Implementation of a damage model in a finite element program for computation of structures under dynamic loading

Nasserdine Oudni,Youcef Bouafia

doi:10.3221/igf-esis.35.32

Abstract

This work is a numerical simulation of nonlinear problems of the damage process and fracture of quasi-brittle materials especially concrete. In this study, we model the macroscopic behavior of concrete material, taking into account the phenomenon of damage. J. Mazars model whose principle is based on damage mechanics has been implemented in a finite element program written Fortran 90, it takes into account the dissymmetry of concrete behavior in tension and in compression, this model takes into account the cracking tensile and rupture in compression. It is a model that is commonly used for static and pseudo-static systems, but in this work, it was used in the dynamic case.

Highlights

The numerical program is employed in analyzing Koyna gravity dam and comparing the results with available results of many researchers find in literature
The earthquake records are in the form of accelerograms with horizontal and vertical components which are used as dynamic loads
W e note that the displacements are relatively low during the first two seconds because of low the amplitudes of the excitations. The displacements reach their maximum at 3.7 s and 7.5 s, 30 mm was recorded at 3.8 s, the maximum displacement value does not correspond to the maximum amplitude of the excitement that is recorded at 3.65 s

Summary

INTRODUCTION

The numerical program is employed in analyzing Koyna gravity dam and comparing the results with available results of many researchers find in literature. Mazars model [5] whose principle is based on damage mechanics which is a theory describing the progressive reduction of the mechanical properties of a material due to initiation, growth and coalescence of microscopic cracks. These internal changes lead to the degradation of mechanical properties of the material. E0 and 0 are the Young's modulus and the Poisson's ratio of the undamaged material; εij and σij are the strain and stress components, and δij is the Kronecker symbol. C 0 ijkl is the stiffness of the undamaged material This energy is assumed to be the state potential. Since the dissipation of energy ought to be positive or zero, the damage rate is constrained to the same inequality because the damage energy release rate is always positive

DAMAGE EVOLUTION

DYNAMIC EQUATIONS OF MOTION

RESULTS

CONCLUSION