Seismic analysis of masonry bridges by a nonlinear 3D FEM

In the present paper, a finite element methodology for the static and dynamic nonlinear analysis of concrete and large order historical masonry structures is described and applied to the seismic analysis of the historic Arta bridge, in western Greece, under 2D and 3D conditions. According to this methodology, the inelastic material behaviour is simulated with the aid of the theory of continuum damage mechanics. More specifically, the developed damage model is a combination of the theories of Mazars and Faria-Oliver and is characterized by its successful modeling of the mechanical behaviour when applied to concrete or masonry structures. In addition, the model permits an easy calculation of damage indices for various locations of a structure and a global (qualitative) damage index for the whole structure as well. The influence of the travelling wave effect is also examined under 2D and 3D conditions. It is observed that seismic excitations create damage (crack formations) at critical bridge areas and that the inelastic material modeling is crucial when a more realistic determination of the bridge response under static and especially dynamic loading conditions is required. A comparison between the cases of single and multiple support excitation (travelling wave effect) leads to the conclusion that the first case gives an overall response, which is characterized by the presence of damage in many more areas of the examined bridge.