Abstract: According to test results,the obvious differences between the cracks of a concrete sample and a practical concrete structure are understood,and a constitutive model based on strain space is proposed.The research results show that for orifice structure to take limit strain as crack criterion is more rational than to use maximum principle stress.The computed data adopting proposed criterion are good consistent with the results of experiment. 

Key words:  , model test, constitutive relationship, crack, strain