Model factor calibration for FEM-based design of slender steel welded plated structures

Abstract

FEM-based design is getting widely used in the daily design practice of steel structures. A new Eurocode standard – prEN 1993-1-14 is under preparation to regulate its application. The direct resistance check, where numerical model determines the resistance of the structure needs improvement in terms of handling the uncertainties and ensuring the required safety. The FEM-based design should take into account all the uncertainties handled in traditional analytical calculations and the uncertainties of the numerical model, thus ensuring an equivalent level of safety as required by the Eurocode standards. Therefore, the value of the partial factor associated with the uncertainty of the calculation model should be reassessed and the uncertainty and reliability of the numerical models should be examined. A methodology to evaluate the uncertainties on the resistance side is developed and summarized in this paper, which proposes partial safety factors (γ_Rd, γ_m, γ_M and γ_FE) adapted to the failure probability objectives of the EN 1990 standard. The focus of the study is on a specific failure mode - bending resistance of steel box-section beams - using the results of laboratory experiments. The current paper presents the calculation of the model factor (γ_FE) for this specific failure mode by using a shell-type numerical model and also compares its application to Monte Carlo simulation-based reliability analysis results to prove the appropriate safety.