Device for applying axial pressure to steel pipe-confined concrete specimen and working method thereof

The invention relates to a device for applying axial pressure to a steel pipe-confined concrete specimen. The device comprises a steel pipe and core concrete, wherein the core concrete is cast into the steel pipe; both ends of the steel pipe are respectively reserved with a groove without core concrete; a loading head is arranged in each groove at both ends of the steel pipe; one end of each loading head is inserted into the corresponding groove and is in contact with the end surface of the core concrete, and a loading cap is arranged at the other end of each loading head; a plurality of one-way strain sheets are wound at the side surface of each loading head at equal distance along the circumference direction. The invention also relates to a working method of the device for applying axialpressure to the steel pipe-confined concrete specimen. The device has the advantages that the numbers produced by the strain sheets can be directly observed and compared so as to more accurately judge whether the concrete is