Title: Impact of Confinement on Bar Anchorage in Relocated Plastic Hinges

Author(s): Taylor J. Brodbeck, Zachary A. Shurow, Rudolf Seracino, Mervyn J. Kowalsky

Publication: Structural Journal

Volume:

Issue:

Appears on pages(s):

Keywords: performance-based design; reinforced concrete; repair and strengthening; seismic design

DOI: 10.14359/51740459

Date: 1/23/2024

Abstract:
Bridges subjected to extreme damage from earthquakes are usually considered unrepairable and therefore must be replaced. One location where damage is concentrated in reinforced concrete bridges is in the plastic hinges that form at the ends of columns where the moment demand is the largest, causing buckling or fracture of the reinforcement. Recent studies have shown that plastic hinge relocation can restore reinforced concrete columns to their original force and displacement capacities. In this repair, a plastic hinge damaged by a seismic event is strengthened so that in subsequent seismic events, the damage will form in an undamaged section, ensuring a ductile response. The aim of this research is to improve the constructability and performance of the repair using a steel jacket. Tests were conducted on columns subjected to reverse cyclic loading, repaired, and re-tested. A bolted connection simplified construction. Research has shown that the repair’s response is weakened when fractured bars in the original plastic hinge debond. In these tests, anchorage and bond conditions were improved by increasing the confining stresses by using a larger jacket thickness. This enhanced the seismic resilience, evidenced by an increase in the dissipation of energy and a reduction in strength degradation.