Experimental investigation of the seismic performance of an L-shaped roof-sidewall joint with a cogging composite connection

Abstract

The prefabricated connections with better mechanical properties and optimal layout are keys to guarantee good seismic and waterproof performances of assembled underground structures. In this study, a local prestressed cogging (high-strength bolt-grouted sleeve) composite connection (HSB-GS), an integral prestressed cogging (prestressed steel strand-grouted sleeve) composite connection (PS-GS), and a non-prestressed cogging (ultra-high performance concrete-grouted sleeve) composite connection (UHPC-GS) are proposed. Subsequently, three 1/4-scale prefabricated roof-sidewall specimens comprising the three proposed connections and an integral cast-in-place specimen were designed and fabricated. Finally, quasi-static tests were conducted on the specimens, and the results were verified through finite element analysis. The experimental and numerical results show that UHPC exhibits excellent bonding performance with ordinary concrete, and it can prevent and delay damage to the seam. Furthermore, cogging can limit crack development and improve the shear resistance of the connections to a certain extent. The HSBs can improve the self-resetting ability of the specimen and delay damage to the seam to some extent. Therefore, when HSB-GS and PS-GS are arranged in the roof plastic hinge and UHPC-GS is arranged in the roof-sidewall joint core, they can lead to the transfer of the roof plastic hinge. In addition, the HSB-GS and PS-GS arranged in the roof plastic hinge can easily cause shear damage to the joint core; while the UHPC-GS arranged in the joint core can decrease the relevant damage to the joint core.