Contribution to assessing the stiffness reduction of structural elements in the global stability analysis of precast concrete multi-storey buildings

This study deals with the reduction of the stiffness in precast concrete structural elements of multi-storey buildings to analyze global stability. Having reviewed the technical literature, this paper present indications of stiffness reduction in different codes, standards, and recommendations and compare these to the values found in the present study. The structural model analyzed in this study was constructed with finite elements using ANSYS® software. Physical Non-Linearity (PNL) was considered in relation to the diagrams M x N x 1/r, and Geometric Non-Linearity (GNL) was calculated following the Newton-Raphson method. Using a typical precast concrete structure with multiple floors and a semi-rigid beam-to-column connection, expressions for a stiffness reduction coefficient are presented. The main conclusions of the study are as follows: the reduction coefficients obtained from the diagram M x N x 1/r differ from standards that use a simplified consideration of PNL; the stiffness reduction coefficient for columns in the arrangements analyzed were approximately 0.5 to 0.6; and the variation of values found for stiffness reduction coefficient in concrete beams, which were subjected to the effects of creep with linear coefficients from 0 to 3, ranged from 0.45 to 0.2 for positive bending moments and 0.3 to 0.2 for negative bending moments.

Em busca de uma nova inserção da América Latina na economia global

O objetivo deste artigo é discutir, de forma interdisciplinar, as condições necessárias e os caminhos para concretizar um modelo econômico e político de maior autonomia no cenário mundial para os países da América do Sul. O enfoque parte das condições políticas e sociais configuradas pela região ao fim da primeira década do presente século, enfatizando o papel do Brasil e considerando as relações econômicas e políticas do contexto internacional, a estabilidade política e o crescente protagonismo da China nos países da região. Analisa ainda aspectos referentes à importância da política social e da política de defesa comum sob a União das Nações Sul-Americanas (Unasul).