Concrete axis stretching creep tester and test method thereof

The invention discloses a concrete axis stretching creep tester and a test method thereof. The tester comprises an upper pulling plate, a lower pulling plate, pulling bars, screws, a spring, a stress sensor and vibrating string extensometers, the pulling bars are fixed on the lower pulling plate, and the upper ends of the pulling bars are provided with thread ends; the upper pulling plate traverses the upper ends of the pulling bars and is sleeved on the thread ends, and the thread ends at the upper and lower sides of the upper pulling plate are provided with nuts to fix the upper pulling plate; the upper and lower pulling plates are provided with the screws respectively and are used for the fixed connection of the upper and lower end of a concrete test piece, and the vibrating string extensometers are arranged at two sides of the concrete test piece; and the screw on the upper pulling plate stretches out of the upper pulling plate, the spring is sleeved on the stretching end of the screw, the stretching screw is also sequentially sleeved with a pad and a nut, and the stress sensor is arranged between the pad and the nut. The tester and the method realize the continuous automatic detection and acquisition of deformation; and no eccentricity, concentrated stress and constant stress are realized in the stretching process, so the test accuracy is improved.