Journals Proceedings

Abstract

A number of recent monitoring project of steel box girders in Belgium have indicated that daily temperature variations can be an important load condition. The resulting behavior is not always included in the design loads according to the codes. As part of a large-scale project in order to improve the accessibility of the Belgian capital by train, the existing railway line between Brussels and Ghent is expanded from 2 to 4 tracks over a length of 25 km. This line crosses the valley of the river Pede by a 523 m long historic viaduct, built in the 1930‟s. In those days the viaduct was chosen over large backfills in the valley due to poor soil conditions. With respect to the protected work of art, two additional lateral fly-overs consisting of steel box girders with variable hollow section are integrated in the existing viaduct. This paper shows the results of the detailed monitoring program verifying the design and behavior of the newly built superstructure. Extensive strain measurements were performed during a two-day load test, together with acceleration measurements in order to evaluate the dynamic response of the structure. In addition long term strain monitoring was carried out in order to study the effects of temperature gradients on the closed steel box girders of the fly-overs. The measured temperatures are introduced into a finite element model. Stresses resulting from this model are compared with measured stresses and stresses based on calculation using the same model but based on Eurocode load combinations. While the size of temperature variations is more or less as was expected the resulting behavior is more complex and less homogeneous than is generally assumed