Abstract
High-speed transport infrastructure such as the Shinkansen mil line in Japan or superhighways involve the construction of very long elevated bridges, and seismic analyses of such semi-infinite structures are typically performed by considering a unit of the structure with free boundary at each end. However, the end of the unit is not free in practice, and interaction with adjoining structures is inevitable. Furthermore, a simple wave solution that can be applied to the soil structure is not applicable to the structure of a discrete system such as an elevated bridge, which consists of columns, beams and joints. The present authors have formulated the energy transmitting boundary as an infinite continuous system using the mass-spring model or a beam element model. However, the energy transmitting boundary is for analysis in frequency domain, and then it is not applicable to nonlinear analysis. In this research, for applying to the analysis in time domain, a viscous boundary is introduced using the mass-spring model for a discrete system with an infinite medium. And an equivalent viscous boundary is proposed for frame structure using a two-dimensional beam element.
