Depth-dependent flexural behavior of plain and bar-reinforced ultra-high-performance hybrid fiber-reinforced concrete –analytical, numerical, and uncertainty modeling

Abstract

Ultra-high-performance concrete (UHPC) has been the perfect material for precast, marine, defense, and high-rise structures due to its outstanding features, including high ductility, compressive strength, and enhanced durability. UHPC technology has gained wide attention for various applications. Government initiatives, however, have largely led to the development of these projects. The UHPC has not been widely adopted since there are no reliable and accurate codified formulas for predicting load-carrying capacity, which remains a significant obstacle. First, this study evaluated the applicability of popular international design guidelines for predicting the moment capacity of fiber-reinforced UHPC (UHFRC) beams. In addition, a nonlinear numerical approach for a robust model to predict the moment–curvature of UHFRC beams was developed and validated. The structural safety of UHFRC beams using a multivariate nonlinear probability model was verified. As beam depth increased, the reliability index decreased slightly, which could be attributed to its significant impact on the reliability index. The presence of reinforcement bars significantly affects the reliability index as its percentage increases. All reinforced beams with a depth of 120 mm or more and steel bars had a reliability index greater than 3.0. In the study, bar reinforcement is demonstrated to be a vital component of the UHFRC beam for ensuring structural integrity.