Innovative dual-steel-shell concrete (DSSC) straddle-type track beams design: Shear-tension behavior of studs

Traditionally, straddle-type track beams require considerable depth to accommodate stabilizing wheels of monorail, resulting in greater self-weight and adverse visual impact. To address these shortcomings, this paper proposed dual-steel-shell concrete (DSSC) straddle-type track beams with the inverted-T shaped section, which eliminates stabilizing wheels and symmetrically arranges the running wheels to ensure lateral stability of the monorail. In this innovative configuration, studs must simultaneously resist interfacial shear slip and separation forces (e.g., steel buckling mitigation). The push-out tests and finite element (FE) analyses were conducted on the specimens with 16 mm diameter stud. The results demonstrated that tension induced a degradation in shear capacity and stiffness of studs. When subjected to 60% of the tensile capacity, the shear capacity and stiffness of tension-shear specimens decreased by 23.78% and 21.96% compared with the pure shear specimens. For strength of concrete exceeding C50, the shear capacity remained essentially constant. The developed theoretical formula integrating stud bending angle and effective deformation length demonstrated excellent agreement with experimental and FE results. These findings establish reliable design criteria for DSSC structures.