Large displacements and instability of beam-like structural systems

Engineering structures when subject to extreme loading conditions may exhibit large deformations and various modes of instability. One of them is due to the material softening that often takes place in reinforced concrete structures. This is classified as the local instability, in contrast to the global instability, which is usually the result of the change of the overall material properties and geometry. In the present lecture the interaction between these two types of instability is described through the study of the behaviour of reinforced concrete structures to destruction. Finally, the behaviour of the two-floor, two-bay concrete frame in fire is presented.