VIBRATION PERFORMANCE OF FLAT PLATE CONCRETE FLOORS WITH CODIFIED MINIMUM THICKNESS
Keywords:Concrete floor, Deflection, Natural frequency, Vibration, Human comfort
Limiting vibrations to ensure occupant comfort is a serviceability requirement that should be considered in the design of floor systems. Current concrete design codes do not explicitly address the issue of vibrations when providing guidelines for calculation of the slab thickness of a flat plate floor. Concrete codes have introduced several methods of determination of the slab thickness or span-to-thickness ratio on the basis of deflection control. The objective of this article is to investigate to what extent a flat plate floor with codified minimum thickness would meet the requirement for walking-induced vibration control. The modal properties of flat plate floors spanning 6-9 m were determined and the 90th percentile velocity response to walking excitation was calculated using probability-based design charts developed by a European guideline on floor vibrations. For deflection control, on average the floor designed following the European concrete code was 6% thinner than the floor designed using the American concrete code and 34% thinner than the floor designed according to the Australian concrete code. It was interestingly found that the vibration of a floor that was dimensioned for deflection control as per any of the three concrete design codes well met the acceptance criteria for human comfort in office buildings, residential buildings, hotels and schools. In addition, the vibration of a 9-m-span floor whose slab thickness was determined using the Australian concrete code provisions could even be acceptable for critical areas.