Strain Limit in Structural Steel Joint Analysis

Abstract

Inelastic numerical analysis is a classic method in engineering practice. Failure criteria are primarily expressed in terms of plastic strain limits. Several factors influence the plastic strain limit, including material properties, element geometry, numerical element type, mesh density, and constitutive relations. Component-Based Finite Element Method (CBFEM) is a widely used technique for the design of steel connections. It combines the analytical component method with the numerical finite element method (FEM). FEM is used to determine the distribution of internal forces, and plates are modeled using 4-node shell elements. Con-nection components are replaced by dependent nonlinear springs and analysis models derived from their specific behavior. This paper presents the results of determining the plastic strain limit for CBFEM numerical calculations. The limit is presented as a reduced value of the ultimate strain. The partial safety factor was determined for nine geometries of weakened plates based on design values obtained from Monte Carlo simulation and reliability analysis. The Monte Carlo simulation was performed using a combination of FEM analysis and analytical formulas implemented in Python. The plastic strain limit was found to be 4.77% over all mesh densities.