Title:
Influence of Earthquake Duration on Response of Steel Jacket Retrofitted Reinforced Concrete Bridge Columns
Author(s):
Christopher J. Motter
Publication:
Symposium Paper
Volume:
364
Issue:
Appears on pages(s):
100-120
Keywords:
bridge column; Cascadia Subduction Zone; earthquake duration; loading history; loading protocol; retrofit; steel jacket
DOI:
10.14359/51745459
Date:
12/1/2024
Abstract:
Retrofit of reinforced concrete bridge columns with steel jackets is a commonly implemented strategy to increase column ductility in earthquakes. If the steel jacket retrofit is designed using available guidelines, fatigue fracture of longitudinal reinforcement is a likely cause of strength degradation. Fatigue fracture in reinforcement is dependent upon strain history in reinforcement. A model was developed to determine the strain history in longitudinal reinforcement at the plastic hinge in steel jacket retrofitted reinforced concrete columns. The model was validated with existing test data, and single degree of freedom nonlinear time history analyses were conducted using the model. Earthquake duration was shown to have a significant impact on the number of plastic excursions and the total plastic strain in the reinforcement, based on the results of analyses using an existing suite of long-duration earthquake ground motions that were each paired with a short-duration ground motion with similar response spectra. Results from analyses of 600 Magnitude-9.0 Cascadia Subduction Zone simulated site-specific ground motions for western Washington State were used in the formulation of a new testing protocol for steel jacket retrofitted reinforced concrete bridge columns that better accounts for expected demands in this region.