Strain Based Approach to the Fatigue Evolution Modeling of Concrete under Tension-Tension Loading

Abstract

Abstract: Strain based Approach to the Fatigue Evolution Modeling of Concrete under Uniaxial Tension-Tension Loading plays a very important role in the evaluation of the material properties of concrete utilizing strain analysis methods, the nonlinear fatigue strain evolution model is proposed, and the hypothesis of recycle ratio related fatigue strain amplitude causes stiffness degradation and inelastic deformation is briefly described which are the essential material properties of concrete. This paper presents Fatigue Strain based Approach to the Damage evolution Model of concrete and also another model in strain space is developed by using the general framework of interior variable theory of continuum thermodynamics. It is argued that within the damage outward of given strain states the unloading-reloading cycles (fatigue loading) stimulate the nucleation and growth microcracks in concrete, which will result in stiffness reductions and plastic deformation, and hence material is termed as damaged. The evolution curves of fatigue strain modulus have three stages, namely, variation phase, linear change stage, and convergence stage. The fatigue strain evolution curve in figure is from the lower left corner to the upper right corner and in another Model damage is reflected through the fourth-order stiffness parameters through the consistency equations related to cycle dependent damage in strain based modelling. The model is capable of predicting stiffness degradation, inelastic deformation and strength reduction under fatigue loading and compared against experimental results. Keywords: Strain based approach; fatigue evolution; stiffness degradation; fatigue strain; Thermodynamics; damage, response tensors.