Cost-effective post-tensioned bridge pier with internal dissipation

This paper presents the development and testing of a novel internal dissipation connection for the use of post-tensioned rocking columns. The solution is one of the many referring to the dissipative controlled rocking (DCR) bridge design philosophy. The internal dissipaters are carefully designed to be cost-effective and reduce the overall construction cost. The dissipaters are fully threaded, Grade 300 bars connected to the permanent column and foundation longitudinal reinforcement with threaded couplers. In this research, a DCR column is subjected to subsequent earthquake events, and the dissipaters' strain design limits are chosen such that there is no need for replacing after a significant seismic event. The result is a recommended design strain limit of 1.5% for the dissipaters that guarantees the structural integrity of the DCR column after a seismic event. Additionally, a cumulated strain of 5% is recommended for the dissipaters before replacement is suggested. The proposed connection detailing with replaceable internal dissipaters, combined with post-tensioned high strength bars and well-confined concrete, provided self-centring capabilities (no residual displacement), dissipation capacity and significantly less damage in the bridge column than a traditional reinforced concrete solution.