Fracture mechanics in timber engineering – Strength analyses of components and joints

Serrano, Erik; Gustafsson, Peter

doi:10.1617/s11527-006-9121-0

Cited by 78 publications

(34 citation statements)

References 5 publications

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“…In this case, the curvature (marked over top four layers in stiffness profile plot) is computed from the 4 topmost lamellas where f c,L = −52.0N∕mm 2 and f t,L (x) is obtained from the strength profile of the corresponding lamella. The coefficients which are constant within the beam are (Dorn 2012) In accordance with the findings presented in Serrano and Gustafsson (2007), a mean stress approach is pursued. Consequently, the stress components 11 , 22 , and 12 are not compared directly within each integration point.…”

Section: Models For the Bending Strengthmentioning

confidence: 99%

“…In accordance thereto, in Falk and Colling (1995) the lamination effect -describing the homogenisation of material fluctuations from individual timber boards to GLT structures-was investigated in detail and its ranges were calculated. Serrano and Gustafsson (2007) discussed different fracture mechanics-based approaches for assessing the strength of timber structures. The concepts are implemented into a probabilistic framework in the work of Danielsson and Gustafsson (2011), where a combination of Weibull weakestlink theory and mean stress method is proposed.…”

Section: Introductionmentioning

confidence: 99%

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Experimental study on glued laminated timber beams with well-known knot morphology

2018

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Nowadays, the impact of knots on the failure behaviour of glued laminated timber (GLT) beams is considered by subjecting the single lamellas to a strength grading process, where, i.a., tracheid effect-based laser scanning is used to obtain information about knot properties. This approach single-handedly defines the beam's final strength properties according to current standards. At the same time, advanced production processes of such beams would allow an easy tracking of a scanned board's location, but, at this point, previously obtained detailed information is already disregarded. Therefore, the scanning data is used to virtually reconstruct knot geometries and group them into sections within GLT beams. For this study, a sample of 50 GLT beams of five different configuration types was produced and tested under static four-point-bending until failure. As for each assembled lamella the orientation and position within the corresponding GLT beam is known, several parameters derived from the reconstructed knots can be correlated to effective GLT properties. Furthermore, the crack patterns of the tested beams are manually recorded and used to obtain measures of cracks. A detailed analysis of the generated data and their statistical evaluation show that, in the future, dedicated mechanical models for such timber elements must be developed to realistically predict their strength properties. A potential approach, using fluctuating section-wise effective material properties, is proposed.

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Section: Models For the Bending Strengthmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Experimental study on glued laminated timber beams with well-known knot morphology

2018

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“…The load carrying capacity of the conventional stiff adhesive bond line is highly dependent on the softening behaviour (Serrano and Gustafsson 2006), and was thus modelled with bilinear softening illustrated for pure shear in Fig. 3, as typical for structural adhesives (Wernersson 1990).…”

Section: Numerical Strength Analysismentioning

confidence: 99%

Use of a resilient bond line to increase strength of long adhesive lap joints

2017

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The load capacity of long adhesive lap joints is often governed by stress concentrations at the lap ends. This paper investigates a method to minimize these stress concentrations by using a bond line with low shear stiffness and sufficient strength, here denoted as a resilient bond line. The resilient bond line is intended to increase the load carrying capacity of long lap joints by achieving a more uniform shear stress distribution while maintaining an elastic joint behaviour without damage or plastic deformation. The study comprises analytical, numerical and full-sized experimental work on double lap joints with lengths 200-700 mm comparing conventional stiff bond lines to resilient bond lines. Different resilient bonds lines were obtained by using rubber-like adhesives and by having a rubber mat within the bond line. An analytical definition of a 'long' lap joint is suggested and a study of adhesive-rubber bonding is also presented. The numerical analysis clearly indicates that an increase in load carrying capacity is made possible using resilient bond lines. A good agreement is also found between the numerical results and the analytical Volkersen theory, indicating that reasonable strength predictions can be obtained by hand calculations if the joint is designed in order to minimize the influence of peel stress. The experimental results of the resilient bond line verify the numerical findings, although production difficulties decrease the statistical significance of the result. On the contrary, the experimental results of the conventional bond lines significantly exceeded the numerical predictions, showing similar load carrying capacities to the resilient bond line. This is probably due to the specific boundary conditions used in the test setup. Despite some contradictory experimental results, the conclusion of this study is that the efficiency of long lap joints can be increased by the use of a bond line with low shear stiffness and sufficient strength.

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“…The progressive cracking process can be perfectly described by the models. A fracture process zone is assumed ahead of the crack tip, which is considered as a fictitious crack with a constitutive relation to model the cracking behavior (Serrano and Gustafsson 2007). After reaching maximum stress level, the behavior of fracture zone will switch to a softening segment with increasing damage.…”

Section: Introductionmentioning

confidence: 99%

Experimental investigation on the ultimate strength of partially infilled and steel-braced reinforced concrete frames

Dubey¹,

Kute²

2013

Int J Adv Struct Eng

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This paper investigates the mechanical performance of longitudinally cracked glulam columns under eccentric compression loads. Experimental investigation was conducted to explore the influence of initial cracks on the failure modes and load bearing capacity of glulam columns. Two different crack patterns named DC and IC, and two column lengths (i.e. 600 and 1100 mm) were considered in the experiments. It was indicated that these two crack patterns reduced the capacity of slender glulam columns and the difference of failure modes was observed between glulam columns with and without initial cracks. Further, a numerical model was developed and validated by the test results. With the application of cohesive zone material model, the propagation of initial cracks could be considered in the numerical modeling. A parametric study was carried out by the verified model and the influence of crack lengths and crack locations was further investigated. From the numerical analysis, it was found that through cracks reduced the capacity of glulam columns significantly. Also, crack location impacts the capacity of glulam columns and the extent of impact relates to the slenderness ratio of the columns, while cracks with different lengths have similar influence on the capacity of columns.

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Fracture mechanics in timber engineering – Strength analyses of components and joints

Cited by 78 publications

References 5 publications

Experimental study on glued laminated timber beams with well-known knot morphology

Experimental study on glued laminated timber beams with well-known knot morphology

Use of a resilient bond line to increase strength of long adhesive lap joints

Experimental investigation on the ultimate strength of partially infilled and steel-braced reinforced concrete frames

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