Collemaggio Basilica Research Articles

Hypothesis on the Decrement of the First Natural Frequencies of the Santa Maria Di Collemaggio Basilica from Three Years Monitoring: The Role of the CLT Roof

ABSTRACT The long term dynamic monitoring of the Santa Maria di Collemaggio basilica revealed an unexpected trend of the first natural frequencies decreasing from their initial values estimated in 2018. The decrement of the natural frequency could originate from several factors. The structural system derives from the arrangement of four building materials: masonry (predominant), reinforced concrete (RC), timber and steel. Masonry is unlikely to suffer rapid decaying of their mechanical properties. Reinforced concrete (RC) and the embedded steel should not present decaying phenomena in the first years after built. Like- wise, the steel plates which connect the Cross-Laminated Timber (CLT) panels should not manifest a significant progression of corrosion in an indoor environment. Conversely, timber’s physical and mechanical properties, such as swelling and shrinkage, density, modulus of elasticity, strength have a time-dependent response, even in the long-term. Likely, the decaying of the natural frequencies depends on the CLT roof’s time-dependent be- haviour due to the potential modification of its mechanical properties and boundary conditions (interaction with the steel plates, e.g.). This paper presents selected results from the basilica’s three-years continuous dynamic monitoring and discusses an elementary mechanical model representative of the dynamics transverse to the nave walls. The mechanical model described by a limited set of parameters drives the assessment of the CLT roof’s possible role in causing the detected decrement of the natural frequencies.

Smart Architectural and Urban Heritage: An Applied Reflection

The aim of this paper is to present the use of 3D models and augmented reality (AR) to study and communicate architectural and urban values and, therefore, favor the development of dedicated forms of “smart heritage”. The study rises from a reflection on the concept of “heritage”, as defined in the international documents, intended as an evolving idea that puts together tangible and intangible aspects. Moreover, digital technologies favor “phygital” applications where the digital dimension support the traditional ones. In this way, AR allows the superimposition of multimedia information to heritage, respecting the historical matter of the artefacts, and supporting a “smart heritage” application. In particular, mobile AR, with real-time and ubiquitous visualizations, offers the opportunity to show past urban and architectural configurations to investigate and describe the transformations that have led to the current configuration, and consequently highlighting the present historical and architectural values of the buildings. Two case studies are presented: the square of St. Basilio Monastery, with its historical transformations, and the Basilica of Collemaggio, a pivotal building in the rites of “Perdonanza Celestiniana”.

Two-years static and dynamic monitoring of the Santa Maria di Collemaggio basilica

The Santa Maria di Collemaggio basilica is a 13th-century masonry masterpiece. The restoration works following the 2009 earthquake in L’Aquila included the installation of a permanent monitoring system. Crack gauges monitor a few significant cracks that appeared during the 2009 earthquake. Force-Balance accelerometers record the dynamic response of the entire structure. The dynamic response to ambient excitation leads to the estimation of the modal parameters. The current paper reports the outcomes of two years of static and dynamic monitoring from 1/1/2018 to 31/12/2019. The authors correlated the outdoor temperature and relative humidity to both the amplitude of the cracks and the modal parameters. The temperature deeply affects the static and dynamic response of the basilica. However, the linear correlations between the temperature and the structural response are diverse. There are cracks which stretch when the temperature rises and cracks which act oppositely. Natural frequencies lower when the temperature rises, while the same modes exhibit modal interaction phenomena.Furthermore, the natural frequencies of the basilica are not stationary but are moderately declining across the years. The basilica is a complex structure, where the different constitutive behaviour of three different materials, masonry, steel and timber may yield a varied structural response. The authors attempt to provide a qualitative interpretation of the observed behaviour, namely the detected correlations to the outdoor temperature, the lowering of the natural frequencies across the years and mode interaction phenomena.

The Recorded Seismic Response of the Santa Maria Di Collemaggio Basilica to Low-intensity Earthquakes

ABSTRACT The seismic response of masonry monumental structures is a debated matter. In this paper, the authors compare the dynamic response of the Santa Maria di Collemaggio basilica under low-intensity earthquakes to the dynamic response under operational conditions. A permanent number of accelerometers records the dynamics of the Santa Maria di Collemaggio basilica under both operational and seismic excitation. It is questioned whether the earthquake intensity and the ambient parameters affect the modal parameters. The Least-Squares Complex Exponential (LSCE) method leads to the FRF function estimation. The stable frequencies identify the linear modal parameters which are likely to reproduce the seismic response. The authors endeavour to discuss whether the detected variations of the modal parameters are due to possible structural or material non-linearities. A time-frequency analysis confirms the results of the linear identification method. Further, the estimate of the dynamic amplification factors gives a glance over the global response by evidencing the possible existence of a macro-element response pattern.

Assessment of structural interventions using Bayesian updating and subspace-based fault detection methods: the case study of S. Maria di Collemaggio basilica, L’Aquila, Italy

The article focuses on the assessment of a structural intervention using a simple Bayesian approach driven by subspace-based indicators. A permanent monitoring system installed in a monumental masonry structure, the basilica of Santa Maria di Collemaggio in L’Aquila Italy, continuously acquires vibration data. The results of modal identification are first reported and discussed. Then, the article delivers a damage detection procedure, tested on two sets of data measured by the façade accelerometers before and after the CLT (Cross-Lam Timber) roof connection, which are interpreted as damage and reference states, respectively. The application of Bayesian inference to a set of damage indicators for the assessment of the façade structural modification is presented and compared with the results of a non-parametric -tests. A computation procedure for the built of a statistical reference model is proposed by discussing the issue of the choice of the reference data set.

Dynamic identification of a masonry façade from seismic response data based on an elementary Ordinary Least Squares approach

A low magnitude seismic response of a historical masonry structure, the Santa Maria di Collemaggio basilica, was acquired by a complex monitoring system. Ten FBA accelerometers, nine placed on the basilica facade and one on the ground level, recorded respectively the base accelerogram (Input) and the structural response (Output).By means of an elementary form of dynamic identification, based on an Ordinary Least Square operator (OLS), it has been attempted to identify the dynamic properties of the facade during the seismic event. The results, in terms of mode shapes, natural frequencies and damping factors, identified by the proposed Input-Output method, are compared with the ones identified under operational conditions.Despite the low intensity earthquake, the assumed linearity of the response has been investigated from further analysis on the acquired data.

Numerical approaches for cross-laminated timber roof structure optimization in seismic retrofitting of a historical masonry church

In recent earthquakes, historical masonry churches have demonstrated to be vulnerable structures. Strengthening interventions based on the introduction of a roof diaphragm can be considered a valid solution in order to obtain a box-behaviour of this kind of structures. Among the possible different roof-diaphragm solutions, the wooden based ones represent an effective alternative, satisfying the conservation requirements in terms of material compatibility and reversibility, together with a significant improvement of the structural behaviour. After a short literature review of all the wooden based strengthening interventions, the possibility to consider cross-laminated timber (CLT) as a roof-diaphragm strengthening for existing churches is discussed in this paper. The effectiveness of this retrofitting solution is inquired numerically by means of different kind of linear and nonlinear analysis, focusing on the role played by the steel connections among the different CLT panels. The Basilica of Collemaggio has been chosen as case study to test the possibility to apply CLT roof diaphragm on an existing masonry church, adopting different modelling approaches. A short discussion on the optimisation of the steel connection layout is also presented.

THE INTEGRATION OF A SCAN-TO-HBIM PROCESS IN BIM APPLICATION: THE DEVELOPMENT OF AN ADD-IN TO GUIDE USERS IN AUTODESK REVIT

Abstract. In recent years, the generative process of building information modeling (BIM) digital models oriented to the digitisation of heritage buildings has been supported by the development of new modeling tools, able to integrate the point cloud data produced by laser scanning and digital photogrammetry in major modeling software applications such as Autodesk Revit and Graphisoft Archicad. Architectural and structural elements of churches, castles, and historical monuments such as complex vaults, arches, decorations and ornaments, irregular walls with a variable section and wall stratigraphy require higher levels of detail (LOD) and information (LOI) than new buildings. Consequently, the structure of a BIM model oriented to represent heritage buildings (HBIM) required the definition of a new digital process capable of converting the traditional techniques to the generation of 'unique' digital models able to connect different type of information. Consequently, the generation of 'new' 3D objects able to follow the constructive logic of the detected artefact has required the establishment of new grades of generation (GOG) and accuracy (GOA) to reduce the time and cost of the scan-to-BIM process. The main challenge of this research was the integration of these new modeling requirements in BIM software through the development of an add-in for one of the most used BIM software (Autodesk Revit). Through the generation of the complex vaulted system of the Basilica of Collemaggio (L’Aquila, Italy) and one of the most famous monuments of northern Italy (Arch of Peace in Milan, Italy), the following research shows how it was possible to support users in the HBIM generation, reducing the modeling impact of complex shapes from point cloud data and increasing information sharing for different BIM-based analysis, disciplines and users.

Generative HBIM modelling to embody complexity (LOD, LOG, LOA, LOI): surveying, preservation, site intervention—the Basilica di Collemaggio (L’Aquila)

In December 2012, EniServizi (the Italian multinational energy company), after the Earthquake that occurred at L’Aquila in April 2009, decided to undertake the project “Re-start from Collemaggio”, funding around 14 million Euro to restore the Basilica di Collemaggio. EniServizi, aware of the BIM potential role in the complex building and infrastructure domain in the world, required an advanced HBIM based on laser scanner and photogrammetric surveying to address decision-making processes among the different actors involved in the preservation process. The Basilica of Collemaggio has been re-opened to the public on December 2017. This paper tries to make a synthesis of the different lessons learnt, in relation to both positive and critical aspects relating HBIM feasibility, sustainability and usefulness to the challenging restoration and preservation field. The theoretical and practical HBIM approach here tackled overcomes the current BIM logic based on the sequential process adopted by the AIA and NBS Level of Development (LOD), characterized by a simple-to-complex-detailing process, working in the new construction domain and generally following the conceptualizing phase, the preliminary design, the executive design, the construction phase till to the facility management. A complex-mixed LOD approach, able to entail the richness, unicity and multiplicity of each component and to get the maximum degree of knowledge, has been experimented in order to derive informed decisions in terms of preservation, restoration and management since the starting phases of the architectural design. To this aim, a Level of Geometry (LOG) coherent to the Level of Accuracy gained by the high-resolution surveys has been adapted to the specificity of the restoration process of a historic monument and is here proposed through different Grade of Generation (GOG) protocols developed in the object modelling to support the preliminary and definitive design proposal of the conservation plan of the Basilica. Particularly, a NURBS-based parametric generative modelling process (GOG9-10) is here proposed in order to get models “BIM abled” to describe the complex geometry and to match the related information. Specific Level of Information (LOI) has been introduced to support the preservation process, to document the as-built and the management of the building after the intervention, moving HBIM toward multi-actor domain. Given the effort required by such approach, obtaining a cost-effective HBIM modelling embodying the complexity of each damaged element as acquired by the surveys (i.e. walls, pillars, vaults, beams) represents a challenging issue. The result of the overall process aims to contribute in lowering the initial HBIM modelling costs by deploying a sustainable complexity delivering protocols and specification and by boosting at the same time an interoperable cooperative HBIM habit among multi-actors across all the phases, spreading its usability after the restoration process. On the lesson learnt, the process of updating the current Codification criteria (UNI11337-2009) has been started with a draft proposal stimulating the debate for the future of HBIM adoption in the case of restoration, preservation and maintenance (UNI11337-2017): in the conviction that transferring the HBIM richness into the Life Cycle Management process will allow multi-actors to take in account the knowledge and information gained during the restoration, integrating the as-built updating and keeping updated the monument monitoring during the time being.

2D site response analysis of a cultural heritage: the case study of the site of Santa Maria di Collemaggio Basilica (L’Aquila, Italy)

The Santa Maria di Collemaggio Basilica is an important cultural heritage site and exemplifies Romanesque-Gothic art in the Abruzzo region (central Italy). Erected in the second half of the XII century, the Basilica was severely damaged during the April 6, 2009 L’Aquila earthquake (MW 6.1). In particular, the area of the transept collapsed causing the dome to fall. A refined two-dimensional (2D) geotechnical model was built representing a section that includes the Basilica, in order to better understand the soil response of the Basilica site. The subsoil model was constrained using the geophysical and geotechnical data collected from the seismic microzonation studies, the reconstruction of private damaged buildings and other technical and scientific studies realized in the L’Aquila basin and in the area of the Basilica before and after L’Aquila earthquake. 2D site response analyses were performed to verify the presence of local site effects by comparing simulated versus experimental transfer functions. Moreover, a frequency–wavenumber (f–k) analysis was executed with the aim of evaluating the occurrence of surface waves generated within the basin. 2D seismic effects involve significant amplification in the period range of engineering interest, therein providing an appropriate elastic response spectrum for the restoration of the Basilica.

BIM ORIENTATION: GRADES OF GENERATION AND INFORMATION FOR DIFFERENT TYPE OF ANALYSIS AND MANAGEMENT PROCESS

Abstract. Architecture, Engineering and Construction (AEC) industry is facing a great process re-engineering of the management procedures for new constructions, and recent studies show a significant increase of the benefits obtained through the use of Building Information Modelling (BIM) methodologies. This innovative approach needs new developments for information and communication technologies (ICT) in order to improve cooperation and interoperability among different actors and scientific disciplines. Accordingly, BIM could be described as a new tool capable of collect/analyse a great quantity of information (Big data) and improve the management of building during its life of cycle (LC). The main aim of this research is, in addition to a reduction in production times, reduce physical and financial resources (economic impact), to demonstrate how technology development can support a complex generative process with new digital tools (modelling impact). This paper reviews recent BIMs of different historical Italian buildings such as Basilica of Collemaggio in L’Aquila, Masegra Castle in Sondrio, Basilica of Saint Ambrose in Milan and Visconti Bridge in Lecco and carries out a methodological analysis to optimize output information and results combining different data and modelling techniques into a single hub (cloud service) through the use of new Grade of Generation (GoG) and Information (GoI) (management impact). Finally, this study shows the need to orient GoG and GoI for a different type of analysis, which requires a high Grade of Accuracy (GoA) and an Automatic Verification System (AVS ) at the same time.

Dynamics of masonry walls connected by a vibrating cable in a historic structure

An original parametric model is presented to describe the modal interactions characterizing the linearized free dynamics of a cable–beam system. The structural system is composed by two vertical cantilever beams, connected by a suspended nonlinear cable. A closed form solution is achieved for the linear eigenproblem governing the undamped small-amplitude vibrations. The eigensolution shows a rich scenario of frequency crossing and veering phenomena between global modes, dominated by the beam dynamics, and local modes, dominated by the cable vibrations. Veering phenomena are accompanied by modal hybridization processes. The role played by different parameters is discussed, with focus on the resonance regions. The discussion allows the identification of an updated set of parameters, which offers a satisfying explanation of some unexpected dynamic interactions, observed in the experimental behavior of the masonry walls of the Basilica of Collemaggio, a historic structure heavily damaged by the 2009 L’Aquila earthquake.

Structural analysis of stone masonry columns of the Basilica S. Maria di Collemaggio

The Basilica of Collemaggio in L’Aquila is one of the outstanding architectural heritage in Abruzzo Region. The church, built in the late XIII century, has experienced many earthquakes during its life, some of which caused damages to the masonry structures, requiring continuous interventions and renovations. The last strong earthquake (April 6th, 2009) caused the collapse of the transept structures and significant damages in the apses area.Since 2009, several research groups have focused their attention on the Basilica, both from architectural and structural point of view. Particularly, recent studies have pointed out the historical value of nave columns, which seem to be XIII century authentic elements.Despite the magnitude of the last earthquake, the columns have proved limited resistance against seismic loads, resulting in a widespread damage, but without reaching the collapse. The aim of the present paper is to understand their structural behavior under horizontal actions.An overall finite element model of the church has been developed to perform eigenvalue and response spectrum analyses of the Basilica.Afterwards, a representative nave column has been studied considering both geometrical and mechanical non-linearity. In order to obtain a reliable evaluation of its structural behavior, two different models have been developed: an analytical model and a solid-brick finite element one.The performed analyses have allowed the evaluation of the stresses redistribution inside the columns after cracking. The results, provided in terms of force–displacement curve and stress contours, have permitted to identify some possible explanations about the columns seismic response.

Introspection on improper seismic retrofit of Basilica Santa Maria di Collemaggio after 2009 Italian earthquake

The 2009 L’Aquila, Italy earthquake highlighted the seismic vulnerability of historic masonry building structures due to improper “strengthening” retrofit work that has been done in the last 50 years. Italian seismic standards recommend the use of traditional reinforcement techniques such as replacing the original wooden roof structure with new reinforced concrete (RC) or steel elements, inserting RC tie-beams in the masonry and new RC floors, and using RC jacketing on the shear walls. The L’Aquila earthquake revealed the numerous limitations of these interventions, because they led to increased seismic forces (due to greater additional weight) and to deformation incompatibilities of the incorporated elements with the existing masonry walls. This paper provides a discussion of technical issues pertaining to the seismic retrofit of the Santa Maria di Collemaggio Basilica and in particular, the limitations of the last (2000) retrofit intervention. Considerable damage was caused to the church because of questionable actions and incorrect and improper technical choices.

Seismic Behavior of some Basilica Churches after L’Aquila 2009 Earthquake

In this paper the seismic response of four church buildings in the l’Aquila April 2009 earthquake is analyzed. The buildings are: St. Giusta church, St. Maria di Collemaggio Basilica, St. Silvestro church and St. Pietro di Coppito church. The analyses are carried out by employing a “two-step” procedure suggested by the authors and already applied to similar case studies. The first step consists in three-dimensional linear analysis, while in the second step, two-dimensional non-linear analyses of macro-elements are carried out. The results coming from the two-steps, allow for understanding the observed damage and for approximately assessing the seismic level of the building.

Ground penetrating radar investigations for the restoration of historic buildings: the case study of the Collemaggio Basilica (L’Aquila, Italy)

Ground penetrating radar (GPR) surveys were applied in the preliminary stage of a project of structural monitoring and restoration of the facade of the Collemaggio Basilica, a medieval church located in L’Aquila (central Italy). GPR surveys were very useful in evaluating the state of conservation of the facade and in identifying the thickness of its walls, the forms and deterioration of its masonry with its ashlar facing and rubble core, and the forms and locations of its middle cornice supports. GPR was demonstrated to be an ideal non-destructive method to investigate ancient structures of high cultural and historical value.