Load testing and evaluation of inverted T-section slabs in road bridges

OT-slab road bridges and their capacity were investigated in a comprehensive Danish research project. Such bridges are constructed with prefabricated prestressed overturned T-section beams with in-situ concrete cast on top and are combined with transverse reinforcement for shear load transfer. Often existing bridges suffer from low capacity evaluations insufficient to meet current and future traffic-load requirements. However, recent studies indicate higher capacities than predicted in applied theory. This capacity increase seems to be due to slab behavior rather than strip behavior where insufficient interaction between the OT-elements is presumed. This paper presents evaluations of OT-bridge slabs, based on results from a Danish bridge testing project, (V1), initiated in 2016. The study evaluates capacities in relation to the strip method and yield line theory where Danish standard classification vehicle loads are applied. The results indicate that the strip method may underestimate the capacity of the tested OT-slabs that the yield line theory may be a more suitable assessment method up to the demonstrated load magnitudes.