A METHODOLOGY OF MODELLING THE STRESS-STRAIN STATE OF RIGID CONNECTION JOINTS OF SITECAST REINFORCED CONCRETE CEILING TO CONCRETE FILLED TUBE COLUMN

The methodology of modeling the stress-strain state of rigid connection joints of sitecast reinforced concrete ceiling to concrete-filled column was developed. The construction of ceiling include the external steel reinforcement plates, which works as ceiling-height beams and steel rigid element, which crosses the concrete filled tube core and allows to transfer the loads from the ceiling on the concrete filled column. The modeling was done with the Femap (NX Nastran) software package, using the geometry models, created in the Autocad graphic environment. An edge loads for the rigid connection joint of steel elements of sitecast reinforced concrete ceiling to concrete-filled column was taken from the model of a 40-floor building with the 6m column step, which was modeled in Lira software package. The bending moment from the
ceiling was attached as a distributes pair of forces to the flanges of the external steel ceiling reinforcement plates and the shear force was attached to the steel web of an internal rigid element. As a result of modeling the stress-strain state of rigid connection joints of steel elements of sitecast reinforced concrete ceiling to concrete-filled column, the diagrams of the stress and strain distribution were received. The diagrams of the stress and strain distribution allowed researchers to determine the joint elements working conditions and stress concentrations. The maximum stresses were occurred in the web of the internal rigid element and in the corners of the top flanges of the external steel ceiling reinforcement plates. The analysis of the stresses in the rigid connection joint of steel elements of sitecast reinforced concrete ceiling to concrete-filled column finite element model allowed researchers to optimize the joint with the external stiffeners creation, which allowed to increase the overall connection stiffness. The concrete filled and non-concrete filled tube models comparison was made to receive the concrete filled column core bearing conditions. According to the results of comparison modeling, the concrete core of concrete filled column is included in the column work and bear the 55–60 % of ceiling load.

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