Different modelling approaches to coupling wall and floor panels within a dynamic finite element model of a lightweight building

As a result of the increasing interest of constructing environmentally friendly lightweight buildings, analyses of vibrational and acoustical transmission in these buildings have become increasingly important. Structures where vibrational transmission may result in undesirable vibrations with possible sound emission as a consequence, must be avoided. A parametric modular finite element model has been developed for this purpose as described in a companion paper presented at this conference. In [1]. This model is intended as a basis for vibro-acoustic analysis of lightweight buildings.With the number of modules in the three axial directions defined, wall and floor panels are constructed, placed and coupled in the global model. The core of this modular finite element model consists of connecting the different panels to each other in a rational manner, where the accuracy is as high as possible, with as many applications as possible, for the least possible computational cost. The coupling method of the structural panels in the above mentioned modular finite element model is in this paper discussed and evaluated.The coupling of the panels are performed using the commercial finite element program ABAQUS [2], where the built-in element constraints applications are utilised. The models are setup in scripts, using the Python language, to ensure a fast and consistent model.It is found that the modules, i.e. panels, are easy to couple, if an auxiliary skeleton is introduced in all panel intersections. In this way a well-defined master geometry is present onto which all panels can be tied. But as the skeleton is an element itself, it will have a physical mass and a corresponding stiffness to be included in the linear system of equations. This means that the skeleton will influence the structure with an increased overall mass and stiffness. This influence is quantified with the aim to reduce it to a minimum.By selecting a small profile, low stiffness and an insignificant mass for this skeleton, the effects of the non-real structure are limited and the structural response resembles the response of a similar construction without a skeleton. These parameters are selected in a way where decoupled pseudo-modes of the skeleton are avoided, alongside the insignificant influence of the overall structure achieved with a low mass, small profile, and a relatively low Young's modulus, approximately 1/30 of the value used for the panels. The problem with the pseudo-modes is further reduced, by choosing similar mesh refinements in both the skeleton and the panels. This will also ensure a converging model.