The needs for advanced sensor technologies in risk assessment of civil infrastructures

Fujino, Yozo,Siringoringo, Dionysius M.,Abe, Masato Techno-Press 2009 Smart Structures and Systems, An International Jou Vol.5 No.2

Civil infrastructures are always subjected to various types of hazard and deterioration. These conditions require systematic efforts to assess the exposure and vulnerability of infrastructure, as well as producing strategic countermeasures to reduce the risks. This paper describes the needs for and concept of advanced sensor technologies for risk assessment of civil infrastructure in Japan. Backgrounds of the infrastructure problems such as natural disasters, difficult environment, limited resource for maintenance, and increasing requirement for safety are discussed. The paper presents a concept of risk assessment, which is defined as a combination of hazard and structural vulnerability assessment. An overview of current practices and research activities toward implementing the concept is presented. This includes implementation of structural health monitoring (SHM) systems for environment and natural disaster prevention, improvement of stock management, and prevention of structural failure.

Japan's experience on long-span bridges monitoring

Fujino, Yozo,Siringoringo, Dionysius M.,Abe, Masato Techno-Press 2016 Structural monitoring and maintenance Vol.3 No.3

This paper provides an overview on development of long-span bridges monitoring in Japan, with emphasis on monitoring strategies, types of monitoring system, and effective utilization of monitoring data. Because of severe environment condition such as high seismic activity and strong wind, bridge monitoring systems in Japan historically put more emphasis on structural evaluation against extreme events. Monitoring data were used to verify design assumptions, update specifications, and facilitate the efficacy of vibration control system. These were among the first objectives of instrumentation of long-span bridges in a framework of monitoring system in Japan. Later, monitoring systems were also utilized to evaluate structural performance under various environment and loading conditions, and to detect the possible structural deterioration over the age of structures. Monitoring systems are also employed as the basis of investigation and decision making for structural repair and/or retrofit when required. More recent interest has been to further extend application of monitoring to facilitate operation and maintenance, through rationalization of risk and asset management by utilizing monitoring data. The paper describes strategies and several examples of monitoring system and lessons learned from structural monitoring of long-span bridges in Japan.

The needs for advanced sensor technologies in risk assessment of civil infrastructures

Yozo Fujino,Dionysius M. Siringoringo,Masato Abe 국제구조공학회 2009 Smart Structures and Systems, An International Jou Vol.5 No.2

Civil infrastructures are always subjected to various types of hazard and deterioration. These conditions require systematic efforts to assess the exposure and vulnerability of infrastructure, as well as producing strategic countermeasures to reduce the risks. This paper describes the needs for and concept of advanced sensor technologies for risk assessment of civil infrastructure in Japan. Backgrounds of the infrastructure problems such as natural disasters, difficult environment, limited resource for maintenance, and increasing requirement for safety are discussed. The paper presents a concept of risk assessment, which is defined as a combination of hazard and structural vulnerability assessment. An overview of current practices and research activities toward implementing the concept is presented. This includes implementation of structural health monitoring (SHM) systems for environment and natural disaster prevention, improvement of stock management, and prevention of structural failure.

Dynamic analysis of guideway structures by considering ultra high-speed Maglev train-guideway interaction

Myung-Kwan Song,Yozo Fujino 국제구조공학회 2008 Structural Engineering and Mechanics, An Int'l Jou Vol.29 No.4

In this study, the new three-dimensional finite element analysis model of guideway structures considering ultra high-speed magnetic levitation train-bridge interaction, in which the various improved finite elements are used to model structural members, is proposed. The box-type bridge deck of guideway structures is modeled by Nonconforming Flat Shell finite elements with six DOF (degrees of freedom). The sidewalls on a bridge deck are idealized by using beam finite elements and spring connecting elements. The vehicle model devised for an ultra high-speed Maglev train is employed, which is composed of rigid bodies with concentrated mass. The characteristics of levitation and guidance force, which exist between the super-conducting magnet and guideway, are modeled with the equivalent spring model. By Lagrange’s equations of motion, the equations of motion of Maglev train are formulated. Finally, by deriving the equations of the force acting on the guideway considering Maglev train-bridge interaction, the complete system matrices of Maglev train-guideway structure system are composed.

Dynamic analysis of guideway structures by considering ultra high-speed Maglev train-guideway interaction

Song, Myung-Kwan,Fujino, Yozo Techno-Press 2008 Structural Engineering and Mechanics, An Int'l Jou Vol.29 No.4

In this study, the new three-dimensional finite element analysis model of guideway structures considering ultra high-speed magnetic levitation train-bridge interaction, in which the various improved finite elements are used to model structural members, is proposed. The box-type bridge deck of guideway structures is modeled by Nonconforming Flat Shell finite elements with six DOF (degrees of freedom). The sidewalls on a bridge deck are idealized by using beam finite elements and spring connecting elements. The vehicle model devised for an ultra high-speed Maglev train is employed, which is composed of rigid bodies with concentrated mass. The characteristics of levitation and guidance force, which exist between the super-conducting magnet and guideway, are modeled with the equivalent spring model. By Lagrange's equations of motion, the equations of motion of Maglev train are formulated. Finally, by deriving the equations of the force acting on the guideway considering Maglev train-bridge interaction, the complete system matrices of Maglev train-guideway structure system are composed.

Feedforward actuator controller development using the backward-difference method for real-time hybrid simulation

Brian M. Phillips,Shuta Takada,Yozo Fujino,B.F. Spencer, Jr 국제구조공학회 2014 Smart Structures and Systems, An International Jou Vol.14 No.6

Real-time hybrid simulation (RTHS) has emerged as an important tool for testing large and complex structures with a focus on rate-dependent specimen behavior. Due to the real-time constraints, accurate dynamic control of servo-hydraulic actuators is required. These actuators are necessary to realize the desired displacements of the specimen, however they introduce unwanted dynamics into the RTHS loop. Model-based actuator control strategies are based on linearized models of the servo-hydraulic system, where the controller is taken as the model inverse to effectively cancel out the servo-hydraulic dynamics (i.e., model-based feedforward control). An accurate model of a servo-hydraulic system generally contains more poles than zeros, leading to an improper inverse (i.e., more zeros than poles). Rather than introduce additional poles to create a proper inverse controller, the higher order derivatives necessary for implementing the improper inverse can be calculated from available information. The backward-difference method is proposed as an alternative to discretize an improper continuous time model for use as a feedforward controller in RTHS. This method is flexible in that derivatives of any order can be explicitly calculated such that controllers can be developed for models of any order. Using model-based feedforward control with the backward-difference method, accurate actuator control and stable RTHS are demonstrated using a nine-story steel building model implemented with an MR damper.

Implementation of video motion magnification technique for non-contact operational modal analysis of light poles

Jothi S. Thiyagarajan,Dionysius M. Siringoringo,Samten Wangchuk,Yozo Fujino 국제구조공학회 2021 Smart Structures and Systems, An International Jou Vol.27 No.2

Damages on lights and utility poles mounted on the elevated highway or railway bridges were observed in the past several large earthquakes. The damages could have serious consequences to public safety, travelling vehicles or trains, and nearby properties. A previous study shows that the damages were caused by buckling and yielding of the pole due to excessive response amplification during large earthquake. Such amplification occurs when the bridge's natural frequency is close to the light pole's fundamental frequency. An investigation of the seismic performance of existing light pole mounted on elevated highway bridges is needed to avoid the response amplification. This includes the identification of the light pole's natural frequency and damping ratio. Vibration testing of the light pole using conventional contact sensors individually would require enormous effort and is time-consuming. Moreover, such vibration testing on a highway bridge deck would require traffic disruption to provide access. Video camera-based non-contact vision sensing is seen as a promising alternative to the conventional contact sensors for this purpose. The objective of this paper is to explore the use of non-contact vision sensing for operational modal analysis of light pole on highway viaduct. The phase-based video motion magnification method is implemented to obtain the light pole response in an ambient condition. Using this method, small and invisible displacement is magnified for a certain range of frequency of interest. Based on the magnified video frames, structural displacement is extracted using the image processing technique. The natural frequency and damping ratio of the light pole are estimated using the random decrement technique. The method is verified in a laboratory-scale experiment and implemented to practical field measurements of a light pole on a highway viaduct in Kanagawa, Japan. The results are compared with measurement by Laser Doppler Vibrometer. Both experiments suggest that the method could effectively obtain the natural frequency and damping ratio of the structures under the ambient condition where vibration amplitudes are very small and invisible with reasonable accuracy.

Feedforward actuator controller development using the backward-difference method for real-time hybrid simulation

Phillips, Brian M.,Takada, Shuta,Spencer, B.F. Jr.,Fujino, Yozo Techno-Press 2014 Smart Structures and Systems, An International Jou Vol.14 No.6

Real-time hybrid simulation (RTHS) has emerged as an important tool for testing large and complex structures with a focus on rate-dependent specimen behavior. Due to the real-time constraints, accurate dynamic control of servo-hydraulic actuators is required. These actuators are necessary to realize the desired displacements of the specimen, however they introduce unwanted dynamics into the RTHS loop. Model-based actuator control strategies are based on linearized models of the servo-hydraulic system, where the controller is taken as the model inverse to effectively cancel out the servo-hydraulic dynamics (i.e., model-based feedforward control). An accurate model of a servo-hydraulic system generally contains more poles than zeros, leading to an improper inverse (i.e., more zeros than poles). Rather than introduce additional poles to create a proper inverse controller, the higher order derivatives necessary for implementing the improper inverse can be calculated from available information. The backward-difference method is proposed as an alternative to discretize an improper continuous time model for use as a feedforward controller in RTHS. This method is flexible in that derivatives of any order can be explicitly calculated such that controllers can be developed for models of any order. Using model-based feedforward control with the backward-difference method, accurate actuator control and stable RTHS are demonstrated using a nine-story steel building model implemented with an MR damper.

Reliable multi-hop communication for structural health monitoring

Tomonori Nagayama,Parya Moinzadeh,Kirill Mechitov,Mitsushi Ushita,Noritoshi Makihata,Masataka Ieiri,Gul Agha,Billie F. Spencer, Jr.,Yozo Fujino,Ju-Won Seo 국제구조공학회 2010 Smart Structures and Systems, An International Jou Vol.6 No.5

Wireless smart sensor networks (WSSNs) have been proposed by a number of researchers to evaluate the current condition of civil infrastructure, offering improved understanding of dynamic response through dense instrumentation. As focus moves from laboratory testing to full-scale implementation, the need for multi-hop communication to address issues associated with the large size of civil infrastructure and their limited radio power has become apparent. Multi-hop communication protocols allow sensors to cooperate to reliably deliver data between nodes outside of direct communication range. However, application specific requirements, such as high sampling rates, vast amounts of data to be collected, precise internodal synchronization, and reliable communication, are quite challenging to achieve with generic multi-hop communication protocols. This paper proposes two complementary reliable multi-hop communication solutions for monitoring of civil infrastructure. In the first approach, termed herein General Purpose Multi-hop (GPMH), the wide variety of communication patterns involved in structural health monitoring, particularly in decentralized implementations, are acknowledged to develop a flexible and adaptable any-to-any communication protocol. In the second approach, termed herein Single-Sink Multi-hop (SSMH), an efficient many-to-one protocol utilizing all available RF channels is designed to minimize the time required to collect the large amounts of data generated by dense arrays of sensor nodes. Both protocols adopt the Ad-hoc On-demand Distance Vector (AODV) routing protocol, which provides any-to-any routing and multi-cast capability, and supports a broad range of communication patterns. The proposed implementations refine the routing metric by considering the stability of links, exclude functionality unnecessary in mostly-static WSSNs, and integrate a reliable communication layer with the AODV protocol. These customizations have resulted in robust realizations of multi-hop reliable communication that meet the demands of structural health monitoring.

Reliable multi-hop communication for structural health monitoring

Nagayama, Tomonori,Moinzadeh, Parya,Mechitov, Kirill,Ushita, Mitsushi,Makihata, Noritoshi,Ieiri, Masataka,Agha, Gul,Spencer, Billie F. Jr.,Fujino, Yozo,Seo, Ju-Won Techno-Press 2010 Smart Structures and Systems, An International Jou Vol.6 No.5

Wireless smart sensor networks (WSSNs) have been proposed by a number of researchers to evaluate the current condition of civil infrastructure, offering improved understanding of dynamic response through dense instrumentation. As focus moves from laboratory testing to full-scale implementation, the need for multi-hop communication to address issues associated with the large size of civil infrastructure and their limited radio power has become apparent. Multi-hop communication protocols allow sensors to cooperate to reliably deliver data between nodes outside of direct communication range. However, application specific requirements, such as high sampling rates, vast amounts of data to be collected, precise internodal synchronization, and reliable communication, are quite challenging to achieve with generic multi-hop communication protocols. This paper proposes two complementary reliable multi-hop communication solutions for monitoring of civil infrastructure. In the first approach, termed herein General Purpose Multi-hop (GPMH), the wide variety of communication patterns involved in structural health monitoring, particularly in decentralized implementations, are acknowledged to develop a flexible and adaptable any-to-any communication protocol. In the second approach, termed herein Single-Sink Multi-hop (SSMH), an efficient many-to-one protocol utilizing all available RF channels is designed to minimize the time required to collect the large amounts of data generated by dense arrays of sensor nodes. Both protocols adopt the Ad-hoc On-demand Distance Vector (AODV) routing protocol, which provides any-to-any routing and multi-cast capability, and supports a broad range of communication patterns. The proposed implementations refine the routing metric by considering the stability of links, exclude functionality unnecessary in mostly-static WSSNs, and integrate a reliable communication layer with the AODV protocol. These customizations have resulted in robust realizations of multi-hop reliable communication that meet the demands of structural health monitoring.