Numerical and Experimental Investigation on Time-Dependent Crack Extension in Concrete Under Sustained Loads

For concrete structures dominated by fracture failure, e.g., containment and gravity dams, sustained load deformations primarily arise from crack extension and concrete viscoelasticity. As cracks progressively grow under sustained loads, accurate prediction of the time-dependent fracture process in concrete accounting for crack-viscoelasticity interactions are crucial for the stability and safe design of concrete structures. This paper presents an initial fracture toughness ((Formula presented.))-based numerical model to predict the time-dependent crack extension in concrete under sustained loads. The model integrates a time-dependent tension-softening constitutive relation, the generalized Kelvin chain model for viscoelastic behavior and (Formula presented.) -based criterion for crack extension. The accuracy of the model was verified with two sets of experimental data available in the literature. The results indicated that the tension-softening constitutive law that quantifies the relation cohesive stress (s_w), loading time (t), and COD can be successfully implemented in the numerical model. The predicted CMOD versus time and crack length versus time curves show good agreements with the test results regardless of loading level, specimen configuration and material property, demonstrating the predictive capability of the model in describing the crack extension in concrete exposed to sustained loads.