Freddi, Dimopoulos, and Karavasilis, 2020
A rocking, damage free column base with rounded edges supported with high strength post-tensioning bars and friction devices was subjected to a quasi-static cyclic load test. The test demonstrated that the system was able to perform up to the target rotation, and that any inelastic damage occurring after the target rotation was concentrated into replaceable components.
System Concept
The system consisted of a circular column base with rounded edges that was made of a hollow section welded to a steel plate. Attached to the anchor plates of the column base were bolted high strength post-tensioned bars to provide a self-centering force, as well as bolted friction devices to dissipate seismic energy. The friction devices consisted of two external steel plates bolted to an internal base plate that was welded to the section.
Experimental Study, Results, and Discussion
A 3:5 scale specimen was created to undergo quasi-static cyclic load tests. Coupon tests were performed in order to determine the characterization of the bolt forces and the initial post-tensioning force. The specimen was attached to load cells and an actuator in order to determine the forces in the post-tensioned strands and friction devices, as well as the rotation of the columns. The experiment agreed with the expected behavior that the specimen exhibited damage free behavior up to the target rotation of 0.03 radians, and that the damage that occurred after the target rotation was concentrated into replaceable components. After performing the cyclic load test, a 3D model was calibrated based on imperfections in the base plate in order to model the performance of the specimen under seismic conditions.
Reference
Freddi, F., Dimopoulos, C.A., Karavasilis, T. L. (2020). “Experimental Evaluation of a Rocking Damage-Free Steel Column Base with Friction Devices,” Journal of Structural Engineering, 146. 10, pp. 22.