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Civil-Comp Proceedings
ISSN 1759-3433 CCP: 79
PROCEEDINGS OF THE SEVENTH INTERNATIONAL CONFERENCE ON COMPUTATIONAL STRUCTURES TECHNOLOGY Edited by: B.H.V. Topping and C.A. Mota Soares
Paper 196
Non-Linear Homogenization of Quarry Masonry M. Šejnoha, V. Blazek, J. Zeman and J. Šejnoha
Department of Structural Mechanics, Faculty of Civil Engineering, Czech Technical University in Prague, Czech Republic Full Bibliographic Reference for this paper
, "Non-Linear Homogenization of Quarry Masonry", in B.H.V. Topping, C.A. Mota Soares, (Editors), "Proceedings of the Seventh International Conference on Computational Structures Technology", Civil-Comp Press, Stirlingshire, UK, Paper 196, 2004. doi:10.4203/ccp.79.196
Keywords: quarry masonry structures, first-order homogenization scheme, damage and plasticity models, damage-induced anisotropy.
Summary
The quarry masonry as a structural material has been extensively used
in the history, mainly due to wide availability of the material as
well as its good mechanical properties. Therefore, in the context of
repair and preservation of historical structures, a reliable and
realistic constitutive model of material behavior is needed for a
proper planning of necessary technological operations. In the past,
design and construction of these structures has been based on a
balanced combination of experience and trial-and-error methods, which
compensated for limited knowledge of material behavior.
Even nowadays, in spite of substantial progress in constitutive and numerical modeling, the engineering analysis of these structures builds upon a number of simplifying assumptions and phenomenological relations. This can be primarily attributed to the fact that quarry masonry is a heterogenous material with very complex structure consisting of phases that exhibit quasi-brittle behavior. In the last decade, techniques of numerical first-order homogenization have acquired an increasing attention in realistic modeling of regular masonry structures, both in the elastic [1] and inelastic range [5]. The most attractive features of the homogenization-based approach is that the non-linear behavior of the material, its initial anisotropy together with its evolution due to progressive failure, observed for real-world structures [3], directly follow from the analysis of a unit cell of a masonry structure [5] rather than from a particular format of the constitutive model. The present contribution addresses a specific application of these techniques to the homogenization of quarry masonry forming the filling of the Charles Bridge in Prague.
The first step of a successful implementation of the numerical
homogenization analysis is the definition of geometry of the periodic
unit cell that represents the morphology of a real material. In the
context of the present problem, the only morphology data available are
provided by in-situ observation. Based on the analysis of core and dug
holes, the volume fraction of arenaceous marl blocks, average joint
thickness and representative shapes of individual stone blocks were
estimated and used to construct an eight-stone periodic unit cell with
dimensions 0,64 m
The obtained response of the unit cell confirmed the ability of the
model to (at least qualitatively) represent the complex behavior of
irregular quarry masonry. For a loading dominated by the macroscopic
strains In summary, the proposed methodology appears to be able to obtain quantitatively correct behavior of the material. Moreover, the damage-induced anisotropy evolution, neglected in simplified engineering approaches, will be captured by the present numerical simulation. Once the missing material data for individual phases are provided by experiments, the effects of repair and strengthening operations on analyzed structure can be realistically assessed. References
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