Interaction behaviour of steel I-girders; part II: Longitudinally stiffened girders

• M–V–F interaction behaviour of longitudinally stiffened steel I-girder is investigated.
• Previous design proposals found in the literature are studied and compared.
• Structural behaviour under the combined loading situation is analysed.
• New design interaction equation is proposed for M–V–F interaction behaviour.

During launching of a bridge structure large bending moment, shear and transverse forces can often occur at the same time in the same cross section which can result in governing situations for the design. In case of these structures the interacting stability behaviour should be taken into consideration. Bridge structures have usually longitudinal stiffeners on the web, therefore the determination of the load carrying capacity of girders with longitudinally stiffened webs under the combined loading situation is an important aspect of bridge design. In the current version of EN 1993-1-5 [1] there is no standard design method to take the interaction of these three effects into account and there are a very small number of previous investigations in literature dealing with this topic. The companion paper (Part I) [27] deals with the M–V–F interaction behaviour of girders without longitudinal stiffeners. The current paper focuses on the interaction behaviour of longitudinally stiffened steel I-girders subjected to bending, shear and transverse force (patch loading). Numerical model is developed to investigate the combined effect of these three internal forces on the load carrying capacity. Based on the numerical parametric study design interaction equation is proposed to consider the M–V–F interaction behaviour of girders with longitudinal stiffeners in the design.