Pull-out behaviour of near surface mounted steel wire rope bonded to clay-brick masonry

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.

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Experimental and Numerical Study of Behaviour of Reinforced Masonry Walls with NSM CFRP Strips Subjected to Combined Loads

Buildings ◽

10.3390/buildings10060103 ◽

2020 ◽

Vol 10 (6) ◽

pp. 103

Author(s):

Houria Hernoune ◽

Benchaa Benabed ◽

Antonios Kanellopoulos ◽

Alaa Hussein Al-Zuhairi ◽

Abdelhamid Guettala

Keyword(s):

Failure Modes ◽

Numerical Study ◽

Masonry Wall ◽

Brick Masonry ◽

Masonry Walls ◽

Near Surface ◽

Combined Loads ◽

Reinforced Masonry ◽

Brick And Mortar ◽

Near Surface Mounted

Near surface mounted (NSM) carbon fibers reinforced polymer (CFRP) reinforcement is one of the techniques for reinforcing masonry structures and is considered to provide significant advantages. This paper is composed of two parts. The first part presents the experimental study of brick masonry walls reinforced with NSM CFRP strips under combined shear-compression loads. Masonry walls have been tested under vertical compression, with different bed joint orientations 90° and 45° relative to the loading direction. Different reinforcement orientations were used including vertical, horizontal, and a combination of both sides of the wall. The second part of this paper comprises a numerical analysis of unreinforced brick masonry (URM) walls using the detailed micro-modelling approach (DMM) by means of ABAQUS software. In this analysis, the non-linearity behavior of brick and mortar was simulated using the concrete damaged plasticity (CDP) constitutive laws. The results proved that the application of the NSM-CFRP strips on the masonry wall influences significantly strength, ductility, and post-peak behavior, as well as changing the failure modes. The adopted DMM model provides a good interface to predict the post peak behavior and failure mode of unreinforced brick masonry walls.

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Characterization and Simulation of the Bond Response of NSM FRP Reinforcement in Concrete

Materials ◽

10.3390/ma13071770 ◽

2020 ◽

Vol 13 (7) ◽

pp. 1770 ◽

Cited By ~ 3

Author(s):

Javier Gómez ◽

Lluís Torres ◽

Cristina Barris

Keyword(s):

Load Capacity ◽

Numerical Procedure ◽

Fiber Reinforced Polymer ◽

Near Surface ◽

Bond Slip ◽

Pull Out ◽

Reinforced Polymer ◽

Frp Reinforcement ◽

Near Surface Mounted ◽

Shear Stress And Strain

The near-surface mounted (NSM) technique with fiber reinforced polymer (FRP) reinforcement as strengthening system for concrete structures has been broadly studied during the last years. The efficiency of the NSM FRP-to-concrete joint highly depends on the bond between both materials, which is characterized by a local bond–slip law. This paper studies the effect of the shape of the local bond–slip law and its parameters on the global response of the NSM FRP joint in terms of load capacity, effective bond length, slip, shear stress, and strain distribution along the bonded length, which are essential parameters on the strengthening design. A numerical procedure based on the finite difference method to solve the governing equations of the FRP-to-concrete joint is developed. Pull-out single shear specimens are tested in order to experimentally validate the numerical results. Finally, a parametric study is performed. The effect of the bond–shear strength slip at the bond strength, maximum slip, and friction branch on the parameters previously described is presented and discussed.

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

Engineering Computations ◽

10.1108/ec-01-2019-0032 ◽

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.

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