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This paper presents a framework to enable probabilistic assessment for braced excavation-induced structural damage on a regional scale. Random filed models are created to describe the uncertainties of spatially variable ground displacements induced by excavation, and random variables are adopted to model the uncertainties of soil stiffnesses, structural stiffnesses, and building weights. The uncertainties are propagated to the probability distributions of building characteristic tensile strains (εc) through a Monte-Carlo method, in which a 3-dimensional (3D) soil-structure interaction (SSI) model is evaluated in each simulation. With limit state functions defined based on εc, damage probabilities were quantified for all buildings in the region impacted by the excavation. Fragility heatmaps that can be used for estimating the probabilities of each possible damage state from impact level were also generated for each building. The framework is demonstrated with an excavation case history executed in Oslo, Norway. The 3D SSI model adopted in the framework can provide more accurate building response prediction than conventional 2D analysis. Meanwhile, the probabilistic assessment method provides a tool to quantify the uncertainty effect in the building assessment of large excavation construction.

Understanding the strain transfer mechanism is required to interpret strain sensing results for fiber optic cables. The strain transfer mechanism for fiber optic cables embedded in cementitious materials has yet to be thoroughly investigated experimentally. Interpretation of fiber optic sensing results is of particular concern when there is a displacement discontinuity. This study investigates the strain transfer mechanism for different types of fiber optic cables while embedded in concrete cubes, sustaining a boundary condition which features a displacement discontinuity. The strain transfer mechanisms for different cables are compared under increasing strain levels. Under cyclic loading, the nonlinear behavior of the force-displacement relation and of the strain distribution in the fiber optic cable are discussed. The mechanical properties of the fiber optic cables are presented and discussed. A parameter is proposed to quantify the strain transfer length. The results of this study will assist researchers and engineers to select appropriate cables for strain sensing and interpret the fiber optic sensing results.

Distributed fiber-optic sensing (DFOS) technologies have been used for decades to detect damage in infrastructure. One recent DFOS technology, Optical Frequency Domain Reflectometry (OFDR), has attracted attention from the structural engineering community because its high spatial resolution and refined accuracy could enable new monitoring possibilities and new insight regarding the behavior of reinforced concrete (RC) structures. The current research project explores the ability and potential of OFDR to measure distributed strain in RC structures through laboratory tests on an innovative beam-column connection, in which a partial slot joint was introduced between the beam and the column to control damage. In the test specimen, fiber-optic cables were embedded in both the steel reinforcement and concrete. The specimen was tested under quasi-static cyclic loading with increasing displacement demand at the structural laboratory of the Pacific Earthquake Engineering Research (PEER) Center of UC Berkeley. Different types of fiber-optic cables were embedded both in the concrete and the rebar. The influence of the cable coating and cable position are discussed. The DFOS results are compared with traditional measurements (DIC and LVDT). The high resolution of DFOS at small deformations provides new insights regarding the mechanical behavior of the slotted RC beam-column connection, including direct measurement of beam curvature, rebar deformation, and slot opening and closing. A major contribution of this work is the quantification of the performance and limitations of the DFOS system under large cyclic strains. Performance is quantified in terms of non-valid points (which occur in large strains when the DFOS analyzer does not return a strain value), maximum strain that can be reliably measured, crack width that causes cable rupture, and the effect of the cable coating on the measurements. Structural damage indices are also proposed based on the DFOS results. These damage indices correlate reasonably well with the maximum sustained drift, indicating the potential of using DFOS for RC structural damage assessment. The experimental data set is made publicly available.

This study investigates the flexural deformations of buildings induced by mining-related subsidence. A two-stage solution (previously applied to the tunnelling problem) is used. Buildings are modelled as a beam founded on an elastic continuum that is subjected to ground subsidence. A tensionless soil-structure interface is employed. The effects of both building stiffness and self-weight on the building deflection are considered. The proposed formulation is compared with analytical solutions and empirical envelopes from previous research. A parametric study is conducted for both perfect soil-foundation bond and gap formation to relate deflection ratio modification factors and the limit radius of the greenfield settlement curve (associated with the gap formation) to relative structure-soil stiffness, building weight, foundation shape, and greenfield ground curvature (hogging or sagging) by means of dimensionless groups. Finally, a simple case study is used to demonstrate the proposed procedure. The given framework is more comprehensive than design charts provided by previous mining-related works and can be used for rapid preliminary risk assessment. Key words: mining subsidence, settlements, soil-structure interaction, building response. La presente etude porte sur les distorsions en flexion des batiments causees par les affaissements lies a l'exploitation miniere. On a recours a une solution en deux etapes (precedemment appliquee au probleme du creusement de tunnels). La construction est modelee comme une poutre fondee sur un continuum elastique qui est soumis a l'affaissement du sol. Pour cela, on utilise une interface sol-structure sans tension. On examine les effets de la rigidite et de l'auto-poids de la construction sur la deflexion de la structure. Enfin, la formule envisagee est comparee a des solutions analytiques et a des enveloppes empiriques provenant de recherches precedentes. Les facteurs de modification du taux de deflexion et le rayon limite de la courbe de tassement du sol (associe a la formation de l'espace) sont mis en relation avec la rigidite relative de la structure du sol, le poids du batiment, la forme de la fondation et la courbure du sol (affaissement ou affaissement) au moyen de groupes sans dimension. Pour conclure, la procedure proposee est illustree par une simple etude de cas. La structure donnee est plus detaillee que les diagrammes de conception obtenus lors de travaux anterieurs lies a l'exploitation miniere et peut servir a une evaluation preliminaire rapide des risques. Mots-cles : affaissement minier, implantations, interaction sol-structure, reponse la construction., 1. Introduction Many urban areas are at risk of mining subsidence caused by normal mining operations (Kratzsch 1983; Whittaker and Reddish 1989; Donnelly et al. 2001; Can et al. 2012; [...]

Spaceborne multi-temporal interferometric synthetic aperture radar (MT-InSAR) is a monitoring technique capable of extracting line of sight (LOS) cumulative surface displacement measurements with millimeter accuracy. Several improvements in the techniques and datasets quality led to more effective, near real time assessment and response, and a greater ability of constraining dynamically changing physical processes. Using examples of the COSMO-SkyMed (CSK) system, we present a methodology that bridges the gaps between MT-InSAR and the relative stiffness method for tunnel-induced subsidence damage assessment. The results allow quantification of the effect of the building on the settlement profile. As expected the greenfield deformation assessment tends to provide a conservative estimate in the majority of cases (~71% of the analyzed buildings), overestimating tensile strains up to 50%. With this work we show how these two techniques in the field of remote sensing and structural engineering can be synergistically used to complement and replace the traditional ground based analysis by providing an extended coverage and a temporally dense set of data. [ABSTRACT FROM AUTHOR]