Improvement of the Performance-Based Seismic Design Method of Cable Supported Bridges with the Resilient-Friction Base Isolation Systems

Abstract

In areas of civil engineering, the resilient friction base isolator (R-FBI) system has been used due to its enhanced isolation performance under seismic excitations. However, because nonlinear behavior of the R-FBI should be reflected in seismic design, effective stiffness (Keff) of the R-FBI is uniformly applied at both peak ground acceleration (PGA) of 0.08 g and 0.154 g which use a multimodal response spectrum (RS) method analysis. For rational seismic design of bridges, it should be required to evaluate the dynamics of the R-FBI from in-field tests and to improve the seismic design procedure based on the performance level of the bridges. The objective of this study is to evaluate the dynamics of the R-FBI and to suggest the performance-based seismic design method for cable-supported bridges with the R-FBI. From the comparison between the experiments’ results and modal shape analyses, the modal shape analyses using primary (Ku) or infinite stiffness (fixed end) showed a great agreement with the experimental results compared to the application of Keff in the shape analysis. Additionally, the RS or nonlinear time history method analyses by the PGA levels should be applied by reflecting the dynamic characteristics of the R-FBI for the reasonable and efficient seismic design.

Comparing Rubber Bearings and Eradi-Quake System for Seismic Isolation of Bridges

“…Compared to a traditional non-isolated structure, seismic isolation can reduce the forces and displacements in the structure by up to 75% that allow the structure to remain functional with less or no damage. The cost saving brought by the seismic isolation is achieved by the possibility to reduce the dimensions of the foundation by dropping the elastic forces down by up to 75% in the design [ 1 , 2 , 3 , 4 ].…”

“…The lateral Mass Energy Regulator (MER) springs that supply restoring forces primarily reposition the plate back to its original position after finishing displacement responses. EQS transfers the seismic energy into heat and spring energy through friction of a PTFE disc pad and MER [ 2 , 6 , 7 , 8 , 15 , 16 , 17 , 18 , 19 , 20 , 21 ]. Whereas the rubber bearings exhibit relatively significant dispersion in their mechanical parameters, EQS can be tuned to the desired level of stiffness and damping, and generally has a force–displacement relationship presenting post-yield stiffness-hardening during large inelastic displacement.…”