BEARING CAPACITY OF EMERGENCYLY LOADED REINFORCED CONCRETE COLUMNS WITH INITIAL IMPERFECTIONS

An approach to numerical simulation of the stress-strain state of reinforced concrete square columns with various types of initial imperfections is considered. Their ultimate bearing capacity is determined taking into account the possible dynamic additional loading by the longitudinal force and the bending moment. For research, a numerical model is used that describes the design of the column with volumetric elements for concrete and rod elements for the reinforcing cage. Initial imperfections are modeled by physical removal of elements, unzipping of elements, unzipping with the possibility of subsequent stitching by nonlinear bonds that simulate gaps and adhesion at the interface between media. Numerical analysis was carried out in a dynamic formulation according to an implicit scheme based on the direct method, the solution of a nonlinear problem was performed using the Newton-Raphson method with a discrepancy in the value of nodal forces. The degree of influence of initial imperfections associated with deviations of geometry and damage to the material on the bearing capacity of compressed-bent elements under emergency impact has been established. It is shown that for structures