Analytical model to predict the lifetime of concrete members externally reinforced with FRP

Foraboschi, Paolo

doi:10.1016/j.tafmec.2014.12.002

Cited by 61 publications

(26 citation statements)

References 55 publications

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“…To describe the debonding as a Mode-II problem, a cohesive material law (CML) is introduced that represents the relationship between the interfacial shear stress (τ) and the relative displacement or slip (s) between the faces of the crack at any location along the interface. A similar approach is used for the FRP-concrete [39,40] or FRP-masonry [41][42][43][44] interface. The key assumption behind the use of a CML is the fact that the interface is fictitiously reduced to a zero-thickness layer of material whose properties are defined by the CML itself.…”

Section: Introductionmentioning

confidence: 99%

An indirect method to calibrate the interfacial cohesive material law for FRCM-concrete joints

et al. 2017

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The cohesive material law (CML), i.e., relationship between the interfacial shear stress and slip between a fiber reinforced composite and the substrate, is a fundamental tool to model the structural behavior of compositestrengthened elements. A crucial problem that researchers working in the field of strengthening applications with fiber reinforced cementitious matrix (FRCM) composites face is how to obtain the CML. A direct method to determine the CML could be applied if the longitudinal strain is measured along the bonded length. However, since the critical interface for some FRCM composites appears to be the interface between the fibers and matrix, measuring the fiber strain in FRCM composites is a difficult task due to the presence of the matrix that embeds the fiber textile. To overcome this difficulty, an indirect method is proposed in this paper. The parameters of the CML are determined by fitting experimental data in terms of peak load measured for different composite bonded lengths. The procedure is applied to single-lap shear test results previously published by the authors. The CML obtained shows good correlation with the CML obtained from direct calibration of strain profiles measured along the bonded length and is able to predict the experimental load responses.

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Section: Introductionmentioning

confidence: 99%

An indirect method to calibrate the interfacial cohesive material law for FRCM-concrete joints

et al. 2017

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“…Long-term durability of FRP strengthening work is a great concern of modern-day researches. One new finding that affects both masonry and concrete members that are externally strengthened using FRP, is delayed debonding, which is a phenomenological development of critical crack throughout the life-time of the structure along the substrate-FRP interface that causes the external FRP to lose bond stress and eventually reduce the lifetime of strengthening works (Foraboschi 2015). Shrestha et al (2014) pointed out that there is considerable influence of moisture in deteriorating the bond property and reduce the durability of FRP retrofitted works.…”

Section: Introductionmentioning

confidence: 99%

In-Plane Shear Performance of Masonry Walls after Strengthening by Two Different FRPs

Rahman

Ueda

2016

J. Compos. Constr.

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The present experimental study was aimed to investigate the in-plane shear performance of externally strengthened masonry walls using two types of fiber reinforced polymer (FRP) sheets− CFRP (Carbon fiber reinforced polymer) and PET-FRP (Polyethylene Terephthalate) sheets. Among these two, PET-FRP has a low tensile strength but possess a higher fracturing strain than CFRP. Twelve masonry walls made from clay brick were tested for static lateral loading under constant compression, after bonding CFRP and PET-FRP sheets onto their surfaces in three different configurations. The ultimate shear strength and deformation at peak load were the two important observations. The mechanisms by which load was carried were observed, varying from the initial uncracked state, to the final, fully cracked state. The results demonstrate that a significant increase in the in-plane shear capacity of masonry can be achieved by bonding these two FRPs to the surface of the walls but ductility is compromised when CFRP is used. Walls retrofitting with PET-FRP in a cross-diagonal fashion show a good ductile behavior in both pre-peak and post-peak regimes. The experimental data were used to assess the effectiveness of the strengthening of one FRP over the other. PET-FRP in diagonal configuration was found to be the most effective way of strengthening without compromising the two most essential aspects of masonry i.e strength and ductility.

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“…In addition, Foraboschi [31] presented an investigation on the prediction of the lifetime of concrete members with EBR, focusing on crack growths in the concrete cover due to the shear stresses, which are introduced by the EBR. An analytical method was derived and compared to experimental results.…”

Section: Long-term Behaviourmentioning

confidence: 99%

EBR Strengthening Technique for Concrete, Long-Term Behaviour and Historical Survey

Czaderski

Meier

2018

Polymers

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Epoxy bonded steel plates (externally bonded reinforcemen: EBR) for the strengthening of concrete structures were introduced to the construction industry in the late 1960s, and the use of fibre reinforced polymers (FRPs) was introduced in the 1990s, which means that these techniques have already been used in construction for 50 and 25 years, respectively. In the first part of the paper, a historical survey of the development and introduction of these strengthening techniques into the construction industry are presented. The monitoring of such applications in construction is very important and gives more confidence to this strengthening technique. Therefore, in the second part of the paper, two long-term monitoring campaigns over an extraordinarily long duration will be presented. Firstly, a 47-year monitoring campaign on a concrete beam with an epoxy bonded steel plate and, secondly, a 20-year monitoring campaign on a road bridge with epoxy bonded CFRP (carbon fibre reinforced polymers) strips are described. The paper is an expanded version of the paper presented at the SMAR2017 Conference.Keywords: externally bonded reinforcement; EBR; strengthening of reinforced concrete; epoxy adhesive; bond; steel; CFRP; long-term behaviour Historical Survey of Development of EBR Technique Research on EBR SteelThe first ideas on strengthening of concrete with epoxy bonded steel plates were presented in the 1960s by L'Hermite et al. Figure 1 showing the principle idea of applying a steel plate to a concrete beam with an adhesive (tole d'acier: steel plate and colle: adhesive). The first applications on a highway bridge and in a building followed in 1966-1967 [3]. Bresson [2] presented in the year 1971 the derivation of the differential equation of bond behaviour of EBR and its elastic solution. Afterwards, other researchers worked on that topic-for example, Johnson et al. [4] presented in 1981 a research study on sixteen tests on plated reinforced concrete members subjected to bending, shear and axial tension, in order to study the influence of geometric parameters on the maximum tensile strain that can be developed in a mild steel plate before breakdown of the adhesive layer or failure of the concrete member. No failures occurred in the epoxy adhesive, and strains exceeding yield could be developed in the plates. Furthermore, Dussek [5] described results of tests on plate-reinforced beams, discussed a design method and presented strengthening projects where steel plates were applied on several bridges in UK. A timeline of the developments discussed is displayed in Figure 2.In the 1970s and 1980s, besides the investigations mentioned above, research on the performance and on a better understanding on the epoxy bonded steel plates was also performed at Empa in City,

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Analytical model to predict the lifetime of concrete members externally reinforced with FRP

Cited by 61 publications

References 55 publications

An indirect method to calibrate the interfacial cohesive material law for FRCM-concrete joints

An indirect method to calibrate the interfacial cohesive material law for FRCM-concrete joints

In-Plane Shear Performance of Masonry Walls after Strengthening by Two Different FRPs

EBR Strengthening Technique for Concrete, Long-Term Behaviour and Historical Survey

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