Relation of stress-strain for concrete material subjected to biaxial tensile stress

Based on the analysis of the failure feature of concrete material subjected to biaxial tensile loading from mesoscopic fracture, a rational damage variable and function of free energy are introduced.With the help of irreversible mechanics theory,a damage constitutional model of concrete under biaxial tensile loadings is put forward.Damage can be determined by damage energy release ratio and the coefficients used in the model can be uniquely determined by the experiments on the concrete subjected to monotonic axial tensile loading,the relationship of stress and strain is established.The trail and repeated are evaded.The strain at the peak under different stress ratio are also gotten by the condition of the stress-strain curve on the characteristic points.It is found that theoretical results have a good agreement with experiments'.