Flexural Performance of UHPC-Reinforced Concrete T-Beams: Experimental and Numerical Investigations

This study investigates the flexural performance of ultra-high performance concrete (UHPC) in reinforced concrete T-beams, focusing on the effects of interfacial treatments. Three concrete T-beam specimens were fabricated and tested: a control beam (RC-T), a UHPC-reinforced beam with a chiseled interface (UN-C-50F), and a UHPC-reinforced beam featuring both a chiseled interface and anchored steel rebars (UN-CS-50F). The test results indicated that both chiseling and the incorporation of anchored rebars effectively created a synergistic combination between the concrete T-beam and the UHPC reinforcement layer, with the UN-CS-50F exhibiting the highest flexural resistance. The cracking load and ultimate load of UN-CS-50F were 221.5% and 40.8%, respectively, higher than those of the RC-T. Finite element (FE) models were developed to provide further insights into the behavior of the UHPC-reinforced T-beams, showing a maximum deviation of just 8% when validated against experimental data. A parametric analysis varied the height, thickness, and material strength of the UHPC reinforcement layer based on the validated FE model, revealing that increasing the UHPC layer thickness from 30 to 50 mm improved the ultimate resistance by 20% while reducing the UHPC reinforcement height from 440 to 300 mm led to a 10% decrease in bending resistance. The interfacial anchoring rebars significantly reduced crack propagation and enhanced stress redistribution, highlighting the importance of strengthening interfacial bonds and optimizing geometric parameters of UHPC for improved T-beam performance. These findings offer valuable insights for the design and retrofitting of UHPC-reinforced bridge girders.