Analysis of a scaled stone masonry facade subjected to differential settlements

Historical masonry structures are vulnerable to differential settlements of the ground. This vulnerability is potentially higher for historic buildings on wooden pile foundations, which can have their bearing capacity reduced by material deterioration. In order to protect such buildings from the effect of soil subsidence it is therefore essential assessing their response to settlements. The aim of this paper is to investigate the settlement-induced damage on a stone masonry façade. For the first time, experimental testing and computational analyses were performed on a scaled model of a specific existing historic structure, the Loggia palace in Brescia, Italy. Differential settlements were applied to dry blocks and mortar joints models of the façade. Experimental results showed the capability of the façade to reach a new equilibrium configuration following the subsidence of two adjacent columns. This approach can be used to assess the behaviour of similar structures. The validated numerical model confirms the interpretation of the failure mechanism and has the potential to allow extending the approach to a wider range of settlement and structural scenarios, as well as to different buildings

Monitoring deformations of infrastructure networks:A fully automated GIS integration and analysis of InSAR time-series

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 large infrastructure inventories. Over a regional scale, the manual extraction of InSAR-derived displacements from individual assets is extremely time-consuming and an automated integration of the two datasets is essential to effectively assess infrastructure systems. This paper presents a new methodology based on the fully automated integration of InSAR-based measurements and Geographic Information System-infrastructure inventories to detect potential warnings over extensive transport networks. A Sentinel dataset from 2016 to 2019 is used to analyse the Los Angeles highway and freeway network, while the Italian motorway network is evaluated by using open access ERS/Envisat datasets between 1992 and 2010, COSMO-SkyMed datasets between 2008 and 2014 and Sentinel datasets between 2014 and 2020. To demonstrate the flexibility of the proposed methodology to different SAR sensors and infrastructure classes, the analysis of bridges and viaducts in the two test areas is also performed. The outcomes highlight the potential of the proposed methodology to be integrated into structural health monitoring systems and improve current procedures for transport network management.</p

Influence of building geometry on bending and shear deformations of buildings subject to tunnelling subsidence:centrifuge testing

Tunnelling-induced settlement damage to pre-existing buildings is a result of bending and shear deformations, which typically occur simultaneously. However, widely accepted methods to assess building damage caused by tunnelling subsidence focus only on the mode of deformation (i.e. shear or bending) that is assumed to govern the onset of building damage. Furthermore, building damage assessment methods typically relate the dominant mode of deformation to the length to height ratio, L/H, of the structure, while more recent research reported that facade openings significantly affect the dominant deformation mode. This paper presents a series of centrifuge tests that explore bending and shear effects on surface structures that are affected by a shallow tunnel excavation in sand. The tests were performed on3D printed building models with varying L/H ratio and facade openings. The response of these building models to the ground movements caused by the tunnelling operation is monitored using digital image correlation (DIC). Results show that bending deformations increase with the L/H ratio while shearing becomes dominant as the amount of facade openings increases. It is also shown that shearing and bending occur simultaneously and therefore should be combined in future damage assessment methods. The obtained experimental results provide essential benchmark data for computational modelling of tunnelling-induced settlement damage on surface structures, as presented in the companion paper

Influence of building geometry on bending and shear deformations of buildings subject to tunnelling subsidence:numerical modelling

Masonry buildings in urban areas can be damaged by differential ground movements caused by underground excavations. Existing procedures for the assessment of building damage due to excavation-induced settlements include the effect of the building on the settlement trough in terms of building stiffness relative to soil stiffness. In these procedures, the relative stiffness is calculated by considering either the bending stiffness or the shear stiffness of the building. In this paper, finite element modelling of buildings subjected to tunneling-induced settlements is used to determine the relative importance of shear and bending deformations in damage predictions. Computational modelling was first validated by simulating centrifuge tests on 3D printed small scale models of masonry buildings subjected to tunneling in sand. Using a similar modelling approach, a sensitivity study was then conducted on the governing effect of shear or bending deformations for different amounts of facade openings. Results indicate the need to include both shear and bending deformation in assessment procedures, and provide essential data towards this objective

A comparison of current analytical methods for predicting soil-structure interaction due to tunnelling

Current procedures for the assessment of buildings response to tunnelling take into account the effect of soil-structure 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) have 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 underlined 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.</p

Numerical Modeling of a Church Nave Wall Subjected to Differential Settlements::Soil-Structure Interaction, Time-Dependence and Sensitivity Analysis

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 damage and with an analytical damage prediction model.The authors acknowledge the funding received by BRAIN.be, Belspo in support of the GEPATAR research project (“GEotechnical and Patrimonial Archives Toolbox for ARchitectural conservation in Belgium” BR/132/A6/Gepatar).Peer ReviewedPostprint (author's final draft

Numerical analysis of settlement-induced damage to a masonry church nave wall

Differential soil settlements can induce structural damage to heritage buildings, causing not only economic but also cultural value losses. In 1963, the Saint Jacob’s church in Leuven was permanently closed to the public because of severe settlement-induced damage caused by insufficient bearing capacity of the founda- tion. Currently, the church is stabilized using a temporary shoring system. This work aims at implementing a practical modelling approach to predict damage on church nave walls subjected to differential settlements. For that purpose, a finite element model of the Saint Jacob’s church nave was generated and validated through on- site monitoring data including levelling, damage survey and laser scanningThis work was done within the framework of the GEPATAR project (“GEotechnical and Patrimonial Archives Toolbox for ARchitectural conservation in Belgium” BR/132/A6/Gepatar), supported by BRAIN.be, Belspo.Postprint (published version

Crack growth in masonry::Numerical analysis and sensitivity study for discrete and smeared crack modelling

One of the most common obstacles faced by engineers when making numerical models to assess damage in historical masonry lies in defining the most suitable constitutive models when there is shortage of either material characterization or experimental data. This paper presents the implementation of a 2D finite element model (FEM) of a masonry wall by means of two strategies: a discrete cracking meso-model and a continuum smeared cracking macro-model. A sensitivity study is performed to investigate the effect of material properties variation on both modelling strategies, each of which considers the highly non-linear behaviour as well as the brittle cracking of the masonry. The numerical models are validated through the results obtained from an experimental testing campaign which considered a brick masonry wall subjected to cyclic three-point bending. The results of both modelling strategies compared with experimental results are presented, as well as the criteria considered for material characterization and the sensitivity analysis. Results indicate the suitability of both models to reproduce experimentally observed load capacity, failure mechanism and horizontal deformations. However, the meso-model showed higher accuracy in terms of failure mechanism and plastic deformations. The sensitivity analysis indicated that some material parameters, such as fracture energy, cohesion and tensile strength, significantly govern the final cracking. This is an important criterion for adequately choosing the parameters for further models in which crack width is considered, e.g. for settlement-induced cracking analysis.</p