Concrete Damage Behavior Characteristics

During the shaping process of the concrete structures or members, there will exist defects such as small crevices in the body or on the surface inevitably, that is to say, the existence of original damages is unavoidable. Under the acting of the outside factor, the original damages will develop and the new damages will appear. When the accumulation of the damages reach a certain degree, the macro-damages will appear and new damages will also produce at the tip of these macro-damages. The new accumulation of the damages will cause the extension of the macro-damages, and the continuous extension is very dangerous to the stability of the structure. So, it is important to analyze the developing law of the damages and the macro-damages in concrete, acquaint the stress field, displacement field and damage field in structure for preventing the destruction in concrete structure caused by damage and fracture.Based on the previous and through the uniaxial tension damage experiment and comparing to the uniaxial compression damage experiment, the paper makes research on the anisotropism of the damage and the difference of the damage between the uniaxial tension and the uniaxial compression, combining with orthogonal anistropic damage model and exponent function damage developing equation. Through the formulae deduction, the damages caused by the same absolute value tension and compression strain have the comparing character in some extent and corresponding decay coefficient. Based on the FEM program on fracture of plane structure developed by professor Fu Xiaoling of Ho Hai University, a two demension damage and fracture finite program package which is programed in FORTRAN 90 language is developed. The paper adopts the plane -eight-nodes isoparameters element and compute the developing law of the damage and macro-damage of plane structure under load. Considering the original damage and tension and compression damage at the same time, the paper adopts the more reasonable concrete constitute relation of two demension and exponent function model. Through the several computational examples, the paper makes research on the damage and fracture developing law and the related contours are given. The computational result is good comparing to the fact condition, so, this program is a good computation tool for the damage field analysis of the plane structure.