The influence of transversal bending moment on reduction of resistance I-girders with corrugated webs is investigated. This moment is caused by the longitudinal shear flow between flange and corrugated web. The moment MZ is not defined in Eurocode EN 1993-1-5, neither EN 1999-1-1. Both codes of standards give different concepts of resistance verification because of different authors. Both of them encourage acceptance of transversal moment in case of trapezoidal corrugation.In numerical example a steel I-girder with span L=18 m, with height of corrugation a3=0.08 m and web thickness tw=0.0025 m loaded by two transverse forces with value F=500 kN is investigated. For the clarification, different concepts of accounting girder resistance and different formulas for transversal moment are compared.