Zaher Alkurdi, Tamás Kovács

Abstract: Bond strength in pretensioned members is a critical factor influencing the structural integrity and durability of concrete structures. This study explores the bond behavior in such members, focusing on the flexural bond, through detailed numerical modeling. Using a validated finite element (FE) model, both simple and tensioned pull-out tests were simulated to examine the differences in bond strength and the impact of varying tension ratios. The study employed seven-wire strands and lightweight aggregate concrete, with three-dimensional (3D) elements representing the concrete and reinforcement bars. The bonded interface was modeled using 3D isoparametric gap elements with a pressure-sensitive Mohr-Coulomb frictional interface. The results indicated that pretensioning below the yield strength threshold had no significant effect on bond strength compared to the bond strength observed in the simple pull-out test. However, a decrease in bond strength was observed when the pull-out test was conducted just prior to or during the yielding of the strand, with a more substantial reduction occurring when the test was initiated after yielding. Additionally, changes in strand diameter due to the Poisson effect were more pronounced under higher stress conditions, further influencing bond strength.

Keywords: Tensioned Pull-out test, Prestressed, Bond, Pretensioning, Flexural.

Date Published: October 3, 2024
DOI: 10.11159/ijci.2024.018

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