RESPONSE OF SEISMIC ISOLATED ELEVATED BRIDGE DUE TO SLIGHTLY STRONG EARTHQUAKES IN 1995 AND 2018

Abstract

This paper studies the behavior of seismic isolated structure (Pier 408 of Matsunohama Viaduct) under slightly strong earthquakes (M4.0-6.9) with seismic acceleration data recorded in the 1995 Kobe Earthquake and the 2018 Osaka Earthquake. The target structure was modeled by a 1DOF model with two parameters (stiffness and damping ratio) which are to be determined. The damping ratio is estimated using the Random Decrement Technique (RDT). Multiple numerical simulations are carried out with different preset stiffness to obtain the acceleration responses of the structure, which are later compared with observed results to calculate the RMS value. The model with minimum RMS value is considered to have stiffness closest to reality. Results show that the system identification technique works fine and the stiffness of the lead rubber bearings (LRBs) becomes larger in 23 years.