This document provides an overview of the means to determine the buckling resistance of steel plate girders in composite bridges, both during construction (the bare steel stage) and in service (when the deck slab acts as the top flange). 

The document notes that Eurocode 3 gives principles and general application rules but to apply the rules for composite bridges the designer needs to understand how buckling behaviour can be represented both in manual calculation and through finite element analysis.

Suggestions are made for modifications of verification criteria in Eurocode 3 (which do not fully cover the effects experienced in bridges).  Recommendations are summarized and examples of buckling modes found in FE analysis are given.

Finally, the interaction between major axis and minor axis effects during the construction stage of the worked example presented in SCI publication P357 is considered. The lateral bending effects are greatest on the outer girder (which is not the most heavily loaded girder and the effects were thus not considered in detail in P357) and the calculations show how the combined effects can be verified.

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