Abstract
This paper investigates the load-carrying capacity of existing railway box-girder bridges through a comprehensive analytical approach. The reduced stress method is utilized, which determines stress limits for stiffened and unstiffened plates under combined loading conditions. This method offers an alternative to the traditional effective width approach used for plated structural elements. The paper presents three case studies, demonstrating the integration of global analysis using 2D finite element models, linear buckling analysis of plate/shell structure, and the verification of planar elements via the reduced stress method. The proposed procedure enables more realistic estimations of the load capacity of planar elements by accounting for the complex stress distributions within the panels, thereby enhancing the accuracy of structural assessments, especially details.