Lu, Lv, Xu, 2022
In this paper, a novel system of an outrigger that improves seismic resilience and enables fast repair after residual damage. The system consists of both a self-centering and energy dissipating component and was tested under cyclic loading of scaled specimens. The proposed self-centering frictional energy dissipation outrigger (SCFO) has self-centering frictional devices (SFDs) located between the end of the steel truss and the peripheral columns. The SFD comprises sliding steel plates, high-strength bolts and combined Belleville springs. The mechanism of the steel plates and friction between them allows energy dissipation while the Belleville springs facilitates the recentering ability. The results of the cyclic loading tests on the specimens were satisfactory – demonstrating minimal damage in the structure without strength degradation, high energy dissipation capacity and self-centering capability by SFDs.
System Concept
The SCFO comprises a steel truss and SFDs. The SFD is made of two cover steel plates and two center steel plates with groove surfaces, high-strength bolts and combined preloaded Belleville springs. The cover plates consist of round holes and the center plates consist of an H-shaped stud beam with slotted holes where they are joined together by high-strength bolts and Belleville springs. The steel plates are assembled so that the groove surfaces are in contact with each other. When subjected to external force, the steel plates move along the surface and cause energy dissipation by friction. Once the external force is removed, the restoring force inside the springs recenters the cover plates to their original position moving along the slotted holes.
Experimental Study, Results and Discussion
The scaled specimens of the proposed system were tested to analyze the hysteretic behavior of the SCFO under different strength and stiffness ratios. A displacement controlled cyclic loading was applied at different amplitudes, repeated three times for each value. The results demonstrated great seismic performance of the SCFO which was supported by the flag-shaped hysteresis curves and minor residual deformation after loading. Compared to a traditional outrigger, the new proposed system had significantly lower residual deformation due to high self-centering capacity due to the Belleville springs and great energy dissipation capacity facilitated by the slip between steel plates. It was also observed that the greater strength and stiffness ratio caused greater residual deformation which limits the ratios to 0.75 strength and 0.054 stiffness ratio for a satisfactory seismic performance of the SCFO. In conclusion, with the advantage of easy repair as well as great seismic resilient properties, SCFOs proposed in this paper could be a promising alternative to traditional outriggers when resisting lateral-forces during earthquakes.
Reference
Lu, X., Lv, Z., & Xu, L. (2022). Investigation of a self-centering frictional energy dissipation outrigger equipped to supertall buildings. Journal of Building Engineering, 61, 105313.