Finite element instability analysis of composite bridge girders

The steel joist of composite bridge girders is susceptible to a particular type of instability which may be referred to as "Restricted-Distortional Buckling". Knowledge of the critical load at which this type of instability occurs is necessary for design. There are different methods available in the literature, with different levels of approximation, but not all produce similar results. This paper will review these methods, and explain their strengths and /or weaknesses. It will also introduce a new technique in detail and present some of the results in a non-dimensional format.