Nonlinear Seismic Analysis of Reinforced Concrete Bridges Using the Force Analogy Method

Abstract

In this paper, a three-dimensional nonlinear dynamic analysis framework for RC bridges is established based on the force analogy method (FAM). Two biaxial local plastic mechanisms, rotation hinge (RH) and slide hinge (SH), are proposed based on the fundamental concept of FAM to simulate the nonlinear flexure-shear interactive behavior of RC piers, a critical consideration for seismic performance assessment of RC bridges. The RHs located at the ends of RC piers express the relationships of moment versus plastic rotation, whereas the SHs are assigned to simulate the shear versus plastic shear deformation behaviors of RC piers. Coupling the presented biaxial local plastic mechanisms with FAM, the nonlinear response of RC bridges under bidirectional earthquakes can be evaluated. Because only constant initial stiffness matrices are used throughout the whole analyzing process, the state space integration formulation can be used for solving the equations of motion, which makes the computational process efficient and stable. The precision of the presented biaxial local plastic mechanisms is verified against data of two tests, and a numerical example is carried out to illustrate the process of seismic analysis for RC bridges with FAM.