Experimental investigations and numerical simulations of the vibrational performance of composite timber-lightweight concrete floor structures

•The dynamic characteristics of timber floor structures can be improved by coupling timber beams and lightweight concrete.•The fundamental frequency of t ested composite beams increases with decreasing volumetric density of lightweight concrete.•The lightweight concrete slab can be sufficiently coupled with timber beams and achieve a fundamental frequency of 10 Hz.•In the case of tested composite beams a satisfactory value of the fundamental frequency was achieved by using lag screws. The dynamic behavior of timber and lightweight concrete composite floor structures was examined in this paper. The need to reduce the additional load on the existing foundations of the structure, leads to the increasing use of lightweight concrete in the rehabilitation and reconstruction of buildings. The aim of this paper is to examine the basic dynamic characteristics of timber floor structures repaired with lightweight concrete of various volumetric densities. The dynamic behavior was analyzed in a way that the first three natural frequencies of four floor composite structures with identical cross sections and fasteners, but with different class of lightweight concrete volumetric density in the upper concrete slab, were calculated. Preliminary laboratory testing of the relevant properties of four types of lightweight concrete, timber and fasteners, which were used in the bonding of timber and lightweight concrete, provided the necessary input data for numerical research. For analytical research, a simple method of dynamic calculation of natural frequencies of elastically coupled structures has been proposed. The accuracy of the results of the proposed dynamic calculation was confirmed experimentally, and by comparison with the results of the Ansys software package.