Prediction of size effect and non-linear crack growth in plain concrete under fatigue loading

• Determine cyclic induced bridging stresses in a plain concrete TPBSEN specimen using inverse analysis under cyclic loading.
• Equivalent crack resistance is derived using the back-calculated bridging stresses.
• The equivalent crack resistance curve was used to predict non-linear crack growth and size effect under high cycle fatigue.
• The cyclic fracture toughness was approximately 80% of the total fracture toughness.

A new method is proposed that uses inverse analysis to calculate cyclic induced bridging stresses along a dominant crack face in a plain concrete three-point bending single edge notch specimen. Peak to peak low cycle fatigue data is used to back-calculate the bridging stresses and an equivalent crack resistance curve is derived with a weight function. Fourteen specimens were tested under low cycle fatigue and two were tested under high cycle fatigue. The results of this study indicate that the equivalent cyclic crack resistance curve obtained under low cycle fatigue can be used to predict the equivalent cyclic crack resistance under high cycle fatigue and explain the decelerating crack growth phenomenon and size effect in plain Portland cement concrete.