Strengthening of reinforced concrete beams constructed with substandard steel reinforcement termination

2008 ◽  
Vol 85 (1) ◽  
pp. 10-19 ◽  
Author(s):  
Yung-Chih Wang ◽  
Kai Hsu
Keyword(s):  
Reinforced Concrete ◽  
Concrete Beams ◽  
Steel Reinforcement ◽  
Reinforced Concrete Beams

scholarly journals RETROFITTING AND DACTILITY OF REINFORCED CONCRETE BEAMS USING AN EXTERNAL REINFORCEMENT METHOD

2019 ◽  
Vol 3 (2) ◽  
pp. 135
Author(s):  
Novita Ike Triyuliani ◽  
Sri Murni Dewi ◽  
Lilya Susanti
Keyword(s):  
Reinforced Concrete ◽  
Ultimate Load ◽  
Concrete Beams ◽  
Concrete Block ◽  
Steel Reinforcement ◽  
Reinforced Concrete Beams ◽  
Building Structures ◽  
Average Increase ◽  
External Reinforcement ◽  
Strength And Ductility

The innovations strengthening building structures are important topics. Failure in structures such as beams and columns due to time, re-functions of a building, even initial design errors that are weak or lack the safety factor of a building structure. External reinforced concrete beams are one of the beams currently being developed. It is a concrete block with reinforcement of steel reinforcement on the outer (external) of the beam. This study aims to determine the index of increasing beam strength and ductility after retrofitting external steel reinforcement, which has the dimension of beams 15 x 15 x 100 cm, repeating 12 pcs, with external reinforcement each 6 pcs 2Ø6 and 3Ø6. The results from this study are an increasing the index of beam flexural strength after retrofit with external steel reinforcement. Meanwhile, beams after retrofit with 2Ø6 external steel have an average increase index of 1.25 and 1.21 while for external steel 3Ø6 are 1.29 and 1.60 respectively. The ductility depends on the value of ultimate load and maximum deflection that occurs, where the ductility value for the comparison of each specimen experiences a reduction in the average ductility value with 2Ø6 external steel which is 37.74% and 70.95% while with 3Ø6 external steel is 61,65% and 60.62%. Berbagai inovasi upaya peningkatan kekuatan struktur bangunan telah menjadi bahasan yang penting. Kegagalan pada struktur seperti balok dan kolom karena umur, alih fungsi suatu bangunan, bahkan kesalahan desain awal yang lemah atau kurang memenuhi faktor keamanan suatu struktur bangunan. Balok beton bertulangan eksternal adalah salah satu balok yang sedang dikembangkan pada saat ini, yaitu balok beton dengan perkuatan tulangan baja di sisi terluar (eksternal). Penelitian ini bertujuan untuk mengetahui indeks peningkatan kekuatan balok dan daktilitas setelah dilakukan perbaikan menggunakan tulangan baja eksternal, dengan dimensi balok 15 × 15 × 100 cm berulang 12 buah, penambahan tulangan baja eksternal masingmasing 6 buah 2Ø6 dan 3Ø6. Hasil yang didapat dari penelitian ini adalah indeks peningkatan kekuatan lentur balok setelah dilakukan perbaikan menggunakan tulangan baja eksternal. Dimana balok setelah dilakukan perbaikan dengan baja eksternal 2Ø6 memiliki indeks peningkatan rata-rata 1,25 dan 1,21 sedangkan untuk baja eksternal 3Ø6 masing-masing 1,29 dan 1,60. Daktilitas tergantung dari nilai beban ultimit dan lendutan maksimum yang terjadi, dimana nilai daktilitas untuk perbandingan tiap benda uji mengalami reduksi nilai daktilitas rata-rata dengan baja eksternal 2Ø6 yaitu sebesar 37,74% dan 70,95% sedangkan dengan baja eksternal 3Ø6 sebesar 61,65% dan 60,62%.

scholarly journals The effects of steel reinforcement corrosion on the flexural capacity and stiffness of reinforced concrete beams

2021 ◽  
Author(s):  
Timothy A Joyce
Keyword(s):  
Reinforced Concrete ◽  
Concrete Beams ◽  
Chloride Ion ◽  
Steel Reinforcement ◽  
Reinforced Concrete Beams ◽  
Reinforcement Corrosion ◽  
Flexural Capacity ◽  
Ion Content ◽  
Sharp Drop ◽  
Low Degrees

This study is an attempt to derive a relationship between steel reinforcement corrosion and the coinciding loss of flexural strength. The corrosion of the steel was isolated in the flexural region in order to eliminate contributions from stirrup corrosion and loss of bond within the development length. It was determined that the flexural capacity of reinforced concrete beams decreased as the rate of corrosion increased. In addition to the study of flexural capacity, the prediction of the flexural behaviour of corroded beams was studied through the stiffness effects of reinforcement corrosion. The stiffness study indicated a sharp drop in stiffness at relatively low degrees of corrosion, followed by a slower decline at increasing levels of corrosion. Mass loss, crack width and chloride ion content were examined as indicators of degree of corrosion. These relationships are an essential step in developing an effective model for the performance of corroded reinforced concrete beams in the future.

scholarly journals Limiting Reinforcement Ratios for Hybrid GFRP/Steel Reinforced Concrete Beams

2021 ◽  
Vol 11 (1) ◽  
pp. 01-11
Author(s):  
Duy Phan Nguyen ◽  
Viet Quoc Dang
Keyword(s):  
Experimental Data ◽  
Reinforced Concrete ◽  
Concrete Beams ◽  
Steel Reinforcement ◽  
Reinforcement Ratio ◽  
Reinforced Concrete Beams ◽  
Equilibrium Equations ◽  
Steel Reinforced Concrete ◽  
Glass Fiber Reinforced ◽  
Load Carrying

In this work, a theoretical approach is proposed for estimating the minimum and maximum reinforcement ratios for hybrid glass fiber reinforced polymer (GFRP)/steel-reinforced concrete beams to prevent sudden and brittle failure as well as the compression failure of concrete before the tension failure of reinforcements. Equilibrium equations were used to develop a method for determining the minimum hybrid GFRP/steel reinforcement ratio. A method for determining the maximum hybrid GFRP/steel reinforcement ratio was also developed based on the equilibrium of forces of the balanced failure mode. For estimating the load-carrying capacity of concrete beams reinforced with hybrid GFRP/steel, less than the minimum and more than the maximum reinforcement ratio is recommended. Comparisons between the proposed expressions, experimental data, and available test results in the literature shows good agreement between the theoretical and experimental data, with a maximum discrepancy of 7%.

scholarly journals THE PROPERTIES OF PITTING CORROSION OF STEEL REINFORCEMENT OF REINFORCED CONCRETE BEAMS

2017 ◽  
Vol 2 (3) ◽  
pp. 32-36
Author(s):  
Дронов ◽  
Andrey Dronov
Keyword(s):  
Reinforced Concrete ◽  
Pitting Corrosion ◽  
Concrete Beams ◽  
Concrete Structures ◽  
Steel Reinforcement ◽  
Reinforced Concrete Beams ◽  
Reinforced Concrete Structures ◽  
Damage Distribution ◽  
Chloride Environment ◽  
Corrosion Of Steel

Two types of steel reinforcement depassivation process: carbonation of concrete and chloride penetration are considered in the article. The comparison between the corrosion due to carbonation of concrete and the chloride-induced corrosion was carried out. It was found out, that chlorides induced corrosion is potentially more dangerous than that resulting from carbonation. Method of durable tests of reinforced concrete structures under the action of the gravitational load and the corrosive chloride environment is described in the article. The results of experimental research on reinforced concrete structures with corrosive damages to steel reinforcement are given in the article. The properties of corrosion cracking in the case of the pitting corrosion were determined. The character of corrosive damage distribution along the reinforcement bars and its effect on the strength of reinforced concrete beams were determined.

scholarly journals Influence of PVC Fiber Reinforcement on Shear Strength in Concrete Beams

2019 ◽  
Vol 7 (1) ◽  
pp. 34-43
Author(s):  
Kadhim Zuboon Nasser ◽  
Ali Abdulhasan Khalaf ◽  
Fadhil K. Idan
Keyword(s):  
Reinforced Concrete ◽  
Concrete Beams ◽  
Volume Fraction ◽  
Concrete Structures ◽  
Fiber Reinforcement ◽  
Steel Reinforcement ◽  
Reinforced Concrete Beams ◽  
Shear Reinforcement ◽  
Time Service ◽  
Before And After

This study adopted the investigation of the effect of a material that can be used as an alternative to steel reinforcement of shear in reinforced concrete beams, as the most susceptible to corrosion to which reduces the time service of the concrete structures and increase the maintenance costs is the steel reinforcement of shear for the closeness of surface of concrete. Therefor non-corroding material is needful for concrete structures and PVC fiber reinforcement is chosen. Experimentally nine reinforced concrete beams have been tested to determine the effect of PVC fiber reinforcement on the concrete beam resistance load, the load of cracks, deflection achieved and distribution with dimension of cracks. Three volume fraction ratios were taken for PVC fiber reinforcement (0, 0.25 and 0.5), which were identical to the shear reinforcement used in this research (0,0.29 and 0.54). All the concrete beams were tested with in on one program by applied a center load from the top in the middle to the failure load and the results were impressive. The specimens containing the PVC fiber reinforcement percentages achieved a remarkable increase in the crack and ultimate load of the concrete beams before and after cracks with direct effect in changing the failure type. While the deflection achieved due to the increase in PVC fiber percentage is more than the allowable deflection in the ACI Code equations of the reinforced concrete beams and more of these if the use of PVC fiber and steel reinforcement of shear together. A smaller measurement of the maximum cracks width was achieved by using advanced percentages of PVC fiber and shear reinforcement (0.5 and 0.54) respectively.

Influence of Minimum Tension Steel Reinforcement on the Behavior of Singly Reinforced Concrete Beams in Flexure

2020 ◽  
Vol 38 (7A) ◽  
pp. 1034-1046
Author(s):  
Ali ِA. Abdulsada ◽  
Raid I. Khalel ◽  
Kaiss F. Sarsam
Keyword(s):  
Compressive Strength ◽  
Reinforced Concrete ◽  
Concrete Beams ◽  
Rectangular Cross Section ◽  
Steel Reinforcement ◽  
Reinforced Concrete Beams ◽  
Concrete Compressive Strength ◽  
Minimum Reinforcement ◽  
Flexural Reinforcement ◽  
New Formula

The requirements of minimum flexural reinforcement in the last decades have been a reason for controversy. The structural behavior of beams in bending is the best way of investigating and evaluating the minimum reinforcement in flexure. For this purpose, twelve singly reinforced concrete beams with a rectangular cross-section of (125 mm) width by (250 mm) height and (1800 mm) length were cast and tested under two-point loads up to failure. These beams were divided into three groups with different compressive strengths (25, 50, and 80 MPa). Each group consists of four beams with different amounts of tension steel reinforcement approximately equal to (0% Asmin, 50% Asmin, 100% Asmin and 150% Asmin), two bar diameters (Ø6 mm and Ø8 mm) were used as the longitudinal tension reinforcement with different yield and ultimate strengths, the minimum amount of reinforcement required is calculated based on ACI 318M-2014 code. The results show that for the reinforced concrete beams, the flexural reinforcement in NSC beams increases the first cracking load and the increment increased with an increasing amount of reinforcement, while for HSC beams the increasing in first cracking load are very little when the quantity of reinforcement less than the minimum flexural reinforcement and increased with the increasing amount above the minimum flexural reinforcement. The equation of ACI 318M-14 code gives adequate minimum flexural reinforcement for NSC and overestimate value for HSC up to (83 MPa), A new formula is proposed for HSC rectangular beams up to (90 MPa) concrete compressive strength by reducing the equation of ACI 318M-14 code for minimum flexural reinforcement by a factor depending on concrete compressive strength.  

Analysis of reinforced concrete beams strengthened in flexure with composite laminates

1999 ◽  
Vol 26 (5) ◽  
pp. 646-654 ◽  
Author(s):  
C Nitereka ◽  
K W Neale
Keyword(s):  
Finite Element ◽  
Reinforced Concrete ◽  
Composite Laminates ◽  
Composite Structures ◽  
Composite Laminate ◽  
Concrete Beams ◽  
Steel Reinforcement ◽  
Nonlinear Finite Element ◽  
Reinforced Concrete Beams ◽  
Reinforced Composite

The structural behaviour of reinforced concrete beams strengthened in flexure by means of externally bonded fibre reinforced composite laminates is simulated numerically using a nonlinear finite element layered model. The full-bond assumption between the composite laminate, steel reinforcement, and the concrete is assumed, and shear deformations are neglected. Interlayer compatibility is achieved by imposing the same displacements at the interfaces of adjacent layers. The concrete is assumed to be nonlinear in compression and to exhibit a post-cracking tension-stiffening behaviour in tension. The behaviour of the steel reinforcement is modelled as elastic-plastic, while that for the composite laminate is linear elastic using an equivalent elastic modulus obtained from the so-called "classical lamination theory" of composite structures. An incremental, iterative displacement-control numerical analysis is developed. The finite element code is validated using published test results for conventional reinforced concrete beams, as well as for beams strengthened with composite laminates. A comparison of the numerical and experimental curves shows very good agreement. The effects of various parameters on the behaviour of composite-strengthened concrete beams are examined.Key words: reinforced concrete beams, fibre reinforced composite strengthening, nonlinear finite element analysis.

scholarly journals Behavior of reinforced concrete beams reinforced with GFRP bars

2008 ◽  
Vol 1 (3) ◽  
pp. 285-295 ◽  
Author(s):  
D. H. Tavares ◽  
J. S. Giongo ◽  
P. Paultre
Keyword(s):  
Reinforced Concrete ◽  
Structural Engineering ◽  
Concrete Beams ◽  
Steel Reinforcement ◽  
Reinforced Concrete Beams ◽  
Fiber Reinforced Polymer ◽  
Tension Force ◽  
Fiber Reinforced ◽  
Gfrp Bars ◽  
Reinforced Polymer

The use of fiber reinforced polymer (FRP) bars is one of the alternatives presented in recent studies to prevent the drawbacks related to the steel reinforcement in specific reinforced concrete members. In this work, six reinforced concrete beams were submitted to four point bending tests. One beam was reinforced with CA-50 steel bars and five with glass fiber reinforced polymer (GFRP) bars. The tests were carried out in the Department of Structural Engineering in São Carlos Engineering School, São Paulo University. The objective of the test program was to compare strength, reinforcement deformation, displacement, and some anchorage aspects between the GFRP-reinforced concrete beams and the steel-reinforced concrete beam. The results show that, even though four GFRP-reinforced concrete beams were designed with the same internal tension force as that with steel reinforcement, their capacity was lower than that of the steel-reinforced beam. The results also show that similar flexural capacity can be achieved for the steel- and for the GFRP-reinforced concrete beams by controlling the stiffness (reinforcement modulus of elasticity multiplied by the bar cross-sectional area - EA) and the tension force of the GFRP bars.

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