Mitigating Footfall-Induced Vibration in Long-Span Floors

Abstract

Long-span lightweight floor systems with low damping are susceptible to serviceability problems due to human excitations. This paper discusses two remedial measures to alleviate disturbing footfall-induced vibrations observed on a real office floor of steel-concrete composite construction. One treatment involves stiffening the existing floor beams while the other utilises passive control with an innovative distributed multiple viscoelastic tuned mass damper (TMD) system. Several finite element models reflecting different remedial scenarios are analysed from which the TMD approach and the traditional stiffening technique are found to be comparably effective in reducing the vibration level. However, the proposed TMD solution is far superior, feasible and non-intrusive when applied to existing floors. A probability-based evaluation of the effectiveness of the TMD system is also conducted, taking into account likely variations in the walking force and dynamic properties of both the floor and dampers. The custom-made damper system has been successfully installed on the real floor and performed efficiently in various field tests.