EDP definition

[guanxingquan]

Hi, I just have some confusions about EDP file definition:

I know that in the EDP input file, we need to define the story drift ratio in each direction in each story, peak floor acceleration in each direction at each floor level (including ground level).


I am wondering how to define the residual story drift. I went through all example input files and I haven't found any hints for residual story drift ratio.

Should I define the residual story drift ratio in each direction and in each story? or just the maximum residual drift in each direction.

I think that SP3(Seismic Performance Prediction Program) only requires the maximum residual drift (i.e., not the residual drift in each story).

[adamzs]

Hi,

Residual story drift is called Residual Interstory Drift and goes by the acronym of RID in pelicun. You can define it for each story in each direction just like you do the PID value. When evaluating irreparability, the governing value is used among the provided RID values in each story. So, if you have only one value for your building, you do not need to create two EDPs using identical drifts in them; it is sufficient to provide a single one, say 1-RID-1-1 for the first story and a similar value for each story.

SP3 works a bit differently. In pelicun, I aim to have a generic framework and treat all EDPs similarly, hence the option to provide RID values for each story. As long as you use RID only to identify irreparability, you can assign the maximum residual drift across all stories to the first story and it will work just fine.

Let me know if you have more questions.

[guanxingquan]

Thank you for your clarification, I have the following several questions and could you please help me with them?

(1) If the PID in orthogonal directions (North-South and East-West) are the same for a one-story building, should I define the same numbers for 1-PID-1-1 and 1-PID-1-2 (as shown in the attached photo) or just define 1-PID-1-1 without defining 1-PID-1-2. Similar confusions for PFA.

(2) For RID, I can have the following two options:

    (a) Define the residual story drift ratio for each story and in each direction (N-S and E-W). For example, if it is a two-story building. Then I have to define 1-RID-1-1, 1-RID-1-2, 1-RID-2-1, 1-RID-2-2.

    (b) Obtain the maximum residual story drift of the whole building and define it as 1-RID-1-1. For example, if it is a two-story building, then I can simply define 1-RID-1-1 and 1-RID-1-2 as the maximum residual story drift.

    Am I correct for the aforementioned cases (a) and (b)?

(3) When I ran loss assessment using Pelicun for a one-story building, I have eight EDPs. They are 1-PID-1-1, 1-PID-1-2, 1-PFA-0-1, 1-PFA-0-2, 1-PFA-1-1, 1-PFA-1-2, 1-RID-1-1, 1-RID-1-2. I defined the EDPs using the results from 40 nonlinear response history analyses, but I input the same numbers for the EPD in two orthogonal directions because the building has exactly the same lateral-force resisting systems in both directions. For example, I use the same numbers for 1-PID-1-1 and 1-PID-1-2. However, the Pelicun gives me the following warning:

"The number of samples is not sufficient to estimate the correlation matrix. We assume uncorrelated EDPs".

According to my understanding, 40 NRHAs is enough to estimate the correlation matrix, but I still get this warning.

[adamzs]

(1)
The directions (the last number in the ID) you use when defining EDPs shall correspond to the directions you use in the Performance Model. If you define the performance model with components in both directions, in general, you are expected to provide EDPs in both directions.

If you only have EDPs in one direction, you can either i) use only one direction and assign all components to that direction in the performance model; or ii) use identical data for the two directions - as you suggested - and have a more realistic performance model with components assigned to two directions in the building. Both approaches are supported and should provide identical results.

Floor accelerations are special because the corresponding components are almost always non-directional, i.e., their damage is controlled by the governing acceleration value across all horizontal directions. In such a case, the direction of the component is not important. In the current release, I recommend using '1' as the direction for such components. In a future release I will make the direction attribute optional, so that these components will not request such information.
When you only have PFA in one direction, use 1-PFA-1-1 (or replace the penultimate ID with the appropriate floor number) and there is no need to provide an identical second column. If you have PFA in more than one direcion, provide all columns; pelicun will take the governing value automatically in the background.

(2)

You are correct, both cases should work as long as you use the RID to evaluate irreparability.

(3)

The warning you receive is posted if the sample covariance matrix of the EDPs is not positive semidefinite. This can typically happen when the number of available samples is less than the number of EDPs. In many of those cases, the covariance matrix is rank-deficient, but still positive semidefinite and we can handle that, so you see no error.
I agree with you that it is unexpected to observe such behavior if you provide 40 samples across 8 EDPs, so this might be a bug.

Would you mind sending me a private message with a sample of the EDP data that leads to this behavior? I could use that to find the bug.

Thanks!