EM - Escola de Minas
URI permanente desta comunidadehttp://www.hml.repositorio.ufop.br/handle/123456789/6
Notícias
A Escola de Minas de Ouro Preto foi fundada pelo cientista Claude Henri Gorceix e inaugurada em 12 de outubro de 1876.
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3 resultados
Resultados da Pesquisa
Item Refined elastoplastic analysis of plane steel frames under extreme dynamic loading.(2015) Silva, Andréa Regina Dias da; Batelo, Everton André Pimentel; Silveira, Ricardo Azoubel da MotaThere 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.Item Second-order plastic-zone analysis of steel frames – Part II : effects of initial geometric imperfection and residual stress.(2009) Alvarenga, Arthur Ribeiro de; Silveira, Ricardo Azoubel da MotaThe application of a second-order plastic-zone formulation to study the minimum requirements needed to arrive at the so called advanced analysis concept, where an individual member’s check is simplified or even unnecessary, is presented in this paper. A companion paper provides the theoretical background for this formulation. These requirements appear in specifications and refer to the unavoidable imperfections of steel structure construction leading to premature collapse. The structure’s out-of-plumbness and members’ out-of-straightness form the initial geometric imperfections, affecting building stability and lateral drift, but are justifiable under manufacturing and erection tolerances. Unequal cooling of a steel section, after the rolling or welding process, creates residual stress that increases the plasticity path. As the plastic zone analysis accounts for these three imperfections in an explicit way, alone or combined, this study shows a brief review, computational implementation details and numerical examples. Finally, this work makes some recommendations to find the worst initial imperfect geometry for some loading cases.Item Second-order plastic-zone analysis of steel frames. Part I: numerical formulation and examples of validation.(2009) Alvarenga, Arthur Ribeiro de; Silveira, Ricardo Azoubel da MotaThis paper presents a second-order plastic-zone formulation for the non-linear analysis and design of plane steel frames with geometric imperfections and residual stress. The proposed numerical methodology has an inelastic formulation based on the plastic-zone method performed by the so-called “slice technique". This methodology also uses a beam-column finite element model based on the Bernoulli-Euler theory and described in the updated Lagrangian co-rotational system. The considered hypothesis and the adopted kinematic relation lead to an element stiffness matrix whose terms represent the constitutive law and second-order effects. An incremental-iterative Newton-Raphson strategy solves the global non-linear equation system and, at the internal force recovery level, in each iteration, an axial-force iterative process is proposed to obtain the axial-force balance at the element ends, more precisely determining the plasticity spread. Three benchmark structural problems are studied and the present work's findings validate the proposed numerical formulation and the axial-force iterative process. A companion paper discusses in depth the influence of geometrical imperfections and residual stress in steel frame design.