Structural health monitoring of bridges for improving transportation security

Structural health monitoring (SHM) is a promising technology for determining the condition of significant transportation structures objectively for efficient management and preservation of transportation assets. In addition to identifying, locating, and quantifying damage and deterioration due to effects of operation, aging, and natural hazards, the need for taking terrorism-related hazards into account has become evident after 9/11 terrorist attacks. Key transportation facilities like major bridges were identified by Department of Homeland Security (DHS) as possible terrorist targets since their loss or even temporary deficiency could lead to major impacts on economy and mobility. Several governmental, local, and private organizations have been working on identifying possible modes of threats, determining and sorting vulnerable structures, and establishing ways to prevent, detect and respond to such attacks. Authorities are also investigating ways to integrate current and future bridge management systems with security surveillance systems. Highway bridges are key links of the transportation system. This paper reviews security measures for bridges and discuss possible integration of structural health and security monitoring for improving security and safety of bridges and emergency management after a natural or man-made disaster

Structural health monitoring of in-service tunnels

This work presents an overview of some of the most promising technologies for the structural health monitoring (SHM) of in-service tunnels. The common goal of damage or unusual behaviour detection is best pursued by an integrated approach based on the concurrent deployment of multiple technologies. Typically, traditional SHM systems are installed in problematic or special areas of the tunnels, giving information on conditions and helping manage maintenance. However, these methodologies often have the drawbacks of forcing the interruption of traffic for SHM system installation and monitoring only selected portions. Alternative solutions that would make it possible to keep the tunnel in normal operation and/or to analyse the entire infrastructure development through successive and continuous scanning stages, would be beneficial. In this paper, the authors will briefly review some traditional monitoring technologies for tunnels. Furthermore, the work is aimed at identifying alternative solutions, limiting or avoiding traffic interruptions

Integration of BrIM and BMS to support bridge life-cycle management

The implementation of Bridge Management Systems (BMS) dates back to the 1970s and its adoption is nowadays generalized worldwide. Initially, they were used only as a database but, in the last decades, BMS potential is being highlighted. Tools to perform data analysis, integrating performance prediction models, have been added to the most advanced BMS. These are essential to support bridge managers in scheduling their maintenance interventions thus assuring their functionality conforms to the predefined expectations. Most of the existing BMS are currently software tools able to integrate a set of stakeholders involved during the bridge management. Hence, the adaptation of BMS to a digital environment must consider that aspect. In this regard, choosing an information exchange format that allows taking BMS into a digital context yet maintaining the interoperability between different stakeholders and their tools of preference is mandatory. In the context of construction’s digitalization, Building Information Modelling (BIM) is the main method being adopted. However, BIM was initially conceived for buildings, thus adaptation efforts are ongoing to also include other types of constructions, namely, civil infrastructures to which the bridges category belongs. This led to the appearance of the Bridge Information Modelling (BrIM) concept, which represents for bridges what BIM represents for buildings. The most widely used format in the BIM context for interoperability purposes is IFC. IFC is an open format that allows software vendor-independent data exchange. In this context, this paper presents an assessment of the existing knowledge about the applicability of the IFC for modelling bridge data. A review is made to verify the feasibility of using the current IFC version to describe the information contained in BMS. Main limitations are identified, and opportunities discussed, namely how the current IFC schema can be adapted to face the missing entities

Editorial. The crux in bridge and transport network resilience - advancements and future-proof solutions

Bridges and critical transport infrastructure (CTI) are primary infrastructure assets and systems that underpin human mobility and activities. Loss of the functionality of bridges has consequences on the entire transport network, which is also interconnected with other networks, therefore cascading events are expected in the entire system of systems, leading to significant economic losses, business, and societal disruption. Recent natural disasters revealed the vulnerabilities of bridges and CTI to diverse hazards (e.g. floods, blasts, earthquakes), some of which are exacerbated due to climate change. Therefore, the assessment of bridge and network vulnerabilities by quantifying their capacity and functionality loss and adaptation to new requirements and stressors is of paramount importance. In this paper, we try to understand what are the main compound hazards, stressors and threats that influence bridges with short- and long-term impacts on their structural capacity and functionality and the impact of bridge closures on the network operability. We also prioritise the main drivers of bridge restoration and reinstatement, e.g. its importance, structural, resources, organisational factors. The loss of performance, driven by the redundancy and robustness of the bridge, is the first step to be considered in the overall process of resilience quantification. Resourcefulness is the other main component of resilience here analysed

Opportunities and Challenges in Health Monitoring of Constructed Systems by Modal Analysis

Dynamic testing of constructed systems was initiated in the 1960’s by civil engineers interested in earthquake hazards mitigation research. During the 1970’s, mechanical engineers interested in experimental structural dynamics developed the art of modal analysis. More recently in the 1990’s, engineers from different disciplines have embarked on an exploration of health monitoring as a research area. The senior writer started research on dynamic testing of buildings and bridges during the 1970’s, and in the 1980’s collaborated with colleagues in mechanical engineering who were leading modal analysis research to transform and adapt modal analysis tools for structural identification of constructed systems. In the 1990’s the writer and his associates participated in the applications of the health monitoring concept to constructed systems. In this paper, the writers are interested in sharing their experiences in dynamic testing of large constructed systems, namely, MIMO impact testing as well as output-only modal analysis, in conjunction with associated laboratory studies. The writers will try to contribute to answering some questions that have been discussed in the modal analysis and health monitoring community for more than a decade: (a) What is the reliability of results from dynamic testing of constructed systems, (b) Can these tests serve for health monitoring of constructed systems? (c) Are there any additional benefits that may be expected from dynamic testing of constructed systems? (d) Best practices, constraints and future developments needed for a reliable implementation of MIMO testing and output-only modal analysis of constructed systems for health monitoring and other reasons

Limitations in structural identification of large constructed structures

Journal of Structural EngineeringThe objective of this paper is to discuss the limitations in structural identification of large constructed structures. These limitations arise due to the geometric complexity, uncertain boundary and continuity conditions, loading environment, and the imperfect knowledge and errors in modeling such large constructed facilities. In this paper, the writers present their studies on developing a mixed microscopic-structural element level three-dimensional finite-element FE modeling of a long-span bridge structure and its structural system identification by integrating various experimental techniques. It is shown that a reasonable level of confidence 50–90% can be achieved with a model that is calibrated using global and local structural monitoring data with a sufficiently high spatial resolution. The reliability of the global attributes, such as boundary and continuity conditions that may be identified and simulated by means of field-calibrated models using only dynamic test results globally calibrated models , may appear to be high as much as 90% . However, the reliability that should be expected for local stress fields is shown to be an entirely different matter, and a calibration based on just dynamic testing would be unable to reveal the confidence in simulated local responses. This is especially true for long-span bridges, because the resolutions of the dynamic test grids are often quite sparse due to the large size of the structures. In this paper, the writers illustrate that the density, modality, and bandwidth of experimental data should be carefully evaluated and matched to the size and complexity of a constructed system before claiming that a FE model is validated. It is also shown that even more than three dozen acceleration measurement points, two dozen strain measurements, and a continuous surveillance of wind and temperature were barely sufficient for a credible structural identification of a long-span bridge