Ultrahigh Performance Concrete Beams with Transverse Openings: Evaluating Effects and Reinforcement Strategies

This paper evaluates the behavior of ultrahigh performance concrete (UHPC) beams with transverse openings, a topic with practical implications that has not been studied thus far. Various parameters were examined; including the opening shape, location, and height; compressive strength of UHPC ( f c ′ ); internal steel reinforcement ratio; and using externally bonded fiber-reinforced polymer (FRP) sheets to reinforce the opening region. A robust nonlinear finite-element model was validated with two different experimental sets from the literature and used in a comprehensive parametric study totaling 104 specimens. The results show that, while openings in general inversely affect the UHPC beam strength and stiffness, the impact corresponds with the opening’s shape, height, and reinforcement ratio. Smaller openings near the supports have much less impact than those with larger sizes placed in the middle part. Stress concentrations are observed around the opening’s edges, causing higher stresses in the surrounding regions. Applying FRP sheets resulted in various strength and stiffness recoveries, dependent on the composite length. Increasing f c ′ increased the beam’s peak load, which can be a design option to mitigate the effects of openings. Numerous results are presented in the manuscript offering guidance for proper selection and placement of openings in field applications.