Hi,
I should perform a static analysis with a variable load. Example: first analysis with 10kN load, second analysis with 15kN load etc. The position of the load is always the same.
How can I do without having to use different models several times? I tried to use the LoadCost command and create multiple analyzes with the same model but in reality at each analysis stage I add the effects of the loads. Thx.
More analysis with a single model
Re: More analysis with a single model
Dear user,
Of course in OpenSees a certain analysis starts from the previous analysis, so the effects of the loads and the non-linearity reached at the end of an analysis, will propagate to the next one.
If instead, you want to run multiple analysis on the same model, but whose effects should not propagate to the next analysis (as if they were analysis conducted on different models), you should use the reset command.
The reset command in OpenSees, tells all the elements and materials to restart from their initial stage, clearing all the non-linear effects accumulated so far.
Here is an example where I do 2 independent vertical-horizontal analysis pairs:
the first one has 2 analysis: a vertical one with N = -100 kN of vertical load, and then a pushover.
the second one has 2 analysis: a vertical one with N = -200 kN of vertical load, and then a pushover again.
As you can see from the output of the 2 horizontal analyses (stage 2 and stage 4) they restart from 0 as expected.
Here is a sample model:
Of course in OpenSees a certain analysis starts from the previous analysis, so the effects of the loads and the non-linearity reached at the end of an analysis, will propagate to the next one.
If instead, you want to run multiple analysis on the same model, but whose effects should not propagate to the next analysis (as if they were analysis conducted on different models), you should use the reset command.
The reset command in OpenSees, tells all the elements and materials to restart from their initial stage, clearing all the non-linear effects accumulated so far.
Here is an example where I do 2 independent vertical-horizontal analysis pairs:
the first one has 2 analysis: a vertical one with N = -100 kN of vertical load, and then a pushover.
the second one has 2 analysis: a vertical one with N = -200 kN of vertical load, and then a pushover again.
As you can see from the output of the 2 horizontal analyses (stage 2 and stage 4) they restart from 0 as expected.
- Immagine 2020-12-03 154137.png (13.54 KiB) Viewed 3329 times
Here is a sample model:
Re: More analysis with a single model
ok thx.. but this works only with horizontal analysis, not with vertical analysis. At the end of the stage 1 the Rfz is 100000 and at the end of the stage 3 is 300000. Because the results of the two vertical load conditions are added together. I, on the other hand, would like to have Rfz: 100000 at the end of stage 1 and Rfz: 200000 at the end of stage 3. Is it possible with reset?
Re: More analysis with a single model
ok maybe I did. In the custom command after the RESET I entered the REMOVE LOAD PATTERN command and I removed the vertical load of the first analysis.
Re: More analysis with a single model
Yes it was just a sample usage of the "reset" command to show you how to reset the internal state of a material, in order to start from a clean state.
Of course if you need, you can remove the previous load pattern
Of course if you need, you can remove the previous load pattern