Tensile strength based two-phase fatigue process prediction model of prestressed UHPC beams

Abstract

A fatigue process prediction model of prestressed UHPC beams was established leveraging the tensile strength contribution of UHPC; based on the stress analysis of the UHPC beam, the fatigue process was divided into two phases: uncracked and cracked. The calculation results of the model were compared with the test results in other literatures, and the applicability of the model was verified. A railway prestressed UHPC box girder was taken as an example, and the effects of UHPC strength, prestress value, stress amplitude, reinforcement ratio, and span on the fatigue properties were investigated. The results verified the availability of the fatigue process prediction model of the prestressed UHPC beam; the error of UHPC strain and mid-span deflection development during the fatigue process is within 7%. The investigation of parameters showed that the prestress value, stress amplitude, and span have a great influence on fatigue life, while UHPC strength has a minor impact. At the early stage of the fatigue process, UHPC strength has a massive influence on the growth of strain, while other factors have almost no effect. At the later stage of the fatigue process, the prestress value, stress amplitude, and span have a significant impact on the growth of strain.