Exploring Problems and Prospective of Satellite Interferometric Data for the Seismic Structural Health Monitoring of Existing Buildings and Architectural Heritage

Satellite interferometric data represent a promising source of information for the Structural Health Monitoring (SHM) of the existing built environment. This is especially true because they show differential temporal-spatial displacements of remotely monitored points, which can be easily interpreted with a visual inspection of their time-histories for different locations defined a priori. However, the interferometric information is commonly referred to extended territories (at the scale of city or region), thus several problems arise in the implementation of automatic SHM techniques for the damage detection, localization, and assessment of the built environment at a point level (scale of the building or lower). Despite a long list of challenges, interferometric data have also the potential to become a useful source to assess the health of a structure, especially for helping in define structural early warning methodologies. For this reason, in the paper, the authors summarize the main challenges in the use of satellite interferometric data for civil SHM, and rather than proposing remedial actions, try to critically analyze the challenges and perspectives for future applications

Condition Assessment of an Early Thin Reinforced Concrete Vaulted System

For the analysis and conservation of architectural heritage a multi-disciplinary approach is required. In the specific case of early concrete buildings, survey and experimental investigations constitute a fundamental source of information for verifying the actual structural behavior and the residual safety levels. This paper reports the direct experience acquired from an extensive experimental campaign conducted on the Paraboloide in Casale Monferrato. The study aims to be an example of how condition assessment of the structural heritage of the early 1900s, with an apparently simple geometric shape and composition, can actually contribute in understanding hidden structural complexity. Moreover, this work may provide useful information to researchers and practitioners who are approaching this specific structural typology (e.g., the industrial heritage represented by parabolic concrete silos). In more details, results are presented regarding the in-situ investigations, and the laboratory tests carried out to analyze the mechanical performance inherent to both (i) local aspects of the structure, such as the quality of the materials and connections, and (ii) global aspects, such as the modal response of the structure. Furthermore, considerations are made on the results of the experimental campaign, also through the corroboration of numerical models

Understanding the structures of Pier Luigi Nervi: a multidisciplinary approach

[EN] The paper describes the strategies adopted to carry out the knowledge campaign on Hall C built by Pier Luigi Nervi at Torino Esposizioni, between 1949 and 1950, and belonging to the architectural heritage of the 20th century. The structure was built by combining reinforced concrete and ferrocement elements, thus implementing what for Nervi would later become the distinctive construction system of his artwork, which combined the use of precast in situ and cast-in-place elements.  The extensive review of the historical documentation allowed the identification of the distinctive features and material differences of all structural elements in order to formulate the least invasive testing campaign possible, combining sample extraction with non-destructive testing. The paper aims to illustrate the problems and challenges associated with the creation of interpretive models of the built heritage through the relationship between historical critical investigations and structural diagnosis and is intended to serve as an example for an appropriate phase of investigation aimed at developing guidelines for the conservation of a complex and iconic work.The present work is supported by the Keeping it Modern grant awarded by The Getty Foundation of Los Angeles (USA).Lenticchia, E.; Ceravolo, R.; Faccio, P. (2023). Understanding the structures of Pier Luigi Nervi: a multidisciplinary approach. VITRUVIO - International Journal of Architectural Technology and Sustainability. 8:66-75. https://doi.org/10.4995/vitruvio-ijats.2023.188626675

Sensor Placement Strategies for the Seismic Monitoring of Complex Vaulted Structures of the Modern Architectural Heritage

Effective diagnostic and monitoring systems are highly needed in the building and infrastructure sector, to provide a comprehensive assessment of the structural health state and improve the maintenance and restoration planning. Vibration-based techniques, and especially ambient vibration testing, have proved to be particularly suitable for both periodic and continuous monitoring of existing structures. As a general requirement, permanent systems must include a sensing network able to run a continuous surveillance and provide reliable analyses based on different information sources. The variability in the environmental and operating conditions needs to be accounted for in designing such a sensor network, but it is mainly the structural typology that governs the optimal sensor placement strategy. Architectural heritage consists of a great variety of buildings and monuments that significantly differ from each other in terms of typology, historic period, construction techniques, and materials. In this paper, the main issues regarding seismic protection and analysis of the modern architectural heritage are introduced and applied to one of the vaulted structures built by Pier Luigi Nervi in the Turin Exhibition Centre. The importance of attaining an adequate level of knowledge in historic structures is also highlighted. After an overview of the Turin Exhibition Centre and its construction innovations, this paper focuses on Hall B, describing the structural design conceived by Pier Luigi Nervi. A seismic assessment of the structures of Hall B is then presented, considering the potential seismic damage to nonstructural elements. Subsequently, the application of an optimal sensor placement strategy is described with reference to two different scenarios: the first one corresponding to the undamaged structure and the second one that considers a possible damage to the infill walls. Finally, a novel damage-scenario-driven sensor placement strategy based on a combination of the two above mentioned is proposed and discussed. One of the major conclusions drawn from the analyses performed is that nonstructural elements undergoing seismic damage or degradation may significantly affect the global dynamic response and consequently the optimal sensing configurations

AE propagation velocity calculation for stiffness estimation in Pier Luigi Nervi’s concrete structures

Abstract In the present paper, the acoustic emission (AE) device is used with an innovative approach, based on the calculation of P-wave propagation velocity (vp ), to detect the stiffness characteristics and the diffused damage of in-service old concrete structures. The paper presents the result of a recent testing campaign carried out on the slant pillars composing the vertical bearing structures designed by Pier Luigi Nervi in one of his most iconic buildings: the Hall B of Torino Esposizioni. In order to investigate the properties of these inclined pillars, localizations of artificial sources (hammer impacts), by the triangulation procedure, were performed on three different inclined elements characterized by stiffness discrepancies due to different causes: the casting procedures, executed in different stages, and the enlargement of the hall happened a few years later the beginning of the construction. In the present work, the relationship between the velocity of AE signals and the elastic characteristics (principally elastic modulus, E) is evaluated in order to discriminate the stiffness level of the slanted pillars. The procedure presented made it possible to develop an innovative investigation method able to estimate, by means of AE, the state of conservation and the elastic properties and the damage level of the monitored concrete and reinforced concrete structures

Synergistic and combinatorial optimization of finite element models for monitored buildings

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Towards the Seismic Monitoring of a Monumental Structure in Mixed Masonry-RC

The monumental historical heritage is recognized and appreciated worldwide. It is the result of the succession of different cultures that have inevitably influenced and characterized history; therefore, it represents an inestimable value to be preserved for future generations in order to transmit culture and art. In addition, there is a growing engineering interest in the protection of cultural heritage since it is strongly vulnerable. In the present work, the authors present the first attempt of geometric and mechanical modeling (Finite Element Model) and the subsequent sensitivity analysis of the Upper Basilica of the Sanctuary of Oropa (Chiesa Nuova), characterized by a mixed structure in masonry and reinforced concrete. The analysis conducted is placed at the beginning of a path of knowledge which, in subsequent steps, allows the understanding of the static and dynamic behavior of the analyzed structure. The goal of this work is to discriminate and validate which of the elastic parameters characterizing the individual components of the structure have a significant effect on the dynamic response of the structure, to facilitate the subsequent analysis aimed at defining the dynamic monitoring sensing system to be installed on the structure, and to support vulnerability analyses

Analysis of the possible geometries of a disappeared Parthian adobe dome: from in-situ tests to finite element macro-modelling

The work studies - from a structural point of view - the possible geometries of the adobe dome covering the Round Hall building in the archaeological site of Old Nisa (Turkmenistan). Thirteen dome geometries are identified, starting from archaeological reconstructions of the disappeared dome. The dome reconstructions are subsequently modelled through nonlinear finite element analysis in order to check their static behaviour. Concrete damage plasticity model is used to describe the nonlinear behaviour of adobe masonry. To calibrate the material model, the results of an onsite experimental program characterising adobe bricks are used. The analyses show that all the 13 geometries are stable with large safety margins. The results do not allow excluding some geometries, but on the contrary, highlight that the choice of the geometry of the dome was not a critical element. This aspect supports the hypothesis that the round room was actually covered by a dome

ANALYSIS OF THE DAMAGE STATE OF A MONUMENTAL BUILDING BY CONSIDERING THE VARIATIONS IN SOIL CONDITIONS

This paper investigates whether it is possible to identify the influence of soil conditions on the modal parameters of the structure for damage detection and overall structural health monitoring. To do so, the data gathered on a large monumental building damaged by differ-ential settlements are analyzed. In particular the dynamic response of the case study, a large monumental masonry building, was experimentally investigated within an operational modal analysis (OMA) campaign. Mechanical data obtained from the geophysical tests were in turn employed to build and characterize a numerical model of the soil underlying and sur-rounding the building. The resulting model was then used to study the sensitivity of the mod-al charasteristics of the building with respect to variations of external environmental factors (e.g., the water table level) which affect the underlying soil. The results obtained from this numerical study is deemed to represent a starting point for future experimental tests and investigations, whose final aim is relating ambient vibration measurement to the occurrence of differential settlements or subsidence, in order to detect progressive, and possibly pathological, behaviors

Combining satellite geophysical data with continuous on-site measurements for monitoring the dynamic parameters of civil structures

One key issue in the Structural Health Monitoring (SHM) of buildings is the influence of the soil on the dynamics of the system. The lack of accurate information on soil-structure interaction represents a source of significant uncertainty and generates difficulties in assessing the state of structural health. In this respect, satellite data could represent a valuable tool for soil knowledge. This paper presents the first study of satellite data coming from the environmental Copernicus program of the European Space Agency (ESA) for the alternative application in the field of SHM. In particular, Land Surface Temperature (LST) and Soil Water Index (SWI) data are elected to study surface temperature and moisture condition of the soil. Once examined and processed, these records have been statistically analyzed, crossed with on-site experimental quantities (natural frequencies and environmental variations), and given as input to a Finite Element (FE) model. The final goal is to understand the actual structural behavior, but also to monitor the evolution of the dynamic parameters for the purposes of structural and seismic monitoring. The largest oval masonry dome in the world was chosen as a prominent case study to demonstrate this novel approach to SHM