Analysis On Slip Performance Of Interfaces Between Steel And Concrete

Reinforced concrete is composed of concrete, steel, interfaces between concrete and steel, the behavior at macroscale in failure process of reinforced concrete is dependent on the mesoscale structure details and properties of its three phases. Analyzing the properties of interfaces between concrete and steel is beneficial to understand bonding failure mechanism in its service. As an important composition of concrete, cement mortar consists of fine aggregate and cement, with a lot of initial defects. Understanding the effect of mesoscale structure details on the properties of cement mortar is important to the evaluation of ement mortar and the development of new kinds of concrete materials.This paper respectively established cement mortar multiphase model and the three-phase reinforced con-crete model. Further more, the influence of mesoscale structure for its properties has been studied based on the above models, which laid a solid foundation for the analysis of the durability of reinforced concrete. The study includes:Cement mortar multiphase model was established. Compared with traditional models, it is able to intro-duce air bubbles which emerged in the mixing process as initial defects, and control its content and distribution. It is efficient to analyze the influence of the cement strength and initial defects for the performance of cement mortar in the axial tensile process.Compiled random aggregate gerneration program with the area as its control condition. It can accurately controll porosity and fine aggregate content, avoid the messy process of manually delivery and greatly improve the efficiency of the establishment of the model. Combining with the commercial finite element software, a program of integration of the analysis was presented, it effectively reduces the model establishment and data extraction time, which laid a foundation for numerical simulation of large quantities calculation.Established the three-phase reinforced concrete model. Based on the practical observation, it defined the bonding interface between steel bar and concrete as a layer of third phase material which has a certain geometry size and the actual material properties. In the process to analyse the reinforced concrete bonding failure principle, compared to the method of filling the none geometry finite element unit with slip constitutive relation, the three-phase model is more reasonable.The three-phase reinforced concrete model was used to analyse the numerical simulation of reinforced concrete pullout test process, which did a good job at analyzing the influence of mesoscale structure details on the properties of the reinforced concrete macroscopic drawing features.