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Analysis of the global second-order effects on irregular reinforced concrete structures using the natural period of vibration
| IBRACON Structures and Materials Journal
Analysis of the global second-order effects on irregular reinforced concrete structures using the natural period of vibration
Fábio Fleming Leitão
Universidade Estadual de Campinas - UNICAMP
Gustavo Henrique Siqueira
Universidade Estadual de Campinas - UNICAMP
Luiz Carlos Marcos Vieira Jr.
Universidade Estadual de Campinas - UNICAMP
Saulo José de Castro Almeida
Universidade Estadual de Campinas - UNICAMP
Abstract
The parameter, a simplified method recently presented, allows to estimate the global second-order effects on reinforced concrete frames using the natural period of vibration. This parameter was developed based on the fact that both natural period of vibration and global second-order effects depend essentially on the stiffness and mass matrices of the structure, being thus related. In this paper, numerical analyses are conducted on nine models with different patterns of irregularity in terms of geometry in plan and stiffness. The main purpose of these analyses is to evaluate the applicability of the parameter in asymmetric structures as well as that can present torsional modes as the fundamental mode of vibration. In addition, different hypotheses are tested in order to verify the influence of the different modes of vibration in the structural sensitivity to global second-order effects. Results of the simplified analyses were compared to the final bending moment values obtained through a nonlinear numerical analysis considering the P- effect. It is observed that the parameter is a promising indicator for a simplified estimation of the global second-order effects for concrete frames, especially when higher modes of vibration are taken account in the analysis.
Author Biographies
Fábio Fleming Leitão, Universidade Estadual de Campinas - UNICAMP
Departamento de Estruturas
Gustavo Henrique Siqueira, Universidade Estadual de Campinas - UNICAMP
Departamento de Estruturas
Luiz Carlos Marcos Vieira Jr., Universidade Estadual de Campinas - UNICAMP
Departamento de Estruturas
Saulo José de Castro Almeida, Universidade Estadual de Campinas - UNICAMP