A two-scale FE model to address connections in coupled fire-structure simulations

A two-scale finite element model is proposed to improve two-way coupled fire-structure simulations. The model consists of (i) a global-scale model, which accounts for the structure, and (ii) a small-scale model for each connection. Structural parts on the global scale are connected by spring elements, which stiffness properties are updated by the small-scale models. A sandwich panel system, fixed with four screws, and exposed to fire, is simulated for demonstration purposes. The simulation shows that the two-scale model is able to transfer the mechanical response of the small-scale model, including failure, to the global-scale model. As soon as all screw connections fail, the panel is assumed to fail, and is removed in a subsequent part of the fire simulation. It is then demonstrated that the fire scenario changes from ventilation-controlled to fuel-controlled. Future research will incorporate more complex structures, and verification by experiments.