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Pre-stressed concrete with post-tensioned (PT) cables historically represented an attractive alternative to ordinary reinforced concrete (RC). A wide portion of the world-wide existing concrete bridges was PT. As the nominal service life of those structures expires, several collapses occurred, highlighting the problem of the inspection. The main issue is that PT cables may be affected by relevant corrosion phenomena related to the presence of air or water inside the duets: such 'hidden' defects need to be determined through reliable testing methodologies. This paper presents the in-progress research aiming to quantify the influence of the damage of the single cable on the entire structure. The case study is an ltalian viaduct composed of simply supported beams connected by an upper slab. An extensive investigation campaign was carried out to locate and quantify the damage. Starting from the data collected on-site a series of damage conditions of cables can be simulated.

This deliverable presents a report of the needs for structural control on buildings (initial imperfections, deflections at service, stability, rheology) and on bridges (vibrations, modal shapes, deflections, stresses) based on state-of-the-art image-based and sensor-based techniques. To this end, the deliverable identifies and describes strategies that encompass state-of-the-art instrumentation and control for infrastructures (SHM technologies). Objectius de Desenvolupament Sostenible::8 - Treball Decent i Creixement Econòmic Objectius de Desenvolupament Sostenible::9 - Indústria, Innovació i Infraestructura

Despite their advantageous performance and reliability, distributed optical fiber sensors (DOFS) still constitute a recent technology and their reliability and accuracy when applied to real world structures is still under probation since there is still room for improvement and for widening their applicability. In general, standardized guidelines need to be developed to ensure success in every DOFSs deployment regarding fiber bonding to the structure, temperature affections on readings, postprocessing of reading anomalies, among other factors. However, real applications, as in the one presented in this paper, show that DOFS are anticipated to have a very important role in Structural Health Management of tunnels in the near future if correctly understood and developed. This paper addresses the implementation of a Distributed Optical Fiber Sensor system (DOFS) to the existing TMB L-9 metro tunnel in Barcelona for Structural Health Monitoring (SHM) purposes as the former could potentially be affected by the construction of a nearby residential building. The results show a good performance of this novel technique in the monitoring of strain along the whole affected sections during the construction of a nearby building. In fact, the DOFS readings reproduce very accurately the tunnel deformation process. The tendencies observed by the sensors were forecasted by a simple theoretical model. The monitoring of the strain at many points in the critical section allowed to conclude that the nearby construction only slightly affected the lining stresses and that safety was guaranteed during the whole monitored period. The authors thank COTCA and TMB respectively for providing access to the necessary data regarding the case study and supporting this research. We would also like to thank Ph D student Mattia F. Bado who provided insight that greatly assisted this research during the data post-processing phase. The authors are indebted to the Spanish Ministry of Economy and Competitiveness for the funding provided through the research project BIA2017-86811-C2-1-R. All these projects are funded with FEDER funds. Authors are also indebted to the Secretaria d’ Universitats i Recerca de la Generalitat de Catalunya for the funding provided through Agaur (2017 SGR 1481).

Structural Health Monitoring (SHM) in bridges is an important field, which implements increasingly innovative damage detection strategies for both theoretical developments and laboratory-scale implementations. However, is very important to consider the studies of bridges in real conditions. This study presents the damage identification of a real bridge using Hilbert-Huang transform and the most recent advance in the empirical mode decomposition method (EMD) called Improvements on Complete Ensemble Empirical Mode Decomposition with Adaptive Noise (ICEEMDAN). This technique is used to decompose vibration data into intrinsic mode functions (IMF). Then, the Marginal Hilbert spectrum and phase difference were two damage features studied on a bridge where artificial damage was imposed. These artificial damage levels were applied sequentially and the vibration data was obtained by the passage of a recreation vehicle. As results, the ICEEMDAN method and proposed damage indicators demonstrate good performance to detect and locate damages under transient vibration loads on a real bridge. The first author acknowledges the support received from Ministry of Education of Peru with the National Scholarship and Educational Loan Program PRONABEC - President of the Republic Scholarship. The authors wish to express their gratitude to professor Woo Kim of the Department of Civil and Earth Resources Engineering, Kyoto University, Kyoto, Japan for the generous sharing of the steel truss bridge data assessed within this study.

Structural Health Monitoring (SHM) systems have been heavily studied worldwide in the past decades. In this field, extensive research has been carried out on vibration-based damage detection (VBDD) techniques in civil structures, especially in bridges. Dynamic responses of a structure manifest a certain degree of sensitivity not only to structural damage but also to any change in operational and environmental conditions, these last factors can mask structural damages. In this sense, the main objective of this paper is to separate structural damage conditions from the changes caused by the environmental effects in a numerical benchmark bridge structure. Temperature is chosen as a global environmental parameter for its significant impact on the waveform, and the Instantaneous Phase Difference (IPD) obtained from an analysis of the Hilbert spectral is studied as the vibration damage feature. Principal Component Analysis (PCA) is applied mainly to the IPD in order to eliminate the environmental influence. Due to the lack of experimental data including the temperature effects, the effectiveness and robustness of the proposed procedure is applied to a numerical benchmark bridge structure generated as part of COST Action TU1402 on quantifying the value of information (VoI) in SHM. The benchmark model consisted of a two-span steel bridge under operational (vehicular traffic) and environmental variability, in which two levels of damage were introduced. The dynamic responses in both healthy and structural damage conditions were obtained from a nonlinear time-history analysis using an open access Python code. As the main concluding remark, the suitability of Hilbert-Huang Transform combined with a PCA-based approach and the instantaneous phase difference to achieve a more robust damage assessment algorithm is verified for the numerical benchmark bridge. The second author wishes to express their gratitude for the financial support received from PRONABEC Program of Peruvian Ministry of Education with the President of the Republic Scholarship for the great support on his PhD studies. The authors wish to thank the Prof. Eleni Chatzi, ETH Zurich, for their valuable sharing of the entire data from numerical benchmark bridge used in the present research. Authors are indebted to the Secretaria d’ Universitats i Recerca de la Generalitat de Catalunya for the funding provided through AGAUR (2017 SGR 1481).

Structural health monitoring (SHM) is being widely used for the safety assessment and management of existing bridges and structures. One of the objectives related to SHM is to maximize the information gained from the structural testing, while keeping the number of sensors and consequently the cost of the sensor system to a minimum. The current work investigates four of the most influential optimal sensor placement (OSP) methods: the modal kinetic energy (MKE) method, the effective independence (EFI) method, the information entropy index (IEI) method and the MinMAC method. The methods were developed in MATLAB and used as input data the modal analysis results of a finite element model built in ANSYS of the Streicker Bridge, a pedestrian bridge located on the Princeton University Campus. The resulting sensor positions were estimated for a configuration with 14 sensors, and the four OSP methods were evaluated for different numbers of target sensors in terms of different OSP criteria: the determinant (DET) of the Fisher information matrix, the information entropy index (IEI) and the root mean square (RMS) of the off-diagonal entries of the MAC matrix. The study indicates that the EFI method should be chosen to estimate the optimal sensor positions as it provides the largest amount of information with a relatively low computation time. The authors are indebted to the Spanish Ministry of Economy and Competitiveness for the funding provided through the research project BIA2017-86811-C2-1-R. All these projects are funded with FEDER funds. Authors are also indebted to the Secretaria d’ Universitats i Recerca de la Generalitat de Catalunya for the funding provided through Agaur (2017 SGR 1481).

The damage identification process through Structural Health Monitoring (SHM) field has drawn extensive attention over the last decades for its numerous applications in failure prevention and maintenance decision-making. Several research in vibration-based methods for SHM have shown that a potential structural damage can be inferred from a change in the dynamic response of the structure. The aim of this paper is to detect and locate different damage scenarios in a benchmark bridge structure under a moving load based on Hilbert-Huang Transform (HHT). The data used in this study was obtained from the TU1402 benchmark towards enhancement of the value of SHM. The benchmark model consisted of a two-span steel bridge, where six levels of damage grouped in two damage region cases were introduced. In the proposed damage detection method, the transient vibration signals coming from a moving load in the bridge, are firstly decomposed into intrinsic mode functions (IMFs) using the Variational Mode Decomposition (VMD) approach. Then, the Hilbert Transform (HT) is applied to the IMFs. Lastly, the Marginal Hilbert Spectrum (MHS) and the Instantaneous Phase Difference (IPD) were used as damage indicators by comparing the undamaged condition of the bridge with each damage scenario. Results demonstrated that the proposed damage indicators were accurate for identifying and locating damage under transient vibration loads. The second author acknowledges the financial support provided by the Government of Peru through the Educational Credit Program PRONABEC, as well as his Ph.D. Scholarship. The authors are grateful to Prof. Eleni Chatzi, ETH Zurich, Switzerland for the valuable numerical benchmark data assessed within this study. Authors are indebted to the Secretaria d’ Universitats i Recerca de la Generalitat de Catalunya for the funding provided through AGAUR (2017 SGR 1481).

This paper outlines the principal results of laboratory and field testing in concrete structures to show the capabilities of distributed optical fiber sensors (DOFS) in their application to monitoring concrete structures. In the first part of this paper, a methodology to obtain the mean shear crack width in concrete beams is proposed. This methodology is based on the laboratory experimental data obtained by a DOFS bonded to the surface of two pre-stressed partial concrete (PPC) beams subjected to shear test with increasing levels of load. The results show the feasibility of the proposed method in calculating the shear crack width when compared to the results from traditional instrumentation. In the second part of the paper, a monitoring process by DOFS on a real world structure is described. The principal results of the enlargement of a pre-stressed concrete bridge are presented. The versatility and easy installation of DOFS compared with traditional monitoring systems is an important characteristic to consider in its application when monitoring real world structures. The DOFS used in this study provide continuous (in space) strain data along the optical fiber with high spatial resolution in the order of millimeters. This study verifies that the OBR technique is applicable in real conditions and confirms the high accuracy inherent to the optical fiber technology. The use of the OBR technique is not only able to detect appearing cracks, but also to perform a global structural behavior monitoring. For this reason, this technique is an important alternative to cover the limitations (number of points interrogated) of the discrete sensors such as strain gauges or LVDT´s, with which only local data is obtained.

Nowadays, seismic study of corroded reinforced concrete elements is a matter of increasing concern, in particular for links such as bridges in infrastructural networks. In a starting step of an ongoing research, a bridge overpass was selected to perform seismic analyses. It allowed to assess the degrading seismic capacity of the bridge pier at different ages because of the reduction of the cross-section of the rebars due to general and pitting corrosion. An uncontrolled factor of the previous study is that corrosion can also affect bonding, thus increasingly reducing ductility and safety performance. However, in a corroded structure bond strength and confinement capacity can also decrease due to the transverse reinforcement area loss, and concrete cover cracking and spalling. This new step is focusing on bonding failure effects in bridge corrosion processes and the preliminary results will be presented.

Damage caused in bridges can be hidden by the service conditions mainly due to environment effects as temperature and traffic loading. The literature review indicates that the majority of investigations are limited since they do not consider these effects or they are applied under laboratory conditions and not to real bridges. The temperature effects on the natural frequencies of bridges have shown to be non-linear. In this context, this article presents a damage detection strategy considering a more robust kernel-based method (KPCA) which is the nonlinear extension of the principal component analysis (PCA) to take into account the environmental conditions of the bridge such as the non-linearity of the temperature effects in the natural frequencies. This method is combined with a clustering analysis in order to group the data with similar features both for undamaged and damaged conditions, and in this way the structural damages can be identified. The main contribution is a novel damage detection methodology based on advance statistical and machine learning algorithms to account for the non-linear environmental effects. The method is checked using measurements from the Z24 bridge, which was subjected to progressive structural damages while monitored for almost a year. The results show good performance of the proposed algorithm and highly reducing the computational cost.

This chapter presents principles and justification of diagnostic load tests of bridges as normally performed. Normally, diagnostic tests serve to verify and adjust the predictions of an analytical model. However, as presented in the chapter, the results of a diagnostic load test in a bridge can also serve other objectives. Several examples of application are presented with the main objective not only to show how the tests are carried out, but chiefly to introduce which are the main issues to take into account to obtain accurate and reliable results that can be used in the assessment of the actual capacity of the bridge. In the case of static tests, conclusions regarding the measurement stabilization time are presented. For dynamic tests in railway bridges, the extrapolation to lower and higher speeds is also discussed.

Across Europe, multiple management systems were developed with the aim of managing roadway bridges in an efficient manner. Although being generically similar, the condition assessment process, based in the as-sessment of performance indicators which are compared with performance goals in order to evaluate the ac-complishment of established quality control plans, can be identified as one difference among them. This leads to the existence of multiple different methodologies for assessing the bridge condition, and consequently to a considerable variation in roadway bridges quality. COST Action TU1406 aims to achieve the European eco-nomic and societal needs by standardizing the condition assessment and maintenance level of roadway bridg-es. For such purpose it would be required to establish the specific recommendations for the quantification of performance indicators, the definition of standardized performance goals and, finally, a guideline for quality control plans.

Life-cycle analyses are used in condition assessment of new and existing bridges, as well as for evaluation of maintenance strategies. Management systems, capturing different degradation processes, are very often used in relation to such life-cycle analyses methods in order to describe the actual and future condi-tion. During the implementation of asset management strategies, maintenance actions are required to keep as-sets at desired performance levels. In case of roadway bridges, performance indicators are established for components, which alongside with the definition of standardized performance goals, allow to assess the ac-complishment of quality control plans. In Europe there is a large disparity regarding the way performance in-dicators are quantified and goals specified. Therefore, a discussion at a European networking level, seeking to achieve a standardized approach in this subject, will bring significant benefits. COST Action TU1406 aims to achieve such goal by bringing together both research and practicing communities in order to establish a Euro-pean guideline in this matter.

Many traditional methods of damage identification in bridge structures implement numerical models and/or modal parameters as a means of condition assessment. While such techniques can often be effective, they may also succumb to their own intrinsic constraints, such as shortcoming in numerical model calibration to dynamic behaviour and environmental sensitivity of modal parameters. Furthermore, the degree of vibration signal non-stationarity that may be induced due to vehicle excitation can limit the applicability of some common signal processing techniques, such as Fourier transforms. The current study investigates vibration-based approaches to damage identification that circumvent some of these issues. Vibration data obtained from a real bridge structure subjected to a progressive damage test under vehicle induced excitation is used as a test subject. Novel vibration parameters obtained from the raw signals are assessed for their damage detection, localisation and quantification capabilities. Additionally, advanced Empirical Mode Decomposition (EMD) and the Hilbert-Huang Transformation (HHT) is applied to the non-stationary signals for the purpose of damage identification. The investigation shows that damage detection, localisation and quantification is achievable from the vehicle induced vibration signals using the proposed empirical techniques.

Tools, guidelines and standards for assessment of Life Cycle Cost (LCC) of built environment e.g. buildings, infrastructure assets etc. have gained impact over the past years. Owner and operator application of tools, guidelines and standards enhances optimization of operation and maintenance with due respect to their budgets. In order to aid owners, operators and their designers, a task group under fib has been established to prepare a state-of-the-art report regarding LCC analyses of concrete assets. The state-of-the-art report contains a description of existing LCC standards and guidelines, their applicability, the definition of different cost elements, and the treatment of uncertain information in a reliability or risk based framework, etc. providing the reader with background information and methodology for preparation of such analysis. Moreover, the report contains case studies, presenting the applicability of the LCC analysis methodology.

In Europe, there is a large disparity from country to country regarding the way performance indicators are quantified and goals and quality controls specified. The main objective of COST Action TU-1406 is to establish quality specifications for roadway bridges that could be accepted on a European basis. The application of these common specifications will be highly dependent on the changes in philosophy and operational methods (inspection, testing,…) that the new specifications will require in the future as a result of their implementation. Therefore, to reduce to a minimum the possible reluctance of operators to change the actual performance indicators and the methods to obtain them and also to take advantage of the existing background and knowledge and the data-bases available after a lot of years of use, it is mandatory that the new homogenized quality specifications proposed as result of the Action are based on the actual practice.

Many methods of damage identification in bridge structures have focused on the use of either numerical models, modal parameters or non-destructive damage tests as a means of condition assessment. These techniques can often be very effective but can also suffer from specific pitfalls such as, numerical mod-el calibration issues for nonlinear and inelastic behaviour, modal parameter sensitivity to environmental and operational conditions and bridge usage restrictions for non-destructive testing. The present paper covers al-ternative approaches to damage identification of bridge structures using empirical parameters applied to measured vibration response data obtained from two field experiments of progressively damaged bridges sub-jected to ambient and vehicle induced excitation, respectively. Numerous non-modal vibration-based parame-ters are detailed and selected for the assessment of either the ambient or vehicle induced excitation data based on their inherent properties.

The use of fiber optic sensors on civil engineering structural health monitoring (SHM) applications have become quite popular for the past two decades. Within this type of sensors however, the study and use of Optical Backscatter Reflectometry (OBR) based Distributed Optical Fiber Sensors (DOFS) is relatively new. In this way, there is still some uncertainty that would allow the use of this technology in a more systematic and standardized way. Some of this uncertainty is related with the long-term reliability behavior of these sensors when applied on the monitoring of a structure under a large number of load cycles. In this way, the authors conducted a laboratory experiment where a reinforced concrete beam was instrumented with a DOFS that was adhered in a way to allow the measuring of strain on four different longitudinal segments on its bottom surface. A fatigue test was then conducted on this element where the inputted load range was the one expected on a standard highway bridge between its self-weight and the additional traffic load. Furthermore, each longitudinal segment of the DOFS was adhered to the concrete using a different adhesive in order to assess the optimal one in these conditions. The obtained data is then compared with strain gauges that are also instrumented on the concrete beam.

The performance of four methods in establishing whether a bridge has experienced damage or not from the response to the crossing of a vehicle, is assessed within the Marie Sklodowska-Curie Innovative Training Network titled TRUSS (Training in Reducing Uncertainty of Structural Safety, http://trussitn.eu, 2015-2019). The first and second methods extract vibration based damage sensitive features and apply a Bayesian Belief network respectively from/to bridge accelerations to determine the occurrence of damage. A third method based on bridge rotations applies bridge weigh-in-motion concepts to detect damage from esti-mated vehicle’s weights. Finally, a fourth method derives bridge curvature and damage from the vehicle re-sponse. A blind test based on the responses of a complex vehicle-bridge interaction theoretical model is car-ried out to assess performance. The estimations of damage by each method are collected independently and compared to the exact solution.

The majority of bridge condition assessment methods from acceleration data incorporate the use of the Fourier Transform (FT) to obtain or assess damage sensitive features, however the accuracy of the FT’s output for non-linear and non-stationary signals can causes a problem for real-world structural applica-tions. The Hilbert–Huang Transform (HHT) has long been cited as a potential alternative to the FT for non-linear, non-stationary signals and has gathered popularity in the condition assessment of rotating machinery due to its time-frequency-energy representation. On the other hand, instances of the HHT being applied to bridge structures has been less common, predominantly due to the inconsistency of the required Empirical Mode Decomposition (EMD) phase of the methodology. The present paper utilises recent advancements in EMD methodology through the application of Improved Complete Ensemble Empirical Mode Decomposition with Adaptive Noise (ICEEMDAN), which considerably reduces the undesirable decomposition effects of signal noise contamination. A novel damage parameter is proposed that utilizes the HHT’s instantaneous out-puts to successfully achieve damage identification in a real bridge structure subjected to a progress damage test under single vehicle excitation.

This issue is a snapshot of the newest research in SHM for civil structures, and it includes a range of topics such as data processing algorithms to detect damage, modeling, and simulation [1–15]; sensor development and experiments [16–26]; materials studies [27,28]; state-of-the-art reviews [29,30]; and case studies [31]. SHM is highly multi-disciplinary, and advances in other areas of study can likely be recruited for the progress of SHM. The future of this field is very bright, and will be a driver for the coming futuristic, intelligent infrastructure.

The process of damage identification in bridge structures traditionally involves the extraction of one or more of the numerous modal-based Damage Sensitive Features (DSFs) from vibration data obtained by direct sensor measurement. However the performance of these modal-based DSFs can suffer under chang-ing environmental and operational conditions and are generally limited by their methodology, which assumes linear structural behaviour and signal stationarity. The present paper presents a detailed overview of the de-velopment of alternative DSFs derived from vibration characteristics, focusing on their conception, damage sensitivity evaluation and performance robustness assessment. Initially, selected vibration parameters are out-lined before their damage sensitivity is determined on progressive damage test data obtained from a post-tensioned three-span bridge under ambient conditions using supervised machine learning techniques in con-junction with the Minimum Covariance Determinate (MCD) estimator to mitigate uncertainty surrounding sources of excitation. Secondly, the performance robustness of the vibration-based DSFs is assessed on highly non-stationary data obtained from a progressively damaged steel truss bridge subjected to vehicle induced ex-citation. Finally, a comparative evaluation of the vibration-based DSFs is made against modal-based DSFs performance from the literature.

The authors conducted a laboratory experiment where two reinforced concrete beams were instrumented with a Distributed Optical Fiber Sensors that were adhered to allow the measuring of strain on four different longitudinal segments on their bottom surface. A fatigue test was then conducted on these elements where the load range was the one expected on a standard highway bridge between its permanent and the additional traffic load. Furthermore, each longitudinal segment of the DOFS was adhered to the concrete using a different adhesive in order to assess the optimal one in these fatigue conditions. The obtained data is then compared with strain gauges that were also instrumented on the concrete beams.

The research we introduce in the paper is intended to model and to infer on the durability of architectural fronts, composed of the facades of buildings, by designing a predictive system. The estimation is based on survival analysis techniques, from a non-parametric approach. The ultimate aim is to develop a robust and flexible platform for the data collection and analysis able to be implemented in any city in the world. In this sense, the Building Research Analysis and Information Network (BRAIN hereinafter) will be introduced in detail. BRAIN, as a powerful tool, will allow making strategic decisions for the maintenance and the sustainability of the building stock.

This paper reports on recent contributions by the Marie Sklodowska-Curie Innovative Training Network titled TRUSS (Training in Reducing Uncertainty of Structural Safety) to the field of structural safety in rail and road bridges (http://trussitn.eu). In TRUSS, uncertainty in bridge safety is addressed via cost efficient structural performance monitoring and fault diagnostics methods including: (1) the use of the rotation response due to the traffic traversing a bridge and weigh-in-motion concepts as damage indicator, (2) the combination of design parameters in probabilistic context for geometrical and material properties, traffic data and assumption on level of deterioration to evaluate bridge safety (via Bayesian updating and a damage indicator based on real time measurement), (3) the application of a fuzzy classification technique via feature selection extracted using empirical mode decomposition to detect failure, and (4) the testing of alternative vibration based damage sensitive features other than modal parameters. Progress is also made in improving modern technologies based on optical fiber distributed sensing, and sensors mounted on instrumented terrestrial and on aerial vehicles, in order to gather more accurate and efficient info about the structure. More specifically, the following aspects are covered: (a) the spatial resolution and strain accuracy obtained with optical distributed fiber when applied to concrete elements as well as the ideal adhesive, and the potential for detecting crack or abnormal deflections without failure or debonding, (b) the possibility of using the high-resolution measurement capabilities of the traffic speed deflectometer for bridge monitoring purposes and, (c) the acquisition of bridge details and defects via unmanned aerial vehicles.

Road asset management is a task of great responsibility, since it involves vital assets to the community. An efficient transportation network is essential for the modern society from the economic, societal and environmental point of view. Today, it is a challenge for operators to manage road infrastructures under their responsibility in an efficient way, meeting the present and future needs of the community they serve. For this purpose, authorities need to produce an asset management plan which should not only define the goals to be achieved by exploiting the roadway bridge network, but that should also identify the investment needs and priorities based on a life cycle cost criteria. In addition, a proper condition assessment of these assets must be conducted to support the decision-making process regarding their preservation.

This is the peer reviewed version of the following article: [Cavaco ES, Neves LAC and Casas JR. Reliability-based approach to the robustness of corroded reinforced concrete structures. Structural Concrete. 2017;18:316–325. https://doi.org/10.1002/suco.201600084], which has been published in final form at http://onlinelibrary.wiley.com/doi/10.1002/suco.201600084/abstract. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving. Currently, decisions on the maintenance and repair of infrastructural assets, structures in particular, are mostly based on the results of inspections and the resulting condition index, neglecting system robustness and therefore not making optimal use of the limited funds available. This paper presents a definition and a measure of structural robustness in the context of deteriorating structures which are compatible with asset management systems for optimal maintenance and repair planning. The proposed index is used to define the robustness of existing reinforced concrete (RC) structures to rebar corrosion. Structural performance and the corresponding reliability index are assessed using combined advanced reliability and structural analysis techniques. Structural analysis explicitly includes deterioration mechanisms resulting from corrosion, such as reinforcement area reduction, concrete cracking, and bond deterioration. The first-order reliability method, combined with a response surface algorithm, is used to compute the reliability index for a wide range of different corrosion levels, resulting in a fragility curve. Finally, structural robustness is computed and discussed based on the results obtained. A robustness comparison of different structures can then be used to determine structural types more tolerant to corrosion and these results used for planning maintenance and repairs.

During implementation of asset management strategies, maintenance actions are required in order to keep assets at desired performance levels. In case of roadway bridges, specific performance indicators are established for their components and compared with performance goals in order to evaluate if quality control plans are accomplished. In Europe there is a large disparity regarding the way these indicators are quantified and how such goals are specified. Therefore, due to the considerable number of methodologies, arises COST Action “TU1406: Quality specifications for roadway bridges, standardization at a European level (BridgeSpec)” which aims to bring together, for the first time, both research and practicing community in order to accelerate the establishment of a European guideline in this subject. It is therefore intended to proceed with the identification and description of these indicators, addressing the way they are assessed (e.g. visual inspection, non-destructive tests and monitoring systems), with what frequency, what values are generally obtained and, finally, some general recommendations with the aim of establishing a new European standard in bridge condition assessment.

Roadway bridges, being one of the most critical road infrastructures components, require regular maintenance actions. Therefore, it becomes important to define strategies to maximize societal benefits, derived from the investment made in these assets. Consequently, this investment should be planned, effectively managed and technically supported by appropriate management systems. For this purpose, authorities need to produce an asset management plan which should, not only define the goals to be achieved by ex-ploiting the roadway bridge network, but also identify the investment needs and priorities based on a life cycle cost criteria. Additionally, a proper condition assessment of these assets must be conducted to support the decision-making process regarding their preservation.

Overtime, the structural condition of bridges tends to decline due to a number of degradation processes, such as; creep, corrosion and cyclic loading, among others. Considerable research has been conducted over the years to assess and monitor the rate of such degradation with the aim of reducing structural uncertainty. Traditionally, vibration-based damage detection techniques in bridges have focused on monitoring changes to modal parameters and subsequently comparing them to numerical models. These traditional techniques are generally time consuming and can often mistake changing environmental and operational conditions as structural damage. Recent research has seen the emergence of more advanced computational techniques that not only allow the assessment of noisier and more complex data, but also allow research to veer away from monitoring changes in modal parameters alone. This paper presents a review of the current state-of-the-art developments in vibration based damage detection in small to medium span bridges with particular focus on the utilisation of advanced computational methods, such as machine learning, pattern recognition and advanced data normalisation algorithms.

In Europe, there is a large disparity from country to country regarding the way performance indicators are quantified and goals specified. The main objective of COST Action TU-1406 is to establish quality specifications for roadway bridges based on reliable and widely accepted performance indicators that could be accepted on a European basis. The application of these common specifications will be highly dependent on the changes in philosophy and operational methods (inspection, testing,…) that the new specifications will require in the future as a result of their implementation. Therefore, to reduce to a minimum the possible reluctance of highway managing Agencies to change the actual performance indicators and the methods to obtain them and also to take advantage of the existing background and knowledge in the data-bases available after a lot of years of use, it is mandatory that the new homogenized quality specifications proposed as result of the Action, are more or less based on the actual practice. As a consequence, before any proposal is made, it is of interest to get an overview of the existing performance indicators and performance goals used in different countries and by different highway agencies, owners and operators all over Europe as well as the quality specifications for roadway bridges. To this end, a survey was developed within the COST action TU-1406 to gather the existing state-of-the art in Europe. This paper shows the methods used to gather the information, some preliminary results and the main conclusions for the next steps to take on.

In Europe, there is a large disparity from country to country regarding the way performance indicators are quantified and goals specified. The main objective of COST Action TU-1406 is to establish quality specifications for roadway bridges that could be accepted on a European basis. The application of these common specifications will be highly dependent on the changes in philosophy and operational methods (inspection, testing,…) that the new specifications will require in the future as a result of their implementation. Therefore, to reduce to a minimum the possible reluctance of highway managing Agencies to change the actual performance indicators and the methods to obtain them and also to take advantage of the existing background and knowledge and the data-bases available after a lot of years of use, it is mandatory that the new homogenized quality specifications proposed as result of the Action, are more or less based on the actual practice. As a consequence, before any proposal is made, it is of interest to get an overview of the existing performance indicators and performance goals used in different countries and by different highway agencies, owners and operators all over Europe as well as the quality specifications for roadway bridges. To this end, a survey was developed within the COST action to gather the existing state-of-the art in Europe. This paper shows the methods used to gather the information, the expected input and the main conclusions.

Along the years, there were efforts by researchers in quantifying structural performance and damage in function of vibration measurements. Curves proposed by several authors try to relate acceleration spectrum to damage level, which was determined based on experimental survey accomplished on buildings. The present work investigates a vibration based criteria for bridge structures as a basis to evaluate damage and performance in existing bridges and also to be used for long-term performance at the time of bridge design. With this purpose, it was analyzed a data base of Brazilian bridges which were structurally identified and had their dynamic effects measured during traffic flow. For the damage evaluation, a damage index based on the change of the dynamic properties and the general condition of these structures observed during a detailed inspection were taken into account. After that, damage indexes were related to measured vibration too. The results show a clear correlation between the damage index and the fatigue reliability index with the intensity of bridge vibration. As a final result, from the observed correlations, limits of acceleration are proposed to be considered in existing and newly designed bridges to certify a correct long-term condition and safety to fatigue effects. A critical approach of current Brazilian Standard (NBR-15307 2005) which suggests damage estimation in function of bridge vibration index is also carried out.

Corrosion in reinforced concrete and steel structures is among the most damaging phenomena to structural safety and therefore one of the most demanding when facing the life-cycle analysis of such structures. However, the onset and progression of corrosion is highly uncertain. Because damage due to corrosion appears due to environmental aggressive agents which progress on time, it is of interest to develop suitable life-cycle measures of structural robustness with respect to a progressive deterioration of the structural system performance. In this paper, a robustness-based approach as presented in Cavaco et al. (2013) is used to quantify the effect of corrosion on safety and life-cycle maintenance. The level of corrosion is considered as an uncertain parameter. In this way, a probabilistic measure of the robustness, seen as the tolerance to damage, can provide a comprehensive description of the life-cycle system performance. Therefore, a robustness definition and the calculation of the corresponding robustness index are proposed in the paper and further applied to one reinforced concrete and one steel existing bridge to show the practical application and results when applied to real bridges. It is shown how the obtained robustness index for the bridges can be directly co-related to their life-cycle performance and also used to define the optimum intervention strategies.

The paper shows how the robustness concept, mainly developed and thought for the design of new structures, and the monitoring by suitable sensors based on fiber optics can also play a relevant role in the safety and management of existing bridges. A new approach of robustness more related to the long-term and service life of bridges is presented and its advantages in the decision-making process during the management of existing bridges are highlighted and afterwards applied on a real bridge. The continuous-in-space monitoring by the use of distributed optical fiber systems is also presented and the promising results and advantages regarding the flexural cracking assessment in concrete elements are shown.

The use of Optical Backscatter Reflectometer (OBR) as a distributed fiber optic system to measure strain and detect cracking in concrete structures is investigated. A laboratory experience in a concrete slab is first presented and after this pilot test, a full-scale bridge load test was used to investigate the effectiveness of the OBR technology monitoring system when applied to real structures. The bridge monitoring consisted of the installation of 100m of optic fiber in the soffit of the prefabricated bridge beams. Strain readings obtained from the optic fibers were compared to results from previous identical load tests applied to the bridge, confirming the high accuracy inherent in the optic fiber technology. Subsequently, the cooling tower of a power plant was monitored using the OBR sensor system. A total of 300 meters of cooling tower are monitored and 30,000 points on the concrete surface (inner and outer of shell) are interrogated. The obtained results show the feasibility of this technique despite the roughness of the concrete surface and the heterogeneity due to the presence of aggregates of different sizes. All applications verify that the OBR sensor is not only able to detect appearing cracks that are hardly visible, but it is also able to perform robustly and with high accuracy up to a load level producing a crack width in the range of 1 mm. Moreover, the OBR frequency signal is acquired properly and provides correct strain values without breaks, even at a high load level. Regarding economic impact, deployment of the OBR monitoring system presents a financial advantage over equivalent monitoring techniques (number of points interrogated).

The interest of this research is motivated by the huge constructive development in the building sector, which has led to an enormous volume of buildings worldwide over the last decades. This fact, as well as poor management in conservation of buildings, mainly in urban cities, has led to total degradation situations on the facades of building stocks. To infer on the evolutional process of degradation that occurs in the facade, during its service life and based on the information obtained from inspections, the method for the data analysis (e.g. survival analysis techniques) is as important as the truthfulness and usefulness of the data collected on the subjects (facades) under study. In this paper we propose a method based on the design of indicators for prospecting and global data collection on the injury state of the inspected facades. The method analyzes how to perform the identification, classification, methodology, resources and quality of the data in order to be reliable, testable and measurable. The proposed model enables the macro inspection and monitoring of large-scale urban zones and the data obtained allow the researcher to understand and manage the predictive degradation phenomenon and, in turn, eliminate potential risks in the urban front.

In this paper a framework for assessing the robustness of existing reinforced concrete structures under corrosion is presented. Robustness is defined as a structural property related to the tolerance to damage and is measured by ithe mean performance considering all possible damage scenarios. The proposed methodology is driven to meet the requirements of the structural maintenance interventions in the real lite, as it can be used to define the structural types with longer lifecycles (including both deterioration and loading) or, alternatively, those which may present longer time interval between maintenance/strengthening operations. This is an important issue when dealing with the life-cycle management of existing deteriorated structures. In fact, when facing limited funding for the management of a large stock of bridges, the crucial question is whether postponing a specific repair/strengthening work increases the repair cost disproportionately. Firstly, a robustness index based on the deterioration process is proposed and explained. Secondly, the application to two real bridges shows how this index may help to solve the question and to see which bridges are more sensitive to a postponing of the maintenance works, based on a life-cycle approach.

The present paper presents a theoretical study of the advanced assessment implementation methodology through the application of a Structural Health Monitoring system (SHM) to update the level of seismic risk of existing bridges. Since seismic risk is defined as the economic impact of an earthquake’s damage, both mitigation and constructive measures should be implemented in order to reduce the damage when such extreme event occurs. To this end, in existing bridges placed in areas with a high seismic activity, an advanced assessment should be carried out. The evaluation must be done not only in those which are considered of major importance in an emergency case but also all those that may be susceptible to be indispensable when the main ones might suffer severe damages that may render them unserviceable. Therefore, it is about to assess the importance and feasibility of implementing a SHM system such that the status and real behavior of the bridge in front of extreme events (earthquakes) can be known. With the results obtained through the SHM system, different parameters that can define the level of seismic risk of the structure can be updated. This evaluation would allow to compare and propose different options of repair and / or maintenance in order to increase the capacity of the bridge and thus to reduce the seismic risk of the structure. Then, an optimization of the resulting costs would be possible.

This study focuses on a new strengthening method of continuous bridges with several spans that present extensive damage in their foundation/piers due to scour and erosion. The method consists on the construction of a new upper steel arch with a network hanger's arrangement over the original deck with the aim to hang the existing deck to the new arch. The deck is acting as a tie in the new structural configuration. This allows to remove the damaged foundations/piers, deriving on an arch bridges with an span-length similar to the total length of the strengthened bridge and avoiding future problems related to scouring. The paper discusses about the resisting mechanisms that control the structural optimization process and therefore defines the design criteria. The main target of this process is different for each case, namely: the optimization of the arch in traditional network bridges; the limitation of maximum and minimum stresses in the deck in the case of strengthened bridges. Finally, it allows the comparison of each case, setting the differences between them and providing a new line of research on the topic of the tied arch method.

In the last few years, research on techniques that permit the reduction or even the complete elimination of structural bar reinforcements has been intensified. The addition of steel fibres to the concrete matrix is proven to be an effective way of covering the deficiencies in this material when subjected to tensile stress. However, there still exists uncertainty surrounding some of the basis of design of structural members in ultimate condition. A clear example is the partial safety factor applied to the tensile strength. In this paper, a reliability-based analysis is carried out through the study of a particular application, such as the tunnel lining concrete segments built in an experimental section of the L9 Metro tunnel in Barcelona, solely reinforced with steel fibres. Specimens were extracted from three different segments and tested in tension by using the Barcelona test. Such a representative sample of tensile strength results made possible an assessment of the degree of the existing safety in this particular case by applying the reliability method FORM. The reliability analysis suggested a partial factor equal to 1.77. This would represent a first step to obtain the general material safety factor, which may involve a calibration in a wide range of tunnel segments and afterwards, other structural members and applications of SFRC.

Structural Health Monitoring is becoming more and more used in civil engineering infrastructure. The technology for implementing SHM applications is presented in this Chapter. Details on instrumented civil constructions are then discussed, together with most innovative future trends.

Along the years, researchers have made efforts in the sense of quantifying structural performance and damage in function of vibration measurements, [1] and [2]. Similarly the present work investigates a vibration based criteria for bridge structures as a basis to evaluate damage in existing bridges. With this purpose, a bridge data base collected during field tests accomplished in Brazilian bridges was used. The results show a clear correlation between the damage index and the intensity of bridge vibration. As a final result, from the observed correlations, limits of acceleration are proposed to be considered in existing bridges to certify a correct long-term condition. A critical approach of current Brazilian Standard (NBR-15307 2005) which suggests damage estimation in function of bridge vibration is also carried out.

This paper presents a detailed study of the construction and cable-stressing process for the strengthening of bridges by the conversion of the structural typology from continuous beams to tied-arch bridges. The basic stages of the construction method and the basic assumptions of the study and applications of stress method, based on automated optimization using genetic algorithms, are described. Additionally, a criterion of design variables, constraints and objective functions are defined. Finally, an example of application to the San Luis Bridge in Chile is presented and illustrates the use of the algorithm.

Corrosion of reinforcement bars in concrete structures is the most significant deterioration mechanism in these structures. Corrosion is extremely difficult to predict and, consequently, can be regarded as an unpredictable event. Following this, robustness assessment methods can be employed to define the susceptibility of a structure to corrosion. In this paper a strategy to evaluate the impact of corrosion on the robustness of reinforced concrete structures is presented. To assess robustness the index proposed by Cavaco et al. [1] is adopted. This index, Rd , is defined based on an average of the structure reliability variation with corrosion. To calculate the reliability index of the corroded structure, a nonlinear analysis of the cross section, coupled with a First Order Reliability Method (FORM) analysis, is performed. To predict bond strength deterioration the M-Pull model proposed by [2] is considered. Results show that structure reliability is significantly affected by reinforcement corrosion. The most important factor causing load capacity decreasing is bond strength deterioration. Independently of the reinforcement ratio the residual reliability tends to a lower bound, corresponding to the resistance of the unreinforced concrete section. At this stage no adhesion exists between steel and concrete. The susceptibility of different design solutions is compared in terms of the robustness indicator, Rd, showing that, although less reinforced structure reveals a lower safety level, they are more robust since that safety level is less affected by corrosion.

The increasing volume of European transport urgently requires an effective road and rail system in Central European and Eastern countries (CEEC) with a major investment in building new and assessing and rehabilitating old structures. To decrease the number of bridges in CEEE to be strengthened or replaced due to lack of maintenance or increase of the trucks weight, it is essential to assess accurately their remaining capacity. It becomes important to develop more appropriate tools and procedures to avoid unnecessary interventions in bridges. Load testing carried out on bridges through years indicates that often bridges resist load in ways not always considered in the design or in the present bridge rating procedures. Therefore, substantial benefits can be realized if the bridges can be evaluated and rated based on non-destructive load tests and if the actual traffic loads can be well monitored as well, including their dynamic effect or dynamic allowance.

During the last decade, extensive research efforts were expended in Europe to develop new techniques for the assessment, rehabilitation and management of existing bridges. Several European-wide research projects that addressed these topics have been recently completed including: BRIME, COST345, SAMARIS, Sustainable Bridges and ARCHES. These projects led to the development of several guidelines providing state-ofthe-art methods for the safety assessment of existing bridges. However, the implementation of these proposed guidelines might be difficult in many European countries due to the lack of national documents that will legally approve their practical application. Furthermore, the guidelines are presented as state-of-the-art solutions rather than as codes or specifications and thus may be difficult to follow by less experienced engineers. To help in expediting the implementation of the proposed guidelines, this paper proposes the development of a new Eurocode for Bridge Safety Assessment. The key elements of such a code are presented including: 1) the use of probability based assessment, 2) the use of redundancy and robustness criteria, 3) the use of site-specific loads, 4) methods for incorporating diagnostic test data, and 5) methods for incorporating proof load test data.

The paper describes two possible alternatives of Structural Health Monitoring (SHM) as a solution for the inspection and maintenance of cable-stayed bridges. Especially, it covers the problem of the quantitative deployment of the stay- force measuring devices and foreseen benefits from their application. Deliberations are conducted on the basis of a newly designed cable-stayed bridge in Poland, fully equipped with a long term, remote SHM. Under consideration are two possible monitoring solutions, according to the state of the art in the field of the force measurements: Measurement of the forces by means of accelerometers or by elasto-magnetic sensors. It is presented the selection of the monitoring devices and the optimal number to be used based on the minimization of the total expected cost of the bridge, including the cost of monitoring. The main objective of the example is to mature these methods and highlight their influence on the total cost of the bridge, considering a life-cycle cost analysis.

This main objective of this research is to evaluate the variability of the mechanical properties (compressive strength, modulus of elasticity and tensile strength) and bond strength of the self-compacting concrete (SCC), with 50 MPa compressive strength at 28 days, varying the maximum aggregate size and the SCC fluidity. The tests were made in 15 x 30 cm concrete cylinders and in beams standardized by Rilem-Ceb-Fib (1973). In agreement with the obtained results, can be concluded that the variability of the self-compacting concrete is small for the modulus of elasticity and for the compressive strength, but the tensile strength presented a significant variability due to the failure mode. About the bond strength, the variability was small showing that the self-compacting concrete is reliable and possesses great potential for use in the civil construction.