Retrofitting of Distressed RC Structures Using Near Surface Mounted Reinforcement

2021 ◽  
pp. 205-216
Author(s):  
Y. K. Guruprasad ◽  
Aditya Poudel ◽  
Y. V. Gautam Sandesh ◽  
Hage Rabin ◽  
Acintya Upmanyu
Keyword(s):  
Near Surface ◽  
Rc Structures ◽  
Near Surface Mounted

Numerical simulation of the debonding process in pull-out tests of near-surface mounted FRP rod in concrete

2019 ◽  
Vol 37 (3) ◽  
pp. 1109-1130
Author(s):  
Tie-Lin Chen ◽  
Wenbin Tao ◽  
Wenjun Zhu ◽  
Mozhen Zhou
Keyword(s):  
Three Dimensional ◽  
Crack Model ◽  
Bond Failure ◽  
Near Surface ◽  
Content Type ◽  
Rc Structures ◽  
Pull Out ◽  
Smeared Crack ◽  
Near Surface Mounted ◽  
Debonding Process

Purpose Near-surface mounted (NSM) fiber-reinforced polymer (FRP) rod is extensively applied in reinforced concrete (RC) structures. The mechanical performances of NSM FRP-strengthened RC structures depend on the bond behavior between NSM reinforcement and concrete. This behavior is typically studied by performing pull-out tests; however, the failure behavior, which is crucial to the local debonding process, is not yet sufficiently understood. Design/methodology/approach In this study, a three-dimensional meso-scale finite element method considering the cohesion and adhesion failures is presented to model the debonding failure process in pull-out tests of NSM FRP rod in concrete. The smeared crack model is used to capture the cohesion failures in the adhesive or concrete. The interfacial constitutive model is applied to simulate the adhesion failures on the FRP-adhesive and concrete-adhesive contact interfaces. Findings The present method is first validated by two simple examples and then applied to a practical NSM FRP system. This work studied in detail the debonding process, the bond failure types, the location of peak bond stress, the transmitting deformation in adhesive and the morphology of contact zone. The developed method provides a practical and convenient tool applicable for further investigations on the debonding mechanism for the NSM FRP rod in concrete. Originality/value A three-dimensional meso-scale finite element method considering the cohesion and adhesion failures is presented to model the debonding failure in NSM FRP-strengthened RC structures. The smeared crack model and the interfacial constitutive model are introduced to develop a convenient approach to analyze the failures in adhesive, concrete and related interfaces. The developed numerical method is applicable for studying the debonding process, the bond failure types, the location of peak bond stress, the transmitting deformation in adhesive and the morphology of contact zone in detail.

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

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.

Flexural Behavior of near Surface Mounted CFRP Bars Strengthened Reinforced Concrete Beams

2012 ◽  
Vol 535-537 ◽  
pp. 1702-1710 ◽  
Author(s):  
Shuaib H. Ahmad ◽  
Abdullah Bin Najm ◽  
Antonio Naani
Keyword(s):  
Reinforced Concrete ◽  
Analytical Model ◽  
Concrete Beams ◽  
Reinforced Concrete Beams ◽  
Flexural Behavior ◽  
Rc Beams ◽  
Near Surface ◽  
Rc Structures ◽  
Cfrp Laminates ◽  
Near Surface Mounted

In recent decades, use of fibre reinforced polymers (FRP) materials has become very popular for strengthening / re-strengthening of reinforced concrete (RC) structures. This includes flexural and shear strengthening of RC structural members such as slabs, beams and columns.In this study, a computerized analytical model is presented to predict the load-deflection response of flexure critical RC beams externally strengthened with near surface mounted (NSM) CFRP laminates. The analyical model utilizes constitutive material properties of concrete, reinforcing steel, CFRP laminate materials, strain compatibility, sectional analysis to develop moment-curvature relationships, which then are used to generate the load-rotations and load-deflection of the flexure critical RC Beams strengthend with NSM CFRP laminates. For validation of the analytical model, the predictions of the analytical model are compared with the experimental results of flexure critical RC beams strengthened with NSM CFRP laminates and the comparisons are judged to be good.As a part of the experimental investigation of this study, a series of 18 full scale beams Reinforced Concrete Beams strengthened with carbon fiber reinforced polymer (CFRP) laminates will be tested in flexure and shear. The results of flexural tests will be analyzed and compared with the predictions of the analytical model.

scholarly journals Bond Behaviour of Near-Surface Mounted Strips in RC Beams—Experimental Investigation and Numerical Simulations

Materials ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 4362
Author(s):  
Renata Kotynia ◽  
Hussien Abdel Baky ◽  
Kenneth W. Neale
Keyword(s):  
Concrete Strength ◽  
Element Model ◽  
Steel Reinforcement ◽  
Reinforcement Ratio ◽  
Experimental Program ◽  
Fe Model ◽  
Bond Behaviour ◽  
Near Surface ◽  
Cfrp Laminates ◽  
Near Surface Mounted

This paper presents an investigation of the bond mechanism between carbon fibre reinforced polymer (CFRP) laminates, concrete and steel in the near-surface mounted (NSM) CFRP-strengthened reinforced concrete (RC) beam-bond tests. The experimental program consisting of thirty modified concrete beams flexurally strengthened with NSM CFRP strips was published in. The effects of five parameters and their interactions on the ultimate load carrying capacities and the associated bond mechanisms of the beams are investigated in this paper with consideration of the following investigated parameters: beam span, beam depth, longitudinal tensile steel reinforcement ratio, the bond length of the CFRP strips and compressive concrete strength. The longitudinal steel reinforcement was cut at the beam mid-span in four beams to investigate a better assessment of the influence of the steel reinforcement ratio on the bond behaviour of CFRP to concrete bond behaviour. The numerical analysis implemented in this paper is based on a nonlinear micromechanical finite element model (FEM) that was used for investigation of the flexural behaviour of NSM CFRP-strengthened members. The 3D model based on advanced CFRP to concrete bond responses was introduced to modelling of tested specimens. The FEM procedure presents the orthotropic behaviour of the CFRP strips and the bond response between the CFRP and concrete. Comparison of the experimental and numerical results revealed an excellent agreement that confirms the suitability of the proposed FE model.

scholarly journals Activated Ductile CFRP NSMR Strengthening

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2821
Author(s):  
Jacob Wittrup Schmidt ◽  
Christian Overgaard Christensen ◽  
Per Goltermann ◽  
José Sena-Cruz
Keyword(s):  
Failure Modes ◽  
Elastic Response ◽  
Applied Theory ◽  
Strengthening Effect ◽  
The Novel ◽  
Near Surface ◽  
Linear Elastic ◽  
Near Surface Mounted ◽  
High Elongation ◽  
Strengthened Beam

Significant strengthening of concrete structures can be obtained when using adhesively-bonded carbon fiber-reinforced polymer (CFRP) systems. Challenges related to such strengthening methods are; however, the brittle concrete delamination failure, reduced warning, and the consequent inefficient use of the CFRP. A novel ductile near-surface mounted reinforcement (NSMR) CFRP strengthening system with a high CFRP utilization is introduced in this paper. It is hypothesized that the tailored ductile enclosure wedge (EW) end anchors, in combination with low E-modulus and high elongation adhesive, can provide significant strengthening and ductility control. Five concrete T-beams were strengthened using the novel system with a CFRP rod activation stress of approximately 980 MPa. The beam responses were compared to identical epoxy-bonded NSMR strengthened and un-strengthened beams. The linear elastic response was identical to the epoxy-bonded NSMR strengthened beam. In addition, the average deflection and yielding regimes were improved by 220% and 300% (average values), respectively, with an ultimate capacity comparable to the epoxy-bonded NSMR strengthened beam. Reproducible and predictable strengthening effect seems obtainable, where a good correlation between the results and applied theory was reached. The brittle failure modes were prevented, where concrete compression failure and frontal overload anchor failure were experienced when failure was initiated.

scholarly journals Near-Surface Mounted Reinforcement of Sawn Timber Beams-FEM Approach

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2780
Author(s):  
Izabela Burawska-Kupniewska ◽  
Piotr Beer
Keyword(s):  
European Standard ◽  
Near Surface ◽  
Bending Tests ◽  
Starting Point ◽  
Structural Applications ◽  
Bending Stresses ◽  
Complex Models ◽  
Near Surface Mounted ◽  
Sawn Timber ◽  
Timber Beams

The demand for timber has increased significantly in recent years. Therefore, reliable tools are needed to predict the mechanical properties of sawn timber, especially for structural applications. Very complex models require a lot of input data for analysis, which cannot always be guaranteed, especially in industrial practice. Thus, a simplified model for material description was developed and assessed with experiments (static bending tests carried out in accordance with the guidelines suggested in the European standard EN 408) and an analytical approach (gamma method according to the guidelines given in the European standard EN 1995). The effective stiffness was calculated as a major parameter, which has an influence on the elements’ behavior. The model included a near-surface mounted (NSM) local reinforcement technique, with CFRP strips of Scots pine timber beams being subjected to bending stresses. It is anticipated that the developed model can be a starting point for the repair engineering field, contributing to decision-making regarding conservation technique selection and range. Next, improvements of the model will provide more and more realistic results for numerical analysis in terms of the obtained failure mechanisms for sawn timber elements.

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