strength of the concrete. In Eurocode 2 [CEN 1992-1-1 (CEN 2005)], the efficiency factor was recommended as ν ¼ 0.6ð1 − fck=250Þ, taking into account the reduction of shear transfer by aggregate interlock withtheincreaseofthe compressiveconcrete strength. However,the evaluation work by Foster and Malik (2002) showed that the efficiency factor has only aweak relationship with the concrete strength and that the more important parameter is the strut inclination angle. In the MCFT by Vecchio and Collins (1986), the concept of compressionsofteningwasintroducedandtheprincipaltensilestrain,ε1, is considered to decrease the strength of concrete in compression