Research On Mechanism And Improvement Of Concrete Anti-crack Test Based On ANSYS

Mass concrete structures play an important role in engineering construction. Alongwith the development of large concrete structures in modern engineering，surface cracksof early concrete have become the research focus of the engineers. Research shows thatmany factors would lead to early cracking of the concrete, and the shrinkage deformationis one of them.. To solve the problem of early cracks of concrete, the physical mechanismof concrete early shrinkage cracking must be understood. It is also very important totaking anti-crack test which can reflect real working conditions of concrete to determineits anti-crack property. Ring-test is the most mature concrete anti-crack test method. Itcan involve the influence of the concrete shrinkage, creep, elastic modulus, and otherfactors. But the present ring test method has some shortcomings such as long testing time,poor sensitivity. Therefore, analyzing the mechanism of concrete cracking in the ringcrack test and studying the influence various parameters on the cracking time in order toimprove the test mode are very necessary to reduce concrete crack and increase thedurability of concrete structures. This paper focus on the following works:(1) In order to study the concrete specimens of early shrinkage cracking performance,observation of the specimen of early cracking time, using the ring constrained test device.In this paper, the same water-cement ratio of concrete and cement mortar specimens aretested by the early ring crack test respectively. Through the observation on the surface ofthe circumferential strain changes to measure the concrete and mortar specimenrestrained shrinkage performance. This paper details the process of the ring crack test andthe test results were analyzed;(2) Through the reading of literature, to grasp the concrete shrinkage and deformationtheory, analysis of the factors that affect the shrinkage of concrete at early age. Based onthe diffusion law and the law of conservation of mass, determine the mathematical modelof the concrete internal humidity field calculated, and the model parameters and initialand boundary conditions are discussed; Finally, analyzed the shrinkage deformation ofconcrete generated under the constraints;(3)The finite element software ANSYS is simply introduced in this paper. UsingANSYS software, the ring cracking test model was simulation calculated, the humidityand stress field calculations were analyzed. In order to verify the finite element softwareANSYS simulation results, simulation results were validated by experimental results. Finally, the text, using ANSYS software calculated the influence of different factors onthe early cracking of the ring crack test and calculation results are analyzed;(4) Based on the calculated results, the size of the ring crack test model has beenimproved in this paper. Using ANSYS software simulation the different short-long axisof the elliptical ring crack model is analyzed. Application of probability analysis modulereliability of corresponding elliptic ring was proposed.