Elastic critical load of plates and plate girders subjected to patch load

The determination of the elastic critical load (buckling load) is an important element of the assessment of the ultimate load of plate girders according to Eurocode 3 for design of steel structures. An analysis of the critical load of a plate corresponding to the web of an I-girder for different boundary conditions and the critical load of the I-girder itself subjected to patch load is given in the paper. Conclusions regarding their correspondence are given. Also, experimentally determined ultimate loads of I-girders are compared with predictive values according to Eurocode 3 for the models used in this analysis. A modified procedure for the ultimate load determination is proposed by following the Eurocode 3 algorithm and changing only buckling coefficient. In order to improve the ultimate load prediction, it is suggested to calculate the buckling coefficient also as a function of patch load length.