PSI - Issue 44

Alberto Castellani et al. / Procedia Structural Integrity 44 (2023) 19–26 Author name / Structural Integrity Procedia 00 (2022) 000–000

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Fig. 4. Time window of the vertical acceleration at station I06. In continuous line, the original function. By small squares, the function built up from the present procedure, Eq. 8.

A smoothing is attempted by truncating the series (1) to the first 8 terms. Higher terms are likely to introduce spurious effects that might affect the representation between station and station. Rotations around the stations I06 and I12 are discussed, for which the representation of the vertical acceleration is reliable. The main frequency of both signals is around 8.2 cps (cycles per second), measured trough the time lag between peaks, in substantial agreement with the peak of the power spectrum, discussed in Castellani (2017). A correlation between the two signals is shown, with a time lag of approximately 0.058 s. The amplitude of signal at station I12 is higher than that at I06.

Fig. 5. Stations I06 and I12. Window of the time history of rotation accelerations, between 5 and 6 seconds.

6. Conclusions In a building design, the way to take into account earthquakes has been originally dictated by G. W. Housner (1959). It was based on the description of the soil motion through a Response spectrum , established in regions of suitable extension, affected by the presence of seismically active faults. Originally, the shape of spectrum has been based on no more than a tens of earthquake records, collected at stations throughout California. The soil rotation was not mentioned among the input specifications. Having made use of the recording at DAI, Smart plant in Taiwan, one important observation can be remarked, (Table 1) : in a restricted area, of 12 km 2 , the root mean square of the peak acceleration is around as high as the mean