Static and dynamic bonding-slipping whole-process curve testing apparatus and testing method thereof

Abstract

The invention relates to the technical field of the experimental study and in particular relates to a device and a method for testing bonding-slipping of a reinforced bar material and concrete in a reinforced bar pulling-out process. A static and dynamic bonding-slipping whole-process curve testing apparatus comprises a hydraulic servo testing machine, a test-piece drawing frame, an LVDT fixing protective clamp and a spherical hinge, wherein the hydraulic servo testing machine is connected with the test-piece drawing frame by the spherical hinge, the test-piece drawing frame is used for fixing a test piece, and the LVDT fixing protective clamp is arranged at the free end of the reinforced bar of the test piece. The static and dynamic bonding-slipping whole-process curve testing apparatus is simple, can be utilized repeatedly, and can be operated conveniently; the whole loading scheme comprises two stages, in the first stage, an LVDT is used as a control signal and can be used for eliminating influences of all link intervals and self-deformation of the testing apparatus; in the second stage, the displacement is used as a control signal and can be used for avoiding the influence of the rigidity change in a reinforced bar pulling-out process, the stable slippage rate can be acquired in the whole loading process, and the influences of different slippage rate on the bonding-slipping constitutive relation can be researched.

Description

technical field [0001] The invention relates to the technical field of experimental research, in particular to a test device and method for pulling out bond slip between reinforcement and concrete. Background technique [0002] In the reinforced concrete structure, the reason why two materials with different mechanical properties, steel bar and concrete, can complement each other and work together is that apart from having similar thermal expansion coefficients, one of the most important reasons is that there is a bonding effect between the two. This effect enables stress transfer between steel bars and concrete, and has an important impact on the distribution of internal stress in reinforced concrete structures, the development of cracks, the anchorage of steel bar ends, and many other aspects. Therefore, the research on bond-slip between steel bars and concrete It is of great significance in theory and engineering application. Scholars at home and abroad have carried ou...

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Problems solved by technology

[0003] There are few research results on the influence of different slip rates on the constitutive relationship of the whole bond-slip process, the main reason is that it is difficult to achieve a stable slip rate.

There are gaps in each link of the whole test device, and the connecting rods of the test device will also be deformed during the loading process. When the displacement is used as the control method, the displacement of the testing machine is much greater than the pull-out of the steel bar due to the inclusion of the above gap and the deformation of the test device itself. slip value; while using LVDT to test the slip value as the control method, the corresponding P, I, and D parameter settings of LVDT are related to the stiffness of the specimen, and the stiffness of the load-slip relationship between the steel bar and the concrete is in the whole loading process. There are changes in the test, even a large change, and the parameter values ​​determined by the debugging before the test cannot be adjusted during the test, and the whole process control cannot be realized by using the LVDT signal

Therefore, it is difficult to obtain a stable slip rate of steel bars, so that it is impossible to quantitatively study the influence of slip rate on the constitutive relationship of the whole process of bond-slip of reinforced concrete

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