Self-balancing reinforced concrete bonding and anchoring performance test instrument

Abstract

A self-balancing reinforced concrete bonding and anchoring performance test instrument. An inner frame is movably installed on a top plate of an outer frame. A vertical column on the inner frame is slidingly connected to the top plate of the outer frame. A loading device is arranged on the bottom of the inner frame. A reinforcing steel bar on the upper end of a specimen slidingly passes through the top plate of the outer frame and the top plate of the inner frame and is connected to a nut. A loading end fixing apparatus and a free end fixing apparatus are disposed respectively on the reinforcing steel bars at the two ends of the specimen, wherein at least one displacement meter is installed on each of the loading end fixing apparatus and the free end fixing apparatus. A measurement rod of each displacement meter is contact with an end surface of concrete of the specimen. A plurality of strain pieces are disposed on the reinforcing steel bar in the concrete. In the invention, by means of unique design of the loading end fixing apparatus and the free end fixing apparatus, the displacement meters are tightly fixed on the loading end and the free end of the specimen and meanwhile the loading end fixing apparatus is fixed at the interface between the reinforcing steel bar and concrete, so that the test instrument can be used for accurately measuring the sliding distance of the loading end and the free end during a loading process of the specimen.

Description

technical field [0001] The invention relates to the field of civil engineering bond-slip performance test, in particular to a self-balancing reinforced concrete bond and anchor performance tester. Background technique [0002] Bond-slip behavior is one of the most important fundamental issues in the theory of reinforced concrete structures. At present, the bond test methods used include pull-out test, beam test and axial pull test. The preparation of the test piece and the test device for the pull-out test are relatively simple, and the test results are easy to analyze. Therefore, it has been used as a benchmark for relative comparison of the bond performance of steel bars for a long time. In order to achieve the bond-slip τs For a more precise description of the constitutive relationship, the method of rebar slotting, patching, and calculation of internal slip distribution from the loaded end and free end is often used to explore bonded anchorage τs The relationship cha...

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Problems solved by technology

[0003] (1) It is very difficult to measure the slippage at the loading end. At present, there are some problems in the measurement of the slippage of the steel bar at the loading end in the current domestic drawing device because the measured slippage value includes the tensile deformation of the steel bar outside the concrete. big error

[0004] (2) At present, many scientific research institutions need to use external loading equipment such as universal testing machines when doing pull-out tests. Therefore, it is necessary to move the pull-out frame around. The operation is very cumbersome and requires a lot of manpower.

[0005] (3) At present, many drawing frames are used in China, and the specimens are directly exposed outside during the drawing test, which is not convenient for the experimenters to observe the damage development form of the specimens, and also increases certain unsafe factors

[0006] (4) It is very difficult to measure the bond stress of steel bars. The measurement of bond stress in the pull-out test of steel bars has always been a difficult problem for researchers.

[0007] Chinese patent document CN104122201A discloses a reinforced concrete bond stress and slip measurement device, which adopts a structure with displacement sensors, but in this structure, due to the narrow installation space, the installed displacement sensors all adopt a cantilever structure, which affects the measurement accuracy

And special equipment such as universal testing machine is required

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