Analytical and Finite Element Modeling for Time-Dependent Deflection of Ultra-High-Performance Fiber-Reinforced Concrete Beam

Ultra-high-performance fiber-reinforced concrete (UHPFRC) has emerged as an advanced concrete technology in the sustainable building industry. It can provide better infrastructural development in terms of strength, ductility, toughness, and stiffness than traditional concrete. This paper aims to analytically determine the time-dependent deflection (i.e., creep) of the UHPFRC beam with varying amounts of steel fiber addition. The age-adjusted effective modulus method was used to anticipate the time-dependent deflection of the UHPFRC beam. Experimental data related to time-dependent properties of UHPFRC were extracted from the literature to develop new formulas for creep coefficient and shrinkage strain through curve fitting and data validation. A new range of aging coefficient was proposed for UHPFRC through trial according to the ACI code. The existing shrinkage-induced curvature formula for cracked sections was modified using data validation. The analytical study incorporated all the proposed formulations and coefficient values to anticipate the UHPFRC beam's time-dependent deflection theoretically. Along with the analytic analysis, Finite Element Method (FEM) was also employed to predict the time-dependent deflection of the UHPFRC beam. It was found that for different percentages of steel fibers, both the FEM and the proposed analytical approaches conservatively estimate the deflection values, with an average deviation of around 20% from the experimental results. The accuracy and validation of the proposed theoretical formulation to predict the time-dependent deflection of UHPFRC beams were also demonstrated through statistical analysis.