Title: Evaluation and Upgrading of Outrigger Knee Joints
Author(s): Christopher R. Thewalt and Bozidar Stajadinovic
Publication: Symposium Paper
Appears on pages(s): 275-298
Keywords: biaxial loads; bridges (structures); columns (supports); earthquake-resistant structures; evaluation; joints (junctions); reinforced concrete; reinforcing steels; Construction
The catastrophic collapse of the old Cypress Viaduct during the 1989 Loma Prieta earthquake emphasized the vulnerability of elevated freeway bridge structures. One track of the joint Caltrans and University of California, Berkeley, research project is the investigation of outrigger knee joints found in elevated freeway bents. This project has two principal goals: to evaluated the behavior of the existing outrigger knee joint subassemblies under a combined transverse and longitudinal loading and to devise and experimentally verify upgrading strategies and repair techniques suitable for application on the existing elevated freeways. The performance of the existing outrigger knee joint subassemblies was evaluated by testing two as-built models. After considering several upgrading strategies, two were tested on the remaining five specimens. In parallel with the experiments, a set of tools was developed for design and analysis of the upgraded subassemblies. A summary of the design, analytical, and experimental work conducted to date is presented in this paper.