Seismic Behaviour of the Walls of the Parthenon A Numerical Study

Abstract

A numerical study of the behaviour of the walls of the Cella of Parthenon subjected to seismic loading is presented. Commonly used numerical codes for masonry structures based on continuum mechanics are unable to handle the behaviour of discontinuous walls of ancient monuments, in the same way as continuum models cannot capture the behaviour of drum-columns. In this analysis, the discrete element method was used, which has been proven, in previous research, capable to accurately predict the response of discontinuous structural systems. The marble structural stones of the walls were modeled as rigid blocks with frictional joints between them. Two types of models were used in the analyses: (i) a sub-assembly consisting of only a section of the wall of limited length, either as it is in-situ (partially collapsed) or with its full height (restored) and (ii) considering the whole structure partially restored. In one of the models of type (i), the existing damage of the stones was also implemented. Analyses were performed with and without considering the metallic elements (clamps and dowels) that connect adjacent stones. The numerical models represented in detail the actual construction of the monument. The assemblies considered were subjected to all three components of four seismic events recorded in Greece. Time domain analyses were performed in 3D, considering the non-linear behaviour at the joints. The general response profile was examined, as manifested by rocking and sliding of individual stones or groups of stones. The effect of several parameters was investigated including: the coefficient of friction at the joints, the imperfections of the blocks, the existence or not of connectors between adjacent blocks and the seismic motion characteristics. The results of the sub-assembly models and the full-structure model were compared in order to estimate the accuracy of the sub-structuring technique. The effect of the restoration of the wall to its original height was also examined. Conclusions were drawn based on the maximum displacements induced to the structure during the ground excitation and the residual deformation at the end of the seismic motion.