Papers by Giorgia Giardina
Earthquakes are natural hazards leading to the greatest human and economic losses, which are most... more Earthquakes are natural hazards leading to the greatest human and economic losses, which are mostly due to structural collapses. Rapid identification and assessment of earthquake-induced damage to structures is therefore an essential component of the emergency response, and instrumental to effective reconstruction plans. Typically, structural damage assessment is conducted through building-by-building inspections during post-earthquake field reconnaissance missions. These missions are expensive and time-consuming, especially if large areas need to be investigated. Remote sensing techniques provide a relatively low-cost, wide-area alternative to in-situ monitoring. Classification and change detection based on pre- and post-event optical and synthetic aperture radar (SAR) satellite images are the most used approaches to detect damaged structures after earthquakes. However, these techniques only provide qualitative observations of collapsed or severely damaged structures. In this work,...
Proceedings of the Institution of Civil Engineers - Geotechnical Engineering
Disclaimer The AM is yet to be copyedited and formatted in journal house style but can still be r... more Disclaimer The AM is yet to be copyedited and formatted in journal house style but can still be read and referenced by quoting its unique reference number, the digital object identifier (DOI). Once the AM has been typeset, an 'uncorrected proof' PDF will replace the 'accepted manuscript' PDF. These formatted articles may still be corrected by the authors. During the Production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal relate to these versions also. Version of record The final edited article will be published in PDF and HTML and will contain all author corrections and is considered the version of record. Authors wishing to reference an article published Ahead of Print should quote its DOI. When an issue becomes available, queuing Ahead of Print articles will move to that issue's Table of Contents. When the article is published in a journal issue, the full reference should be cited in addition to the DOI.
Frontiers in Built Environment
On 14th August 2021, a magnitude 7.2 earthquake struck the Tiburon Peninsula in the Caribbean nat... more On 14th August 2021, a magnitude 7.2 earthquake struck the Tiburon Peninsula in the Caribbean nation of Haiti, approximately 150 km west of the capital Port-au-Prince. Aftershocks up to moment magnitude 5.7 followed and over 1,000 landslides were triggered. These events led to over 2,000 fatalities, 15,000 injuries and more than 137,000 structural failures. The economic impact is of the order of US$1.6 billion. The on-going Covid pandemic and a complex political and security situation in Haiti meant that deploying earthquake engineers from the UK to assess structural damage and identify lessons for future building construction was impractical. Instead, the Earthquake Engineering Field Investigation Team (EEFIT) carried out a hybrid mission, modelled on the previous EEFIT Aegean Mission of 2020. The objectives were: to use open-source information, particularly remote sensing data such as InSAR and Optical/Multispectral imagery, to characterise the earthquake and associated hazards; t...
Fringe 2021 - 11th International Workshop on “Advances in the Science and Applications of SAR Interferometry and Sentinel-1 InSAR”, Jun 4, 2021
RILEM Bookseries, 2019
Structural monitoring of surface building displacements is a significant component of the total f... more Structural monitoring of surface building displacements is a significant component of the total financial investment for underground construction projects in urban areas. While traditional monitoring requires in-situ (terrestrial) measurements and trigger levels based on preliminary evaluation of vulnerable structures, very recent advances in Interferometric Synthetic Aperture Radar (InSAR) techniques enable remote monitoring over extensive areas, providing rapid, semi-automatic, and dense measurements with millimetre accuracy. Despite the well-established use of InSAR in geophysical applications, only a few studies are currently available on the use of satellite-based monitoring for the assessment of building deformations and structural damage. The aim of this project is to investigate the potential of InSAR monitoring data as an input to post-tunnelling damage assessment procedures. First, InSAR-based measurements of building displacements, induced by the excavation of Crossrail tunnels in London, were acquired and processed. Then, following the definition of a step-by-step procedure, the satellite-based building displacements were used to evaluate structural deformation parameters typically used in extensive damage assessment procedures. Results show that the number of available measures per single building can enable the estimation of deformation parameters, a capability that is not economically feasible for large scale projects using traditional monitoring systems. The comparison with greenfield predictions offers new insight into the effect of soil-structure interaction and demonstrates the suitability of InSAR monitoring for post-tunnelling damage assessment of structures. The outcome of this work can have a significant economic impact on the construction industry and can advance the knowledge of building and infrastructure response to ground subsidence.
Structural Health Monitoring, 2022
Ageing stock and extreme weather events pose a threat to the safety of infrastructure networks. I... more Ageing stock and extreme weather events pose a threat to the safety of infrastructure networks. In most countries, funding allocated to infrastructure management is insufficient to perform systematic inspections over large transport networks. As a result, early signs of distress can develop unnoticed, potentially leading to catastrophic structural failures. Over the past 20 years, a wealth of literature has demonstrated the capability of satellite-based Synthetic Aperture Radar Interferometry (InSAR) to accurately detect surface deformations of different types of assets. Thanks to the high accuracy and spatial density of measurements, and a short revisit time, space-borne remote-sensing techniques have the potential to provide a cost-effective and near real-time monitoring tool. Whilst InSAR techniques offer an effective approach for structural health monitoring, they also provide a large amount of data. For civil engineering procedures, these need to be analysed in combination with...
Proceedings of the Institution of Civil Engineers - Bridge Engineering, 2022
Worldwide, transport infrastructure is increasingly vulnerable to aging-induced deterioration and... more Worldwide, transport infrastructure is increasingly vulnerable to aging-induced deterioration and climate-related hazards. Often, inspection and maintenance costs far exceed the available resources, and numerous assets lack any rigorous structural evaluation. Space-borne synthetic aperture radar interferometry (InSAR) is a powerful remote sensing technology that can provide cheaper deformation measurements for bridges and other transport infrastructure with short revisit times, while scaling from the local to the global scale. As recent studies have shown InSAR accuracy to be comparable to that of traditional monitoring instruments, InSAR could offer a cost-effective tool for long-term, near-continuous deformation monitoring, with the possibility of supporting inspection planning and maintenance prioritisation while maximising functionality and increasing the resilience of infrastructure networks. However, despite the high potential of InSAR for structural monitoring, some important...
Research data supporting "The role of building position on the response of buildings to tunn... more Research data supporting "The role of building position on the response of buildings to tunnelling subsidence: numerical modelling"
For urban tunneling projects it is essential to predict and prevent building damage. Although var... more For urban tunneling projects it is essential to predict and prevent building damage. Although various case studies and experiments have shown that buildings considerably modify greenfield soil movements, widely accepted damage assessment methods neglect this soil-structure interaction and simplify structures as linear elastic beams. This paper summarizes an experimental investigation of the response of more realistic structures to tunneling-induced deformations. Small scale structural models with facade openings and brittle material properties were 3D printed and tested in a geotechnical centrifuge. Soil and structure displacement data were obtained by image-based measurement. Results demonstrate that structures notably mitigate differential greenfield ground displacements. It is also shown that maximum soil settlements, horizontal soil displacements beneath the structure and structural damage in the form of cracking significantly depend on the position of the structure in the settl...
12th International Conference on Structural Analysis of Historical Constructions, 2021
Deciding whether crack patterns are similar is one of the main components in damage assessment of... more Deciding whether crack patterns are similar is one of the main components in damage assessment of masonry structures, since the degree of similarity between patterns often correlates with the likelihood of having similar causes. Hence, quantifying crack pattern similarity is instrumental in understanding damage. Similarity checks usually take place in experts' mind, comparing an observed pattern with hundreds of patterns they have seen in the past and recorded in their memory. The observed pattern is then related to damage causes they find the most plausible based on their experience, understanding of physics, and local conditions. Currently, it is not understood how the crack pattern comparisons are made by the human brain and experts have difficulties in verbalizing and formalizing their decision making process. Therefore, deciding on the similarity of masonry crack patterns is solely performed by experts. This approach is expensive, limited by the availability of experts, and yields only qualitative answers.
This paper presents a recent case study of monitoring the effects of piling on an adjacent old ma... more This paper presents a recent case study of monitoring the effects of piling on an adjacent old masonry vault in London. The monitoring scheme consists of 3 independent instrumentation sets that provide different types of information: (a) discrete total station point targets, (b) linear distributed fibre optic cable sensors and (c) surface distributed laser scanners. The availability of these sensors is able to shed some light on the actual response of the masonry structure through precise displacements and high-accuracy localised strains. The collected monitoring data show the location of cracks and provide indications for their opening magnitude. Relevant numerical analyses have also been conducted using (a) limit analysis mechanisms and (b) finite element deformation analysis which confirmed the observed field deformation mechanism and the presence of cracks within the structure. It is shown that such innovative sensing approaches can provide valuable detailed information about the real behaviour of structures that were not available before.
This is the final version of the article. It first appeared from EUROFUGE via http://eurofuge2016... more This is the final version of the article. It first appeared from EUROFUGE via http://eurofuge2016.ifsttar.fr/home/
Structural Control and Health Monitoring, 2021
Structural deformation monitoring is crucial for the identification of early signs of tunnelling-... more Structural deformation monitoring is crucial for the identification of early signs of tunnelling-induced damage to adjacent structures and for the improvement of current damage assessment procedures. Satellite multi-temporal interferometric synthetic aperture radar (MT-InSAR) techniques enable measurement of building displacements over time with millimetre-scale accuracy. Compared to traditional ground-based monitoring, MT-InSAR can yield denser and cheaper building observations, representing a cost-effective monitoring tool. However, without integrating MT-InSAR techniques and structural assessment, the potential of InSAR monitoring cannot be fully exploited. This integration is particularly demanding for large construction projects, where big datasets need to be processed. In this paper, we present a new automated methodology that integrates MT-InSAR-based building deformations and damage assessment procedures to evaluate settlement-induced damage to buildings adjacent to tunnel excavations. The developed methodology was applied to the buildings along an 8-km segment of the Crossrail tunnel route in London, using COSMO-SkyMed MT-InSAR data from 2011 to 2015. The methodology enabled the identification of damage levels for 858 buildings along the Crossrail twin tunnels, providing an unprecedented number of high quality field observations for building response to settlements. The proposed methodology can be used to improve current damage assessment procedures, for the benefit of future underground excavation projects in urban areas.
The authors are grateful to EPSRC grant EP/KP018221/1 and Crossrail for providing financial support.
2021 IEEE International Geoscience and Remote Sensing Symposium IGARSS, 2021
In western countries, thousands of infrastructure assets have exceeded their intended design life... more In western countries, thousands of infrastructure assets have exceeded their intended design life and need continuous monitoring. Space-borne Interferometric Synthetic Aperture Radars (InSAR) are capable of wide-area monitoring, providing inexpensive and high-density measurements of buildings and infrastructure deformations with a millimetre-scale accuracy. Infrastructure catalogues can be used to associate the InSAR-based measurements with the corresponding structures. However, when large infrastructure networks are analysed, the manual extraction of the relevant InSAR-derived displacements is not feasible. In this paper, a new methodology based on the automated integration of InSAR-based displacements and infrastructure databases to warn potentially anomalous deformations over large infrastructure networks is presented. The proposed methodology is applied to the Los Angeles highway and freeway network, using Sentinel data from 2016 to 2019. Results can have a direct impact on transportation network management.
International Journal of Architectural Heritage, 2019
Historic masonry structures are particularly sensitive to differential soil settlements. These se... more Historic masonry structures are particularly sensitive to differential soil settlements. These settlements may be caused by deformable soil, shallow or inadequate foundation, structural additions in the building and changes in the underground water table due to the large-scale land use change in urban areas. This paper deals with the numerical modeling of a church nave wall subjected to differential settlement caused by a combination of the above factors. The building in question, the church of Saint Jacob in Leuven, has suffered extensive damage caused by centuries-long settlement. A numerical simulation campaign is carried out in order to reproduce and interpret the cracking damage observed in the building. The numerical analyses are based on material and soil property determination, the monitoring of settlement in the church over an extended period of time and soil-structure interaction. A sensitivity study is carried out, focused on the effect of material parameters on the response in terms of settlement magnitude and crack width and extent. Soil consolidation over time is considered through an analytical approach. The numerical results are compared with the in-situ observed pathology and with an analytical damage prediction model.
Journal of Geotechnical and Geoenvironmental Engineering, 2020
Some of the authors of this publication are also working on these related projects: Greenfield tu... more Some of the authors of this publication are also working on these related projects: Greenfield tunnelling in sands View project Tunnelling beneath piled structures in urban areas (TUBEURB)-MARIE SKŁODOWSKA-CURIE ACTIONS Individual Fellowship (IF) View project
Proceedings of the Institution of Civil Engineers - Geotechnical Engineering, 2019
Building monitoring and protection are important components of underground projects in urban area... more Building monitoring and protection are important components of underground projects in urban areas. Typically the procedures applied for the assessment of settlement-induced damage to buildings are based on simplified assumptions that do not take into account soil–structure interaction. Assessment methods based on the relative stiffness between the structure and the soil exist, but they are rarely applied in practice due to concerns about the accuracy and reliability. The primary aim of this work is to use the large amount of monitoring data provided by the Crossrail project in London to improve understanding of building performance and existing damage assessment methods. The paper gives an initial overview of the available monitoring data by presenting four representative case studies for load-bearing masonry buildings on shallow foundations. Structural data are then used to evaluate the consistency of predictions produced by different relative stiffness formulations. The results s...
Tunnelling and Underground Space Technology, 2018
Current procedures for the assessment of buildings response to tunnelling take into account the e... more Current procedures for the assessment of buildings response to tunnelling take into account the effect of soilstructure interaction through the definition of the building stiffness relative to the soil stiffness. Limitations of these procedures are uncertainties in the evaluation of structural parameters and inconsistent results between different methods. In this paper, three existing formulations of the Relative Stiffness Method (RSM) were been critically evaluated by analysing the governing factors in the building stiffness calculation and their effect on the structural damage assessment. The results of a sensitivity study on building height, eccentricity, opening ratio, tunnel depth, soil and masonry stiffness, and trough width parameter quantified the effect of these factors on the considered RSMs. The application of different RSMs to a real masonry building adjacent to the Jubilee Line tunnel excavation highlighted the significant effect of window openings, façade stiffness and neutral axis position on the building stiffness calculation and deformation prediction. These results highlight the need for a consistent and robust damage assessment procedure.
Remote Sensing, 2019
We present a methodology for the assessment of possible pre-failure bridge deformations, based on... more We present a methodology for the assessment of possible pre-failure bridge deformations, based on Synthetic Aperture Radar (SAR) observations. We apply this methodology to obtain a detailed 15-year survey of the Morandi bridge (Polcevera Viaduct) in the form of relative displacements across the structure prior to its collapse on August 14th 2018. We generated a displacement map for the structure from space-based SAR measurements acquired by the Italian constellation COSMO-SkyMed and the European constellation Sentinel-1A/B over the period 2009–2018. Historical satellite datasets include Envisat data spanning 2003–2011. The map reveals that the bridge was undergoing an increased magnitude of deformations over time prior to its collapse. This technique shows that the deck next to the collapsed pier was characterized since 2015 by increasing relative displacements. The COSMO-SkyMed dataset reveals the increased deformation magnitude over time of several points located near the strands ...
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Papers by Giorgia Giardina