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2017-06-07 - Colloque/Présentation - communication orale - Anglais - 26 page(s)

Avez Coralie , Roensmaens Bertrand , Verbist Maxime, Branco Jorge, Descamps Thierry , "A Cohesive Zone Model to study timber-to-steel-plates bonded joints" in ECCOMAS Conference - Computational Methods in Wood Mechanics - CompWood 2017, Vienne, Autriche, 2017

  • Codes CREF : Résistance des matériaux (DI2112), Sciences de l'ingénieur (DI2000), Programmation et méthodes de simulation (DI4317), Résistance et comportement des matériaux (DI2110), Assemblage (DI2133)
  • Unités de recherche UMONS : Génie civil et Mécanique des Structures (F801)
  • Instituts UMONS : Institut de Recherche en Science et Ingénierie des Matériaux (Matériaux)
  • Centres UMONS : Urbanisation Revitalisation Bâtiment Architecture Innovations Espaces (URBAINE)

Abstract(s) :

(Anglais) When designing a wood structure, the capacity of a connection is almost always lower than that of the members it’s linking. Moreover, as minimum distances between connectors or edge distances must be respected, connections can be large and space-consuming. Connections are thus often regarded as the weakest part of a timber structure, and also the most expensive. Hence, finding new connectors and improving existing ones are important issues in the wood construction. Glued connections can constitute an efficient alternative to classical connectors since they exhibit a high strength and stiffness. Moreover, as they are embedded in timber, they are fire-protected. The main drawback of those connections is the lack of design tools and guidelines. This paper outlines the development of a finite element model to predict the strength of a glued connection made of steel plates set parallel to the grain in the central layer of a CLT panel, using a two component epoxy, and tested in tension. The timber slot in which the steel plate is inserted is wider than the steel plate thickness, thus producing a 2.5 millimeter-thick bondline. Apart from its mechanical advantages, this connection is also easy to implement on-site due to its geometry. However, one drawback of this connection lies in the fact that, if the solid steel plate is not textured, the connection may fail at the interface between the steel and the glue, due to poor adhesion between those materials. Although proper surface preparation - mainly degreasing the steel prior to gluing – can guarantee the process of adhesion between the steel and the adhesive, on-site conditions are not conducive to good surface preparation and gluing process. Hence, ensuring mechanical interlock is the best way of preventing adhesion failure to occur. Perforating the steel plate is one way to ensure this mechanical interlock. The presence of perforations filled with the glue enhances the adhesion between the glue and the connector, in comparison with full glued-in steel plates. Moreover, the perforation of the steel plate enables promoting a ductile failure of the connection, by yielding of the steel plate. Thanks to recent progress in CNC machines and laser cutting, now replacing expensive manual milling/drilling, the computerized, cheaper and extremely precise production of such perforated steel plates is now within the realm of the possible. Among the different existing ways of modelling the adhesive thanks to Finite elements, cohesive zone models are chosen. Cohesive-zone model enables modelling the linear elastic response of the joint, the initiation of the damage (fracture criterion) and the damage evolution. The damage is defined using simulation tools already implemented in the software used (commercial package Abaqus). The pros and cons of using this modelling technique are discussed in regards with others FE modelling techniques. Properties experimentally cost- and/or time-demanding to obtain were calibrated and validated on full-scale specimens made of steel plates glued in CLT. Using cohesive damage modelling, the FE model correctly replicates the strength and failure mode of the glued-in perforated steel plate connection tested.