Inelastic Response of the Cypress Viaduct to the Loma Prieta Earthquake.
Inelastic Response of the Cypress Viaduct to the Loma
Kunnath, S. K.; Gross, J. L.
Engineering Structures, Vol. 17, No. 7, 485-493, 1995.
bridges (structures); damage evaluation; dynamic
response; highways; elevated highway structures; failure
analysis; modeling; reinforced concretes; seismic
The inelastic damage evaluation of a typical double-deck
bent of the Cypress Viaduct which collapsed during the
1989 Loma Prieta earthquake is presented. A model of
the bent consisting of spread plasticity-based
beam-column elements to represent the piers and deck,
and shear panel elements to represent the pedestal
region was developed. To accurately determine beam and
column moment-curvature relationships, separate computer
analyses using an element fibre model 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. The
results of time-history analyses, which include a
prediction of member damage, indicate that collapse was
initiated by a shear failure of the pedestal regions.