Device for testing fracture energy of concrete by three-point bending beam without self-gravity doing work

Abstract

The invention discloses a method for testing the fracture energy of concrete by a three-point bending beam without self-gravity doing work, and belongs to the technical field of civil engineering. The method is characterized by manufacturing a concrete beam of which the total length is 1.912 times of clear span. A test device comprises a sensor, an angle steel connecting rod, a clip-on extensometer, a sheet bar and the like. Through a tested load-deflection curve, the fracture energy of the concrete is calculated directly without fitting a curve. The fracture energy of the concrete is the ratio of an area enclosed by the load-deflection (the work done by a load) to the area of a beam ligament. The device for testing the fracture energy of the concrete by the three-point bending beam without self-gravity doing work has the advantages that: the self-gravity of a concrete test piece is counteracted without adding any connecting rod or weight to counteract the work done by the self-gravity; requirements on the rigidity of a test machine are low; the fracture energy is calculated without fitting the curve or calculating the work done by the gravity; calculation processes are simplified; and a test device is simple and easy to operate, so the device is suitable for small and medium laboratories with small test machine rigidity.

Description

technical field [0001] The invention belongs to the technical field of civil engineering, and relates to a concrete fracture energy testing device using a three-point bending beam. Background technique [0002] The fracture energy of concrete is an important parameter in the nonlinear analysis of concrete structures. At present, there are many methods for measuring the fracture energy in the world, but all of them are difficult to measure accurately. The specific performance is that the fracture energy measured by the test has a size effect, which is somewhat different from the theoretically defined fracture energy. The calculation of the fracture energy of concrete will be affected by the test device, the self-weight of the specimen, and the experimental data processing method. Currently the most widely used method is the three-point bending beam method recommended by RILEM to determine the fracture energy of concrete. Although the test device is simple in this method, it...

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Problems solved by technology

The disadvantages of this method are: it is necessary to conduct a large number of fracture tests of different specimen sizes, and to perform linear regression on a large amount of test data, the number of specimens is large, waste of materials and labor, and the later data processing is also cumbersome.

When calculating the fracture energy by the above methods, it is necessary to calculate the work done by the self-weight of the specimen and fit the curve measured by the test, and there are many data processing steps

In addition, the wedge splitting method can also be used to measure the fracture energy of concrete, but there are also complex processing of test auxiliary devices, and different test pieces need to be equipped with different devices, which increases the complexity of the test; there is also a method that can offset the work of self-weight The test device, but it needs to drill holes, and add steel sheets to connect the test piece and add weights to offset its own weight. The whole experimental device is complicated to make

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