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Structural Engineering and Mechanics
  Volume 58, Number 2, April25 2016 , pages 277-300
DOI: https://doi.org/10.12989/sem.2016.58.2.277
 


Vibration analysis and FE model updating of lightweight steel floors in full-scale prefabricated building
Smiljana P. Petrovic-Kotur and Aleksandar P. Pavic

 
Abstract
    Cold-formed steel (CFS) sections are becoming an increasingly popular solution for constructing floors in residential, healthcare and education buildings. Their reduced weight, however, makes them prone to excessive vibrations, increasing the need for accurate prediction of CFS floor modal properties. By combining experimental modal analysis of a full-scale CFS framed building and its floors and their numerical finite element (FE) modelling this paper demonstrates that the existing methods (based on the best engineering judgement) for predicting CFS floor modal properties are unreliable. They can yield over 40% difference between the predicted and measured natural frequencies for important modes of vibration. This is because the methods were adopted from other floor types (e.g., timber or standard steel-concrete composite floors) and do not take into account specific features of CFS floors. Using the adjusted and then updated FE model, featuring semi-rigid connections led to markedly improved results. The first four measured and calculated CFS floor natural frequencies matched exactly and all relevant modal assurance criterion (MAC) values were above 90%. The introduction of flexible supports and more realistic modelling of the floor boundary conditions, as well as non-structural façade walls, proved to be crucial in the development of the new more successful modelling strategy. The process used to develop 10 identified and experimentally verified FE modelling parameters is based on published information and parameter adjustment resulting from FE model updating. This can be utilised for future design of similar lightweight steel floors in prefabricated buildings when checking their vibration serviceability, likely to be their governing design criterion.
 
Key Words
    vibration analysis; FE model updating; lightweight steel floor; prefabricated building
 
Address
Smiljana P. Petrovic-Kotur: Faculty of Construction Management, University Union Nikola Tesla, Cara Dusana 62-64, Belgrade 11000, Serbia
Aleksandar P. Pavic: College of Engineering, Mathematical and Physical Sciences, University of Exeter, UK
 

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