Application of Inelastic Damage Analysis to Double-Deck Highway Structures

摘要

The Loma Prieta earthquake of October 17, 1989, caused extensive damage to manyhighway structures and particularly to double-deck structures. The most notable was the collapse of the Cypress Viaduct (Interstate 880). A study was undertaken by NIST to identify, using computer-based analysis methods, causes of structural failure of elevated highway structures resulting from the Loma Prieta earthquake and thereby reveal the potential for damage or collapse of similar structures nationwide. The IDARC analysis program, developed at the University of Buffalo, was used in the inelastic seismic analysis. Features of the program and enhancements incorporated to model the Cypress Viaduct structure are described. To accurately determine beam and column moment-curvature relationships, separate computer analyses were conducted. In addition, a smeared-crack approach finite element analysis was employed to determine the lateral load-deformation relationship of the pedestal regions. The model of the Cypress Viaduct was subjected to the Oakland Outer Harbor Wharf ground acceleration record in the plane of the bent. The analytical model was calibrated using static lateral load tests, ambient and forced vibration tests, and observed performance.