Critical review of guidelines for checking vibration serviceability of post-tensioned concrete floors

As spans and slenderness of post-tensioned concrete office floors increase, their vibration behaviour is becoming increasingly important. Although now recognised worldwide to be an important design issue, detailed guidance on the checking of the vibration serviceability of post-tensioned floors is not readily available in national building codes of practice. The only detailed guidelines developed worldwide specifically for checking vibration serviceability of post-tensioned office floors have been published by the UK Concrete Society in 1994. These guidelines are generic, could be and are being used in countries where specific national guidance is lacking. However, the Concrete Society guidelines have been found to be problematic in each of the three key aspects of floor vibration serviceability assessment. First, in the modelling of walking excitation, an unrepresentative walking forcing function is assumed. Second, as the guidelines were not experimentally verified, some unwarranted assumptions and simplifications are made in the modelling of the floor structure, in particular its boundary conditions. Finally, the method of calculation of the floor responses is somewhat simplistic. Here, the possibility that modes of vibration higher than the fundamental may be excited in resonance by walking is neglected