Abstract:This study aimed to investigate the bond properties of prestressing strands embedded in ultra-high-performance fiberreinforced concrete (UHPFRC). Toward this end, two types of prestressing strands with diameters of 12.7 and 15.2 mm were considered, along with various concrete cover depths and initial prestressing force magnitudes. The average bond strength of the strands in UHPFRC was estimated by using pullout tests, and the transfer length was evaluated based on a 95% average maximum strain method. Test resu… Show more
“…Figure 7(b) compares the experimental compressive concrete strain distribution with the FEM results. As expected, the compressive concrete strain increased from the ends of the specimen over the prestress transfer length, a behavior that was captured well by the interface bond-slip law.Figure 7.M12-H-C4-1 Mono-strand beam transfer length experiment by Oh and Kim (2000): (a) test set up, (b) experimental and FEM results of concrete strains along the beam, and UHPC transfer length experiment by Shin et al (2018): (c) test setup, (d) experimental and FEM results of UHPC strains along the beams. [All dimensions in mm].…”
Section: Description Of Finite Element Modelssupporting
confidence: 53%
“…M12-H-C4-1 Mono-strand beam transfer length experiment by Oh and Kim (2000): (a) test set up, (b) experimental and FEM results of concrete strains along the beam, and UHPC transfer length experiment by Shin et al (2018): (c) test setup, (d) experimental and FEM results of UHPC strains along the beams. [All dimensions in mm].…”
Section: Description Of Finite Element Modelsmentioning
The design of end zones to prevent severe cracking is a key requirement toward durable prestressed girders. Traditional approaches employ large amounts of steel reinforcement to attain this requirement, which may result in steel congestion. This paper investigates a hybrid girder concept that uses Ultra-High-Performance Concrete (UHPC) and Carbon Fiber Reinforced Polymer (CFRP) bars to enhance crack control and long-term durability in the end zones of prestressed girders. The objectives of this study are to quantify the UHPC zone lengths needed to restrain end zone cracks, eliminate or reduce the required amount of steel reinforcement, and investigate its replacement with CFRP bars. A finite element modeling (FEM) approach was developed for this purpose and its fidelity was validated with experimental data. The FEM results showed that UHPC zones with lengths below or equal to half of the girder depth can significantly reduce end zone cracking. CFRP bars can be added in the UHPC zones as a conservative measure to crack control, to ensure the long-term corrosion resistance of the girders.
“…Figure 7(b) compares the experimental compressive concrete strain distribution with the FEM results. As expected, the compressive concrete strain increased from the ends of the specimen over the prestress transfer length, a behavior that was captured well by the interface bond-slip law.Figure 7.M12-H-C4-1 Mono-strand beam transfer length experiment by Oh and Kim (2000): (a) test set up, (b) experimental and FEM results of concrete strains along the beam, and UHPC transfer length experiment by Shin et al (2018): (c) test setup, (d) experimental and FEM results of UHPC strains along the beams. [All dimensions in mm].…”
Section: Description Of Finite Element Modelssupporting
confidence: 53%
“…M12-H-C4-1 Mono-strand beam transfer length experiment by Oh and Kim (2000): (a) test set up, (b) experimental and FEM results of concrete strains along the beam, and UHPC transfer length experiment by Shin et al (2018): (c) test setup, (d) experimental and FEM results of UHPC strains along the beams. [All dimensions in mm].…”
Section: Description Of Finite Element Modelsmentioning
The design of end zones to prevent severe cracking is a key requirement toward durable prestressed girders. Traditional approaches employ large amounts of steel reinforcement to attain this requirement, which may result in steel congestion. This paper investigates a hybrid girder concept that uses Ultra-High-Performance Concrete (UHPC) and Carbon Fiber Reinforced Polymer (CFRP) bars to enhance crack control and long-term durability in the end zones of prestressed girders. The objectives of this study are to quantify the UHPC zone lengths needed to restrain end zone cracks, eliminate or reduce the required amount of steel reinforcement, and investigate its replacement with CFRP bars. A finite element modeling (FEM) approach was developed for this purpose and its fidelity was validated with experimental data. The FEM results showed that UHPC zones with lengths below or equal to half of the girder depth can significantly reduce end zone cracking. CFRP bars can be added in the UHPC zones as a conservative measure to crack control, to ensure the long-term corrosion resistance of the girders.
“…Furthermore, as the embedment length increases, the Poisson's ratio effect significantly diminishes the confinement effect of the surrounding concrete on the rebar. Additionally, with increased embedment length, the bond stress distribution in the bonded section tends to increase nonlinearly, leading to a reduction in bond stress [52]. In conclusion, the relationship between bonding strength and embedment length of the rebar indicates that a lower embedment length results in higher bonding strength between EGC and the rebar.…”
Section: Factors Affecting Bond Strength Of Egcmentioning
Engineered geopolymer composite (EGC) is becoming an uprising product in the civil industry as a substitute and solution for conventional geopolymer concrete (GPC) as GPC exhibits brittleness and has poor cracking resistance. In this paper, we explored high strength engineered geopolymer composite (EGC) made of polyvinyl alcohol (PVA) fibre and without coarse aggregate constituents characterised as high-performance geopolymer concrete. Varying alkaline solution to fly ash ratio (AL/FA) was investigated. Bond-slip behaviour and the mechanical properties, including compressive, tensile, and flexural strengths, were studied. PVA-EGC mix designs in this research was optimised using response surface methodology (RSM). Various parameters, including the amount of ground granulated blast slag (GGBS) and silica fume, were included in the parametric and optimisation study. Based on the RSM study, the use of quadratic studies found the responses to be well-fitted. Next, the optimised mix design was utilised for the casting of all the samples for the mechanical and bond-slip tests in this study. The main parameters of bonding behaviour include multiple embedment lengths (7 d, 10 d, 12 d and 15 d) and various sizes of rebar diameter used for pull-out tests. Moreover, the mechanical properties and bond behaviours of EGC were compared with those of conventional geopolymer concrete (GPC). The compressive strength of EGC and GPC at 28 days were designed to be similar for comparison purposes; however, EGC shows higher early compressive strength on day 1 compared to GPC. In addition, results indicate that EGC has superior mechanical properties and bond performance compared to GPC, where EGC is approximately 9 and 150% higher than GPC in terms of flexural and tensile strength, respectively. Pull-out tests showed that EGC samples exhibited higher ductility, as evidenced by the presence of multiple cracks before any exhibited failure in tension and flexure. Ductile failure modes, such as pull-out failure and pull-out splitting failure, are observed in EGC. In contrast, GPC specimens show brittle failure, such as splitting failure.
“…After release there is a transfer zone along which the strand's tensile force, and so the concrete's equilibrating compressive force, increases nonlinearly from zero at the ends to a peak at short distances inwards. Use of pullout and other tests to study the transfer zone mechanics is at the core of pretensioned concrete research [23][24][25][26][27][28][29].…”
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