Novel prefabricated joints for underground silos with steel cavity and concrete-filled cavity: Axial compression tests and numerical simulations

In terms of new materials, innovative technologies, and advanced construction techniques, the prefabricated steel plate-concrete composite underground silo offers an effective solution to the key challenges of cost, construction duration, and waterproofing associated with conventional reinforced concrete underground silos. However, joints represent critical weak components in prefabricated structures, and the development of simple and efficient joint configurations is essential for the further advancement and application of novel prefabricated underground silos. To address this issue, two novel prefabricated joints, namely the steel cavity joint and the concrete-filled cavity joint, are proposed, and their axial compressive performance is investigated. First, full-scale axial compression tests are conducted to evaluate the load-bearing, deformation, yielding, and failure behavior of specimens incorporating different joint configurations. Subsequently, nonlinear finite element analysis of both specimens is performed using ABAQUS to further elucidate their load-transfer mechanisms. Furthermore, the effects of key joint parameters on the axial compressive performance are discussed. The results show that the specimen with a steel cavity joint primarily fails due to the instability of external waterproof steel plate under axial compression, with the steel plate contributing approximately 41% of the applied load during the elastic stage. In contrast, the specimen with a concrete-filled cavity exhibits crushing failure of prefabricated concrete blocks, with the cavity concrete contributing approximately 75% of the applied load during the elastic stage. Compared with the steel cavity joint, the concrete-filled cavity joint exhibits significantly improved initial stiffness and achieves an increase of more than 28% in peak load capacity. Moreover, the concrete strength grade in the cavity can be appropriately reduced to optimize material utilization efficiency.