Keywords: lightweight, building, modular, parametric, vibration, frequency gap, flanking transmission.

The work described in this paper develops a parametric modelling and analysis approach to investigate the vibration transmission in lightweight buildings. The main focus of the research is to investigate the influence of geometry and configuration of the building on the vibration transmission. A building with a single room in the width direction is modelled, varying the size (length and width) of a room module as well as the numbers of storeys and rooms along the facade.

In the companion paper by Andersen et al. [1], the detailed process of parametric modelling of a modular building is presented. In this paper, vibro-acoustic analysis is performed by means of a simple version of the model, where the entire building is constructed by translation and combination of uniform basic modular elements, i.e. wall and floor panels. Each room is created by selecting the component modules from a predefined group of panels including floor panels, external and internal wall panels, which are considered as beam-stiffened double-leaf panels. To reduce the modelling and analysis cost, the panels are homogenized into equivalent composite shells with two isotropic skin layers and one orthotropic core layer. The material properties of the orthotropic core are obtained from numerical experiments based on a comparison of the results obtained using models employing two-dimensional composite shell elements and three-dimensional solid elements, respectively. An artificial skeleton module is introduced to facilitate the modelling of different connections between panels in the building.

Free vibration analysis is first performed to obtain the distribution of the eigenfrequencies of the building. Then the forced vibration of the building subjected to a mechanical excitation is analysed to investigate transmission of vibration. The influence of different excitation frequencies on the vibration transmission is studied. The response in two different receiving rooms, one near the source and one far from the source, is discussed for various geometric configurations of the building. Some observations can be drawn from the numerical examples:

• Several frequency gaps are observed from the frequency response curve. A quite low response is obtained in these gaps arising from the absence of structural eigenmodes.
• The flanking transmission may play a significant role. The influence on the flanking transmission of introducing a neighbouring room in the direction along the building or on top of the building is discussed.
• The vibration transmission in buildings with different room sizes is analysed and discussed.

It may be concluded that changes to a building structure by means of reducing or increasing the number of modules or the size of modules in a given direction can have a significant impact on the vibro-acoustic performance of the building. Hence, a modular, parametric finite element model can be very useful for design purposes.

1

L.V. Andersen, P.H. Kirkegaard, K. Persson, N. Kiel, B. Niu, "A Modular Finite-Element Model for Analysis of Vibration Transmission in Multi-Storey Lightweight Buildings", in B.H.V. Topping, (Editor), "Proceedings of the Eleventh International Conference on Computational Structures Technology", Civil-Comp Press, Stirlingshire, UK, 2012. doi:10.4203/ccp.99.189

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