High Fidelity Numerical Seismic Modeling of Ancient Brick Structures

The evaluation of the seismic vulnerability of historical masonry buildings is a difficult task due to the uncertainty regarding structural characteristics and construction techniques, mechanical properties, and pre-existing damage. Hence, there is a need for an efficient computational technique for analyzing such structures and providing reliable results for a large number of buildings within a reasonable time frame. The present work describes the study of the seismic vulnerability using the applied element method (AEM) for high fidelity nonlinear structural analysis. The work is part of activities undertaken within the European Union funded project “INACHUS” (7th framework programme “Technological and Methodological Solutions for Integrated Wide Area Situation Awareness and Survivor Localization to Support Search and Rescue Teams”). Recently published studies highlighted the capability of AEM to overcome the limitations of the current structural analysis techniques, both in terms of results accuracy and in terms of use of computational resources. 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. 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 by subjecting the structure to multiple levels of seismic acceleration and evaluating the performance for each case. The study starts with a single building and then develops to studying multiple buildings at the same time. The objective is to detect extent of collapse for buildings, then road interruption and additional damage to the surrounding structures. A case study was performed by simulating and assessing a whole portion of the historic center of the city of Roquebillière, France. The study identified retrofitting actions, and demonstrated the practicality of using this technique to evaluate the accessibility of strategic roads for the purpose of reliable emergency planning.