scholarly journals The effect of different levels of pre-damage loading on the strength and structural behavior of CFRP strengthened R.C. beams: Experimental and analytical investigation

PLoS ONE ◽  
2021 ◽  
Vol 16 (12) ◽  
pp. e0261290
Author(s):  
Brwa Hamah Saeed Hamah-Ali ◽  
Mohamed Raouf Abdul Qadir
Keyword(s):  
Load Capacity ◽  
Fiber Reinforced Polymer ◽  
Fiber Reinforced ◽  
Initial Stiffness ◽  
Design Guideline ◽  
Control Beam ◽  
Damage Level ◽  
Reinforced Polymer ◽  
Steel Bars ◽  
Different Levels

In order to investigate the effect of pre-loading damage on the structural performance of Carbon Fiber Reinforced Polymer (CFRP) strengthened Reinforced Concrete (R.C.) beams, experimental and Finite Element Modelling (FEM) investigation was carried out on six R.C. beams. Five of the R.C. beams were damaged up to different levels of strain in the main steel bars before Flexure CFRP strengthening. One of the R.C. beams loaded up to failure and was kept as a control beam for comparison. The experimental results showed that the failure mode of the CFRP strengthened specimen was controlled by CFRP debonding followed by concrete crushing; however, the control beam failed in concrete crushing after yielding the steel bars, which is a ductile failure. The CFRP sheet increases the strength and initial stiffness of the R.C. beams and reduces ductility and toughness. Also, CFRP application increases the first crack and yielding steel bars load by 87.4% and 34.4%, respectively. Furthermore, the pre-damage level does not influence the strength and ductility of the strengthened R.C. beams except for the highest damage levels, which experienced a slight decrease in load capacity and ductility. However, the initial stiffness decreases with increasing pre-damage levels by 40%. Design guideline ACI 440.2R (2004) predicts the ultimate load capacity marvelously for externally bonded Fiber-Reinforced Polymer (FRP) beams compared to the experimental maximum load capacity. The excellent agreement between experimental and FEM results indicates that the constitutive models used for concrete and reinforcement and the cohesive interface model can well capture fracture behavior. However, The FEM analysis predicts the beam to be slightly stiffer and more robust, probably because of the assumed perfect bond between concrete and reinforcement. The developed FEM can be used for further parametric study.

Restoring Initially Cracked Reinforced Concrete Beams utilizing Carbon Fiber Reinforced Polymer Strips

2019 ◽  
Vol 7 (1) ◽  
pp. 30-34
Author(s):  
A. Ajwad ◽  
U. Ilyas ◽  
N. Khadim ◽  
Abdullah ◽  
M.U. Rashid ◽  
...  
Keyword(s):  
Carbon Fiber ◽  
Concrete Beams ◽  
Fiber Reinforced Polymer ◽  
Carbon Fiber Reinforced Polymer ◽  
Fiber Reinforced ◽  
Loading Test ◽  
Control Beam ◽  
Reinforced Polymer ◽  
Cfrp Sheet ◽  
Carbon Fiber Reinforced

Carbon fiber reinforced polymer (CFRP) strips are widely used all over the globe as a repair and strengthening material for concrete elements. This paper looks at comparison of numerous methods to rehabilitate concrete beams with the use of CFRP sheet strips. This research work consists of 4 under-reinforced, properly cured RCC beams under two point loading test. One beam was loaded till failure, which was considered the control beam for comparison. Other 3 beams were load till the appearance of initial crack, which normally occurred at third-quarters of failure load and then repaired with different ratios and design of CFRP sheet strips. Afterwards, the repaired beams were loaded again till failure and the results were compared with control beam. Deflections and ultimate load were noted for all concrete beams. It was found out the use of CFRP sheet strips did increase the maximum load bearing capacity of cracked beams, although their behavior was more brittle as compared with control beam.

Prior and post peaks compressive behavior of concrete-filled double-skin tubular columns with BFRP-punched-in outer steel and BFRP-circular inner steel

2020 ◽  
Vol 23 (13) ◽  
pp. 2911-2927
Author(s):  
Yung William Sasy Chan ◽  
Zhi Zhou ◽  
Zhenzhen Wang ◽  
Jinping Ou
Keyword(s):  
Load Capacity ◽  
High Energy ◽  
Fiber Reinforced Polymer ◽  
Confined Concrete ◽  
Peak Performance ◽  
Design Parameters ◽  
Fiber Reinforced ◽  
Tubular Columns ◽  
Reinforced Polymer ◽  
Double Skin

Fiber-reinforced polymer composites have been widely used to design fiber-reinforced polymer–based confined concrete columns with potential benefits. However, it is critical to design a column with sufficient post-peak performance that can prevent its collapse at the rupture of the fiber-reinforced polymer tube. This article presents the experimental results on the prior and post peaks behavior of concrete-filled double-skin tubular columns with basalt fiber-reinforced polymer (BFRP)–punched-in outer steel and BFRP-circular inner steel (BFST-DSTCs). Twenty-two specimens were tested under axial compression to investigate the effects of design parameters on the behavior of the BFST-DSTC. The outcomes reveal that the BFST-DSTC exhibits the best performance in terms of load capacity, confinement ratio, failure and damage mechanisms, and ductility in prior and post peaks. The inner fiber-reinforced polymer jacket delays the buckling of the inner tube. The punched-in patterns of the outer steel improve the confinement effectiveness of the fiber-reinforced polymer jacket. The BFST-DSTC displays a good post-peak performance with high-energy dissipation capacity that prevents the concerned structure from collapse after the fiber-reinforced polymer jacket rupture. Finally, a new confinement model is proposed to predict the ultimate point of the confined concrete.

scholarly journals PERBAIKAN KEKUATAN DAN DAKTILITAS BALOK BETON BERTULANG MENGGUNAKAN GLASS FIBER REINFORCED POLYMER (GFRP) STRIPS

2017 ◽  
Author(s):  
Parmo
Keyword(s):  
Glass Fiber ◽  
Load Capacity ◽  
Fiber Reinforced Polymer ◽  
Fiber Reinforced ◽  
Glass Fiber Reinforced Polymer ◽  
Tectonic Zone ◽  
Displacement Ductility ◽  
Highly Active ◽  
Reinforced Polymer ◽  
Glass Fiber Reinforced

Wheres Indonesia is a highly active tectonic zone that is prone to earthquakes. Important issue following the earthquake was retrofit structures to improvement strength and ductility structure. With the advancement of technology today has developed new innovations such as the use of material GFRP (Glass Fiber Reinforced Polymer) for external confinement structure. From the results obtained by the experimental of load capacity increased by 20% for C-2 (retrofit beam with GFRP strengthened 1 layer) compared B-1 (original beam). Retrofit beam with GFRP is added ductility as shown by the increase in displacement ductility 4% each for B-1 and B-2.

Flexural behavior of reinforced concrete beams strengthened by carbon fiber reinforced polymer using different strengthening techniques

2021 ◽  
pp. 136943322110499
Author(s):  
Riyam J Abed ◽  
Mohammed A Mashrei ◽  
Ali A Sultan
Keyword(s):  
Reinforced Concrete ◽  
Carbon Fiber ◽  
Fiber Reinforced Polymer ◽  
Carbon Fiber Reinforced Polymer ◽  
Rc Beams ◽  
Fiber Reinforced ◽  
Control Beam ◽  
Reinforced Polymer ◽  
Externally Bonded ◽  
Carbon Fiber Reinforced

The externally bonded reinforcement on grooves (EBROG) method is increasingly recognized as an alternative strengthening method that can overcome the debonding problem. This study aims to experimentally investigate the effectiveness of EBROG as compared to the conventional externally bonded reinforcement (EBR) method in strengthening reinforced concrete (RC) beams. Twelve RC beams have been tested under four point load bending. One of these beams has been designated as a reference beam, seven beams have been strengthened with carbon fiber reinforced polymer (CFRP) sheets, and four beams have been strengthened with CFRP laminates using EBROG or EBR methods. The effect of CFRP type, number of layers, as well as the type of strengthening methods on the flexural performance have been also investigated. The load, deflection, stiffness, and failure modes were recorded and discussed intensively. Overall, test results indicated that the flexural strength and stiffness of the strengthened specimens using EBR or EBROG methods increased compared to the control beam, where the increase in the load carrying capacity of beams strengthened using the EBR method ranged between 24.8 and 48.2% and by the EBROG method ranged between 31.7 and 76.7% of the control beam. The most interesting result obtained is that the failure mode of beams has been changed from debonding of CFRP material to rupture of CFRP in some samples strengthened by EBROG, which demonstrates the superior behavior of this strengthening technique as compared to the traditional strengthening using EBR.

Contribution of longitudinal glass fiber-reinforced polymer bars in concrete cylinders under axial compression

2018 ◽  
Vol 45 (6) ◽  
pp. 458-468 ◽  
Author(s):  
Brandon Fillmore ◽  
Pedram Sadeghian
Keyword(s):  
Elastic Modulus ◽  
Glass Fiber ◽  
Fiber Reinforced Polymer ◽  
Fiber Reinforced ◽  
Glass Fiber Reinforced Polymer ◽  
Gfrp Bars ◽  
Reinforced Polymer ◽  
Glass Fiber Reinforced ◽  
Steel Bars ◽  
Concrete Cylinders

Contribution of longitudinal glass fiber-reinforced polymer (GFRP) bars in concrete columns under compression has been ignored by current design guidelines. This paper challenges this convention by testing 21 concrete cylinders (150 mm × 300 mm) reinforced with longitudinal GFRP and steel bars in compression. It was observed that GFRP bars could sustain high level of compressive strains long after the peak load of the specimens without any premature crushing. The results of a new coupon test method showed that the elastic modulus of GFRP bars in compression is slightly higher than that of in tension, however the compressive strength was obtained 67% of tensile strength. An analytical model was successfully implemented to predict the axial capacity of the tests specimens and it was found that the contribution of the bars in the load capacity of the specimens was within 4.5–18.4% proportional to the bars reinforcement ratio normalized to the elastic modulus of steel bars.

Effect of high temperature on structural response of reinforced concrete circular columns strengthened with fiber reinforced polymer composites

2016 ◽  
Vol 51 (3) ◽  
pp. 333-355 ◽  
Author(s):  
Hussein Elsanadedy ◽  
Tarek Almusallam ◽  
Yousef Al-Salloum ◽  
Rizwan Iqbal
Keyword(s):  
Reinforced Concrete ◽  
High Temperature ◽  
Elevated Temperature ◽  
Load Capacity ◽  
Single Layer ◽  
Fiber Reinforced Polymer ◽  
Insulation Material ◽  
Fiber Reinforced ◽  
Strength Reduction Factor ◽  
Reinforced Polymer

This research investigates the effect of elevated temperature on behavior of reinforced concrete (RC) circular columns strengthened with different fiber reinforced polymer (FRP) systems. For this purpose, 32 column specimens were prepared. The test matrix comprised: 14 unstrengthened columns, 14 columns strengthened with a single layer of CFRP sheet, and 4 specimens strengthened with a single layer of GFRP sheet. Out of the 14 CFRP-wrapped specimens, 4 columns were thermally insulated with commercially available fire-protection mortar. In addition to control specimens at room temperature, some other columns were subjected to high temperature regimes of 100℃, 200℃, 300℃, 400℃, 500℃, and 800℃ for a period of 3 h. After cooling down, the columns were tested under axial compression until failure. It was indicated that exposure to elevated temperature adversely affected the residual strength, stiffness, and axial/lateral stress–strain response of unstrengthened columns. FRP composites were found effective in enhancing the axial load capacity of exposed columns provided that the temperature at the FRP level does not exceed the decomposition limit of the epoxy resin. The degradation in strength and stiffness was higher in CFRP-strengthened columns compared with GFRP-strengthened columns when exposed to the same temperature level. The used insulation material was found efficient in preventing heat induced damage to CFRP-strengthened columns up to temperature of 800℃ for 3 h duration. Besides this study, the experimental data of 48 uninsulated FRP-strengthened circular concrete specimens subjected to different heating regimes were collected from the literature. The dataset of 55 uninsulated FRP-strengthened specimens was then employed to evaluate the ACI 440.2R-08 model used for assessing compressive strength of FRP-confined concrete. This model was found non-conservative for 48.6% of the data and thus it was revised by the inclusion of an FRP strength reduction factor due to heating, which can be utilized in the design of FRP-strengthened RC columns exposed to elevated temperature.

Flexural Behaviour of Reinforced Concrete Beam with Glass Fiber Reinforced Polymer (GFRP) Bar Strengthened with Carbon Fiber Reinforced Polymer (CFRP) Plate

2014 ◽  
Vol 1051 ◽  
pp. 748-751 ◽  
Author(s):  
Norhafizah Salleh ◽  
Abdul Rahman Mohd Sam ◽  
Jamaludin Mohd Yatim ◽  
Mohd. Firdaus bin Osman
Keyword(s):  
Reinforced Concrete ◽  
Concrete Beam ◽  
Reinforced Concrete Beam ◽  
Fiber Reinforced Polymer ◽  
Fiber Reinforced ◽  
Gfrp Bars ◽  
Reinforced Polymer ◽  
Cfrp Plate ◽  
Glass Fiber Reinforced ◽  
Steel Bars

The use of glass-fiber-reinforced polymer (GFRP) bar to replace steel reinforcement in concrete structures is a relatively a new technique. The GFRP bars possess mechanical properties different from steel bars, including high tensile strength combined with low elastic modulus and linear stress–strain relationship up to failure. Therefore, design procedures and process should account for these properties. This paper presents the experimental work on the flexural behavior of concrete beam reinforced with GFRP bars and strengthen with CFRP plate. A total of ten reinforced concrete beams reinforced with either steel and GFRP bars were cast and tested under four point loads. Eight concrete beams (200x250x2800mm) were reinforced with 13mm diameter GFRP bars together with strengthening using CFRP plate and two control beams reinforced with 12mm diameter steel bars were tested. The experimental results show that although the stiffness of the beams reduced but the ultimate load of the GFRP reinforced concrete beam is bigger than steel reinforced beam. It was also found that strengthening using CFRP plate will further enhanced the flexural performance of the beams with GFRP bars.

scholarly journals Optimization of Fiber-Reinforced Polymer Bars for Reinforced Concrete Column Using Nonlinear Finite Element Algorithms

Algorithms ◽  
2021 ◽  
Vol 15 (1) ◽  
pp. 12
Author(s):  
Sajjad Sayyar Roudsari ◽  
Liviu Marian Ungureanu ◽  
Soheil Soroushnia ◽  
Taher Abu-Lebdeh ◽  
Florian Ion Tiberiu Petrescu
Keyword(s):  
Finite Element ◽  
Reinforced Concrete ◽  
Optimization Technique ◽  
Fiber Reinforced Polymer ◽  
Plastic Behavior ◽  
Fiber Reinforced ◽  
Rc Columns ◽  
Gfrp Bars ◽  
Reinforced Polymer ◽  
Steel Bars

The ductility and strength of reinforced concrete (RC) columns could be noticeably improved by replacing steel bars with polymeric bars. Despite the previous research on RC columns, most of those studies focused only on the lateral load capacity of this structural member and were mainly costly experimental studies. However, this paper is concentrated on the previously occurred damages to the reinforced columns in the previous earthquakes. Subsequently, finite element analysis has been performed to examine 24 models including the various shapes of RC columns. In employing the plastic behavior of steel, carbon fiber-reinforced polymer (CFRP), and glass fiber reinforced polymer (GFRP) bars, the bilinear hardening has been considered. To capture both compressive and tensile behavior of the concrete, the concrete damage plasticity model has been implemented. Furthermore, the optimization technique is used for CFRP models to compare with other models. In this paper, the parameters of energy, seismic factor, stiffness, and ductility have been computed using the method proposed by the authors. This suggested method is considered to compare the results from each parameter. Finite element results of steel bars are compared with carbon and glass models. The results show the stiffness of models is improved by CFRP bars, while the energy absorption and ductility factor are enhanced with steel bars. Moreover, GFRP bars can enhance the seismic factor. The reduction of column stiffness to almost half would occur in some rectangular cross-section columns.

Sign in / Sign up

Export Citation Format

Share Document