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  An investigation of influence of construction methods on dynamic response of long-span residential timber floors

   School of Computing, Engineering & the Built Environment

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  Dr A Khokhar, Dr Andrew Livingstone, Dr R Hairstans  No more applications being accepted  Funded PhD Project (UK Students Only)

About the Project

Residential timber floor systems are usually composed of a series of long span timber joists (eg. engineered I-joist or Laminated-Veneer-Lumber) which support wood-based sheathing. This produces a lightweight two-way rib-stiffened structural system. Due to this, timber floors have a tendency to produce high level of vibration when excited by human footfalls. When such high amplitude of vibration occur they can cause discomfort for the occupants. High level of vibration is strongly influenced by the span of the joists and the across-joist (transverse) construction details. Enhancing stiffness in the transverse direction has been found to be an effective means, at some extent, of mitigating excessive vibration levels in timber floors systems [1]. Various construction methods have been introduced to increase the transverse stiffness. Examples of such are reducing the spacing of floor joists, adding extra layer of wood sheathing or concrete topping or adding additional partition walls. Moreover, investigators have reported that adding a row of between-joist bracing spin along the width of floor at mid-span is the most economical and effective approach [2]. However, despite their widespread application the mechanisms by which above construction parameters function has not been fully elucidated. Hence, their performances have not been optimized. The overarching aim of the project is to investigate the influence of optimum effectiveness of construction parameters and level of fixity to obtain satisfactory vibrational performance timber floors built with long span I-joists. This will be delivered by experimental and numerical approaches. It is widely known that controlling static deflection under a point load at floor centre and increasing natural frequencies are a reliable indicator of vibrational serviceability of timber floors [3]. Therefore, a series of floors with different spans will be tested under static and dynamic loads. Influence of geometric arrangements and rigidity of construction parameters to joists will be studied. These tests will assist in looking at how modification in construction parameters enhance the transverse stiffness and to what extent this influences on static deflection and natural frequencies of floors. Based on test results, analytical and numerical models will be developed to investigate further on the vibrational performance of timber floors. The results from experimental and numerical study will be used to develop a generalised approach that can be used in predictive models to calculate structural response of timber floors to static and dynamic loading conditions and can be incorporated into a design procedure for controlling vibration in residential timber floors. This research will provide an in-depth understanding of vibrational performance and user comfort of residential timber floors built with engineered joists. This could be a valuable contribution in timber structures, especially, for industry and for design codes.

Academic qualifications

A first degree (at least a 2.1) ideally in Civil Engineering with a good fundamental knowledge of timber structures.

English language requirement

IELTS score must be at least 6.5 (with not less than 6.0 in each of the four components). Other, equivalent qualifications will be accepted. Full details of the University’s policy are available online.

Essential attributes: · Experience of fundamental in conducting laboratory tests · Competent in Structural analysis, structural dynamics and structural mechanics · Knowledge of timber as an engineering material, test standards · Good written and oral communication skills · Strong motivation, with evidence of independent research skills relevant to the project · Good time management Desirable attributes: Knowledge of timber floor construction, design and structural behaviour

Funding Notes

Payment of the Home/EU level of full-time fees for three academic years, plus 36 monthly stipend payments at the prevailing rate set by the Research Councils


[1] Onysko., DM. 1985. “Serviceability criteria for residential floos based on a field study of consumer response” Project 03-50-10-008, Forintek Canada Corporation, Ottawa, Canada. [2] Khokhar, A., Chui, Y., & Smith, I., 2019. “Influence of between-joists bridging elements on static and dynamic response of wood joisted floors”. Engineering Structures, 188, 362-368 [3] Smith. I. & Chui. Y., 1992. “Construction methods for minimizing vibration levels in floors with lumber joists” Canadian Journal of Civil Engineering. 19,833-841.