Lateral-torsional buckling of discretely-braced i-girder

This paper presents an analytical solution for lateral-torsional buckling strength and stiffness requirements of I-girders with discrete torsional bracings subjected to non-uniform bending. The critical moment and torsional stiffness requirement are derived by using an energy method for an arbitrary number of bracing points. An equivalent moment factor is introduced to evaluate buckling moments of fully braced I-girders. From the results, it is found that proposed solutions agree well with results of finite element analyses regardless of the number of bracing points, while results for the equivalent continuous brace stiffness concept are not suitable for multiple discrete torsionally-braced beams.