Modelling of local elastic buckling for steel beams with web openings

摘要

This work is mainly concerned with the development of sophisticated yet efficient methods forudassessing the elastic buckling of steel beams with web openings, focussing on local buckling effects inudthe web region. A new computational method is proposed which extends the use of the Element FreeudGalerkin (EFG) method for the numerical discretisation combined with a simplified bucklingudassessment approach based on the Rotational Spring Analogy (RSA). The new approach considersudseveral potential simplifications offering a balance between computational efficiency and accuracy inudlocal buckling analysis.udIn the present EFG/RSA method, considerable advantage is established by separating theudplanar and out-of-plane responses. Planar analysis is further enhanced using modular concepts, whereudthe beam is divided into unit cells, each of which resembles a super-element with a reduced number ofudfreedoms, and solved using a standard discrete procedure. As for the out-of-plane analysis, theudapplication of a ‘local region’ is adopted to significantly reduce the size of the original bucklingudproblem. Finally, local buckling assessment is conducted using an effective approach that utilises anuditerative procedure based on a rank 2 reduced eigenvalue problem along with a shifting local region.udSeveral illustrative examples are provided which highlight the efficiency and accuracy of theuddeveloped approach in comparison with detailed nonlinear finite element analysis performed usingudADAPTIC, and which demonstrate general applicability to local buckling analysis of steel beams withudweb openings of various shapes and sizes.udThis work also considers the development of a simplified design-oriented method which isudpresented particularly for web-post buckling. Towards this end, a simplified analytical model isudproposed based on an analogy with equivalent rectangular thin beams (RTB), where a semi-empiricaludapproach is used to calibrate the suggested formulation against the results obtained from the numericaludwork performed earlier.