Sensors and Smart Structures Technologies for Civil, Mechanical, and Aerospace Systems 2012, 2012
ABSTRACT This paper illustrates an experimental campaign conducted under laboratory conditions on... more ABSTRACT This paper illustrates an experimental campaign conducted under laboratory conditions on a full-scale reinforced concrete three-dimensional frame instrumented with wireless sensors developed within the Memscon project. In particular it describes the assumptions which the experimental campaign was based on, the design of the structure, the laboratory setup and the results of the tests. The aim of the campaign was to validate the performance of Memscon sensing systems, consisting of wireless accelerometers and strain sensors, on a real concrete structure during construction and under an actual earthquake. Another aspect of interest was to assess the effectiveness of the full damage recognition procedure based on the data recorded by the sensors and the reliability of the Decision Support System (DSS) developed in order to provide the stakeholders recommendations for building rehabilitation and the costs of this. With these ends, a Eurocode 8 spectrum-compatible accelerogram with increasing amplitude was applied at the top of an instrumented concrete frame built in the laboratory. MEMSCON sensors were directly compared with wired instruments, based on devices available on the market and taken as references, during both construction and seismic simulation.
Damage Assessment of Structures X, Pts 1 and 2, 2013
ABSTRACT This paper illustrates an application of Bayesian logic to monitoring data analysis and ... more ABSTRACT This paper illustrates an application of Bayesian logic to monitoring data analysis and structural condition state inference. The case study is a 260 m long cable-stayed bridge spanning the Adige River 10 km north of the town of Trento, Italy. This is a statically indeterminate structure, having a composite steel-concrete deck, supported by 12 stay cables. Structural redundancy, possible relaxation losses and an as-built condition differing from design, suggest that long-term load redistribution between cables can be expected. To monitor load redistribution, the owner decided to install a monitoring system which combines built-on-site elasto-magnetic and fiber-optic sensors. In this note, we discuss a rational way to improve the accuracy of the load estimate from the EM sensors taking advantage of the FOS information. More specifically, we use a multi-sensor Bayesian data fusion approach which combines the information from the two sensing systems with the prior knowledge, including design information and the outcomes of laboratory calibration. Using the data acquired to date, we demonstrate that combining the two measurements allows a more accurate estimate of the cable load, to better than 50 kN
ABSTRACT A wireless sensor network is proposed for monitoring buildings to assess earthquake dama... more ABSTRACT A wireless sensor network is proposed for monitoring buildings to assess earthquake damage. The sensor nodes use custom-developed capacitive microelectromechanical systems strain and 3-D acceleration sensors and a low power readout application-specified integrated circuit for a battery life of up to 12 years. The strain sensors are mounted at the base of the building to measure the settlement and plastic hinge activation of the building after an earthquake. They measure periodically or on-demand from the base station. The accelerometers are mounted at every floor of the building to measure the seismic response of the building during an earthquake. They record during an earthquake event using a combination of the local acceleration data and remote triggering from the base station based on the acceleration data from multiple sensors across the building. A low power network architecture was implemented over an 802.15.4 MAC in the 900-MHz band. A custom patch antenna was designed in this frequency band to obtain robust links in real-world conditions. The modules have been validated in a full-scale laboratory setup with simulated earthquakes.
The evaluation of seismic damage is today almost exclusively based on visual inspection, as build... more The evaluation of seismic damage is today almost exclusively based on visual inspection, as building owners are generally reluctant to install permanent sensing systems, due to their high installation, management and maintenance costs. To overcome this limitation, the EU-funded MEMSCON project aims to produce small size sensing nodes for measurement of strain and acceleration, integrating Micro-Electro-Mechanical Systems (MEMS) based sensors and Radio Frequency Identification (RFID) tags in a single package that will be attached to reinforced concrete buildings. To reduce the impact of installation and management, data will be transmitted to a remote base station using a wireless interface. During the project, sensor prototypes were produced by assembling pre-existing components and by developing ex-novo miniature devices with ultra-low power consumption and sensing performance beyond that offered by sensors available on the market. The paper outlines the device operating principles, production scheme and working at both unit and network levels. It also reports on validation campaigns conducted in the laboratory to assess system performance. Accelerometer sensors were tested on a reduced scale metal frame mounted on a shaking table, back to back with reference devices, while strain sensors were embedded in both reduced and full-scale reinforced concrete specimens undergoing increasing deformation cycles up to extensive damage and collapse. The paper assesses the economical sustainability and performance of the sensors developed for the project and discusses their applicability to long-term seismic monitoring.
... Daniele Zonta, Matteo Pozzi and Antonella Colombo, Department of Mechanical and Structural En... more ... Daniele Zonta, Matteo Pozzi and Antonella Colombo, Department of Mechanical and Structural Engineering, University of Trento, via Mesiano 77, 38050 Trento, Italy. Daniele Inaudi and Angelo Figini, Smartec SA, via Pobiette 11, CH-6928 Manno, Switzerland. 471 Page 494. ...
The evaluation of seismic damage is today almost exclusively based on visual inspection, as build... more The evaluation of seismic damage is today almost exclusively based on visual inspection, as building owners are generally reluctant to install permanent sensing systems, due to their high installation, management and maintenance costs. To overcome this limitation, the EU-funded MEMSCON project aims to produce small size sensing nodes for measurement of strain and acceleration, integrating Micro-Electro-Mechanical Systems (MEMS) based sensors and Radio Frequency Identification (RFID) tags in a single package that will be attached to reinforced concrete buildings and will transmit data using a wireless interface. During the first phase of the project completed so far, sensor prototypes were produced by assembling preexisting components. This paper outlines the device operating principles, production scheme and operation at both unit and network levels. It also reports on validation campaigns conducted in the laboratory to assess system performance. Accelerometer sensors were tested on a reduced scale metal frame mounted on a shaking table, while strain sensors were embedded in both reduced and full-scale reinforced concrete specimens undergoing increasing deformation cycles up to extensive damage and collapse. The performance of the sensors developed for the project and their applicability to long-term seismic monitoring are discussed.
Motivated by the preservation of an artistic treasure, the fresco of the "Cycle of the Months" on... more Motivated by the preservation of an artistic treasure, the fresco of the "Cycle of the Months" on the second floor in an historic tower, Torre Aquila, a wireless sensor network (WSN) has been developed and installed for permanent health monitoring. The monitoring scheme covers both static and dynamic evaluation of the tower structural integrity from local to global scale and consists of 17 nodes, including 2 long length fiber optic sensors (FOS), 3 accelerometers and 12 environmental nodes. The system has been working for 1.5 years and has been debugged and updated both as to hardware and software. This paper focuses mainly on the ambient vibration analysis used to investigate the performance of the sensor nodes and structural properties of the tower. Initial ambient vibration monitoring shows that cyclic environmental factors, such as traffic flow, are not the dominant cause of tower vibration; and the vibration levels of the tower in different axes are not large enough to be a critical issue calling for attention under current conditions. It proves that the WSN is an effective tool, capable of providing information relevant to safety assessment of the tower.
ABSTRACT This paper describes the application of a wireless sensor network (WSN) in Torre Aquila,... more ABSTRACT This paper describes the application of a wireless sensor network (WSN) in Torre Aquila, a 31 meter-tall medieval tower located in the city of Trento (Italy). Special attention was paid to monitoring and preservation of an artistic treasure: the fresco of the “Cycle of the Months ” on the second floor. The various sensors installed include accelerometers, thermometers and strain gauges, arranged to record both structural response and external effects (road traffic vibration, temperature change), in order to real-time calibrate the structural model parameters and to identify any possible occurrence of abnormal situations. Strain sensors include prototypes of new Fiber Optic Sensors (FOS) in view of their long-term stability and durability. Based on the first 8 months of operation in assessing the stability of the tower, the wireless system is seen to be an effective tool thanks to its customized hardware and dedicated software. The whole system is reliable and energy efficient. The comparison between the acquired measurements and simulated numerical results shows good agreement.
Sensors and Smart Structures Technologies for Civil, Mechanical, and Aerospace Systems 2012, 2012
ABSTRACT This paper illustrates an experimental campaign conducted under laboratory conditions on... more ABSTRACT This paper illustrates an experimental campaign conducted under laboratory conditions on a full-scale reinforced concrete three-dimensional frame instrumented with wireless sensors developed within the Memscon project. In particular it describes the assumptions which the experimental campaign was based on, the design of the structure, the laboratory setup and the results of the tests. The aim of the campaign was to validate the performance of Memscon sensing systems, consisting of wireless accelerometers and strain sensors, on a real concrete structure during construction and under an actual earthquake. Another aspect of interest was to assess the effectiveness of the full damage recognition procedure based on the data recorded by the sensors and the reliability of the Decision Support System (DSS) developed in order to provide the stakeholders recommendations for building rehabilitation and the costs of this. With these ends, a Eurocode 8 spectrum-compatible accelerogram with increasing amplitude was applied at the top of an instrumented concrete frame built in the laboratory. MEMSCON sensors were directly compared with wired instruments, based on devices available on the market and taken as references, during both construction and seismic simulation.
Damage Assessment of Structures X, Pts 1 and 2, 2013
ABSTRACT This paper illustrates an application of Bayesian logic to monitoring data analysis and ... more ABSTRACT This paper illustrates an application of Bayesian logic to monitoring data analysis and structural condition state inference. The case study is a 260 m long cable-stayed bridge spanning the Adige River 10 km north of the town of Trento, Italy. This is a statically indeterminate structure, having a composite steel-concrete deck, supported by 12 stay cables. Structural redundancy, possible relaxation losses and an as-built condition differing from design, suggest that long-term load redistribution between cables can be expected. To monitor load redistribution, the owner decided to install a monitoring system which combines built-on-site elasto-magnetic and fiber-optic sensors. In this note, we discuss a rational way to improve the accuracy of the load estimate from the EM sensors taking advantage of the FOS information. More specifically, we use a multi-sensor Bayesian data fusion approach which combines the information from the two sensing systems with the prior knowledge, including design information and the outcomes of laboratory calibration. Using the data acquired to date, we demonstrate that combining the two measurements allows a more accurate estimate of the cable load, to better than 50 kN
ABSTRACT A wireless sensor network is proposed for monitoring buildings to assess earthquake dama... more ABSTRACT A wireless sensor network is proposed for monitoring buildings to assess earthquake damage. The sensor nodes use custom-developed capacitive microelectromechanical systems strain and 3-D acceleration sensors and a low power readout application-specified integrated circuit for a battery life of up to 12 years. The strain sensors are mounted at the base of the building to measure the settlement and plastic hinge activation of the building after an earthquake. They measure periodically or on-demand from the base station. The accelerometers are mounted at every floor of the building to measure the seismic response of the building during an earthquake. They record during an earthquake event using a combination of the local acceleration data and remote triggering from the base station based on the acceleration data from multiple sensors across the building. A low power network architecture was implemented over an 802.15.4 MAC in the 900-MHz band. A custom patch antenna was designed in this frequency band to obtain robust links in real-world conditions. The modules have been validated in a full-scale laboratory setup with simulated earthquakes.
The evaluation of seismic damage is today almost exclusively based on visual inspection, as build... more The evaluation of seismic damage is today almost exclusively based on visual inspection, as building owners are generally reluctant to install permanent sensing systems, due to their high installation, management and maintenance costs. To overcome this limitation, the EU-funded MEMSCON project aims to produce small size sensing nodes for measurement of strain and acceleration, integrating Micro-Electro-Mechanical Systems (MEMS) based sensors and Radio Frequency Identification (RFID) tags in a single package that will be attached to reinforced concrete buildings. To reduce the impact of installation and management, data will be transmitted to a remote base station using a wireless interface. During the project, sensor prototypes were produced by assembling pre-existing components and by developing ex-novo miniature devices with ultra-low power consumption and sensing performance beyond that offered by sensors available on the market. The paper outlines the device operating principles, production scheme and working at both unit and network levels. It also reports on validation campaigns conducted in the laboratory to assess system performance. Accelerometer sensors were tested on a reduced scale metal frame mounted on a shaking table, back to back with reference devices, while strain sensors were embedded in both reduced and full-scale reinforced concrete specimens undergoing increasing deformation cycles up to extensive damage and collapse. The paper assesses the economical sustainability and performance of the sensors developed for the project and discusses their applicability to long-term seismic monitoring.
... Daniele Zonta, Matteo Pozzi and Antonella Colombo, Department of Mechanical and Structural En... more ... Daniele Zonta, Matteo Pozzi and Antonella Colombo, Department of Mechanical and Structural Engineering, University of Trento, via Mesiano 77, 38050 Trento, Italy. Daniele Inaudi and Angelo Figini, Smartec SA, via Pobiette 11, CH-6928 Manno, Switzerland. 471 Page 494. ...
The evaluation of seismic damage is today almost exclusively based on visual inspection, as build... more The evaluation of seismic damage is today almost exclusively based on visual inspection, as building owners are generally reluctant to install permanent sensing systems, due to their high installation, management and maintenance costs. To overcome this limitation, the EU-funded MEMSCON project aims to produce small size sensing nodes for measurement of strain and acceleration, integrating Micro-Electro-Mechanical Systems (MEMS) based sensors and Radio Frequency Identification (RFID) tags in a single package that will be attached to reinforced concrete buildings and will transmit data using a wireless interface. During the first phase of the project completed so far, sensor prototypes were produced by assembling preexisting components. This paper outlines the device operating principles, production scheme and operation at both unit and network levels. It also reports on validation campaigns conducted in the laboratory to assess system performance. Accelerometer sensors were tested on a reduced scale metal frame mounted on a shaking table, while strain sensors were embedded in both reduced and full-scale reinforced concrete specimens undergoing increasing deformation cycles up to extensive damage and collapse. The performance of the sensors developed for the project and their applicability to long-term seismic monitoring are discussed.
Motivated by the preservation of an artistic treasure, the fresco of the "Cycle of the Months" on... more Motivated by the preservation of an artistic treasure, the fresco of the "Cycle of the Months" on the second floor in an historic tower, Torre Aquila, a wireless sensor network (WSN) has been developed and installed for permanent health monitoring. The monitoring scheme covers both static and dynamic evaluation of the tower structural integrity from local to global scale and consists of 17 nodes, including 2 long length fiber optic sensors (FOS), 3 accelerometers and 12 environmental nodes. The system has been working for 1.5 years and has been debugged and updated both as to hardware and software. This paper focuses mainly on the ambient vibration analysis used to investigate the performance of the sensor nodes and structural properties of the tower. Initial ambient vibration monitoring shows that cyclic environmental factors, such as traffic flow, are not the dominant cause of tower vibration; and the vibration levels of the tower in different axes are not large enough to be a critical issue calling for attention under current conditions. It proves that the WSN is an effective tool, capable of providing information relevant to safety assessment of the tower.
ABSTRACT This paper describes the application of a wireless sensor network (WSN) in Torre Aquila,... more ABSTRACT This paper describes the application of a wireless sensor network (WSN) in Torre Aquila, a 31 meter-tall medieval tower located in the city of Trento (Italy). Special attention was paid to monitoring and preservation of an artistic treasure: the fresco of the “Cycle of the Months ” on the second floor. The various sensors installed include accelerometers, thermometers and strain gauges, arranged to record both structural response and external effects (road traffic vibration, temperature change), in order to real-time calibrate the structural model parameters and to identify any possible occurrence of abnormal situations. Strain sensors include prototypes of new Fiber Optic Sensors (FOS) in view of their long-term stability and durability. Based on the first 8 months of operation in assessing the stability of the tower, the wireless system is seen to be an effective tool thanks to its customized hardware and dedicated software. The whole system is reliable and energy efficient. The comparison between the acquired measurements and simulated numerical results shows good agreement.
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