Thermo-hydric transfer within dowelled and bolted timber connections under fire exposure ; Etude de l'influence des transferts thermo-hydriques sur les composants d'assemblages bois sous incendie

Abstract

Nowadays, timber structures are well on the way to democratization as regards building uses. They, indeed, present many advantages including light weight, speed of implementation and contribution to sustainable development. These structures are made of timber elements connected together using metal components such as bolts, dowels and nails forming the mechanical joints, which is sometimes reinforced with metal plates. Consequently, the joints are vulnerable areas when exposed to fire. Understanding their mechanical behavior, therefore, is essential, not only as regards fire exposure, but also as regards the coupling of the thermal and hydric fluxes within the connections.As we know, wood is an anisotropic material and relatively humid. The combination of the architectural demand and the material mechanical resistance requires wood materials to cohabit with other materials like steel fasteners. With the presence of steel members, thermo -hydric heat transfer phenomena within joints under fire exposure increase in speed and complexity [4 e7].This complexity comes from the difference between the materials regarding mechanical rigidity and thermo -hydric permeability. It affects the mechanical and thermo-physical properties of the materials eventually, in particular, thermal conductivity and specific heat subjected to the thermal action of fire. With this aim in view, the present research provides important experimental and numerical data, which are needed in the field of understanding and quantifying thermos-hydric transfer phenomenon within timber-steel connections.The objective of this thesis is to present the findings of the investigations carried out to study experimental and numerical thermo-hydric transfer of timber connections subjected to the ISO-834 standard conditions of fire exposure. The experimental part starts by the study of a sin gle bolt or single dowel timber-timber connections under fire. The temperature-time evolutions are measured at different places of the connections. Then two studies are ...