One of the most important directions in the development of additive manufacturing or three-dimensional (3D) printing technologies is the creation of functional materials, which allow not only prototyping but also the manufacturing of products with functional properties. In this paper, poly-lactide acid (PLA) /carbon black (CB) composites with segregated (ordered) structure have been created. Computer simulation based on the Mamunya geometrical model showed that the CB content within φ = 2.5–5 vol.% in the polylactide matrix leads to the formation of a continuous electrically conductive phase with an increase of electrical conductivity σdc above the percolation threshold. The simulation results were experimentally confirmed by optical microscopy and studies of the electrical conductivity of the composites. It was found that increasing CB content from φ = 1 vol.% to φ = 7 vol.% in the composites causes insignificant (due to the segregated structure) phase changes in the polylactide matrix and improves the thermal properties of composites. Electrically conductive filaments for Fused Deposition 3D Printing (FDM) were developed from PLA/CB composites and then 3D printed. A correlation between the electrical conductivity σdc and the CB content φ for base composites, filaments produced from them, and final 3D samples, has been found. Conductivity varies within σdc = 3.1·10−11 − 10·10−3 S/cm for the filaments and σdc = 3.6·10−11 − 8.1·10−4 S/cm for the final 3D-products.

The article presents experimental study results of the deformation state of composite cable space frame structures, including composite steel-concrete structures. Composite cable space frame structures are three-dimensional roof framing of long-span buildings. The designed constructions are a new type of roof framing structures and consist of typical composite steel-concrete modules connected with steel cable elements. The operation of composite cable space frame structures under load is characterised by geometric nonlinearity. The aim of the research is to study the deformation state and changing the geometric shape of experimental structures under the influence of external load. The technique of studying the deformation state of the composite cable space frame structures is based on the principles of digital photogrammetry. At the limit state the composite cable space frame structures change their regular shape. In this case, the central vertical points get the greatest vertical displacements, and the displacement value decreases closer to the supports. It is defined that the investigated construction has demonstrated combined action of all its components during the test, which indicates its effectiveness. The application of the photogrammetry method made possible to determine the moment of reaching the limit state of the composite cable space frame structures concretely.

Abstract. Nowadays new trends are clearly manifested in building structures for buildings of various appointment and specific characteristics of their long-term operation. The priority in the construction industry takes place construction of high-rise residential and office buildings. Numerous studies in Ukraine and abroad proved that the construction of the frame with girderless floor provides resistance to both vertical and horizontal loads. It makes it possible to improve the traditional methods of frame building design. However, in the monolithic building of girderless floors there are a number of unresolved problems of structural, technological and organizational character. The authors have developed the construction of prefabricate reinforced concrete girderless floor that includes column drops, intercolumn slabs, span slabs. Column drops have bevelled lateral edges around the perimeter, forming a platform to support intercolumn slabs. Mounting of slabs occurs in the definite order. In the capacity of the columns it can be used as traditional prefabricated reinforced concrete structures as concrete filled steel tube ones. The advantage is that, comparing to modern reinforced concrete girderless floor, additional supporting equipment is not used during mounting slabs and scaffolding. The proposed girderless floors can be recommended for use in the construction of residential and public buildings for various purposes.

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