Numerical modeling of delayed damage and failure of concrete structures under sustained loading.

The combination of subcritical damage growth and creep deformation can cause delayed failure of concrete materials. Such a time-dependent failure behavior adds a new consideration in design of concrete structures. To investigate this behavior, a time-dependent constitutive model for concrete is proposed. The model is anchored by integration of the continuum damage mechanics and nonlinear creep theory. It captures several essential mechanisms responsible for delayed failure behavior of concrete, which include instantaneous softening damage, plasticity, subcritical damage growth, and nonlinear creep. The model is calibrated by the creep experiments on concrete specimens under uniaxial compression and three-point bending. It is shown that the model can well capture the time-dependent deformation and failure of concrete structures under a wide range of loading levels. The contributions of different individual mechanisms to the overall structural response are investigated. The calibrated model is then used to simulate the response of a reinforced concrete frame under sustained loading. The simulation yields the stress-life curve, which is an essential metric describing the delayed failure behavior of concrete structures. • A time-dependent constitutive model for concrete is developed. • The proposed model considers instantaneous softening damage, plasticity, subcritical damage growth and nonlinear creep. • Systematic calibration of concrete creep experiments at different loading levels is performed. • The simulation of delayed failure of reinforced concrete frame yields the stress-life curve. • The time-dependent effect of Vierendeel frame action is investigated. [ABSTRACT FROM AUTHOR]