Influence of reality‐based imperfections on buckling behavior of steel bridge web panels under bending and shear stress

Abstract

To extend the service life of existing steel bridges, assessments using state‐of‐the‐art design models that account for actual conditions have become increasingly important. This is particularly critical when actual imperfections in existing members exceed manufacturing tolerances, making it challenging to draw direct conclusions from computations. In this paper, the influence of measured out‐of‐plumb imperfections of slender bridge web panels under bending and shear stresses is investigated and compared with the panels' structural performance under typical design imperfection modes specified in EN 1993‐1‐5 [1], such as the half‐sine wave and the first eigenmode. First, measurement data from 3D scans of large‐scale tests are collected and evaluated. Subsequently, a finite element model is developed to study the nonlinear buckling behavior of web panels across a range of slenderness ratios typical of bridge construction. The use of measured imperfections significantly increases the load‐bearing capacity of stocky panels but can also reduce the resistance of slender webs compared to the first buckling mode. Hence, applying the first buckling mode is not always a reliable approach for determining the lower limit of the structural performance of web panels in existing steel bridges.