The subject discussed in this paper is based on an experimental bridge model which was built to study the pre-critical and post-critical buckling behaviour of steel webs of box girders provided with longitudinal and transversal stiffeners. The article presents a comparison between the experimental results and the numerical ones for buckling resistance of stiffened steel webs. For this purpose two types of analysis will be carried out: an analysis to establish the values and eigenvectors of buckling, after which the critical factor for the first mode of buckling will be obtained, and then a geometrical and physical nonlinear analysis will be performed.