Seismic Analysis and Protection of Highway Bridges Including Soil-Structure Interaction I

Speaker:
Jian Zhang
Department of Civil Engineering
University of California Los AngelesAbstract: This seminar presents results from my doctoral studies that examine the efficiency of supplemental energy dissipation devices to suppress the seismic response of highway bridges. Recognizing that soil-structure interaction affects appreciably the earthquake response of highway overcrossings, the study concentrates on the development and validation of a simple yet dependable method to estimate the seismic response of freeway overcrossings. Firstly, approximate analytical solutions and finite element results are compared to conclude on a simple procedure that allows for the estimation of the kinematic response functions and dynamic stiffnesses of approach embankments. Secondly, the study proceeds with the validation of a step- by-step analysis procedure through two case studies of instrumented conventional highway bridges. The proposed method adopts the substructure approach where all dynamic stiffnesses of approach embankments and pile groups are approximated with frequency-independent springs and dashpots. Excellent agreement between the simulated and recorded response has been achieved using the proposed procedure. Finally, the proposed procedure is used to analyze the seismic response of a newly constructed freeway overcrossing that is equipped with energy dissipation devices. The nonlinear behavior of columns as well as hysteretic behavior of seismic protection devices (elastomeric bearings and viscous fluid dampers) are included. The emphasis is placed to understand the effect of supplemental damping in association with the ability of the structure to dissipate energy through soil-structure-interaction. It is concluded that the as-built supplemental energy dissipation devices are partially effective in controlling displacement demands for this model bridge when soil-structure-interaction effect is included. In some occasions the bridge with protection devices under performs the bridge with conventional design (i.e. integral abutment). Soil-structure interaction is partially responsible for reducing the efficiency of the protection devices. --------------------------------------------------------------------------------

Location: Kaprielian Hall (KAP) - 203

Audiences: Everyone Is Invited

Contact: Evangeline Reyes