Redesign of bridges Twentekanaal in Ultra-High Performance Concrete

Abstract

Within the Dutch infrastructure there is the challenge of having to replace or strengthen a large number of existing structures within the upcoming years. This challenge also provides the opportunity to develop new concepts. The promising concept described in this report involves the application of UHPC to redesign the decks of existing concrete bridges in combination with the reuse of existing foundations. The Twentekanaal was selected as the topic of the project, because it comprises many bridges of which various have similar characteristics and were built in the same period. Not all bridges could be considered in-depth simultaneously. Therefore, one representative bridge was selected, the Eefdesebrug, after which the results for this bridge would be generalised onto all other relevant bridges across the canal. To determine the full potential of the project, it was investigated up to what extent the results for the Eefdesebrug could be projected onto other bridges across the canal. An inventory was set up containing all bridges. These were characterised and compared based on bridge category, year of construction and dimensions. This resulted in a total of twelve bridges with similar characteristics, to which the results of the redesign of the Eefdesebrug could potentially be generalised to. After the potential of the project had been determined, the focus was placed on the redesign of the Eefdesebrug, which was carried out following a stepwise approach. After each design phase, the global goal of the project was reflected by means of a weight comparison with the existing bridge. To limit the scope of the project, the new deck should be constructed using prefabricated beams. The design would be based on the Eurocode, supplemented by the AFGC-SETRA 2013 guideline. The final design resulted in a 32% reduction of the self-weight compared to the existing bridge. This design comprises pretensioned box beams with a slenderness of 36. A global assessment of the existing foundation was subsequently carried out. A criterion for reuse of the existing foundation was formulated based on the vertical loads due to permanent and vertical variable actions in the new and existing situation. This criterion was satisfied, with which the possibility of reuse of the foundation of the Eefdesebrug had been demonstrated. It was subsequently investigated what may be expected if the solution for the Eefdesebrug would be applied onto the group of twelve aforementioned bridges. Using the results for the Eefdesebrug it was possible to estimate the dimensions for the other bridges and to consider the vertical forces acting upon the foundations. It was shown that a similar solution can be applied to all twelve bridges across the Twentekanaal with characteristics similar to those of the Eefdesebrug.