Author Topic: User defined input motions and rigid halfspace definition  (Read 917 times)

cysorianoc

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User defined input motions and rigid halfspace definition
« on: June 10, 2021, 01:41:30 AM »
Hello everyone,

O recently found this very interesting software, I gave the first look at some of the features, but I got confused about how to load user-defined input motions, according to the example files it is necessary to create some .json files and I am not familiar with them.

Is it there any tutorial to specifically create those .json files, are there in what units, velocity units ?. And probably for future versions, it would be useful to implement a way to load user-defined motions maybe as .csv files. Another question is if is there any option to define a rigid halfspace ?.

Best regards.

charles

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Re: User defined input motions and rigid halfspace definition
« Reply #1 on: June 11, 2021, 04:36:38 AM »
Hello, thanks for your interest.

We choose to use json format because it provides a human-friendly format suitable for encapsulating all the information for defining the ground motion in a single file. 
It is a simple text file, you can edit using any text editor.
Let me use this example to explain: https://nheri-simcenter.github.io/s3hark-Documentation/_downloads/3998362659b66102f79aa5f88ada16e0/SRT-GM-Input-Style3-full.json
If you open it, you'll see its structure like shown in the attached figure.
You only need to change a few things to fit for your data:
1. You can see the type of this motion is "UniformVelocity",  which means in the "data" section, you should input velocity values.
2. "numSteps" = 7998, it means there should be 7889 values in the "data" section.
3. In the units section, you only need to change the 'length' unit to either "in" or "m", means inch or meter. So the unit of the "data" is in/sec or m/sec, depending on the 'length' unit you choose
4. "dT" means the interval between the "data" values, dT's unit in this example is second, because you "time":"sec"

To account for the finite rigidity of the underlying half-space (bed rock), a Lysmer-Kuhlemeyer (1969) dashpot is incorporated at the base of the soil column.

Let me know if I answered your question.

cysorianoc

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Re: User defined input motions and rigid halfspace definition
« Reply #2 on: June 14, 2021, 03:22:27 PM »
Thank you very much for your reply,

Just a couple more questions, in the case of a rigid halfspace, is it there any configuration ? or in this case it would be necessary to increase the bedrock Vs and Density ? I am intending to simulate the response of a centrifuge experiment, so the base could be considered as a rigid halfspace.

And a second question is related about extracting the data from the simulations, I watched one of the tutorial videos in which there is a MATLAB file to extract and process the data, are those MATLAB files available anywhere ?

Best regards.

charles

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Re: User defined input motions and rigid halfspace definition
« Reply #3 on: June 22, 2021, 10:07:23 PM »
Hello,

Yes, the parameters of the dashpot can be defined: the 'Rock' layer's Density and Vs can be changed. See the attached img.
The matlab files are attached.