• Proceedings of the Korea Concrete Institute Conference
• /
• 2009.05a
• /
• pp.509-510
• /
• 2009

In strengthening reinforced concrete beams using fiber reinforced polymer sheets, brittle structural failures occur due to the linear stress-strain relationship of the fibers. Hybrid fiber reinforced polymer sheets using two different types of fibers were investigated in this study

• Proceedings of the Korea Concrete Institute Conference
• /
• 2005.05a
• /
• pp.399-402
• /
• 2005

This paper presents shear strength of concrete beam using FRP bars for flexure and shear reinforcements. Generally, the material properties of FRP bar are different from steel reinforcement. So, the shear strength correction factor is proposed through the experimental results.

• Structural Engineering and Mechanics
• /
• v.50 no.6
• /
• pp.709-722
• /
• 2014

Ultra-High Performance Concrete (UHPC) is an innovative new material that, in comparison to conventional concretes, has high compressive strength and excellent ductility properties achieved through the addition of randomly dispersed short fibers to the concrete mix. This study presents the results of an experimental investigation on the behavior of axially loaded UHPC short circular columns wrapped with Carbon-FRP (CFRP), Glass-FRP (GFRP), and Aramid-FRP (AFRP) sheets. Six plain and 36 different types of FRP-wrapped UHPC columns with a diameter of 100 mm and a length of 200 mm were tested under monotonic axial compression. To predict the ultimate strength of the FRP-wrapped UHPC columns, a simple confinement model is presented and compared with four selected confinement models from the literature that have been developed for low and normal strength concrete columns. The results show that the FRP sheets can significantly enhance the ultimate strength and strain capacity of the UHPC columns. The average greatest increase in the ultimate strength and strain for the CFRP- and GFRP-wrapped UHPC columns was 48% and 128%, respectively, compared to that of their unconfined counterparts. All the selected confinement models overestimated the ultimate strength of the FRP-wrapped UHPC columns.

• Computers and Concrete
• /
• v.32 no.1
• /
• pp.1-13
• /
• 2023

This paper discusses a framework for predicting the flexural strength of prestressed and non-prestressed FRP reinforced T-shaped concrete beams using soft computing techniques. An analysis of 83 tests performed on T-beams of varying widths has been conducted for this purpose with different widths of compressive face, beam depth, compressive strength of concrete, area of prestressed and non-prestressed FRP bars, elasticity modulus of prestressed and non-prestressed FRP bars, and the ultimate tensile strength of prestressed and non-prestressed FRP bars. By analyzing the data using two soft computing techniques, named artificial neural networks (ANN) and gene expression programming (GEP), the fundamental parameters affecting the flexural performance of prestressed and non-prestressed FRP reinforced T-shaped beams were identified. The results showed that although the proposed ANN model outperformed the GEP model with higher values of R and lower error values, the closed-form equation of the GEP model can provide a simple way to predict the effect of input parameters on flexural strength as the output. The sensitivity analysis results revealed the most influential input parameters in ANN and GEP models are respectively the beam depth and elasticity modulus of FRP bars.

• Journal of Korean Association for Spatial Structures
• /
• v.4 no.3 s.13
• /
• pp.85-91
• /
• 2004

Rehabilitations of reinforced concrete(RC) structures using advanced fibre-reinfored plastic(FRP) composites has become very popular in last few years. Typical method of strengthening strategy using FRP composite is bonding the CFRP plate or sheet on the surface of existing concrete structures. Many researches, however, have shown that bonding FRP plate or sheet on the surface of concrete has tendancy to debond prematurely induced by stress concentrations at the end of the plate. In order for overcoming the premature failure, the filling-up method which places FRP-rod into the existing concrete sawing groove has been developed. Through filling-up test results, aims of this research is to investigate the efficiencies of the filling-up method and is to determine the availabilities of traditional flexural theories that has provided all over the world.

• Journal of The Korean Society of Agricultural Engineers
• /
• v.46 no.3
• /
• pp.73-81
• /
• 2004

FRP reinforcing bars(rebars) are produced through a variety of manufacturing process includes pultrusion, and filament winding and braiding etc. Each manufacturing method produces a different surface condition of FRP rebar. The surface properties of FRP rebar is an important property for mechanical bond with concrete. Current methods of providing surface deformation to FRP rebars include helical wrapping, surfaces and coating and rib molding. The problem with the helical wrapping method is that it can not provide enough surface deformation for good bond and it can be easily sheard off from the FRP rebars. Sand coating and rib molding provide surface deformation only to the outer FRP skins. Therefore, FRP rebar has about 60% of bond strength of steel rebar. The main objective was to evaluate the bond properties of FRP rebar after environmental exposure. Five types of FRP rebar includes CFRP ISO, GFRP Aslan, AFRP Technora CFRP(Korea), and GFRP(Korea) rebars performed direct bond tests. Also, FRP rebar bond specimens were subjected to exposure conditions including alkaline solution, acid solution, salt solution and deionized water etc. According to bond test results, CFRP(Korea) and CFRP(Korea) rebars were found to have better bond strength with concrete than previous FRP rebars. Also, FRP(Korea) rebar had more than about 70% in bond strength of steel rebar.

• International Journal of Concrete Structures and Materials
• /
• v.8 no.1
• /
• pp.27-41
• /
• 2014

The use of carbon fibers (CF) and glass fibers (GF) were combined to strengthen concrete flexural members. In this study, data of tensile tests of 94 hybrid carbon-glass FRP sheets and 47 carbon and GF rovings or sheets were thoroughly investigated in terms of tensile behavior. Based on comparisons between the rule of mixtures and test data, positive hybrid effects were identified for various (GF/CF) ratios. Unlike the rule of mixtures, the hybrid sheets with relatively low (GF/CF) ratios also produced pseudo-ductility. From the calibrated results obtained from experiments, a new analytical model for the stress-strain relationship of hybrid FRP sheets was proposed. Finally, the hybrid effects were verified by structural tests of concrete members strengthened with hybrid FRP sheets and either carbon or glass FRP sheets.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2006.05a
• /
• pp.38-41
• /
• 2006

Wheel load fatigue experiment is carried out on a FRP-concrete composite deck. In FRP-concrete composite deck, FRP plays a role of a main tensile member as well as a permanent formwork and concrete plays a role of a main compressive member. Wheel load fatigue experiment, which shows more realistic behavior than pulsating fatigue experiment, is selected as a fatigue performance evaluation method. Until 1,000,000 cycles of loadings, load resistant performance is maintained without any loss, while residual deflection is increased.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2010.05a
• /
• pp.435-436
• /
• 2010

This research presents two important factors; first, the advanced design equation of effective bonding length at the interface between concrete and FRP materials is proposed when different bonding materials are applied and secondly maximum bonding strength between concrete-FRP bonding surface is evaluated under Freeze-thaw cycles.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2006.11a
• /
• pp.133-136
• /
• 2006

The main purpose of this study is to develop a Sprayed FRP repair and strengthening method, which is a new technique for strengthening the existing concrete structures by mixing carbon or glass shot fibers and the epoxy or vinyl ester resins with high-speed compressed air in open air and randomly spraying the mixture onto the concrete surface. At present, the Sprayed FRP repair and strengthening method using the epoxy resin has not been fully discussed. In this study, a series of experiments are carried out to evaluate the strengthening effects of the flexural and shear concret beams strengthened with the Sprayed FRP method. The results revealed that the strengthening effects of the flexural and shear specimens are similar, compared to those of the FRP sheet.