Komfortsanalys med hänsyn till vibrationer orsakade av människoaktiviteter. : Ett modernt dimensioneringsproblem för huskonstruktörer

Sammanfattning:

Comfort analyses regarding human induced vibrations

It is not too common among civil engineers in Sweden to perform comfort analyses considering the vibrations caused by human activities. In addition, the Swedish standards lack requirements to be used for comfort analyses in design of floor-systems. The demand for large spans in combination with slender slabs, is today a reason to investigate the floor-system constructions, in order to prevent disturbing vibrations and oscillations.

The purpose of this thesis is to create a guide for how a comfort analysis, considering vibrations, should be implemented. Göran Svedenbjörk who is an expert in structural dynamics has been interviewed where he presents his latest project Värtaterminalen and answers some questions about vibrations due to human activities.

Floor-systems, consisting of concrete slabs supported by steel or concrete beams, have been investigated with simulations in the finite element program Abaqus. In the simulations, the influence of various factors on the natural frequency of floor-systems and the acceleration level caused by dynamic loads, is studied. Properties like elastic modulus, span width, boundary conditions, density, slab thickness and placement the load have been investigated.

The influence of reinforcement on the natural frequency and acceleration level has also investigated through numerical simulations. The results showed that the additional stiffness from the reinforcement had little effect on the natural frequency of floor-system. It should, however, be noted that the concrete slab was assumed to be uncracked in the numerical models. This means that the reinforcement may have a higher influence on a cracked concrete slab, due to its reduced stiffness. Reinforcement has a larger effect on the acceleration level and in some of the studied cases, the maximum acceleration is reduced with 25%. The stiffness and the mass of the reinforcement result in lower acceleration values. Even prestressed reinforcement effect has been studied in the numerical models. It was found that the effect of prestressed reinforcement is not significantly different compared to regular reinforcement in this context.