Zhang, Wang, Fang 2022
This study investigates the performance of full-scale friction spring-based self-centering SC damper considering cumulative seismic demand. This includes consideration of mainshock-aftershock sequences and long-duration ground motions in order to observe the long-term behavior of the presented system under seismic activities. A full-scale specimen was subjected to quasi-static tests for investigation of its “fatigue” performance and hysteretic behavior of the damper in the proposed system. The results confirmed the system’s ability to generate a flag-shaped hysteretic graph and exhibit great SC capability with effective energy dissipation as load cycles increase.
System Concept
The proposed SC friction spring damper consists of a friction spring set that comprises a series of outer and inner rings. The system is designed to ensure the spring set is always subjected to compression. When exposed to load, the outer rings expand while the inner rings contract, followed by energy dissipation via friction.The friction springs are arranged in parallel to provide greater load resistance without requiring the change in size of the damper. Other components of the damper include an external tube, shim plate, ear plate, guide tubes, internal shaft and a nut fastened to the shaft.
Experimental Study, Results and Discussion
A full-scale SC damper specimen with two loading protocols was investigated by using quasi-static tests. A vertical servo-controlled actuator was placed at the top of the specimen above the loading beam and a horizontal servo-controlled actuator ensured a concentric axial load was applied. Relations between configurations such as initial stiffness, loading stiffness, unloading stiffness, and the restoring force and energy dissipation capacity of the damper were investigated.
The results demonstrated the ability of the damper to generate a stable flag-shaped hysteretic under 30 cycles of constant amplitude loading with almost no degradation during the process. The repeated cyclic loads also exhibited minimal effect on the maximum load resistance and energy dissipation during the test. According to the results, it was observed that cumulative seismic demand was always greater than the lower bound capacity, eliminating the chances of its
fatigue failure after a long duration. This validated the structural resiliency of the proposed system to multiple seismic excitations overtime.
Reference
Zhang, Ruibin, et al. “Evaluation of a Full-Scale Friction Spring-Based Self-Centering Damper Considering Cumulative Seismic Demand.” Journal of Structural Engineering, vol. 148, no. 3, Mar. 2022, p. 04021281. DOI.org (Crossref), https://doi.org/10.1061/(ASCE)ST.1943-541X.0003267