Analytical study of seismic response of existing RC bridges with a variable damping ratio

Abstract

The seismic response of structures is influenced by variations in dynamic properties, which change with vibration amplitude. In this study, two

analytical models simulating experimental single-span RC bridges were developed using ABAQUS software. The connection between the slab and the pier was modeled as fixed in one case and as lead rubber bearings (LRB) in the other.Considering the equation proposed by Ghassoun et al. (2023), which describes the relationship between damping ratio and acceleration amplitude, the seismic responses of the analytical and experimental models were compared to verify the validity of this formulation. Subsequently, the proposed equation was applied to an existing RC bridge in Homs city, consisting of two spans and three piers, to investigate the influence of damping ratio variation on seismic response. The lateral displacements, accelerations, and shear forces were evaluated and compared for both constant and variable damping ratios. The results demonstrated that the numerical and analytical responses obtained using the variable damping model are in good agreement with the experimental results, with differences in the range of 1.5–2.2%, compared to 38–58% for the constant damping assumption. Furthermore, the variable damping ratio resulted in higher estimated seismic responses than the constant damping case.