SEISMIC VULNERABILITY ASSESSMENT OF THE HISTORICAL BUILDINGS IN ITALY USING AEM

In recent years, Italy was hit by several significant seismic events, causing numerous human losses and thousands of injuries. These events are concentrated along the Apennines mountain chain, where many small and ancient historical cities are located. Earthquakes caused extensive and severe damage to the territory’s valuable real estate heritage including eminent churches, important palaces, a variety of monumental buildings and structures. The evaluation of the seismic vulnerability of such buildings is a difficult task and presents significantly higher level of complexity if compared to the case of new structures. This is due to the inherent uncertainty characterizing ancient buildings, regarding structural characteristics and construction techniques, mechanical properties of the heterogeneous material like the masonry, and pre-existing damage due to past actions. Hence, there is a need for an efficient computational technique for analyzing such structures and providing reliable results so that the governments can intervene and optimize the use of available economic resources. The present work describes the study of the seismic vulnerability of a typical historical building representative of construction in the southern European countries using the Applied Element Method (AEM) for high fidelity nonlinear structural analysis. The work makes use of some findings obtained within the European Union funded project “INACHUS” (7th framework programme “Technological and Methodological Solutions for Integrated Wide Area Situation Awareness and Survivor Localisation to Support Search and Rescue Teams”). In AEM, the structure is discretized through an assemblage of relatively small elements connected by a set of non-linear springs located at contact points distributed along the element faces. Normal and shear springs transfer the normal and shear stresses between the elements. Through the springs it is possible to represent the non-linear material behavior, the element separation or contact, and eventual collision. The paper reports the results of the seismic simulations, analyzing the effects of the implementation of different structural details, such as presence of arches and vaults and interaction between structural elements with different types of connections that have a significant effect on the behavior of such historical buildings. The modelling of these details requires prohibitively expensive computational resources in the common modelling techniques based on FEM, due to the significant increase of the number of elements and the need to maintain the nodes compatibility. Moreover, in many cases, historical buildings suffered significant damages due to detachments between different structural parts even with low seismic acceleration. The paper demonstrates the application of the AEM method implemented in the software Extreme Loading for Structures (ELS) for performance based design of these kinds of historical structures.