Experimental research on fatigue behavior of prestressed ultra-high performance concrete beams with high-strength steel bars

Abstract

Ultra-High Performance Concrete (UHPC) is a new type of cement-based composite material that exhibits exceptional compressive strength, tensile properties and durability compared to ordinary concrete. Comprehensive research on the flexural fatigue behavior of prestressed UHPC beams is presented in this paper. The failure mode of the fatigue beam is the fatigue fracture of the tensile steel bar in the pure bending section. In the fatigue process, the fatigue behaviors of prestressed UHPC beams including crack width, midspan deflection, the strain of UHPC in compression zone and strain of high-strength steel bars exhibit two stages which are corresponding to damage initiation, steady damage propagation. The residual deflection at the midspan increases with the increase of fatigue cycles. The prestressed UHPC beam reinforced with high-strength steel bars shows stable structural behavior even after concrete cracking. The S–N expression of prestressed UHPC beam with consideration of the influence of stress amplitude of high-strength steel bars is proposed. The stiffness degradation formula of the fatigue beam and calculation methods of fatigue crack width and fatigue deflection are proposed.