Experimental investigation on static mechanical performance of grouped-stud shear connectors in steel–UHPC composite beams

Abstract

The static mechanical properties of grouped-stud shear connectors in steel–ultra-high-performance concrete (UHPC) composite beams are rarely investigated. In this study, the static mechanical properties of grouped-stud shear connectors in steel–UHPC composite beams are investigated via experiments and numerical simulations. Seven sets (14 specimens) of push-out tests are conducted by varying the parameters, including the concrete type, stud diameter, stud vertical spacing, and number of stud rows. The test results show that the shear bearing capacity of grouped-stud shear connectors increases by 27.5% as the stud diameter increases from 19 to 22 mm, by 13.2% compared with that of grouped-stud shear connectors in steel–UHPC and steel–normal concrete (NC), and by 5.8% when the stud vertical spacing increases from 125 mm (5.68d) to 200 mm (9.09d). However, the shear bearing capacity of the grouped-stud shear connectors remain almost unchanged when the number of stud rows is changed from two to four. The effects of stud diameter, stud tensile strength, stud vertical spacing, stud length, the cover thickness of the stud head, and stud transverse spacing on the shear bearing capacity of the grouped-stud shear connectors are investigated via numerical simulations. The results show that the stud diameter, stud tensile strength, and stud vertical spacing significantly affect the shear bearing capacity of the grouped-stud shear connectors, whereas the stud length, the cover thickness of the stud head, and stud transverse spacing exert almost no effect. Based on experimental and numerical analyses, an equation for predicting the shear bearing capacity of grouped-stud shear connectors in steel–UHPC is proposed and validated based on experimental and numerical results.