Dynamisk analys av betonghåldäck : Parametrisk FEM studie

Sammanfattning: Hollow-core concrete slabs can be used in buildings to achieve longer floor spans in comparison to regular concrete slabs. However, longer floor spans in combination with low dead-weight make them more susceptible to vibrations.Frequencies between 0-15 Hz are relevant to study since these lower frequencies affect the comfort of humans. Specifically, the first frequency in this interval is crucial when considering the comfort.This thesis studies how the modelling of the dynamic in a hollow-core slab could be done. This is conducted by modelling and comparing isotropic and orthotropic shell models with a more advanced solid model. The modelling of the HC slab is done in the FEM program Brigade. The first frequency in the above-mentioned interval is analyzed and compared in all models to study whether shell models, instead of a solid model, is viable for the modelling of a HC slab with varying dimensions.Various verifications were executed when modeling where, among other things, the boundary conditions were verified. This was done through comparison of the first frequency in a homogenous solid model, an isotropic shell model and a theoretically calculated frequency. This verification was conducted with boundary conditions firstly placed in the middle and then the lower edge of the slab. All the above was to make sure that the boundary conditions in the shell and the solid models corresponded to each other.The result of the study shows that the orthotropic shell model is not always the most ideal representation of the dynamics. The conclusion is therefore that an isotropic shell model is good enough for the modelling of a HC slab’s dynamics.