Coupling elements for substructure modelling of lightweight multi-storey buildings

Accurately modelling the dynamic behaviour of multi-storey buildings in wood requires the geometry involved to be represented in great detail, resulting in systems having many millions of degrees of freedom. Consequently, there is a need for model order reduction and the methodology of substructure modelling is employed here to create reduced models for analysis of low-frequency vibrations. The full finite element model of a building is divided into substructures which are reduced in size before being assembled to form the global model. The efficiency of the reduced models is strongly dependent on the number of degrees of freedom at the interface surfaces of the substructures, why it may be necessary to perform interface reduction of some sort. Multi-storey buildings in wood are often constructed with elastomer layers separating the structural components, these offering a natural choice of dividing the buildings into substructures. In this paper, the methodology of introducing a condensation node is adopted for employing interface reduction at the interfaces between the elastomer layers and the structural components in wood. Different methods of coupling the condensation node to the interface surfaces were compared in a test model consisting of a floor–ceiling structure in wood, where the floor and the ceiling are separated by elastomer blocks. It was concluded that a rigid coupling is the most appropriate choice for the interface surfaces of the elastomer blocks, while a distributed coupling provides the most accurate results for the interface surfaces of the floor and the ceiling.