Behavior of RC columns strengthened with UHPFRC jackets through grooving method under eccentric loading: A comparative evaluation of steel and synthetic macro fibers in UHPFRC

Abstract

This study aims to examine the behavior of reinforced concrete (RC) circular columns retrofitted with ultra‐high‐performance fiber‐reinforced concrete (UHPFRC) jackets and fiber‐reinforced polymer (FRP) wraps under concentric and eccentric loading. In the present study, for the first time, UHPFRC jackets containing synthetic macro fibers (barchip) were used. The results were then compared with those obtained by UHPFRC containing steel fibers. Moreover, to improve the effect of concrete jacketing on the column behavior under eccentric loading, the innovative interface treatment of the longitudinal grooving method (GM) was applied. For these purposes, 15 such circular columns, 120 mm in diameter and 500 mm in height, were subjected to load eccentricities of 0, 30, and 60 mm. Thus, six columns were retrofitted with UHPFRC jackets 15 mm in thickness that included both steel and synthetic macro fibers (barchip) while another six were strengthened with UHPFRC jackets and intermittent glass FRP (GFRP) warps. The experimental results revealed that load‐carrying capacity raised with the increase of the load eccentricity, as evidenced by enhancements of 283%, 303%, and 401% in the loading capacity of the specimens strengthened with UHPFRC jackets containing both GFRP warps and steel fibers for eccentricities of zero, 30, and 60 mm, respectively, relative to those of the control. In addition, enhancements of 198% and 530% were recorded respectively for ductility and energy dissipation under a loading eccentricity of zero mm in specimens retrofitted with UHPFRC jackets including steel fiber and GFRP warps when compared with the same parameters in the corresponding control specimens. Finally, a previous theoretical model was adopted to derive the axial loading‐bending moment (P–M) interaction diagrams whereby the results of the present study were satisfactorily verified.

A new approach for the strength interaction diagram of FRP strengthened square steel reinforced high strength concrete columns

“…[9][10][11] Existing steel reinforced HSC columns (SRHSC columns) may need strengthening or retrofitting due to material deterioration under extreme environmental conditions, an increase in the applied load (i.e., emerging heavier trucks in transportation structures) and the change in the functions of the structures. [12][13][14] Fiber-Reinforced-Polymer (FRP) has been considered an ideal strengthening material for improving the deformation and load carrying capacity (LCC) of HSC columns due to its advantages of being free from corrosion with high fatigue resistance and stiffness, high strength-to-weight ratio, less maintenance and fast and easy installation. [15][16][17][18][19] Due to the great potential of FRP for strengthening HSC columns, a significant number of investigations have been devoted to FRP strengthened HSC columns and HSC filled FRP tube (fiber oriented in transverse direction only) in order to capture the stress-strain response and performance of HSC columns with FRP strengthening.…”

“…Existing steel reinforced HSC columns (SRHSC columns) may need strengthening or retrofitting due to material deterioration under extreme environmental conditions, an increase in the applied load (i.e., emerging heavier trucks in transportation structures) and the change in the functions of the structures 12–14 . Fiber‐Reinforced‐Polymer (FRP) has been considered an ideal strengthening material for improving the deformation and load carrying capacity (LCC) of HSC columns due to its advantages of being free from corrosion with high fatigue resistance and stiffness, high strength‐to‐weight ratio, less maintenance and fast and easy installation 15–19 …”

Experimental study, modeling, and reliability analysis of impact resistance of micro steel fiber‐reinforced concrete modified with nano silica

“…Mastali and Dalvand 9 studied the impact resistance, and mechanical behavior of fiber reinforced compacting concrete modified with NS and silica fume. The impact resistance is regarded as one of the critical concrete properties for applications in civil engineering Zhang et al 10 Numerous studies revealed that randomly dispersed steel fibers (SFs) could remarkably improve the concrete mechanical properties, toughness, impact resistance, post crack behavior, and fatigue properties 11–16 . For instance, Zhao et al 17 studied the combined effect of steel slag and hooked‐end SFs on the fresh and mechanical properties of self‐compacting concrete.…”

“…The impact resistance is regarded as one of the critical concrete properties for applications in civil engineering Zhang et al 10 Numerous studies revealed that randomly dispersed steel fibers (SFs) could remarkably improve the concrete mechanical properties, toughness, impact resistance, post crack behavior, and fatigue properties. [11][12][13][14][15][16] For instance, Zhao et al 17 studied the combined effect of steel slag and hooked-end SFs on the fresh and mechanical properties of self-compacting concrete. Matalkah et al 18 investigate the effect of fiber type and dosage on the mechanical and shrinkage properties of alkali-activated kaolin binder.…”

Behavior of RC columns incorporating with steel and recycled plastic fibers under eccentric load: An experimental work

“…RESULTS AND DISCUSSION4.1 | Failure patternsGenerally, based on results of many experiments[58][59][60][61][62] related RC columns, the failure modes of the columns are well understand. Figure5illustrated failure patterns of the tested columns.…”