Behavior of underwater concrete columns confined by non-dispersive mortar and stainless steel tube subjected to core axial compression

Abstract

Bridge pier columns are prone to steel corrosion and peeling of the concrete cover of the concrete in long-term service in the underwater environment. There is currently no better solution for improving the bearing capacity of bridge piers in underwater environments. To solve the problem, a novel reinforcement method was proposed for underwater bridge piers without cofferdams, which uses the stainless steel tube (SST) as an external template and fills the non-dispersed mortar (NDM) between the bridge piers and the SST. A total of 16 SST and NDM confined concrete tubular columns were prepared. Experiments were conducted to investigate the effect of confinement of the SST under axial load only on the core section to simulate the actual situation of underwater piers. The effects of the thickness of the SST and the types of NDM on the compressive performance of the core were compared. The test results indicate that the bearing capacity of the reinforced specimen can be increased by more than 2.5 times that of the original pier column. The thickness of the SST is the main parameter that affects the stress-strain curve. Compared to joint loading, core section loading can increase maximum stress by more than 10 %. A multiscale analysis was conducted on the model of steel tube confined concrete (STCC) columns. A method was proposed to calculate the bearing capacity of reinforced columns. The research results can provide a new method and theoretical basis for the reinforcement technology of underwater bridge piers.