Elevation and refurbishment of 4 lock bridges on the Albert canal in Belgium

Abstract

The Albert Canal is an important waterway that links the region  around Liège and the North East of Belgium to the port of Antwerp. In order to facilitate the adequate shipment of containers via this canal, all bridges need to have a clearance of at least 4 layers of containers (9.10 m). For that matter, a number of bridges have to be rebuilt while others are subject to elevation and refurbishment. Among the latter are the lock bridges of Diepenbeek, Hasselt, Kwaadmechelen and Olen. These bridges are reinforced concrete box girder type structures, constructed over the lower head of the lock with which they form an integrated part. This means that a mere dismantling of the existing bridge and then building the new and higher bridge from scratch was not an option as it would disrupt the stability of the lock walls. The following phased approach proved to be a workable concept: At first, the construction of the new bottom flange at a higher level  within the box girder; subsequently, the removal of the existing bottom flange and the lower part of the girders, and finally, the application of transverse and longitudinal post-tensioning on the new structure in order to sustain the required traffic loads by a bridge deck with a reduced construction height. In this way the lock bridges were elevated by 0.43 m to 0.65 m, depending on the geographic location, without having to build a completely new structure and without compromising the existing lock structure. As the existing structure proved in some parts to be insufficiently strong to cope with the forces imposed by the external longitudinal post-tensioning, the application of externally bonded CFRP reinforcement was necessary. This article focuses on the study as well as on the execution phase of the elevation and refurbishment.