Nonlinear Finite Element Analysis And Deformability Calculation Of Reinforced Concrete Beams

With increasing emphasize on structural ductility and development of displacement-based seismic design, it is urgent to have more understanding and cognition on nonlinear behavior and even post-peak behavior of structural members. Up to date, test analysis method is basically used in this study and especially in the post-peak behavior study. In fact based on finite element theory, we can completely attain the similar aim by using finite element simulation. In this paper, nonlinear finite element software, MSC.Marc, is used to simulate concrete beams of different configuration under 3-point loading, and then comparison between simulation data and test data is made.This paper introduces basic theory of reinforced concrete and nonlinear finite element method, including constitutive relation of concrete and steel bar, material model and calculation method of nonlinear finite element method.On this basis, 9 reinforced concrete beams having load test results are simulated using MSC.Marc. Comparison shows that simulation results is comparable to test results before peak load. But it is not ideal after peak load, and some analyses and discussion is also made for that. Meanwhile, deformability of the beam in maximum load point is also investigated for the following research.Based on the foregoing basic, 21 typical cantilever beams which have representative meaning are selected, and their test process under single point loading are simulated, then full study and analysis is followed about influence of dimensions and reinforcement ratio to angular displacement corresponding to yield point and peak load point. Calculation formulas of two kinds of angular displacement are derived by the thought of theoretical derivation first and practical fitting afterwards. Contrastively, the former is derived by strictly mathematical method on the basis of the assumption of plane section and linear distribution of curvature along beam, and the later is derived on the basis of frontal analysis results and empirical conclusions. Subsequently the rationality of the calculation formulas is investigated. Finally, this paper discuss influence of span-depth ratio and reinforcement ratio on angular displacement again from perspective of Calculation formulas, and effect of other related factors on angular displacement of beam are also discussed.