The loads that are used for the assessment of existing reinforced concrete slab bridges are the self-weight, superimposed loads, and distributed and concentrated live loads. As such, the shear capacity of reinforced concrete slabs under a combination of distributed and concentrated live loads is a topic of practical relevance. For slabs subjected to a single concentrated load, a plastic model for assessment exists: the Extended Strip Model, developed based on the Strip Model for concentric punching shear. A further adaptation of the model to assess slabs subjected to distributed and concentrated loads is presented in this paper. The proposed model is compared to experiments on slabs subjected to a single concentrated load and a line load. The conclusion of this comparison is that the Extended Strip Model results in a safe estimate of the maximum concentrated load on the slab, and that the method can be used for the assessment of existing bridges subjected to heavy truck loads.