Evaluation and Upgrading of Outrigger Knee Joints

Abstract

The catastrophic collapse of the old Cypress Viaduct during the Loma Prieta 1989 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: (1) to evaluate the behavior of the existing outrigger knee joint subassemblies under a combined transverse and longitudinal loading and (2) to devise and experimentally verify upgrading strategies and repair techniques suitable for application on the existing elevated freeways. 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.