Global stability of mono-symmetric I-section high-strength steel beams

This paper presents testing and modelling investigations on the global stability and load-carrying capacities of S460 high-strength steel mono-symmetric welded I-section beams susceptible to lateral-torsional buckling. A testing programme was firstly carried out, including material coupon tests, imperfection measurements and mono-symmetric welded I-section beam tests. Upon completion of the testing programme, a numerical modelling programme was conducted, where finite-element models were developed and validated. The numerical models were then used to perform parametric studies to obtain additional beam data. The obtained test and numerical data were afterwards adopted to conduct a design analysis, where the relevant design rules given in the European, American and Chinese standards were assessed. The assessment results indicated the excessive design conservatism of the European and Chinese codified buckling curves, while the American standard resulted in many unsafe resistance predictions. Finally, an improved design approach was proposed to offer better design accuracy and consistency.