Fracture mechanism and interface behavior of prestressed segmental UFC beams with a circular cross section under bending

This research investigates the behavior of concrete tubular segmental beams prestressed with PC bars, focusing on the load-deflection characteristics and failure mechanisms.The interface parameter obtained from experimental results provides insight into modeling the epoxy joints used in large wind turbine towers.Specimen S8-JI2 exhibited failure patterns, load-deflection behavior, and tensile stress comparable to those observed in the experimental specimen.A unique failure mode dominated by longitudinal cracks was observed, explained by the arch mechanism activated when the interface joint opened.This led to a shift in the neutral axis, resulting in compressive stress transfer within the UFC and generating lateral stresses, which caused horizontal cracks.The study also found that reducing steel fiber content from 2% to 1.2% resulted in reduced load-carrying capacity and altered failure patterns, with the arch mechanism becoming more prominent in the lower fiber content specimen.Additionally, normal concrete specimens exhibited pronounced diagonal cracking due to interface opening, particularly in the central segment of the beam.