Refined elastoplastic analysis of plane steel frames under extreme dynamic loading.

Abstract

There may be situations in which structures are subjected to dynamic loads with intensities sufficient to cause permanent deformation and to accumulate damage that leads to collapse. Under extreme loading these structures must be capable of absorbing a considerable amount of energy. Thus, if engineers are to conceive lighter, more slender constructions without compromising quality and security standards, then they must evaluate a structure’s dynamic behavior considering the material ductility. Complex theories such as nonlinear formulations can be used to reduce simplifications in the analysis/design process. This work evaluates the nonlinear behavior of plane steel frames under extreme dynamic loads. Steel is considered to be an elastoplastic material, and for loading/unloading conditions, the structural members’ plasticity state is controlled using the refined plastic-hinge method. With this refined method the cross section’s gradual plastification can be accompanied from the start of yielding until the complete plastification of the section (plastic-hinge formation). Residual stresses are also considered, and the adopted plastic resistance surface of the cross section is defined by the internal forces and by its geometric characteristics. The numerical examples presented demonstrated the applicability of the proposed numerical strategy where the refined plastic hinge model enables the energy dissipation through the plastic hinges.