Strengthening and Characterization of Existing Reinforced Concrete Beams for Flexure by Effective Utilization of External Steel Elements

2020 ◽  
pp. 136943322095061
Author(s):  
Akhtar Gul ◽  
Bashir Alam ◽  
Wisal Ahmed ◽  
Nauman Wahab ◽  
Khan Shahzada ◽  
...  
Keyword(s):  
Reinforced Concrete ◽  
Shear Failure ◽  
Concrete Beams ◽  
Concrete Cover ◽  
Reinforced Concrete Beams ◽  
Flexural Capacity ◽  
Steel Bars ◽  
External Strengthening ◽  
Steel Angles ◽  
Control Samples

Strengthening of structural members is a common practice around the world that may arise due to deterioration of concrete with age or upgradation of design code. This paper aims to elucidate a technique used for strengthening of the reinforced concrete beam for flexural capacity by using externally welded steel angles and steel bars. For this motive, three beams were strengthened with external steel angles and three with external steel bars. The external strengthening steel elements were attached at the bottom of the beam with shear reinforcement. Control samples without external steel angles and steel bars for comparison purposes were also prepared. All reinforced concrete beams were first constructed using a concrete ratio of 1:2:4, and then external steel elements were added to existing flexural reinforcement by using a fillet weld with tee joints having thickness and length of 5/16" (7.9 mm) and 6" (152.4 mm), respectively. Fourth point loading criteria were used to investigate the flexural capacity of beams in positive bending. All beams were designed strong enough in shear, to resist the ultimate loads without shear failure. Test results indicated that beams strengthened with this technique have an average increase of 238% with steel angles and 106% with steel bars, in load-carrying capacity than control samples. Strengthened beams showed a uniform crack pattern. Moreover, the concrete cover made a good bond with existing concrete and was strong enough to withstand ultimate loads. Conclusively, the steel angles and steel bars can be used as an external strengthening material, to enhance the flexural capacity of reinforced concrete beams.

Implication of Unbondedness in Reinforced Concrete Beams

2012 ◽  
Vol 587 ◽  
pp. 36-41 ◽  
Author(s):  
S.F.A. Rafeeqi ◽  
S.U. Khan ◽  
N.S. Zafar ◽  
T. Ayub
Keyword(s):  
Shear Strength ◽  
Reinforced Concrete ◽  
Failure Mode ◽  
Shear Failure ◽  
Concrete Beams ◽  
Experimental Results ◽  
Reinforced Concrete Beams ◽  
Rc Beams ◽  
Flexural Capacity ◽  
Flexural Reinforcement

In this paper, behaviour of nine (09) RC beams (including two control beams) after unbonding and exposing flexural reinforcement has been studied which were intentionally designed and detailed to observe flexural and shear failure. Beams have been divided into three groups based on failure mode and unbounded and exposed reinforcement. Beams have been tested under two-point loading up to failure. Experimental results are compared in terms of beam behaviour with respect to flexural capacity and failure mode which revealed that the exposed reinforcement does not altered flexural capacity significantly and unbondedness positively influences shear strength; however, serviceability performance of beams with unbonded and exposed reinforcement is less.

scholarly journals Flexural capacity of RC beams strengthened with near-surface mounted steel bars

2021 ◽  
Vol 331 ◽  
pp. 05009
Author(s):  
Rendy Thamrin ◽  
Zaidir Zaidir
Keyword(s):  
Reinforced Concrete ◽  
Concrete Beams ◽  
Peak Load ◽  
Reinforced Concrete Beams ◽  
Flexural Capacity ◽  
Near Surface ◽  
Steel Bars ◽  
Near Surface Mounted ◽  
Monotonic Loads ◽  
Test Result

An experimental study carried out to observe the flexural capacity of reinforced concrete beams strengthened with Near Surface Mounted (NSM) steel bars is presented. The test was carried out on nine concrete beams. All tested beams were subjected to two-point monotonic loads. The ratio of longitudinal reinforcement (1%, 1.4%, and 2.4%) and NSM bars (1D16 and 2D16) were used as test variables. It was found from the test result that NSM steel bars significantly increase the flexural capacity of reinforced concrete beams. However, the strengthened beams failed in brittle mode, as indicated by a sudden drop of beams capacity. An analytical study was also conducted to obtain the flexural response of the specimens through all ranges of elastic and post-peak load. The prediction of the flexural capacity of the beams compares well with the test result.

scholarly journals Rehabilitation of Shear-Damaged Reinforced Concrete Beams Using Self-Compacting Concrete Jacketing

2012 ◽  
Vol 2012 ◽  
pp. 1-12 ◽  
Author(s):  
Constantin E. Chalioris ◽  
Constantin N. Pourzitidis
Keyword(s):  
Reinforced Concrete ◽  
Shear Failure ◽  
Concrete Beams ◽  
Reinforced Concrete Beams ◽  
Test Results ◽  
Self Compacting Concrete ◽  
Four Point Bending ◽  
Steel Bars ◽  
Bottom Width ◽  
Bending Loading

The application of a reinforced self-compacting concrete jacket for the structural rehabilitation of shear damaged reinforced concrete beams is experimentally investigated. Five beams were constructed and subjected to monotonic loading in order to exhibit shear failure. The damaged specimens were restored using relatively thin reinforced jackets and retested by the same four-point bending loading. The self-compacting concrete jacket applied, encasing the bottom width and both vertical sides of the initially tested beams (U-formed jacketing), has a small thickness (25 mm) and includes small (5) steel bars and U-formed stirrups. Test results and comparisons between the experimental behaviour of the beams indicated that the examined jacketing technique is a reliable rehabilitation method since the capacity of the retrofitted beams was fully restored or ameliorated with respect to the initial specimens. Discussion of the ability of the applied jacket to enhance the overall structural performance of the examined beams and, potentially, to alter their failure mode to a more ductile one is also included. Calculations of the flexural and shear strength of the tested beams and evaluation of the monolithic factors for the capacity at yield and at ultimate of the jacketed beams were also performed and are commented on.

Analisa Pola Kegagalan Balok Beton Menggunakan GFRP Bar Tanpa Selimut Beton

2020 ◽  
Vol 24 (1) ◽  
pp. 11-16
Author(s):  
Saddam - Husein ◽  
Rudy Djamaluddin ◽  
Rita Irmawaty ◽  
Kusnadi Kusnadi
Keyword(s):  
Reinforced Concrete ◽  
Concrete Beams ◽  
Concrete Cover ◽  
Steel Reinforcement ◽  
Fiber Reinforced Polymer ◽  
Mode Analysis ◽  
Flexural Capacity ◽  
Reinforced Polymer ◽  
Glass Fiber Reinforced ◽  
Gfrp Bar

SADDAM HUSEIN. Analisa Pola Kegagalan Balok Beton Menggunakan GFRP Bar Tanpa Selimut Beton (dibimbing oleh Rudi Djamaluddin dan Rita Irmawaty) Struktur beton bertulang yang menggunakan tulangan baja pada daerah korosif, menjadi rawan terhadap kerusakan atau penurunan kekuatannya akibat korosi.Korosi pada tulangan baja merupakan salah satu faktor penyebab menurunnya kekuatan struktur beton bertulang. Salah satu material yang dikembangkan mengatasi korosi adalah penggunaan material tulangan GFRP (Glass Fiber Reinforced Polymer). Penelitian ini bertujuan untuk menganalisa kapasitas lentur dan pola kegagalan balok beton tanpa selimut dengan menggunakan material tulangan GFRP bar.   Desain penelitian merupakan eksperimental laboratorium dengan rekapitulasi sebanyak 6 sampel yang terdiri dari 2 Balok beton menggunakan tulangan baja dengan selimut beton, 2 balok beton menggunakan tulangan GFRP bar dengan selimut beton, 2 balok beton menggunakan GFRP bar tanpa selimut beton. Metode pengujian dilakukan dengan dengan pengujian lentur statik monotonik dan Analisis data menggunakan uji kondisi retak awal dan kondisi ultimit.   Hasil penelitian ini menunjukkan bahwa kapasitas lentur pada balok dengan tulangan GFRP bar lebih besar dibandingkan dengan balok tulangan baja dan mampu meningkatkan kapasitas lentur balok dalam menahan beban sebesar 39.76 %, pola kegagalan beton yang terjadi pada balok tulangan baja mengalami kegagalan lentur tekan ditandai dengan retakan yang terjadi pada sisi tertekan dan membentuk retakan tegak dengan sumbu netral beton yang tertekan, sedangkan pada balok beton tulangan GFRP tanpa selimut mengalami kegagalan keruntuhan tekan geser dengan kondisi tulangan berdeformasi (bi-linear) dengan retak miring dan secara tiba-tiba menjalar menuju sumbu netral beton yang tertekan sehingga terjadilah keruntuhan secara tiba-tiba.     SADDAM HUSEIN.Failure mode analysis of concrete Beams Using GFRP rebar Without concrete cover (supervised by Rudi Djamaluddin and Rita Irmawaty)   Reinforced concrete that uses rebar steel in corrosive areas, are prone to damage or decreased strength due to corrosion. Corrosion in the steel reinforcement is one of the factors that decreasing strength of reinforced concrete. One of the materials developed to overcome corrosion is the use of GFRP (Glass Fiber Reinforced Polymer) reinforcement material. This study aims to analyze the flexural capacity and failure mode of concrete beams without concrete cover using material GFRP bar as reinforcement.   The research design was an experimental laboratory with a recapitulation of 6 samples consisting of 2 beams using steel reinforcement with concrete cover.2 concrete beams using reinforcement GFRP bar with concrete cover, 2 beams using GFRP bars without concrete cover. The  research method uses the monotonic static flexure and analyzing the data using the initial crack condition and ultimate conditions test.   The results of the research indicate the flexural capacity of the beams with GFRP bar reinforcement is higher than steel reinforcement beams and can increase 39.76% of the flexural capacity of the beams in holding loads , the failure mode analysis occurs in steel reinforcing beam experiences compressive failure. Failure was characterized  by cracks that occur on the depressing side and form an upright crack with the neutral axis of the compressed concrete, whereas in GFRP reinforced concrete beams without concrete cover, failure of shear compression with conditions of deformed reinforcement (bi-linear) with sloping cracks and suddenly spread towards the neutral axis of the compressed concrete so that there was a sudden collapse.

scholarly journals Numerical Sensing of Plastic Hinge Regions in Concrete Beams with Hybrid (FRP and Steel) Bars

Sensors ◽  
2018 ◽  
Vol 18 (10) ◽  
pp. 3255 ◽  
Author(s):  
Fang Yuan ◽  
Mengcheng Chen
Keyword(s):  
Finite Element ◽  
Reinforced Concrete ◽  
Concrete Beams ◽  
Plastic Hinge ◽  
Reinforcement Ratio ◽  
Reinforced Concrete Beams ◽  
Concrete Members ◽  
Steel Bars ◽  
Hybrid Reinforcement ◽  
Steel Hardening

Fibre-reinforced polymer (FRP)-reinforced concrete members exhibit low ductility due to the linear-elastic behaviour of FRP materials. Concrete members reinforced by hybrid FRP–steel bars can improve strength and ductility simultaneously. In this study, the plastic hinge problem of hybrid FRP–steel reinforced concrete beams was numerically assessed through finite element analysis (FEA). Firstly, a finite element model was proposed to validate the numerical method by comparing the simulation results with the test results. Then, three plastic hinge regions—the rebar yielding zone, concrete crushing zone, and curvature localisation zone—of the hybrid reinforced concrete beams were analysed in detail. Finally, the effects of the main parameters, including the beam aspect ratio, concrete grade, steel yield strength, steel reinforcement ratio, steel hardening modulus, and FRP elastic modulus on the lengths of the three plastic zones, were systematically evaluated through parametric studies. It is determined that the hybrid reinforcement ratio exerts a significant effect on the plastic hinge lengths. The larger the hybrid reinforcement ratio, the larger is the extent of the rebar yielding zone and curvature localisation zone. It is also determined that the beam aspect ratio, concrete compressive strength, and steel hardening ratio exert significant positive effects on the length of the rebar yielding zone.

The Application Research of Reinforced Concrete Multi-Ribbed Hollow Composite Slab in the Road Slab Culvert

2011 ◽  
Vol 368-373 ◽  
pp. 307-311
Author(s):  
Dong Qi Zhao ◽  
Yi Jun Tang ◽  
Hui Li ◽  
Gui Feng Song ◽  
Feng Ling Guan
Keyword(s):  
Reinforced Concrete ◽  
Concrete Beams ◽  
Concrete Cover ◽  
Reinforced Concrete Beams ◽  
Application Research ◽  
Composite Slab ◽  
The Road ◽  
High Integrity ◽  
Cover Design ◽  
Bottom Slab

Reinforced concrete cover in the road culvert cover design, in order to facilitate the construction, usually using precast reinforced concrete solid slab, but the overall cost is not low. This article researched a reinforced concrete multi-ribbed hollow composite slab, it based on the theory of reinforced concrete multi-ribbed slab structures, using a precast reinforced concrete ribbed slab as the bottom die, then poured reinforced concrete beams and panels rib ,and them constituted a whole stack of reinforced concrete ribbed hollow slab. This kind of cover, compared with the precast reinforced concrete solid cover, is not only good mechanical properties, high integrity, but also saving concrete, steel, and bottom slab appeared smooth and fine, lower construction cost.

Laboratory Fast Corrosion Test of Plain Steel Bars in Concrete Beams

2012 ◽  
Vol 535-537 ◽  
pp. 1803-1806
Author(s):  
Shun Bo Zhao ◽  
Peng Bing Hou ◽  
Fu Lai Qu
Keyword(s):  
Reinforced Concrete ◽  
Concrete Beams ◽  
Numerical Models ◽  
Concrete Strength ◽  
Reinforced Concrete Beams ◽  
Uniform Corrosion ◽  
Pure Bending ◽  
Accelerated Corrosion ◽  
Steel Bars ◽  
Bending Length

An experimental study was carried out to examine the non-uniform corrosion of plain steel bars in reinforced concrete beams partially placed in 5% sodium chloride solution under conditions of accelerated corrosion. 4 reinforced concrete beams with different concrete strength were made. The crack distributions of the beams due to pre-loads and expansion of corrosion product, and the sectional corrosion characteristics of plain steel bars are described in detail. The sectional area loss relating to mass loss and change along pure bending length of the beams are discussed. These can be used as the basis of test for further studies to build the numerical models of serviceability of corroded reinforced concrete beams.

scholarly journals Study of the reinforcement of structure members by polypropylene fibres waste

2018 ◽  
Vol 149 ◽  
pp. 01022 ◽  
Author(s):  
Khadra Bendjillali ◽  
Mohamed Chemrouk
Keyword(s):  
Reinforced Concrete ◽  
Significant Contribution ◽  
Concrete Beams ◽  
Average Diameter ◽  
Concrete Surface ◽  
Point Of View ◽  
Reinforced Concrete Beams ◽  
Polypropylene Fibres ◽  
Steel Bars ◽  
Material Durability

The valorisation of industrial waste in the field of construction became a very interesting axis of research from scientific, economic and environmental point of view. We have conducted this work to study the effect of the addition of polypropylene fibres waste on the mechanical behaviour of reinforced concrete beams subjected to a simple flexural loading, with and without transversal reinforcement. The used fibres are coming from the waste of the fabrication of domestic brushes and sweeps; they have an average diameter of 0.47 mm and a length between 40 and 60 mm. Two weight dosages of fibres are used, 0.25 and 0.5 %. The experimental results showed that the incorporation of polypropylene fibres waste into the concrete affects negatively its workability, but its flexural and compressive strength are improved. The fibers have presented a significant contribution on the shear behavior and the cracking of beams, particularly in absence of transversal bars. The waste used in this work as fibrous reinforcement has not only increased the ductility of reinforced concrete beams, but it have also provided a perfect cracking distribution on the concrete surface and it has participated in a considerable way in the reduction of cracks number and dimensions, which allows to ensure the material durability and then the structure longevity. The reinforcement of concrete beams with 0.5 % of polypropylene fibers waste with a minimal steel bars can ensure an excellent mechanical behavior in shear, as in flexion.

Analysis of Crack Patterns of 500MPa Reinforced Concrete Beams

2013 ◽  
Vol 790 ◽  
pp. 120-124
Author(s):  
Zhi Hua Li ◽  
Xiao Zu Su
Keyword(s):  
Static Loading ◽  
Crack Width ◽  
Concrete Beams ◽  
Concrete Cover ◽  
Reinforced Concrete Beams ◽  
Crack Control ◽  
Crack Patterns ◽  
Beam Depth ◽  
Steel Bars ◽  
Constant Moment

Fourting concrete beams reinforced with 500MPa longitudinal steel bars, of which 6 with skin reinforcement and 8 without skin reinforcement, were tested under two-point symmetrical concentrated static loading to investigate their crack patterns. Crack distributions in constant moment region of beams are compared. The propagation of side cracks along the beam depth is obtained. The results of this study indicate that the concrete cover of longitudinal tensile steel bars and the spacing of skin reinforcement has significant effect on crack distributions; substantial crack control in beams can be achieved if the spacing of skin reinforcement is limited to certain critical values. The curve of d-w(d is the distance between observation points of side cracks and tension face of beams, w refers to crack width at observation points) is approximately characterized by a zig-zag shape and concave-left near longitudinal tensile steel bars.

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