Endochronic Theory of Inelasticity and Failure of Concrete

A gradual accumulation of inelastic strain can be most conveniently described in terms of the so-called intrinsic time, whose increment depends on the time increment as well as the strain increments, and was previously developed for metals and is extended herein to concrete. It is demonstrated that the proposed model predicts quite closely: (1)Stress-strain diagrams for concretes of different strength; (2)uniaxial, biaxial, and triaxial stress-strain diagrams and failure envelopes; (3)failure envelopes for combined torsion and compression; (4)lateral strains and volume expansion in uniaxial and biaxial tests; (5)the behavior of spirally confined concrete; (6) hysteresis loops for repeated high compression; (7)cyclic creep up to 10⁶ cycles; (8)the strain rate effect; (9)the decrease of long time strength; and (10)the increase of short-time strength due to low stress creep.