Avaliação da rigidez de pórticos tridimensionais de concreto armado / Evaluation of stiffness in three-dimensional frames of reinforced concrete

AUTOR(ES)
DATA DE PUBLICAÇÃO

2009

RESUMO

An evaluation of stiffness in three-dimensional frames is important to ensure safety in structural projects, especially in tall buildings, where both ultimate limit state and serviceability limit state have to be considered. In reinforced concrete buildings, this evaluation is calculated through an analysis of global stability, either through approximate methods, determining the parameter of instability α and γz parameters or by more demanding methods, for example, using the P-Δ analysis. This work aims to contribute to an evaluation of strength in reinforced concrete frames. It considers a few factors which the author deems relevant to the analysis such as: 1. the tri-dimensional aspect of the structure. 2. the combined interaction of slabs, beams and columns. 3. the plastic collapse load factor. 4. the critical load factor. 5. natural frequencies. Using numerical models based on the method of finite elements (FEM), software programs were developed in Fortran language. They allow an evaluation of the behavior of frames in an incremental elastoplastic analysis, in an elastic stability analysis and in one of natural frequencies under free vibrations. Correlations are presented among all of the involved parameters, which were obtained from the simplified methods ( α and γz parameters) and from the more rigorous methods (λc, λcr e ω), using FEM. These software programs are used in actual building structures and show the degree of influence of each parameter which contributes to the stiffness of the structural framework.

ASSUNTO(S)

vibrações livres pórticos reinforced concrete frames mef free vibrations stability estabilidade fem concreto armado estruturas

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