Analysis of various factors’ influence on the interaction forces of the concrete element’s steel case and core

Abstract

Pipe-concrete structures are effectively used in the high-rise and long-span structures’ construction. This complex material has the properties that distinguish them from the conventional metal and reinforced concrete structures. However, the wider use of pipe concrete in construction, despite a large number of studies, is constrained by the lack of documents governing the calculation, design, production process technology and rather significant discrepancies in the experimental data of various authors on determining the interaction forces of the concrete element’s case and core. This is explained by the influence on their size: the method of applying the load (axial or with eccentricity, to the entire cross section or only to the core), its action duration, the ratio of the wall thickness to the cross section size, deformability and strength of concrete, the ratio of steel and concrete amount in the cross section. In this paper, based on the solution of the Lame problem for a circular cylinder, we obtain the formulas for the interaction forces between the core and the case, taking into account various factors. The yield strength of the case steel and the ultimate deformation of the concrete core are accepted as the criteria for the structure’s strength. Axial compression is considered without loss of shape stability, i.e. with a structure length not exceeding the five cross-sectional diameters, which usually corresponds to the length of columns in civil buildings.