The paper develops an isotropic and an orthotropic flat plate models for predicting simply and reasonably accurately the dynamic behaviour
of composite floors. Based on the observation that the mode shapes of a multi-panel floor are different and complicated but the mode shape of
each panel is either concave or convex, the two equivalent flat plate models are developed using the equivalence of the maximum displacement of
a sophisticated 3D composite panel model. Thin shell elements are used to model the steel sheet and 3D-solid elements to represent the concrete
slab. Parametric studies are conducted to examine the effects of boundary condition, loading condition, shear modulus and steel sheet on the
equivalent models. The two simplified flat plate models are then applied to studying the dynamic behaviour of a full-scale multi-panel profiled
composite floor (45.0 m × 21.0 m) in the Cardington eight-storey steel framed building. The predicted and measured natural frequencies are
reasonably close. The modelling process becomes easier and significant time saving is achieved when either of the two simplified models is used.
It is found from the study that the variation of floor thickness due to construction can significantly affect the accuracy of the prediction and the
locations of neutral axes of beams and slabs are not sensitive to the prediction providing that they are considered in the analysis. |
