地球与行星物理论评 (Jan 2022)
Preliminary judgment of ground motion characteristics of Yematan bridge in Qinghai Maduo M7.4 earthquake
Abstract
On May 22, 2021, an earthquake of M7.4 occurred in Maduo County, Qinghai Province, causing the collapse of the Yematan bridge and the Yematan No.2 bridge in Maduo County. According to the earthquake intensity announced by China Earthquake Administration, the earthquake intensity of the Yematan bridge is IX. However, the lack of strong seismic stations and the unrecorded time history of ground motion near the bridge is also hindering the research work on earthquake-induced failure mechanisms of the Yematan bridge. Therefore, this paper attempts to use the empirical Green's function method and refer to the concept of self-heterotopic skin transplantation in medicine to preliminarily evaluate the main characteristics of the ground motion intensity at the Yematan bridge, and try to give the possible range of peak ground acceleration (PGA) and the ground motion time history. The latest China seismic intensity table (GB/T17742—2020) and the design response spectra of the fifth generation seismic zoning map (GB18306—2015) are compared. The results show that: (1) the range of PGA (320~620 cm/s2) obtained in this paper matches well with the range of PGA (402~830 cm/s2) in China seismic intensity table (GB/T17742—2020); (2) The ground motion response spectrum synthesized matches well with the acceleration design response spectrum of extremely rare ground motions at the Yematan bridge in the fifth generation seismic zoning map (GB18306—2015), which indicates that the acceleration time history synthesized in this paper can cause the beam falling failure of the bridge. Our results show that the characteristics of ground motion intensity near the Yematan bridge are very possible and have a certain reference value. It can be used as the time history input of ground motion for the Yematan bridge and provide data support for the study of the collapse mechanism of bridge.
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