Experimental Detection of Damage Evolution in Concrete under Multiaxial Compression: Fid-Bau Portal

Experimental Detection of Damage Evolution in Concrete under Multiaxial Compression

Petkovski, Mihail

Abstract

The nonlinear inelastic stress-strain relationship of concrete is a result of changes to the fabric of the material caused by several damage mechanisms. Existing experimental research on concrete provides very little information on the evolution of these mechanisms. Instead, most experimental studies are limited to measuring the external loads and deformations of concrete specimens. The aim of the research presented here is to provide a direct link between macroscopically observed global stress-strain behavior and the development of damage mechanisms within the specimens. A novel experimental procedure is introduced to monitor the changes in the material during a conventional multiaxial compression test. This procedure, comprising small stress probes repeated at selected points of the stress-strain history, is designed to provide data on the tangent stiffness operator and the associated acoustic tensors. The acoustic tensor with the minimum value of its determinant provides information on both magnitude and orientation of the damage. The stress-probing methodology and some of the key practical aspects and limitations of the experimental procedure are illustrated by using five multiaxial compression tests as examples of different stress-strain histories. The results of the test methodology presented in this paper give an indication of the extent of damage and accurate information about its orientation. This paper therefore shows that the stress-probing procedure can be incorporated in multiaxial tests designed to monitor the relationship between damage evolution in the material and macroscopically observed stress-strain response of the specimen.