Effect of fire exposure on the mechanical properties of glued laminated timber

Yang, Tsung Han; Wang, Song-Yung; Tsai, Ming-Jer; Lin, Ching‐Yuan; Chuang, Ying-Ji

doi:10.1016/j.matdes.2008.05.022

Cited by 14 publications

(2 citation statements)

References 9 publications

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“…Consequently, evaluating the mechanical properties of wood bonding under elevated temperatures. Many studies have conducted tensile tests to analyse the shear behaviour of these structures employing various types of wood, adhesives, and temperature ranges [32][33][34][35][36][37][38][39][40][41][42]. However, no studies of wood panels bonded with fire-retardant adhesives, with a focus on evaluating their shear strength, have been found.…”

Section: Introductionmentioning

confidence: 99%

Bonding strength of wood adhesives with fire-retardants under elevated temperatures

Silva,

Alves,

Andrade

et al. 2024

Preprint

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The utilization of wood and wood derivatives are growing in building construction, mainly due to sustainability and circularity reasons, despite the inherent flammability of wood. Woodworking often requires bonding elements with adhesives, which are prone to degradation under fire. A potential solution to improve the fire resistance of wood joints and their derivatives involves incorporating fire retardants into the adhesive compositions. This study explores the adhesion properties of bonded joints of medium-density fibreboard and pinewood panels using resins based on urea and polyurethanes derived from diphenylmethane diisocyanate (MDI). Various proportions of ammonium polyphosphate, borax, and expandable graphite were incorporated as fire retardants. Shear testing was conducted on lap joints under both room and elevated temperatures to evaluate their adhesive performance. At room temperature and 100°C, the predominant failure mode was panel tear failure, while at higher temperatures, cohesive failure became more prevalent. The results indicated a reduction in bonding strength and displacement with increasing temperature. In particular, the MDI-based resin demonstrated higher shear resistance at elevated temperatures in comparison to the urea-based resin. The addition of fire retardants, particularly ammonium polyphosphate, improved the shear strength of MDI joints at 100°C and 200°C. Furthermore, the determined shear modulus per meter evaluated the decreasing rigidity of the bonding joint with increasing temperature. In the reference case of urea without fire retardants, the rigidity of the bond decreased by approximately 100% at 200°C compared to room temperature. In contrast, the MDI cases with ammonium polyphosphate and borax experienced a more moderate decrease of around 60% at 230°C, indicating improved thermal stability.

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Section: Introductionmentioning

confidence: 99%

Bonding strength of wood adhesives with fire-retardants under elevated temperatures

Silva,

Alves,

Andrade

et al. 2024

Preprint

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“…Previous research suggests that the adhesive is the critical element in glued-in rod connections when exposed to elevated temperatures since its capacity decreases drastically when the glass transition temperature (Tg) is exceeded [4][5][6][7]. The latter is defined as the temperature where permanent modifications occur in the molecular structure of the polymer, leading to a transition of a solid to rubberlike state of the adhesive [8][9][10][11]. At temperatures above the Tg, this results in a considerable loss of adhesion and cohesion in the adhesive layer, translating to a poor performance of the connection with an undesirable brittle failure mode [7,[12][13][14][15].…”

Section: Introduction 456mentioning

confidence: 99%

Characterizing the Fire Performance of Adhesives Used in Glued-in Rods Connections

Flores

Dagenais

Blanchet

2023

World Conference on Timber Engineering (WCTE 2023)

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Glued-in rods are an aesthetically and performant type of connection that has seen its usage increase in the last few years. However, there is still a lack of data concerning the fire performance of glued-in rods, limiting its integration in standards. Recent studies suggest that the adhesive is critical to the fire performance of glued-in rods, since its capacity is greatly reduced when the temperature exceeds its glass transition temperature (Tg), ranging between 45-65 o C for most structural adhesives. To validate these findings, dynamic mechanical analysis (DMA) tests were performed to better assess the Tg and other thermomechanical properties of the adhesives used in this research. Axial tension tests at stabilized temperature were performed on 67 glued-in rods specimens using five different adhesives (three epoxies and two polyurethanes) and various sets of temperatures at the glue line interface. Most of these specimens have shown a ductile failure mode for temperatures below the Tg of the adhesive and a brittle failure mode for temperatures above the Tg. This research helps determine guidelines for the fire design of glued-in rods and related testing, and ultimately leading to a design method for providing fire resistance to connections made of glued-in rods.

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Preliminary comparative study on the behaviour of highly-loaded glue laminated timber and wood-CFRP composite beams exposed to local fire

Kawecki,

Pieńko,

Lipecki

et al. 2023

Eur. J. Wood Prod.

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The paper presents a complex solution for testing loaded structural-sized glue laminated timber and innovative wood-carbon fibre reinforced polymers (CFRP) composite beams exposed to local fire. It shows the entire procedure from predicting a static behaviour and a combustion time (from reaching 300 °C temperature of the element up to its fracture) of the tested elements, designing and building an experimental stand, through conducting preliminary tests and discussing the results. The research included combustion of three glue laminated timber (BSH) and three wood-CFRP composite (BSH-CFRP) structural-sized beams in the most loaded section (region of highest bending moment) under three-point bending. A furnace was set under the centre of the beam on one-third of its span. The dimensions of the basket are based on physical properties of firewood providing proper burning conditions of the elements. The self-designed and self-constructed experimental stand enabled applying high load and provided a stable loading during local fire exposure. The preliminary tests showed that using CFRP tapes inside the section may both increase or decrease fire resistance of wooden members depending on the width of wood material covering CFRP tape. CFRP tapes provide a different nature of beam failure, which is changing from sudden fracture (BSH) to plastic flow of the material (BSH-CFRP).

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Effect of fire exposure on the mechanical properties of glued laminated timber

Cited by 14 publications

References 9 publications

Bonding strength of wood adhesives with fire-retardants under elevated temperatures

Bonding strength of wood adhesives with fire-retardants under elevated temperatures

Characterizing the Fire Performance of Adhesives Used in Glued-in Rods Connections

Preliminary comparative study on the behaviour of highly-loaded glue laminated timber and wood-CFRP composite beams exposed to local fire

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