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This paper conducts axial compression test of ultrahigh performance concrete- (UHPC-) filled hybrid FRP (HFRP) tubes, using the alternating hybrid technology to improve the deformation capacity of FRP tube and measure the axial compressive responses of ultimate strength, strains, and stress-strain curve of confined specimens. The test results show...
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... Consequently, the study concluded that the contribution of hybrid FRP jackets to column confinement was like that of nonhybrid jackets. Deng and Qu (2015) conducted an experimental campaign on the axial compression behavior of hybrid FRP tubes filled with ultrahigh-performance concrete. Carbon, aramid, basalt, and glass unidirectional dry fabrics were used as reinforcing materials, and epoxy resin as a matrix. ...
Hybrid fiber-reinforced polymer (FRP) composites, combining different types of fibers within a polymeric matrix, have piqued the research community’s interest due to their enhanced mechanical properties and functional performance. These materials offer optimized fiber usage, tailored failure responses, and potential for pseudoductile behavior. Furthermore, hybridization avoids catastrophic tensile failure despite the composites being composed entirely of brittle materials. Empirical evidence from previous research conducted on hybrid FRP composites for civil engineering applications suggests their potential as a promising asset to the field. This review paper collates extensive research and development work on hybrid FRP composites for civil engineering applications, providing a comprehensive summary since their inception. It covers areas including the development of reinforcing bars for reinforced concrete (RC) structures, externally bonded strengthening systems for RC structures, pultruded profiles for novel structures, and cables for long-span bridges. The paper begins with a concise overview of the influential developments that paved the way for hybrid FRP composites, followed by an in-depth discussion of their utilization in the construction sector. The paper concludes by extrapolating the potential future trajectory of hybrid FRP composites, providing insights into their future outlook.
... al. [51][52] conducted a series of studies on the combined use of the I-shaped pultruded FRP profile and an overlying UHPC slab for the application in bridges. In terms of vertical load-bearing members, numerous studies have been conducted on the UHPC columns confined by FRP sheet/tube [53][54][55][56][57][58][59][60][61]. Recently, two types of FRP-UHPC tubular permanent formwork were developed by Zeng et. ...
This paper proposes a new type of small-sized I-shaped engineered cementitious composite (ECC)/ ultra-high performance concrete (UHPC) composite beam which has the potential to be suitable for corrosive environments. The lower tensile part of the beam was made of ECC material (2/3 of the height), and the top compressive part was made of UHPC material (1/3 of the height). Inner embedded steel bars and surface-bonded basalt fiber reinforced polymer (BFRP) sheets were adopted as the reinforcing materials in combination. A total of nine I-shaped beams were designed and tested under four-point bending test. The influence of parameters such as the ratio of the embedded tensile steel bars, the top UHPC flange, and the surface bonded tensile BFRP sheet on the behavior of the beams was investigated. The results showed that the I-shaped ECC/UHPC composite beams have excellent comprehensive performance, and thanks to the ultra-high durability of the component materials, they have ultra-high durability that ordinary I-steel beams do not have and thus have broad application prospects in corrosive environments. The shear resistance capacity of the thin-walled ECC web needs to be further improved, and UHPC is recommended for the web in the follow-up study.
... al. [52,53] conducted a series of studies on the combined use of the I-shaped pultruded FRP profile and an overlying UHPC slab for the application in bridges. In terms of vertical load-bearing members, a large number of studies have been conducted on the UHPC columns confined by FRP sheet/tube [45,[54][55][56][57][58][59][60][61]. Recently, two types of FRP-UHPC tubular permanent formwork were developed by Zeng et. ...
A new type of small-sized I-shaped ultra-high-performance concrete (UHPC) beam was proposed and tested in this paper. The bottom flange of the I-beam was hybrid reinforced with an embedded steel plate and basalt fiber reinforced polymer (BFRP) sheets. The web was hybrid shear reinforced with embedded steel threaded rods and vertically surface bonded BFRP sheets. The flexural behavior was tested using the four-point loading method, the test parameters include the cross-sectional area of the steel plate, the containing or not of the threaded rods in the web, and the number of the surface bonded BFRP layer. Based on the test data, the calculation and analysis of the cracking, yielding, and ultimate loads of the UHPC beam were conducted. The results showed that the proposed new hybrid beam has excellent mechanical properties. The proposed hybrid reinforcement method can greatly increase the bearing capacity of the UHPC beam from 10.2 kN to 76.6 kN and can increase the ultimate mid-span displacement from a very small 0.52 mm to an astonishing 45.02 mm. Thanks to the ultra-high durability of BFRP and UHPC itself, it has ultra-high durability that ordinary I-steel beams do not have, which has promising application prospects in extremely corrosive environments.
... al. [51][52] conducted a series of studies on the combined use of the I-shaped pultruded FRP profile and an overlying UHPC slab for the application in bridges. In terms of vertical load-bearing members, numerous studies have been conducted on the UHPC columns confined by FRP sheet/tube [53][54][55][56][57][58][59][60][61]. Recently, two types of FRP-UHPC tubular permanent formwork were developed by Zeng et. ...
... With respect to pseudo-ductile behavior, most of research [23,28,30,31] on concrete confined with HFRP did not exhibit pseudo-ductile performance. Ribeiro [26] conducted an experimental study to investigation to the hybrid effect and pseudo-ductility of ...
This study aims to investigate the hybrid mechanism of concrete cylinders confined with different types of fiber reinforced polymer (FRP). The adoptive FRP sheets include three types of low rupture strain FRPs (carbon fiber polymer (CFRP), glass fiber polymer (GFRP) and basalt fiber polymer (BFRP)) and two types of high rupture strain FRPs (polyethylene terephthalate fiber polymer (PET-FRP) and polyethylene naphthalate fiber polymer (PEN-FRP)). More hybrid gradients are designed to exposit the hybrid mechanism of large-small rupture strain FRPs. A total of 39 FRP-confined concrete cylinders are conducted under axial compression. The tested parameters are FRP types and the number of FRP layers. The failure modes, stress-strain responses, lateral confined pressures under different axial stresses, the apparent Poisson's ratio variation and energy-dissipating capacities are analyzsed to reveal the mechanical mechanism of the specimens. The results show that the hybridization of the FRP sheets with rather different elongation capacities brings a pseudo ductility behaviour of concrete cylinders. That definitely improves the strain capacity, but the strength improvement relies on the adequate axial stiffness discrepancy between higher elongation FRP and lower elongation FRP sheets. By the hybridization, the utilization of lower elongation FRP sheets is markedly improved. The concrete cylinders confined by hybrid FRP sheets with similar elongation capacities behave like to the single FRP confined ones. Moreover, the predicted formulas are proposed and capture well the ultimate state of hybrid FRP confined concrete cylinders.
... [5,6,12,[37][38][39][40][41][42]). A number of experimental studies on SFR-CFFTs have been performed to determine the mechanical behavior of this confinement system under different type of loading such as concentric and eccentric compression [22,36,[43][44][45]. The studies focused on concentric compressive loading [22,36,45] reported that the axial stress-strain relationship of the FRP-CFFT specimens were influenced by volume fraction (V f ) and aspect ratio (A R ). ...
This study presents the results of the first experimental research on the axial compressive behavior of ultra-high strength steel (UHSS) fiber reinforced concrete-filled FRP tubes (UHSSFR-CFFT). 24 circular UHSSFR-CFFT specimens were prepared and tested under axial compression to study the influence of unconfined concrete strength and fiber type. CFFTs were manufactured with glass, carbon and basalt reinforced polymer (GFRP, CFRP and BFRP) tubes with concrete compressive strengths (f’co) ranging from 35 to 105 MPa. Axial and lateral behavior were examined closely, including variation of lateral behavior along height of specimen. The results showed that the influence of concrete compressive strength on axial compressive behavior of UHSSFR-CFFTs is dependent on fiber type. For a similar normalized lateral confining pressure of FRP jacket at ultimate (flu/f’co), axial stress enhancement ratios (k1) were observed to decrease with an increase in f’co for all three fiber types. On the other hand, the obtained axial strain enhancement ratios (k2) indicated that k2 is influenced more by flu/f’co than f’co. Comparison of the recorded values of k1 and k2 for UHSSFR-CFFT with FRP-confined plain concrete showed similar trends on the influence of (f’co) on k1, but an opposite trend was observed for k2 of BFRP-confined specimens of the current study, in which k2 increased with increasing f’co. The results showed that the shape of the lateral strain-to-axial strain curves for UHSSFR CFRP- and BFRP-confined concrete specimens were similar to those of FRP-confined plain concrete, and this relationship was not influenced noticeably by f’co. Conversely, the obtained shape of the lateral strain-to-axial strain curves for UHSSFR GFRP-confined specimens was noticeably different when compared to FRP-confined plain concrete, with this behavior influenced by f’co. Finally, the results indicated that the addition of UHSS fibers in CFRP-confined specimens did not alter the influence of f’co on strain reduction factor (kɛ) where a decrease was observed by increasing f’co. However, the converse outcome was observed for GFRP- and BFRP-confined specimens where an increase in kɛ was observed when increasing f’co.
... It is well known that the ductility and compressive strength of concrete can be significantly increased by the lateral confinement (Deng and Qu, 2015;Dundar et al., 2015;Ilki et al., 2008;Kusumawardaningsih and Hadi, 2010;Mansouri et al., 2018;Ozbakkaloglu and Vincent, 2013;Rousakis et al., 2008;Saberi et al., 2020;Smith et al., 2010;Wu and Jiang, 2013). In general, it is reported that the ductility and compressive strength of confined concrete are increased with increasing FRP confinement ratio defined as the ratio of the maximum confining pressure to the unconfined concrete strength. ...
In this study, the co-effects of steel fibers and FRP confinement on the concrete behavior under the axial compression load are investigated. Thus, the experimental tests were conducted on 18 steel fiber-reinforced concrete (SFRC) specimens confined by FRP. Moreover, 24 existing experimental test results of FRP-confined specimens tested under axial compression are gathered to compile a reliable database for developing a mathematical model. In the conducted experimental tests, the concrete strength was varied as 26 MPa and 32.5 MPa and the steel fiber content was varied as 0.0%, 1.5%, and 3%. The specimens were confined with one and two layers of glass fiber reinforced polymer (GFRP) sheet. The experimental test results show that simultaneously using the steel fibers and FRP confinement in concrete not only significantly increases the peak strength and ultimate strain of concrete but also solves the issue of sudden failure in the FRP-confined concrete. The simulations confirm that the results of the proposed model are in good agreement with those of experimental tests.
... These characteristics are owing to the ability of the steel fibres to distribute the cracks under tensile stresses (Mohammadi Hosinieh, 2014). Furthermore, HFFRP is proven to effectively improve the ultimate strain and compressive strength of UHPC specimens (Deng & Qu, 2015). The normal compressive strength acquired was about 150 MPa whereas the tensile strength is around 7 MPa (Construction and Building Materials 2013). ...
... It is ideal for strengthening a broad range of structural members such as beams, columns, slabs, and walls (Li et al., 2017) Rapid advancement of research relating to FRP jacketing to strengthen and rehabilitate concrete structures is attributed to its exceptional mechanical properties. (Deng & Qu, 2015) Most frequently used FRP confinement is through Carbon, glass and basalt fiber. Confinement through aramid and plastic fiber are also making progress in the civil industry and are likely to succeed (Lam & Teng, 2003). ...
... The stress strain curve for unconfined UHPC specimens show an almost linear relationship at the ascending stage whereas, it is curved for conventional concrete. (Deng & Qu, 2015) Figure 2.3.1 from (Deng & Qu, 2015) shows the stress strain graph for UHPC filed HFRP tubes. Which is divided into three segments; initial linear stage, transition nonlinear stage and linear hardening stage. ...
The primary aim of this research is to eventually establish three models capable of
accurately predicting the stress-strain relationship of active, passive and pseudo-active confined UHPFRC and UHPC. The research also investigates the effect of steelfiber volume ratio on the performance of UHPFRC specimens.
... In addition, because of the ultrahigh compressive strength of UHPC, the demand for improving ductility is more intense than that for improving strength, which is different from conventional concrete. Therefore, several recent studies on the axial compressive performance of FRP-confined UHPC have been conducted Mirmiran 2011, 2012;Guler 2014;Deng and Qu 2015;Wang et al. 2018;Tian et al. 2019a, b). Zohrevand and Mirmiran (2011) performed the first experimental study on the axial compressive performance of FRP-confined UHPC, and the results showed that the ductility and strength of UHPC could be significantly improved with FRP confinement. ...
This paper presents an experimental investigation and a stress-strain model for ultra-high performance concrete (UHPC)-filled fiber reinforced polymer (FRP) tubes under cyclic axial compression. Test results from 12 cyclically loaded and 18 monotonically loaded cylindrical specimens with different tube thicknesses, curing regimes, and steel fibers are presented. The influence of the tested variables on the envelope curve, plastic strain, and stress deterioration was clarified to establish a theoretical stress-strain model. Through a comprehensive assessment of well-known cyclic stress-strain model developed for FRP-confined conventional concrete, a new model for FRP-confined UHPC under cyclic axial compression is proposed based on a more rational consideration of the key characteristics of FRP-confined UHPC. Both the monotonic envelope response and the cyclic response showed good agreement between the analytic predictions based on the proposed model and the test results, confirming the capability of the proposed model to predict the cyclic axial behavior of FRP-confined UHPC.
... Given its improved ductility compared to conventional HSC, UHPC still requires adequate amounts of lateral confinement to enhance the post-peak ductility and toughness [16,17]. Fiberreinforced polymer (FRP) confinement is a well-known approach to enhance the compressive ductility of conventional concrete [18][19][20][21][22][23][24], and a number of studies on FRP-confined UHPC have been conducted to investigate this phenomenon [25][26][27][28][29][30]. Zohrevand and Mirmiran [25] conducted the first experimental investigation of the compressive performance of FRP-confined UHPC, where sixteen UHPC-filled FRP tubes were tested under monotonic axial compression. ...
