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Theses

Caractérisation et modélisation du comportement au feu de poutres en bois lamellé collé

Abstract : Wood is increasingly being used as building rnaterial due to its specific characteristics, such as its high insulating capacity given by its low thermal conductivity. Nowadays, wood may be considered as an answer to the cUITent energy cri sis, resulting in cost reduction in energy consumption. Wood is classified as a combustible material, which makes us doubt about its structural tire resistance. However, contrarily to !bis idea and spite of its classification, wood provides an excellent tire resistance. It bas long been recognized that under a tire situation, a wood structure loses resistance more slowly than a steel or concrete structure. The particular context of this study relates to tire applied to glulam. Currently, the most used adhesives in the glulam industry are: Resorcinol-Formaldehyde, Phenol-Resorcinol-Formaldehyde, Urea-Formaldehyde, and MelamineUrea-Formaldehyde. The main problem arising from these adhesives is their two-component fonnulation (adhesive and hardening), making their usage more complicated. Moreover, wood bas to be dried before gluing, which in turn increases the costs and building time. ln order to solve these inconveniences, there are currently other solutions in the market, e.g. Polyurethane adhesives consist of only one liquid component applied directly on wood even if it is wet. However, this kind of adhesive shows a high level of creep at high temperatures, which rnay lead to a dangerous situation during a tire. ln the development of !bis thesis, we characterized the behavior of structural polyurethane adhesives under tire, considering as parameter for comparison the most used adhesives, i.e. Phenol-Resorcinol-Formaldehyde and MelamineUrea-Formaldehyde. As a first stage we characterized the different adhesives subject to high temperatures (between 30°C and 250 °C). As a second stage we established the tire behavior of glulams under the different studied adhesives. For !bis, we chose to perfonn tests with a radiant panel at constant flow (15, 25, 45 and 60 kW/m2). The main result was that the kind of adhesive used in glulams bas no influence on tire resistance. The final stage of fuis study consisted on modeling the different occurring phenomena: A thermal model through a finite element allowed to follow-up in time the temperature distribution in the glulam transversal section subject to a heat flow. By integrating the stiffness database and the elasticity modulus resulting from the creep tests, we have been able to predict the creep behavior and failure time for a glulam subject to a temperature flow that simulates a tire. The results agree with the tests and show that the kind of adhesive bas no influence on tire resistance as the char layer that forms in the glulam surface is a good insulator that limits the depth of the wood darnaged by temperature and thus, its loss of mechanical resistance.
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Theses
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http://docnum.univ-lorraine.fr/prive/SCD_T_2006_0099_FERNANDEZ.pdf
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https://hal.univ-lorraine.fr/tel-01746596
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Submitted on : Thursday, March 29, 2018 - 10:40:58 AM
Last modification on : Tuesday, March 10, 2020 - 2:11:16 PM

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  • HAL Id : tel-01746596, version 1

Citation

Cristian Fernandez. Caractérisation et modélisation du comportement au feu de poutres en bois lamellé collé. Autre. Université Henri Poincaré - Nancy 1, 2006. Français. ⟨NNT : 2006NAN10099⟩. ⟨tel-01746596⟩

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