摘要: |
Seismic response parametric studies of multi-span bridges were performed using OpenSees. The models investigated were derived from three bridge configurations (the Salinas River Bridge, the Samoa Channel Bridge, and the Eureka Channel Bridge). Nonlinear Time History Analysis (THA) was conducted for 14 input motions provided by Caltrans. The THA procedures and results are presented in this report. Results of the Equivalent Static Analysis (ESA) procedure are presented as well. To facilitate the conducted analyses, the user interface MSBridge, in which FE computations are performed using OpenSees, was further developed and employed. In the Salinas River Bridge model, the columns were modeled using the force-based Equivalent Static Analysis (ESA) (based on the plastic hinge integration method BeamWithHinges) with an idealized bi-linear moment-curvature relationship. The column foundation response was represented by p-y and t-z springs. For the Samoa Channel Bridge and the Eureka Channel Bridge models, the pier columns were modeled using the nonlinear fiber section and the force-based beam-column element with the distributed plasticity integration method (forceBeamColumn). The pier foundation response was modeled by Foundation Matrix. In all cases, an elastic abutment model was employed for simplicity. Comparison of the ESA and THA average results shows that the difference in displacement demand is about 12% for the Salinas River Bridge (for both longitudinal and transverse directions). For the Samoa Channel Bridge and the Eureka Channel Bridge models, the differences are 5.8% and 27.5%, respectively, in the longitudinal direction. The differences between the ESA and THA results in the transverse direction are 15.8% and 4.5%, respectively, for the above 2 bridges. |