Analysis of Columns Strengthened using Fibre Reinforced Cementitious Matrix Jackets

2021 ◽  
Vol 9 (9) ◽  
pp. 1795-1800
Author(s):  
Fathima Azad
Keyword(s):  
Steel Plates ◽  
Structural Elements ◽  
Near Surface ◽  
Rc Structures ◽  
Cementitious Matrix ◽  
Reinforced Polymer ◽  
Externally Bonded ◽  
Fibre Reinforced Polymer ◽  
Near Surface Mounted ◽  
Strengthening Technique

Abstract: Maintenance, repair and strengthening of existing concrete structures, either reinforced or prestressed,are important activities of civil engineers. Nowadays different techniques are available for the strengthening. Various techniques were adopted for strengthening RC structures, namely, steel plates, external post tensioning, externally bonded Fibre-Reinforced Polymer (FRP), and near- surface-mounted FRP systems to increase shear and flexural capacity. During the last few decades, strengthening of concrete structural elements by fibre-reinforced polymer has become a widely used technique. But it has several disadvantages due to the epoxy resin like debonding of FRP from the concrete structure, unstable nature of the epoxy at higher temperatures etc. To overcome this, an upgraded system was introduced as an alternative for FRP known as Fibre Reinforced Cementitious Matrices (FRCM). The objective of this paper is to investigate the feasibility of Fibre-Reinforced Cementitious-Matrix materials as an alternative external strengthening technique for RC members. Columns with circular geometry were wrapped with different fibre materials using cementitious matrix. The analysis was done using ANSYS software. Keywords: RC columns, FRCM, Strengthening, fibre, ANSYS

scholarly journals Punching Strengthening of Concrete Slab-column Connections Using Near Surface Mounted (NSM) Carbon Fiber Reinforced Polymer (CFRP) Bars

2020 ◽  
pp. 1-14
Author(s):  
Ahmed H. Abdel-Kareem
Keyword(s):  
Carbon Fiber ◽  
Concrete Slab ◽  
Tensile Force ◽  
Shear Capacity ◽  
Punching Shear ◽  
Near Surface ◽  
Reinforced Polymer ◽  
Externally Bonded ◽  
Near Surface Mounted ◽  
Strengthening Technique

This paper investigates experimentally the effect of near surface mounted (NSM) carbon fiber reinforcement polymer (CFRP) bars as externally strengthening on the punching shear behavior of interior slab-column connections. Many researchers used NSM as a novel strengthening technique in various structural elements. However, the strengthening of slab-column connections using NSN is relatively new. Seven Reinforced concrete (RC) square slabs with a concentric column were tested over simply supported four sides. One control specimen was tested without strengthening, four specimens were strengthened using NSM-CFRP bar installed in pre-cut groove surrounded the column at the tension side of the slab, and two specimens were strengthened using externally bonded (EB) CFRP strips which have the same tensile force of the CFRP bars. The arrangement and the location of the strengthened materials were also test variables. The test results showed that using NSM strengthening technique significantly increased the punching shear capacity and ultimate stiffness compared to using EB strengthening technique. Where the increasing in the punching capacity and ultimate stiffness were 18% and 13-18%, respectively. Moreover, the NSM-CFRP bars greatly reduced the cracks in the punching shear zone around the columns. The measured ultimate punching shear capacity for the tested specimens showed very reasonable agreement with the calculated punching loads based on an analytical model for slab-column connections strengthened using FRP that account for its arrangement and location.  

Prestressed near-surface mounted fibre reinforced polymer reinforcement for concrete structures — a review

2013 ◽  
Vol 40 (11) ◽  
pp. 1127-1139 ◽  
Author(s):  
Raafat El-Hacha ◽  
Khaled Soudki
Keyword(s):  
Near Surface ◽  
Rc Structures ◽  
Reinforced Polymer ◽  
External Prestressing ◽  
Fibre Reinforced Polymer ◽  
Frp Reinforcement ◽  
Near Surface Mounted ◽  
Long Term Performance ◽  
Term Performance

The specialized application of prestressing the near-surface mounted (NSM) fibre reinforced polymer (FRP) reinforcement for strengthening reinforced concrete (RC) structures combines the benefits of the FRP reinforcement with the advantages associated with external prestressing. By applying a prestress to the NSM FRP the material is used more efficiently since a greater portion of its tensile capacity is employed. This paper presents a comprehensive review on the performance of RC members strengthened using prestressed NSM FRP reinforcement. Several techniques and anchorage systems developed to prestress the NSM FRP are presented. The static flexural and fatigue performance of RC beams strengthened using prestressed NSM FRP in comparison to non-prestressed NSM is presented. Research on the long-term performance under freeze–thaw exposures and sustained loading is also presented.

Comparative study on the flexural strengthening of RC beams using EB CFRP sheets, NSM CFRP bars, P-SWRs, and their combinations

2020 ◽  
pp. 136943322097172
Author(s):  
Yihua Zeng ◽  
Xinghua Li ◽  
Amira Hamdy Ali Ahmed ◽  
Gang Wu
Keyword(s):  
Steel Wire ◽  
Experimental Investigations ◽  
Near Surface ◽  
Flexural Strengthening ◽  
Wire Ropes ◽  
Cfrp Sheets ◽  
Externally Bonded ◽  
Near Surface Mounted ◽  
Strengthening Technique ◽  
Space Requirements

The externally bonded (EB) carbon fiber reinforced polymer (CFRP), near-surface-mounted (NSM) CFRP and the prestressed steel wire ropes (P-SWRs) has been proven to be feasible and reliable flexural strengthening methods for concrete structures. However, debonding issues in EB CFRP sheets (or NSM CFRP bars) and space requirements for edge and spacing clearance of NSM CFRP bars (or P-SWRs) has limited the application of these three strengthening techniques. Therefore, the combinations of these methods need to be investigated and clarified. In this paper, experimental investigations on the flexural performances of seven concrete beams are presented, in which three of the beams were separately strengthened with EB CFRP sheets, NSM CFRP bars, and P-SWRs, respectively, and three of the beams were combinedly strengthened with two of the three techniques. Test results demonstrated that the flexural performances of beams strengthened with the combination with EB CFRP sheets, NSM CFRP bars, and P-SWRs are between the flexural performances of the beams strengthened with the corresponding individual strengthening techniques. It is found that the P-SWRs is favorable for combinations. In case the P-SWRs was combined with EB CFRP sheets or NSM CFRP bars for strengthening, the cracking load was increased to more than 230% and the maximum ultimate load-bearing capacity was increased to 150% when compared with the control beam. The debonding which occurred more or less in the beams strengthened with EB CFRP sheets or NSM CFRP bars or their combination was successfully eliminated by using the combination strengthening technique with P-SWRs. Also, the combination of P-SWRs with EB CFRP sheets or NSM CFRP bars is also favorable to improve the ductility of strengthened beams.

STRENGTHENING OF PRESTRESSED HOLLOW CORE SLABS WITH OPENINGS USING NSM-CFRP STRIPS

2016 ◽  
Vol 3 (1) ◽  
Author(s):  
Karam Mahmoud ◽  
Steven Foubert ◽  
Ehab El-Salakawy
Keyword(s):  
Original Structure ◽  
Test Results ◽  
Hollow Core ◽  
Near Surface ◽  
Reinforced Polymer ◽  
Industrial Buildings ◽  
Near Surface Mounted ◽  
Parking Garages ◽  
Strengthening Technique

Precast, prestressed, hollow-core (HC) slabs are extensively used in many structures such as parking garages, commercial and industrial buildings. It is common for such structures to undergo changes while still in service, which may result in a reduction of their strength. One of these changes is to add in-situ openings at different locations along the slab to accommodate services such as intake/exhaust ducts or utility conduits. Near surface mounted (NSM) strengthening technique has proved to be an adequate technique that can be employed to restore or enhance the performance of the original structure. In this paper, the effect of openings and the efficiency of using NSM carbon fiber reinforced polymer (CFRP) strips as strengthening technique are investigated. A total of three full-scale prestressed HC slabs were tested; one without opening, one with an opening in the pure flexural zone and one with strengthened opening. Test results showed the presence of opening along the flexure span had a significant adverse effect on the post-cracking flexural stiffness, cracking load and the ultimate capacity of the slab. However, strengthening the opening with two strips of NSM-CFRP effectively enhanced the post-cracking stiffness, increased the ductility of the member and restored the flexural strength deficit incurred as a result of cutting the opening, and provided a net increase in flexural capacity.

Comparison of Various Techniques for Flexural Strengthening of Thin Concrete Members Using Continuous Carbon Fibers

2015 ◽  
Vol 1120-1121 ◽  
pp. 1458-1462
Author(s):  
Andrej Ivanič ◽  
Samo Lubej
Keyword(s):  
Carbon Fibers ◽  
Flexural Stress ◽  
Near Surface ◽  
Flexural Strengthening ◽  
Flexural Performance ◽  
Concrete Members ◽  
Modes Of Failure ◽  
Externally Bonded ◽  
Near Surface Mounted ◽  
Strengthening Technique

This paper deals with flexural performance of thin concrete members reinforced with continuous carbon fibers in the form of filament yarns. The laboratory specimens were tested under static loading conditions to investigate the effects of three different strengthening techniques on flexural stress, mid-span deflection and modes of failure. The specimens were strengthened in flexure using carbon fiber yarns as near-surface mounted, externally bonded and placed in the geometric center of the specimen, respectively. Based on this investigation, the advantages and shortcomings of individually strengthening technique can be drawn.

COMPARATIVE STUDY ON THEORETICAL MODELS AND DESIGN CODES FOR THE SHEAR CONTRIBUTION OF NSM FRP BARS IN RC BEAMS

2016 ◽  
Vol 78 (5) ◽  
Author(s):  
Abdul Aziz Abdul Samad ◽  
Noridah Mohamad ◽  
Josef Hadipramana ◽  
Mohamad Razi Ashaari Amiruddin
Keyword(s):  
Comparative Study ◽  
Theoretical Models ◽  
Design Codes ◽  
Rc Beams ◽  
Near Surface ◽  
Reinforced Polymer ◽  
Close Observation ◽  
Fibre Reinforced Polymer ◽  
Near Surface Mounted ◽  
Experimental Findings

This paper presents a comparative study on various theoretical models and design codes for the shear contribution of Near-Surface Mounted (NSM) using Fibre Reinforced Polymer bars to reinforced concrete (RC) beams. Theoretical models from De Lorenzis and A. Nanni, Anwarul Islam and Diaz and Barros, and ACI440.1R-06 and CSA-S806 design codes were selected. All the equations were compared by integrating experimental parameters from Rizzo and De Lorenzis, and Cisneros D. et al. From analysis, it was observed that the theoretical models shows substantial differences by underestimating the experimental findings of Rizzo and De Lorenzis from -68% to -38%. Similarly with Cisneros experimental work, the three theoretical models also produces large differences ranging from -73% to +41%. The analysis from the two design codes from ACI440.1R-06 and CSA-S806 also resulted with both design codes having significant differences ranging from -60% to +48%. However, from close observation, Dias and Barros theoretical model showed more accuracy by having a difference of just -4% with ACI440.1R-06 design code giving a much higher but acceptable difference of +26% compared to CSA-S806 at -60%. 

Modification and Strengthening of a Characteristic Reinforced Concrete Building in Patras, Greece

2020 ◽  
pp. 21-41
Author(s):  
Stephanos Dritsos ◽  
Dimitrios Baros
Keyword(s):  
Reinforced Concrete ◽  
Structural Elements ◽  
Flexural Stress ◽  
Reinforced Concrete Building ◽  
Reinforced Polymer ◽  
Concrete Building ◽  
Externally Bonded ◽  
Fibre Reinforced Polymer ◽  
Polymer Laminates ◽  
Design And Application

<p>The design and application of strengthening measures aiming to effectively counter possible weaknesses related to the extensive architectural modification of a characteristic reinforced concrete building is discussed in this chapter. Several balconies were removed as part of the architectural interventions. Externally bonded reinforcement consisting of steel and fibre reinforced polymer laminates was applied as an “answer” to possible changes in flexural stress of selected structural elements in the immediate area of the demolitions. A unique anchorage system was also designed and applied as an answer to the loss of development length of the main reinforcement bars of selected beams due to the removal of their cantilever parts.</p>

Experimental investigation of seismic strengthening of reinforced concrete short columns using externally bonded reinforcement, near surface mounted, and hybrid techniques

2019 ◽  
Vol 54 (9) ◽  
pp. 1177-1195 ◽  
Author(s):  
A Kargaran ◽  
A Kheyroddin
Keyword(s):  
Reinforced Concrete ◽  
Fiber Reinforced Polymer ◽  
Dissipated Energy ◽  
Fiber Reinforced ◽  
Near Surface ◽  
Short Columns ◽  
Reinforced Polymer ◽  
Shear Rupture ◽  
Externally Bonded ◽  
Near Surface Mounted

Nowadays, the existence of short columns is a major factor in the failure and collapse of structures during the earthquake. In this article, 10 reinforced concrete short columns are prepared and experimentally investigated under cyclic lateral displacements. Since failure in short columns under earthquake was in the form of diagonal cracks and shear rupture, two new techniques are proposed to strengthen short columns against seismic loads. These techniques include externally bonded reinforcement with carbon fiber-reinforced polymer sheets and near surface mounted with glass fiber-reinforced polymer bars in the form of transverse, diagonal, and hybrid strengthening techniques. The experimental results demonstrated that the above-mentioned strengthening techniques in short columns lead to a change in the type of failure from shear to flexural, and the change of crack patterns and columns failure. The mentioned strengthening methods lead to an increase of ductility, increase of load carrying capacity and increase of dissipated energy.

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