Case study of the seismic response of an extra-dosed cable-stayed bridge with cable-sliding friction aseismic bearing using shake table tests

摘要

This paper presents an experimental case study of an extra-dosed cable-stayed bridge isolated by cable-sliding friction aseismic bearing (CSFAB) based on 1/20 scaled half structure multiple shake table test. The mechanical characteristics of new version CSFAB are first described in details. Then the half structure test method is introduced and validated by finite element model analyses. The test setup with 4 independent shake tables is later introduced. The test model was subjected to a suite of ground motions of increasing peak ground acceleration, first while the bridge was isolated by CSFABs and subsequently while it was isolated by conventional sliding bearings. Observation and measured seismic responses are reported. During the tests, the CSFAB system had high isolation efficiency at mild girder-pier relative seismic displacement and could restrain girder movement at excessive relative displacement. The test results also indicate self-centering capacity of CSFAB. Although the effectiveness of the restraining function of CSFAB is evident, momentary increase in girder acceleration and pier acceleration could be witnessed during the restraining, which could lead to enlarged seismic force and moment of the pier. Therefore, it is recommended that the maximum restraining force of the cables be carefully designed considering the pier strength.