Rein Voogd — Mon, 13 Feb 2023 10:29:53 GMT

Dear all,

I am in the process of doing an analysis of the stability during installation of an offshore monopile in PLAXIS 3D. For this analysis, I am using the HSsmall model for the sand layers.
For this analysis, I have the following setup:

- A monopile of a total length of 70 meters embedded 10 meters into the ground.

- Watertable at the bottom of the model (- 50 m) to perform an effective stress analysis using the submerged weight of the soil

- A rigid body at 35 meters above ground level in the center of the pile to perform a translation in x-direction (Displacement condition)

The analysis has the following phases:

1) Insert the pile using a "Wish in place" method

2) Push the pile at the rigid body position to 1 meters in x-direction

3) Pull the pile at the rigid body position to -1 meters in x-direction

4) Push the pile back to the original centre position

Below you can see an image of the set-up

After performing the calculation, a horizontal force-displacement plot is made. The result indicates a "hardening" response of the soil when pushing the pile back to the centre position during phase 4 (More force required to push the pile back during phase 4 than phase 2). This is shown in the figure below. To me, this seems unrealistic. I would expect that the soil becomes disturbed and pushing the pile back would require less or the same amount of force.

To further analyse the soil response, I inserted an extra phase of "push-pull-push" to the pile. Unfortunately, the model fails at the start of the second cycle of loading.

My question is, how can I avoid this hardening response of the soil and get a more realistic response? Is this perhaps a limitation of the HSsmall model?

Kind regards

Shallow foundation - Soil springs

Mohamad Raad — Mon, 20 Feb 2023 15:24:53 GMT

Hello, how can we neglect the soil springs between the shallow foundation and the soil beneath it in case where the foundation is sitting on piles and the design requires that all loads are transferred exclusively to the piles? If it's by defining a dummy soil the plate's interface element, what properties should it have? Can it be done by making the plate element few millimeters above the soil, hence they become contactless?

Thank you for your valued help.

Slow Analysis time

Kassem Dib — Mon, 17 Oct 2022 12:25:56 GMT

Dear Engineers..

I am simulating the response of an onshore wind turbine to seismic loads..

for soil I am using hypo-plastic model.

the calculations phases are : the initial phase, the self weight, a dynamic pre-Earthquake phase (100s) , the earthquake phase (20s) , the post earthquake phase (80s)

for the Pre-earthquake phase: the time step is chosen as 0.01s (max stored steps is 1000, and maximum steps is 1000, the number of sub steps is 10, and the tolerated error is 0.01 by default)

for the earthquake phase : the time step is 0.001s (max stored steps is 2000, and maximum steps is 2000, the number of sub steps is 10, and the tolerated error is 0.01 by default)

the problem is in post-earthquake (after degradation of soil stiffness) : when choosing 0.01s time step (max stored steps is 800, and maximum steps is 800 the number of sub steps is 10, and the tolerated error is 0.01 by default) the number of inaccurate plastic point became 0, but the global error did not reach the maximum allowable value, iterations continue until they reach the max number of iterations (60) but the solver continue to the next substep althought the global error did'nt reach the maximum allowable value.

I am worried about the accuracy of the analysis.

the attached image clarify my problem

Plastic interface points. I am getting a large number of inaccuracies when calculating.

Jack Davies — Mon, 01 Aug 2022 10:38:43 GMT

This seems to be when I add water in one of the phases of staged construction. Any idea why these are so inaccurate?

About service request

Kassem Dib — Mon, 17 Oct 2022 14:37:53 GMT

Dear Stefanos Sotiropoulos

Could you help me please how to request a service from the technical team as you suggested to me earlier ?

I got this message when I tried to request a service

Create Custome connection in plaxis 3d V20

Kassem Dib — Wed, 05 Oct 2022 09:10:12 GMT

Hello..

I am trying to model an offshore wind turbine for my PhD thesis (WholeModel.jpg and SideView.jpg), tower is modeled as plates and the blades are modeled using beam elements. Now i need to create hinge connection to allow blades rotates around rotor point (see Zoom.jpg).

I tried to do like the video published by Bentley (https://communities.bentley.com/products/geotech-analysis/w/wiki/45878/custom-connections)

But the following error massage still appearing before run the model.

Micha van der Sloot

Stefanos Sotiropoulos

Could You Help me please..

Ask A Question I

Wed, 05 Oct 2022 08:10:45 GMT

Ask a question in a forum.