Dynamic modelling of post-tensioned concrete floors using finite element analysis

The only existing guidelines developed specifically for checking the vibration serviceability of slender post-tensioned concrete floors, which are simplified and suitable for hand calculations, have proved to be unreliable. The alternative approach recommended here for checking the vibration serviceability of such floors with high span-to-depth ratios is based on dynamic finite element modelling. This paper presents an experimentally verified set of guidelines for performing such modelling. In particular, it is recommended that band beams and wide, shallow ribs, which are common features in long-span in situ cast post-tensioned floors, are modelled using orthotropic shell elements with smeared stiffness properties, instead of standard beam elements. Also, it has been determined that the bending stiffness of integral columns provides a significant contribution to the overall bending stiffness of the floor and that these should not be modelled as pin supports allowing free rotation, as is currently common practice. The use of bar finite elements to simulate the columns proved to be satisfactory. (C) 2001 Elsevier Science B.V. All rights reserved.