Intersectii / Intersections
Vol.4 No.4 Art.40
Contribution to non-linear constitutive modelling of masonry structures in 2D
by
Jirí Brožovský, Alois Materna, and Ivan Kološ
Abstract
This paper discusses a non-linear constitutive model for modelling
of masonry in 2D. The model consists from two independent parts:
the model for mortar and the model for bricks or stones.
The reason of using two different constitutive models is our need
to be able to modell individual bricks (or stones in the case of
a stone masonry) and the mortar between the bricks.
We have decided to use a smeared crack approach for the modelling
fo a mortar. It is an approach that is widely and successfully
used for a constitutive modelling of concrete and we assume that
it can be also applied to a mortar that is very similar to a concrete.
The model of mortar is based on an equivalent one-dimensional
stress-strain relation that depends also on 2D state of stress
(through the Kupfer's failure criteria that is used to obtain
the limit stresses for the one-dimensional stress-strain relation)
and on some special material properties such is fracture energy of mortar.
Bricks are modelled in a different way, As a generally brittle,
they often can't be effectively modelly by the smeared crack
approach. The damage of the brick (a crack) usually goes through
the whole brick and it can be assumed that its occurrence depends
on a stress intenzity on an area and not on the stress size in
an individual material point. Thus we have decided to use a
simple approach that can be describes as a very basic non-local material model.
After the ckack on the brick is detected the material properties
are changed in a moment. Unlike the model for a mortar, it is
assumed that there is no unloading curve for this model.
KEYWORDS: finite element method, constitutive modelling, masonry, mortar, bricks, crack band model, smeared cracks.
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