Structural behaviour of a novel reusable column base connection using pinned energy dissipators

Abstract

This research introduces a novel, yet simple, column base connection that is reusable for moment resisting frames (MRFs). The proposed design incorporates a pinned energy dissipator that effectively absorbs seismic energy. Moreover, the connection utilises the self-weight of the column itself to provide a recentring force. Unlike existing self-centring column base connections, the energy dissipator in this innovative design is equipped with pins to prevent resistance to recentring caused by inelastic deformation after earthquakes. This unique feature ensures that the connection possesses self-centring capability, energy dissipation ability, and reusability. The simplified analytical models developed in this study effectively illustrate the monotonic and cyclic behaviours of the proposed connection. On the basis of the simplified model, the design procedure for the proposed connection was developed. The performance of the proposed connection was evaluated through a series of comprehensive experimental tests on specimens devised as per the design procedure. During these experiments, the rocking mechanism was successfully demonstrated, and it was observed that the failure mode primarily involved concentrated plastic deformations of the dissipative plates. All of the specimens exhibited exceptional energy dissipation and self-centring capabilities. Furthermore, the repair process simply required the replacement of the damaged dissipative plates, which proved to be advantageous in terms of cost-effectiveness and efficiency. As a result, the repaired specimens regained their load-bearing ability and seismic performance to a comparable level to the original specimens. Besides, the test results were used to validate the simplified analytical models. Further numerical studies of the proposed connection were conducted in ABAQUS. The comparisons between the finite element (FE) modelling and experimental results indicate that the proposed connection behaves in accordance with expectations, affirming the feasibility of the modelling approach. To investigate the impact of key design parameters on the global and local behaviours of the proposed connection, four groups of FE models with various parameters were constructed involving the global slenderness of the reduced section, the strength factor, the deflection angle of the dissipative plate as well as the vertical compression ratio. The parametric study focused on lateral resistance, ductility, energy dissipation capacity, and reusability. The outcomes contribute to a deeper comprehension of the assumptions and constraints of the design process, offering practical suggestions to enhance the seismic performance of the proposed connection.