Concrete fracture test system and test method thereof

Abstract

The invention relates to a concrete fracture test system and a test method thereof, and belongs to the technical field of concrete material performance test. The system comprises a measurement system and a data acquisition and processing system; a support for supporting a concrete test piece and even cushion posts symmetrically positioned on the surrounding side of the concrete test piece are arranged on a pressure tester platform of the measurement system; and springs which extend out of the tops of the cushion posts and are higher than pressure sensors are sleeved on the cushion posts. The method comprises the following steps of: when a top plate moves relative to the platform by adopting the system, making the top plate contact the springs and then contact the pressure sensors; when the top plate is contacted with the pressure sensors, controlling the load loaded onto the concrete test piece to be continuously loaded with low loading rate till the concrete test piece cracks, destabilizes and is damaged; and meanwhile, acquiring a load signal and a crack opening displacement signal and transmitting the signals to a computer. The system and the method can acquire a fine load-displacement curve so as to calculate an accurate concrete double-K fracture parameter.

Description

technical field [0001] The invention relates to a system for testing concrete fracture performance and a testing method thereof, belonging to the technical field of concrete material performance testing. Background technique [0002] Fracture toughness of concrete is an important basis for analyzing concrete crack resistance and crack propagation stability of buildings in hydropower, water conservancy and traffic engineering concrete structure crack resistance, crack prevention design and crack evaluation. In order to understand the fracture mechanism of concrete and solve the problem of crack propagation of concrete structures, it is first necessary to correctly determine the concrete fracture parameters through the fracture test of concrete materials, and to understand the crack propagation process and the physical properties and mechanics of the area near the joint end before the concrete is unstable and fractured. Behavior. At present, the common fracture parameter of c...

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Problems solved by technology

[0004] The above existing problems with the device and method for the three-point bending beam test are that the range and accuracy of the existing testing machine are low, and the loading rate is usually 80N / s∽120N / s, which leads to: one. Test Data (such as data such as load, displacement and strain) are less in number (i.e. low acquisition frequency), resulting in rougher load-displacement curves collected, which in turn makes the calculated double K fracture parameters inaccurate, especially for small-sized concrete For beam specimens (such as cement mortar specimens), the collection Test Data The accuracy cannot meet the design requirements of concrete beam specimens; 2. The actual collection Test Data It is often necessary to stop loading the load (that is, the load cannot be continuously increased) for static collection, so that the obtained Test Data They are all discontinuous values, which cannot form a continuous load-displacement curve; 3. Often the data of the test piece just cracking and instability cannot be collected, so that the calculated double K fracture parameters are fundamentally inaccurate; 4. In the load -The descending section of the displacement curve, because the applied load rate is required to be small, otherwise the specimen is prone to sudden failure, so it is difficult to collect the process of the falling section of the load-displacement curve

[0005] Due to the above problems and defects, when the existing three-point bending beam test is used to determine the double K fracture parameters of concrete, only the collected Test Data Using empirical formulas to judge the crack initiation or instability state of concrete beam specimens, it is impossible to quantitatively verify the accuracy of the calculated double K fracture parameter values, so that the accuracy of the fracture moment cannot be determined, and the crack evolution inside the concrete cannot be deeply revealed process, it is also difficult to directly use the obtained double K fracture parameters in actual engineering

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