FINITE ELEMENT MODELLING OF PLANE FRAME SUBJECTED TO RANDOM WIND EXCITATION WITH DYNAMIC ELASTOPLASTIC BEHAVIOR

Resumo

This work presents a finite element approach of dynamic elastoplastic analysis in plane
frame subjected to random excitation caused by wind action. The wind random velocity is modelled
mathematically by using Power Spectra Density Method in combination with Shinozuka’s model, with
commonly employed wind spectra, such as von Kármán, Davenport, Kaimal and Harris. From these
spectra, the dynamic wind loading is determined from the sum of the mean and floating wind
velocities. Thus, it is possible to obtain the wind loading vector that is applied in the structure dynamic
governing equation. The governing equation is formulated by Euler-Bernoulli beam theory, and it is
discretized by using a conventional Lagrange – Hermite element. The time stepping process is carry
out by HHT algorithm, and the material nonlinearity is modelled by von Mises isotropic hardening
model. Finally, several applications are presented, where different wind spectra are employed to
determine mechanical parameters of structure responses, such as stress, strain, displacement, among
the other. The error norm L2 of displacement is determined for different finite element discretization
refine, which aims to analyze the effects of space discretization in this type of analysis. Also, the
relative differences are determined with the purpose to compare the different mechanical behavior of
structure when subjected to different wind spectra.