Design and Seismic Response of Upgraded Outrigger Knee Joints


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Title: Design and Seismic Response of Upgraded Outrigger Knee Joints

Author(s): B. Stojadinovic´

Publication: Special Publication

Volume: 187


Appears on pages(s): 159-184

Keywords: cyclic loading; damage index; design; displacement; knee joint; seismic

Date: 6/1/1999

A comprehensive research project focused on investigation and repairing the vulnerable elevated freeway bridge structures was initiated and jointly conducted by the California Department of Transportation and the University of California at Berkeley after the 1989 Loma Prieta earthquake. One part of this project was the investigation of outrigger knee joints, a structural sub-system found in elevated freeway bridges. This investigation had two principal goals: to evaluate the behavior of existing outrigger knee joint systems under a combined transverse seismic upgrading of existing outrigger knee joints. The focus of this paper is the design procedure for seismic upgrade of existing outrigger knee joint systems. This design procedure comprises a performance objective, quantified in terms of system drift demand, and a displacement-based capacity design process that centers around an interaction for computing the level of column plastic hinge confinement pressure. To further explore the upgrade design framework. Four damage indices are examined as candidates for the role of a response measures that relates a global performance objective to a local design parameter. Directions for new research derived from this exploration are discussed in the conclusion.