Abstract
Addition of steel fibers to high strength concrete (HSC) improves its post-peak behavior and energy absorbing capability, which can be described well in term of toughness. This paper attempts to obtain both analytically and experimentally the efficiency of steel fibers in HSC columns with hybrid confinement of transverse reinforcement and steel fibers. Toughness ratio (TR) to quantify the confinement efficiency of HSC columns with hybrid confinement is proposed through a regression analysis by involving sixty-nine TRs of HSC without steel fibers and twenty-seven TRs of HSC with hybrid of transverse reinforcement and steel fibers. The proposed TR equation was further verified by compression tests of seventeen HSC columns conducted in this study, where twelve specimens were reinforced by high strength rebars in longitudinal and transverse directions. The results show that the efficiency of steel fibers in concrete depends on transverse reinforcement spacing, where the steel fibers are more effective if the spacing transverse reinforcement becomes larger in the range of 0.25–1 effective depth of the section column. Furthermore, the axial load–strain curves were developed by employing finite element software (OpenSees) for simulating the response of the structural system. Comparisons between numerical and experimental axial load–strain curves were carried out.
Highlights
High strength concrete (HSC) has been increasingly used in reinforced concrete columns of high-rise buildings in recent years to further reduce member section size of the lower-story column and the concrete volume for the entire building structure [1,2]
That the concrete turns more brittle if its compressive strength increases, and the confinement provided to HSC is less effective than in normal-strength concrete (NSC) [1,2,3]
In ACI 318-2014, additional transverse reinforcement is very much required for high strength concrete [4]
Summary
High strength concrete (HSC) has been increasingly used in reinforced concrete columns of high-rise buildings in recent years to further reduce member section size of the lower-story column and the concrete volume for the entire building structure [1,2]. That the concrete turns more brittle if its compressive strength increases, and the confinement provided to HSC is less effective than in normal-strength concrete (NSC) [1,2,3]. Adding short and discontinuous steel fibers can be an alternative to modify the brittle nature of HSC to ductile response in compression [1,2,5]. Several research studies showed that adding steel fibers to a NSC or HSC could improve its post-peak behavior and toughness [1,2,6,7,8,9,10,11,12,13]
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