Seismic Performance Design Criteria Of Existing Bridge Bent Plastic Hinge Region And Rapid Repair Measures Of Earthquake Damaged Bridges Considering Future Resilience

The main objective of this research was to evaluate the seismic performance of existing sub-standard reinforced concrete (RC) bridge column-spread footing subassemblies and to quantify the material strain limits through a full-scale experimental program. A total of six column-footing test specimens with pre-1990 construction details were subjected to reverse cyclic lateral loading, utilizing a conventional three-cycle symmetric loading protocol and a protocol representing the demands expected from a CSZ earthquake. Additionally, the tests were designed so that variable axial loading could be applied to simulate the secondary load effects experienced during an earthquake in a column that is part of a multi-column bent. A rapid repair method incorporating semi-permanent installation was also developed, anticipating the need for quick measures following the Cascadia Subduction Zone (CSZ) earthquake, which is expected to damage the existing bridges in the Pacific Northwest and spread geographically throughout the region. The proposed repair methodology uses capacity design principles to protect the remainder of the bridge from future earthquakes and eradicates the need for establishing rebar continuity, resulting in a less labor-intensive repair method. The adopted concept is to utilize U-shaped metallic plates as externally attached ductile fuses to be anchored to the non-damaged part of the column, hence bypassing the damaged zone to restore the lateral capacity.