Novel Isolation Device for Protection of Cable-Stayed Bridges against Near-Fault Earthquakes

Abstract

This paper investigates the near-fault (NF) seismic performance of a novel isolation system, referred to as the roll-n-cage (RNC) isolator, considering the cable-stayed Bill Emerson Memorial Bridge in Missouri. The RNC isolator is designed to achieve a balance in controlling bridge displacement demands, structural accelerations, and internal forces in the tower attributable to horizontal seismic forces. It provides in a single unit all the necessary functions of rigid support, horizontal flexibility with enhanced stability, and energy-dissipation characteristics. Moreover, it has two unique features that are built-in: energy-absorbing buffer and linear recentering mechanisms. Through a nonlinear time history analysis under three recorded NF earthquakes and three synthetic ground accelerations, the results show that the RNC isolator is a convenient isolation system in protecting cable-stayed bridges against NF earthquakes.