Problem of unilateral constraints in the dynamics of the floor loaded with a machine

The engineering practice indicates that in industrial ferro - concrete constructions there are various irregularities and damages which may hare significant influence on it's stiffness and consequently on it's vibration. In the paper one of fore - mentioned issues i.e. weakening or loss of connection between selected parts of the structure is considered. More precisely it is the problem of unilateral constraints in elastic constraints between the ferro - concrete slab floor and the machine placed on it. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)