Abstract
Analytical, experimental and numerical results of determination of natural frequencies and forms of oscillations of reinforced concrete and fiber-reinforced concrete hollow core slabs are given. The problem of determination of natural frequencies and forms of oscillations of reinforced concrete and fiber-reinforced concrete slabs at the initial modulus of elasticity is solved analytically. Computer modeling of the considered constructions in two software complexes is performed and the technique of their modal analysis on the basis of the finite element method is developed. Experimental researches of free oscillations of the considered structures are carried out and the comparative analysis of all received results is carried out. The frequency spectrum calculated by the finite element method (ANSYS) is approximately 4% lower than calculated analytically; the results of the calculation in SOFiSTiK differ by 2% from the results obtained in ANSYS; the discrepancy with the experimental data reaches 15%, and all frequencies calculated experimentally, greater than the frequencies calculated analytically or by the finite element method. The obtained frequency range of fiber concrete slabs is higher than that of concrete, which gives reason to recommend fiber-reinforced concrete for the manufacture of structures that will work under dynamic influences.
Keywords