Shear capacity of slabs under a combination of loads

Existing solid slab bridges under a combination of wheel loads and distributed traffic loads sometimes do not fulfil the code requirements for shear. However, reinforced concrete slabs loaded close to the support are subjected to shear stresses which might result in a failure mode of combined punching and shear. This behaviour is studied in a first series of experiments on slabs under a concentrated load close to the support, and these experiments resulted in a set of recomrendations. To verify if these recommendations can be used when assessing solid slab bridges under distributed and concentrated loads, slabs under a combination of a line load, representing the dead weight, and a concentrated load, representing a wheel load, are tested up to failure. The experimental results are used to assess the ultimate shear which can be carried at the support and the influence of the varied parameters is discussed. The results demonstrate how different types of loading such as dead loads and live loads can be superposed and how a stress check at the support can be carried out.