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The final thesis „Explicit and Implicit methods in nonlinear dynamics“ deals with the issue of geometrical and physical nonlinear analysis of structures exposed to seismic loading by the methods of direct integration of equations of motion. Solution by the explicit and the implicit method is compared for three material models. While the differences between the results of the explicit method and the implicit Newmark method are small as expected, the differences are substantial between the results of different material models. However, these differences are explained and they are in full concordance with the theoretical assumptions for the pertinent material models. The conclusion of the final thesis is check of correctness of the results of the new module of the program system RFEM for both tested numerical methods and all three analyzed material models. (linear elastic, plastic Drucker-Prager and the Mazars damage model). With sufficient precision of results, both explicit and implicit numerical methods showed to be suitable for seismic analysis. The implicit method can provide several times faster calculation than the explicit one, but the determination of the optimal time step is problematic and time consuming, so the suitability of use of both methods for seismic analysis is comparable.

Orientador: Aloisio Ernesto Assan / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Civil / Made available in DSpace on 2018-08-09T14:51:33Z (GMT). No. of bitstreams: 1 MarinsNeto_Joaquim_D.pdf: 2657521 bytes, checksum: 0ec05538330e19307c02836f16d53382 (MD5) Previous issue date: 2007 / Resumo: Neste trabalho são estudados os aspectos das propriedades do concreto, das propriedades do aço e das interações entre eles, com particular interesse na deterioração da aderência que ocorre na interface aço-concreto, para a análise numérica de estruturas de concreto armado. O objetivo principal é o desenvolvimento de uma modelagem numérica capaz de investigar, de forma mais realista, o comportamento de vigas de concreto armado, considerando a não-linearidade física dos materiais e os efeitos do deslizamento entre a armadura de aço e o concreto. Com o Método dos Elementos Finitos e com um procedimento incremental-iterativo de carregamento, os comportamentos dos materiais puderam ser facilmente representados na modelagem numérica computacional, possibilitando o uso de diferentes curvas representativas das tensões de aderência que se opõem ao deslizamento da armadura. A análise crítica foi feita comparando, através de exemplos numéricos, a modelagem numérica desenvolvida neste trabalho com outras encontradas na literatura e com ensaios experimentais, mostrando os excelentes resultados e a eficiência da proposta aqui apresentada / Abstract: In this work aspects of the properties of the concrete, steel and the interaction between them, with particular interest in the deterioration of the bond that occurs in the steel-concrete interface that are necessary to the numerical analysis of reinforced concrete structures are studied. The main aim of this research is the development of a numerical model to simulate the reinforced concrete beams behavior, considering the nonlinear material and the effects of the slip between the reinforcement steel and the concrete. With the Finite Element Method and increment-iterative techniques, the behavior of the materials could be easily represented in the computational numerical model proposed, allowing the use of curves based on the stages of relationship between the local bond stress and the relative slip of the bar. The critical analysis have been done comparing the numerical model developed in this work with other numerical models and with experimental works, showing excellent results and very good efficiency of the present proposal / Doutorado / Estruturas / Doutor em Engenharia Civil