# 2019 Q & A

## Question 1: Regarding the calculation of the the parameter Mave, are M1(t), M3(t), M4(t), M6(t) vectors (ux,uy) or total displacements (sqrt(ux^2+uy^2))? I.e. if the motion is pure torsion, Mave=0?

Answer: M1(t)=sqrt [ux1(t)^2 + uy1(t)^2], where ux1(t) and uy1(t) are the x and y displacements of point M1 at time t. Same definition is also valid for points M3, M4 and M6.

In the case of pure torsion, Mave is not zero as M1, M3, M4 and M6 are always positive according to the above definition.

Mave can be interpreted as a measure of how close the response is to overturning.

## Question 2: There is an offset from zero in the beginning of some of the input accelerations, should we remove it?

Answer: Yes any offset may be removed. This can be done by subtracting the average of the first few points (e.g. 10) from the complete acceleration time history, or any other correction method the contestants prefer.

Please note that the provided input motions have already been filtered with a low pass 8 pole Butterworth filter with a cut-off frequency of 1400Hz. The contestants are expected to make any further corrections (baseline correction, filtering, etc) that they feel necessary.

## Question 3: Regarding the acceleration data you provided, we found 225000 data instead of what you declared 22500. Does this mean that the sampling rate is 0.0002s?

Answer: That is correct, there was a typo in the rules document. Number of data is 225000 and the dt=0.0002 s. The rules document is also updated accordingly.

## Question 4: Regarding the acceleration data you provided, the third column (which correspond to accelerations in the vertical direction) is only noise, correct?

Answer: During the applied motions, the table was supposed to move only in the horizontal plane. However, there is an unavoidable vertical motion too, so this is why the acceleration in the vertical (z) direction is non-zero. The spikes in the vertical direction might correspond to vertical accelerations caused by the impact of the specimen on the table.

## Question 5: I have noted that the signal inputs for run# 157 and 158 are exactly the same. I Just wanted to double check if this has been done on purpose or not.

Answer: That is correct, the signal inputs for runs 157 and 158 are exactly the same. Therefore, contestants are expected to submit the same result for runs 157 and 158. Organizing committee will evaluate whether Run 158 results will be used in the scoring.

## Question 6: The ground motion #3 (ug3.txt) seems to contain only some noise and no recorded data. Can you confirm that something is wrong with this file or that everything is ok and it should be considered as is?

Answer: Yes this file contains noise, however contestants can submit a result for this run. Organizing committee will evaluate whether the results of this run will be used in the scoring.