Methodology for Modeling the Survivability of Multi-story Building Frames with Complex Stress Reinforced Concrete Elements

Abstract

AbstractA technique for modeling reinforced concrete monolithic multi-story building frames with complex stress elements is presented to assess the parameters of their survivability under emergency beyond-design actions. The calculation model is built based on a combination of finite element and block calculation schemes. The moment of formation of cracks in the finite element calculation scheme is carried out according to the principal stresses in the volumetric finite elements. In this case, the finite element model is applied without further changing the order and number of volumetric finite elements specified at the beginning. The crack pattern is taken into account implicitly - by reducing the deformation modulus of volumetric elements. To determine the bearing capacity of a complex stress girder, an analytical block calculation model of the second level is used, in which the calculation block is cut off by a progressive spatial crack. The static conditions in this block are provided by the forces in the longitudinal, transverse reinforcement, and compressed concrete. The proposed calculation model provides a low-iteration process for solving the considered nonlinear problem at all loading levels and especially at loads close to failure ones. A numerical calculation of a two-span reinforced concrete frame is given, for which a physical experiment is planned, and its reinforcement is determined under two loading options: an operational load and a special action caused by the sudden removal of the central frame column. KeywordsComplex stress reinforced concreteBuilding frameCalculation modelSurvivabilityModeling techniqueSpecial actions