Sandwich beams that are composed of laminated face sheets and aluminum pyramidal truss cores are considered to be essential elements of building and aerospace structures. In this paper, a methodology for the experimental and numerical analysis of such structures is presented in order to support their industrial application. The scope of the present research covers both the experimental and numerical extraction of the dynamic parameters of the sandwich beams. Vibration tests are performed while using an optical system for three-dimensional vibrations sensing. The in-plane and out-of-plane vibration modes can thus be examined. A detailed numerical model of the sandwich beam is developed, including an adhesive joint (an additional layer of material) between the parent components of the beam. The numerically predicted modal parameters (eigenfrequencies, mode shapes, modal loss factors) are comported with their corresponding experimentally-obtained values. The modal loss factors are predicted based on the strain energy method, for which a brief theoretical introduction is provided. The obtained experimental and numerical results coincide with good accuracy. The circumstances for possible model simplifications are provided depending on the solution objectives.

There are multiple obstacles associated both with technology and properties of waste ceramic aggregate concrete preventing its wide production and application. In the research programme these limitations were addressed through utilizing steel fibre reinforcement and the phenomenon of internal curing. After laboratory tests of mechanical properties a numerical analysis of composites in question was conducted.

This paper presents the possibility to apply numerical simulation in static analysis of reinforced concrete structure strengthened with carbon fibre reinforced polymer composite strips (CFRP). Reinforced concrete beams, with strengthening in form values CFRP made of carbon fibres and epoxy resin, featuring various width, as well as non-strengthened bent beams, were analysed. The simply supported beams arranged in a free support scheme were subjected to two concentrated forces within full range of loading (until collapse). The numerical analysis was performed through application of the Finite Elements Method (FEM), and the calculation model applied took into account the geometric and physical nonlinearity. The problem was solved by application of the quasi-static strategy method of calculations using ABAQUS software. While analysing the results, we focused on the run of changes in structure displacement and development of material damage, up to the point of destruction of the beam.Key words: reinforced concrete structures, strengthening, composite strips, Finite Elements Method. IThe development of composite materials is the reason that more and more frequently structures made of traditional and composite materials become solutions for engineering problems pertaining to, among other things, strengthening of building structures [1]. A method that is frequently used for this purpose is application of CFRP strips made of carbon fibres and epoxy resin. Increase of interest in such composite materials originates from their extensive usefulness. They feature, among other, several times higher tensile and fatigue strength, compared to structural steel, associated with good chemical resistance, low unit weight, ease easy strengthening and modest outlays on maintenance of composite structure elements. The modulus of CFRP elasticity falls within the range from 150 GPa to 270 GPa, which allows the selection of strips of proper elasticity depending on the cross-section operating conditions.

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