CURVATURE DUCTILITY PREDICTION OF REINFORCED HIGH‐STRENGTH CONCRETE BEAM SECTIONS

2010 ◽  
Vol 16 (4) ◽  
pp. 462-470 ◽  
Author(s):  
Guray Arslan ◽  
Ercan Cihanli
Keyword(s):  
High Strength Concrete ◽  
Structural Parameters ◽  
Limit State ◽  
High Strength ◽  
Reinforced Concrete Beams ◽  
Ultimate Limit State ◽  
Factors Affecting ◽  
Strength Concrete ◽  
Curvature Ductility ◽  
Major Factors

The ductility of reinforced concrete beams is very important, since it is essential to avoid a brittle failure of the structure by ensuring adequate curvature at the ultimate limit state. One of the procedures used to quantify ductility is based on curvatures, namely, curvature ductility. It is necessary to know the curvature ductility of singly reinforced high‐strength concrete (HSC) sections for determining a maximum permissible tensile reinforcement ratio or a maximum depth of the concrete compression area in design codes. The requirements of several codes and methods of prediction of the curvature ductility are based on the experimental results of normal strength concrete (NSC). The rules derived for NSC sections may not be appropriate for HSC sections, and verifications and modifications may be required for the evaluation of curvature ductility of HSC sections. In this study, the major factors affecting the curvature ductility of a singly reinforced HSC beam section are investigated. Based on numerical analyses, a parametric study has been carried out to evaluate the effects of various structural parameters on the curvature ductility of reinforced HSC beam sections. Santrauka Gelžbetoniniu siju plastiškumas yra labai svarbi savybe, apsauganti konstrukcija nuo staigios irties. Tam užtikrinti reikalinga atitinkama kreive, esant tinkamumo ribiniam būviui. Plastiškumas ivertinamas naudojant kreivines diagramas – plastiškumo kreives. Norint nustatyti didžiausia tempiamos armatūros kieki arba didžiausia gniuždomosios zonos aukšti, remiantis normomis reikia žinoti armuoto stipriojo betono (HSC) plastiškumo kreive. Kai kurios normos ir metodai plas‐tiškumo kreive nustato pagal paprastojo betono (NSC) eksperimentinius duomenis. Taisykles, skirtos paprastojo betono skerspjūvio plastiškumo kreivei nustatyti, gali netikti stipriajam betonui, todel reikia atlikti papildomus tyrimus ir metodu pakeitimus. Šiame darbe tiriami pagrindiniai veiksniai, darantys itaka stipriojo betono plastiškumo kreivei. Atliekant skai‐tini modeliavima, buvo ivertinti ivairūs skerspjūvio konstrukciniai parametrai, darantys poveiki stipriojo betono plas‐tiškumo kreivei.

scholarly journals Transverse Deformations and Structural Phenomenon as Indicators of Steel Fibred High-Strength Concrete Nonlinear Behavior

2019 ◽  
Vol 2019 ◽  
pp. 1-9 ◽  
Author(s):  
Iakov Iskhakov ◽  
Yuri Ribakov
Keyword(s):  
High Strength Concrete ◽  
High Efficiency ◽  
Limit State ◽  
Nonlinear Behavior ◽  
High Strength ◽  
Steel Fibers ◽  
Ultimate Limit State ◽  
Strength Concrete ◽  
Brittle Behavior ◽  
Ductile Behavior

As known, high-strength compressed concrete elements have brittle behavior, and elastic-plastic deformations do not appear practically up to their ultimate limit state (ULS). This problem is solved in modern practice by adding fibers that allow development of nonlinear deformations in such elements. As a rule, are applied steel fibers that proved high efficiency and contribute ductile behavior of compressed high-strength concrete (HSC) elements as well as the desired effect at long-term loading (for other types of fibers, the second problem is still not enough investigated). However, accurate prediction of the ULS for abovementioned compression elements is still very important and current. With this aim, it is proposed to use transverse deformations in HSC to analyze compression elements' behavior at stages close to ultimate. It is shown that, until the appearance of nonlinear transverse deformations (cracks formation), these deformations are about 5-6 times lower than the longitudinal ones. When cracks appear, the tensile stress-strain relationship in the transverse direction becomes nonlinear. This fact enables to predict that the longitudinal deformations approach the ultimate value. Laboratory tests were carried out on 21 cylindrical HSC specimens with various steel fibers content (0, 20, 30, 40, and 60 kg/m3). As a result, dependences of transverse deformations on longitudinal ones were obtained. These dependences previously proposed by the authors’ concept of the structural phenomenon allow proper estimation of the compressed HSC state up to failure. Good agreement between experimental and theoretical results forms a basis for further development of modern steel fibered HSC theory and first of all nonlinear behavior of HSC.

scholarly journals Flexure Behaviour of Reinforced High Strength Concrete Elements Affected by Corrosion

2019 ◽  
Vol 289 ◽  
pp. 10009
Author(s):  
Camelia Negrutiu ◽  
Ioan Sosa ◽  
Bogdan Heghes
Keyword(s):  
High Strength Concrete ◽  
Limit State ◽  
High Strength ◽  
Concrete Cover ◽  
Ultimate Limit State ◽  
Accelerated Corrosion ◽  
Strength Concrete ◽  
Significant Strength ◽  
Bending Capacity ◽  
State Position

Corrosion of the reinforcement is a constant vulnerability for reinforced concrete structures exposed to aggressive environments. High strength concrete is known to prevent corrosion of the reinforcement, in a non-cracked state, when exposed to aggressive environments. The purpose of this study is to assess the opportunity of using high strength concrete in cracked elements exposed to corrosion and compare them with non-exposed elements. A series of simply supported reinforced high strength concrete beams with concrete cover of 25 and 50 mm were pre-cracked, up to a service life crack of 0.1 mm, further exposed to accelerated corrosion through a process of electrolysis and finally tested to failure. A series of non-exposed witness specimens were also tested to failure. All elements were designed with the same bending capacity. The flexure behaviour was assessed by plotting experimental and theoretical ultimate limit state position of the neutral axis at midspan and the results show no significant differences in the overall behaviour, despite the affected reinforcement, between the corroded and non-corroded elements. Moreover, the design bending moments were approximately 40% lower than the experimental ones, even for corroded beams, which can be a significant strength reserve of the beams, useful in aggressive environments.

Influence of Nano Particles in the Flexural Behavior of High-Strength Reinforced Concrete Beams

2021 ◽  
Vol 1160 ◽  
pp. 25-43
Author(s):  
Naglaa Glal-Eldin Fahmy ◽  
Rasha El-Mashery ◽  
Rabiee Ali Sadeek ◽  
L.M. Abd El-Hafaz
Keyword(s):  
Tensile Strength ◽  
Compressive Strength ◽  
High Strength Concrete ◽  
High Strength ◽  
Reinforced Concrete Beams ◽  
Nano Particles ◽  
Flexural Behavior ◽  
Single Type ◽  
Strength Concrete ◽  
Flexural Ductility

High strength concrete (HSC) characterized by high compressive strength but lower ductility compared to normal strength concrete. This low ductility limits the benefit of using HSC in building safe structures. Nanomaterials have gained increased attention because of their improvement of mechanical properties of concrete. In this paper we present an experimental study of the flexural behavior of reinforced beams composed of high-strength concrete and nanomaterials. Eight simply supported rectangular beams were fabricated with identical geometries and reinforcements, and then tested under two third-point loads. The study investigated the concrete compressive strength (50 and 75 N/mm2) as a function of the type of nanomaterial (nanosilica, nanotitanium and nanosilica/nanotitanium hybrid) and the nanomaterial concentration (0%, 0.5% and 1.0%). The experimental results showed that nano particles can be very effective in improving compressive and tensile strength of HSC, nanotitanium is more effective than nanosilica in compressive strength. Also, binary usage of hybrid mixture (nanosilica + nanotitanium) had a remarkable improvement appearing in compressive and tensile strength than using the same percentage of single type of nanomaterials used separately. The reduction in flexural ductility due to the use of higher strength concrete can be compensated by adding nanomaterials. The percentage of concentration, concrete grade and the type of nanomaterials, could predominantly affect the flexural behavior of HSRC beams.

scholarly journals LIGHTER HIGH STRENGTH CONCRETE BEAM

2019 ◽  
Vol 2 (2) ◽  
pp. 17-26
Author(s):  
Nuri Mohamed Elbasha
Keyword(s):  
High Strength Concrete ◽  
Construction Projects ◽  
High Strength ◽  
Reinforced Concrete Beams ◽  
Limited Information ◽  
Experimental Proof ◽  
Strength Concrete ◽  
Project Costs ◽  
Normal Strength ◽  
The Cost

High strength concrete (HSC) has been used extensively in civil construction projects worldwide because it reduces the cross section and the weight of long construction members. In recent years a marked increase in the use of High Strength Concrete (HSC) has been evident in Australian building construction despite the fact that the current Australian design standard provides no design rules for such a material. Very limited information on the properties of HSC and its design and construction processes are available in Australia, although in recent times many studies have been undertaken to produce material and, more importantly, to determine its characteristic. In the last 20 years there has been extensive research to economically utilize new components to improve the quality of HSC. HSC produces smaller but stronger structural elements with large spaces available. It has been studied that the cost of using HSC instead of Normal Strength Concerete (NSC) in different types of constructions. This proved that structures constructed with HSC are lighter and economical compared with those constructed with NSC. In the long term durability significantly affects project costs. In other words after several years a concrete structure needs rehabilitation or in critical cases must be demolished, therefore the price of a project consists of initial costs plus those covering any rehabilitation. A huge amount of money could be saved by utilizing the durability characteristics of high strength concrete. This study presents recent information and the benefits of high strength concrete. Also, provides in brief an experimental proof that installing a helix with a suitable pitch and diameter in the compression zone of beams significantly enhances their strength and ductility. Therefore, designers could confidently use high-strength concrete and helical confinement to design long and light reinforced concrete beams.

Repaired Reinforced Concrete Beams with Normal and High Strength Concrete

2013 ◽  
Vol 6 (2) ◽  
pp. 21-37
Author(s):  
Emad Yassin Khudhair
Keyword(s):  
Reinforced Concrete ◽  
High Strength Concrete ◽  
High Strength ◽  
Fiber Reinforced Concrete ◽  
Reinforced Concrete Beams ◽  
Wire Mesh ◽  
Strength Concrete ◽  
Strength And Deformation ◽  
Normal Strength ◽  
Concrete Elements

In resent years several attempts were undertaken to repair damaged reinforced concrete structures. Studies on the effectiveness of repaired and strengthened reinforced concrete elements which fail primarily due to formation of major flexural cracks are same what limited for normal strength concrete (NSC) and very limited for high strength concrete (HSC). The overall objective of the present work is to investigate the strength and deformation characteristics in flexure of reinforced HSC and NSC beams repaired with either with concrete alone or with fiber reinforced concrete or with Welded Wire Mesh (W.W.M). From the results obtained, it was found that the beams were adequately repaired and the general mode of failure was flexural. The repaired beams had higher strength than the original beams. All repaired beams exhibited significant decrease in deflection than the original beams.

Laboratory tests on strengthening steel and concrete elements with high-strength concrete

2021 ◽  
Author(s):  
Marina Traykova ◽  
Lazar Georgiev ◽  
Emad Abdulahad ◽  
Stoyan Ivanov
Keyword(s):  
High Strength Concrete ◽  
Laboratory Tests ◽  
High Strength ◽  
Reinforced Concrete Beams ◽  
Strength Concrete ◽  
Existing Structures ◽  
Additional Layer ◽  
Orthotropic Bridge Deck ◽  
Strengthening Technique ◽  
The University

<p>In the University of Architecture, Civil Engineering and Geodesy in Sofia a research project has started in 2018 aiming to investigate the possibilities of local production and application of high- strength concrete (or even UHPFRC) for strengthening existing structures in Bulgaria. Under this project laboratory tests of steel orthotropic bridge deck specimens as well as reinforced concrete beams, strengthened with high-strength concrete are performed. All elements are strengthened with an additional layer of high-strength concrete with thickness of 50mm on top.</p><p>The results obtained from the tests are summarized in this article. Comparative analysis showing the effect of this strengthening method is also presented. At the end summary and conclusions are drawn. Future steps for enhancing and promoting this strengthening technique in Bulgaria are outlined.</p>

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