Print ISSN: 1681-6900

Online ISSN: 2412-0758

Keywords : ductility

Study the Ductility of Aluminum Alloy Processed by Asymmetric Rolling Process

Adil. Sh. Jaber

Engineering and Technology Journal, 2020, Volume 38, Issue 10A, Pages 1461-1469
DOI: 10.30684/etj.v38i10A.899

Asymmetric rolling refers to the conditions wherein velocities or diameters of two work rolls are different. Compared to symmetrical rolling, asymmetric rolling is more effective on microstructure modification and texture evolution. Intense shear deformation can be introduced into asymmetric rolling to enhance the ductility and formability of aluminum alloy and this is the aim of current research. The process of the asymmetrical rolling was done on specimens with different reductions (10%,15%, and 20% reductions). Then the tensile test was conducted at room temperature at the strain rate range between 0.33×10-3s-1 - 3.33×10-3s-1 to study the ductility property of the asymmetric rolling-deformed samples and also compared with as-received samples. The results show that the as-received specimen gave the highest elongation of 42.7%, while the lowest elongation of 22.4% was obtained by the (20%) thickness reduction specimen. Also, the as-received sample at an initial strain rate of 3.33×10-3s-1 gives the highest tensile strength value equal to 550MPa.

Flexural Performance of Reinforced Concrete Built-up Beams with SIFCON

Ghazwan K. Mohammed; Kaiss F. Sarsam; Ikbal N. Gorgis

Engineering and Technology Journal, 2020, Volume 38, Issue 5, Pages 669-680
DOI: 10.30684/etj.v38i5A.501

The study deals with the effect of using Slurry infiltrated fiber concrete (SIFCON) with the reinforced concrete beams to explore its enhancement to the flexural capacity. The experimental work consists of the casting of six beams, two beams were fully cast by conventional concrete (CC) and SIFCON, as references. While the remaining was made by contributing a layer of SIFCON diverse in-depth and position, towards complete the overall depths of the built-up beam with conventional concrete CC. Also, an investigation was done through the control specimens testing about the mechanical properties of SIFCON. The results showed a stiffer behavior with a significant increase in load-carrying capacity when SIFCON used in tension zones. Otherwise high ductility and energy dissipation appeared when SIFCON placed in compression zones with a slight increment in ultimate load. The high volumetric ratio of steel fibers enabled SIFCON to magnificent tensile properties.

Experimental study of Circular Short Columns made from Reactive Powder Concrete

Asmaa Ali Ahmad; Faidhi Abdul-Rahman Alkhazraji; Sarah Mohammed Omar

Engineering and Technology Journal, 2016, Volume 34, Issue 9, Pages 1860-1872

This research studies the behavior of reactive powder concrete (RPC) circular short columns with and without steel fibers of different types, as well as change of the reinforcement kinds of lateral (hoops and spiral) and the spacing between them.
The experimental work consist study of fifteen short column specimens having an overall height of 1 m with circular cross-section of 150 mm diameter are loaded at ends with concentric loads. Six of the specimens are cast with the inclusion of steel fibers with aspect ratio of 75(group 1), and six of other specimens are cast with the inclusion of steel fibers with aspect ratio of 100 (group 2),and the other three specimens is without steel fibers, with hybrid steel fibers and high strength concrete. The concrete mix of fiber-reinforced samples contains 1% by volume of steel fibers of variable reinforcement longitudinal and lateral (hoops and spiral reinforcement).
Experimental data for strength, failure mode, lateral, and the ductility were obtained for each test.
The work concluded that the using of steel fibers in RPC was an effective way to prevent spalling of the concrete cover and increase the ductility and the using of high ratio of longitudinal reinforcement delays the pickling of the columns and increase strength.
The ultimate load capacity of RPC columns of spiral lateral reinforcement is greater than the load of RPC columns of tied lateral reinforcement by about 1.25 to 1.35 times for the two groups.

Flexural Strength and Ductility of CFRP Strengthened Reinforced Concrete Beams

Bayan S. Al-Numan; Jamal A. Farhan; Othman K. Ali

Engineering and Technology Journal, 2016, Volume 34, Issue 7, Pages 1294-1307

A total of fourteen beams, 100×150 mm in cross-section were tested in the laboratory over an effective span of 2000 mm. Two of them were used as reference beams. Twelve fiber reinforced concrete beams were provided with externally bonded CFRP laminates at the soffit of the beam. The variables considered included number of CFRP layers, yield strength of steel reinforcement (fy) and steel reinforcement ratio (). All the beams were tested until failure. The test results showed that the ultimate load carrying capacity increased by 56% as average by increasing of the ratio of steel reinforcement from (0.0127 to 0.0324). The deflection ductility index DDI values averaged (1.80) and (1.75) for one-layer strengthened beams and two-layer ones, respectively. The corresponding energy ductility index EDI values averaged (1.75) and (1.73), respectively. The DDI and EDI for the control beams were 4.61 and 6.24, respectively. With the exception of the control beams, all of the beams exhibited poor ductility. Failures in all strengthened beams were accompanied by the release of large amounts of energy (known as elastic energy) relative to inelastic energy. Therefore, a reasonable factor of safety should be used in the design of FRP strengthened reinforced concrete members.

Behavior of Aluminum Columns Enhanced with CFRP and Filled by Lightweight Concrete

ad Fahad Resan

Engineering and Technology Journal, 2014, Volume 32, Issue 11, Pages 2658-2672

An experimental study of composite columns of hollow circular aluminum tubes enhanced with a fibers reinforced polymer (FRP) sheet and filled by lightweight concrete are presented in this paper. The study's scope is introducing and developing lightweight columns to be advantageous in lightweight and size limited structures. The test results discussed the influence of internal and external confinement effectiveness introduced by lightweight concrete and carbon fiber reinforced polymer (CFRP) retrofitting sheet, respectively. The column specimens were subjected to uniform axial compression load. Structural aluminum alloy circular hollow section has been used in this investigation. Carbon fiber reinforced polymer (CFRP) is used to piling aluminum tubes. Light weight expansion clay aggregate (LECA) is used to fabricate light weight concrete filling aluminum tubes. The strengths, shortening displacement, axial strains, lateral strains, and failure modes of columns were presented. The test results indicated that confinement and composite action between the constituent materials resulted in enhanced compressive strength, ductility and energy dissipation capacity of the proposed composite column. Finally, a simplified design equation is proposed to predict the compressive load capacity of this type of composite column.

Effect of Concrete Compressive Strength and Compression Reinforcement in Compression Zone on the Ductility of Reinforced Concrete Beams

Sawsan Akram Hassan; Awadh Ewayed Ajeel

Engineering and Technology Journal, 2014, Volume 32, Issue 5, Pages 1106-1116

Ductility is a mechanical property used to describe the extent to which materials can be deformed plastically without fracture giving warning of impending failure. In this paper the effect of increasing the strength in the compression zone of reinforced concrete beams on ductility was investigated. Seven reinforced concrete beams were tested for this purpose. The tested beams were divided into two groups depending on the manner at which the strength of the compression zone was increased. In the first group, the increase was done by increasing the amount of compression reinforcement. Four ratios of compression reinforcement were adopted. In the second group, the increase in the strength of the compression zone was done by increasing the concrete compressive strength in the upper third of the cross section which was subjected to compression stresses. Four compressive strengths were adopted .One beam was used as reference for the two groups. It was found that, the compression zone strengthening, by the two manners, increases both strength and ductility of the beams; but the increases due to increase the ratio of compressive reinforcement is higher and more safety than that attained due to increasing concrete compressive strength.