Demolishment of a post-tensioned concrete viaduct across a motorway in Almere, The Netherlands

摘要

In Western Europe there are many concrete bridges and viaducts which were built 35 years orrnmore ago. Although most of these concrete structures can be maintained, some structuresrnbecome functionally obsolete. Because of the strongly increased traffic between Amsterdam andrnAlmere, the Motorway A1 and A6 will be widened in the next years. Overpass “Havendreef” spansrnmotorway A6 and is one of the structures which need to be replaced in order to realise the widerrnmotorway underneath. This two span viaduct consists of a post-tensioned concrete slab with arnvarying construction depth.rnMany difficulties were encountered in this project from an engineering point of view. How to dealrnwith a lack of structural information? What is the structural behaviour of the post-tensionedrncables after cutting? Which part could structurally be demolished in the first phase and which inrnthe second?rnBecause the penalties for traffic hindrance due to construction are strict, the overpass had to berndemolished as fast as possible, whilst underneath one span the traffic flow was undisturbed.