A Novel Triaxial Test System for Concrete under Passive Confinement

Abstract

Abstract Triaxial testing data are essential for developing the general mechanical model for concrete subject to multi-axial stress. Due to the lack of a test system associated with passive confinement, a novel triaxial test system was designed for a 100 mm by 100 mm by 100 mm cube and verified through testing. The system comprises a uniaxial compression testing machine and a biaxial loading apparatus. The main feature of this system is exerting a detectable passive load in two perpendicular directions. The passive load is the load linearly increased with the expansion of the cube in the same direction of the load, such as fiber reinforced polymer (FRP) confinement. Key issues such as the confinement stiffness ratios, friction reduction pad, and deformation data acquisition and correction have been demonstrated in this paper. A group of concrete cubes are designed to be tested in the system and compared with FRP-confined standard cylinders to verify the feasibility of the new test system.