The effect of increased deformability of columns on the resistance to progressive collapse of buildings

The article discusses two constructive schemes of the building: two 20-storey buildings, in one model, columns with indirect reinforcement were used, in the other model, longitudinally reinforced columns were used. The calculation was carried out in the software complex Lira SAPR 2015. In the calculation, the finite element method was used in the form of the displacement method. The transition from the continual real model of structures to a discrete computational scheme was carried out by dividing the model into finite element grids with a step of no more than three element thicknesses, the number of degrees of freedom of FE is six. The limit state of reinforced concrete, which characterizes the work of structures in the stage of destruction, the "special" limit state, is considered. A particular limit state is characterized by partial destruction of the structure, but in which there is a resource of residual deformation, necessary for the redistribution of efforts arising from an emergency. Analyzing the calculations of the deformation and strength characteristics of the material with indirect reinforcement according to the normative document, it can be concluded that the characteristics of the material correspond to the operation of the structures when the "special" limit state is reached. The sufficient convergence of the data of the results of research of elements with indirect reinforcement and the theoretical results of calculation according to the normative document is established, which allowed in the modeling to make full use of the resources of elements with indirect reinforcement. © Published under licence by IOP Publishing Ltd.