FORCE FROM REACTION VS COUNTER REACTIONS. Control of support removal time.

[Sylwester]

Dear STKO,
I want to do an analysis of the removal of the support over time and get the results as in the example shown.

beam.jpg (39.09 KiB) Viewed 3161 times

removing 1.001 s.jpg (231.41 KiB) Viewed 3161 times

I have put 2 files under the post:
1) I used the Force From Reaction command and made the calculation according to the topic on the forum: viewtopic.php?f=33&t=1752
2) In the place of removing the support, I inserted the value of the previously calculated reaction and counterreaction.
In this model I want to perform the procedure described in the picture:

procedure.jpg (2.89 MiB) Viewed 3161 times

My questions are:
1) In the first model (force from reaction), can I control the time of removal of the support? Is the removal of the support sudden and in one time step?

2) In model two, I did not know how to define the time series . From an earlier forum post it was described that I should create a time series command twice.

My preliminary guess is that in the case of the first one there will be no possibility to control the time of removing the support.

My main goal is model 2 and, first of all, to perform analyses depending on the support removal time (tr). For example, what will be the displacement in support B for tr = 0.10 s and what for tr = 0.18 s as in the attached picture. Am I able in STKO to carry out simultaneous analysis of carrying out an analysis of the removal of the column for different tr? So as to obtain on one diagram displacements depending on different tr (figure 5.22)

different tr.jpg (4.15 MiB) Viewed 3161 times

I will be very grateful for your help
Best regards
Sylwester

[STKO Team]

Actually, it is enough to just remove the support. However in this case you cannot control the duration of the removal (it will coincide with the time step).

The alternative is to use the force-from-reaction to automatically compute the reaction of the removed constraint. Then you can give it a Path time series that goes from 1 (100% of the reaction) to 0 (full removal) over a given time step.

If you want to do it parametrically, you can use the Python API in STKO (if you don't know how to use it, please watch the webinar #20 Intro to STKO v2.0's Python API.

Here's a file with the second approach:

MODEL 1 FORCE FROM REACTION.zip

(132.67 KiB) Downloaded 195 times

Here's a python script that runs your analysis parametrically:

ParametricRemovalTime.zip

(1.21 KiB) Downloaded 190 times

Here's what you get:

param.png (308.96 KiB) Viewed 3103 times

[Sylwester]

Actually, it is enough to just remove the support. However in this case you cannot control the duration of the removal (it will coincide with the time step).

The alternative is to use the force-from-reaction to automatically compute the reaction of the removed constraint. Then you can give it a Path time series that goes from 1 (100% of the reaction) to 0 (full removal) over a given time step.

If you want to do it parametrically, you can use the Python API in STKO (if you don't know how to use it, please watch the webinar #20 Intro to STKO v2.0's Python API.

Here's a file with the second approach:
MODEL 1 FORCE FROM REACTION.zip

Here's a python script that runs your analysis parametrically:
ParametricRemovalTime.zip

Here's what you get:
param.png

Thank you very much. This will save me a lot of time. I have a small problem with the script editor. When I open the PY. file in STKO I get an empty script. On the other hand, if I run the analysis everything works, but I can't edit the script because I can't see it. Is this a STKO bug?

error.jpg (93.13 KiB) Viewed 3056 times

[STKO Team]

Don't put scripts in folders with special characters. In general, do not use folders or file names with special characters in STKO. They can give problems.

(from the image I can see a "O" with an acute accent)

[Sylwester]

Actually, it is enough to just remove the support. However in this case you cannot control the duration of the removal (it will coincide with the time step).

The alternative is to use the force-from-reaction to automatically compute the reaction of the removed constraint. Then you can give it a Path time series that goes from 1 (100% of the reaction) to 0 (full removal) over a given time step.

If you want to do it parametrically, you can use the Python API in STKO (if you don't know how to use it, please watch the webinar #20 Intro to STKO v2.0's Python API.

Here's a file with the second approach:
MODEL 1 FORCE FROM REACTION.zip

Here's a python script that runs your analysis parametrically:
ParametricRemovalTime.zip

Here's what you get:
param.png

Dear STKO,
Thanks to your help, I have carried out the above calculations for a reinforced concrete slab in which I am removing the corner column.
I wanted to ask for your help in slightly modifying my model.

In the above model I would like to remove another column (any column), with the same force from reaction procedure.

Specifically, I would like to achieve this effect:
1. perform a static analysis
2. remove the first column for a specific tr (time removal)
3. remove the second column at a time, e.g. 2 s after starting to remove the first column.

I don't know how to model the effect of removing the second column after the selected time to start removing the first column.

Do I need to create a new load path for procedure 3? Do I need to create a 3rd dynamic analysis command?

Best regards

[Sylwester]

Dear STKO
I made a model in which 2 columns are removed, added another time seriespath, with functions startTime.
No matter what time I type the response of the structure is the same.
Do I need to do 2 transient type analysis?

2 columns.rar

(123.55 KiB) Downloaded 84 times

[STKO Team]

Try this:

2 columns.zip

(172.83 KiB) Downloaded 74 times

It's because the 2nd time series starts at 0.5, but everything before the start time is assumed 0. So your second column is first suddenly removes, then suddenly applied at t = 0.5+0.35 and then progressively removed.

A side note:
This approach of replacing a column with the counter-reaction can be acceptable for the removal of a single column, but not with multiple columns.
When you remove the first column, the load of the slab should redistributed over 3 columns, increasing their reactions.

To account for this, you can first remove the SP of the 1st column, do your removal procedure with the counter-reaction, then remove the SP of the second column and do it again

[Sylwester]

Try this: 2 columns.zip

Thanks for the model.
I don't understand controlling the start of the removal time of the second column. I see that in the newTimeseries.Path that you made I can set a diifferent dt and this is nice, But when is the second counter-reaction really applied?

Ther is a modification in the list of values and you set tStart =0.
I specifically gave 2 monitors, one for each column being removed, to show that the displacements on the second removed column at the beginninig of the transient analysis are constant, and increase later (for example after 2 s assuming that the entire transient analysis takes 5s).

In this case should I put the 2s to the tStart? (where now is 0?)

To account for this, you can first remove the SP of the 1st column, do your removal procedure with the counter-reaction, then remove the SP of the second column and do it again

Please correct my algorithm if I am wrong
1. Static anlyses With the same model as it is now
2. Remove SP (only 1 column) (In the attached model i have both columns)
3. Load paterrn forcfromreaction (1 column, the firts timeSeries Path)
4. Remove SP (2 column)
5. Load paterrn forcfromreaction (2 column, the second timeSeries Path)
6 Transient

Or between points 3 and 4 additional analysis ?

1. Static anlyses With the same model as it is now
2. Remove SP (only 1 column) (In the attached model i have both columns)
3. Load paterrn forcfromreaction (1 column, the firts timeSeries Path)
4. Transient
5. Remove SP (2 column)
6. Load paterrn forcfromreaction (2 column, the second timeSeries Path)
7. Transient.

[STKO Team]

I don't understand controlling the start of the removal time of the second column. I see that in the newTimeseries.Path that you made I can set a diifferent dt and this is nice, But when is the second counter-reaction really applied?

I changed the time series so that the reaction of the second column starts decreasing when the reaction of the first column is zero.
But as I said this is not 100% correct, because in reality, when column 1 is removed, the slabe should redistribute its loads to the remaining 3 columns, that's why you have to remove them progressively

Or between points 3 and 4 additional analysis ?
1. Static anlyses With the same model as it is now
2. Remove SP (only 1 column) (In the attached model i have both columns)
3. Load paterrn forcfromreaction (1 column, the firts timeSeries Path)
4. Transient
5. Remove SP (2 column)
6. Load paterrn forcfromreaction (2 column, the second timeSeries Path)
7. Transient.

If yo do it like this, and in the analysis at point 4 you reset the time to 0, you can simply use the same timeSeries for both load patterns

[Sylwester]

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