ABSTRACT
To study the flexural performance of high strength steel-UHPFRC composite girders, flexural tests, numerical simulation, and theoretical analysis were comparatively carried out on high strength steel-UHPFRC composite girders and high strength steel concrete composite girders. The failure mode, flexural stiffness, ultimate capacity and corresponded deformation were compared and analyzed. The finite element models with multi-scaled of high strength steel-UHPFRC composite girders were established, and the parameter analysis was carried out. The simplified calculation method applicable to the flexural capacity of high strength steel-UHPFRC composite girders was proposed. The results show that the flexural behavior of the flange of high strength steel-UHPFRC composite girders is significantly improved, and the number of cracks is significantly reduced with smaller widths. Compared with high strength steel concrete composite girders, the flexural stiffness and yield load of high strength steel-UHPFRC composite girders in the elastic stage are increased by 17.4% and 7.1%, respectively. The cracking load in the elastic-plastic stage is increased by 10.2%, and the flexural capacity and ductility in the ultimate state are increased by 10.8% and 26.8%, respectively. The variable parameter analysis results show that the yield strength and ductility of the composite girder can be significantly improved by increasing the strength of the UHPFRC.
