<p> A research program is presented for assessing the plastic collapse load and incremental collapse load of reinforced concrete frames. This investigation attempts to establish a range of validity of simple plastic theory when applied to the under reinforced concrete frames and to determine the sensitivity of such structures to variable repeated loading. </p> <p> An experimental program was conducted on 4 reinforced concrete frames and two reinforced concrete columns. Deflections and strains of these models of nearly prototype size were measured and compared with predicted values at critical cross-sections. </p> <p> Resulting conclusions and recommendations for further research are made. </p> / Thesis / Master of Engineering (MEngr)

[pt] É apresentada uma metodologia para a determinação da carga de colapso e uma outra para o dimensionamento ótimo em vigas de concreto armado. Para a determinação da carga de colapso a metodologia utiliza a análise limite e o modelo da Treliça Clássica de Mörsch. A formulação do problema é obtida a partir dos teoremas limites de plasticidade, que permitem escrever o problema da análise limite na forma de programação linear (PL) e o programa LINGO é utilizado para resolvê-lo. Para o dimensionamento ótimo o mesmo modelo da treliça de Mörsch é utilizado e a formulação do problema também recai num problema de programação linear que pode ser resolvido pelo programa LINGO. A solução fornece tanto as áreas das armaduras longitudinais como dos estribos. Os exemplos apresentados ilustram a validade e eficiência da formulação proposta. Os resultados obtidos são analisados e comparados com os resultados experimentais e com os obtidos com o uso de outra metodologia. Finalmente são apresentadas as conclusões e sugeridas propostas para trabalhos futuros. / [en] Methodologies for the determination of the collapse load and for the optimal design of concrete beams are presented. For the collapse load determination the methodology makes use of the limit analysis and of the classical truss model of Mörsch. The formulation of the problem is based on the limit theorems of plasticity which allow the limit analysis problem to be expressed as a linear programming problem (LP) which is solved by the program LINGO. For the optimal design, the same truss model of Mörsch is used and the formulation also leads to a linear programming problem which can be solved by the program LINGO. The solution yields both the longitudinal reinforcement and the stirrups. The examples presented illustrate the validity and efficiency of the proposed formulation. The results obtained are analysed and compared to the experimental ones and to those obtained using other methodologies. Finally, conclusions are drawn from the results and suggestions are given for future researches in the field.

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