| Concrete which is usually hybrid material, always experience load history before dynamic load in practical work, so its mechanical properties will be affected by the load history. Compared to the static mechanical properties of concrete, the dynamic mechanical properties is more complex, concrete often bears earthquake, wind load, impact load and other loads in use, thus, the dynamic mechanical properties plays a crucial role in the safety and stability of the structure.The selection of test device and method will have a great influence on the test results, this paper combines the design and scheme of the test and uses MTS hydraulic servo loading device and advanced data acquisition instrument, appropriate concrete test piece manufacturing method and loading schemes for different strength grade and conducts the bending experimental study under the dynamic loads.In this paper, C45, C50, C55 three strength grades of specimens were analyzed on their mechanical properties under dynamic load. Ata strain rate of 10-6s-1, 10-5s-1, 10-4s-1, dynamic direct damage and experienced history of direct damage, two different stress conditions of the dynamic flexural tensile failure. Through the test data analyzing and summing up, this paper gains the research of load history and strain rate a flexural elastic modulus, Poisson’s ratio, flexural strain, flexural strength and flexural stress effects, stress-strain curves of test on concrete. Conclusions are as follows: with the increase of strain rate, due to loading history bending tensile and flexural tensile damage directly compared to the situation, three kinds of strength grade of concrete flexural elastic modulus, flexural tensile strain, flexural strength has a certain degree of improvement, the Poisson’s ratio hardly changes. Finally, the cracking mechanism of concrete was analyzed, the result showed that with the increase of strain rate, concrete coarse aggregate destruction are more obvious and the failure surfaces are also more flat. |
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