Keywords: dynamic simulation, railway bridge, finite element method, model updating, monitoring, vehicle-bridge interaction.

Dynamic simulations are necessary to predict the behaviour of bridges loaded by high-speed trains. These simulations are expensive, require a lot of computational power and are very sensitive to input parameters that are difficult to estimate. This papers studies the viability of a number of simplifications for the modelling of complex bridges and the trade off between accuracy and computational cost, in which these simplifications result. This could be an important advantage against more complex and demanding models, especially in the early stages of development. In this work the dynamic behaviour of a multi-span, continuous beam, prestressed, concrete bridge is simulated with the aid of a simplified two-dimensional finite element model. The bridge in question is the New Årsta Bridge that connects the city of Stockholm with the southern suburbs over the Årsta Bay. It was chosen because of its complexity and because of the amount of validation data available. The bridge complex geometry and mechanics will require a very large model to completely account for them. Also, the extensive studies realized on the structure in the past, as well as the comprehensive monitoring system installed on the structure, allowed for valuable validation material. These studies include a more complex, three-dimensional finite element model of the bridge, as well as several measurements under controlled loading, both dynamical and static, plus the continuous data on accelerations and strains obtained from the monitoring system. The bridge is modelled with beam elements and the vehicles acting on it are modelled as moving point loads. The results obtained are compared with those obtained by other more complex three-dimensional models as well as with the actual response of the bridge measured in situ by a long term monitoring system. Furthermore, based on the measured dynamic behaviour of the structure, some model parameters are updated to obtain a better accuracy. The feasibility of obtaining a good approximation to the dynamic parameters of the structure without parameter updating is also discussed. The main aim of this study is to check the validity of simplified models and simplified analysis of the response of complex bridges to moving trains, as well as the capabilities of updating and enhancing the model accuracy.

purchase the full-text of this paper (price £20)

go to the previous paper
go to the next paper
return to the table of contents
return to the book description
purchase this book (price £145 +P&P)