Analysis of Acceleration Signal of Field-Structure Seismological Networks and Assessment of Far-field Earthquake Action in Shanghai

Abstract

The monitoring acceleration signal of field and structure is the first-hand data for assessment of earthquake action. Two field-structure seismological networks were set on different campuses of Tongji University and were put on the top floor of two tall buildings along with the field nearby. A 21-story steel-concrete composite structure and a 14-story reinforced concrete structure of two seismological networks are the tallest buildings on the two campuses. Twenty-three far-field earthquake records were obtained from October 2020 to January 2023. In this paper, the monitoring acceleration signals of the field and structure were analyzed. The actual measured amplification coefficient of the monitored structure was obtained according to the ratio of the peak value of structure signal and the ground signal, and compared with the actual response spectrum of the structure. Based on the statistical analysis of effective peak ground acceleration, the future peak level of far-field ground acceleration was obtained. The response spectrum of 5% damping ratio was obtained and found to be larger than the design spectrum curve. Corresponding to intersection point of two major regions of the spectrum curve, the characteristic period was longer than the value of 0.9s in the design code. And the spectrum curve spikes at a period of about 2.5s in the decline region. All these demonstrates double peak before and after the characteristic period in the response amplification spectrum curve, which was the basic features of the far-field earthquake action of two seismological networks. The spike of the spectrum curve in the long-period region means the amplification of long-period components in the earthquake signal. It is caused by the deep saturated covering layer in Shanghai and should be paid more attention to, especially for highly flexible structures.