Fatigue Strengthening of Metallic Structures with a Thermally Activated Shape Memory Alloy Fiber-Reinforced Polymer Patch

Zheng, Botong; Dawood, Mina

doi:10.1061/(asce)cc.1943-5614.0000776

Cited by 40 publications

(19 citation statements)

References 31 publications

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“…However, the SME property is mostly used in post-tensioning of the SMA reinforcement [18,24,25]. The material is pre-deformed at ambient temperature and attached to a parent steel structure.…”

Section: Smas In Civil Engineeringmentioning

confidence: 99%

Thermally activated iron-based shape memory alloy for strengthening metallic girders

Izadi

Hosseini

Michels

et al. 2019

Thin-Walled Structures

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The study presents a new retrofit solution for strengthening metallic I-girders. The retrofit system involves two iron-based shape memory alloy (Fe-SMA, 'memory-steel') strips (each with a width and thickness of 50 and 1.5 mm, respectively) that are mechanically anchored (using friction clamps) to the girders. The shape memory effect (SME) of the Fe-SMA material has been used to activate/prestress the strips by heating to a predefined temperature. The main advantage of the proposed SMA-retrofit system is that, unlike conventional systems, it can prestress itself without a need for heavy hydraulic jacks, which then results in a significant reduction of the required time, labor works and cost of prestressing process. In order to evaluate the efficiency of the proposed retrofit system, in this study, a series of static and fatigue four-point bending tests were performed on a 6.4-m SMA-retrofitted beam. Five static

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Section: Smas In Civil Engineeringmentioning

confidence: 99%

Thermally activated iron-based shape memory alloy for strengthening metallic girders

Izadi

Hosseini

Michels

et al. 2019

Thin-Walled Structures

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“…This patching system generates compressive stresses in the steel after the activation of SMA wires. Through a comprehensive experimental investigation, Zheng and Dawood [39] proved that strengthening with the help of a prestressed SMA/CFRP patching system can lead to upgrading the fatigue detail from worse than an American Association of State Highway and Transportation Officials (AASHTO) Category E detail to better than a Category B detail. However, near-crack debonding was reported in all of the specimens strengthened with CFRP and SMA/CFRP patches during the fatigue loading, which has a negative impact on the fatigue life improvement, but is unavoidable in adhesively-bonded reinforcements [39].…”

Section: Introductionmentioning

confidence: 99%

Mode I fatigue crack arrest in tensile steel members using prestressed CFRP plates

Hosseini

Ghafoori

Motavalli

et al. 2017

Composite Structures

113

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Numerous studies in the literature have shown that the strengthening of steel members using carbon fiber reinforced polymer (CFRP) composites can significantly extend the fatigue life of these structures. However, not enough attention has been focused on the potential of prestressed CFRP reinforcements for fatigue crack arrest in such members. In the current study, a simple analytical model is proposed to calculate the required prestressing level in the CFRP reinforcements in order to arrest the propagation of an existing fatigue crack in tensile steel members. Furthermore, a novel mechanical unbonded system is developed to anchor the high prestressing forces in CFRP reinforcements to the steel substrate using friction. A set of fatigue tests are performed on unstrengthened and strengthened precracked steel plates to verify the proposed model. The experimental results of the current study showed that the application of nonprestressed ultra-high modulus CFRP plates as externally bonded reinforcements can increase the fatigue life of precracked steel plates by a factor of 4.3. However, fatigue crack arrest is only possible when prestressed CFRPs of a certain prestressing level are used. Based on the analytical, numerical, and experimental results of the current study, it can be concluded that existing fatigue cracks in tensile steel members can be arrested using the proposed prestressed unbonded reinforcement system with the initial prestressing level calculated using the proposed model. In addition, some design recommendations are provided for fatigue crack arrest in practical cases.

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“…For cracked metallic structures, other fatigue crack repair methods, including the hole drilling, weld repair, use of doublers or splice plates, and posttensioning, have been used (Dexter and Ocel 2013). The adhesive-bonded FRP patches can significantly increase the fatigue life by reducing the crack tip stress intensity factor (SIF) (Liu et al 2009a;Täljsten et al 2009;Hmidan et al 2014Hmidan et al , 2015Wang et al 2016b;Zheng and Dawood 2017;Aljabar et al 2017). A reduction in the SIF can be predicted by several calculation methods.…”

Section: Introductionmentioning

confidence: 99%

Optimization of Fiber-Reinforced Polymer Patches for Repairing Fatigue Cracks in Steel Plates Using a Genetic Algorithm

Lenwari

2020

J. Compos. Constr.

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A practical design optimization of fiber-reinforced polymer (FRP) patches for repairing fatigue cracks in metallic structures is presented. The design procedure combines finite-element (FE), genetic programming (GP), and genetic algorithm (GA) approaches. An optimum patch design is defined as the combination of design parameters that simultaneously minimizes the patch volume and reduces the stress intensity factor (SIF) range below the fatigue threshold range. A patching correction factor, which accounts for the positive effects of material and geometric properties of the patch and adhesive layer on the SIF solution, is proposed. The correction factor is developed by performing symbolic regression via GP analyses on the SIF values obtained from the three-dimensional FE models. The closed-form SIF solution facilitates the visualization of the effects of design parameters, simplifies the calculation of fatigue life, and reduces the computation effort for design optimization. An example of the center-cracked steel plate subjected to constant amplitude fatigue loading and then repaired with double-sided adhesive-bonded FRP patches is used to illustrate the optimization procedure.

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Fatigue Strengthening of Metallic Structures with a Thermally Activated Shape Memory Alloy Fiber-Reinforced Polymer Patch

Cited by 40 publications

References 31 publications

Thermally activated iron-based shape memory alloy for strengthening metallic girders

Thermally activated iron-based shape memory alloy for strengthening metallic girders

Mode I fatigue crack arrest in tensile steel members using prestressed CFRP plates

Optimization of Fiber-Reinforced Polymer Patches for Repairing Fatigue Cracks in Steel Plates Using a Genetic Algorithm

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