Early Applications of Prestressing to Bridges and Footbridges in Brussels Area

This paper traces the origin of three very early applications of prestressing by post-tensioning on bridges and footbridges built in the Brussels area 1942-1947. The proponent of prestressed concrete in Belgium was Professor Gustave Magnel from Ghent University who was well aware of the developments in prestressed concrete in France and in Germany. In 1941, he set up the project of building what would eventually be the 1st pretressed railway bridge in the world. It consisted of simple slabs with 20 m span. It was built in Brussels 1942- 1944 on the North-South Railway Junction. For this application, Magnel developed with the contractor Blaton- Aubert a very successful system of prestressing cables and anchorages. This first realization of a prestressed concrete structure in Belgium was accompanied by an extensive testing program that included the on-site testing up to failure of a prestressed concrete beam with the same span and depth as the bridge deck. This experiment convinced rapidly the Corps of Civil Engineers of the Ministry of Public Works to accept considering bids to reconstruct bridges in prestressed concrete rather than in reinforced concrete. Early in 1944, several contracts for reconstructing bridges or footbridges in prestressed concrete had been awarded. The paper details two of these projects, which are footbridges, situated in the Brussels area. The first one, in Brussels, is a footbridge with 21 m span. It was opened to service before September 1944. The second one is a footbridge with 44 m span situated 15 km SW of Brussels. Its innovating feature was the application of external prestressing with high strength steel bars. It was opened to service in October 1947.