scholarly journals Strength Degradation in Curved FRP bars as Concrete Reinforcement

2020 ◽  
Author(s):  
Thanongsak Imjai ◽  
Reyes Garcia ◽  
Maurizio Guadagnini ◽  
Kypros Pilakoutas
Keyword(s):  
Tensile Strength ◽  
Structural Damage ◽  
Mechanical Performance ◽  
Failure Criteria ◽  
Strength Degradation ◽  
Future Research ◽  
Frp Composites ◽  
Current Design ◽  
Frp Reinforcement ◽  
Superior Corrosion Resistance

Steel reinforcement in concrete has the tendency to corrode and this process can lead to structural damage. FRP reinforcement represents a viable alternative for structures exposed to aggressive environments and has many possible applications where superior corrosion resistance properties are required. The use of FRP rebars as internal reinforcements for concrete, however, is limited to specific structural elements and does not yet extend to the whole structure. The reasons for this relate to the limited availability of curved or shaped reinforcing elements on the market and their reduced structural performance. Various studies, in fact, have shown that the mechanical performance of bent portions of composite bars is reduced significantly under a multiaxial combination of stresses and that the tensile strength can be as low as 25% of the maximum tensile strength that can be developed in the straight part. In a significant number of cases, the current design recommendations for concrete structures reinforced with FRP, however, were found to overestimate the bend capacity of FRP rebar. This paper presents the state-of-the art review of the research works on the strength degradation in curved FRP composites and highlighted the performance of exiting predictive models for the bend capacity of FRP reinforcement. Recent practical predictive model based on the Tsai-Hill failure criteria by considering the material at marcromechanical level is also discussed and highlighted. The review also identifies the challenges and highlights the future directions of research to explore the use of shaped FRP composites in civil engineering applications and the trends for future research in this area.

scholarly journals Strength Degradation in Curved Fiber-reinforced Polymer (FRP) Bars Used as Concrete Reinforcement

Polymers ◽  
2020 ◽  
Vol 12 (8) ◽  
pp. 1653
Author(s):  
Thanongsak Imjai ◽  
Reyes Garcia ◽  
Maurizio Guadagnini ◽  
Kypros Pilakoutas
Keyword(s):  
Tensile Strength ◽  
Structural Damage ◽  
Mechanical Performance ◽  
Failure Criteria ◽  
Strength Degradation ◽  
Fiber Reinforced Polymer ◽  
Fiber Reinforced ◽  
Frp Composites ◽  
Reinforced Polymer ◽  
Frp Bars

Steel reinforcements in concrete tend to corrode and this process can lead to structural damage. Fiber-reinforced polymer (FRP) reinforcements represent a viable alternative for structures exposed to aggressive environments and have many possible applications where superior corrosion resistance properties are required. The use of FRP rebars as internal reinforcements for concrete, however, is limited to specific structural elements and does not yet extend to the whole structure. The reason for this relates to the limited availability of curved or shaped reinforcing FRP elements on the market, as well as their reduced structural performance. This article presents a state-of-the art review on the strength degradation of curved FRP composites, and also assesses the performance of existing predictive models for the bend capacity of FRP reinforcements. Previous research has shown that the mechanical performance of bent portions of FRP bars significantly reduces under a multiaxial combination of stresses. Indeed, the tensile strength of bent FRP bars can be as low as 25% of the maximum tensile strength developed in a straight counterpart. In a significant number of cases, the current design recommendations for concrete structures reinforced with FRP were found to overestimate the bend capacity of FRP bars. A more accurate and practical predictive model based on the Tsai–Hill failure criteria is also discussed. This review article also identifies potential challenges and future directions of research for exploring the use of curved/shaped FRP composites in civil engineering applications.

scholarly journals Experimental studies and theoretical models for concrete columns confined with FRP composites: a review

2019 ◽  
Vol 16 (4) ◽  
pp. 509-525
Author(s):  
Abdurra’uf M. Gora ◽  
Jayaprakash Jaganathan ◽  
M.P. Anwar ◽  
H.Y. Leung
Keyword(s):  
Concrete Columns ◽  
Theoretical Models ◽  
Experimental Investigations ◽  
Future Research ◽  
Content Type ◽  
Compressive Behaviour ◽  
Frp Composites ◽  
Frp Reinforcement ◽  
Frp Confinement ◽  
The Impact

Purpose Advanced fibre-reinforced polymer (FRP) composites have been increasingly used over the past two decades for strengthening, upgrading and restoring degraded civil engineering infrastructure. Substantial experimental investigations have been conducted in recent years to understand the compressive behaviour of FRP-confined concrete columns. A considerable number of confinement models to predict the compressive behaviour of FRP-strengthened concrete columns have been developed from the results of these experimental investigations. The purpose of this paper is to present a comprehensive review of experimental investigations and theoretical models of circular and non-circular concrete columns confined with FRP reinforcement. Design/methodology/approach The paper reviews previous experimental test results on circular and non-circular concrete columns confined with FRP reinforcement under concentric and eccentric loading conditions and highlights the behaviour and mechanics of FRP confinement in these columns. The paper also reviews existing confinement models for concrete columns confined with FRP composites in both circular and non-circular sections. Findings This paper demonstrates that the performance and effectiveness of FRP confinement in concrete columns have been extensively investigated and proven effective in enhancing the structural performance and ductility of strengthened columns. The strength and ductility enhancement depend on the number of FRP layers, concrete compressive strength, corner radius for non-circular columns and intensity of load eccentricity for eccentrically loaded columns. The impact of existing theoretical models and directions for future research are also presented. Originality/value Potential researchers will gain insight into existing experimental and theoretical studies and future research directions.

scholarly journals Determination of Critical Hydrogen Concentration and Its Effect on Mechanical Performance of 2200 MPa and 600 HBW Martensitic Ultra-High-Strength Steel

Metals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 984
Author(s):  
Eric Fangnon ◽  
Yuriy Yagodzinskyy ◽  
Evgenii Malictki ◽  
Saara Mehtonen ◽  
Esa Virolainen ◽  
...  
Keyword(s):  
Tensile Strength ◽  
Hydrogen Concentration ◽  
Mechanical Performance ◽  
Thermal Desorption Spectroscopy ◽  
Local Stress ◽  
High Strength ◽  
Constant Load ◽  
Strength Degradation ◽  
Load Test ◽  
Extension Rate

The influence of hydrogen on the mechanical performance of a hot-rolled martensitic steel was studied by means of constant extension rate test (CERT) and constant load test (CLT) followed with thermal desorption spectroscopy measurements. The steel shows a reduction in tensile strength up to 25% of ultimate tensile strength (UTS) at critical hydrogen concentrations determined to be about 1.1 wt.ppm and 50% of UTS at hydrogen concentrations of 2 wt.ppm. No further strength degradation was observed up to hydrogen concentrations of 4.8 wt.ppm. It was observed that the interplay between local hydrogen concentrations and local stress states, accompanied with the presence of total average hydrogen reducing the general plasticity of the specimen are responsible for the observed strength degradation of the steel at the critical concentrations of hydrogen. Under CLT, the steel does not show sensitivity to hydrogen at applied loads below 50% of UTS under continuous electrochemical hydrogen charging up to 85 h. Hydrogen enhanced creep rates during constant load increased linearly with increasing hydrogen concentration in the steel.

Enhanced Method of Predicting Tensile Strength Degradation of Steel Bridge Members Due to Corrosion

2012 ◽  
Vol 2 (1) ◽  
pp. 30-41
Author(s):  
J. M.R.S. Appuhamy ◽  
M. Ohga ◽  
T. Kaita ◽  
P. Chun ◽  
P. B.R. Dissanayake
Keyword(s):  
Tensile Strength ◽  
Strength Degradation ◽  
Steel Bridge

Effect of Polyethylene Glycol in Nanocellulose/PLA Composites

2019 ◽  
Vol 821 ◽  
pp. 89-95
Author(s):  
Wanasorn Somphol ◽  
Thipjak Na Lampang ◽  
Paweena Prapainainar ◽  
Pongdhorn Sae-Oui ◽  
Surapich Loykulnant ◽  
...  
Keyword(s):  
Tensile Strength ◽  
Lactic Acid ◽  
Polyethylene Glycol ◽  
Aspect Ratio ◽  
Mechanical Performance ◽  
Tensile Modulus ◽  
Poly Lactic Acid ◽  
Solvent Casting ◽  
Casting Method ◽  
Mediated Oxidation

Poly (lactic acid) or PLA was reinforced by nanocellulose and polyethylene glycol (PEG), which were introduced into PLA matrix from 0 to 3 wt.% to enhance compatibility and strength of the PLA. The nanocellulose was prepared by TEMPO-mediated oxidation from microcrystalline cellulose (MCC) powder and characterized by TEM, AFM, and XRD to reveal rod-like shaped nanocellulose with nanosized dimensions, high aspect ratio and high crystallinity. Films of nanocellulose/PEG/PLA nanocomposites were prepared by solvent casting method to evaluate the mechanical performance. It was found that the addition of PEG in nanocellulose-containing PLA films resulted in an increase in tensile modulus with only 1 wt% of PEG, where higher PEG concentrations negatively impacted the tensile strength. Furthermore, the tensile strength and modulus of nanocellulose/PEG/PLA nanocomposites were higher than the PLA/PEG composites due to the existence of nanocellulose chains. Visual traces of crazing were detailed to describe the deformation mechanism.

Microstructure and mechanical property improvement of dissimilar metal joints for TC4 Ti alloy to Nitinol NiTi alloy by laser welding

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Yan Zhang ◽  
DeShui Yu ◽  
JianPing Zhou ◽  
DaQian Sun ◽  
HongMei Li
Keyword(s):  
Tensile Strength ◽  
Laser Welding ◽  
Mechanical Performance ◽  
Niti Alloy ◽  
Welding Process ◽  
Ti Alloy ◽  
The One ◽  
Fusion Weld ◽  
Welding Processes ◽  
Cu Interlayer

Abstract To avoid the formation of Ti-Ni intermetallics in a joint, three laser welding processes for Ti alloy–NiTi alloy joints were introduced. Sample A was formed while a laser acted at the Ti alloy–NiTi alloy interface, and the joint fractured along the weld centre line immediately after welding without filler metal. Sample B was formed while the laser acted on a Cu interlayer. The average tensile strength of sample B was 216 MPa. Sample C was formed while the laser acted 1.2 mm on the Ti alloy side. The one-pass welding process involved the creation of a joint with one fusion weld and one diffusion weld separated by the remaining unmelted Ti alloy. The mechanical performance of sample C was determined by the diffusion weld formed at the Ti alloy–NiTi alloy interface with a tensile strength of 256 MPa.

scholarly journals Enhanced Tensile Strength of Monolithic Epoxy with Highly Dispersed TiO2-Graphene Nanocomposites

2021 ◽  
Vol 5 (7) ◽  
pp. 191
Author(s):  
Yanshuai Wang ◽  
Siyao Guo ◽  
Biqin Dong ◽  
Feng Xing
Keyword(s):  
Tensile Strength ◽  
Epoxy Resin ◽  
Mechanical Performance ◽  
Chemical Properties ◽  
High Mechanical Property ◽  
Graphene Nanocomposites ◽  
Highly Dispersed ◽  
Dispersion State ◽  
Physical And Chemical

The functionalization of graphene has been reported widely, showing special physical and chemical properties. However, due to the lack of surface functional groups, the poor dispersibility of graphene in solvents strongly limits its engineering applications. This paper develops a novel green “in-situ titania intercalation” method to prepare a highly dispersed graphene, which is enabled by the generation of the titania precursor between the layer of graphene at room temperature to yield titania-graphene nanocomposites (TiO2-RGO). The precursor of titania will produce amounts of nano titania between the graphene interlayers, which can effectively resist the interfacial van der Waals force of the interlamination in graphene for improved dispersion state. Such highly dispersed TiO2-RGO nanocomposites were used to modify epoxy resin. Surprisingly, significant enhancement of the mechanical performance of epoxy resin was observed when incorporating the titania-graphene nanocomposites, especially the improvements in tensile strength and elongation at break, with 75.54% and 176.61% increases at optimal usage compared to the pure epoxy, respectively. The approach presented herein is easy and economical for industry production, which can be potentially applied to the research of high mechanical property graphene/epoxy composite system.

scholarly journals A Comprehensive Investigation on 3D Printing of Polyamide 11 and Thermoplastic Polyurethane via Multi Jet Fusion

Polymers ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 2139
Author(s):  
Wei Shian Tey ◽  
Chao Cai ◽  
Kun Zhou
Keyword(s):  
Tensile Strength ◽  
Flexural Strength ◽  
Wear Rate ◽  
Mechanical Performance ◽  
Thermoplastic Polyurethane ◽  
Print Quality ◽  
Polyamide 11 ◽  
Powder Bed

Multi Jet Fusion (MJF) is a recently developed polymeric powder bed fusion (PBF) additive manufacturing technique that has received considerable attention in the industrial and scientific community due to its ability to fabricate functional and complex polymeric parts efficiently. In this work, a systematic characterization of the physicochemical properties of MJF-certified polyamide 11 (PA11) and thermoplastic polyurethane (TPU) powder was conducted. The mechanical performance and print quality of the specimens printed using both powders were then evaluated. Both PA11 and TPU powders showed irregular morphology with sharp features and had broad particle size distribution, but such features did not impair their printability significantly. According to the DSC scans, the PA11 specimen exhibited two endothermic peaks, while the TPU specimen exhibited a broad endothermic peak (116–150 °C). The PA11 specimens possessed the highest tensile strength in the Z orientation, as opposed to the TPU specimens which possessed the lowest tensile strength along the same orientation. The flexural properties of the PA11 and TPU specimens displayed a similar anisotropy where the flexural strength was highest in the Z orientation and lowest in the X orientation. The porosity values of both the PA11 and the TPU specimens were observed to be the lowest in the Z orientation and highest in the X orientation, which was the opposite of the trend observed for the flexural strength of the specimens. The PA11 specimen possessed a low coefficient of friction (COF) of 0.13 and wear rate of 8.68 × 10−5 mm3/Nm as compared to the TPU specimen, which had a COF of 0.55 and wear rate of 0.012 mm3/Nm. The PA11 specimens generally had lower roughness values on their surfaces (Ra < 25 μm), while the TPU specimens had much rougher surfaces (Ra > 40 μm). This investigation aims to uncover and explain phenomena that are unique to the MJF process of PA11 and TPU while also serving as a benchmark against similar polymeric parts printed using other PBF processes.

Biomechanical comparison of the Lim/Tsai tendon repair with a modified method using a single looped suture

2017 ◽  
Vol 42 (9) ◽  
pp. 915-919 ◽  
Author(s):  
Min Kai Chang ◽  
Yoke Rung Wong ◽  
Shian Chao Tay
Keyword(s):  
Tensile Strength ◽  
Ultimate Tensile Strength ◽  
Mechanical Performance ◽  
Tendon Repair ◽  
Original Method ◽  
Flexor Digitorum Profundus ◽  
Loading Test ◽  
Modified Method ◽  
Cycle Loading ◽  
The Difference

The Lim/Tsai tendon repair technique has been modified clinically to achieve a 6-strand repair using a single looped suture with one extratendinous knot. We compared biomechanical performance of the original and modified methods using 20 porcine flexor digitorum profundus tendons. The ultimate tensile strength, load to 2 mm gap force, mode of failure, and time taken to repair each tendon were recorded during a single cycle loading test in 10 tendons with each repair method. We found that despite having the same number of core strands, the single looped suture modified Lim/Tsai technique possessed significantly greater ultimate tensile strength and load to 2 mm gap force. Also, less repair time was required. We conclude that the modified 6-strand repair using a single looped suture has better mechanical performance than the original method. The difference likely was due to the changes in locations of the knots and subsequent load distribution during tendon loading.

scholarly journals The Influence of Manufacturing Parameters on the Mechanical Behaviour of PLA and ABS Pieces Manufactured by FDM: A Comparative Analysis

Materials ◽  
2018 ◽  
Vol 11 (8) ◽  
pp. 1333 ◽  
Author(s):  
Adrián Rodríguez-Panes ◽  
Juan Claver ◽  
Ana Camacho
Keyword(s):  
Tensile Strength ◽  
Mechanical Behaviour ◽  
Mechanical Performance ◽  
Acrylonitrile Butadiene Styrene ◽  
Polymer Materials ◽  
Fused Deposition Modelling ◽  
Fused Deposition ◽  
Layer Orientation ◽  
Lower Variability

This paper presents a comparative study of the tensile mechanical behaviour of pieces produced using the Fused Deposition Modelling (FDM) additive manufacturing technique with respect to the two types of thermoplastic material most widely used in this technique: polylactide (PLA) and acrylonitrile butadiene styrene (ABS). The aim of this study is to compare the effect of layer height, infill density, and layer orientation on the mechanical performance of PLA and ABS test specimens. The variables under study here are tensile yield stress, tensile strength, nominal strain at break, and modulus of elasticity. The results obtained with ABS show a lower variability than those obtained with PLA. In general, the infill percentage is the manufacturing parameter of greatest influence on the results, although the effect is more noticeable in PLA than in ABS. The test specimens manufactured using PLA perform more rigidly and they are found to have greater tensile strength than ABS. The bond between layers in PLA turns out to be extremely strong and is, therefore, highly suitable for use in additive technologies. The methodology proposed is a reference of interest in studies involving the determination of mechanical properties of polymer materials manufactured using these technologies.

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