The OpenSees Community

kamyarsa wrote: ↑Sun Nov 12, 2023 1:03 am Hello everyone, I am currently working on a project where I want to model a cantilever retaining wall, following Wiki's example. However, I am facing a problem where the wall element crosses the soil element during the excavation process in certain condition, such as when the wall is a 10-meter flexible wall. I believe this is happening due to the contact element not working properly. I use BeamContact2D element and Contactmaterial2D for the contact element and dispBeamColumn for the wall.

If anyone has any ideas or suggestions on how to fix this issue, I would greatly appreciate it. Thank you.

Sounds like you've got quite a task on your hands with modeling a cantilever retaining wall. It can be a bit of a head-scratcher when things don't go as planned, especially with something as complex as a 10-meter flexible wall . I see you're having a bit of trouble with the wall and soil elements playing nice during the excavation process.

Tackling this kind of issue can be a bit like solving a puzzle. Since you suspect the contact element might be the culprit, it's worth giving those settings a second look. Sometimes, it's the little details in the properties of your BeamContact2D element and Contactmaterial2D that can make a big difference. You know, things like stiffness, damping, or friction parameters can be quite finicky.

Also, considering the wall's flexibility, it's crucial to get that interaction with the soil just right. It's a bit like trying to balance a seesaw – you want everything to be in harmony.

It could also be helpful to play around with your model a bit more. Maybe tweaking the mesh or adjusting the boundary conditions might shed some light on the issue. And, don't forget about those simulation parameters. Sometimes, changing the time step or convergence criteria can be like finding the missing piece of a puzzle.

And hey, if all else fails, there's no harm in trying a different approach to modeling.

Keep at it, and I'm sure you'll crack it. Good luck with your project!

fefe wrote: ↑Thu Nov 23, 2023 2:26 am hy, everyone.
I'm start to use opensees 3.5.0. on tcl code (notepad++) and i have try some exemple codes. They work quiete nice but i have problems with all the DYSPLAYMODEL function.
In my PC with Windows 11 home i can't see the figure or img, and also if I try a simple command, nothing happen. Like:
#
set h 120
recorder display “Mode Shape 1” 10 10 500 500
prp $h $h 1
vup 0 1 0
vpn 0 0 1
viewWindow -200 200 -200 200
display -1 5 2
#
i need to do somenthing in particular or maybe i should use some extra software?

thank

I understand the frustration with the issues you're facing regarding the displayModel function. Let's see if we can troubleshoot this together.

First off, the displayModel or similar display functions in OpenSees are used to visualize the model or its response. However, these functions depend on certain graphical capabilities, which might not be directly supported in your environment. few things to consider:

Check OpenSees Version : Some builds of OpenSees, especially those intended for command-line use, might not include the graphical libraries needed for display functions.

Graphics Package Dependency: OpenSees uses external graphics packages for displaying models. For Tcl scripts, it typically relies on Tkinter (Tk), a standard GUI toolkit used by Tcl. Make sure that Tkinter is properly installed and configured on your system. Since you're using Windows 11, there could be compatibility issues or missing components that need to be addressed.

Correct Syntax and Commands: Ensure that your script uses the correct syntax for the display commands. Tcl is quite particular about syntax, and a small error can lead to functions not executing as expected.

In some cases, users integrate OpenSees with other software like MATLAB or Python for visualization purposes. This approach is complex but offers greater flexibility and power in visualization.

Graphics Drivers and System Compatibility: Sometimes, the issue might be with the graphics drivers on your PC or compatibility issues with Windows 11. Make sure your graphics drivers are up to date. Also, since OpenSees and Tcl/Tk have been around for a while, newer operating systems might introduce compatibility challenges.

Ensure Tcl/Tk is Installed: Tcl scripts with graphical output typically require Tcl/Tk to be installed on your system. If it's not installed, you would need to install it to see graphical outputs from your scripts.

cexuhan wrote: ↑Sat Aug 07, 2021 5:58 pm Hi All,

According to my knowledge, the uniform excitation can be achieved in Opensees by calling the "UniformExcitation" sentence. But if I wanna simulate the earthquake cases with non-uniform excitation, that is, considering that the ground motion excitation of the earthquake at different bearing positions is different, is there any feasible way to simulate it in Opensees?

Thanks a lot for any possible help.

Xu

Yes, you're absolutely right about the use of "UniformExcitation" in OpenSees for simulating uniform earthquake ground motions. When it comes to simulating non-uniform earthquake excitations, where the ground motion varies at different support locations, OpenSees does offer ways to handle this more complex scenario.

Non-uniform excitations in an earthquake simulation are important to consider, especially for large structures or those on irregular terrain, where different parts of the structure may experience different motions during an earthquake.

To simulate non-uniform excitation in OpenSees, you would typically use multiple "LoadPattern" elements, each with its own ground motion record. This approach allows you to assign different ground motion records to different supports or sections of your model, representing the varying effects of the earthquake at those points.

Here's a simplified breakdown of the steps:

Define Multiple Load Patterns: Create separate LoadPattern elements for each unique ground motion you want to simulate.

1. For each LoadPattern, apply a ground motion using commands like "PathTimeSeries" and "PathSeries" to define the time history of the ground motion. The ground motion data can be actual recorded data or generated data that fits your earthquake scenario.

2. You can then assign these load patterns to different nodes or elements of your structural model. This assignment is where you simulate the non-uniform aspect of the earthquake - different parts of your structure will be subjected to different ground motions.

3. Configure your analysis to consider all these load patterns. This setup might require a more complex analysis configuration, as you're dealing with multiple, potentially interacting, ground motions.

4. Perform the analysis, and OpenSees will compute the response of your structure to these non-uniform excitations.

Remember, when setting up, it's crucial to ensure that the ground motion records and their assignments to different parts of the model accurately represent the earthquake scenario you are trying to simulate. Additionally, the complexity of non-uniform excitation analysis means that it's often more computationally demanding, so be prepared for longer run times and possibly higher resource requirements.

OpenSees does not have a specific element type for that.

You can apply viscoelastic material properties to standard elements like quad or brick elements. OpenSees has several material models. You can use the ViscousMaterial or StandardLinearSolid material models, start from there.

I understand you're facing convergence issues with small ground motions in OpenSees. This can be tricky, but here are a few quick tips to try:

• Check Your Time Step: A smaller time step can sometimes solve convergence problems in dynamic analysis.
  
  Review Model Parameters: Make sure your material properties and boundary conditions are set correctly.
  
  Adjust Convergence Criteria: Loosen your convergence criteria a bit, especially if they're very strict.
  
  Incremental Loading: Apply ground motion gradually, starting from very small and increasing slowly.
  
  Simplify and Debug: Start with a simpler version of your model and then add complexity. This can help identify where the issue lies.

spbo Convergence issues can be a bit of a puzzle, but these steps often help sort them out. Keep experimenting, and don't hesitate to ask for advice on the OpenSees forums. Good luck!