Experimental and numerical study on member classification of I-section plate girders

Section classification is adopted by modern design codes and standards as a basic step in design process. Web-flange interaction is a significant feature that influence cross-sectional behavior but generally not included herein. Moreover, the overall member stability is also not considered during the classification procedure, which is an influential parameter in ultimate strength capacity. Besides the lack of considerations on interaction effects, the web resistance to shear buckling has to be investigated as well, especially for fabricated I-section plate girders. Tests of four specimens with high shear ratio are presented and investigated. It is observed that the features of local buckling of the constituent cross-sectional plate elements and the global lateral-torsional mode are closely inter-related. Insufficiencies in existing design methods are highlighted accordingly. The experimentally verified numerical modeling is carried out to conduct the parametric study. A member classification proposal based on normalized strength capacity is handed in for future Chinese steel design codes in a simple and plain form. Interactions between web-flange plate elements and local-global buckling modes are taken into account.