Title:
Realigning California’s I-880 Cypress Freeway
Author(s):
James E. Roberts, Tony Marquez, Carl Huang, Alfred R. Mangus, Brian Dykes, and Shawn J. Marlow
Publication:
Concrete International
Volume:
22
Issue:
1
Appears on pages(s):
33-39
Keywords:
columns; earthquake-resistant structures; post-tensioning; retrofitting; seismic analysis; soil-cement piles
DOI:
Date:
1/1/2000
Abstract:
A trestle bridge modification was required when the I-880 freeway was realigned under a Bay Area Rapid Transit concrete trestle, after the collapse of the Cypress Street viaduct in Oakland, California caused by the 1989 Loma Prieta earthquake. Seismic analysis procedures were used to prepare the plans. It was necessary to relocate the bridge’s columns, and the solution was to modify the existing trestle while it remained in place. Two longitudinal post-tensioned concrete edge beams transfer loads from the spans of the existing trestle to new cradle beams. Transverse cradle beams were cast around existing piers. After the concrete system had cured, the existing columns were removed. A pair of columns replaced each existing column removed.