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In the H2020 European project ASHVIN "Assistants for Healthy, Safe, and Productive Virtual Construction Design, Operation & Maintenance using a Digital Twin", a set of Key Performance Indicators (KPIs) and Performance Indicators (PIs) to plan and control productive, resource efficient, and safe maintenance are being developed for transport infrastructure. This paper is presenting PIs and KPIs for the assessment and monitoring of the following aspects: Productivity, Resource Efficiency, Cost, Health & Safety during the operational life cycle stage, which is mainly focusing on the inspection and maintenance planning. Quantifiable and measurable PIs and KPIs are proposed and applied on two demonstration projects, highway bridge in Spain and airport runway in Croatia, as part of transportation infrastructure. Proposed PIs and KPIs are integrated into digital twins of the analyzed assets and into decision making tools for risk based maintenance planning. This paper presents the overview of the proposed digital PIs and KPIs applied on two demonstration projects and the integration into decision support tools for efficient and sustainable maintenance planning. [ABSTRACT FROM AUTHOR]

We live in an environment of ever-growing demand for transport networks, which also have ageing infrastructure. However, it is not feasible to replace all the infrastructural assets that have surpassed their service lives. The commonly established alternative is increasing their durability by means of Structural Health Monitoring (SHM)-based maintenance and serviceability. Amongst the multitude of approaches to SHM, the Digital Twin model is gaining increasing attention. This model is a digital reconstruction (the Digital Twin) of a real-life asset (the Physical Twin) that, in contrast to other digital models, is frequently and automatically updated using data sampled by a sensor network deployed on the latter. This tool can provide infrastructure managers with functionalities to monitor and optimize their asset stock and to make informed and data-based decisions, in the context of day-to-day operative conditions and after extreme events. These data not only include sensor data, but also include regularly revalidated structural reliability indices formulated on the grounds of the frequently updated Digital Twin model. The technology can be even pushed as far as performing structural behavioral predictions and automatically compensating for them. The present exploratory review covers the key Digital Twin aspects—its usefulness, modus operandi, application, etc.—and proves the suitability of Distributed Sensing as its network sensor component. [ABSTRACT FROM AUTHOR]

Distributed optical fiber sensors are measuring tools whose potential related to the civil engineering field has been discovered in the latest years only (reduced dimensions, easy installation process, lower installation costs, elevated reading accuracy, and distributed monitoring). Yet, what appears clear from numerous in situ distributed optical fiber sensors monitoring campaigns (bridges and historical structures among others) and laboratory confined experiments is that optical fiber sensors monitorings have a tendency of including in their outputs a certain amount of anomalistic readings (out of scale and unreliable measurements). These can be both punctual in nature and spread over all the monitoring duration. Their presence strongly affects the results both altering the data in its affected sections and distorting the overall trend of the strain evolution profiles, thus the importance of detecting, eliminating, and substituting them with correct values. Being this issue intrinsic in the raw output data of the monitoring tool itself, its only solution is computer-aided post-processing of the strain data. This article discusses different simple algorithms for getting rid of such disruptive anomalies using two methods previously used in the literature and a novel polynomial-based one with different levels of sophistication and accuracy. The viability and performance of each are tested on two study case scenarios: an experimental laboratory test on two reinforced concrete tensile elements and an in situ tunnel monitoring campaign. The outcome of such analysis will provide the reader with both clear indications on how to purge a distributed optical fiber sensors-extracted data set of all anomalies and on which is the best-suited method according to their needs. This marriage of computer technology and cutting edge structural health monitoring tool not only elevates the distributed optical fiber sensors viability but also provides civil and infrastructures engineers a reliable tool to perform previously unreachable levels of accuracy and extension monitoring coverage. [ABSTRACT FROM AUTHOR]

Distributed Optical Fiber Sensors (DOFSs), thanks to their multiple sensing points, are ideal tools for the detection of deformations and cracking in reinforced concrete (RC) structures, crucial as a means to ensure the safety of infrastructures. Yet, beyond a certain point of most DOFS-monitored experimental tests, researchers have come across unrealistic readings of strain which prevent the extraction of further reliable data. The present paper outlines the results obtained through an experimental test aimed at inducing such anomalies to isolate and identify the physical cause of their origin. The understanding of such a phenomenon would enable DOFS to become a truly performant strain sensing technique. The test consists of gradually bending seven steel reinforcement bars with a bonded DOFS under different conditions such as different load types, bonding adhesives, bar sections and more. The results show the bonding adhesives having an influence on the DOFS performance but not on the rise of anomalies while the reasons triggering the latter are narrowed down from six to two, reaching a strain threshold and a change in structure’s deformative behavior. Further planned research will allow identification of the cause behind the rise of strain-reading anomalies. [ABSTRACT FROM AUTHOR]

In engineering, quality control in systems development ensures that products and services meet expectations. There is an increasing need to develop strategies to ensure asset quality and reduce the risk of unexpected costs. Ensuring the desired service quality with minimum interruptions requires maintenance actions when the risk of service impairment, interruption or losses in life-cycle costs reach predefined levels, which are based on performance indicators. This paper analyses a digital image correlation (DIC) system and its ability to assess performance indicators such as crack patterns, crack openings and vertical and horizontal deformation. The obtained values are then compared to goals so that structural performance assessment strategies can be implemented in an efficient and sustainable way. In particular, the system is used to obtain valuable information about the shear transfer mechanisms of reinforced concrete beams. This contribution focuses on prestressed precast beams loaded in shear following a sequence of loading and unloading cycles before the load is ultimately increased until failure. The obtained results include a load-dependent photogrammetric documentation of crack patterns, a continuous quantification of crack openings and an accurate measurement of vertical and horizontal deformation. These findings are basic elements for the enhancement and assessment of existing analytical formulations. [ABSTRACT FROM AUTHOR]

Over the years, there have been numerous efforts by researchers in quantifying structural degradation and damage from vibration measurements. Traditionally, damage detection techniques in bridges have focused on the use of modal-based damage indicators, such as frequencies, mode shapes and mode shape derivatives. However, these parameters have been shown to be sensitive to environmental and operational variations and can be difficult to accurately extract under low-level ambient excitation. Recent research has found a correlation between certain vibration parameters, such as vibration intensity, and a group of damage bridges, suggesting that vibration parameters may detect damage if extracted correctly. The present study furthers these findings by examining a number of vibration parameters as damage indicators to discern their sensitivity to various condition states of a progressively damaged bridge under ambient excitation. [ABSTRACT FROM AUTHOR]

Load testing method is a significant tool in the assessment of bridge safety. One type of load tests is diagnostic load testing, the aim of which is to establish a comparison between real bridge behaviour and analytical calculation. It can be used either as acceptance test of the structures or as an estimation tool for the load carrying capacity of the already existing structures that have been in service for some time. This article presents diagnostic load tests and three examples of their application to various bridge structures and emphasises their diagnostic potential for assessment. In the majority of cases of diagnostic load tests presented in the literature, the experimental results (deflections, strains, etc) are very close or lower than the predicted ones and for this reason, such tests are expected to validate the existing structure. However, in the cases presented here, it is shown how the experimental results differ considerably from the expected ones. Since the theoretical and the experimental results of all three examples did not match, it was highly recommended to keep the matter under close investigation. A deep insight into the bridges showed serviceability and safety concerns and in some cases a repair/strengthening was necessary. [ABSTRACT FROM PUBLISHER]

In this paper, current and proposed methodologies for assessing the robustness and redundancy of bridge structures are discussed and an overview of the latest advances in research is presented along with proposals for implementation in bridge design and evaluation codes. In particular, European and North American standard codes and guidelines, including the Eurocode, AASHTO, and the Canadian Standards Association (CSA), as well as some national European codes and related guidelines, are compared. Research projects, including those of the European Cooperation of Science and Technology (COST) and the U.S. National Cooperative Highway Research Program (NCHRP), represent key links between research activities and the need for implementing concepts of structural redundancy and robustness into the codes. The activities undertaken by COST and NCHRP constitute attempts to synthetize, simplify, and implement theoretical concepts that have been discussed over many years. This review shows that the U.S. approach concentrates on developing tools and criteria for the numerical evaluation of the capability of a bridge structure to continue to carry load after the failure of a member, whereas the European approach, still in a more theoretical phase, lacks specific guidelines for bridges and uses available building recommendations. This paper also presents a critical assessment of the state of the art and argues that criteria implementable in future generations of bridge codes should be based on quantifiable measures of risk, which is a subject still in its very early stages of development. [ABSTRACT FROM AUTHOR]

This article presents a summary description of the main safety criteria and requirements adopted in the ‘Guideline for Load and Resistance Assessment of Existing European Railway Bridges – advices on the use of advanced methods’ (SB-LRA, 2007. Prepared by Sustainable Bridges – a project within EU FP6. Available from:www.sustainablebridges.net) developed within the European project Sustainable Bridges – Assessment for Future Traffic Demands and Longer Lives. It shows selected safety formats recommended for the assessment of existing bridges, starting from the most simple, for the member level assessment, and ending with the most advanced, for the probabilistic non-linear assessment of a bridge system. The article also presents simplified methods for the probabilistic non-linear assessment of bridge systems. Furthermore, it shows probabilistic models for the resistance of selected types of bridge main carrying members that may be used in the simplified probabilistic assessment of existing railway bridges. [ABSTRACT FROM PUBLISHER]

As in any engineering application, the problem of structural assessment should face the different uncertainties present in real world. The main source of uncertainty in Health Monitoring System (HMS) applications are those related to the sensor accuracy, the theoretical models and the variability in structural parameters and applied loads. In present work, two methodologies have been developed to deal with these uncertainties in order to adopt reliable decisions related to the presence of damage. A simple example, a steel beam analysis, is considered in order to establish a liable comparison between them. Also, such methodologies are used with a developed structural assessment algorithm that consists in a direct and consistent comparison between sensor data and numerical model results, both affected by uncertainty. Such algorithm is applied to a simple concrete laboratory beam, tested till rupture, to show it feasibility and operational process. From these applications several conclusions are derived with a high value, regarding the final objective of the work, which is the implementation of this algorithm within a HMS, developed and applied into a prototype structure. [ABSTRACT FROM AUTHOR]