THE EFFECT OF REDUCED PRECISION SEISMIC INPUTS IN THE CHARACTERIZATION OF THE SEISMIC RESPONSES FREE-FIELD

The increasing demand for a better knowledge of the earthquake effects on buildings and infrastructures is prompting the scientific research to further investigate the possibility of using large nets of low cost instruments in place of just few high precision, high cost sensors installed in a limited number of locations. Contrarily, seismic monitoring activities have been so far conceived only for very special purposes (survey of strategic buildings and or sites) and traditionally curried out with a limited number of high-precision sensors. In this study, data recorded from low cost, reduced precision accelerometers have been assumed as input data to run numerical simulation and calculate local seismic responses under free field conditions. These results have been later compared with those previously obtained on the base of input data taken from high cost, high precision accelerometers instead. Local seismic responses have been calculated and compared for different combinations of several variables. In particular, several earthquakes characterized from different ground motion parameters (intensity, duration, frequency content,…) have been considered. Two different soil profiles were assumed, representing real cases; the first one is characterized by regular gradient of the geotechnical properties (Vs increasing with depth) while the second one has a stratigraphy affected by an evident singularity in the Vs profile. The two soil profiles were also characterized by different bedrock depths were the above mention seismic inputs were applied. The results from the one-dimensional, equivalent linear numerical analyses performed so far show that the local seismic responses calculated using the reduced precision seismic inputs compare well with those calculated using the seismic inputs from high precision accelerometers.