Q6.6: What is the model of the accelerometers that will be used during the competition?
A: The product information for the accelerometers that will likely be used at the competition can be found at the following link: https://www.te.com/usa-en/product-4030-006-120.html
Q6.5: Regarding the following statement: “Digitally high-pass filter the acceleration recordings in the frequency domain using a 3rd order Butterworth filter with a corner frequency of 0.8 Hz.” Why is the Butterworth filter applied to the Fourier transform of the signal and not the signal itself? Shouldn’t a Fourier filter be applied to a Fourier transform instead of a Butterworth filter? Could the thought process for doing this sort of filtering be explained?
A: The Butterworth filter should be applied to the signal itself in the time domain, not the amplitude spectrum in the frequency domain. The wording is incorrect in Section 6.7 and will be amended. It is recommended, however, to look at the response of the signal in the frequency domain to understand why a Butterworth […]
Q6.4: Can temporary 3D printed supports be used to hold washers and plates while the threaded rod is installed?
A: Temporary 3D printed supports may be used as long as they are placed and removed within the dead load installation time limit described in Section 6.4a. After the dead load installation time has expired, dead loads must be secured to the structure only through the methods described in Section 6.4a.
Q6.3: In the text file, the spectral velocity and displacement is given in units of cm/s and cm. Is the g for spectral acceleration in cm/s^2 as well instead of the standard m/s^2?
A: The Sa values are in terms of “g” – acceleration due to gravity. Multiply values by “g” (= 9.81 m/s^2) to obtain Sa in m/s^2.
Q6.2: In Section 6.1 of the official rules, it states that “Structures will be subjected to 2 scaled and modified ground motions”. How does SDC intend on scaling/modifying ground motions for the shake table that will be used during competition? In order to successfully scale the ground motions to our shake table, we plan to choose between preserving acceleration, preserving impulse experienced, or preserving frequency as given by the power spectral density of the ground motion data. Which of these options will give ground motions that are the most similar to the ones used on the competition shake table?
A: The ground motions posted in the zip file on the competition website are already modified and scaled. These acceleration time histories will be input directly to the shake table.