Mesh‐Independent Strain Method for FE Assessment of Steel Joints

Abstract

Numerical modelling plays a central role in structural engineering, from routine design tasks to advanced research. The reliability of FE results depends on proper model validation for the failure modes considered. However, FE‐based design in steel structures is not yet fully standardized. The forthcoming Eurocode 3 Part 1‐14 (FprEN 1993‐1‐14) introduces standardized rules for ULS and SLS verifications, including a strain‐based resistance criterion (C2). A key challenge is that FE strains are mesh‐dependent and differ from experimental material behaviour, complicating resistance assessments. This paper presents a methodology to extract mesh‐independent peak strains from validated FE models that satisfy global convergence requirements. The approach relies on a weighted strain‐averaging procedure over volumes, surfaces, or lines around points of interest. Its application to a welded steel joint modelled with solid elements demonstrates consistent, mesh‐independent strains, enabling robust verification of C2‐based resistance and supporting reliable FE‐based design in accordance with the new Eurocode provisions.