Study on shear capacity and slip behavior of grooved rivets based on push-out tests

Shear connectors are critical components governing the shear transfer efficiency and long-term service reliability of composite structures. Conventional headed stud connectors require extensive cast-in-place operations and involve long construction cycles. In contrast, ordinary bolted connectors are susceptible to preload relaxation under complex conditions, such as high altitudes and low temperatures. To address these limitations, this paper proposes a novel shear connection method using ring-groove rivets (RGRs) for application in hybrid wind turbine towers. To evaluate the shear performance of RGR connectors, experimental studies on 18 push-out specimens were conducted. The failure mode, characterized by shear fracture of the rivet shank, and the corresponding interface shear-slip curves were analyzed, revealing good consistency across specimens. Furthermore, the effects of rivet diameter, strength grade, embedment depth, and longitudinal spacing were systematically investigated. The results indicate that rivet diameter and material strength are the primary factors governing the ultimate shear capacity, while a double-row arrangement significantly improves both interface stiffness and ductility. Based on the experimental results and the high preload characteristics of RGRs, it is shown that existing design codes tend to underestimate their shear capacity. Consequently, an improved theoretical model for calculating shear bearing capacity, incorporating a preload parameter, was proposed. The proposed model was verified against the test results, showing good agreement with prediction error within 10%.