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>

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.

scholarly journals Numerical analysis of inelastic reinforced high-strength concrete beams with low reinforcement ratio

2009 ◽  
Vol 4 (1) ◽  
pp. 005-030
Author(s):  
Piotr Smarzewski
Keyword(s):  
High Strength Concrete ◽  
Concrete Beams ◽  
Constitutive Models ◽  
High Strength ◽  
Structural Materials ◽  
Reinforcement Ratio ◽  
Reinforced Concrete Beams ◽  
Flexural Behavior ◽  
Element Analysis ◽  
Strength Concrete

Numerical modelling of flexural behavior of the reinforced highstrength concrete beams with low reinforcement ratio is discussed in this paper. Modelling mechanism of failure reinforced concrete beams under static load, static deformation processes of the reinforced high-strength concrete beams with regard to the physical nonlinearities of the structural materials (i.e. concrete and reinforcement steel) were developed using finite element analysis. The comparison of the numerical and experimental results as well as theoretical solutions, were presented. The compared results indicate correctness of the constitutive models of the structural materials: concrete and reinforcing steel and effectiveness of the solution method.

scholarly journals High Strength Concrete Beams Reinforced with Hooked Steel Fibers under Pure Torsion

2022 ◽  
Vol 8 (1) ◽  
pp. 92-104
Author(s):  
Haleem K. Hussain ◽  
Mustafa Shareef Zewair ◽  
Mazin Abdulimam Ahmed
Keyword(s):  
Compressive Strength ◽  
Reinforced Concrete ◽  
High Strength Concrete ◽  
Concrete Beams ◽  
Volume Fraction ◽  
High Strength ◽  
Reinforced Concrete Beams ◽  
Pure Torsion ◽  
Fiber Volume ◽  
Strength Concrete

A study of the behavior of fibers in high-strength reinforced concrete beams is presented in this paper. Twelve reinforced concrete beams were tested under a pure torsion load. Different compressive strengths (45.2, 64.7, and 84.8 MPa) and fiber volume fractions (0, 0.25, 0.5, and 0.75) with variable spacing between transverse reinforcements have been used. It was discovered that the maximum torque of a high-strength concrete beam is increased by about 20.3, 25.6, and 27.1% when the fractional volume of fiber is increased from 0 to 0.25, 0.5 and 0.75 respectively (when the compressive strength is 45.2 MPa and the transverse reinforcement spacing is 100 mm). The test results show that the ultimate torsional strength becomes higher when the concrete compressive strength increases, and this percentage increase becomes higher with increasing steel fiber volume fraction. When the spacing between transverse reinforcements decreases from 150 to 100 mm, the ultimate torque increases by 19.9%. When the spacing between transverse reinforcements decreases from 100 to 60 mm, the ultimate torque increases by 17.0%. In these beams, the fibers’ compressive strength and volume fraction were kept constant at 45.2 MPa and 0.75, respectively. Doi: 10.28991/CEJ-2022-08-01-07 Full Text: PDF

Flexural and Shear Capacity Evaluation of Reinforced Ultra-High Strength Concrete Members with Steel Rebars

2013 ◽  
Vol 577-578 ◽  
pp. 17-20 ◽  
Author(s):  
Baek Il Bae ◽  
Hyun Ki Choi ◽  
Chang Sik Choi
Keyword(s):  
High Strength Concrete ◽  
Steel Fiber ◽  
Concrete Beams ◽  
High Strength ◽  
Fiber Reinforced Concrete ◽  
Reinforced Concrete Beams ◽  
Steel Fiber Reinforced Concrete ◽  
Strength Concrete ◽  
Ultra High Strength Steel ◽  
Normal Strength

High-strength concrete is widely used in construction field. The growth has been possible as a result of recent developments in material technology and a demand for high-strength concrete. High-strength concrete has different mechanical properties from normal-strength, as many researches mentioned about. However, the existing equations and procedures for prediction of ultra-high strength concrete are based on tests using normal-strength concrete, yet. In this study, experiments on ultra-high-strength steel fiber reinforced concrete beams with 2% volume fraction of steel fiber and 200MPa of compressive strength have been conducted. Test was conducted by two point loading with 2,000kN actuator for slender test specimen which have varied shear-span to depth ratio. Using test results with several assumptions, an empirical equation for flexural strength and shear strength of ultra-high-strength steel fiber reinforced concrete beams have been proposed.

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