Experimental and analytical study on the bending performance of UHPC‐NC narrow steel box composite beams under negative moments

Abstract A novel UHPC‐NC composite structure was proposed to enhance the load‐bearing capacity of concrete beam bridges under negative bending moments. Parameters including steel fiber content in UHPC, reinforcement ratio, and steel box filling height were varied across 8 UHPC‐NC narrow steel box composite beam specimens. The study involved testing, and measurement of failure modes, crack distribution, deformation characteristics, and crack widths. Additionally, a method for calculating maximum crack widths was developed based on crack distribution patterns. Furthermore, a computational model for predicting the ultimate bearing capacity of UHPC‐NC narrow steel box composite beams was constructed. The computed results aligned closely with experimental findings, validating the accuracy of the proposed computational model.