Characterization of crack-bridging and size effect on ultra-high performance fibre reinforced concrete under fatigue loading

Abstract

The use of ultra-high performance fibre-reinforced concrete (UHPFRC) has become popular owing to its high strength, durability and toughness characteristics compared to conventional concrete. In this work, experimental investigations have been carried out to examine the fracture behaviour of UHPFRC beam specimens under static and fatigue loading with an emphasis on understanding the size effect. Experimental results of both monotonic and fatigue have been utilized to develop a mathematical formulation for predicting crack bridging degradation considering the fatigue loading history. Subsequently, the size effect behaviour on the crack-bridging strength of UHPFRC beams under fatigue loading conditions has been explored. An algorithm has been developed to predict crack propagation as a function of load cycles and to estimate the fatigue life corresponding to any load amplitude, accounting for the size effect. The crack-bridging strength has been observed to decrease with an increase in specimen size, lowering the fatigue life.