Abstract：In order to determine the weight limits of simply supported RC short-and medium-span highway bridges, a simplified analytical
method, which is applicable to different design load classes or attenuations of resistance, was proposed. Firstly, by introducing the
correction factor of resistance, the limit state function of flexural failure of RC beams was established. Secondly, according to the
probability density functions for flexural resistance and dead load effects of RC highway bridges suggested in the code, a simplified
analytical model for determining the weight limits of highway bridge with correction factor considered was proposed. Furthermore, based
on the resistance level as specified in 2004 edition of the code, the coefficients of weight limits corresponding to different
correction factors of resistances were computed with the ratios of live load to dead load adopted in bridge design taken as the
fundamental parameters. Finally, with the 13m RC box beam taken as an example, the feasibility of the simplified analytical model was
verified, and the modification method of weight limits was also proposed through analyzing the coefficients of weight limits and the
weight limits of typical trucks. The results show that a certain safety reservation can be achieved if the proposed model is employed to
calculate the weight limit values, indicating that it can be used for determining the weight limits of highway bridges at different
resistance levels.
