Section moment capacity tests of hollow flange steel plate girders

Hollow flange steel plate girder (HFSPG) is a new hollow flange I-section made using cold-formed rectangular hollow sections (RHS) as flanges and a steel plate as web. Due to the increased torsional rigidity and unique geometry, it can provide enhanced flexural capacities and thus are effective flexural members in long span applications. The production of proposed HFSPGs contains welding currently available RHS sections to a web plate, which allows engineers to form girders by varying dimensions, thicknesses and grades to suit their design requirements. As the first step of this study, the section moment capacities of fully laterally restrained HFSPGs were investigated. Despite earlier researches on the flexural capacities of hollow flange sections, HFSPGs have not been tested previously. Therefore, twelve section moment capacity tests were conducted to study the flexural performance and capacities of HFSPGs. The ratios of ultimate moment capacity per unit area of tested beams were compared with conventionally used hot-rolled I-sections with similar cross-sectional area, which proved the structural efficiency of HFSPGs over commonly used hot-rolled I-sections. The ultimate capacities of tested HFSPGs were then compared with capacity predictions provided by the Australian, American and European design standards (both hot-rolled and cold-formed). It was found that the current design standards under-estimate the section moment capacities of HFSPGs in general and the level of under-estimation varied depending on the section slenderness. Suitable recommendations are made regarding the appropriate use of these design standards for HFSPGs. This paper presents the details of this research and its findings.