Performance of a Damage Protected Highway Bridge Pier Subjected to Bidirectional Earthquake Attack
Recent earthquakes such as Loma Prieta, Northridge, and Kobe have demonstrated a need for a new design philosophy of bridge piers that avoids damage in order to ensure post-earthquake serviceability and reduce financial loss. Damage Avoidance Design (DAD) is one such emerging philosophy that meets these objectives. DAD details require armoring of the joints; this eliminates the formation of plastic hinges. Seismic input energy is dissipated by rocking coupled with supplemental energy dissipation devices. In this paper the theoretical performance of a DAD bridge pier is validated through bi-directional quasi-static and pseudodynamic tests performed on a 30% scale specimen. The DAD pier is designed to rock on steel-steel armored interfaces. Tension-only energy dissipaters are used to increase tie down forces and further reduce dynamic response. The seismic performance of the DAD pier is compared to that of a conventional ductile pier. Results show that one can have 90 percent confidence that the DAD pier will survive a design basis earthquake without sustaining any damage, whereas for the conventional design substantial damage is sustained.