Reassessment of the flexural behavior of high-strength reinforced concrete beams under short-term loads

AbstractThis work aims at describing the behavior of high-strength reinforced concrete (HSRC) beams under short-term ultimate loads with concrete compressive strengths higher than 50 MPa. A plastic approach besides a cross sectional analysis is employed to primarily trace the nonlinear response of nineteen HSRC simply supported beams for which experimental results are available. This proposed theoretical approach is able to acceptably match the experimental data with minor overestimation of flexural moments. Closed-form expressions to evaluate ductility indexes regarding deflections and curvatures as well as plastic rotation capacities are also proposed herein. Predictions of the National Brazilian Regulation for design of concrete structures NBR6118 in terms of ultimate flexural moments are also computed for comparison. A complete assessment of ductility in which plastic rotation capacities are computed for the studied beams is also given. It is found that the flexural ductility of a member could be increased with the use of high strength concrete. The use of a maximum tension steel ratio to guarantee a minimum flexural of ductility is highlighted.

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

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.1160.25 ◽

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.

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Effect of cracking localization on the structural ductility of normal strength and high strength reinforced concrete beams with steel fibers

International Journal of Protective Structures ◽

10.1177/2041419618824609 ◽

2019 ◽

Vol 10 (4) ◽

pp. 457-469 ◽

Cited By ~ 3

Author(s):

Avraham N Dancygier ◽

Yuri S Karinski

Keyword(s):

Reinforced Concrete ◽

Transition Point ◽

Concrete Beams ◽

High Strength ◽

Reinforcement Ratio ◽

Steel Fibers ◽

Reinforced Concrete Beams ◽

Flexural Ductility ◽

Ductility Ratio ◽

The Impact

This article presents a study of cracking localization in normal and high strength concrete beams that include steel fibers and the influence of this localization on their structural ductility. It is shown that for a given fiber type and content, as the reinforcement ratio ρ decreases, the cracking localization level increases. The effect of ρ on the level of cracking localization is more pronounced for low amounts of conventional reinforcement. This range of conventional reinforcement ratio is typical of slabs and especially for the commonly thicker protective slabs. Examination of the effect of the reinforcement ratio on the flexural ductility shows that there exists a transition point below which the ductility ratio decreases with ρ. This transition point is well above the minimum reinforcement ratio, which is required in design codes for plain reinforced concrete elements. Empirical analysis of the relation between cracking localization and ductility ratio shows that up to the same transition point, as cracking localization increases, the flexural ductility decreases. Findings of this study show that the positive effect of adding fibers on enhancing the impact resistance of slabs and beams is conflicted by their negative influence on reducing the structural ductility for low reinforcement ratios, which are typical of protective slabs.

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Erratum to : FLEXURAL BEHAVIOR OF REINFORCED CONCRETE BEAMS WITH HIGH STRENGTH DEFORMED BARS

Transactions of the Japan Society of Civil Engineers ◽

10.2208/jscej1949.1965.124_52a ◽

1965 ◽

Vol 1965 (124) ◽

pp. 52a-52a

Keyword(s):

Reinforced Concrete ◽

Concrete Beams ◽

High Strength ◽

Reinforced Concrete Beams ◽

Flexural Behavior

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Flexural Behavior of High Strength Reinforced Concrete Beams by Replacement Ratio of Recycled Coarse Aggregate

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.680.230 ◽

2013 ◽

Vol 680 ◽

pp. 230-233 ◽

Cited By ~ 2

Author(s):

Yong Taeg Lee ◽

Seung Hun Kim ◽

Jong Hyeon Kim ◽

Sang Ki Baek ◽

Young Sang Cho ◽

...

Keyword(s):

Reinforced Concrete ◽

Flexural Strength ◽

Concrete Beams ◽

High Strength ◽

Reinforced Concrete Beams ◽

Flexural Behavior ◽

Recycled Aggregates ◽

Current Test ◽

Potential Applications ◽

Flexural Tests

Recently, many structures which were built about 30 years ago are watched by reconstruction. Demolished concrete is occurred in the process and these quantity increase about 10% more than the preceding year. Fortunately, recycled aggregates are produced from demolished concrete, whereas the recycled aggregates are not used often because there are not many researches which have been verified by experts or researchers about strength when reinforced concrete is made with recycled aggregates. In this paper, high strength reinforced concrete is valued with potential applications and check change of strength when it made by recycled aggregates. For this, flexural tests of 4 high strength reinforced concrete beams with recycled aggregates were performed, and the high strength reinforced concrete beams were tested within the limits such as compressive strength, flexural strength, ductility, strain, and curvature. The current test data were examined in terms of flexural strength, along with the data from previously tested reinforced concrete beams with recycled aggregates.

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