Stages of Resistance of Reinforced Concrete Frames in Accidental Design Situation

The study addresses the stress-strain state stages of reinforced concrete frames in zones of potential local collapse due to failure of a vertical element, such as a column or pylon. The paper provides initial assumptions about the mechanisms of secondary failure propagation in multi-storey reinforced concrete building frames, depending on the initial local collapse scenario. Based on these assumptions, the paper formulates force and deformation criteria for the stress-strain state stages of reinforced concrete building frames in the zone of potential local collapse. Using energy balance conditions, simplified relations were developed to estimate the ultimate static load for compressive arch and catenary actions of floor slab structures. The calculated force and deformation criteria values were compared with the experimental values. These comparisons demonstrate that the accuracy of the proposed relations is acceptable for engineering calculations.