Seismic behavior of the main girder of a bridge with viscoelastic dampers

Introduction. The seismic stability of bearing structures is one of the main objectives of design and construction of structures in earthquake areas. The co-authors have analyzed the effect of a damper, located at the intersection of structural elements, on the seismic response of the main girder of a steel-concrete bridge exposed to the seismic impact. The purpose of this study is to select optimal values of viscous and elastic elements to ensure the seismic resistance of the bridge. Materials and methods. The finite element method was used to simulate the geometric characteristics of the bridge. The model of the bridge has rod elements to simulate girders and viscous elastic elements to simulate dampers. In the study, different values of elastic and viscous characteristics of the damper were used in pairs. The nonlinear problem statement helped to analyze the bridge structure using the direct dynamic method. Results. As a result, we obtained a graphic chart describing the relationship between horizontal displacements and the time for each pair of values of elastic and viscous characteristics of the damper for Maxwell and Kelvin – Voigt models. The effect of changes in the values of stiffness and damping parameters on the values of the period and eigenfrequencies of this superstructure was also investigated. Conclusions. The co-authors chose the damper parameters to minimize seismic displacements of the bridge girder and optimally suppress the dynamic interaction between the bridge elements. Viscoelastic elements of the Kelvin – Voigt type provide more regular values of horizontal displacements of the girder when the direction of the seismic effect changes. We also recommend to select the pair of values equal to 20 000 kN/m, 800 kN s/m, and to use the Kelvin – Voigt model in the design of a viscoelastic damper.