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This paper presents a cohesive model endorsed with a viscous term dependenton the crack-opening rate. It can be used to simulate fracture processesthat are sensitive to the loading rate. The model is implemented in a finiteelementbased program using the smeared crack tip method developed by Planas& Elices [which is thoroughly described in [1] G. Ruiz, Int. J. of Fracture 111:265-282, 2001]. The model is validated against three point bending tests onnotched beams of a high-strength concrete performed at five different displacementrates. The results obtained with the model match very well the experimentalones, particularly the maximum load and the work of fracture for the severalrates used in the tests. The model has also been used to perform a parametricstudy that shows that the dependencies of the work of fracture to the size ofthe specimen and to the length of the ligament are mainly attributable to rateeffects.