Hybrid Nonlinear Seismic Analysis of Bridges with Moving Traffic

Abstract

Owing to current limitations on seismic forecasting, there is a high chance that a considerable number of vehicles will remain on bridges when an earthquake occurs. In traditional seismic analyses, traffic loads were often ignored. Mode-based bridge–traffic interaction analysis usually cannot consider the nonlinearity effects of bridges under earthquakes, which are critical to short- and medium-span bridges. Traditional nonlinear seismic analyses using commercial or open-source software cannot directly incorporate complex dynamic interactions between moving vehicles and bridges. There is no reported methodology so far that can be used for nonlinear seismic analyses of typical short- and medium-span bridges while rationally considering the coupling effects between the bridge, moving vehicles, and an earthquake at the same time. A hybrid simulation approach is proposed to conduct nonlinear seismic analyses of bridge–traffic–earthquake systems by integrating stochastic traffic flow simulation, a mode-based fully coupled simulation technique of bridge–traffic systems, and a nonlinear seismic analysis platform developed based on OpenSees. A skewed and curved bridge, which is a design commonly used to overcome complex intersections and terrain restrictions for short- and medium-span bridges, is studied as a demonstration followed by the numerical investigation of the bridge’s seismic performance and the impact of incorporating traffic loads. The results suggest that the proposed hybrid methodology can capture complex dynamic interactions between bridges and multiple vehicles as well as nonlinear seismic performance to provide rational prediction results.