scholarly journals Experimental Investigation of the Effects of Concrete Alkalinity on Tensile Properties of Preheated Structural GFRP Rebar

2017 ◽  
Vol 2017 ◽  
pp. 1-13 ◽  
Author(s):  
Hwasung Roh ◽  
Cheolwoo Park ◽  
Do Young Moon
Keyword(s):  
Tensile Strength ◽  
Elastic Modulus ◽  
High Temperature ◽  
Tensile Failure ◽  
Combined Effects ◽  
Test Results ◽  
Maximum Difference ◽  
Reinforcing Bars ◽  
Tensile Performance ◽  
Gfrp Bar

The combined effects of preexposure to high temperature and alkalinity on the tensile performance of structural GFRP reinforcing bars are experimentally investigated. A total of 105 GFRP bar specimens are preexposed to high temperature between 120°C and 200°C and then immersed into pH of 12.6 alkaline solution for 100, 300, and 660 days. From the test results, the elastic modulus obtained at 300 immersion days is almost the same as those of 660 immersion days. For all alkali immersion days considered in the test, the preheated specimens provide slightly lower elastic modulus than the unpreheated specimens, showing only 8% maximum difference. The tensile strength decreases for all testing cases as the increase of the alkaline immersing time, regardless of the prehearing levels. The tensile strength of the preheated specimens is about 90% of the unpreheated specimen for 300 alkali immersion days. However, after 300 alkali immersion days the tensile strengths are almost identical to each other. Such results indicate that the tensile strength and elastic modulus of the structural GFRP reinforcing bars are closely related to alkali immersion days, not much related to the preheating levels. The specimens show a typical tensile failure around the preheated location.

Experimental Study of High Temperature Performance of Steel Suspension Bridge Wires

2019 ◽  
Author(s):  
Jumari A. Robinson ◽  
Adrian Brügger ◽  
Raimondo Betti
Keyword(s):  
Elastic Modulus ◽  
High Temperature ◽  
High Strength Steel ◽  
Cold Working ◽  
High Strength ◽  
Suspension Bridge ◽  
Theoretical Models ◽  
Test Results ◽  
Single Wire ◽  
Steel Wires

<p>The performance of suspension bridges exposed to fire hazards is severely under-studied – so much so that no experimental data exists to quantify the safety of a suspension bridge during or after a major fire event. Bridge performance and safety rely on the integrity of the main cable and its constituent high-strength steel wires. Due to the current lack of experimental high temperature data for wires, the theoretical models use properties and coefficients from data for other types of structural steel. No other structural steel undergoes the amount of cold-working that bridge wire does, and plastic strains from cold-working can be relieved at high temperature, drastically weakening the steel. As such, this work determines the elastic modulus, ultimate strength, and general thermo-mechanical profile of the high-strength steel wires in a range of elevated temperature environments. Specifically, these tests are conducted on a bundle of 61-wires (transient), and at the single wire level (steady-state) at a temperature range of approximately 20-700°C. The test results show an alarmingly high reduction in the elastic modulus and ultimate strength with increased temperature. The degradation shown by experiments is higher than predicted by current theoretical models, indicating that use of high-temperature properties of other types of steel is not sufficient. The test results also show scaling agreement between the single wire and the 61-wire bundle, implying that a full material work up at the single- wire level will accurately inform the failure characterization of the full cable.</p>

A Fundamental Study on Anchor Performance of CFRP Tendons with Compressed Anchor Sleeve

2014 ◽  
Vol 1061-1062 ◽  
pp. 151-154
Author(s):  
Woo Tai Jung ◽  
Moon Seoung Keum ◽  
Sung Yong Choi ◽  
Jae Yoon Kang ◽  
Jong Sup Park
Keyword(s):  
Tensile Strength ◽  
Direct Application ◽  
Lateral Stiffness ◽  
Test Results ◽  
Fundamental Study ◽  
Bond Type ◽  
Bond Performance ◽  
Tensile Performance ◽  
Steel Sleeve

The anchoring of CFRP tendon can be performed by wedging, bonding or compressing. The wedge type anchor, used for PS steel tendon, is inappropriate for direct application to the CFRP tendon due to its low lateral stiffness. Since the bond performance of the CFRP tendon depends on the anchor performance, the bond type anchor presents the problem of requiring long steel sleeve in case of low bond performance or high tensile performance. Compared to the bond type anchor, the compressing type anchor offers better applicability but necessitates the development of a sleeve fitted to the dimensions of each CFRP tendon. This study intends to examine the anchoring characteristics of the compressed sleeve for the temporary anchorage of a CFRP tendon with diameter of 10 mm. To that goal, the properties of the 10 mm-diameter CFRP tendon were assessed using the bond type anchor and the corresponding anchor performance is compared to that of the compressed anchor. The test results revealed that the use of spacers in the compressed anchor provided lower anchor performance due to the characteristics of the spacers. For the specimen without spacer, the micro-deformations formed inside the sleeve were seen to compress the CFRP tendon by gearing directly the tendon and to provide anchor performance reaching about 72% of the tensile strength of the CFRP tendon. Further study shall develop a sleeve with increased compress force on the CFRP tendon so as to improve the anchor performance of the compressed sleeve. Moreover, solution shall also be provided to introduce a uniform compress force.

scholarly journals Mechanical properties of blueberry stems

2018 ◽  
Vol 64 (No. 4) ◽  
pp. 202-208
Author(s):  
Margus Arak ◽  
Kaarel Soots ◽  
Marge Starast ◽  
Jüri Olt
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Elastic Modulus ◽  
Structural Parameters ◽  
Tensile Tests ◽  
Measuring Instrument ◽  
Test Results ◽  
Average Value ◽  
Agricultural Machines

In order to model and optimise the structural parameters of the working parts of agricultural machines, including harvesting machines, the mechanical properties of the culture harvested must be known. The purpose of this article is to determine the mechanical properties of the blueberry plant’s stem; more precisely the tensile strength and consequent elastic modulus E. In order to achieve this goal, the measuring instrument Instron 5969L2610 was used and accompanying software BlueHill 3 was used for analysing the test results. The tested blueberry plant’s stems were collected from the blueberry plantation of the Farm Marjasoo. The diameters of the stems were measured, test units were prepared, tensile tests were performed, tensile strength was determined and the elastic modulus was obtained. Average value of the elastic modulus of the blueberry (Northblue) plant’s stem remained in the range of 1268.27–1297.73 MPa.

Effect of Blending Modification on Tensile Performance of CPE/PVC

2011 ◽  
Vol 284-286 ◽  
pp. 1732-1735
Author(s):  
Xiao Ling Xie ◽  
Wen Hai Li ◽  
Ying Hui Wei
Keyword(s):  
Tensile Strength ◽  
Polyvinyl Chloride ◽  
Hot Pressing ◽  
Mechanical Performance ◽  
Dioctyl Phthalate ◽  
Test Results ◽  
Pressing Temperature ◽  
Chlorinated Polyethylene ◽  
Breaking Elongation ◽  
Tensile Performance

The samples were modified by using chlorinated polyethylene (CPE) to increase the toughness and using dioctyl phthalate (DOP) to increase the plasticity. The tensile strength and breaking elongation of the samples were studied by changing the chlorinated polyethylene (CPE) and dioctyl phthalate (DOP) contents and the hot-pressing temperature. It was shown by the test results that, with the increase of chlorinated polyethylene (CPE) and dioctyl phthalate (DOP) contents, the tensile strength of the samples was decreased while the breaking elongation was increased. By increasing the hot-pressing temperature, the blending effect between polyvinyl chloride (PVC) and chlorinated polyethylene (CPE) as well as the mechanical performance of the samples were increased, however, over-high hot-pressing temperature would result in plasticizer precipitation.

scholarly journals Combined Effects of Sustained Loads and Wet-Dry Cycles on Durability of Glass Fiber Reinforced Polymer Composites

2017 ◽  
Vol 2017 ◽  
pp. 1-14
Author(s):  
Mengting Li ◽  
Jun Wang ◽  
Weiqing Liu ◽  
Ruifeng Liang ◽  
Hota GangaRao ◽  
...  
Keyword(s):  
Tensile Strength ◽  
Elastic Modulus ◽  
Fiber Reinforced Polymer ◽  
Distilled Water ◽  
Combined Effects ◽  
Gfrp Composites ◽  
Glass Fiber Reinforced Polymer ◽  
Reinforced Polymer ◽  
Glass Fiber Reinforced ◽  
Sustained Loads

This paper deals with durability of glass fiber reinforced polymer (GFRP) composites under the combined effects of sustained tensile loads and wet-dry (WD) cycles. Two different solutions (distilled water and saltwater) were used to imitate the freshwater and marine environments, respectively. Tensile properties of the unconditioned and conditioned specimens were measured to study the durability of GFRP composites under these 2 effects. The response indicated that both tensile strength and elastic modulus increased initially upon WD cycles, which was attributed to both the postcuring of resin and the sustained tensile stress allowing for fastec cure. Further exposure to WD cycles in distilled water or saltwater led to a steady decrease in tensile strength and modulus. WD cycles of saltwater and distilled water have similar effects on the degradation of the tensile properties for unstressed specimens. However, the elastic modulus and elongation at rupture of stressed specimens under WD cycles of saltwater decreased more than those specimens under WD cycles of distilled water. Moreover, increase of sustained loads led to a decrease in tensile strength. Based on Arrhenius method, a prediction model which accounted for the effects of postcure processes was developed. The predicted results of tensile strength and elastic modulus agree well with those obtained from the experiments.

scholarly journals Buildability and Mechanical Properties of 3D Printed Concrete

Materials ◽  
2020 ◽  
Vol 13 (21) ◽  
pp. 4919
Author(s):  
Changbin Joh ◽  
Jungwoo Lee ◽  
The Quang Bui ◽  
Jihun Park ◽  
In-Hwan Yang
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Construction Industry ◽  
Test Results ◽  
Interval Time ◽  
Tensile Performance ◽  
3D Printed ◽  
Buckling Failure ◽  
Wide Contact ◽  
Printing Processes

Recently, 3D concrete printing has progressed rapidly in the construction industry. However, this technique still contains several factors that influence the buildability and mechanical properties of the printed concrete. Therefore, this study investigated the effects of the nozzle speed, the interlayer interval time, the rotations per minute (RPMs) of the screw in the 3D printing device, and the presence of lateral supports on the buildability of 3D concrete printing. In addition, this paper presents the results of the mechanical properties, including the compressive, splitting tensile, and flexural tensile strengths of 3D printed concrete. The buildability of 3D printed structures was improved with an extended interlayer interval time of up to 300 s. The printing processes were interrupted because of tearing of concrete filaments, which was related to excessive RPMs of the mixing screw. The test results also showed that a lateral support with a wide contact surface could improve the resistance to buckling failure for 3D printed structures. The test results of the mechanical properties of the 3D printed concrete specimens indicated that the compressive, splitting tensile, and flexural tensile strengths significantly depended on the bonding behavior at the interlayers of the printed specimens. In addition, although metal laths were expected to improve the tensile strength of the printed specimens, they adversely affected the tensile performance due to weak bonding between the reinforcements and concrete filaments.

Research on Tensile Mechanical Properties of GFRP Rebar after High Temperature

2011 ◽  
Vol 181-182 ◽  
pp. 349-354 ◽  
Author(s):  
Ya Nan Fu ◽  
Jun Zhao ◽  
Ya Li Li
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Elastic Modulus ◽  
High Temperature ◽  
Test Section ◽  
Tensile Tests ◽  
Tensile Elastic Modulus ◽  
Temperature Test

By tensile tests on GFRP rebar after high temperature, the change regularity and influent factor are analyzed. The results show that: With the temperature increasing, vitrification, carbonization, decomposition at high temperature test section of the GFRP rebar are aggravating , and their mechanical properties are deteriorating. At the same time, the limited tensile strength and ultimate tensile elastic modulus decreased in different degree.

scholarly journals Effect of Starch Nanocrystals on the Properties of Low Density Polyethylene/Thermoplastic Starch Blends

2020 ◽  
Vol 10 (4) ◽  
pp. 5875-5881
Author(s):  
S. Chaoui ◽  
D. Smail ◽  
A. Hellati ◽  
D. Benachour
Keyword(s):  
Tensile Strength ◽  
Elastic Modulus ◽  
Thermoplastic Starch ◽  
Low Density Polyethylene ◽  
Low Density ◽  
Dicumyl Peroxide ◽  
Test Results ◽  
Starch Blends ◽  
Internal Mixer ◽  
Starch Nanocrystals

In this study, Low Density Polyethylene (LDPE) and Thermoplastic Starch (TPS) reinforced with different amounts of Starch Nanocrystals (SNCs) with and without Dicumyl Peroxide (DCP) were blended in an internal mixer. The XRD results showed that crystallinity decreases with increasing SNC content with and without DCP. Tensile test results showed that elongation at breaking, tensile strength, and elastic modulus are lower than that of neat LDPE, whereas, the elastic modulus for the LDPE/TPS/SNC5%/DCP is higher than that of LDPE. AFM showed a decrease in the roughness of the surface after the addition of SNC and the surface become less rough after DCP addition.

scholarly journals Comparison of Tensile and Fatigue Properties of Copper Thin Film Depending on Process Method

2020 ◽  
Vol 10 (1) ◽  
pp. 388
Author(s):  
Hyeon-Gyu Min ◽  
Dong-Joong Kang ◽  
Jun-Hyub Park
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Tensile Strength ◽  
Elastic Modulus ◽  
Rolling Process ◽  
Fatigue Tests ◽  
Test Results ◽  
Fabrication Method ◽  
Copper Thin Film ◽  
Electrodeposition Process

In this study, tensile and fatigue tests were performed and analyzed to evaluate an influence of fabrication method on mechanical characteristics of copper thin film which widely used in flexible printed circuit board (FPCB). In general, manufacturing methods are known to affect the mechanical properties of materials, especially for thin films. The copper thin film is manufactured by a rolling process or an electrodeposition process. Therefore, specimen for tensile and fatigue tests were fabricated using by etching process with the rolled and electrodeposited thin films. First, the tensile tests were performed to obtain the elastic modulus, 0.2% offset yield stress, and tensile strength of the rolled copper and the electrodeposited copper thin film. Second, the copper thin films in FPCB is most often subjected to mechanical or/and thermal cyclic loading. The fatigue tests were performed to compare the fatigue characteristics and to evaluate an influence of fabrication method. Tensile test results showed that the elastic modulus was similar for each process, but the 0.2% yield strength and ultimate tensile strength were greater in the rolling process. In addition, the fatigue test results show that the copper thin films by the rolling process are better than by the electrodeposition process in fatigue life in all region.

Test Research on Mechanical Property of GFRP Bolt under Freeze-Thaw Cycle Conditions

2012 ◽  
Vol 531-532 ◽  
pp. 689-694
Author(s):  
Xie Xing Tang ◽  
Xiao Yong Luo ◽  
Qi Sun ◽  
Ya Chuan Kuang
Keyword(s):  
Mechanical Property ◽  
Tensile Strength ◽  
Elastic Modulus ◽  
Ultimate Tensile Strength ◽  
Test Results ◽  
Freeze Thaw ◽  
Thaw Cycle ◽  
Freeze Thaw Cycle ◽  
The Times

In this paper, GFRP bolts in diameter of 25mm are tested through freeze-thaw cycle by 50, 100 and 150 times to study their change law of appearance, weight, strength and elastic modulus. As reflected from the test results, after the freeze-thaw cycle, the appearance and weight of GFRP bolts are basically not changed. As the freeze-thaw cycle increases from 50 times to 100 times, the strength of bolts decreases gradually. After 50, 100 and 150 times of freeze-thaw cycle, the ultimate tensile strength of bolt decreases by 2.82%, 4.35% and 8.84%, respectively. During the process that the times of freeze-thaw cycle increase from 50 to 100, the elastic modulus of GFRP bolts grows gradually. After 50, 100 and 150 times of freeze-thaw cycle, the elastic modulus increases by 1.42%, 2.68% and 3.92%, respectively. The freeze-thaw cycle leads to embrittlement of GFRP materials and weakness of ductility, while not obviously.

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