Inverse Calculation of Timber-CFRP Composite Beams Using Finite Element Analysis

Saad, Khaled; Lengyel, András

doi:10.3311/ppci.16527

Cited by 3 publications

(3 citation statements)

References 32 publications

(39 reference statements)

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“…In contrast, it was also demonstrated that, in most situations, the addition of reinforcements had a slight effect on stiffness [134,[150][151][152][153][154], and the increase does not usually exceed 30%; it is primarily negligible and occasionally much more significant. Bidirectional carbon fabrics and laminate strips were applied for strengthening timber beams taken from an old bridge.…”

Section: Effect Of the Cfrp On Flexural Stiffness Enhancement Of Timbermentioning

confidence: 96%

Strengthening Timber Structural Members with CFRP and GFRP: A State-of-the-Art Review

Saad

Lengyel

2022

Polymers

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The application of fibre-reinforced polymers (FRP) for strengthening timber structures has proven its efficiency in enhancing load-bearing capacity and, in some cases, the stiffness of structural elements, thus providing cost-effective and competitive alternatives both in new design and retrofitting existing historical buildings. Over the last few decades, several reinforcing materials and techniques evolved, and considerable progress was made in numerical modelling, especially using the finite element method. As this field of research has become extensive and diversified, as well as numerous contradicting results have emerged, a thorough review is necessary. This manuscript covers the topics of historical preliminaries, reinforcing with carbon and glass fibre composites, bond characteristics, main reinforcing techniques, modelling of knots, and the effects of the fibre waviness on the composite behaviour. A detailed overview is given on the experimental and numerical investigation of mechanics of strengthened beams. A one-of-a-kind table that compares the stiffness improvement observed in several studies with analytical estimates. Attention is drawn to a number of challenges that have arisen, e.g., the moderate stiffness enhancement, composite-to-wood interface, modelling of knots, and strengthening of defected timber members. This paper can be used as a starting point for future research and engineering projects.

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Section: Effect Of the Cfrp On Flexural Stiffness Enhancement Of Timbermentioning

confidence: 96%

Strengthening Timber Structural Members with CFRP and GFRP: A State-of-the-Art Review

Saad

Lengyel

2022

Polymers

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“…Based on comparison with experimental results, they conclude that in modelling of the triaxial anisotropic materials, the Hill criterion is insufficiently accurate, and that the novel QMS model is the most accurate. 2D and 3D modelling of timber beams was applied by Saad and Lengyel [7]. Their research is based on the analysis of an elastic and plastic orthotropic material (biaxial anisotropic), and the conclusion is that Hill's criterion can be applied for modelling of those materials.…”

Section: Introductionmentioning

confidence: 99%

Experimental Research and FE Model of a Bolted Steel-CLT Composite Connection

Milić

Vacev

Petronijević

et al. 2023

Period. Polytech. Civil Eng.

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Steel-timber composite structures have numerous advantages compared to steel only and timber only structures. One of the most important parts of a composite structure is the composite connection. Object of this research was a steel-CLT composite connection consisting of a steel profile, a cross-laminated timber (CLT) panel and a bolt with nut and washer. Aim of the research was to develop an efficient finite element (FE) model of a bolted steel-CLT composite connection and to validate it experimentally. The research process consisted of several steps: experimental testing of the considered connection using asymmetrical push-out test, numerical modelling and analysis of the connection using Finite Element Method (FEM), validation of the numerical model using experimental results, and parametric study of the proposed numerical model. For numerical analysis, an innovative method for timber modelling has been proposed. The comparison between the experimental and numerical research results demonstrated that the proposed numerical model was convenient for practical application in structure analyses. The parametric study showed that, in some cases, atypical failure modes of the connection occurred. Based on registered behavior, a recommendation is given to calculate the load capacity of the connection integrally, taking into account both the primary (Johansen’s) and the secondary (rope effect) part of the connection strength, instead partially, as proposed by EN standards.

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“…It was also shown that, in most cases, strengthening timber elements with CFRP had only a minor influence on stiffness [ 14 , 15 , 16 ], and the increase is generally not more than 30%. Wood beams from an ancient bridge were strengthened using bidirectional carbon fabrics and laminate strips, resulting in a substantial improvement in shear and bending capacity (40–53%) but only a modest increase in stiffness (17–27%) [ 17 ].…”

Section: Introductionmentioning

confidence: 99%

Experimental, Analytical, and Numerical Assessments for the Controversial Elastic Stiffness Enhancement of CFRP-Strengthened Timber Beams

Saad

Lengyel

2022

Polymers

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The strengthening of timber beams with carbon-fibre-reinforced polymers (CFRP) has been widely used in the last decades to enhance the behaviour of historical or new timber structures, usually for bending. While considerable improvement in capacity and ductility is typically achieved, the increase in stiffness was, in many cases, well short of analytical expectations, which tend to overestimate stiffness. This study addresses the problem by investigating the underlying mechanical behaviour using experimental, analytical, and numerical tools on a sample of Norway spruce (Picea abies) beams reinforced with carbon-fibre fabric. In the experimental program, each beam is tested for bending with and without CFRP reinforcement in order to determine specimen-specific stiffness increase on an individual basis. The reinforcement yielded an increase of 27% in capacity, 53% in ultimate displacement, and 133% in compliance, verifying its efficiency. Axial compression tests on an independent sample are also performed to verify modulus of elasticity in compression. Numerical computations based on a beam model and a three-dimensional finite element model are performed with the introduction of separate moduli of elasticity for tension and compression in timber. Inverse computation using the experimental load–deflection curves yielded the moduli and the compression yield stress of timber to provide the best match between tests and simulations. The mean difference of only 6% in stiffness between FEM and the tests is obtained. The dominance of normal stresses in the longitudinal direction is found, in correspondence with the experimentally observed tensile failure of timber (apart from a few defected specimens). Compression yield stresses are within 7% (beam model) and 2% (FEM) error compared with the control axial tests. The differences between FE simulations and tests in ultimate load and compliance are within 1%. This study concludes that the application of CFRP in the composite beams enables the determination of timber material properties opposed to pure timber beams without reinforcement, and the adoption of separate moduli of elasticity for tension and compression leads to adequate modelling of reinforced timber beams.

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Inverse Calculation of Timber-CFRP Composite Beams Using Finite Element Analysis

Cited by 3 publications

References 32 publications

Strengthening Timber Structural Members with CFRP and GFRP: A State-of-the-Art Review

Strengthening Timber Structural Members with CFRP and GFRP: A State-of-the-Art Review

Experimental Research and FE Model of a Bolted Steel-CLT Composite Connection

Experimental, Analytical, and Numerical Assessments for the Controversial Elastic Stiffness Enhancement of CFRP-Strengthened Timber Beams

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