Vibrations of metal web joist timber floors with strongbacks

Binsheng Zhang, Abdy Kermani, Tony Fillingham

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This research aims to assess the effects of joist spacing, strongbacks and ceiling on the dynamic response of the timber floors with metal web joists so as to evaluate the vibrational design criteria, e.g. modal frequencies, modal shapes, damping and unit point load deflection, required by EC5-1-1 and the UK NA for timber floors. In general, joist spacing, strongbacks and ceiling do not largely influence the fundamental frequency and damping ratio, but affect higher modal frequencies. The measured damping ratio for the fundamental mode is 0.86% on average. The use of strongback considerably reduces the number of first order modes below 40 Hz, and causes easier fulfilment of velocity design criterion. The test results indicate that the decrease in joist spacing, the increase in number, size and stiffness of strongbacks, and the use of ceiling all largely reduce the maximum displacement of the floors. On average, the calculated displacements based on the equations in the UK National Annex are close to those measured.
Original languageEnglish
Pages (from-to)549-562
Number of pages14
JournalStructures and Buildings
Issue number8
Early online date12 Jul 2016
Publication statusPublished - Aug 2016



  • codes of practice & standards; dynamics; timber structures

Cite this

Zhang, B., Kermani, A., & Fillingham, T. (2016). Vibrations of metal web joist timber floors with strongbacks. Structures and Buildings, 169(8), 549-562.