Collapse test of the Vecht Bridge: behaviour of post-tensioned concrete slab-between-girder bridges

In the Netherlands, approximately 70 prestressed slab-between-girder bridges are present, built between the 1950s and 1970s. These bridges typically do not fulfil the requirements for shear in an assessment, but show no signs of distress upon inspection. Additional load-carrying mechanisms and effects of global bridge behaviour, such as compressive membrane action, compressive arch action, load (re)distribution, and the influence of the crossbeams, which could significantly enhance the structural capacity, are typically not considered in the assessment calculations. This paper studies the global structural behaviour experimentally of the full slab-between-girder bridge system as compared to the isolated T-girder. For this purpose, two spans of an existing multi-span T-girder bridge, the Vecht Bridge, built in 1962 were tested. In total, three experiments were carried out in span 4 (full system), and four experiments in span 2 (after applying saw cuts in the deck to create isolated girders). This paper reviews the state-of-the-art regarding collapse testing, global bridge behaviour, and slab-between-girder bridges in the Netherlands. Then, the results of the experiments are presented and analysed. It is expected that these experimental results will form the basis of improved assessment methods for slab-between-girder bridges in the Netherlands and beyond.