Shear performance of prestressed composite box beams with ultra-high-performance concrete and corrugated steel webs under different loading conditions

Composite box beams with concrete flanges and corrugated steel webs (CSWs) have been widely adopted in bridge engineering owing to their light weight and ability to prevent web cracking. By replacing conventional concrete flanges with those made of ultra-high-performance concrete (UHPC), a novel non-prismatic prestressed CSW-UHPC composite box beam was designed and proposed in this study to achieve lighter weight, longer span, and more rapid construction for highway bridges. Owing to differences in geometric dimensions and material properties, the shear states in the proposed novel prestressed CSW-UHPC composite box beam may differ from those of conventional beams. In this study, a formula for calculating the shear stress in a non-prismatic beam with CSWs was derived, and a simplified formula was suggested. Additionally, a large-scale non-prismatic prestressed CSW-UHPC composite box beam was designed and tested to investigate the typical shear stress distributions during different construction stages. To simulate the states during construction, six loading conditions were considered by varying the loading positions and boundary conditions. The shear stress distributions along the depth and longitudinal direction of the specimen were obtained and agreed well with the results obtained from the simplified formula and finite element model (FEM). As the inclined bottom flanges contributed a considerable proportion to the shear resistance, the shear bearing ratio of the CSWs varied under different loading conditions, which correlated with the combined effect of internal forces. The effective shear force or shear bearing ratio of the CSWs varied depending on the consistency of the shear force directions. Finally, several design considerations were proposed for the design of novel non-prismatic prestressed CSW-UHPC composite box beams.