Hollow concrete columns: Review of structural behavior and new designs using GFRP reinforcement

Abstract

Hollow concrete columns (HCCs) reinforced with steel bars have been employed extensively for bridge piers, ground piles, and utility poles because they use fewer materials and offer higher structural efficiency compared to solid concrete columns with the same concrete area. Many experimental studies have been conducted to investigate the behavior of HCCs under different loading conditions and found that the structural performance of HCCs is critically affected by many design parameters. If not designed properly, HCCs exhibit brittle failure behavior, due to longitudinal bars buckling or the concrete wall failing in shear. In addition, the corrosion of steel bars has become an issue in reinforced-concrete structures. Therefore, this paper critically reviews the different design parameters that affect the performance of HCCs and identifies new opportunities for the safe design and effective use of this construction system. Moreover, the use of GFRP bars as reinforcement in hollow concrete columns is explored with the aim of developing a non-corroding and structurally reliable construction system.

Novel testing and characterization of GFRP bars in compression

“…Three high-modulus (Grade III) GFRP bars with a nominal diameter of 9.5, 15.9, and 19.1 mm were considered in this study (see Figure 1). High-modulus GFRP bars were selected due to their effectiveness as longitudinal reinforcement and significant load contribution in concrete columns [2][3][4]. The bars contain glass fibres which were impregnated with vinyl-ester resin using pultrusion process.…”

“…Glass Fibre Reinforced Polymer (GFRP) bars have been an effective alternative replacement to steel bars as internal reinforcement for concrete structures exposed to harsh environments due to their high strength and non-corrosive properties [1]. Investigation on concrete structures longitudinally and transversely reinforced with GFRP bars showed satisfactory performance in bending and shear [2][3][4][5][6]. Moreover, many experimental studies were conducted to characterise the mechanical [7][8][9][10][11][12][13], physical [14], chemical [15][16][17], thermal [8,11,18] and durability properties [10][11] of this type of reinforcements.…”

“…In recent years, there is an increased interest in the use of GFRP bars as longitudinal reinforcement for concrete columns. A number of studies have shown the effectiveness of using GFRP bars for solid and hollow concrete columns [2][3][4][31][32][33][34]. These studies emphasised the linear elastic response until failure of the GFRP bars as internal reinforcement in concrete columns.…”

“…Moreover, Maranan et al [2] stated that the compressive strength of 15.9 mm diameter GFRP bar is only 51.7% of its tensile strength with an equal elastic modulus, and will fail by buckling when the spacing between lateral spirals is 200 mm or more. Furthermore, AlAjarmeh et al [3] investigated the compressive behaviour of the 12.7 mm, 15.9 mm, and 19.1 mm diameter GFRP bars in concrete columns with a spiral spacing of 100 mm. Consistent with Maranan et al [2], all GFRP bars failed by crushing with the lower spiral spacing.…”

Performance Assessment of the Post-Tensioned Anchorage Zone Using High-Strength Concrete Considering Confinement Effect

“…Spiral reinforcement gives the main confinement effect; this means that spiral reinforcement gives a much larger confining performance than lateral reinforcements. This is easily confirmed from the study of columns; the confinement effect by the spiral reinforcement is very important [ 17 ]. However, secondary (small confinement effect from lateral reinforcements) confining cannot be ignored that the secondary confining also helps to increase the bearing tolerance [ 18 ].…”