Determination of the survivability parameters of a reinforced concrete spatial frame operating under conditions of a complex stress state

The calculation for stability against progressive collapse in a dynamic setting, regulated by the norms, contains general recommendations on the possibility of taking into account a pliable foundation and including non-load-bearing elements in the calculation model without determining the limits of their applicability. The results of experimental studies and numerical analysis of a reinforced concrete experimental design of a spatial frame - a fragment of the frame of a multi-storey building in limiting and transcendental states are compared. The features of deformation of the structural system before and after the beyond-design impact, which causes its sudden structural restructuring, are established. Numerical studies were performed with and without considering the pliable foundation, as well as including or not including non-load-bearing elements in the calculation. Satisfactory agreement between the data of experimental studies and the results of dynamic calculation has been obtained. As one of the variants of the calculation model, a modified scheme was adopted, the constituent part of which are the elements of the calculation model of the second level - a fragment of the frame, modeled by volumetric and flat finite elements. It has been established that the results of the dynamic calculation of the experimental fragment are consistent with the experimental data only when taking into account the elements of the load device and real boundary conditions, including the deformable base.