Filippo Casarin

Seismic Assessment of Complex Historical Buildings: Application to Reggio Emilia Cathedral, Italy

The definition of structural safety of a historical masonry structure is still a concept that is somewhat difficult to interpret. Whereas for new masonry structures, it is possible to have useful indications about their structural behavior, as the analysis turns to “historical” constructions such a task became increasingly more difficult. Furthermore, the needs of preservation of the historical, cultural, and architectural essence of the building in many cases contrast with the needs of providing the “adequate” capacity to its structure, especially in order to withstand the design seismic loads. The study presented in the article is related to the definition of a knowledge and safety assessment path , concerning masonry religious buildings with a monumental character. A complex building, the Santa Maria Assunta (Our Lady of the Assumption) Cathedral in Reggio Emilia (Italy), is studied in order to evaluate its structural behavior thus defining its seismic vulnerability, by using different investigation and analysis methodologies.

Structural Aspects of The Conservation of Historic Masonry Constructions in Seismic Areas: Remedial Measures and Emergency Actions

Preservation of historic buildings is a demanding task, especially in seismic zones, where vulnerable constructions can suffer severe damages and losses. The last earthquake that struck the Abruzzo region in Italy in 2009 caused a particularly extensive damage. Lessons learned by previous experiences and the knowledge acquired through researches allowed facing the first emergency period involving universities, civil protection, and the Cultural Heritage Ministry. The result of this collaboration was the survey and the realization of emergency interventions for thousands of buildings in few months after the earthquake, waiting for the definition and design of definitive solutions.

L'Aquila 6th April 2009 Earthquake: Emergency and Post-emergency Activities on Cultural Heritage Buildings

The earthquake that struck the Abruzzo region on 6th April 2009 at 3:32 a.m., had its epicentre in the capital of the region, L’Aquila, and seriously affected a wide area around the city, where many historic towns and villages are found. Due to the strategic importance of L’Aquila, a strong and organized civil protection action was necessary to face the emergency. In addition, the structural damage on historic buildings and centres was enormous. Therefore, it was necessary to carry out specific actions aimed at the safeguard of this heritage. These can be shortly listed as: set up of the organizational and decisional structure, damage surveys, temporary interventions to provide the minimum safety conditions, set up of a monitoring plan for some important monuments, set up of a methodology to intervene on complex and connected buildings in the historic centres, definition of adequate materials and techniques to intervene on the damaged buildings.

Shaking Table Tests on Multi-Leaf Stone Masonry Structures: Analysis of Stiffness Decay

The influence of the natural hydraulic lime-based grout on the dynamic behaviour of injected multi-leaf stone masonry elements is discussed in the paper. Shaking table experiments on two stone masonry buildings, tested before and after grout injection, have been performed. The paper focuses on the analysis of both the recorded accelerations and related displacements, at the bottom and at each further storey. This leads to evaluate the stiffness of the unstrengthened and injected structures. The input at increasing PGA allowed the stiffness decay to be studied, simulating a gradual damaging of the structures. These results were also interpreted in the light of both computed frequencies and mode shapes. Finally, the comparison among these results, obtained from all the models, allows to deepen the knowledge concerning the effects induced by the lime-based grout injection and on its capability to modify the dynamic behaviour, when intervening on a damaged (repairing) or on an undamaged (strengthening) structure.

An Automatic Algorithm for the Execution and Elaboration of Sonic Pulse Velocity Tests in Direct and Tomographic Arrangements

The use of non-destructive tests (NDT) in the investigation phase of existing constructions plays a relevant role for the quick evaluation of the masonry quality during the survey phase and for the extension of results obtained from more punctual minor-destructive (MDT) or destructive tests (DT).

The Bahrain Pearling Path: Urban Planning, Structural Investigation and Design of the Strengthening Interventions

The Bahrain Pearling Path (or Pearling Testimony) is a cultural heritage site inscribed on the UNESCO World Heritage List in 2012. The site consists of seventeen buildings in Muharraq City, three offshore oyster beds, part of the seashore and the Qal’at Bu Mahir fortress on the southern tip of Muharraq Island, from where boats used to set off for the oyster beds. The listed buildings include residences of wealthy merchants, shops, storehouses and a mosque. The site is the last remaining complete example of the cultural tradition of pearling and the wealth it generated at a time when the trade dominated the Gulf economy (2nd century to the 1930s, when Japan developed cultured pearls). In the framework of the restoration activities undertaken by the Bahrain Authority for Culture and Antiquities (BACA), an effort is currently ongoing for the re-use of the existing buildings preserving their structural behavior, also according to the ICOMOS ISCARSAH restoration principles. An extensive investigation campaign, preparatory for the successive strengthening interventions, was then carried out in 2017, aiming at defining the main mechanical features and characteristics of the stone masonry walls (composed by the locally named “coral stone”) and of the timber floors, originally (and still today) composed by round mangrove logs. The paper refers on the investigation campaign outcomes and the subsequent design criteria for an effective, however respectful, strengthening intervention.

Mechanical Characterization of Masonry Typologies in Israel via Flat Jack Tests

During the last decade, the Laboratory of the Department of Civil, Architectural, and Environmental Engineering department at the University of Padova, together with a Spin-Off of the same University, Expin srl, and the consultant engineering company Schaffer & Ronen ltd., carried out more than fifty on site single and double flat jacks on masonry panels of a relevant sample of existing masonry buildings in different historical sites in Israel. Typical Israeli masonry used in historical buildings consists of limestone, calcar (sand) stone, and Basalt stone masonry, with mostly lime based mortar as a binder. Double flat jack tests were employed on two main types of stone walls: single-faced and two-faced stone wall (the most common stone masonry arrangement). From these tests it was possible to obtain the characterization of the mechanical properties of the stone masonry panels tested, belonging to different construction eras and masonry types. Double flat jack tests were mainly carried out following the local state of stress determination via single flat jack. The paper presents the results with a classification of the masonry types mechanical characteristics. This ongoing work, to be complemented with laboratory tests in future stages, may represent a preparatory work for the development of reference characteristic values of the different masonry types of the country, to be included in Israeli technical standards.

Evaluation Of The Structural Behaviour OfHistoric Masonry Buildings By A Sonic PulseVelocity Method

Sonic pulse velocity tests are mainly used in historic masonry structures for consistent diagnosis evaluations and checking of the effectiveness of strengthening interventions. In this paper, results obtained from sonic tests applied on two historical constructions, namely the cathedral of Reggio Emilia and the bell-tower of the S. Zeno basilica in Verona, Italy are presented, to allow structural models being calibrated on an experimental basis for the definition of the behaviour of the buildings. The sonic investigation method is preliminarily discussed in the light of the outcomes of an EU research comprehensive project, also aimed at the identification of capability and limits in applications in the historical heritage field. masonry structures, FE modelling, sonic pulse velocity test.

Investigation Methodology Applied to the Structure of the Church of St. Biagio in L’Aquila

After the earthquake that stroke the city of L’Aquila during the night of April 6th 2009, many historical buildings at the city centre were severly damaged. Nevertheless many others survived the seismic event with only local damages, showing a good mechanical behaviour against vertical and horizontal actions. In order to continue preserving these buildings, a careful investigation is necessary before applying any repair technique, new or traditional to understand the past design practices for building durable and safe structures. In order to understand the structural behaviour of the church of St. Biagio in L’aquila, an extensive diagnostic investigation based on non-destructive and minor destructive techniques was carried out by the authors. The paper describes mainly the applied methodology which can produce some guidelines to be followed in the future study of other Cultural Heritage (C. H.) buildings hit by the earthquake.

Settlement Induced Damage Modelling of Historical Buildings: The Bell Tower of the “Basilica dei Frari” in Venice

The paper presents the case study of the “Basilica dei Frari” in Venice for which a non linear numerical analysis has been recently performed in order to assess its structural conditions. In fact, from the end of its construction, in the XIV century, the building suffered from structural deteriorations mainly due to settlements affecting the bell-tower. A main structural intervention was carried out at the beginning of the XX century, aimed at stopping the outward tilting process of the tower. The intervention was so effective that it induced an opposite effect on the tower, which started to rotate towards the cathedral. Several studies were carried out since then to evaluate the interaction between tower and church, including in recent years structural monitoring and numerical modelling, besides a strengthening intervention consisting in soil micro-fracturing. A non linear numerical model of the church-tower complex was implemented and compared to the outcomes of the available experimental data (monitoring, investigations), also considering the historical process leading to the present day conditions. To gain reliable settlement damage predictions it was necessary to adopt tensile-softening crack models in the numerical studies and perform non linear analyses able to trace the complete response of the structure. The aim of the modeling was also, besides the assessment of the structural conditions of the complex, to predict the structural effects of the physical “separation” between tower and cathedral.