Shinae Jang - Academia.edu (original) (raw)

Papers by Shinae Jang

As civil infrastructure continues to age, the extension of service life has become a financially ... more As civil infrastructure continues to age, the extension of service life has become a financially attractive solution due to cost savings on reconstruction projects. Efforts to increase the service life of structures include nondestructive evaluation (NDE) and structural health monitoring (SHM) techniques. Nonetheless, visual inspection is more frequently used due to high equipment cost from other techniques and federal biennial inspection requirement. Recently, low-cost Radio Frequency Identification Devices (RFID) have drawn attention for crack monitoring; however, it was yet to be implemented in the field. This paper presents a crack monitoring algorithm using a developed RFID-based sensing system employing machine learning under temperature variations for field implementation. Two reinforced concrete buildings were used as testbeds: a parking garage, and a residential building with crumbling foundation phenomenon. An Artificial Neural Network (ANN)-based crack monitoring architec...

Many bridges in the nation’s transportation infrastructure network have been found to be structur... more Many bridges in the nation’s transportation infrastructure network have been found to be structurally deficient. In face of a natural or man-made disaster, this poses a serious threat to the execution of emergency respondent logistics, as the failure of such structures could disconnect communities from the necessary provisions and services that must remain accessible after a disaster. To predict such an eventuality, dependable information on structural status for decision-making can be obtained from structural health monitoring (SHM) systems. However, the avoidance of such a situation is preferred. Structural control systems offer an option to improve structural response during extreme loading events. To this date, some bridges have been instrumented with SHM and control systems that operate simultaneously, but independently without using the information that each provides to enhance operational efficiency in the other. If the information on structural status provided by an SHM syst...

Sensors, 2019

Ultra-high-performance concrete (UHPC) is a novel material with multiple known uses and many stil... more Ultra-high-performance concrete (UHPC) is a novel material with multiple known uses and many still yet to be discovered. Recently, the use of encasing welded shear studs in UHPC on the web of corroded steel beams was developed. This creates a bearing force transfer mechanism to bypass the corroded web plate. This new material and its uses come with many uncertainties in the short and long term. Structural health monitoring (SHM) can be a tool to observe the development. Specifically, radio frequency technology (RFID) can be used. RFID has existed commercially since the 1960s and has been used as a crack sensor before, but never with UHPC. RFID-based crack sensing is being used to monitor the UHPC retrofit. A crack is simulated on the UHPC specimen and then a commercial, low cost tag is secured. Using backscatter power, the tag reads the crack existence and its increasing volume with every new damage stage. Using a damage index, comparing the uncracked and each cracked stage, this me...

Advances in Structural Engineering, 2019

After an explosion, determining the remaining capacity of a structure to resist a progressive col... more After an explosion, determining the remaining capacity of a structure to resist a progressive collapse can provide valuable information for emergency operations and decision makers. Condition assessments after a blast are commonly performed with a visual inspection. However, visual inspections can be time-consuming and involve putting additional personnel into harm’s way. Analytical blast analyses can estimate a structures post-blast condition, but to achieve a high level of accuracy these analyses can be time-consuming and require information regarding the blast event which may not be available at the time. This presents a need for a threat independent post-blast analysis method, which can assess for the post-blast structural condition without requiring personnel to enter the structure. The alternate path method has been used to design buildings to resist a progressive collapse; however, it does not incorporate damage outside of element failure making it unsuitable for post-blast c...

Structural Control and Health Monitoring, 2016

After hazardous events, it is important to be able to quickly identify the remaining stiffness of... more After hazardous events, it is important to be able to quickly identify the remaining stiffness of affected structures for condition evaluation. Model updating can be used to update structural models to reflect current conditions based upon experimental measurements. Direct model updating is a simple and quick method of damage detection, but does not guarantee physical relevance. Least-squares optimization can be used to accurately identify damage with physical relevance, but needs more measurements then updating parameters in order to produce an accurate solution. However, after an extreme event sensors on the structure may be damaged, creating a scenario with limited measurements which can render optimization techniques incapable of assessing the remaining stiffness. To address this issue, this paper proposes a two-phase method to localize and then quantify the remaining stiffness of the structure. Direct model updating with limited measurements is used to localize potential damage to a subset of parameters, and a least-squares optimization using the localized parameters is used to quantify the remaining stiffness in the structure. Numerical simulations using a simplified model based upon the phase I IASCE-ASCE structural health monitoring benchmark problem with missing first floor sensors have been employed to demonstrate, and experiments using a five-story steel frame structure are conducted to validate the methodology.

Journal of the Korean Society for Nondestructive Testing, 2012

Wireless sensor network is one of prospective methods for railway monitoring due to the long-term... more Wireless sensor network is one of prospective methods for railway monitoring due to the long-term operation and low-maintenance performances. How to supply power to the wireless sensor nodes has drawn much attention recently. In railway monitoring, the idea of converting ambient vibration energy from vibration of railway track induced by passing trains to electric energy has made it a potential way for powering the wireless sensor nodes. In this paper, a bimorph cantilever piezoelectric energy harvester was designed based on a single degree-of-freedom model. Experimental test was also performed to validate the design. The first natural frequency of the bimorph piezoelectric energy harvester was decreased from 117.1 Hz to 65.2 Hz by adding 4 gram tip mass to the free end of the 8.6 gram energy harvester. In addition, the power generation of the piezoelectric energy harvester with 4 gram tip mass at resonant frequency was increased from 0.14 mW to 0.74 mW from 2.06 m/s 2 base excitation compared to stand-alone piezoelectric energy harvester without tip mass.

Health Monitoring of Structural and Biological Systems 2017, 2017

Gathering measurements from a structure can be extremely valuable for tasks such as verifying a n... more Gathering measurements from a structure can be extremely valuable for tasks such as verifying a numerical model, or structural health monitoring (SHM) to identify changes in the natural frequencies and mode shapes which can be attributed to changes in the system. In most monitoring applications, the number of potential degrees-of-freedom (DOF) for monitoring greatly outnumbers the available sensors. Optimal sensor placement (OSP) is a field of research into different methods for locating the available sensors to gather the optimal measurements. Three common methods of OSP are the effective independence (EI), effective independence driving point residue (EI-DPR), and modal kinetic energy (MKE) methods. However, comparisons of the different OSP methods for SHM applications are limited. In this paper, a comparison of the performance of the three described OSP methods for parameter estimation is performed. Parameter estimation is implemented using modified parameter localization with direct model updating, and added mass quantification utilizing a genetic algorithm (GA). The quantification of the mass addition, using simulated measurements from the sensor networks developed by each OSP method, is compared to provide an evaluation of each OSP methods capability for parameter estimation applications.

Journal of Civil Structural Health Monitoring, 2016

Detecting structural damage in civil engineering structures has become an increasingly viable opt... more Detecting structural damage in civil engineering structures has become an increasingly viable option for efficient maintenance and management of infrastructures. Vibration-based damage detection methods have been widely used for structural health monitoring. However, those methods may not be effective when modal properties have significant variance under environmental effects, especially severe temperature changes. In this paper, an extended Kalman filter-based artificial neural network (EKFNN) method is developed to eliminate the temperature effects and detect damage for structures equipped with long-term monitoring systems. Based on the vibration acceleration and temperature data obtained from an inservice highway bridge located in Connecticut, United States, the correlations between natural frequencies and temperature are analyzed to select proper input variables for the neural network model. Weights of the neural network are estimated by extended Kalman filter, which is also used to derive the confidence intervals of the natural frequencies to detect the damage. A year-long monitoring data are fed into the developed neural network for the training purpose. To assess the changes of natural frequencies in real structural damages, structural damage scenarios are simulated in the finite element model. Numerical testing results show that the temperature-induced changes in natural frequencies have been considered prior to the establishment of the threshold in the damage warning system, and the simulated damages have been successfully captured. The advantages of EKFNN method are presented through comparing with benchmark multiple linear regressions method, showing the potential of this method for structural health monitoring of highway bridge structures. Keywords Artificial neural network Á Extended Kalman filter Á Bridge monitoring Á Modal analysis Á Structural damage detection Á Temperature effect & Chenhao Jin

Sensors and Smart Structures Technologies for Civil, Mechanical, and Aerospace Systems 2016, 2016

Main tension elements are critical to the overall stability of cable-supported bridges. A dependa... more Main tension elements are critical to the overall stability of cable-supported bridges. A dependable and rapid determination of cable tension is desired to assess the state of a cable-supported bridge and evaluate its operability. A portable smart sensor setup is presented to reduce post-processing time and deployment complexity while reliably determining cable tension using dynamic characteristics extracted from spectral analysis. A self-recording accelerometer is coupled with a single-board microcomputer that communicates wirelessly with a remote host computer. The portable smart sensing device is designed such that additional algorithms, sensors and controlling devices for various monitoring applications can be installed and operated for additional structural assessment. The tension-estimating algorithms are based on taut string theory and expand to consider bending stiffness. The successful combination of cable properties allows the use of a cable’s dynamic behavior to determine tension force. The tension-estimating algorithms are experimentally validated on a through-arch steel bridge subject to ambient vibration induced by passing traffic. The tension estimation is determined in well agreement with previously determined tension values for the structure.

Structural Health Monitoring 2015, 2015

The goal of structural health monitoring is to determine the status of the structure and identify... more The goal of structural health monitoring is to determine the status of the structure and identify the structural damage. Extended Kalman filter (EKF) has shown effective capability to track the structural parameters for civil structures. When structural damage occurs, the estimations of parameters from EKF will deviate from their constant values, and the changes can be observed visually. However, in view of the environmental and operational effects, structural parameters may fluctuate within a normal range, which may result false alarm problems and cause difficulties to observe the structural damage in real time. In this paper, EKF is combined with Statistical Process Control (SPC) to detect the structural damage in real time. Adaptive SPC control limits are derived based on parameter estimation from EKF and updated dynamically in each time step. When structural damage occurs, the estimation of parameters will deviate outside of the control ranges, thus can be captured by the SPC control limits. This approach is tested on a two-story nonlinear hysteretic structure. The numerical testing results demonstrate that the adaptive SPC-based Kalman filter method is capable to identify and track the general changes of structural parameters and detect damage online with high confidence for nonlinear structural dynamic systems. doi: 10.12783/SHM2015/303

SPIE Proceedings, 2015

ABSTRACT Structural health monitoring has drawn significant attention in the past decades with nu... more ABSTRACT Structural health monitoring has drawn significant attention in the past decades with numerous methodologies and applications for civil structural systems. Although many researchers have developed analytical and experimental damage detection algorithms through vibration-based methods, these methods are not widely accepted for practical structural systems because of their sensitivity to uncertain environmental and operational conditions. The primary environmental factor that influences the structural modal properties is temperature. The goal of this article is to analyze the natural frequency-temperature relationships and detect structural damage in the presence of operational and environmental variations using modal-based method. For this purpose, correlations between natural frequency and temperature are analyzed to select proper independent variables and inputs for the multiple linear regression model and neural network model. In order to capture the changes of natural frequency, confidence intervals to detect the damages for both models are generated. A long-term structural health monitoring system was installed on an in-service highway bridge located in Meriden, Connecticut to obtain vibration and environmental data. Experimental testing results show that the variability of measured natural frequencies due to temperature is captured, and the temperature-induced changes in natural frequencies have been considered prior to the establishment of the threshold in the damage warning system. This novel approach is applicable for structural health monitoring system and helpful to assess the performance of the structure for bridge management and maintenance.

Structural Health Monitoring and Inspection of Advanced Materials, Aerospace, and Civil Infrastructure 2015, 2015

After a blast event, it is important to quickly quantify the structural damage for emergency oper... more After a blast event, it is important to quickly quantify the structural damage for emergency operations. In order improve the speed, accuracy, and efficiency of condition assessments after a blast, the authors have previously performed work to develop a methodology for rapid assessment of the structural condition of a building after a blast. The method involved determining a post-event equivalent stiffness matrix using vibration measurements and a finite element (FE) model. A structural model was built for the damaged structure based on the equivalent stiffness, and inter-story drifts from the blast are determined using numerical simulations, with forces determined from the blast parameters. The inter-story drifts are then compared to blast design conditions to assess the structures damage. This method still involved engineering judgment in terms of determining significant frequencies, which can lead to error, especially with noisy measurements. In an effort to improve accuracy and automate the process, this paper will look into a similar method of rapid condition assessment using subspace state-space identification. The accuracy of the method will be tested using a benchmark structural model, as well as experimental testing. The blast damage assessments will be validated using pressure-impulse (P-I) diagrams, which present the condition limits across blast parameters. Comparisons between P-I diagrams generated using the true system parameters and equivalent parameters will show the accuracy of the rapid condition based blast assessments.

International Journal of Advanced Structural Engineering (IJASE), 2015

This article presents an evaluation of the capabilities of wavelet-based methodologies for damage... more This article presents an evaluation of the capabilities of wavelet-based methodologies for damage identification in civil structures. Two different approaches were evaluated: (1) analysis of the structure frequencies evolution by means of the continuous wavelet transform and (2) analysis of the singularities generated in the high frequency response of the structure through the detail functions obtained via fast wavelet transform. The methodologies were evaluated using experimental and numerical simulated data. It was found that the selection of appropriate wavelet parameters is critical for a successful analysis of the signal. Wavelet parameters should be selected based on the expected frequency content of the signal and desired time and frequency resolutions. Identifications of frequency shifts via ridge extraction of the wavelet map were successful in most of the experimental and numerical scenarios investigated. Moreover, the frequency shift can be inferred most of the time but the exact time at which it occurs is not evident. However, this information can be retrieved from the spike location from the Fast Wavelet Transform analysis. Therefore, it is recommended to perform both type of analysis and look at the results together.

Bridge Maintenance, Safety and Management, 2010

Structural health monitoring (SHM) of civil infrastructure using wireless smart sensor networks (... more Structural health monitoring (SHM) of civil infrastructure using wireless smart sensor networks (WSSNs) has received significant public attention in recent years. The benefits of WSSNs are that they are low-cost, easy to install, and provide effective data management via on-board computation. This paper reports on the deployment and evaluation of a state-of-the-art WSSN on the new Jindo Bridge, a cable-stayed bridge in South Korea with a 344-m main span and two 70-m side spans. The central components of the WSSN deployment are the Imote2 smart sensor platforms, a custom-designed multimetric sensor boards, base stations, and software provided by the Illinois Structural Health Monitoring Project (ISHMP) Services Toolsuite. In total, 70 sensor nodes and two base stations have been deployed to monitor the bridge using an autonomous SHM application with excessive wind and vibration triggering the system to initiate monitoring. Additionally, the performance of the system is evaluated in terms of hardware durability, software stability, power consumption and energy harvesting capabilities. The Jindo Bridge SHM system constitutes the largest deployment of wireless smart sensors for civil infrastructure monitoring to date. This deployment demonstrates the strong potential of WSSNs for monitoring of large scale civil infrastructure.

Sensors and Smart Structures Technologies for Civil, Mechanical, and Aerospace Systems 2010, 2010

Wireless Smart Sensor Networks (WSSN) facilitates a new paradigm to structural health monitoring ... more Wireless Smart Sensor Networks (WSSN) facilitates a new paradigm to structural health monitoring (SHM) for civil infrastructure. Conventionally, SHM systems employing wired sensors and central data acquisition have been used to characterize the state of a structure; however, wide-spread implementation has been limited due to difficulties in cabling, high equipment cost, and long setup time. WSSNs offer a unique opportunity

SPIE Proceedings, 2012

Wireless sensor network is one of prospective methods for railway bridge health monitoring. It ha... more Wireless sensor network is one of prospective methods for railway bridge health monitoring. It has drawn much attention due to the long-term operation and low-maintenance performances. However, how to provide power to wireless sensors is a big issue. In railway health monitoring, the idea of converting ambient vibration energy from the vibration of railway track induced by passing train to electric energy has made it an efficient way for powering the wireless sensor networks. In this paper, a bimorph piezoelectric energy harvester from base excitation was investigated in the laboratory, and the energy output of the bimorph energy harvester was predicted by an equivalent single-degree-of-freedom (SDOF) model. Reasonable results have been found between the tested and predicted data. Based on the theoretical model, further works on optimization of the bimorph piezoelectric energy harvester will be performed in future.

Sensors and Smart Structures Technologies for Civil, Mechanical, and Aerospace Systems 2010, 2010

Long-term structural health monitoring (SHM) systems using wireless smart sensors for civil infra... more Long-term structural health monitoring (SHM) systems using wireless smart sensors for civil infrastructures such as cable-stayed bridges has been researched due to its cost-effectiveness and ease of installation. Wireless smart sensors are usually powered by high capacity batteries because they consume low power. However, theses batteries require regular replacements for long-term continuous and stable operation. To overcome this limitation of

Sensors and Smart Structures Technologies for Civil, Mechanical, and Aerospace Systems 2011, 2011

Wireless Smart Sensor Networks (WSSN) facilitates a new paradigm to structural health monitoring ... more Wireless Smart Sensor Networks (WSSN) facilitates a new paradigm to structural health monitoring (SHM) for civil infrastructure. Conventionally, SHM systems employing wired sensors and central data acquisition have been used to characterize the state of a structure; however, wide-spread implementation has been limited due to difficulties in cabling and data management, high equipment cost, and long setup time. WSSNs offer

As civil infrastructure continues to age, the extension of service life has become a financially ... more As civil infrastructure continues to age, the extension of service life has become a financially attractive solution due to cost savings on reconstruction projects. Efforts to increase the service life of structures include nondestructive evaluation (NDE) and structural health monitoring (SHM) techniques. Nonetheless, visual inspection is more frequently used due to high equipment cost from other techniques and federal biennial inspection requirement. Recently, low-cost Radio Frequency Identification Devices (RFID) have drawn attention for crack monitoring; however, it was yet to be implemented in the field. This paper presents a crack monitoring algorithm using a developed RFID-based sensing system employing machine learning under temperature variations for field implementation. Two reinforced concrete buildings were used as testbeds: a parking garage, and a residential building with crumbling foundation phenomenon. An Artificial Neural Network (ANN)-based crack monitoring architec...

Many bridges in the nation’s transportation infrastructure network have been found to be structur... more Many bridges in the nation’s transportation infrastructure network have been found to be structurally deficient. In face of a natural or man-made disaster, this poses a serious threat to the execution of emergency respondent logistics, as the failure of such structures could disconnect communities from the necessary provisions and services that must remain accessible after a disaster. To predict such an eventuality, dependable information on structural status for decision-making can be obtained from structural health monitoring (SHM) systems. However, the avoidance of such a situation is preferred. Structural control systems offer an option to improve structural response during extreme loading events. To this date, some bridges have been instrumented with SHM and control systems that operate simultaneously, but independently without using the information that each provides to enhance operational efficiency in the other. If the information on structural status provided by an SHM syst...

Sensors, 2019

Ultra-high-performance concrete (UHPC) is a novel material with multiple known uses and many stil... more Ultra-high-performance concrete (UHPC) is a novel material with multiple known uses and many still yet to be discovered. Recently, the use of encasing welded shear studs in UHPC on the web of corroded steel beams was developed. This creates a bearing force transfer mechanism to bypass the corroded web plate. This new material and its uses come with many uncertainties in the short and long term. Structural health monitoring (SHM) can be a tool to observe the development. Specifically, radio frequency technology (RFID) can be used. RFID has existed commercially since the 1960s and has been used as a crack sensor before, but never with UHPC. RFID-based crack sensing is being used to monitor the UHPC retrofit. A crack is simulated on the UHPC specimen and then a commercial, low cost tag is secured. Using backscatter power, the tag reads the crack existence and its increasing volume with every new damage stage. Using a damage index, comparing the uncracked and each cracked stage, this me...

Advances in Structural Engineering, 2019

After an explosion, determining the remaining capacity of a structure to resist a progressive col... more After an explosion, determining the remaining capacity of a structure to resist a progressive collapse can provide valuable information for emergency operations and decision makers. Condition assessments after a blast are commonly performed with a visual inspection. However, visual inspections can be time-consuming and involve putting additional personnel into harm’s way. Analytical blast analyses can estimate a structures post-blast condition, but to achieve a high level of accuracy these analyses can be time-consuming and require information regarding the blast event which may not be available at the time. This presents a need for a threat independent post-blast analysis method, which can assess for the post-blast structural condition without requiring personnel to enter the structure. The alternate path method has been used to design buildings to resist a progressive collapse; however, it does not incorporate damage outside of element failure making it unsuitable for post-blast c...

Structural Control and Health Monitoring, 2016

After hazardous events, it is important to be able to quickly identify the remaining stiffness of... more After hazardous events, it is important to be able to quickly identify the remaining stiffness of affected structures for condition evaluation. Model updating can be used to update structural models to reflect current conditions based upon experimental measurements. Direct model updating is a simple and quick method of damage detection, but does not guarantee physical relevance. Least-squares optimization can be used to accurately identify damage with physical relevance, but needs more measurements then updating parameters in order to produce an accurate solution. However, after an extreme event sensors on the structure may be damaged, creating a scenario with limited measurements which can render optimization techniques incapable of assessing the remaining stiffness. To address this issue, this paper proposes a two-phase method to localize and then quantify the remaining stiffness of the structure. Direct model updating with limited measurements is used to localize potential damage to a subset of parameters, and a least-squares optimization using the localized parameters is used to quantify the remaining stiffness in the structure. Numerical simulations using a simplified model based upon the phase I IASCE-ASCE structural health monitoring benchmark problem with missing first floor sensors have been employed to demonstrate, and experiments using a five-story steel frame structure are conducted to validate the methodology.

Journal of the Korean Society for Nondestructive Testing, 2012

Wireless sensor network is one of prospective methods for railway monitoring due to the long-term... more Wireless sensor network is one of prospective methods for railway monitoring due to the long-term operation and low-maintenance performances. How to supply power to the wireless sensor nodes has drawn much attention recently. In railway monitoring, the idea of converting ambient vibration energy from vibration of railway track induced by passing trains to electric energy has made it a potential way for powering the wireless sensor nodes. In this paper, a bimorph cantilever piezoelectric energy harvester was designed based on a single degree-of-freedom model. Experimental test was also performed to validate the design. The first natural frequency of the bimorph piezoelectric energy harvester was decreased from 117.1 Hz to 65.2 Hz by adding 4 gram tip mass to the free end of the 8.6 gram energy harvester. In addition, the power generation of the piezoelectric energy harvester with 4 gram tip mass at resonant frequency was increased from 0.14 mW to 0.74 mW from 2.06 m/s 2 base excitation compared to stand-alone piezoelectric energy harvester without tip mass.

Health Monitoring of Structural and Biological Systems 2017, 2017

Gathering measurements from a structure can be extremely valuable for tasks such as verifying a n... more Gathering measurements from a structure can be extremely valuable for tasks such as verifying a numerical model, or structural health monitoring (SHM) to identify changes in the natural frequencies and mode shapes which can be attributed to changes in the system. In most monitoring applications, the number of potential degrees-of-freedom (DOF) for monitoring greatly outnumbers the available sensors. Optimal sensor placement (OSP) is a field of research into different methods for locating the available sensors to gather the optimal measurements. Three common methods of OSP are the effective independence (EI), effective independence driving point residue (EI-DPR), and modal kinetic energy (MKE) methods. However, comparisons of the different OSP methods for SHM applications are limited. In this paper, a comparison of the performance of the three described OSP methods for parameter estimation is performed. Parameter estimation is implemented using modified parameter localization with direct model updating, and added mass quantification utilizing a genetic algorithm (GA). The quantification of the mass addition, using simulated measurements from the sensor networks developed by each OSP method, is compared to provide an evaluation of each OSP methods capability for parameter estimation applications.

Journal of Civil Structural Health Monitoring, 2016

Detecting structural damage in civil engineering structures has become an increasingly viable opt... more Detecting structural damage in civil engineering structures has become an increasingly viable option for efficient maintenance and management of infrastructures. Vibration-based damage detection methods have been widely used for structural health monitoring. However, those methods may not be effective when modal properties have significant variance under environmental effects, especially severe temperature changes. In this paper, an extended Kalman filter-based artificial neural network (EKFNN) method is developed to eliminate the temperature effects and detect damage for structures equipped with long-term monitoring systems. Based on the vibration acceleration and temperature data obtained from an inservice highway bridge located in Connecticut, United States, the correlations between natural frequencies and temperature are analyzed to select proper input variables for the neural network model. Weights of the neural network are estimated by extended Kalman filter, which is also used to derive the confidence intervals of the natural frequencies to detect the damage. A year-long monitoring data are fed into the developed neural network for the training purpose. To assess the changes of natural frequencies in real structural damages, structural damage scenarios are simulated in the finite element model. Numerical testing results show that the temperature-induced changes in natural frequencies have been considered prior to the establishment of the threshold in the damage warning system, and the simulated damages have been successfully captured. The advantages of EKFNN method are presented through comparing with benchmark multiple linear regressions method, showing the potential of this method for structural health monitoring of highway bridge structures. Keywords Artificial neural network Á Extended Kalman filter Á Bridge monitoring Á Modal analysis Á Structural damage detection Á Temperature effect & Chenhao Jin

Sensors and Smart Structures Technologies for Civil, Mechanical, and Aerospace Systems 2016, 2016

Main tension elements are critical to the overall stability of cable-supported bridges. A dependa... more Main tension elements are critical to the overall stability of cable-supported bridges. A dependable and rapid determination of cable tension is desired to assess the state of a cable-supported bridge and evaluate its operability. A portable smart sensor setup is presented to reduce post-processing time and deployment complexity while reliably determining cable tension using dynamic characteristics extracted from spectral analysis. A self-recording accelerometer is coupled with a single-board microcomputer that communicates wirelessly with a remote host computer. The portable smart sensing device is designed such that additional algorithms, sensors and controlling devices for various monitoring applications can be installed and operated for additional structural assessment. The tension-estimating algorithms are based on taut string theory and expand to consider bending stiffness. The successful combination of cable properties allows the use of a cable’s dynamic behavior to determine tension force. The tension-estimating algorithms are experimentally validated on a through-arch steel bridge subject to ambient vibration induced by passing traffic. The tension estimation is determined in well agreement with previously determined tension values for the structure.

Structural Health Monitoring 2015, 2015

The goal of structural health monitoring is to determine the status of the structure and identify... more The goal of structural health monitoring is to determine the status of the structure and identify the structural damage. Extended Kalman filter (EKF) has shown effective capability to track the structural parameters for civil structures. When structural damage occurs, the estimations of parameters from EKF will deviate from their constant values, and the changes can be observed visually. However, in view of the environmental and operational effects, structural parameters may fluctuate within a normal range, which may result false alarm problems and cause difficulties to observe the structural damage in real time. In this paper, EKF is combined with Statistical Process Control (SPC) to detect the structural damage in real time. Adaptive SPC control limits are derived based on parameter estimation from EKF and updated dynamically in each time step. When structural damage occurs, the estimation of parameters will deviate outside of the control ranges, thus can be captured by the SPC control limits. This approach is tested on a two-story nonlinear hysteretic structure. The numerical testing results demonstrate that the adaptive SPC-based Kalman filter method is capable to identify and track the general changes of structural parameters and detect damage online with high confidence for nonlinear structural dynamic systems. doi: 10.12783/SHM2015/303

SPIE Proceedings, 2015

ABSTRACT Structural health monitoring has drawn significant attention in the past decades with nu... more ABSTRACT Structural health monitoring has drawn significant attention in the past decades with numerous methodologies and applications for civil structural systems. Although many researchers have developed analytical and experimental damage detection algorithms through vibration-based methods, these methods are not widely accepted for practical structural systems because of their sensitivity to uncertain environmental and operational conditions. The primary environmental factor that influences the structural modal properties is temperature. The goal of this article is to analyze the natural frequency-temperature relationships and detect structural damage in the presence of operational and environmental variations using modal-based method. For this purpose, correlations between natural frequency and temperature are analyzed to select proper independent variables and inputs for the multiple linear regression model and neural network model. In order to capture the changes of natural frequency, confidence intervals to detect the damages for both models are generated. A long-term structural health monitoring system was installed on an in-service highway bridge located in Meriden, Connecticut to obtain vibration and environmental data. Experimental testing results show that the variability of measured natural frequencies due to temperature is captured, and the temperature-induced changes in natural frequencies have been considered prior to the establishment of the threshold in the damage warning system. This novel approach is applicable for structural health monitoring system and helpful to assess the performance of the structure for bridge management and maintenance.

Structural Health Monitoring and Inspection of Advanced Materials, Aerospace, and Civil Infrastructure 2015, 2015

After a blast event, it is important to quickly quantify the structural damage for emergency oper... more After a blast event, it is important to quickly quantify the structural damage for emergency operations. In order improve the speed, accuracy, and efficiency of condition assessments after a blast, the authors have previously performed work to develop a methodology for rapid assessment of the structural condition of a building after a blast. The method involved determining a post-event equivalent stiffness matrix using vibration measurements and a finite element (FE) model. A structural model was built for the damaged structure based on the equivalent stiffness, and inter-story drifts from the blast are determined using numerical simulations, with forces determined from the blast parameters. The inter-story drifts are then compared to blast design conditions to assess the structures damage. This method still involved engineering judgment in terms of determining significant frequencies, which can lead to error, especially with noisy measurements. In an effort to improve accuracy and automate the process, this paper will look into a similar method of rapid condition assessment using subspace state-space identification. The accuracy of the method will be tested using a benchmark structural model, as well as experimental testing. The blast damage assessments will be validated using pressure-impulse (P-I) diagrams, which present the condition limits across blast parameters. Comparisons between P-I diagrams generated using the true system parameters and equivalent parameters will show the accuracy of the rapid condition based blast assessments.

International Journal of Advanced Structural Engineering (IJASE), 2015

This article presents an evaluation of the capabilities of wavelet-based methodologies for damage... more This article presents an evaluation of the capabilities of wavelet-based methodologies for damage identification in civil structures. Two different approaches were evaluated: (1) analysis of the structure frequencies evolution by means of the continuous wavelet transform and (2) analysis of the singularities generated in the high frequency response of the structure through the detail functions obtained via fast wavelet transform. The methodologies were evaluated using experimental and numerical simulated data. It was found that the selection of appropriate wavelet parameters is critical for a successful analysis of the signal. Wavelet parameters should be selected based on the expected frequency content of the signal and desired time and frequency resolutions. Identifications of frequency shifts via ridge extraction of the wavelet map were successful in most of the experimental and numerical scenarios investigated. Moreover, the frequency shift can be inferred most of the time but the exact time at which it occurs is not evident. However, this information can be retrieved from the spike location from the Fast Wavelet Transform analysis. Therefore, it is recommended to perform both type of analysis and look at the results together.

Bridge Maintenance, Safety and Management, 2010

Structural health monitoring (SHM) of civil infrastructure using wireless smart sensor networks (... more Structural health monitoring (SHM) of civil infrastructure using wireless smart sensor networks (WSSNs) has received significant public attention in recent years. The benefits of WSSNs are that they are low-cost, easy to install, and provide effective data management via on-board computation. This paper reports on the deployment and evaluation of a state-of-the-art WSSN on the new Jindo Bridge, a cable-stayed bridge in South Korea with a 344-m main span and two 70-m side spans. The central components of the WSSN deployment are the Imote2 smart sensor platforms, a custom-designed multimetric sensor boards, base stations, and software provided by the Illinois Structural Health Monitoring Project (ISHMP) Services Toolsuite. In total, 70 sensor nodes and two base stations have been deployed to monitor the bridge using an autonomous SHM application with excessive wind and vibration triggering the system to initiate monitoring. Additionally, the performance of the system is evaluated in terms of hardware durability, software stability, power consumption and energy harvesting capabilities. The Jindo Bridge SHM system constitutes the largest deployment of wireless smart sensors for civil infrastructure monitoring to date. This deployment demonstrates the strong potential of WSSNs for monitoring of large scale civil infrastructure.

Sensors and Smart Structures Technologies for Civil, Mechanical, and Aerospace Systems 2010, 2010

Wireless Smart Sensor Networks (WSSN) facilitates a new paradigm to structural health monitoring ... more Wireless Smart Sensor Networks (WSSN) facilitates a new paradigm to structural health monitoring (SHM) for civil infrastructure. Conventionally, SHM systems employing wired sensors and central data acquisition have been used to characterize the state of a structure; however, wide-spread implementation has been limited due to difficulties in cabling, high equipment cost, and long setup time. WSSNs offer a unique opportunity

SPIE Proceedings, 2012

Wireless sensor network is one of prospective methods for railway bridge health monitoring. It ha... more Wireless sensor network is one of prospective methods for railway bridge health monitoring. It has drawn much attention due to the long-term operation and low-maintenance performances. However, how to provide power to wireless sensors is a big issue. In railway health monitoring, the idea of converting ambient vibration energy from the vibration of railway track induced by passing train to electric energy has made it an efficient way for powering the wireless sensor networks. In this paper, a bimorph piezoelectric energy harvester from base excitation was investigated in the laboratory, and the energy output of the bimorph energy harvester was predicted by an equivalent single-degree-of-freedom (SDOF) model. Reasonable results have been found between the tested and predicted data. Based on the theoretical model, further works on optimization of the bimorph piezoelectric energy harvester will be performed in future.

Sensors and Smart Structures Technologies for Civil, Mechanical, and Aerospace Systems 2010, 2010

Long-term structural health monitoring (SHM) systems using wireless smart sensors for civil infra... more Long-term structural health monitoring (SHM) systems using wireless smart sensors for civil infrastructures such as cable-stayed bridges has been researched due to its cost-effectiveness and ease of installation. Wireless smart sensors are usually powered by high capacity batteries because they consume low power. However, theses batteries require regular replacements for long-term continuous and stable operation. To overcome this limitation of

Sensors and Smart Structures Technologies for Civil, Mechanical, and Aerospace Systems 2011, 2011

Wireless Smart Sensor Networks (WSSN) facilitates a new paradigm to structural health monitoring ... more Wireless Smart Sensor Networks (WSSN) facilitates a new paradigm to structural health monitoring (SHM) for civil infrastructure. Conventionally, SHM systems employing wired sensors and central data acquisition have been used to characterize the state of a structure; however, wide-spread implementation has been limited due to difficulties in cabling and data management, high equipment cost, and long setup time. WSSNs offer