**1. Introduction**

The earthquake, which has been occurred on 6 April 2009, has been a catastrophic event for both the city and the University of L'Aquila [1]. Nevertheless, the disaster have to be trans‐ formed in a tremendous opportunity to revitalize the area, with important benefit for the national and international scientific community to experience the effectiveness of new systems and technologies, and consequently to base, on these results, new developments in several different fields.

The present chapter aims to summarizes the observations made at L'Aquila regarding the dissemination of new technologies belonging to the structural control and health monitoring fields, immediately after the earthquake and in the reconstruction phase [2].

Two synthetic databases are presented and discussed regarding, respectively, the installed seismic protection systems and the structural monitoring experiences, available to the author personal knowledge, and probably mostly incomplete at this moment. Firstly, the large use of new seismic protection systems, using both base isolation and energy dissipation devices, in the new construction and in the retrofitting of existing structures, mainly made in reinforced concrete, is categorized and the main features of the installed systems are synthesized. Secondly, the efforts done in the area of structural monitoring, especially for strongly damaged monumental churches and building, are described and, based on the available information, the characteristics of the used instrumentation, either for permanent or not permanent installation, are classified.

Finally, the results acquired during the development of two different case studies, by a research group of the University of L'Aquila, are presented in detail.

© 2013 Gattulli; licensee InTech. This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2013 Gattulli; licensee InTech. This is a chapter distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2013 Gattulli; licensee InTech. This is a paper distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

In the first one, the use of energy dissipation devices, such as nonlinear fluid viscous dampers, in a peculiar configuration scheme that make use of the concept of dissipative interconnection in adjacent structures, is illustrated. Indeed during the seismic event of 6th April 2009, the edifices of the Engineering Faculty have suffered particularly for seismic induced large structural displacements and accelerations which have brought them out of order due, mainly, to the failure of non-structural elements [3,4], the breakage of wiring and piping systems and the destruction of furniture and machineries. In particular, among the three recently built buildings of the campus, erected in the early 90's, the so-called "Edifice A" presents the most critical damage scenario, which has been objective of a significant rehabilitating intervention. The critical choice during the design stage and testing are illustrated through several analysis conducted with the aim to construct reliable numerical models reproducing the experienced seismic behaviour and the expected enhancement due to the retrofitting. In particular, the main results of a dynamical testing campaign [5] used to calibrate a series of finite element models, able to reproduce the structural behaviour of the Edifice A, at low oscillation amplitude, are here discussed. Nonlinear static and dynamic structural analysis has been used in the evalu‐ ation of the structural performance [4] and of the proposed structural control effectiveness [6]. Device testing [7] and installation procedures have been considered in the overall process to reach high level of confidence in the matching of the rehabilitation goals with the realistically installed seismic protection system.

to the local equilibrium reached, before the earthquake, at any level (social, economical, etc). Indeed, the 27000 students attending the classes in the building of the several Faculties constitute a large revitalizing effect for the production realized in the territory of L'Aquila. In contrast the damage suffered by this extremely strategic institution for its territory through the scarce seismic performance of the entire property asset [1] has bad consequence in the reconstruction phase. Notwithstanding the large losses, many projects have been started, immediately after the earthquake, to react immediately to the catastrophic event. Due to a long period of aftershock swarm, still continuing in the area, the main idea, which it was followed, is the realization of safer structures with affordable costs. Therefore, several projects have been realized exploiting the use of passive control for seismic protection, either through the concept of base isolation or by enhancing the dissipation capacity of the structural system. These interventions have been conducted both for buildings devoted to public services and to residential buildings. The realizations using a base isolation system as main seismic protection strategy, available to the author knowledge, are summarized in Table 1 while the structural

Advanced Applications in the Field of Structural Control and Health Monitoring After the 2009 L'Aquila Earthquake

http://dx.doi.org/10.5772/55438

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Immediately after the earthquake one of the main problems, is to found the right compromise between temporary or definitive construction of houses, which can be used to maintain the population at the site. In the case of L'Aquila a peculiar solution to the problem has been provided directly by the National Government, the Project CASE, consisting in 185 buildings constructed in record time to provide a right accommodation to a large amount of the population through the realization of 4.500 apartments in 185 buildings [12]. Every building has the same structure at the ground floor (columns with seismic isolators and a rigid slab), while the superstructures have been made with different construction solutions and materials.

Among public buildings, the new venue of ANAS, the Italian Infrastructure Public Authority for the management of the road network, has been built in a very short time. It has a circular plant and a base isolation system. Furthermore, it was carried out the demolition and recon‐ struction of a portion of the Court Law Building, the construction of the new venue of the Faculty of Letters (with the process started in 2006) and the retrofitting of the Faculty of Engineering, project extensively discussed in the following section 4. As important as the public buildings, there were several retrofitting interventions in residential damaged build‐ ings. Among these, quite interesting it is the case of the condominium in via Rauco, being one of the first examples of a peculiar technology application for the uplift of the buildings. During the realization thanks to hydraulic jacks, it was possible to uplift the building of 60 cm and insert seismic isolators at ground floor level. Another example is the case of condominium Habitat, consisting in 10 buildings of different heights connected to one another by 9 bodies scale, arranged to make a semicircular plant all together. The intervention has been charac‐ terized by the realization of a single rigid slab to the level of the first deck and the cutting of the columns on the ground floor level, to allow insertion of the devices. In this way it was

possible to realize a unique isolation system for all the bodies of the condominium.

design characteristics.

The data collected regarding structural control systems, recently, realized in L'Aquila are summarized in Tables 1 and 2, in which is specified, for each construction, the type of inter‐ vention, the type and quantity of the devices used and, for some of them, the available specific

systems enhanced through dissipative devices are described in Table 2.

In the second one, the use of a wireless sensor network (WSN) for permanent structural health monitoring (SHM) of historic buildings in a seismic area is considered, evidencing the conducted specific activities to customize the system for the continuous assessment of the damaged conditions. On the basis of a defined design strategy [8-10], a permanent structural monitoring systems has been installed on the damaged *Basilica of S. Maria di Collemaggio*, at L'Aquila and it is currently working during the whole day. The main findings in the design, delivery, installation and management of the monitoring systems are presented. A series of tests has been conducted for the monitoring systems and the acquired data have been used for structural identification purpose on the basis of clearly stated procedure [11]. Several regis‐ trations acquired with the systems during local aftershock or more distant, relatively strong, shocks, as for example the recent Emilia earthquake (20-05-2012), are used to demonstrate the possibility given by the dynamic monitoring to produce valuable information for the structural assessment of historical monuments which can be in strongly damaged condition, such as the case of the Basilica.
