NONLINEAR ANALYSIS OF LOCALLY BUCKLED I-SECTION STEEL BEAM-COLUMNS

摘要

The paper describes the development of an advanced finite element analysis of thin-walled high strength steel I-sections in combined compression and major axis bending. The analysis accounts for geometric and material nonlinearity, and incorporates measured values of geometric imperfections and residual stresses. The failure modes involve local buckling of component plates, in-plane bending and out-of-plane flexural-torsional member buckling. The finite element analysis is shown to be in good agreement with tests. A study is included to devise a simple method for measuring and modeling geometric imperfections in advanced analysis. It is shown that the accuracy achieved by determining the amplitude of the local geometric imperfection from a small number of mid-length measurements is comparable to that obtained by modeling the complete measured geometric imperfection consisting of measurements along the full length of the member at several points in the cross-section. A further study is included to investigate the sensitivity of the finite element analysis to changes in local geometric imperfection.