Robustness of reinforced concrete frames with elements experiencing bending with torsion

Abstract

The article presents the results of experimental and theoretical studies of deformation, cracking and fracture of frame structural systems under accidental impacts. The elements of frame structures may exhibit bending with torque as a consequence of the occurrence of an abnormal event. The study provides an energy-based approach to determining internal forces in such structural systems under a scenario in which a column is removed. It also presents a computational model that evaluates the robustness of a reinforced concrete frame of a multi-story building. The model permits the determination of dynamic effects within a structural system, at varying levels of static loads acting within it, and enables the investigation of deformation patterns within the spatial cross-section, including those experiencing bending and torsion. It also allows for the calculation of the robustness parameter of frame systems. In order to validate the proposed computational model, the study employs the outcomes of tests conducted on scale models of reinforced concrete frames with beams subjected to bending and torsion. The experimental frames were loaded in two stages. In the initial stage, the frame structures were subjected to static loading. At the second stage, scaled models were exposed to dynamic loading, which was caused by the sudden removal of columns. A comparison of calculated and experimental results for the investigated structures demonstrates the reliability and efficiency of the proposed calculation model. Consequently, it can be used to calculate the progressive collapse resistance of reinforced concrete frames of multi-storey buildings.