US EPA

6873882 

Journal Article 

Brittle solid under compression .1. The problem of macro to micro linkage 

Blechman, I; , 

1997 

Yes 

International Journal of Solids and Structures
ISSN: 0020-7683 

PERGAMON-ELSEVIER SCIENCE LTD 

OXFORD 

2583-2594 

WOS:A1997XG59000004 

The macrodescription of the nonlinear behavior of a heterogen under compression, as given by the central function: sigma = epsilon EG, employs the Gaussian term G, which expresses the stochastic character of the heterogen's atrophy through microcracking and comprises two critical parameters: the limiting strain of elasticity (atrophy threshold)-epsilon(a), and the scattering factor-d. It does not, however, involve parameters of the microcracking mechanisms. As for the models of local lateral tension and microrupture, they are based on the gradients in Poisson's ratio and elastic moduli of the heterogen's components and are not related to the parameters of the heterogen in macro.Linkage of the micro and macro models was effected by generalization of the gradient micromechanisms. It showed that the strength of a brittle solid in compression is a function of its resistance to microrupture and of the gradient factor. Despite the fact that longitudinal compression creates the gradient strains, it is shown that the two critical macroparameters, epsilon(a) and d, are affected (in a probabilistic way) by two critical lateral strains : the minimal limiting strain of microrupture-epsilon(a)(R). and the strain of the mode (the maximum) of the pdf of the heterogen's resistance to microrupture-epsilon(M)(R).To check the obtained models, the linkage between the strength of concrete in tension. and compression was analyzed. It was found that their ratio reflects the gradient factor in the heterogen. The decrease in Poisson gradient with increasing strength can explain the faster increase in the compressive strength versus the tensile one. The obtained results confirm an old idea that the properties of a heterogen in tension represent its fundamental characteristics.In the light of the obtained models the failure of concrete in the Brazilian test seems not to be another type of tensile failure, but a distinct kind of degeneration of the heterogen due to gradient lateral strains induced through the strips under compression. (C) 1997 Elsevier Science Ltd.