A rational procedure for modelling imperfections in advanced analysis of frames with locally unstable members

• A rational procedure for implementing geometric imperfections into inelastic large displacement analysis is derived.
• A statistical approach that considers the reliability of the structural strength of a selection of tests of thin-walled members and frames is discussed.
• Finite Element Analysis (FEA) was conducted and used to determine the strength as a function of imperfection spectra for 20 storage rack uprights and 56 frame members.
• Practical recommendations for modelling cross-sectional and member imperfections in advanced analysis are provided.

This paper presents a rational procedure for implementing geometric imperfections into inelastic large displacement (“advanced”) analysis. The procedure uses a statistical approach that considers the reliability of the structural strength of a selection of well-documented tests of thin-walled members and frames. The aim of the study is to derive a statistical procedure for implementing imperfections in shell-element based advanced analyses and to determine an appropriate interval of half-wavelengths and number of eigenmodes to incorporate when modelling geometric imperfections. To achieve this, a analysis of strength as a function of imperfection spectra for 20 storage rack uprights and 56 frame members was conducted using finite element analysis (FEA). All FEA models were calibrated against completed experimental results. Based on the results, practical recommendations for modelling cross-sectional and member imperfections in advanced analysis for individual uprights and storage rack frames are provided.