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Developments and applications of structural health monitoring (SHM) systems have become active particularily for long-span
bridges in Korea. They are composed of sensors, data acquisition system, data transmission system, information processing,
damage assessment, and information management. In this paper, current status of research and application...
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Citations
... Therefore, real-time monitoring of the cable force during the construction and service periods is essential to ensure the safety of the cable structure. To avoid accidents, Structural Health Monitoring (SHM) for monitoring and evaluation of completed cable structures has emerged and has been implemented worldwide (BrownjohnPines and Aktan, 2002;Yun et al., 2003;, 2007). According to current research data, cable force detection methods mainly include the magnetic flux method (Cappello et al., 2018;Duan et al., 2015;Fabo et al., 2002), the strain gauge method (Volokhov et al., 2016;Moradi and Sivoththaman, 2013) and the vibration method (Furukawa et al., 2022;Ma et al., 2021;Kangas et al., 2012;Fang and Wang, 2012;Mehrabi, 2006). ...
As light and efficient large-span space structures, beam string structures have been widely used since the 1980s. Within them, cables are the main force-bearing component; their level of tension determines the overall stiffness, performance and structural safety of the beam string structures. Real-time monitoring of the cable force during the construction and service periods is an important and effective measure to ensure the safety of the cable structure. At present, the vibration method is widely used in nearly all common engineering practices for cable force identification/monitoring because of its simplicity and efficiency. However, the vibration of the cable segment will be affected by the whole structure, so the cable force-frequency relationship based on the simple single cable model cannot meet the accuracy requirement of cable force identification of the beam string structure. Therefore, in this paper, through finite element simulation and theoretical analysis, a three-stage criterion is proposed to develop a new method for obtaining the local modal information of the tensioned cable segment where the influence of the overall structure is considered. The new method’s performance was compared with the results obtained by the vibration method according to the single-cable model assumption, and the design values of the cable forces. The magnitude of the error in the identification of the tension force of the beam string structure according to the single-cable model was studied to provide a correction method, so that the single-cable model assumption can be used to improve the measuring efficiency and ensure the solution accuracy. The numerical results show the effectiveness of the proposed method. The work of this paper provides a new approach for improving the identification accuracy of the vibration method of a complex cable system such as the beam string structure and is a useful discussion on the vibration method of complex cable systems.
... Civil structures during their useful life are exposed to different conditions that can affect their correct performance, such as weather conditions, high operating temperatures, seismic activities, overloads, etc., which can cause early deterioration. These circumstances have aroused interest around the world in the development of methodologies and techniques to detect unforeseen damage that can put human lives at risk [1,2]. ...
A data-driven-based methodology for SHM in reinforced concrete structures using embedded fiber optic sensors and pattern recognition techniques is presented. A prototype of a reinforced concrete structure was built and instrumented in a novel fashion with FBGs bonded directly to the reinforcing steel bars, which, in turn, were embedded into the concrete structure. The structure was dynamically loaded using a shaker. Superficial positive damages were induced using bonded thin steel plates. Data for pristine and damaged states were acquired. Classifiers based on Mahalanobis’ distance of the covariance data matrix were developed for both supervised and unsupervised pattern recognition with an accuracy of up to 98%. It was demonstrated that the proposed sensing scheme in conjunction with the developed supervised and unsupervised pattern recognition techniques allows the detection of slight stiffness changes promoted by damages, even when strains are very small and the changes of these associated with the damage occurrence may seem negligible.
... In recent years, a great deal of research has focused on the structural health monitoring (SHM) technique [1][2][3][4]. To ensure structural safety during its service life, the SHM system (SHMS) has been designed and implemented on many important bridges in the United States [5][6][7], Europe [8][9][10][11][12], Canada [13,14], Korea [15][16][17], and Japan [18][19][20]. In China, the SHMS has been implemented on a large number of long-span bridges [21][22][23][24]. ...
The Junshan Yangtze River Bridge, built in Wuhan, China in 2001, is a steel box girder cable-stayed bridge with a main span of 460m. Due to decades of service, the bridge suffered gradual degradation and some damage. Structural health monitoring has attracted worldwide attention due to its capacity of monitoring structural damage, assisting maintenance and management, and ensuring safe operation of bridges. To monitor the performance status of bridges and generate a timely safety alarm, an integrated health monitoring system has been designed and implemented on bridges. This paper provides a thorough account of the monitoring system used at the Junshan Yangtze River Bridge. It mainly focuses on the selection of monitoring variables and arrangement of sensor points, the data collection and transmission system, the data storage and management strategy, and the user interface system. All kinds of monitoring data collected under daily operation, such as vehicle load, deflection, displacement, and cable tension, are analysed. Monitoring data for an extreme condition, which involves two heavy trucks of 178 tons moving across the bridge, are also analysed. The results indicate that the monitoring system works well and that some local welded joints may experience fatigue damage.
... In recent years, built-in structural health monitoring (SHM) systems have been crucial for the long-term monitoring of large-scale civil infrastructures (Andersen and Pedersen 1994;Ko and Ni 2005;Koh et al. 2003;Lau et al. 2000;Pines and Aktan 2002;Sumitoro et al. 2001;Yun et al. 2003). When combined with continuous monitoring of built-in SHM systems, these systems allow assessment of structural conditions using structural responses as well as tracking of the modal parameters of structures without user intervention. ...
The recent development of automated operational modal analysis (OMA) has enabled the modal tracking of environmental and operational conditions. Variations in these conditions have prevented investigations into the long-term characteristics of the damping ratio due to its inherently high degree of scattering. In this study, the long-term damping characteristics of a twin cable-stayed bridge under environmental and operational variations were investigated. A displacement reconstruction algorithm was applied to resolve the model-order dependency in OMA-based damping estimates. In order to automatically establish groups of modal estimates, optimal parameters for a density-based unsupervised clustering algorithm were proposed on the basis of gaps between target modal frequencies. The proposed clustering parameters were first validated by comparing the clustering results with those of manually determined ground truth classes. Next, the applicability of the clustering parameters for long-term damping estimation was demonstrated by quantifying the dispersion of modal estimates in each cluster. Subsequently, the framework was applied to 2.5 years of monitoring data to evaluate the long-term damping characteristics of the twin cable-stayed bridge that is often subjected to high variations in environmental and operational conditions. The following aspects are mainly discussed: (1) seasonal fluctuation in long-term damping ratios; (2) the effect that aerodynamic interference exerts on variations in the dynamic characteristics; and (3) the amplitude dependency of the damping ratio. The probability distribution of the modal damping ratio is provided based on the statistical analysis of reliable modal damping ratios.
... In recent years, built-in structural health monitoring (SHM) systems have been crucial for the long-term monitoring of large-scale civil infrastructures (Andersen and Pedersen 1994;Ko and Ni 2005;Koh et al. 2003;Lau et al. 2000;Pines and Aktan 2002;Sumitoro et al. 2001;Yun et al. 2003). When combined with continuous monitoring of built-in SHM systems, these systems allow assessment of structural conditions using structural responses as well as tracking of the modal parameters of structures without user intervention. ...
The recent development of automated operational modal analysis (OMA) has enabled the modal tracking of environmental and operational conditions. Variations in these conditions have prevented investigations into the long-term characteristics of the damping ratio due to its inherently high degree of scattering. In this study the long-term damping characteristics of a twin cable-stayed bridge under environmental and operational variations was investigated. A displacement reconstruction algorithm was applied to resolve the model-order dependency in OMA-based damping estimates. In order to automatically establish groups of modal estimates, optimal parameters for a density-based unsupervised clustering algorithm were proposed on the basis of gaps between target modal frequencies. The proposed clustering parameters were first validated by comparing the clustering results with those of manually determined ground-truth classes. Next, the applicability of the clustering parameters for long-term damping estimation was demonstrated by quantifying the dispersion of modal estimates in each cluster. Subsequently, the framework was applied to 2.5 years of monitoring data to evaluate the long-term damping characteristics of the twin cable-stayed bridge that is often subjected to high variations in environmental and operational conditions. The following aspects are mainly discussed: (1) seasonal fluctuation in long-term damping ratios; (2) the effect that aerodynamic interference exerts on variations in the dynamic characteristics; and, (3) the amplitude dependency of the damping ratio. The probability distribution of the modal damping ratio is provided based on statistical analysis of reliable modal damping ratios.
... However, as time goes on, operation security and reliability of bridges become an important problem one has to face. To avoid serious accidents, structural health monitoring (SHM) for surveillance, evaluation and assessment of built bridges emerges at the same time, which has been implemented all around the world [6][7][8][9][10][11]. The existing structural health monitoring system of cable-stayed bridge has been overviewed, including various monitoring technologies, dynamic identification, damage diagnosis and applications [12][13][14]. ...
Cables as the crucial components, its inspection is the key problem to ensure the safety of cable-stayed bridge. Study of the monitoring methods of cable tension has practical meaning to bridge stability. Firstly, this paper summarized static and dynamic theory of cables. Then, the traditional and innovative monitoring methods of cable force are analyzed, especially the recent emerging intelligent methods. At the end of the paper, a conclusion is provided for the future development of cable-stayed bridges.
... Platforms enabling wireless sensor networks [23][24][25] such as Imote2 wireless sensor platform and others have been successfully developed, implemented, and are continuously improved [26][27][28][29]. Continued effort has been invested in this area with large-scale SHMs and dense instrumentations [30][31][32]. Advances in long-term SHM applications with permanent installations on operating bridges including energy harvesting methods such as solar-powered wireless sensor networks has been investigated [14,[32][33][34]. Many examples can be found in wireless sensing systems used for structural assessment and health monitoring. ...
The use of wireless sensors for bridge assessment has been investigated extensively in the past decades. However, in most field applications, current sensors and sensing systems still rely on wired connectivity for communication and power. This is the case even though tethered sensors require extensive cabling throughout a structure resulting in long installation processes, and their maintenance may increase the total cost of Structural Health Monitoring systems and impede their broader use, especially when rapid infrastructure assessment is needed. One possible explanation of this slow adoption of wireless sensors is the use of sensing units that have not been tested for decades as their wired counterparts. This paper presents a suite of wireless sensors that were developed through the transformation of established wired sensors into wireless units. The objective was to explore whether it was possible to transform such wired sensors into wireless units and then confirm successful transformation with laboratory and field applications. The sensors presented here focus on accurate measurements of displacement, strain, and acceleration with units that are rugged, have a long service life and are used primarily for rapid structural assessment. With this transformation, the authors wanted to accomplish the goal of rapid installation and sensing reuse, and achieve accurate wireless measurements guaranteed by the wired sensors of established sensing vendors. In this study, the wireless sensors were tested first in laboratory conditions along with wired sensors for comparison and then were successfully tested in the field.
... Different design codes specify the service life of these structures to be from 50 to 100 years (AASHTO, 2010;ACI 318-14, 2014;EN1992-1-1, 2004. However, these structures, especially bridges, are constantly exposed to environmental (weather conditions, wind loads, seismic activity, increase in traffic frequency) and man-made hazards; and are deteriorating before their intended design life (Gordan, Razak, Ismail, & Ghaedi, 2017;Yun, Lee, Kim, & Kim, 2003). Despite the advancements in the design code procedures, the environmental changes, increasing service loads, and the unpredictable nature of the natural hazards, have a direct impact on the serviceability of the existing structures. ...
This study presents a simulation-based method for damage detection in reinforced concrete beam-type structures. Reinforced concrete bridges are constantly exposed to dynamic loading, thus leading to deterioration before their design life. A novel damage assessment procedure has been presented, which uses the changes in non-linear vibration characteristics from computational model for damage assessment. A constitutive model is proposed, the parameters of which can be developed from compressive strength from laboratory test, and implemented in FE modelling of an RC beam. Incremental static damage is simulated in the beam, after which the non-linear behaviour is detected using harmonic excitation. The non-linear behaviour from simulation is characterised and used in proposing a damage detection method that does not rely on the baseline data of the structure. The methodology is validated experimentally and compared with conventional linear frequency-shift-based damage detection method. Resultantly, the proposed method is simple, computationally efficient, shows good agreement with the published studies on cracked vibration behaviour and has promising prospects in addressing inverse engineering problem in structural health monitoring of RC structures.
... RC structures are comparatively more economical, stable, serviceable and durable. However, these structures are constantly exposed to environmental loads such as weather fluctuations, wind loads, temperature gradients, seismic activity, increase in traffic frequency as well as man-made hazards [19] and are deteriorating before their intended design life [20]. The main reasons for the deterioration of structures are due to the existence of outdated design codes, environmental changes, increasing service loads, and the unpredictable nature of natural hazards. ...
... The acoustic emission damage detection technique has shown good prospects in online damage detection [36], but the weak signals can easily be influenced by noise. Further details of these techniques can be found elsewhere [20,37]. ...
Reinforced concrete construction is the most popular construction material so far and has significantly contributed to the constantly expanding infrastructure. Nonetheless, this material suffers from damage due to external loadings caused by temperature fluctuations, and dynamic and static loading. Many approaches have been investigated to detect, repair, and prevent such damage. Out of all the approaches, vibration-based damage detection approaches are the most popular approaches because of the easy acquisition of vibration characteristics and global information on structural conditions. However, these approaches have not been successfully implemented because of inadequacies in constitutive modeling, dynamic behavior modeling and various other constraints. This study presents a review with emphasis on concrete modeling that addresses the constraints in the vibration modeling by incorporating the nonlinear behavior. To serve this purpose, a damage assessment methodology is proposed which attempts to address constraints like model updating, sensitivity to damage, environmental influences and most importantly, eliminating the baseline data. The method has been briefly explained step-by-step by modeling an RC beam and validating it by laboratory testing. The contribution of this study is to review the latest developments on nonlinear model-based methods in the damage assessment of constructed systems, identify the constraints in field applications and attempt to address these issues by proposing a damage assessment methodology.
... SHM technology is employed for various applications worldwide. For example, long-term monitoring systems have been implemented to monitor large structures in various countries such as Europe [3e5], the United States [6,7], Canada [8,9], Japan [10,11], Korea [12,13], China [14e16], and other countries [17e19]. Development of SHM helps in detecting damage and analyzing strategies, which further helps to increase the service life of engineering structures or components by avoiding their failure [20]. ...
In this chapter, benefits of implementation of SHM, such as enhancement of public safety, early risk detection, improvement in the life span of the structure, and decrease in the capital expenditures involved, are discussed. The state of the practice in bridge monitoring systems for some famous bridgeslike the Tsing Ma Bridge, Commodore Barry Bridge, and Great Belt Bridge have been listed. Factors affecting measurement of data influence the overall analysis and thus the final monitoring results are not obtained accurately. Factors like environmental effects, on-site construction defects, and mixing of data by different monitoring techniques significantly alter the measurement data obtained. Further challenges in SHM due to un-standardized policies are also reviewed. Lastly, advantages of SHM have been explained with the help of some catastrophic disasters due to improper implementation of required SHM techniques.
