Research On Cracking Developing And Identification Of Concrete Bridge Based On Information Entropy

Firstly, the constitutive model of concrete materials, the method of modal-damage identification and the theory of information entropy are reviewed in this paper. A new method is proposed which is combined the energy method and information entropy to identify the crack of concrete bridge as well as the stage of crack. Some key technical issues about the concrete crack evolution based on entropy theory have been solved. Then, A complete set of criteria for health inspection of the concrete bridge structure have provided.Based on dissipative system characteristics, the strain energy entropy formula is inferred to seek the concrete crack evolution, and also the element damage degree judgment formula is established to describe distribution of the unit strain energy entropy by combining the energy method and the theory of information entropy. The strain energy entropy about the concrete bridge crack initiation, stable growth stage,instability and failure stages had been systematic analyzed. Then the strain energy entropy curves of crack evolution had been plotted. Finally, to simulate the change of continuous beam structural strain energy entropy about the crack evolution through the finite element software Midas/FEA, then demonstrating the feasibility of the theory in this paper.The evolution of concrete crack had been analyzed by the the influences of the load and temperature. Inferring the influence function of strain energy entropy of the concrete crack based on the information entropy theory, informationize load and temperature factor, and conducting the factors function of concrete crack in the meantime. Calculating the effect of concrete crack evolution based on temperature and load factors by the finite element software Midas/FEA.A modal strain ratio energy entropy function derived through combing the information entropy and modal strain energy density method that based on the features of dissipative system, information entropy theory and the method of modal-damage identification. Proposing recognize the crack position by the change of modal strain ratio energy entropy between the crack occur and before. Using the finite element software Midas/FEA, simulating single point of damage, two symmetric damages and two asymmetric damages. And then extracting corresponding data and using Matlab to calculate the entropy changes of modal strain ratio energy entropybefore and after concrete cracking and drawing a damage identification map,verifying that modal strain ratio energy entropy can precisely locate the cracks.Based on the finite element theory of concrete structure, calculating unit strain energy entropy by divided the structure, analyzing the changes of strain energy entropy between the crack appearance, establishing unit damage degree formula and inferring the calculation formulas of the width and depth of the crack. Finally,comprehensive evaluating the structural state by the gained data.Then, based on the theory mentioned in the verification of Midas/FEA, the crack width and depth can be calculated.The full text demonstrates the strain energy entropy change for concrete structure cracks evolution and verifies the advantage in the concrete cracks identification with two different information entropy indexes through the combination of the theoretical analysis and the numerical simulation, which is aimed at to providing a new and feasible method for the concrete cracks research and identification.