scholarly journals Innovative methods of strengthening reinforced concrete structures

2018 ◽  
Vol 196 ◽  
pp. 04068
Author(s):  
Dmitry Mailyan ◽  
Darya Bogomazyuk
Keyword(s):  
Reinforced Concrete ◽  
External Force ◽  
Reinforced Concrete Structures ◽  
Test Results ◽  
Transverse Compression ◽  
Feasible Method ◽  
Strength Concrete ◽  
Innovative Methods ◽  
Diagonal Reinforcement ◽  
Relative Eccentricity

The article considers some of the most innovative methods of reinforced concrete compressed elements: strengthening of elements with the help of pre-compressed longitudinal reinforcing elements, strengthening by means of concrete padding device, of low strength concrete, to strengthen the elements by biaxial transverse compression of concrete and method is to strengthen the elements with a pre-stretched diagonal reinforcement. The test results on deformation and rigidity of compressed reinforced concrete pillars are given. For each variant of rack reinforcement, depending on their flexibility and the relative eccentricity of the external force, the most technologically and economically feasible method of amplification is proposed.

Seismic Rehabilitation of Beam-Column Joints Using FRP Sheets and Buckling Restrained Braces

2013 ◽  
Vol 479-480 ◽  
pp. 1170-1174
Author(s):  
Hee Cheul Kim ◽  
Dae Jin Kim ◽  
Min Sook Kim ◽  
Young Hak Lee
Keyword(s):  
Shear Strength ◽  
Reinforced Concrete ◽  
Energy Dissipation ◽  
Seismic Performance ◽  
Reinforced Concrete Structures ◽  
Test Results ◽  
Seismic Rehabilitation ◽  
Buckling Restrained Braces ◽  
Column Joint ◽  
Energy Dissipation Capacity

The purpose of this study was to evaluate seismic performance of rehabilitated beam-column joint using FRP sheets and Buckling Restrained Braces (BRBs) and provide test data related to rehabilitated beam-column joints in reinforced concrete structures. The seismic performance of total six beam-column specimens is evaluated under cyclic loadings in terms of shear strength, effective stiffness, energy dissipation and ductility. The test results showed wrapping FRP sheets can contribute to increase the effect of confinement and the crack delay. Also retrofitting buckling restrained braces (BRBs) can improve the stiffness and energy dissipation capacity. Both FRP sheets and BRBs can effectively improve the strength, stiffness and ductility of seismically deficient beam-column joints.

Study on Seismic Behavior of Vertical Connection in Prefabricated Reinforced Concrete Structures

2011 ◽  
Vol 250-253 ◽  
pp. 1385-1394
Author(s):  
Guo Hua Song ◽  
Dong Wei Wang ◽  
Bing Kang Liu
Keyword(s):  
Reinforced Concrete ◽  
Seismic Behavior ◽  
Concrete Structures ◽  
Shear Resistance ◽  
Repeated Loading ◽  
Reinforced Concrete Structures ◽  
Test Results ◽  
Dowel Action ◽  
Cycle Loading ◽  
Good Agreement

The paper attempts to research the seismic behavior and mechanical mechanisms under repeated low-cycle loading of vertical connections in prefabricated reinforced concrete structures. Eighteen specimens were designed and tested, the test process and the mechanical mechanisms are studied, the seismic behavior of connections is analyzed, and the shear resistance formulas are proposed. The theoretical values based on proposed formulas are good agreement with test results. Under repeated loading, the shear resistance decreases, the connection ductility increases with connecting bar, but decreases with connection width. However, all the connections fail crisply with poor ductility. At sudden-cracking, the shear resistance increases with connecting bar, but changes nonlinearly with connection width. The resistance is composed of attributions of mechanism of diagonal-compressive column (MDCC) and mechanism of compressive friction action (MCFA). After sudden-cracking, the shear resistance is provided by weakened MDCC and dowel action of connecting bars (DACB). It increases with connecting bar and connection width.

scholarly journals The Mechanical Properties of Centrifuged Concrete in Reinforced Concrete Structures

2020 ◽  
Vol 10 (10) ◽  
pp. 3570
Author(s):  
Romualdas Kliukas ◽  
Ona Lukoševičienė ◽  
Arūnas Jaras ◽  
Bronius Jonaitis
Keyword(s):  
Mechanical Properties ◽  
Reinforced Concrete ◽  
Concrete Strength ◽  
Concrete Structures ◽  
High Strength ◽  
Reinforcement Ratio ◽  
Transverse Reinforcement ◽  
Reinforced Concrete Structures ◽  
Test Results ◽  
Moduli Of Elasticity

This article explores the influence of transverse reinforcement (spiral) and high-strength longitudinal reinforcements on the physical-mechanical properties of centrifuged annular cross-section elements of concrete. The test results of almost 200 reinforced, and over 100 control elements are summarizing in this article. The longitudinal reinforcement ratio of samples produced in the laboratory and factory varied from 1.0% to 6.0%; the transverse reinforcement ratio varied from 0.25% to 1.25%; the pitch of spirals varied from 100 mm to 40 mm and the concrete strength varied from 25 MPa to 60 MPa. Experimental relationships of coefficients for concrete strength, moduli of elasticity and limits of the longitudinal strain of centrifuged concrete in reinforced concrete structures in short-term concentrically compression were proposed.

Experimental Study on Compressive Bearing Capacity of High Strength Concrete-Filled Steel Tube Composite Columns

2011 ◽  
Vol 368-373 ◽  
pp. 410-414 ◽  
Author(s):  
Hong Zhen Kang ◽  
Lei Yao ◽  
Xi Min Song ◽  
Ying Hua Ye
Keyword(s):  
Compressive Strength ◽  
Reinforced Concrete ◽  
High Strength Concrete ◽  
High Strength ◽  
Steel Tube ◽  
Test Results ◽  
Concrete Filled Steel Tube ◽  
Composite Columns ◽  
Strength Concrete ◽  
Axial Compressive Strength

To study axial compressive strength of high strength concrete-filled steel tube composite columns, tests of 18 specimens were carried out. Parameters of the specimens were the confinement index of concrete-filled steel tube, the cubic strength and the stirrup characteristic value of concrete outer of steel tube. Test results show that the concrete-filled steel tube and the reinforced concrete deformed simultaneously in the axial direction before and at the peak value of axial compressive force; after failure of the reinforced concrete, the concrete-filled steel tube can still bear the axial load and deformation; the main influential factors of axial compressive capacity are confinement index, the cubic strength and the stirrup characteristic value of concrete outer of steel tube. The accuracy of the formula of axial compressive strength of composite columns provided by CECS 188:2005 is proved by the test results of this paper.

Magnetoelastic Measurements of Steel Stress under Uniaxial Loading

2006 ◽  
Vol 321-323 ◽  
pp. 377-380 ◽  
Author(s):  
Hong C. Rhim ◽  
Bo Hwan Oh ◽  
Hyo Seon Park
Keyword(s):  
Reinforced Concrete ◽  
Concrete Structures ◽  
Uniaxial Loading ◽  
Magnetic Response ◽  
Reinforced Concrete Structures ◽  
Test Results ◽  
Traditional Technique ◽  
Steel Bar ◽  
Steel Bars ◽  
Different Diameters

An attempt has been made to measure existing steel stress using magnetoelasticity. A device has been developed and used for the measurement of magnetism in response to the deformation of a steel bar. The proposed technique can be used for the assessment of existing reinforced concrete structures by the measurements of steel stress embedded inside concrete. A traditional technique requires to break the existing steel bar to measure existing strain. However, the proposed technique is developed to measure the stress without damaging the steel bar. A successful application of magnetoelasticity depends on the establishment of relationship between elastic and magnetic response due to loading. To investigate the correlation between the two, steel bars are loaded in tension under uniaxial loading while the magnetic reading is recorded. Based on the test results, equations are suggested to predict stress for steel bars with different diameters.

scholarly journals Analysis of confined masonry with Strut and Tie models

2020 ◽  
Vol 323 ◽  
pp. 02002
Author(s):  
Łukasz Drobiec ◽  
Wojciech Mazur ◽  
Tomasz Rybarczyk
Keyword(s):  
Reinforced Concrete ◽  
Full Scale ◽  
Masonry Walls ◽  
Reinforced Concrete Structures ◽  
Masonry Structures ◽  
Test Results ◽  
Confined Masonry ◽  
Good Compliance ◽  
Strut And Tie ◽  
Calculation Results

Strut & Tie (S-T) models are used quite commonly for the analysis of reinforced concrete structures and in the calculation of masonry structures. Creating the S-T model of the confined masonry is slightly different from models of reinforced concrete or models of classic masonry structures. These models should take into account different stiffness of concrete and masonry. This article proposes a Strut & Tie model for the analysis of confined masonry. The results of calculations were compared with the results of tests of full scale masonry walls with and without opening. Good compliance of the calculation results of S-T models with the test results was obtained.

scholarly journals Bond Strengths of Geopolymer and Cement Concretes

2010 ◽  
Vol 69 ◽  
pp. 143-151 ◽  
Author(s):  
Prabir Sarker
Keyword(s):  
Reinforced Concrete ◽  
Bond Strength ◽  
Concrete Cover ◽  
Reinforced Concrete Structures ◽  
Geopolymer Concrete ◽  
Reinforcing Steel ◽  
Test Results ◽  
Reinforcing Bars ◽  
Pull Out ◽  
Bar Diameter

Geopolymer is an inorganic alumino-silicate product that shows good bonding properties. Geopolymer binders are used together with aggregates to produce geopolymer concrete which is an ideal building material for infrastructures. A by-product material such as fly ash is mixed together with an alkali to produce geopolymer. Current research on geopolymer concrete has shown potential of the material for construction of reinforced concrete structures. Structural performance of reinforced concrete depends on the bond between concrete and the reinforcing steel. Design provisions of reinforced concrete as a composite material are based on the bond strength between concrete and steel. Since geopolymer binder is chemically different from Ordinary Portland Cement (OPC) binder, it is necessary to understand the bond strength between geopolymer concrete and steel reinforcement for its application to reinforced concrete structures. Pull out test is commonly used to evaluate the bond strength between concrete and reinforcing steel. This paper describes the results of the pull out tests carried out to investigate the bond strength between fly ash based geopolymer concrete and steel reinforcing bars. Beam end specimens in accordance with the ASTM Standard A944 were used for the tests. In the experimental program, 24 geopolymer concrete and 24 OPC concrete specimens were tested for pull out. The concrete compressive strength varied from 25 to 55 MPa. The other test parameters were concrete cover and bar diameter. The reinforcing steel was 500 MPa steel deformed bars of 20 mm and 24 mm diameter. The concrete cover to bar diameter ratio varied from 1.71 to 3.62. It was found from the test results that the failure occurred by splitting of concrete in the region bonded with the steel bar, in both geopolymer and OPC concrete specimens. Comparison of the test results shows that geopolymer concrete has higher bond strength than OPC concrete. This suggests that the existing design equations for bond strength of OPC concrete with steel reinforcing bars can be conservatively used for calculation of bond strength of geopolymer concrete.

scholarly journals Experimental Study of High-Strength Concrete-Steel Plate Composite Shear Walls

2019 ◽  
Vol 9 (14) ◽  
pp. 2820 ◽  
Author(s):  
Dongqi Jiang ◽  
Congzhen Xiao ◽  
Tao Chen ◽  
Yuye Zhang
Keyword(s):  
Experimental Study ◽  
Reinforced Concrete ◽  
High Strength Concrete ◽  
Steel Plate ◽  
Shear Walls ◽  
High Strength ◽  
Lateral Load ◽  
Test Results ◽  
Strength Concrete ◽  
Composite Shear

Shear walls are effective lateral load resisting elements in high-rise buildings. This paper presents an experimental study of the seismic performance of a composite shear wall system that consists of high-strength concrete walls with the embedded steel plate. Two sets of wall specimens with different aspect ratios (height/width, 1.5 and 2.7) were constructed and tested under quasi-static reversed cyclic loading, including five reinforced concrete shear walls (RCSW) and six reinforced concrete-steel plate shear walls (RCSPSW). The progression of damage, failure modes, and load-displacement responses of test specimens were studied and compared based on experimental observations. The test results indicated that high-strength (HS) RCSPSW system showed superior lateral load strength and acceptable deformation capability. The axial compressive load was found to have an indispensable effect on the ductility of both RCSW and RCSPSW, and an upper limit of axial compression ratio (0.5) is recommended for the application of HS RCSPSW in engineering practices. In addition, the design strength models were suggested for predicting the shear and flexure peak strength values of RCSPSW systems, and their applicability and reliability were verified by comparing with test results.

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