Quasi-static cyclic loading experiment and analysis of mechanical properties of the Sc-FSB

In order to improve the seismic performance of a continuous bridge, we propose to install self-centering functional separation bearings (Sc-FSB) between the fixed pier and the girder in the bridge. Following the design idea of separating functionalities, the Sc-FSB device is primarily composed of a sliding bearing to bear vertical load, a friction cable to carry horizontal seismic force and dissipate the seismic energy input into the superstructure, and self-centering springs to achieve post-earthquake self-centering effects. In this study, the Sc-FSB device's hysteretic model is established, and its theoretical formula is deduced. The quasi-static cyclic tests of 10 Sc-FSB device specimens were performed to verify their promising mechanical performances, in which we consider parameters of two friction cables with different diameters and three self-centering springs with different stiffnesses. The results show that the Sc-FSB device holds excellent characteristics of a typical friction damper, such as relatively stable outputs, good energy dissipation and deformation capacity under all working conditions, and its fatigue performance meets the requirements of typical specifications. In addition, several unique features of the Sc-FSB are identified as follows. The maximum damping force is independent of the loading frequency, and it increases with the displacement amplitude. The damping force is significantly affected by the pre-tension force of the friction cable and the number of winding coils, and as a result, the energy dissipation performance is promising. The stiffness and pre-tension force of the self-centering spring significantly improve the self-centering ability of the Sc-FSB device. The design of friction cable and self-centering spring effectively separates the functions of bearings. This study can serve as a foundation for the further study of Sc-FSB device and as a reference for the research of other similar friction dampers.