Design recommendations for patch loading resistance of longitudinally stiffened I-girders

In steel bridge girders, longitudinal stiffening is primarily employed to increase the flexural and shear resistance. International design codes recommend the use of longitudinal stiffeners at one-fifth of the girder depth as the optimum position for flexural resistance, meanwhile experimental and numerical results found in the literature indicate that the optimum position for patch loading resistance is different. A check for patch loading is required for steel bridges erected by incremental launching at construction stage, since bending and shear govern the in-service girders behavior. Therefore to place a longitudinal stiffener only for patch loading may be uneconomical. This paper is aimed at investigating the behavior of longitudinally steel I-girders with a longitudinal stiffener placed at one-fifth of the girder depth subjected to patch loading. Nonlinear finite element analyses are conducted in order to investigate the interaction between geometric parameters influencing the resistance to patch loading. Finally, design recommendations for longitudinally stiffened I-girders are presented.