Lattice Modeling For Cracking Of Reinforced Concrete Regarding Corrosion Expansion Of Rebar2

The rebar is corroded by the external environment, and then produces the volume expansion, which causes the surrounding concrete to be squeezed. With the increase of the corrosion of the rebar, the concrete cover will crack due to the tension stress. When cracks develop to a certain extent, the concrete cover will peel off, which will seriously affect the durability of the concrete structure. Therefore, it is of great significance to study the corrosion cracking of reinforced concrete structures in the study of the durability of structures.This paper mainly provided numerical simulation of the cracking of concrete structures due to corrosion expansion with lattice model through the MATLAB programming. Meanwhile, the model was also used to study the effect of the thickness of concrete cover, bar diameter, concrete tensile strength and coarse aggregate particle size on the concrete cracking due to corrosion. The main research contents and results of the research were as follows:(1) The microstructure and mechanical properties of the concrete were introduced. A kind of aggregate throwing method was put forward, which greatly improved the aggregate volume of the rate of delivery, and the two-dimensional random aggregate model of concrete was also built through programming in MATLAB.(2) According to the basic principle the lattice model, the two-dimensional lattice concrete constitutive model was established based on the random aggregate model of concrete. The reinforcement corrosive morphology and its application were also summarized. On the basis of the reinforcement corrosive morphology, forced displacement was applied to simulate concrete cracking due to corrosion.(3) The surrounding concrete bilinear quadrilateral element model was established. The force transmission between the lattice type model(core concrete) and bilinear quadrilateral element model(the surrounding concrete) was realized through node interface coupling, so as to establish a mixed model, which is used to simulate concrete cracking due to corrosion in consideration of the boundary constraint.(4) Cracking of concrete due to corrosion of rebar at plane edge and corner of cross section was simulated with the completed program. The graph of concrete cracking due to corrosion and the relation curve crack between the crack width and corrosion expansion quantity of the steel bar are drawn. Besides, the similarities and differences of cracking due to corrosion expansion between the circular aggregate and elliptical aggregate were compared.(5) Non angle reinforced concrete corrosive cracking taken as an example, the effect of the concrete cover thickness, rebar diameter, the tensile strength of concrete and aggregate size on concrete cracking due to rebar corrosion were studied with the relatively actual aggregate morphology of elliptical aggregates.(6) In view of the two representative experiments, the numerical simulation was carried out with the method introduced in this paper. Thus, the feasibility and the defects of the present method were demonstrated by comparing and analyzing the simulation results and the experimental results.