Processing Data from Vibration Recordings

Abstract

The article aims to present a way of processing the data within a real-time transmission system of recorded vibration. At present, Romanian National Strong Motion Network for Constructions of URBAN-INCERC has 56 seismic / digital accelerometer stations, of which 46 are in territory and 10 in Bucharest. The seismic stations of this system are placed in some ground floor-buildings type, assimilated with the free-field, or in buildings with 1-3 levels. First application of the real-time transmission system is related to the accelerometric records from moderate earthquakes, which have shown a spatial distribution of PGA with NE-SW directivity, similar to that observed under certain conditions of seismic severity in previous strong earthquakes. Some charts illustrating the acceleration amplitudes recorded from the 2016 and 2017 earthquakes in the URBAN-INCERC network will be shown. The second application is referred to the structural response (structural behaviour under ambient vibrations or moderate and severe seismic motions). Generally, the spectral analysis of these records leads to getting: the natural frequencies, the influence of the general directivity of waves propagation specific to the Vrancea source (on the spectral content and on structural response), the influence of the local soil conditions etc. In this case, for a study building, the vibration modes, the drift/the relative floor displacement etc. can result from this processing, with a validation based on a structural modelling with finite elements. The seismic wave propagation direction is the first option for determining the direction of propagation of severe effects on buildings. The correlation between them can be validated by the existence of pre-event dynamic characteristics of those buildings (before a major seismic event) and at post-event time.