Flexural behaviour of longitudinal segment joints with quick C–T type connectors and their corrosion characteristics

Abstract

To address the challenges of slow construction and low assembly precision associated with traditional bolted joints, a novel type of longitudinal joint connected by quick C–T type connectors (C–T joints) has emerged. While this new joint design offers improved flexural behaviour, the connectors are more sensitive to corrosion. Thus, this paper comprehensively investigated the mechanical properties of C–T joints, and the effects of corrosion were also highlighted. First, a series of full-scale experiments and fine numerical simulations are performed to elucidate the flexural behaviour and failure pattern of C–T joints. A numerical simulation method for corroded connectors is then proposed based on corrosion experiments with C/T connectors and is used to explore the corrosion effect on the mechanical properties of C–T joints. The flexural process of the C–T joint can be divided into four stages. The first three stages are the initial high-stiffness, free deformation after the axial force is balanced, and increased stiffness upon connector contact. During the regular tunnel operation stage, the joint remains in the initial two stages. The fourth stage behaves differently under positive and negative moments because of structural disparities between the intrados and extrados. Positive moments result in connector fracture, whereas the compression zone of concrete collapse occurs under negative moments. In both scenarios, cracks emerge and extend outwards from the connectors on the joint plane, meaning that the anchoring of C–T connectors is a key design point. Corrosion has little influence on the mechanical properties of joints before the connectors contact, but it prolongs the second stage, shortens the third stage, and causes a rapid decrease in the ultimate bearing capacity of the joint. When corrosion is more severe, the bearing capacity of the joint remains consistently low.