Non-Smooth Dynamic Analysis of Local Seismic Damage Mechanisms of the San Felice Fortress in Northern Italy

Abstract The May 2012 seismic swarm, with epicenter in the Modena plane, in Northern Italy, had severe consequences on the historical buildings of the area. In particular, the fortified structures suffered specific, recurring damage and collapse mechanisms. The present paper deals with the case of the San Felice sul Panaro Fortress, which saw the collapse of 4 out of 5 towers and many other global and local effects. The work starts with an in-depth knowledge path, as a fundamental premise for a conscious intervention. The combination among historical analysis of the building, seismic history of the site, materials and pathological survey, structural identification, on-site inspections and tests, allowed to interpret the crack pattern and to identify the damage mechanisms activated by the earthquake, successively examined with specific structural analyses. In particular, the present paper concentrates on the numerical modelling of the identified local mechanisms, adopting a type of analysis first developed at the University of Parma for applied mechanics, based on the use of non-smooth dynamics software, through a Differential Variational Inequalities (DVI) formulation specifically developed for the 3D discrete elements method. It allows to follow large displacements and the opening and closure of cracks in dynamic field. Once the modelling instrument was calibrated, thanks to the comparison with the real damages previously inspected, it was also applied to foresee the behavior of the same mechanisms with different actions and with different types of strengthening

THE USE OF GIS FOR THE APPLICATION OF THE PHENOMENOLOGICAL APPROACH TO THE SEISMIC RISK ANALYSIS: THE CASE OF THE ITALIAN FORTIFIED ARCHITECTURE

The present paper proposes the use of GIS for the application of the so-called phenomenological approach to the analysis of the seismic behaviour of historical buildings. This approach is based on the awareness that the different masonry building typologies are characterized by different, recurring vulnerabilities. Thus, the observation and classification of the real damage is seen as the first step for recognizing and classifying these vulnerabilities, in order to plan focused preventive interventions. For these purposes, the GIS has proven to be a powerful instrument to collect and manage this type of information on a large number of cases. This paper specifically focuses on the application of the phenomenological approach to the analysis of the seismic behaviour of fortified buildings, including castles, fortresses, citadels, and all the typical historical constructions characterized by the presence of massive towers and defensive walls. The main earthquakes which struck Italy in the last 40 years (up to the recent Central Italy seismic swarm) were taken into consideration and described by means of shake maps. A previously published work has been continued with the addition of new data and some improvements, including a specific symbology for the description of building typologies and conservation status on the maps, the indications of damage levels and the comparison between shake maps in terms of pga and in terms of pseudo-acceleration. The increase in knowledge obtained and the broader frame given by the analysis of the data are here directed to the primary aim of cultural heritage preservation

A Comparison Between Traditional and Modern Approaches for the Structural Modelling of Brick Masonry Barrel Vaults

Masonry vaults are widespread and characteristic structural elements of our built heritage since many centuries, but for a very long time they were built only based upon the experience and the proportional analysis of previous positive examples. Since the Hooke’s observations, in 17th century, about the shape of the catenary, and the first graphical analyses of 18th century, the tools for their “scientific” calculation have developed quickly [1], mainly to assess the stability of already existing structures rather than for the prevision of the future behaviour of new vaults. Despite the great progress in this field, ordinary programs for the static and seismic assessment of masonry buildings often disregard the vaults structural role and the professionals sometimes underestimate it, also due to the lack of attention dedicated to these structures by the technical codes. Therefore it seems now important to reconnect the elements of this modelling historical evolution, to compare the different methods and to find an equilibrium between complexity and reliability, making it accessible also to the common professional use, whose effects on preservation are important. To this aim, a pavilion vault was chosen as a reference, with given geometries and materials features, and the different methods were applied. On one side, traditional methods were chosen: the graphic Méry method [2] and the static theorem of limit analysis [3] have been applied to a system of 2D arches composing the vault. On the other side, a 2D Finite Element Model and the edge cutting ChronoEngine Distinct Element Model [4] have been also tested, under the same conditions. The influence of the brick pattern on the structural behaviour have been considered, conveniently defining the arches decomposition in the traditional methods and the blocks division in the Distinct Element Method. In all cases, calculations have been made changing both values and positions of the loads. The results are compared both in terms of stresses inside the masonry and in terms of deformation of the structural elements, evaluating the types of information and detail that the different approaches can supply. The results of the advanced numerical methods allow to assess the validity of the traditional approaches. On the other side, the possible contribution of the traditional methods to the calibration of the parameters for the numerical models is also discussed

Seismic vulnerability of old Italian fortifications

The damages recorded in the recent seismic events have highlighted that also very robust structures, such as old castles, are vulnerable with respect to not too high seismic actions. However, the damages have allowed not only of understanding the structural behavior of these ancient old fortifications, but also the influence of many factors affecting the specific response. In this paper an overview of the most recent developments in the seismic assessment of Italian medieval castles is presented. The study discusses on the identification of the most vulnerable elements and on their analytical evaluation. Then, an application to an ancient castle chosen as case study is shown

Advances in Computational Analysis of Masonry Structures

Nowadays, numerical models aid significantly the engineers in the structural assessment of ordinary and monumental existing masonry buildings. Indeed, these models can be used to predict the structural response to extraordinary loads, and so to evaluate the main weaknesses and the safety of a masonry structure. Nevertheless, given the deep complexities and uncertainties which characterize the geometry of historic buildings and the mechanical response of masonry, the computational analysis of masonry structures is still a challenging task. In this thesis, some recent advances in computational analysis of masonry structures are presented. Essentially, after a comprehensive review of the existing modeling strategies for masonry structures, the advancements pursued in the framework of mesh generation procedures for historic monumental buildings, analysis of seismically interacting structures, analysis of leaning historic structures, and block-based modeling of masonry structures, are shown and discussed

Surveying and Three-Dimensional Modeling for Preservation and Structural Analysis of Cultural Heritage

Dense point clouds can be used for three important steps in structural analysis, in the field of cultural heritage, regardless of which instrument it was used for acquisition data. Firstly, they allow deriving the geometric part of a finite element (FE) model automatically or semi-automatically. User input is mainly required to complement invisible parts and boundaries of the structure, and to assign meaningful approximate physical parameters. Secondly, FE model obtained from point clouds can be used to estimate better and more precise parameters of the structural analysis, i.e., to train the FE model. Finally, the definition of a correct Level of Detail about the three-dimensional model, deriving from the initial point cloud, can be used to define the limit beyond which the structural analysis is compromised, or anyway less precise. In this work of research, this will be demonstrated using three different case studies of buildings, consisting mainly of masonry, measured through terrestrial laser scanning and photogrammetric acquisitions. This approach is not a typical study for geomatics analysis, but its challenges allow studying benefits and limitations. The results and the proposed approaches could represent a step towards a multidisciplinary approach where Geomatics can play a critical role in the monitoring and civil engineering field. Furthermore, through a geometrical reconstruction, different analyses and comparisons are possible, in order to evaluate how the numerical model is accurate. In fact, the discrepancies between the different results allow to evaluate how, from a geometric and simplified modeling, important details can be lost. This causes, for example, modifications in terms of mass and volume of the structure

Performance-based damage assessment of masonry structures subjected to settlement using rigid block models

The issue of built Cultural Heritage (CH) exposed to natural hazards is a challenging topic in both research and engineering practice. In the last decades, many efforts were addressed to the protection of CH against seismic hazard, which is the main threat for the integrity and stability of structures. On the other hand, settlements induced by hydrogeological phenomena such as subsidence and landslides also represent a severe risk for existing buildings. Nevertheless, the investigation of damage induced by settlements on structures is a still open challenge. Empirical approaches were proposed, commonly based on the assessment of damage in terms of local parameters, e.g. crack widths. However, the severity of crack width can be affected by different factors such as structural configuration, masonry texture and material properties. Thus, models for the quantitative assessment of damage in terms of global safety levels of structures subjected to foundation movements are demanded. In this framework, this dissertation thesis aims at the development and application of a numerical approach based on rigid block modelling for the performance-based damage assessment of masonry structures subjected to settlement. Two in-house numerical models are proposed, namely a rigid block model with rigid contacts for the linear kinematic analysis and a rigid block model with no-tension elastic contacts for the non-linear kinematic analysis. The first tool aims at the prediction of the failure shape for settled structures as well as the value of the base reaction at the onset of mechanism. It is worth noting that masonry buildings usually exhibit a resilient safety behaviour with respect to settlements. Conversely, appropriate considerations of serviceability limit state are demanded to control damage on the structure and preserve the aesthetics. To this end, the non-linear kinematic model aims to predict the response of masonry structures under settlements also in the early damage states. The output is mainly represented by specific capacity curves, named "push-down curves", where the loss of base reaction is plotted as a function of the displacement of a control point at the settling support. Thus, the numerical formulation allows the damage propagation monitoring, from crack opening until incipient collapse. The dissertation thesis explores the possibility to use such a capacity curve to propose criteria for the displacement-based damage assessment and quantification. A comparison of the proposed approach with empirical damage classification methods is performed

Fault zone architecture, microstructures, deformation mechanisms and frictional behaviour of seismogenic, shallow-crustal, lithologically heterogeneous faults

Earthquakes that rupture the Earth’s surface are typically the most damaging and highlight the need for us to better constrain the style of deformation and frictional behaviour of fault zones in the shallow crust. This thesis presents two studies of natural, seismogenic, shallow crustal fault zones: 1) the Gubbio fault zone, which has been exhumed from 2.5-3 km depth and deforms a mixture of limestone and phyllosilicate-rich marly limestone; and 2) the Masada fault zone, which deforms near-surface, poorly lithified lake sediments. Field studies were complemented by low- and high-velocity rotary shear experiments to constrain the frictional behaviours of the naturally observed fault gouges under representative conditions. In addition, microstructural analyses of both naturally- and experimentally-produced fault rocks were performed in order to constrain the deformation mechanisms operating during fault slip. Our results show that the dominant deformation mechanisms operating within a fault zone, which are highly variable depending on environmental conditions such as depth, fault rock composition, fluid presence and composition, and strain-rate, will control: 1) fault zone architecture and therefore the distribution of seismicity; and 2) slip zone processes, which can subsequently affect the frictional behaviour of a fault, and also determine whether or not signatures of seismic slip are produced during rupture propagation. These are useful tools for geologists when trying to decipher the seismic history of natural faults. Frictional behaviour, in terms of the likelihood of rupture propagation through the shallow crust, is also found to vary significantly as a function of the aforementioned environmental conditions. A fuller knowledge of spatial, and possible temporal, variations in fault zone properties is therefore essential if more accurate earthquake forecasting models and assessments of their associated hazards are to be produced

Geotechnical Engineering for the Preservation of Monuments and Historic Sites III

The conservation of monuments and historic sites is one of the most challenging problems facing modern civilization. It involves, in inextricable patterns, factors belonging to different fields (cultural, humanistic, social, technical, economical, administrative) and the requirements of safety and use appear to be (or often are) in conflict with the respect of the integrity of the monuments. The complexity of the topic is such that a shared framework of reference is still lacking among art historians, architects, structural and geotechnical engineers. The complexity of the subject is such that a shared frame of reference is still lacking among art historians, architects, architectural and geotechnical engineers. And while there are exemplary cases of an integral approach to each building element with its static and architectural function, as a material witness to the culture and construction techniques of the original historical period, there are still examples of uncritical reliance on modern technology leading to the substitution from earlier structures to new ones, preserving only the iconic look of the original monument. Geotechnical Engineering for the Preservation of Monuments and Historic Sites III collects the contributions to the eponymous 3rd International ISSMGE TC301 Symposium (Naples, Italy, 22-24 June 2022). The papers cover a wide range of topics, which include: 　 - Principles of conservation, maintenance strategies, case histories - The knowledge: investigations and monitoring - Seismic risk, site effects, soil structure interaction - Effects of urban development and tunnelling on built heritage - Preservation of diffuse heritage: soil instability, subsidence, environmental damages The present volume aims at geotechnical engineers and academics involved in the preservation of monuments and historic sites worldwide