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Computer vision enables a much more efficient monitoring system of structural behavior, compared to traditional methods. This derives from the fact that it allows the assessment of displacements in a vast number of points that can be processed to the estimate deformations, accelerations, and other key parameters at relevant cross‐sections. This paper proposes a computer vision‐based methodology, specifically designed for monitoring seismic tests conducted on a shaking table with a reduced‐scale model, using a single camera approach. This innovative methodology uses artificial targets with predefined color and geometry to optimize their detection and tracking. These targets are positioned at key points of the reduced model—“Moving Targets”—and at reference points of the seismic table—“Control Targets.” Videos are recorded during the seismic tests and the coordinates (in pixels) of the targets' centers are automatically detected and captured. Then, transformations are applied to each frame to compute the targets coordinates in millimeters and based on the differences between frames, to calculate the displacements of each target. The methodology was first calibrated with dynamic tests performed on a reduced‐scale model (1:33) of a prefabricated concrete shell, printed in acrylonitrile butadiene styrene (ABS), conducted on an educational shaking table. Afterwards, the methodology was validated with seismic tests performed on a 1:3 reduced model of a prefabricated concrete shell, produced according to the similitude theory to best reproduce the behavior of the corresponding prototype. It was demonstrated the ability of the methodology to monitoring seismic tests, enabling continuous tracking of the targets placed on a structure with complex geometry. [ABSTRACT FROM AUTHOR]

The prediction of the structural behavior and the internal forces acting in segmental tunnel linings is a difficult task and contains uncertainties. In situ measurements within structural monitoring are the only possibility to assess the results under realistic boundary conditions. However, no standardized structural monitoring method for segmented lining exists and consequentially setting up a new monitoring project requires an increased effort. Therefore, in this paper, first, an analysis of experiences in reported monitoring projects is done. Then, a report on a current monitoring project carried out by the authors and the experiences made are presented. Based on these, suggestions are given to facilitate future applications of structural monitoring on segmental tunnel linings regarding conceptualization, instrumentation, installation, operation, and data evaluation. [ABSTRACT FROM AUTHOR]

Structural monitoring strategies contributing to a realistic assessment and surveillance of engineering structures – experiences from research and practice Structural monitoring allows for capturing the actual load‐bearing behavior of engineering structures and their realistic assessment and surveillance. Various technical and organizational aspects must be considered for a successful application of structural monitoring. These include the preparation and conceptual design of the monitoring, the calibration and validation of the measurements, the installation and operation of the measurement system, as well as the data evaluation and analysis. These aspects will be discussed based on experiences from research and practice, and consequential recommendations will be given. The application possibilities of structural monitoring are presented with four examples. [ABSTRACT FROM AUTHOR]

Structural Monitoring in Civil Engineering – The new guideline B 09 of the German Society for Non‐Destructive Testing (DGZfP) Measurement systems for structural monitoring provide insights into their real load‐bearing and deformation behavior. The planning and technical implementation of such measures require a high level of expertise for the successful fulfillment of the tasks, both on the planning side and for the technical evaluation of the monitoring solutions offered. The German Society for Non‐Destructive Testing (DGZfP) has developed the Code of Practice "Monitoring of Civil Engineering Structures" to assist in this process. In this article, the contents of the new bulletin is presented and its place in the context of the existing literature demonstrated. [ABSTRACT FROM AUTHOR]

New BAW bulletin on structure monitoring – sustainable infrastructure management on federal waterways The introduction of the new administrative regulation VV‐WSV 2101 Inspection of Structures adjusts inspection regime of federal waterways be more finely. Structures that have recently been classified in Inspection Category B do in principle have a special hazard potential with regard to the traffic safety to be ensured, but they are not so complex from a structural engineering point of view that they require – in contrast to Inspection Category A – a structural inspection by expert engineers. In this case, structural monitoring will be required in the future. The associated, newly developed BAW bulletin Damage Assessment on Waterway Structures of Inspection Category B (MSV‐B) groups the structures under consideration and provides guidelines for the systematic recording and assessment of damage to them. With the help of extensive standardization, the bulletin meets the requirements for efficient data collection on site as well as for the documentation of the results in the WSVPruf software for maintenance management. After closely concerted development and elaboration in 2021, quality assurance distributed within the administration, and widely distributed training by means of digital e‐learning formats, the bulletin was introduced in March 2022. [ABSTRACT FROM AUTHOR]

Summary: This study presents a designed framework of structural monitoring for coupled shear wall structures by integrating a theoretical response estimation model and a prototype micro‐voltage sensing module. Inspired by the deformation mode of coupled shear walls, a supplemental self‐sensing component is proposed for predicting the target flexural deformation. The self‐sensing component is designed to include permanent magnets and cross wires and installed parallel to the coupling beam. The relative velocity between the two attached walls is obtained using electromagnetic (EM) induction and measured micro‐voltages. Accordingly, the theoretical principle of the self‐sensing prediction model is then derived, and the calculation flowchart is presented. Illustratively, a detailed finite element model was performed in ABAQUS to investigate the feasibility and robustness of the proposed self‐sensing model under different excitation scenarios, and a parametric study is performed. Then, the nonstationary excitation is adopted to further investigate the performance of the self‐sensing model. Furthermore, an EM‐based sensing module for low‐level velocity measurement is developed and the prototype is tested by utilizing a shaking table test with satisfactory performance. [ABSTRACT FROM AUTHOR]

Aggregation of condition indicators for bridge structures based on inspection and monitoring data In Germany, the assessment of existing structures is based on a uniform structural rating obtained from regular in situ inspections. However, a method to include monitoring data into the structural rating does not yet exist. Though, a structural monitoring can be used to monitor the occurrence or the growth of damages, thereby reducing the risks emanating from theses damages. Furthermore, calculative safety deficits can, in many cases, be compensated by specific monitoring measures. Challenges concerning the integral assessment result from the differences in the assessment of structural damages (rating) and limit state checks (utilization). This paper presents a method which aggregates monitoring data and structural damages into a real time condition indicator that is also comprehensible for non‐experts. Apart from the general rating procedure that includes well‐known elements of the rating system of the German structural information database "SIB‐Bauwerke", two use cases of the smartBRIDGE concept for the Köhlbrandbrücke in Hamburg will be shown. The use cases consist of two current calculative safety deficits which are compensated by monitoring measures. [ABSTRACT FROM AUTHOR]

Location‐specific target load level and object‐specific load models for recalculation based on structural monitoring When evaluating existing bridges, supporting structural monitoring is increasingly being used in order to obtain the stresses in the structure more realistically than purely mathematically and to calibrate the calculation model. The question of how the additional informations obtained through measurements have to be taken into account within the recalculation, including its safety concept, is currently still normatively unclear. On the load side, this can be done through the modified definition of the target load level or, alternatively, through object‐specific load models for load‐bearing capacity and fatigue to map the actual traffic. Furthermore, on the basis of the measurement data, the necessary safety factors can be justified, also taking into account future traffic developments, while maintaining the normatively required level of reliability. [ABSTRACT FROM AUTHOR]

Smartphone‐based vibration measurement for the assessment of bridge structures In order to ensure permanent and accurate monitoring of engineering structures, an area‐covering monitoring system is desirable. In this article, it is investigated whether the sensors of smartphones and tablets (SPT) are sufficient for vibration measurement. Evaluation in terms of system parameters such as natural frequencies and damping coefficients is also considered. With the help of tests under laboratory conditions on a single‐span beam and tests in the field on a test bridge on the premises of the University of the German Armed Forces, the application suitability of smartphones and tablets is considered. In addition to the measurements with SPT, reference measurements were carried out with a classical vibration measurement system. The signals and their evaluation are compared with each other and, in the case of the laboratory test on the single‐field beam, with model values of an SDOF single‐mass vibrator. This demonstrates the principle application of the SPT, as well as the suitability of the recorded signals for further processing for system identification. [ABSTRACT FROM AUTHOR]

Structural reliability assessment by structural monitoring – probabilistic buckling check of the Hamburg Köhlbrand bridge The bad condition of many older bridges and changes in the code provisions often result in deficits after recalculation according to the recalculation guidelines. In case the necessary structural safety is not provided, temporary or permanent structural monitoring can be employed in order to gain knowledge about the time variant actions. For this, the derivation of condition indicators is key, since they indicate a need for action for the owners and the engineers. In the simplest case, a utilization will be derived which, however, does not allow for an assessment of the risk and strictly speaking only enables a binary assessment. In this paper, a method is described and demonstrated on the Hamburg Köhlbrand bridge which allows for the calculation of a reliability index as a time variant condition indicator on the basis of the dynamic monitoring data with regard to the buckling check. [ABSTRACT FROM AUTHOR]

Dynamic loads reduce the load bearing capacity and the service life of structural components and constructions. This article discusses fatigue stresses and their effects on uncracked concrete structures using the example of concrete bridges. In standard proofs, a distinction is made between the stresses on and the resistance of structural components. Thus, first the determination of the damage‐equivalent stresses on constructions will be considered. Subsequently, the resistance of construction materials, structural components, and the whole construction has to be determined. Based on these input data for the verification, the load bearing capacity and service life under fatigue loading shall be assessed. [ABSTRACT FROM AUTHOR]

Realistic traffic load models for reassessment of Gänstor Bridge over the Danube The Gänstor Bridge over the Danube erected in 1950 is a historical bridge structure, connecting the two cities of Ulm and Neu‐Ulm. Due to increasingly occurring deficiencies and damages on the structure throughout its previous service life, extensive measures regarding structural reassessment and evaluation have been initiated. An object specific evaluation of traffic load models serves as an important element in this concept. For this purpose, realistic modelling of the actual traffic load demands is performed by means of precise object reference regarding traffic and structure. Monitoring of local traffic on the bridge to analyze local traffic characteristics has been performed. The findings serve as input for numerical simulations performed subsequently to model traffic loading on the bridge for different scenarios of traffic routing. Results from these simulations allow for an evaluation of actual traffic loading, and hence a validation of load models considered in bridge reassessment. Additional verification of results is obtained by comparison with simultaneously detected and belatedly provided monitoring data from strain gauges applied to some of the tendons of the structure. [ABSTRACT FROM AUTHOR]

Concepts for the assessment of bridges with the risk of stress corrosion cracking The networks of the road construction authorities and DB AG still contain a significant number of bridges manufactured with steel endangered by stress corrosion cracking. Although there are guidelines that provide computational and material assessment, they do not always lead to a (desired) result and the final definition of appropriate measures. In this context permanent monitoring has played a subordinate role, even though the degradation processes and their consequences occurring in the structure can be excellently resolved and the continuous information gives the possibility to state the condition of the structure at any time. The present article composes the existing rules and shows the possibilities and limitations of the recommended methods. Subsequently, examples for the implementation of monitoring systems are presented each for a building with and without computational announcement before collapse. [ABSTRACT FROM AUTHOR]

Summary: Recurring expenses associated with preventative maintenance and inspection produce operational inefficiencies and unnecessary spending. Human inspectors may submit inaccurate damage assessments and physically inaccessible locations, like underground mining structures, and pose additional logistical challenges. Automated systems and computer vision can significantly reduce these challenges and streamline preventative maintenance and inspection. The authors propose a convolutional neural network (CNN)‐based approach to identify the presence and type of structural damage. CNN is a deep feed‐forward artificial neural network that utilizes learnable convolutional filters to identify distinguishing patterns present in images. CNN is invariant to image scale, location, and noise, which makes it robust to classify damage of different sizes or shapes. The proposed approach is validated with synthetic data of a composite sandwich panel with debonding damage, and crack damage recognition is demonstrated on real concrete bridge crack images. CNN outperforms several other machine learning algorithms in completing the same task. The authors conclude that CNN is an effective tool for the detection and type identification of damage. [ABSTRACT FROM AUTHOR]

Numerous different techniques and instruments can be used for structural monitoring with different requirements producing different results. For instance, some techniques need to use embedded sensors inside the building, such as geotechnical sensors. However, this method cannot be used for historic and heritage buildings. Other methods can offer high quality, but with a low point density and require fixed stations and targets, such as total stations. In such a case, the location of deformation tends to be known, such as dams, bridges, high-rise buildings, and so forth. Nevertheless, this is not the case for historic and heritage buildings where each block could be subject to deformation. The challenge in such a case is to detect the deformation without any previous knowledge. The aim of this research is to develop a new approach to detect and localise unpredictable deformation. It is based on terrestrial laser scanner measurements and generalised Procrustes analysis techniques to determine deformation vectors, although boxing structure and F-tests are used to detect and localise deformation. In summary, after applying this approach, the whole concerned building is represented as parts, for each of them, the displacement vector and deformation probability are estimated. Validation experiments have shown the capability of the proposed method to detect and localise deformation with magnitude less than noise level in simulated data and of subcentimetre level for ranges up to 10 m in real scan data. Finally, the new approach has been applied to an English Historic site, Bellmanpark Limeklins. [ABSTRACT FROM AUTHOR]

Design errors, misuse, and natural or accidental events can cause small and cumulative damages or large and sudden damages that can deteriorate structural systems or cause their collapse. Structural monitoring consists in the permanent real-time tracking of information about the condition and performance of a structure. This paper presents the development, validation, and implementation of the structural monitoring system for building 350 at Del Valle University, located in Santiago de Cali, Colombia. The system uses the SSI and natural excitation technique with the eigensystem realization algorithm methodologies for modal identification and a specialized event-recognition algorithm based on the standard deviation analysis of vibrations. The dynamic behavior monitoring of the building has been conducted in real-time since January 2012, and six seismic events have been successfully recognized. The computational tool was validated using a finite element model with which the effect of variation in mass was evaluated. [ABSTRACT FROM AUTHOR]

In this paper, an integrated distributed fiber optic sensing technology, which includes Raman optical time-domain reflectometry (ROTDR), Brillouin optical time-domain analysis (BOTDA), and fiber Bragg grating (FBG) sensing technologies, is adopted to monitor the temperature and the stress/strain variations of a reinforced concrete pound lock structure during the construction process. The Raman optical time-domain reflectometry was used to monitor the internal temperature variation throughout the concrete curing process when concrete hydration heat was released in the base plate of the lock head. The FBG temperature sensors were adopted to measure the surface temperature of the concrete, and the temperature data were used to compensate the results that are measured by BOTDA sensing technology to get the real concrete strain of the base plate. To better understand the stress/strain state of the base plate before and after filling water in the lock, the BOTDA sensing cable and FBG temperature sensors monitoring continued throughout the whole construction process. The observation provided a positive indication that the proposed integrated distributed fiber optic sensing technology may have great potential in performance monitoring of hydraulic structures. [ABSTRACT FROM AUTHOR]

The research focuses on structural monitoring and movements identification applied to cultural heritage protection. The final purpose is the integration among different and independent technologies for analyzing and investigating the geometry changing over time of ancient leaning towers. The paper deals with a novel strategy implemented to compute differential vertical displacements starting from results obtained by repeated high-precision leveling network adjustments. These results usually aim at monitoring the subsidence phenomenon, while their use in engineering applications is more or less absent in literature. Moreover, the multidisciplinary approach is also able to analyze subsidence gradients in order to extrapolate the trend of the vertical axis and compute structure's rotations. The approach is applied to the Ghirlandina Tower, Modena (Italy), in order to identify the leaning and the subsidence trend. About 30 years of leveling campaigns provide a useful dataset to test the methodology, which is finally validated by the independent observations collected by a pendulum. The approach allows to compute the mean total displacement since 1984 of about 4.7 cm with 30% occurring over the last 6 years. In the same period, the total overhang of the tower (1.30 m in 2007) increased by about 19.1 and 10.4 mm towards southwest. The approach is also able to identify anomalous behavior of the tower such as the reversal tilting trend due to the scaffolding in the years of restoration and the permanent deformation suffered after the 2012 Emilia Romagna earthquake (failure of 4 mm in 6 months). Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

SUMMARY The recently developed precise point positioning (PPP) technique permits to compute instantaneous coordinates of a GPS station relatively to distant reference stations and waveforms of ground displacements during strong motions at the 1 Hz level. This is another application of GPS, different from the computation of static coseismic movements or of accurate monitoring of dynamic displacements of structures using a static receiver and a nearby moving receiver (DGPS). Recently, earthquake ground displacement waveforms using 10-Hz GPS data have also been calculated, but no independent evidence to assess their quality exists. To overcome this problem, we evaluated the output of 10-Hz PPP results on the basis of supervised learning experiments. Semistatic and dynamic displacements (damped harmonic oscillations) of known characteristics of the order of a few centimeter were produced and were recorded by GPS, an accelerometer, and a robotic total station. Time series of instantaneous displacements were analyzed using different PPP techniques and were compared with reference (true) values derived from DGPS and the other sensors. Our analysis revealed that the PPP-derived coordinates are contaminated by long-period noise but they can display the details of semistatic displacements, while their short-period component describes well the pattern of waveforms and spectra (at least up to 4 Hz) of dynamic displacements, with up to 20 mm accuracy for isolated points. These results indicate that 10-Hz PPP-GPS is useful for earthquake engineering and can safely be used to reconstruct waveforms of deflections of the ground and of various points on structures during strong motions. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Structural monitoring and structural health monitoring could take advantage from different devices to record the static or dynamic response of a structure. A positioning system provides displacement information on the location of moving objects, which is assumed to be the basic support to calibrate any structural mechanics model. The global positioning system could provide satisfactory accuracy in absolute displacement measurements. But the requirements of an open area position for the antennas and a roofed room for its data storage and power supply limit its flexibility and its applications. Several efforts are done to extend its field of application. The alternative is local positioning system. Non-contact sensors can be easily installed on existing infrastructure in different locations without changing their properties: several technological approaches have been exploited: laser-based, radar-based, vision-based, etc. In this paper, a number of existing options, together with their performances, are reviewed. [ABSTRACT FROM AUTHOR]

ABSTRACT Structural health monitoring systems are conceived to automatically monitor the structural health state in real-time. The high-cost and the labor intensive installation of wired monitoring system suggest that structural monitoring systems be realized of a wireless nature. This study explores the development of a general and high-performance wireless data acquisition system (WDAQS) specifically designed for sensors commonly adopted in structural health monitoring applications. When compared with wired sensor technology, wireless sensor technology suffers limited energy supply, long data collection delay, big noise floor, and data loss. Addressing these issues, in the design of the WDAQS, several features are pursued, including flexible sensor interfaces, high power efficiency, low-noise data acquisition, and real-time and lossless data transmissions. The design of the system is presented in detail in terms of hardware, firmware, and software. Several experiments are carried out to validate and evaluate the system. The results show that the WDAQS is able to acquire high-quality data. Copyright © 2013 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

SUMMARY Damping ratio is an important component in the dynamic analysis and plays a key role in design of supertall buildings. It is necessary to have reliable field measurement records for estimation of structural dynamic characteristics. The main objective of this paper is to estimate eigen mode damping ratio of TV towers as a kind of supertall buildings with the height of more than 250 m. In this regard, field measurements were performed on Milad TV tower, located in Tehran, which has a height of 435 m by ambient vibration monitoring. Damping ratio of this tower is determined using random decrement technique and compared with available data of a few other TV towers. For proposing eigen mode damping ratio of TV towers, it is shown that Rayleigh damping coefficients could not be calibrated properly for tall slender TV towers. A damping estimation chart of TV tower that is a function of natural frequency and structural aspect ratio is proposed, and the chart validity has been checked with field measurement results of other TV towers. The chart shows that structural damping for wind analysis proposed in design codes and standards is overestimated for tall slender TV towers. Copyright © 2011 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Die Nutzungsdauer bestehender Brückenbauwerke wird neben Korrosionseinflüssen hauptsächlich durch die vorangegangenen, die gegenwärtigen sowie durch die prognostizierten ermüdungsrelevanten Beanspruchungen bestimmt. Diese resultieren in erster Linie aus den verkehrenden Schwerlastfahrzeugen. Voraussetzung, um Aussagen über die Zuverlässigkeit und Dauerhaftigkeit von Straßenbrücken treffen zu können, ist die realistische Abbildung der Einwirkungen aus dem Schwerverkehr. Informationen zur Schwerverkehrszusammensetzung, dem durchschnittlich täglichen Schwerverkehrsaufkommen sowie zu den Achs- und Fahrzeuggesamtgewichten können für einen festgelegten Standort mithilfe von Weigh-In-Motion-Systemen ermittelt werden. Ein solches System, bestehend aus optischen und taktilen Messeinrichtungen, wurde an den Überbauten sowie an den Fahrbahnübergangskonstruktionen von zwei Bestandsbauwerken realisiert. An Auszügen aus den Mess- und Auswerteergebnissen wird dargestellt, dass der aktuelle Verkehr auch auf diese Weise quantifiziert werden kann. Identification of traffic loads by measurements at expansion joints The service life of existing bridges depends on the previous, present and predicted fatigue stresses. These are primarily caused by passing heavy gross vehicles. Prerequisite for statements about the reliability and durability are realistic load models of heavy traffic. Information about the heavy traffic conditions, the average daily traffic volume and the axle loads and gross vehicle weights of the heavy gross vehicles can be determined by Weigh-In-Motion systems. Such a system consisting of optical and tactile measuring devices has been realized at the superstructure and the expansion joint of two existing bridge structures. Extracts of the measurement and evaluation results will be presented to show that current traffic loads can also be quantified in this manner. [ABSTRACT FROM AUTHOR]

SUMMARY The full-field reconstruction method presented here is suitable for real-time structural monitoring purposes, such as improving the performances of structures. The aim is to characterize mechanical fields and boundary conditions while the structure is in service, using just a few on-line measurements. This characterization is an ill-posed inverse problem, the solution of which requires making some prior assumptions. The structures studied are assumed to be in steady-state configurations and to show linear mechanical behavior, and the loading zones are assumed not to be overstressed; the mechanical fields are monitored only inside the structures. The full-field identification is regularized using the boundary conditions, which are identified from strain measurements, and the mechanical fields are then reconstructed from these identified boundary conditions. On the basis of Saint-Venant's principle, the boundary conditions are approximated with a few parameters, the basis functions of which are obtained from the projections of Trefftz-like solutions onto the boundaries of the structures. These approximate boundary conditions are linked to the global mechanical responses of the structures. Lastly, this full-field reconstruction method is applied to plate-like structures with holes subjected to in-plane loads. The results show that the load identification procedure efficiently regularizes the full-field reconstruction method, and that this method is suitable for structural monitoring purposes. The sensitivity of this method to errors is similar to that of the load identification procedure, and the maximum errors in the solutions are located at the boundaries. Copyright © 2012 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

In the cultural heritage field, the monitoring of the integrity of structures can greatly benefit from 3D digitising techniques. The aim of deformation analysis and structural surveillance is the early detection of damage in order to be able to react appropriately and in good time. The devices that have been traditionally used in the measurement of fissures, cracks and fractures are contact tools whose application depends on accessibility; moreover, they only provide discrete point measurements rather than giving a continuous record of the damage dimension in the whole affected area, as modern 3D modelling techniques can do. Among these techniques, close range photogrammetry is still the most complete, economical, portable, flexible and widely used approach in architectural applications. This paper is focused on the application of close range photogrammetry in the detection and monitoring of structural damage. The following procedure is proposed: the gathering at different epochs of 3D point clouds in the neighbourhood of cracks; the comparison among the successive point clouds by means of shape parameters; and the application of a bootstrap test for the detection of the significant statistical results. This procedure is applied to the analysis of structural damage detected in a masonry structure of cultural heritage interest: Basílica da Ascensión, located in the north-west of Spain. [ABSTRACT FROM AUTHOR]

Summary: The increasing demand for underground infrastructure should be supported by innovation in monitoring and damage assessment solutions to minimise damage to surface structures caused by ground settlements. This paper evaluates the use of multitemporal synthetic aperture radar interferometry (MT‐InSAR) to calculate tunnelling‐induced deformations of buildings. The paper introduces a step‐by‐step procedure to use InSAR displacements as an input to the structural damage assessment. After a comparison between traditional and InSAR monitoring data for the London area during the Crossrail excavation, the high resolution, high density InSAR‐based displacements were used to evaluate the building deformations for a number of case studies. Results demonstrate the quality of information provided by InSAR data on soil‐structure interaction mechanisms. Such information, essential to evaluate current damage assessment procedures, is typically only collected for relatively few buildings due to the cost of traditional monitoring. A comparison between damage indicators derived from greenfield assumptions and building displacements quantifies the practical benefit of the proposed step‐by‐step procedure. This work aims at filling the gap between the most recent advances in remote sensing and the civil engineering practice, defining the first step of an automated damage assessment procedure which can impact large scale underground projects in urban areas. [ABSTRACT FROM AUTHOR]