scholarly journals Rheological Relaxation of OSB Beams Reinforced with CFRP Composites

Materials ◽  
2021 ◽  
Vol 14 (24) ◽  
pp. 7527
Author(s):  
Tomasz Socha ◽  
Krzysztof Kula ◽  
Arkadiusz Denisiewicz ◽  
Grzegorz Lesiuk ◽  
Wojciech Błażejewski
Keyword(s):  
Bending Test ◽  
Relaxation Problem ◽  
Four Point Bending ◽  
Reinforced Polymer ◽  
Reinforced Beams ◽  
Viscoelastic Element ◽  
Relaxation Curves ◽  
The Mathematical Model ◽  
Wood Based Composite ◽  
Theoretical Results

An experimental and analytical approach to the relaxation problem of wood-based materials—OSB (Oriented Strand Boards—pressed wood-based composite panels) beams, including beams with CFRP (Carbon fiber reinforced polymer) tape composite reinforcement, is presented. It is a relevant engineering and scientific problem due to the fact that wood and wood-based materials, as well as composite reinforcements, are widely used in building constructions. Their rheological properties are very important and complicated to estimate. A 10 day long relaxation test of thick OSB beams without reinforcement and with CFRP tape was performed. A four-point bending test with five different bending levels was performed, during which the reduction of the loading force was measured. A five-parameter rheological model was used to describe the rheology of the beams. The equations of this model were calculated with the use of Laplace transform, whereas the values of the parameters were calculated based on the experimental relaxation curves. A high correlation between experimental and theoretical results was obtained. A beam reinforced with CFRP tape was treated as a system with a viscoelastic element (OSB) and an elastic element (CFRP), joined together without the possibility of slipping. The equations of the mathematical model were calculated based on the assumptions of the linear theory of viscoelasticity and the convolution integral. A good correlation between experimental and theoretical results was obtained. A significant redistribution of stresses was observed during the relaxation of the reinforced beam. The reinforced beams show a higher stiffness of approximately 63% and carry proportionally higher loads than unreinforced beams at the same deflection values.

Experimental Testing of Fiber Reinforced Polymer-Concrete Composite Beam

2010 ◽  
Vol 168-170 ◽  
pp. 549-552
Author(s):  
Yan Lei Wang ◽  
Qing Duo Hao ◽  
Jin Ping Ou
Keyword(s):  
Composite Beam ◽  
Experimental Testing ◽  
Coarse Sand ◽  
Fiber Reinforced Polymer ◽  
Bending Test ◽  
Polymer Concrete ◽  
Fiber Reinforced ◽  
Four Point Bending ◽  
Reinforced Polymer ◽  
Box Beam

A new form of fiber reinforced polymer (FRP)-concrete composite beam is proposed in this study. The proposed composite beam consists of a GFRP box beam combined with a thin layer of concrete in the compression zone. The interaction between the GFRP beam and the concrete was obtained by bonding coarse-sand on the top flange of the GFRP beam. One GFRP box beam and one GFRP-concrete composite beam were investigated in four-point bending test. Load-deflection response, mid-span longitudinal strain distributions and interface slip between GFRP beam and the concrete for the proposed composite beam were studied. Following conclusions are drawn from this study: (1) the stiffness and strength of the composite beam has been significantly increased, and the cost-to-stiffness ratio of the composite beam has been drastically reduced comparing with GFRP-only box beam; (2) a good composite action has been achieved between the GFRP beam and the concrete; (3) crushing of concrete in compression defines flexural collapse of the proposed composite beam..

scholarly journals Strengthening Reinforced Concrete Beams with CFRP and GFRP

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Mehmet Mustafa Önal
Keyword(s):  
Concrete Beams ◽  
Reinforced Concrete Beams ◽  
Fiber Reinforced Polymer ◽  
Strength Increase ◽  
Fiber Reinforced ◽  
Flexural Stress ◽  
Four Point Bending ◽  
Reinforced Polymer ◽  
Glass Fiber Reinforced ◽  
Reinforced Beams

Concrete beams were strengthened by wrapping the shear edges of the beams twice at 45° in opposite directions by either carbon fiber reinforced polymer (CFRP) or glass fiber reinforced polymer (GFRP). The study included 3 CFRP wrapped beams, 3 GFRP wrapped beams, and 3 control beams, all of which were 150×250×2200 mm and manufactured with C20 concrete and S420a structural steel at the Gazi University Technical Education Faculty labs, Turkey. Samples in molds were cured by watering in the open air for 21 days. Four-point bending tests were made on the beam test specimens and the data were collected. Data were evaluated in terms of load displacement, bearing strength, ductility, and energy consumption. In the CFRP and GFRP reinforced beams, compared to controls, 38% and 42%, respectively, strength increase was observed. In all beams, failure-flexural stress occurred in the center as expected. Most cracking was observed in the flexural region 4. A comparison of CFRP and GFRP materials reveals that GFRP enforced parts absorb more energy. Both materials yielded successful results. Thicker epoxy application in both CFRP and GFRP beams was considered to be effective in preventing break-ups.

scholarly journals Experimental and Theoretical Study of Sandwich Panels with Steel Facesheets and GFRP Core

2016 ◽  
Vol 2016 ◽  
pp. 1-12 ◽  
Author(s):  
Hai Fang ◽  
Huiyuan Shi ◽  
Yue Wang ◽  
Yujun Qi ◽  
Weiqing Liu
Keyword(s):  
Fem Simulation ◽  
Sandwich Panels ◽  
Transformation Method ◽  
Steel Plates ◽  
Bending Test ◽  
Composite Sandwich ◽  
Four Point Bending ◽  
Reinforced Polymer ◽  
Glass Fiber Reinforced ◽  
Ultimate Failure

This study presented a new form of composite sandwich panels, with steel plates as facesheets and bonded glass fiber-reinforced polymer (GFRP) pultruded hollow square tubes as core. In this novel panel, GFRP and steel were optimally combined to obtain high bending stiffness, strength, and good ductility. Four-point bending test was implemented to analyze the distribution of the stress, strain, mid-span deflection, and the ultimate failure mode. A section transformation method was used to evaluate the stress and the mid-span deflection of the sandwich panels. The theoretical values, experimental results, and FEM simulation values are compared and appeared to be in good agreement. The influence of thickness of steel facesheet on mid-span deflection and stress was simulated. The results showed that the mid-span deflection and stress decreased and the decent speed was getting smaller as the thickness of steel facesheet increases. A most effective thickness of steel facesheet was advised.

Experimental Study of Concrete Beams Reinforced with GFRP Rebars Exposed to High Temperatures

2019 ◽  
Vol 808 ◽  
pp. 177-182
Author(s):  
Petr Daněk ◽  
Iva Rozsypalová ◽  
Ondřej Karel
Keyword(s):  
Experimental Study ◽  
High Temperatures ◽  
Concrete Beams ◽  
Bending Test ◽  
Four Point Bending ◽  
Reinforced Polymer ◽  
Glass Fibre Reinforced Polymer ◽  
Fibre Reinforced Polymer ◽  
Glass Fibre Reinforced ◽  
Gfrp Rebars

The paper deals with the experimental study of the behaviour of large concrete beams reinforced with glass fibre reinforced polymer (GFRP) rebars exposed to high temperatures equivalent to fire load. The four-point bending test was carried out on the beams after cooling. This study provided values for the load bearing capacity of the beams.

scholarly journals Delamination mechanism of GFRP sheet bonded on the reinforced concrete beams

2019 ◽  
Vol 258 ◽  
pp. 03009 ◽  
Author(s):  
Rudy Djamaluddin ◽  
Hijriah ◽  
Rita Irmawati ◽  
Faharuddin ◽  
Rossy T. Wahyuningsih
Keyword(s):  
Concrete Beams ◽  
Concrete Surface ◽  
Reinforced Concrete Beams ◽  
Fiber Reinforced Polymer ◽  
Bending Test ◽  
Four Point Bending ◽  
Reinforced Polymer ◽  
Direct Tensile ◽  
Bonding Characteristics ◽  
Surface Glass

Fiber reinforced polymer (FRP) has been developed to be applied for a strengthening of the deteriorated structures. In the form of a sheet, the FRP may be applied for the strengthening of the structures by bonding it to the concrete surface. Glass composed FRP (GFRP) sheet is most commonly used due to its relatively lower cost compared to the other FRP materials. GFRP sheet is applied externally by bonding it on the concrete surface. The strengthened structures should be monitored periodically to ensure the health of the strengthened structures. Regarding the development of monitoring system of the strengthened structure, it is important to study the delamination phenomenon of the bonded GFRP. Therefore the delamination mechanism is important to be clarified. Many studies have been done to investigate the bonding characteristics of GFRP sheet under direct tensile loading. However, the studies on the bonding characteristics of GFRP sheet on the strengthened beams due to flexural loadings are still limited. A series of concrete beams strengthened with GFRP sheet on extreme tension surface were prepared. The beam specimens ware loaded under four-point bending test gradually up to the ultimate capacity. Results indicated that prior to final delamination, a local delamination occurred which was indicated by the suddenly decreasing of an applied load. The delamination of the GFRP sheet may be initiated by the flexural cracks occurred on the beams.

scholarly journals Development of Highly Sensitive Strain Sensor Using Area-Arrayed Graphene Nanoribbons

Nanomaterials ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1701
Author(s):  
Ken Suzuki ◽  
Ryohei Nakagawa ◽  
Qinqiang Zhang ◽  
Hideo Miura
Keyword(s):  
Graphene Nanoribbons ◽  
Strain Sensor ◽  
Strain Sensors ◽  
Sensitive Strain ◽  
Bending Test ◽  
Gauge Factor ◽  
Four Point Bending ◽  
Current Voltage ◽  
Highly Sensitive ◽  
Current Voltage Relationship

In this study, a basic design of area-arrayed graphene nanoribbon (GNR) strain sensors was proposed to realize the next generation of strain sensors. To fabricate the area-arrayed GNRs, a top-down approach was employed, in which GNRs were cut out from a large graphene sheet using an electron beam lithography technique. GNRs with widths of 400 nm, 300 nm, 200 nm, and 50 nm were fabricated, and their current-voltage characteristics were evaluated. The current values of GNRs with widths of 200 nm and above increased linearly with increasing applied voltage, indicating that these GNRs were metallic conductors and a good ohmic junction was formed between graphene and the electrode. There were two types of GNRs with a width of 50 nm, one with a linear current–voltage relationship and the other with a nonlinear one. We evaluated the strain sensitivity of the 50 nm GNR exhibiting metallic conduction by applying a four-point bending test, and found that the gauge factor of this GNR was about 50. Thus, GNRs with a width of about 50 nm can be used to realize a highly sensitive strain sensor.

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