Abstract
Fracture parameters for elasto-plastic materials were investigated. Cohesive force model concept was employed to modeling the fracture process of quasi-brittle materials with fracture process zone. Tension softening diagram as the constitutive equation for the cohesive zone was estimated numerically by the poly-linear approximation analysis method with the data of load-loadpoint displacement curve. The energy consumed in 'cohesive zone (dW_f) is calculated by integrating the work done by cohesive force acting on the fictitious crack surface. Fracture. parameters for elasto-plastic materials, such as energy release rate G_p, R-curve, G_F ^<TSD>, K_<IC>^5 were estimated based on the value of dW_f. The energy consumption measured by off-set test for notched concrete beam specimen agrees with the result of numerical analysis. Fracture parameters for concretes were measured and their characteristics were discussed.
