Dynamic behaviour of a composite twin girder bridge in a high speed interoperable line

A high-speed railway system is presently under implementation in Portugal, which will allow the connection of the country with a large European network.

At the moment, many countries have already developed their own structural solutions for dealing with the effects of high-speed trains in bridges and a great number of structures have been in operation for several years. These solutions were initially designed for specific train types, thus being checked for the dynamic effects of only a small part of the actual European high speed rail traffic.

Recent advances in the understanding of the behaviour of high speed railway bridges have been introduced in the EN 1990-Annex A2 and EN 1991-2, reflecting the work undertaken by the ERRI committee D214. In the case of interoperable lines where the high speed TSI is applicable, this being the case of the future Portuguese high speed network, additional checks for dynamic analysis using High Speed Load Model should be performed.

One of the solutions that has proven to be very competitive in France is the composite twin girder bridge. This type of deck is used in continuous schemes, with spans lengths ranging from 40m up to 65m.

In this paper the dynamic behaviour of this type of bridge is assessed using as reference a 333m long composite twin girder deck located on the French TGV Nord line. The bridge is continuous over its entire length, comprising 7 intermediate spans of 40m and 2 end spans of 28m and 25m. Dynamic analyses of the bridge were performed for both the European high speed trains and the HSLM load schemes, using various types of FE models of increasing level of detail. The response of the bridge is checked in terms of structural safety (amplification levels and fatigue requirements), deck acceleration and passenger comfort.