Finite Element Analysis (FEA) For Prestressed Concrete Beam With Cracks

Nonlinear finite element analysis of reinforced concrete strucutres is an importantresearch direction in structural analysis field. It can accurately analyse theperformance of the complex structure in engineering practice, describe the shapingand development of the crack in structure, evalue the limiting bearing capacity andreliability of the structure, reflect a weak part of the strucutre which make sense to theoptimal design of the structure and is of guiding evalue of the analysis, design andconstruction of the practical structure. Based on finite element software ANSYS, anonlinear three-dimensional finite element reinforced concrete model has beenestablished. A complete study on the constitutive relations, establishment of model,crack model has been give in this paper. The stress and displacement status in thereinforced concrete box girder under different load and prestress case has beeninvestigated. The parameter numerical analysis has drawn some useful conclusions.The main analysis in this paper are as follows:In chapter1, by reviewing on large mass of literatures and combining thepractical engineering, the crack analysis on reinforced concrete has been retrospectedand discussed. Firstly, the wide application of the reinforced concrete beam has beendiscussed; and then the damage analysis and reason of the crack initiation inreinforced concrete beam has been discussed, and accordingly discuss the crackpropagation control and dealing method has been analysed; at last, the research stateand propagation on crack in reinfored concrete structure has been summarised.In chaper2, the finite element method is introduced at first; and then thecomparison between some important problems concerning strucutural model is given,and accordingly the model adopted in this paper is established, i.e. the constitutiverelations and failure criterion. The general used constitutional relations and failurecriterion in the finite element analysis of the reinforced concrete structure is beendiscussed and compared as well as the nonlinear material model. The applicationcondition of the material medal is discussed which give the final model used in thispaper, the Ottosen model and nonlinear total model constitutive relations. Theconstitutive relation and material model of the steel adopted in this paper has beengiven at last.In chaper3, introduced the finite element analysis model and unit selection areintroduced and the results of numerical examples. In the reinforced concrete structurefinite element analysis, considering its is composed of two kinds of material components, must choose the proper finite element model can calculate study, thischapter presents with reinforced film of eight node hexahedron element for reinforcedconcrete beam, and deduced its stiffness matrix.In chaper4,the monolithic reinforced concrete modeling method, using diffusecrack analysis method, based on the project of commercial finite element softwareANSYS to establish the reinforced concrete box girder model, and through thedifferent loading parameters, analysis of the reinforced concrete in the external loadunder the action of stress and displacement level, analyses the cracking and crushingcrack form.In chaper5, the finite element method modeling of the nonlinear property of thereinforced concrete strucutre with prestress applied in temperature form has beenmainly discussed. The effect of external tempareture condition on reinforced concretestrucutres is great either in constructing process or in serve. Due to the change ofelastic module with the time and the complexity and non-uniform distribution of thetemperature in reinforced concrete strucutre, the stress would be aroused bytemperature in the reinforced concrete structure(mainly temperature stress andtemperature deformation). In this chapter, the stress and displacement cloud map aswell as the crack condition of the reinforced concrete with prestress under externalmechanical load are investigated.