![]() |
Computational & Technology Resources
an online resource for computational,
engineering & technology publications |
Civil-Comp Proceedings
ISSN 1759-3433 CCP: 81
PROCEEDINGS OF THE TENTH INTERNATIONAL CONFERENCE ON CIVIL, STRUCTURAL AND ENVIRONMENTAL ENGINEERING COMPUTING Edited by: B.H.V. Topping
Paper 189
Analysis of Historical Masonry Structures using Three Dimensional Solid Elements C.A. Syrmakezis, A.K. Antonopoulos and O.A. Mavruli
Institute of Structural Analysis and Aseismic Research, School of Civil Engineering, National Technical University of Athens, Greece Full Bibliographic Reference for this paper
C.A. Syrmakezis, A.K. Antonopoulos, O.A. Mavruli, "Analysis of Historical Masonry Structures using Three Dimensional Solid Elements", in B.H.V. Topping, (Editor), "Proceedings of the Tenth International Conference on Civil, Structural and Environmental Engineering Computing", Civil-Comp Press, Stirlingshire, UK, Paper 189, 2005. doi:10.4203/ccp.81.189
Keywords: 3D finite elements, solid finite elements, masonry structures, stress analysis, failure analysis.
Summary
The implementation of three-dimensional solid finite elements when performing finite
element analysis of historical structures and monuments is discussed. For this
category of structures, consisting usually of masonry systems, high standard
requirements, contradict modeling assumptions that lead to simplifications implied
by the use of shell elements. To overcome lost accuracy, the use of solid elements is
proposed.
The same necessity also appears especially when abrupt changes in the building shape occur, for example at the areas of roof-wall intersections, openings, vaults, domes etc. As a result of these geometrical peculiarities, area dimensions of finite elements are necessarily small due to the proper meshing requirements and their thickness, which usually represents the width of the wall, even greater than their other two dimensions. In this case the use of three-dimensional solid elements is imposed in order to overcome lost accuracy. The solid finite elements used in this paper are an eight-node hexahedron brick and a six-node pentahedron wedge. They are isotropic and they have three translational degrees of freedom for each node. Global Cartesian coordinates are expressed on the basis of local coordinates, by linear polynomial shape functions. They are considered to be isoparametric. The Jacobian matrix and stiffness matrix are evaluated as in [1,4]. The efficiency of the method is demonstrated through application to a Byzantine monastery, situated in Athens. Its support system consists mainly of regular shape stone masonry. Wall width variations, niches, openings and other particular geometrical configurations reveal the efficiency of three-dimensional solid finite elements in simulating the structure in the most realistic way that looks like the physical system.
In the case of three-dimensional elasticity consideration, three principal stresses
are produced, each one corresponding to the relevant principal axis. In order to adapt
the problem of determination of mechanical failure to considerations made for
two-dimensional assumptions, the influence of the third occurring principal stress over
the other two remaining principal stresses has to be evaluated. The proposed process
is repeated three times. Each time, a principal stress In order to perform failure analysis the establishment of a failure criterion is crucial. For two-dimensional assumptions, a modified Von Mises criterion, adapted especially for masonry structures, is presented. Failure occurs when a biaxial stress state of a node is represented by a point outside the surface area described in [3]. Failure analysis takes place using "FAILURE", a software program developed by the author's research team (NTUA, Greece), [5]. Graphical outputs including failed areas are produced, for each plane.
The methodology proposed is applied to the structure considered, which is
subjected to horizontal seismic loading, according to [2]. Elimination of one
principal stress at a time, and subsequent modifications of remaining principal
stresses applied to the solid nodes, permit reduction of the three-dimensional state to
biaxial. Two-dimensional data are elaborated considering, in turn, all three sets of
stresses,
References
purchase the full-text of this paper (price £20)
go to the previous paper |
|