Analysis of prestressed concrete beams experimentally utilizing steel strands and CFRP bars (original) (raw)

Continuous concrete beams reinforced with CFRP bars

Proceedings of the Institution of Civil Engineers - Structures and Buildings, 2008

This paper reports the testing of three continuously and two simply supported concrete beams reinforced with carbon-fibre-reinforced polymer (CFRP) bars. The amount of CFRP reinforcement in beams tested was the main parameter investigated. A continuous concrete beam reinforced with steel bars was also tested for comparison purposes. The American Concrete Institute (ACI) 440·1R-06 equations are validated against the beam test results. Test results show that increasing the CFRP reinforcement ratio of the bottom layer of simply and continuously supported concrete beams is a key factor in enhancing the load capacity and controlling deflection. Continuous concrete beams reinforced with CFRP bars exhibited a remarkable wide crack over the middle support that significantly influenced their behaviour. The load capacity and deflection of CFRP simply supported concrete beams are reasonably predicted using the ACI 440·1R-06 equations. The potential capabilities of these equations for predictin...

Experimental Investigation of CFRP Prestressed Concrete Beams

ACI Special Publication, 2019

Synopsis: This paper presents the experimental investigation of concrete beams pre-tensioned with Carbon Fiber Reinforced Polymer (CFRP) strands. Four rectangular prestressed concrete beams were fabricated and tested under cyclic loading, and then the beams were loaded monotonically until failure. All beams were prestressed with one 0.5-in. diameter (13 mm) CFRP strand. The results showed that bond failure between CFRP strands and surrounding concrete was the main cause of early and brittle failures. Adding extra steel stirrups improved the slippage resistance capacity but was not adequate to prevent slippage at higher loads. A new technique was developed and used by anchoring the CFRP strand at the ends using a steel-tube anchorage system. The new technique prevented the slippage and improved the flexural moment capacity by 39%. An analytical computer model was created to predict the load vs. deflection responses of the beams. The behavior of beams with CFRP strands were compared to beams with steel strands using the same computer program. It was found that CFRP beams had more flexural strength but lower ductility if both beams were designed to carry the same service loads.

Durability and fatigue behavior of high-strength concrete beams prestressed with CFRP bars

2006

The need for sustainable structures has motivated an international interest in the use of fiber reinforced polymer (FRP) materials as internal reinforcement for concrete infrastructure applications. One of the contributing factors affecting the widespread use of FRP materials is the limited information regarding their long-term performance. In particular, knowledge of the long-term durability of FRPs is of prime importance. The research work presented in this paper is the result of a research collaboration between North Carolina State University (NCSU) and the University of Cambridge (UC). The research investigates the durability of concrete beams prestressed with carbon FRP (CFRP) bars and compares the results with those of companion beams prestressed with steel wires. A total of fifteen beams have been constructed and tested under different mechanical and environmental conditions. The parameters included in the program were the level of sustained stress in the bars and wires (55 and 70 percent of the ultimate bar or wire strength), the environmental exposure condition (air exposure and continuous exposure to 15 percent by mass salt water spray at 54 °C temperature), the length of time under sustained load (9 and 18 months) and the method of testing (with or without application of cyclical loading prior to static testing to failure). Test results show that the beams prestressed with steel wires did not survive the environmental exposure over 12 months whereas the beams prestressed with CFRP bars survived up to the end of the 18 month long extreme environmental exposure.

Deflection and Crack Control of Concrete Beams Prestressed by CFRP Bars

1996

Carbon fibre reinforced plastic, CFRP, reinforcement has been used for prestressing concrete bridges in North America, Europe and Japan for the last ten years. The non-corrosive characteristics, high strength to weight ratio and good fatigue properties of CFRP reinforcement could significantly increase the service life of structures. However, the high cost and low ductility of CFRP reinforcement due to its limited strain at failure could affect the use of this new material in practice. Partially prestressing of concrete members provides solution for these problems due to its advantages in reducing the cost by increasing the eccentricity of the prestressing reinforcement, and improving the deform ability . Therefore, deflection and cracking of concrete beams partially prestressed by CFRP reinforcement are of prime importance and need to be investigated. An experimental program was undertaken at the University of Manitoba to study the serviceability of concrete beams prestressed by CFRP reinforcements. The experimental program consisted of eight concrete beams prestressed by Leadline CFRP bars, produced by Mitsubishi Kasei, Japan and two concrete beams prestressed by conventional steel strands. The beams were 6.2 meter long and 330 mm in depth. The experimental program was conducted to examine the various limit states and flexural behaviour of concrete beams prestressed by CFRP bars.

Flexural behavior of preloaded reinforced concrete beams strengthened by prestressed CFRP laminates

Composite Structures

This paper aims at examining the structural behavior of perfobond strip (PBL) connectors for steelconcrete joint of hybrid girders with ultra-high performance concrete (UHPC) as grout for such connectors. Twenty-four push-out specimens fabricated according to the design used for the connectors in the steel-concrete joint in a hybrid cable-stayed bridge have been investigated. Effects of several parameters such as (i) the interface bond between perforated plate and concrete, (ii) dowels inside the holes in the plate, and (iii) volume of steel fibers in the UHPC on the behavior of PBL were discussed in depth. Experimental results indicated that the use of a 2% volume fraction of steel fibers in the UHPC, increased the average bond strength at the plate/concrete interface and the shear resistant-capacity of concrete dowel by 82% and 50%, respectively, as compared to UHPC specimens without the fibers. The concrete dowel played an important role in developing the desired loading resistant-capacity of the PBL, and about 34-41% of the overall resistance of a standard PBL embedded in UHPC were supplied by the concrete dowel surrounding transverse rebar. The source of the achieved ductility of PBL was mainly determined by the action of transverse rebars, and the ductility in the specimens having transverse rebars was about eleven times the ductility of similar specimens without the rebars. Furthermore, the experimental ultimate strength values of PBL were compared with available equations in literatures published recently, and an analytical model for PBL/UHPC was developed and appropriate parameters were derived from present data and used to provide reliable prediction of ultimate resistant-capacity of PBL in the hybrid girders' steel-concrete joints.

Seismic performance of building reinforced with CFRP bars

MATEC Web of Conferences, 2019

Over the past two decades, laboratory tests have suggested that fibre reinforced polymer (FRP) bars can replace steel bars as internal reinforcement in concrete structures, especially those are subjected to aggressive environments. FRP bars has potential for replacing steel bars as these material are corrosion-resistant and have high tensile strength, make it suitable for use as structural reinforcement. Unfortunately, the application of FRP for reinforcing structures in Indonesia is dubious. This paper aims to study the behaviour of reinforced concrete (RC) building reinforced with Carbon FRP (CFRP) and steel bars. The observed building was designed for Pekanbaru, according to SNI 2847:2013 for design of structural RC with steel bars reinforcement and the ACI 440.1R-15 for design and construction of structural RC with FRP bars. Two reinforcedconcrete moment resisting frames, extracted from 6 storey heights building with rectangular floor plan, were designed for the city of Pekanbar...

Flexural Response of CFRP-Prestressed Concrete Beams

2020

DOI:10.17605/OSF.IO/WCDZP Page 1 AbstractThis paper presents a numerical analysis investigation of the behavior of prstressed beams with carbon fiber strands (CFRP). Three dimensional finite element beam models are created on the finite element software ANSYS2013 to study the flexural response of the investigated models. The investigated models have two different types of prestressing cables, namely; steel and CFRP tendons. A parametric study was conducted to examine the effects of prestressing reinforcement ratio, concrete strength, and level of initial prestressing on the behavior of the studied prestressed concrete models. The results show that the CFRP cables can be as effective as steel cables.

Performance of steel beams strengthened with prestressed CFRP laminate

Electronic Journal of Structural Engineering

Prestressed Carbon Fibre Reinforced Polymer (CFRP) system is generally used for strengthening reinforced concrete beams where CFRP laminate can improve both the strength and serviceability behaviour of reinforced concrete beams via increasing the overall member stiffness. However, the applicability of this technique to strengthening steel structures is still lagging behind its application to concrete structures. In this study, the flexural behaviour of steel I-beams strengthened with prestressed CFRP laminate using a mechanical anchorage system is experimentally investigated. A total of nine steel beams subjected to flexural loading are tested in various conditions to evaluate the effectiveness of the proposed strengthening system. The experimental investigation confirmed that CFRP prestressing increases the ultimate load of the strengthened steel beams and moderately delays the premature debonding failure of the CFRP laminate. Even with low level of CFRP prestressing, significant e...

Flexural Strength and Ductility of CFRP Strengthened Reinforced Concrete Beams

2016

A total of fourteen beams, 100×150 mm in cross-section were tested in the laboratory over an effective span of 2000 mm. Two of them were used as reference beams. Twelve fiber reinforced concrete beams were provided with externally bonded CFRP laminates at the soffit of the beam. The variables considered included number of CFRP layers, yield strength of steel reinforcement (f y) and steel reinforcement ratio (). All the beams were tested until failure. The test results showed that the ultimate load carrying capacity increased by 56% as average by increasing of the ratio of steel reinforcement from (0.0127 to 0.0324). The deflection ductility index DDI values averaged (1.80) and (1.75) for one-layer strengthened beams and two-layer ones, respectively. The corresponding energy ductility index EDI values averaged (1.75) and (1.73), respectively. The DDI and EDI for the control beams were 4.61 and 6.24, respectively. With the exception of the control beams, all of the beams exhibited po...

Performance of preloaded CFRP-strengthened fiber reinforced concrete beams

Composite Structures, 2020

Extensive experimental investigation was conducted to evaluate the performance of fiber reinforced concrete (FRC) beams that have been externally strengthened with and without preloading in flexure using carbon fiber reinforced polymer sheets. Steel, synthetic and hybrid fibers (mix of steel and synthetic fibers) with a volume fraction of 0.5% were added to the concrete matrix to prepare 15 beams. Test results show that the addition of all fibers types improved the flexural capacity, crack initiation and propagation, stiffness, post cracking behavior, deflection and ductility of the beams. Hybrid fibers was found to improve the ductility of the FRC beams by 4 times when compared to the control specimen without fibers. Furthermore, preloading before strengthening of concrete beams without fibers led to increase of the ultimate capacity by about 120%. Preloading caused improvement in elastic stiffness of the beams by 33.4%, 23.5% 17.6 for steel, synthetic and hybrid fibers, respectively. While strengthening increased the elastic stiffness for all beams and up to 65.3%. However, for the FRC beams there was no significant improvement in the ultimate capacity from those strengthened without preloading. Applicability of ACI 440 equations to predict the capacity of fiber reinforced concrete beams was also investigated.