Strengthening of old metallic structures in fatigue with prestressed and non-prestressed CFRP laminates

Täljsten, Björn; Hansen, Christian; Schmidt, Jacob Wittrup

doi:10.1016/j.conbuildmat.2008.08.001

Cited by 166 publications

(80 citation statements)

References 5 publications

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“…In several studies, the fatigue behavior of notched steel members reinforced by using prestressed CFRP laminates is considered. Prestressed reinforcements were observed to be more effective in extending the crack growth life [11,17,18]. Crack patching by prestressed CFRP strips produces, in fact, supplementary benefits since the compressive stresses introduced by prestressing the steel elements give rise to an additional reduction of the COD and emphasize the crack closure phenomenon.…”

Section: Previous Studiesmentioning

confidence: 99%

Fatigue crack growth in CFRP-strengthened steel plates

Colombi

Fava

Sonzogni

2015

Composites Part B: Engineering

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a b s t r a c tIn this paper fatigue crack growth in steel plates reinforced by using carbon fiber reinforced (CFRP) strips is investigated from the experimental, numerical and analytical point of view. Single edge notched tension (SENT) specimens were strengthened with different reinforcement configurations and tested at a stress ratio R of 0.4. Different initial damage levels were considered and the experimental results showed that the reinforcement application can effectively reduce the crack growth rate and significantly extend the fatigue life. Numerical models (finite elements) were also developed to evaluate the stress intensity factor (SIF) and the crack opening displacement (COD) profile. Based on the numerical results, an analytical model was proposed to predict the fatigue crack growth rate and the fatigue crack growth curves. The analytical results are validated by comparing the fatigue crack growth curves to the experimental ones.

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Section: Previous Studiesmentioning

confidence: 99%

Fatigue crack growth in CFRP-strengthened steel plates

Colombi

Fava

Sonzogni

2015

Composites Part B: Engineering

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“…However, although the morphological characteristics of FRP have close correlation with its mechanical properties, they have not been deeply studied using scanning electron microscopy (SEM) technique. Nowadays, in order to understand failure sequences of FRP composites and epoxy adhesives it has been correlated to the mechanical behavior of composites materials when they are used in retrofitting any concrete or steel element [1][2][3][4][5][6][7] . In addition, majority of researches that have focused on FRP composites and epoxy adhesive mechanical behavior did not explore the morphology of materials.…”

Section: Introductionmentioning

confidence: 99%

Carbon Fiber Reinforced Polymer and Epoxy Adhesive Tensile Test Failure Analysis Using Scanning Electron Microscopy

2017

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Morphological characteristics analysis before and after tensile tests were studied using scanning electron microscopy (SEM) technique to follow the failure evolution on carbon fiber reinforced polymer (CFRP) and epoxy resins. Micrograph analysis of CFRP plate before tensile test shows some intrinsic manufacturing defects, which can influence the mechanical properties of the material. Micrograph analysis after tensile test shows that cracks propagation start in manufacturing defects, which lead the carbon fiber to be pulled out instead of breaking. Thus, cracks propagate through interfacial zones affecting the sharing force between matrix and carbon fiber. For the epoxies materials, the microscopy analysis showed that although epoxies adhesive have different phase distribution before tensile test, failure surfaces are described by fine granular particles covalent bonded with matrix, and the material fails in a brittle manner when the strength outstripped these bonds. Failure process for each material correlating the mechanical properties with the morphological characteristics of materials was discussed.

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“…Bassetti et al [16,17] conducted both small-scale tests and full-scale tests on old riveted girders reinforced with prestressed CFRP laminates and showed that depending on the ratio of the applied load, the reinforcement ratio, and the prestressing level, the use of CFRP laminates can lead to an increase in fatigue life of more than 16 times. Experiments by Täljsten et al [18] showed that it is feasible to increase the fatigue life almost four times compared to a reference specimen reinforced with non-prestressed laminates. When prestressing the laminates the crack growth was completely stopped even though the prestressing level was rather low.…”

Section: Introductionmentioning

confidence: 99%

“…The increase of the fatigue resistance of steel structures by externally bonding non-prestressed CFRP laminates has been less studied [8][9][10][11] and the fatigue life increases reported are limited to a factor of 3.4 for normal modulus CFRP laminates (E 11 < 200 GPa). Little research has been reported on the use of prestressed CFRP laminates for strengthening steel structures [16][17][18][19]. Bassetti et al [16,17] conducted both small-scale tests and full-scale tests on old riveted girders reinforced with prestressed CFRP laminates and showed that depending on the ratio of the applied load, the reinforcement ratio, and the prestressing level, the use of CFRP laminates can lead to an increase in fatigue life of more than 16 times.…”

Section: Introductionmentioning

confidence: 99%

CFRP-Strengthening and Long-Term Performance of Fatigue Critical Welds of a Steel Box Girder

et al. 2014

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Empa's research efforts in the 1990s provided evidence that a considerable increase of the fatigue strength of welded aluminum beams can be achieved by externally bonding pultruded carbon fiber reinforced polymer (CFRP) laminates using rubber-toughened epoxies over the fatigue-weak welding zone on their tensile flange. The reinforcing effect obtained is determined by the stiffness of the unidirectional CFRP laminate which has twice the elastic modulus of aluminum. One can therefore easily follow that an unstressed CFRP laminate reinforcement of welded beams made of steel will not lead to a substantial increase in fatigue strength of the steel structure. This consideration led to the idea of prestressing an external reinforcement of the welded zone. The present investigation describes experimental studies to identify the adhesive system suitable for achieving high creep and fatigue strength of the prestressed CFRP patch. Experimental results (Wöhler-fields) of shear-lap-specimens and welded steel beams reinforced with prestressed CFRP laminates are presented. The paper concludes by presenting a field application, the reinforcement of a steel pendulum by adhesively bonded prestressed CFRP laminates to the tensile flanges of the welded box girder. Inspections carried out periodically on this structure revealed neither prestress losses nor crack initiation after nine years of service.

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Strengthening of old metallic structures in fatigue with prestressed and non-prestressed CFRP laminates

Cited by 166 publications

References 5 publications

Fatigue crack growth in CFRP-strengthened steel plates

Fatigue crack growth in CFRP-strengthened steel plates

Carbon Fiber Reinforced Polymer and Epoxy Adhesive Tensile Test Failure Analysis Using Scanning Electron Microscopy

CFRP-Strengthening and Long-Term Performance of Fatigue Critical Welds of a Steel Box Girder

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