Numerical Simulation and Failure Analysis of St. Konstantinos Church, after the Kozani Earthquake

This paper focuses on the earthquake performance of St. Konstantinos church that was damaged during 1995 Kozani earthquake. The structural elements that suffered the most damage were the main longitudinal exterior masonry walls, which included a considerable number of door and window openings. Initially, a numerical study is performed to determine the stiffness properties of representative simple masonry wall arrangements that included combination of openings. Based on the findings of this preliminary study, a three-dimensional (3-D) numerical simulation of the St. Konstantinos church was built. An analysis of the seismic response was next performed where the masonry walls were represented by linear “beam type” frame elements. The recordings of the ground acceleration that were obtained during the earthquake at a close distance from the church were utilized. The deformation levels obtained from this 3-D seismic analysis are used next, to approximate the earthquake performance of masonry walls through a more refined two-dimensional (2-D) FEM representation. These linear simulation results are utilized to predict the development of flexural or shear limit-state conditions for the exterior masonry walls. It was verified that the observed damages are in agreement with such predictions. The 2-D numerical investigation was extended to include a non-linear simulation of the observed behaviour utilizing either a Mohr–Coulomb or a modified von Mises failure envelope. Again, the observed damage of the masonry wall was approximated reasonably well by these non-linear numerical predictions. A retrofitting scheme which included the construction of internal reinforced concrete jacketing was also briefly presented and its beneficial result in the structural performance was verified.