Report No.: CCEER-95-6
Nonlinear Seismic Response Analysis of Isolated Bridges with Multiple
Columns
Authors: G. Griffin, M. Saiidi, and E. Maragakis
Date: November 1995
- Performing Organization:
- Department of Civil Engineering/258
- University of Nevada, Reno
- Reno, NV 89557
- Abstract:
- A nonlinear computer program to predict the dynamic response of base isolated bridges to
orthogonal, horizontal earthquake ground motions was developed. The computer program can
model multi-span bridges with straight, continuous superstructures and multi-column bents.
Hysteretic behavior of elastomeric or lead-rubber isolators, abutments, shear keys, and
columns can be modeled. Nonlinear analysis of the six-span Verdi bridge near Reno, Nevada
showed that column ductility demands can be eliminated using isolation. Contrary to linear
elastic theory, the superstructure displacements were controlled. Studies were conducted
to show that seismic isolation may not be effective in bridges with long columns and
located on deep soil deposits. The AASHTO Guide Specifications for Seismic Isolation
Design were evaluated. Results of the simplified linear methods compared well with
nonlinear analysis in the longitudinal direction but were in error by 21% transversely
(Abstract by authors).