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The paper presents the effect of corrosion-damaged reinforced concrete (RC) columns with circular cross section enveloped (i.e. wrapped) with externally bonded hybrid and non-hybrid fibre-reinforced polymer (FRP) reinforcement. This study consisted of 18 RC circular columns with a diameter and height of 130mm and 780 mm, respectively. These specime...
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... to the longitu- dinal steel rebars) to serve as the cathode in the accel- erated corrosion process. Figure 1 shows the dimension and internal steel reinforcement details of RC circular columns. ...
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... the protruded steel rebar could support the reinforcement cage within the formwork and to ensure the reinforcement in the vertical direction without any dislocation. As shown in Figure 1, type 304 stainless steel rebar with a diameter of 6 mm was placed at the centre of the column to act as a cathode during the accelerated corrosion activity. To facilitate the connection of steel and stainless steel [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19] //blrnas3/cenpro/ApplicationFiles/Journals/SAGE/3B2/JCMJ/Vol00000/140140/APPFile/SG-JCMJ140140.3d ...
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... the applied load increased, the width of flexural cracks significantly increased and fol- lowed by spalling of concrete on the compression face of the unconfined RC column. In the case of severe- corroded RC circular columns (see Figure 10), the observed spalling of concrete was relatively more as compared to the mild corroded and uncorroded- unconfined RC circular columns due to the effect of exposure level of corrosion activity. Eventually, all these corroded and uncorroded-unconfined RC circu- lar columns failed in buckling with crushing of con- crete. ...
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... these col- umns attained a failure of buckling with fracture of FRP reinforcement. Figure 11 shows the buckling with FRP fracture failure for non-hybrid GFRP con- fined corrosion-damaged RC column (M-1-G). No debonding of FRP reinforcement was observed in any of hybrid FRP and non-hybrid CFRP and GFRP con- fined corrosion-damaged RC circular columns. ...
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... FRP confined columns. Figure 12 shows the comparison of failure loads for uncorroded and cor- roded FRP-confined RC circular columns. From Figure 12, it is evident that FRP wrapping system enhanced the load-carrying capacity of uncorroded FRP confined RC circular columns under eccentric loading. ...
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... 12 shows the comparison of failure loads for uncorroded and cor- roded FRP-confined RC circular columns. From Figure 12, it is evident that FRP wrapping system enhanced the load-carrying capacity of uncorroded FRP confined RC circular columns under eccentric loading. The load-carrying capacity of uncorroded RC columns confined with one ply of CFRP (Ctrl-1-C), two plies of CFRP (Ctrl-2-C), one ply of GFRP (Ctrl-1-G) and two plies of GFRP (Ctrl-2-G), and hybrid FRP (Ctrl-H) reinforcement was 20%, 28%, 7%, 18% and 38% higher than the unconfined column (Ctrl), respectively. ...
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... was also proved that the load-carry- ing capacity of non-hybrid CFRP and GFRP-confined RC circular columns was increased as the number of FRP plies increased. Figure 13 shows the buckling with FRP fracture failure pattern of uncorroded FRP-con- fined RC circular columns. ...
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... the experimental test results confirm that the performance of specimen with hybrid FRP confinement (S-H) was 3% and 2% over the non-hybrid CFRP and GFRP RC circular columns (S-2-C and S-2-G), respectively. Figures 14 and 15 show the buckling with FRP fracture failure of mild and severe corroded FRP-confined RC circular columns, respectively. ...
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... sets of load against lateral and longitudinal displacement profiles of uncorroded-unconfined and FRP-confined, and corroded-unconfined and FRP- confined column specimens are shown in Figures 16(a) through (d). From the Figures, it can be generally seen that before attaining the maximum peak load, the rate of displacement was steadily increased as the applied increased at constant rate. ...
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... Figure 16(a), it was obvious that the stiffness of lateral and longitudinal displacement curves for uncorroded-unconfined RC circular columns was rela- tively higher as compared to mild and severe corroded unconfined RC circular columns. The stiffness of RC circular columns decreased as exposed to different levels of corrosion activity. ...
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... displacement profiles of uncorroded-unconfined and FRP-confined RC circular columns are shown in Figure 16(b). The lateral displacement profile Ctrl) and (c) severe corroded RC column (S-Ctrl). ...
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... lateral displacement profile Ctrl) and (c) severe corroded RC column (S-Ctrl). [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19] Figure 11. Buckling with FRP fracture failure for non-hybrid GFRP confined corrosion-damaged RC column (M-1-G). ...
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... in case of lateral dis- placement profile, the stiffness of specimen with hybrid FRP reinforcement was close to that of specimen (Ctrl-2-C) with two plies of CFRP reinforcement. From Figure 16(c) it was observed that the stiffness of mild corroded hybrid-FRP confined specimen (M-H) was slightly greater than the specimens with two plies of non-hybrid CFRP (M-2-C) and GFRP (M-2-G) reinforcement. It was generally observed that the stiff- ness of displacement curves of mild corroded FRP con- fined RC circular columns was marginally varied with respect to type of FRP, number of FRP layers and hybrid FRP reinforcement. ...
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... was generally observed that the stiff- ness of displacement curves of mild corroded FRP con- fined RC circular columns was marginally varied with respect to type of FRP, number of FRP layers and hybrid FRP reinforcement. However, for severe cor- roded FRP-confined RC circular columns (see Figure 16(d)), no significant difference in the stiffness of displacement curve was observed with different test variables due to the effect of increase in percentage of corrosion level. Moreover, the ductility of mild and severe corroded non-hybrid and hybrid FRP confined (a) S-1-C, (b) S-2-C, (c) S-1-G and (d) S-2-G. ...
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... axial and hoop strain results for uncorroded- unconfined and FRP-confined, and corrosion-damaged unconfined and FRP-confined RC circular columns are shown in Figures 17(a) through (c). The strain values of some FRP confined specimens did not record any strain measurement due to the malfunction or damages in strain gauges during the application of load. ...
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... should be noted that the designed e/h for this study was 0.1. Figures 18(a) and (b) show the moment-curvature profile at mid-height of FRP-confined RC circular col- umns. Based on the plane section assumption, the moment-curvature can be obtained using the differen- tial longitudinal strain on the tension and compression faces of mid-height section. ...
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Citations
... After that, there was a study by [11] on comparison of hybrid and non-hybrid confinement. The focus of [11] study is to assess the performance of hybrid and non-hybrid confinement on corrosion damaged RC circular column under compression. ...
... After that, there was a study by [11] on comparison of hybrid and non-hybrid confinement. The focus of [11] study is to assess the performance of hybrid and non-hybrid confinement on corrosion damaged RC circular column under compression. The FRP materials used by [11] are GFRP and CFRP with two component epoxy binder. ...
... The focus of [11] study is to assess the performance of hybrid and non-hybrid confinement on corrosion damaged RC circular column under compression. The FRP materials used by [11] are GFRP and CFRP with two component epoxy binder. The tensile strength of the materials is determined using flat coupon test, ASTM D3039 and the results are as in Table 1. ...
This study investigates the strength enhancement of Tin Slag Polymer Concrete (TSPC) under hybrid GFRP and CFRP confinement in comparison with mono GFRP and CFRP confinement on TSPC circular short column samples. Hybrid FRP confinement is prepared by wrapping TSPC with GFRP followed by CFRP both 1 layer using epoxy Sikadur 330 as matrix binders with 50 mm overlap. Compression test was performed on unconfined TSPC (TSPC-UC), TSPC with GFRP confinement (TSPC-GF), TSPC with CFRP confinement (TSPC-CF) and TSPC with hybrid FRP confinement (TSPC-HB) with 1mm/ min loading rate. The test results have revealed that the ultimate strengths are 59.19 MPa (TSPC-UC), 85.54 MPa (TSPC-GF), 108.77 MPa (TSPC-CF) and 124.59 MPa (TSPC-HB). The corresponding compressive strain measured at ultimate compressive strength is 0.0300 (TSPC-UC), 0.0453 (TSPC-GF), 0.0398 (TSPC-CF) and 0.0588 (TSPC-HB). Stress versus strain curve has shown that compared to TSPC-UC, externally strengthen sample with GFRP, CFRP and Hybrid FRP have enhanced TSPC strength with slight different behavior. TSPC-GF has less strength enhancement with larger strain while TSPC-CF provide larger strength enhancement but with lower strain. However, TSPC-HB has shown the highest strength enhancement with larger strain benefit from combined GFRP and CFRP properties. Failure mode of hybrid FRP confinement on TSPC (TSPC-HB) has shown combination of both FRP components failure mode (TSPC-GF and TSPC-CF) as in rupture pattern and delamination. The results of this study has provide findings on the effect of hybrid FRP confinement on TSPC circular column sample in close expectation based on literatures.
... The matrices or polymers used are mostly of the thermosetting type; i.e., epoxy resin [16][17][18]. The mechanical properties of FRPs depend on the type of fiber/resin matrix used, the orientation of the fibers, the fiber volume fraction, etc. [19][20][21][22][23][24][25]. FRP composites have been successfully used for the repair and strengthening of defective reinforced concrete and prestressed concrete members [26][27][28][29][30][31]. ...
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An experimental study was performed to investigate the effect of seawater exposure on the mechanical behavior of concrete columns reinforced longitudinally with glass fiber reinforced polymer (CCR-GFRP) bars. Numerous salt crystals emerged and slight exfoliation was observed after the surfaces of the columns were immersed in seawater for 120 days. The CCR-GFRP failed in either the axial compressive failure or split-crack failure mode. Furthermore, the probability of split-crack failure gradually increased with the duration of seawater exposure. In general, the carrying capacity of the CCR-GFRP initially increased and then decreased as the seawater exposure progressed. The strains of the surface concrete and inner glass fiber reinforced polymer bars continuously increased, but the strain of the glass fiber reinforced polymer bars and probability of the variability of the strain were less than those of the surface concrete. In addition, the bonding between the glass fiber reinforced polymer bars and concrete gradually decreased with increasing diameter of the glass fiber reinforced polymer bars. As the exposure period increased, the bonding between the glass fiber reinforced polymer bars of the same concrete columns weakened significantly.
The behavior of eccentrically loaded fiber reinforced polymer (FRP) partially wrapped reinforced concrete (RC) columns under combined environmental erosion was investigated in this paper. Circular RC columns were firstly subjected to chloride erosion where the target corrosion degree (0, 10 %, and 20 %) is obtained with externally applied current. This was then followed by partially strengthening with 2-ply of glass fiber reinforced polymer (GFRP) strips as well as 50 freeze–thaw cycles. Series of eccentric compression tests were conducted with ranging eccentricities of 0, 5 mm, 10 mm, and 15 mm. For comparison, the carbon fiber reinforced polymer (CFRP) partially strengthened columns with the corrosion degree of 10 % and subjected to 50 freeze–thaw cycles were also eccentrically loaded with an eccentricity of 10 mm. Results showed that with increasing corrosion degree, the bearing capacity of GFRP strengthened column showed a 2-stage behavior (firstly increased and then decreased), which may be caused by the confinement reduction of FRP on columns due to severe environmental erosion. Under small eccentric loading, The CFRP strengthened RC columns showed better compressive behavior than that of GFRP strengthened RC columns. Based on the stress–strain relationship of constituent materials, a simplified analytical model considered the effects of chloride and freeze–thaw erosion was put forward to predict the bearing capacity of FRP partially wrapped RC column under eccentric loading.
Over the past few years, there has been a rise in the use of Stay-In-Place (SIP) structural formworks made of fibre reinforced polymer (FRP). This study investigates the performance of decks made of FRP SIP structural formworks with an improved configuration using conventional and ultra-high performance concrete under static loadings. The proposed new composite deck consisted of a glass fibre reinforced polymer plate stiffened with Y-shape ribs for resisting tensile and shear stresses while reinforcements was placed on the compressive side of the deck. The new composite deck was compared with conventional reinforced concrete solid decks and a composite deck consisting of square hollow section (SHS) stiffeners. Results showed that the deck made of Y-shape stiffeners failed in punching shear, and the use of Y-shape stiffeners significantly enhanced the ultimate strength and shear capacity of the proposed deck. It was also concluded that the voids in the concrete deck with SHS stiffeners resulted in lightweight structures but had a negative influence on the ultimate strength of the deck cast on FRP SIP formwork. Increasing the concrete strength from 34 MPa to 140 MPa resulted in a 71% enhancement in the maximum load-carrying capacity but did not considerably influence their stiffness.
