Using Pinching4 but the result is strange

[Wenyu]

You should use it in a section aggregator to represent the shear behaviour of the shear wall, while the fiber section should represent the bending behavior.

You should have a look at our beginner webinars. The last one explains this:
https://asdea.eu/software/get-started-webinars/
3D Frame Structures (Part 3) - Masonry: EFM of trilite and masonry walls

Thank you for sharing this video. I seem to understand what you mean, I also watched some modeling cases, so i made some changes. This model may still have some problems, look forward to your reply.

[ValentinaSB]

Hi Wenyu,
1. you didn't assign conditions to your model. You added it to the analysis in a constraint pattern. But it doesn't know to which point of your model you wanted to apply it. Also, you can see that after you assign conditions they will change the color, so in the future, it will help you to avoid this mistake.

Screenshot 2023-03-14 100642.jpg (162.26 KiB) Viewed 130 times

2. you used the duration 6.1 in your push analysis, I think you don't need it. You have your time path that is already 6.1. Also, check the value that you applied. You are using 1 unit force with load control.
3. you can use plain constraints in the analysis as your model is very simple.
4. check if you are coherent with the units of measure that you are using.

Best,
Valentina

[Wenyu]

Hi Wenyu,
1. you didn't assign conditions to your model. You added it to the analysis in a constraint pattern. But it doesn't know to which point of your model you wanted to apply it. Also, you can see that after you assign conditions they will change the color, so in the future, it will help you to avoid this mistake. Screenshot 2023-03-14 100642.jpg
2. you used the duration 6.1 in your push analysis, I think you don't need it. You have your time path that is already 6.1. Also, check the value that you applied. You are using 1 unit force with load control.
3. you can use plain constraints in the analysis as your model is very simple.
4. check if you are coherent with the units of measure that you are using.

Best,
Valentina

Oh My God, the first question really shouldn 't. I am too careless. If i used penalty method ,the displacement can only reach 6 mm. If i used plain constraints, the result is strange, Like the attachments. When I use penalty method, where can I modify?

[STKO Team]

try this:

fibersection.zip

(136.8 KiB) Downloaded 4 times

1) You cannot use the Plain if you impose a displacement (non-homogenous constraint)
Either penalty or transformation will work. Since you don't have complex multi-point constraints, you can use Transformation

2) You start having convergence issues when the shear law in your force-based elements go in softening. Probably the softening branch is too steep. Anyway, you can improve it by using ModifiedNewton with -initial tangent

[Wenyu]

try this:
fibersection.zip

1) You cannot use the Plain if you impose a displacement (non-homogenous constraint)
Either penalty or transformation will work. Since you don't have complex multi-point constraints, you can use Transformation

2) You start having convergence issues when the shear law in your force-based elements go in softening. Probably the softening branch is too steep. Anyway, you can improve it by using ModifiedNewton with -initial tangent

Thanks for your answer！But Whether using transformation method and modified newton or penalty method, the result is still the same as the picture. It has a tendency of hysteresis, but does not complete the cyclic loading. Actually, the maximum displacement of the experiment is 15mm. Is this because the material value I set cannot make the structure reach its due bearing capacity？

[STKO Team]

Your analysis terminated correctly (in fact it reaches 100%).
The problem is another:
Your cyclic time series has 61 points (so 60 segments) with a dt = 0.1, the total duration is 6 seconds.
But in your analysis, you set a duration of 1.0 seconds. that's why it does not complete the cycle.

Just use, in your time series, a dt = (1/60) = 0.01667:

shear.png (258.73 KiB) Viewed 94 times

[Wenyu]

Your analysis terminated correctly (in fact it reaches 100%).
The problem is another:
Your cyclic time series has 61 points (so 60 segments) with a dt = 0.1, the total duration is 6 seconds.
But in your analysis, you set a duration of 1.0 seconds. that's why it does not complete the cycle.

Just use, in your time series, a dt = (1/60) = 0.01667:

shear.png

Thank you so much！I got it. And i have another two questions:
1. As shown in the picture，The stress-strain curve of pinching4 material has an unclosed straight line at the beginning. What is the reason, Does it affect the calculation? how to modify it ?
2. I built a model of the whole house, it does not converge, I modified the algorithm，but it constantly warning ‘ForceBeamColumn3d::update - failed to get compatible element forces & deformations for element’，and not running. I have no idea to modify

[STKO Team]

1. As shown in the picture，The stress-strain curve of pinching4 material has an unclosed straight line at the beginning. What is the reason, Does it affect the calculation? how to modify it ?

It's because you are using too few sampling points. Increase the Divisions in the material tester to have more points in the chart

2. I built a model of the whole house, it does not converge, I modified the algorithm，but it constantly warning ‘ForceBeamColumn3d::update - failed to get compatible element forces & deformations for element’，and not running. I have no idea to modify

When you see that error, it probably means that some Force Beam Element has a singular section... Check the GJ in property 27!

[Wenyu]

1. As shown in the picture，The stress-strain curve of pinching4 material has an unclosed straight line at the beginning. What is the reason, Does it affect the calculation? how to modify it ?

It's because you are using too few sampling points. Increase the Divisions in the material tester to have more points in the chart

2. I built a model of the whole house, it does not converge, I modified the algorithm，but it constantly warning ‘ForceBeamColumn3d::update - failed to get compatible element forces & deformations for element’，and not running. I have no idea to modify

When you see that error, it probably means that some Force Beam Element has a singular section... Check the GJ in property 27!

Thank you so much！

[STKO Team]

You're welcome