Eccentrically Loaded FRP Confined Concrete with Different Wrapping Schemes

Abstract

This study presents the results of an experimental program on the comparative performance of fiberreinforced polymer (FRP) confined concrete specimens with different wrapping schemes. A total of 32 specimens in four groups were cast and tested under concentric and eccentric axial loads. All specimens were wrapped with the same amount of FRP but with different wrapping schemes, including full wrapping, partial wrapping, and nonuniform wrapping. Specimens in the first group were fully wrapped (Group F). Specimens in the second group were partially wrapped with 30 mm FRP strip spacing (Group P30). Specimens in the third group were partially wrapped with 60 mm FRP strip spacing (Group P60). Specimens in the fourth group were nonuniformly wrapped with a combination of full and partial wrapping (Group FP). Two similar specimens in each group were tested under concentric, 15 mm eccentric, 25 mm eccentric, and 40 mm eccentric axial loads. The test results indicate that fully wrapped specimens outperformed other groups of specimens under both concentric and eccentric axial loads, which were followed by nonuniformly and partially wrapped specimens. With the increase in axial load eccentricity, the performance in all groups significantly decreased. Moreover, with the increase in axial load eccentricity, the failure mode changed from FRP rupture at the compression side to extensive concrete cracking at the tension side. Equations were developed to predict the compressive strength of FRP confined concrete with different wrapping schemes. Experimental and analytical interaction (P-M) diagrams were also constructed to investigate the axial and flexural behavior of different groups of specimens.

Compressive behaviour of partially FRP confined concrete: Experimental observations and assessment of the stress-strain models

“…Due to the advantages of high strength and stiffness to weight ratios as well as superior corrosion resistance, fibre reinforced polymer (FRP) has been extensively used in recent years to improve the compressive, flexural, and shear behaviours of concrete members [1][2][3][4][5][6]. One popular application of FRP is to provide confinement to concrete columns [7][8][9][10][11][12][13][14][15]. Both experimental and analytical studies have proven that the FRP confinement can enhance the strength and ductility of concrete under compressive loadings.…”

Analytical Review on Eccentric Axial Compression Behavior of Short and Slender Circular RC Columns Strengthened Using CFRP

“…Most of the existing experimental and analytical investigations have been concerned with the behavior of FRP-confined concrete columns tested under concentric compression; however, there is only limited understanding of the behavior of FRP-confined concrete under eccentric axial compression. Therefore, many of the existing design guidelines for eccentrically loaded FRP-confined RC columns still use models derived from results of axial compression tests on plain concrete cylinders despite introducing new models that can be applied to RC columns under eccentric axial compression (e.g., Lin and Teng [ 55 ]; Wang et al [ 31 ]; Al-Nimry and Al-Rabadi [ 25 ]; El Maaddawy [ 39 ]; Csuka and Kollár [ 56 ]). The stress-strain model of Lam and Teng [ 34 ] which was adopted in most of these studies was based on a test database of 76 plain concrete cylinders of a height-to-diameter ratio ranging from 2 to 4 (i.e., D = 100–200 mm), and unconfined concrete strength ranging from 26.2 MPa to 55.2 MPa.…”

“…In reality, concrete columns are subject to eccentric loads, i.e., combined axial compression and flexural loads due to construction errors and accidental load eccentricities resulting from earthquake loads or vehicular loads. Therefore, there has been continuous research effort on the behavior of FRP-confined concrete columns under eccentric loads (e.g., [ 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 ]). Most of this research has focused on short FRP-confined circular unreinforced and reinforced concrete columns, where the effect of slenderness is negligible (e.g., Wu and Jiang [ 32 ]; Cao et al [ 33 ]).…”

Experimental Investigation of the Hybrid FRP-UHPC-Steel Double-Skin Tubular Columns under Lateral Impact Loading

“…Strengthening of existing reinforced concrete structures using fiber-reinforced polymer (FRP) composites has been widely accepted in the last three decades [ACI 440.2R (ACI 2017); GB 50608 (GB 2012); Lam and Teng 2003;Zeng et al 2018Zeng et al , 2020a. The strength, as well as the ductility of existing concrete structures, can be significantly increased by FRP strengthening (Lam and Teng 2003;Teng et al 2009;Wang et al 2016Wang et al , 2017aWang et al , 2018aWang et al , 2018c. In contrast, to develop new concrete composite members using FRP composites, such as concrete-filled FRP tubes (CFFTs) and hybrid FRP-concrete-steel double-skin tubular columns (DSTCs), is attracting more and more attention (Belzer et al 2013;Fam and Rizkalla 2001;Mohamed and Masmoudi 2010;Teng et al 2007;Wang et al 2019b;Wong et al 2008;Yu and Teng 2011;Yu et al 2010;Zhang et al 2017).…”

“…Therefore, the FRP tube can provide confinement onto the concrete and also offer shear resistance of the hybrid DSTCs (Wang et al 2015). After the novel form of hybrid DSTCs had been proposed, a large amount of investigations were conducted to understand their behaviors under different loading conditions (Idris and Ozbakkaloglu 2016;Ozbakkaloglu and Fanggi 2014;Ozbakkaloglu and Idris 2014;Ozbakkaloglu and Louk Fanggi 2015;Teng et al 2007;Wang et al 2015Wang et al , 2018aZeng et al 2020b, Zhao et al 2016. These studies proved that hybrid DSTCs exhibit superior performances under these loading conditions, which makes it a promising column type as compared to other column types.…”