Affiliations: School of Architecture, Landscape and Civil
Engineering, University College Dublin, Belfield, Dublin, Ireland
Note: [] Corresponding author: A. Devin, University College Dublin,
School of Architecture, Landscape and Civil Engineering, Belfield, Dublin 4,
Ireland. E-mail: austin.devin@ucd.ie
Abstract: Structures include elements designated as load bearing and non-load
bearing. While non-load bearing elements, such as facades and internal
partitions, are acknowledged to add mass to the system, the structural
stiffness and strength is generally attributed to load bearing elements only.
This paper investigates the contribution of non-load bearing elements to the
dynamic response of a new structure, the Charles Institute, in the grounds of
University College Dublin (UCD) Ireland. The vertical vibration response of the
first floor and the lateral response at each floor level were recorded at
different construction stages. The evolution of the structural response as well
as the generation of a finite element (FE) model is discussed. It was found
that the addition of the non-load bearing facades increased the first floor
natural frequency from 10.7 Hz to 11.4?Hz, a change of approximately
+6.5%. Similarly these external facades resulted in the first sway mode
having its frequency increased by 6%. The subsequent addition of internal
partitions, mechanical services and furnishings resulted in the floor natural
frequency reducing to 9.2 Hz. It is concluded that external facades have the
net effect of adding stiffness and the effect of internal partitions and
furnishings is to add mass. In the context of finite element modelling of
structures there is a significant challenge to represent these non-structural
elements correctly so as to enable the generation of truly predictive FE
models.
Keywords: Operational modal analysis, frequency domain decomposition, non-structural elements
