scholarly journals Experimental Study on the Bond Performance between Fiber-Reinforced Polymer Bar and Unsaturated Polyester Resin Concrete

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Wenchao Li ◽  
Min Zhou ◽  
Fusheng Liu ◽  
Yuzhao Jiao ◽  
Qingfeng Wu
Keyword(s):  
Failure Modes ◽  
Polyester Resin ◽  
Unsaturated Polyester ◽  
Unsaturated Polyester Resin ◽  
Fiber Reinforced Polymer ◽  
Engineering Practice ◽  
Fiber Reinforced ◽  
Pull Out ◽  
Reinforced Polymer ◽  
Frp Bar

Fiber-reinforced polymer (FRP) bar-reinforced unsaturated polyester resin concrete (UPC) can solve the problem of rebar corrosion in ordinary reinforced concrete members. However, it has not been widely used in engineering practice because there have been few studies conducted on the bond behaviors of FRP bar and UPC, and the interaction mechanisms between FRP bar and UPC have not been well understood. A series of pull-out tests are conducted on FRP bar-UPC specimens to study the bond behaviors between these two materials. Parametric studies are also carried out to investigate the effects of FRP bar diameter, fiber type, type of surface treatment, concrete cover thickness, and interfacial bond length between the two. Three failure modes of the specimens are observed from pull-out tests, i.e., FRP bar pull-out, tensile failure of FRP bar, and UPC split. A new constitutive model is, therefore, proposed to predict the bond stress of FRP bar and UPC in the residual stage, and the proposed model is finally verified by test data reported in this study.

scholarly journals Experimental Analysis of Continuous Beams Made of Self-Compacting Concrete (Scc) Strengthened with Fiber Reinforced Polymer (Frp) Materials

2021 ◽  
Vol 11 (9) ◽  
pp. 4032
Author(s):  
Žarko Petrović ◽  
Bojan Milošević ◽  
Slobodan Ranković ◽  
Biljana Mladenović ◽  
Dragan Zlatkov ◽  
...  
Keyword(s):  
Experimental Analysis ◽  
Failure Modes ◽  
Fiber Reinforced Polymer ◽  
Flexural Behavior ◽  
Engineering Practice ◽  
Fiber Reinforced ◽  
Self Compacting Concrete ◽  
Near Surface ◽  
Reinforced Polymer ◽  
Continuous Beams

Strengthening of concrete structures is applied as a solution for various deterioration problems in civil engineering practice. This also refers to the structures made of self-compacting concrete (SCC), which is increasingly in use, but there is a lack of research in this field. This paper presents an experimental analysis of flexural behavior of reinforced concrete (RC) continuous beams made of SCC, strengthened with fiber reinforced polymer (FRP) materials (glass (GFRP) and carbon (CFRP) bars, CFRP laminates), by the use of near surface mounted (NSM) and externally bonded (EB) methods. Six two-span continuous beams of a total length of 3200 mm, with the span between supports of 1500 mm and 120/200 mm cross section, were subjected to short-term load and tested. The displacements of beams and the strains in concrete, steel reinforcement, FRP bars and tapes were recorded until failure under a monotonically increasing load. The ultimate load capacities of the strengthened beams were enhanced by 22% to 82% compared to the unstrengthened control beam. The ductility of beams strengthened with GFRP bars was satisfactory, while the ductility of beams strengthened with CFRP bars and tapes was very small, so the failure modes of these beams were brittle.

Analysis of influence factors on interfacial bond between BFRP bars and seawater sea-sand concrete

2020 ◽  
pp. 073168442094160
Author(s):  
Yuntao Hua ◽  
Shiping Yin ◽  
Zihan Wang
Keyword(s):  
Bond Strength ◽  
Bond Length ◽  
Failure Modes ◽  
Influence Factors ◽  
Basalt Fiber ◽  
Fiber Reinforced Polymer ◽  
Fiber Reinforced ◽  
Bond Slip ◽  
Pull Out ◽  
Reinforced Polymer

In this paper, the influences of parameters such as the bond length, surface textures of reinforcement, reinforcement type and stirrups restraint were considered. Pull-out failure, splitting failure and splitting-pullout failure modes were observed during the test. The slip at the free end always lagged behind the slip at the loading end and the bond-slip curve of ribbed basalt fiber reinforced polymer (BFRP) bars included the micro-slip stage, slip stage, descent stage, and residual stage. Reducing the bond length and using ribbed-sand coated bars were beneficial to improve the bond performance. Increasing the bond length from 2.5 d to 5 d reduced the bond strength by 49.2%. The application of ribbed-sand coated bars instead of plain bars increased the bond strength by 1202.3%. The difference in bond strength between steel bars, BFRP bars and glass fiber reinforced polymer (GFRP) bars was small and the bond strengths of the three were much greater than that of carbon fiber reinforced polymer (CFRP) bars. This was mainly attributed to the different rib forms of the bars. The application of stirrups increased the bond strength by 11.5%, which indicated that the stirrup restraints can improve the bond behavior to a certain extent. Besides, the analysis of the bond-slip curve based on the energy perspective was consistent with test results.

scholarly journals Experimental Studies on Bond Performance of BFRP Bars Reinforced Coral Aggregate Concrete

2019 ◽  
Vol 13 (1) ◽  
Author(s):  
Lei Wang ◽  
Zhaoping Song ◽  
Jin Yi ◽  
Jiayi Li ◽  
Feng Fu ◽  
...  
Keyword(s):  
Failure Modes ◽  
Fiber Reinforced Polymer ◽  
Constitutive Relationship ◽  
Fiber Reinforced ◽  
Ocean Engineering ◽  
Aggregate Concrete ◽  
Bond Slip ◽  
Bond Performance ◽  
Pull Out ◽  
Reinforced Polymer

Abstract Basalt fiber reinforced polymer (BFRP) rebars reinforced coral aggregate concrete is a new type of concrete used in ocean engineering. In order to investigate the bond performance between BFRP rebars and coral concrete, 30 pull-out tests were carried out in 10 groups with different diameters of BFRP rebars, bonding lengths and strength of the coral concrete. The results show that good bonding between BFRP rebars and coral concrete were achieved. The main failure modes can be categorized as BFRP rebars pull out destruction, splitting failure of coral concrete and BFRP rebars fracture. The bond slip ($$\tau{\text{-}}s$$ τ - s ) curves of the BFRP rebars and coral concrete were obtained during the tests. It was found to be similar to the common concrete using fiber reinforced polymer (FRP) bars. The bond-slip relation can be roughly divided into micro-slip phase, slip phase, decline phase, and the residual stress stage. The bond between BFRP rebars and coral concrete increases with the increase of the bond length and diameter of BFRP rebars, but the average bond stress will decrease. Moreover, increasing the strength of coral concrete is effective to improve the bond performance of BFRP rebars. In this paper, the continuous bond slip model (Gao et al. in J Zhengzhou Univ 23:1–5, 2002) was used to represent the $$\tau{\text{-}}s$$ τ - s constitutive relationship of BFRP rebars and coral concrete. The analysis show that the proposed model has a high degree of accuracy in representing $$\tau{\text{-}}s$$ τ - s curve of BFRP rebars and coral concrete.

Thermal effect on fiber reinforced polymer reinforced concrete slabs

2008 ◽  
Vol 35 (3) ◽  
pp. 312-320 ◽  
Author(s):  
A. Zaidi ◽  
R. Masmoudi
Keyword(s):  
Thermal Effect ◽  
Concrete Cover ◽  
Fiber Reinforced Polymer ◽  
Concrete Slabs ◽  
Fiber Reinforced ◽  
Reinforced Concrete Slabs ◽  
Reinforced Polymer ◽  
Frp Bar ◽  
Frp Bars ◽  
Concrete Interface

The difference between the transverse coefficients of thermal expansion of fiber reinforced polymer (FRP) bars and concrete generates radial pressure at the FRP bar – concrete interface, which induces tensile stresses within the concrete under temperature increase and, eventually, failure of the concrete cover if the confining action of concrete is insufficient. This paper presents the results of an experimental study to investigate the thermal effect on the behaviour of FRP bars and concrete cover, using concrete slab specimens reinforced with glass FRP bars and subjected to thermal loading from –30 to +80 °C. The experimental results show that failure of concrete cover was produced at temperatures varying between +50 and +60 °C for slabs having a ratio of concrete cover thickness to FRP bar diameter (c/db) less than or equal to 1.4. A ratio of c/db greater than or equal to 1.6 seems to be sufficient to avoid splitting failure of concrete cover for concrete slabs subjected to high temperatures up to +80 °C. Also, the first cracks appear in concrete at the FRP bar – concrete interface at temperatures around +40 °C. Comparison between experimental and analytical results in terms of thermal loads and thermal strains is presented.

scholarly journals High Mechanic Enhancement of Chopped Carbon Fiber Reinforced-Low-Density Unsaturated Polyester Resin Composite at Low Preparation Temperature with Facile Polymerization

Materials ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4273
Author(s):  
Jian Zhang ◽  
Xiaojun Wang ◽  
Xinjun Fu
Keyword(s):  
Composite Materials ◽  
Carbon Fiber ◽  
Low Temperature ◽  
Surface Defect ◽  
Polyester Resin ◽  
Unsaturated Polyester ◽  
Unsaturated Polyester Resin ◽  
Low Density ◽  
Fiber Reinforced ◽  
Preparation Temperature

Chopped carbon fiber-reinforced low-density unsaturated polyester resin (CCFR-LDUPR) composite materials with light weight and high mechanical properties were prepared at low temperature and under the synergistic action of methyl ethyl ketone peroxide (MEKP-II) and cobalt naphthenate. Optimal preparation conditions were obtained through an orthogonal experiment, which were preparation temperature at 58.0 °C, 2.00 parts per hundred of resin (phr) of NH4HCO3, 4.00 phr of chopped carbon fibers (CCFs) in a length of 6.0 mm, 1.25 phr of initiator and 0.08 phr of cobalt naphthenate. CCFR-LDUPR composite sample presented its optimal properties for which the density (ρ) was 0.58 ± 0.02 g·cm−3 and the specific compressive strength (Ps) was 53.56 ± 0.83 MPa·g−1·cm3, which is 38.9% higher than that of chopped glass fiber-reinforced low-density unsaturated polyester resin (CGFR-LDUPR) composite materials. Synergistic effects of initiator and accelerator accelerated the specific polymerization of resin in facile preparation at low temperature. Unique “dimples”, “plate microstructure” and “surface defect” fabricated the specific microstructure of the matrix of CCFR-LDUPR composite samples, which was different from that of cured unsaturated polyester resin (UPR) with “body defect” or that of CGFR-LDUPR with coexistence of “surface defect” and “body defect”.

Shear Failure Analysis of Concrete Beams Reinforced with Newly Developed GFRP Stirrups

2006 ◽  
Vol 324-325 ◽  
pp. 995-998
Author(s):  
Cheol Woo Park ◽  
Jong Sung Sim
Keyword(s):  
Failure Modes ◽  
Shear Failure ◽  
Concrete Beams ◽  
Fiber Reinforced Polymer ◽  
Experimental Program ◽  
Shear Stresses ◽  
Fiber Reinforced ◽  
Shear Span ◽  
Reinforced Polymer ◽  
A New Technique

Even though the application of fiber reinforced polymer (FRP) as a concrete reinforcement becomes more common with various advantages, one of the inherent shortcomings may include its brittleness and on-site fabrication and handling. Therefore, the shape of FRP products has been limited only to a straight bar or sheet type. This study suggests a new technique to use glass fiber reinforced polymer (GFRP) bars for the shear reinforcement in concrete beams, and investigates its applicability. The developed GFRP stirrup was used in the concrete instead of ordinary steel stirrups. The experimental program herein evaluates the effectiveness of the GFRP stirrups with respect to different shear reinforcing ratios under three different shear span-to-depth testing schemes. At the same shear reinforcing ratio, the ultimate loads of the beams were similar regardless the shear reinforcing materials. Once a major crack occurs in concrete, however, the failure modes seemed to be relatively brittle with GFRP stirrups. From the measured strains on the surface of concrete, the shear stresses sustained by the stirrups were calculated and the efficiency of the GFRP stirrups was shown to be 91% to 106% depending on the shear span-to-depth ratio.

scholarly journals Effect of Bolt-Hole Clearance on Bolted Connection Behavior for Pultruded Fiber-Reinforced Polymer Structural Plastic Members

2017 ◽  
Vol 2017 ◽  
pp. 1-12 ◽  
Author(s):  
Sang-Pyuk Woo ◽  
Sun-Hee Kim ◽  
Soon-Jong Yoon ◽  
Wonchang Choi
Keyword(s):  
Failure Modes ◽  
Fiber Reinforced Polymer ◽  
Structural Members ◽  
Fiber Reinforced ◽  
Cross Sectional ◽  
Bolted Connection ◽  
Reinforced Polymer ◽  
Connection System ◽  
Structural Plastic ◽  
Bolt Connection

Bolt-hole clearance affects the failure mode on the bolted connection system of pultruded fiber-reinforced polymer plastic (PFRP) members. The various geometric parameters, such as the shape and cross-sectional area of the structural members, commonly reported in many references were used to validate the bolt-hole clearance. This study investigates the effects of the bolt-hole clearance in single-bolt connections of PFRP structural members. Single-bolt connection tests were planned using different bolt-hole clearances (e.g., tight-fit and clearances of 0.5 mm to 3.0 mm with 0.5 mm intervals) and uniaxial tension is applied on the test specimens. Most of the specimens failed in two sequential failure modes: bearing failure occurred and the shear-out failure followed. Test results on the bolt-hole clearances are compared with results in the previous research.

Fabrication and Characterization of E-Glass Fiber Reinforced Unsaturated Polyester Resin Based Composite Materials

2019 ◽  
Vol 24 ◽  
pp. 1-7
Author(s):  
Md. Naimul Islam ◽  
Harun Ar-Rashid ◽  
Farhana Islam ◽  
Nanda Karmaker ◽  
Farjana A. Koly ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Glass Fiber ◽  
Bending Strength ◽  
Polyester Resin ◽  
Unsaturated Polyester ◽  
Glass Fibers ◽  
Tensile Modulus ◽  
Unsaturated Polyester Resin ◽  
Fiber Reinforced ◽  
Bending Modulus

E-glass fiber mat reinforced Unsaturated Polyester Resin (UPR)-based composites were fabricated by conventional hand lay-up technique. The fiber content was varied from 5 to 50% by weight. Mechanical properties (tensile and bending) of the fabricated composites were investigated. The tensile strength (TS) of the 5% and 50% fiber reinforced composites was 32 MPa and 72 MPa, respectively. Similarly, tensile modulus, bending strength and bending modulus of the composites were increased by the increase of fiber loading. Interfacial properties of the composites were investigated by scanning electron microscopy (SEM) and the results revealed that the interfacial bond between fiber and matrix was excellent. Keywords: Unsaturated Polyester Resin, Mechanical Properties, E-glass Fibers, Composites, Polymer.

Fabrication and Characterization of Banana Fiber Reinforced Unsaturated Polyester Resin Based Composites

2020 ◽  
Vol 29 ◽  
pp. 84-92
Author(s):  
Md. Sahadat Hossain ◽  
Mashrafi Bin Mobarak ◽  
Farzana Khan Rony ◽  
Sazia Sultana ◽  
Monika Mahmud ◽  
...  
Keyword(s):  
Polyester Resin ◽  
Natural Fiber ◽  
Unsaturated Polyester ◽  
Testing Machine ◽  
Unsaturated Polyester Resin ◽  
Reinforced Composites ◽  
Fiber Reinforced ◽  
Banana Fiber ◽  
Bending Modulus ◽  
Ft Ir

Concerning the importance of composite material for multi-purpose applications, an attempt has been taken to synthesize composites using natural fiber with unsaturated polyester resin. Since the use of synthetic polymer plays a key role in polluting the environment, we have used natural fiber (banana fiber) as an alternative source. Our approach dealt with the preparation of reinforced composites by hand lay-up technique using 20 % banana fiber (by weight) as reinforcing materials. Several techniques were applied to characterize synthesized composites e.g. universal testing machine (UTM), Fourier transform infrared (FT-IR) spectroscopy, and scanning electron microscopy (SEM). UTM facilitated the measurement of the tensile strength (TS), tensile modulus (TM), elongation at break (EB), bending strength (BS), and bending modulus (BM) while functional groups were confirmed by FT-IR and the morphology of the composites was investigated by SEM. Observed results revealed that the TS, TM, BS, and BM followed an increasing fashion of 100%, 53%, 75%, and 55% respectively with respect to the matrix materials. On the other hand, the EB of the composite reduced drastically by 50%. Hence, higher mechanical properties were obtained for the banana fiber reinforced composites (BFRC) than the unsaturated polyester resin (UPR) matrix.

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