Pub Date : 2021-02-01DOI: 10.12989/SSS.2021.27.2.227
D. Siringoringo, J. Thiyagarajan, S. Wangchuk, Y. Fujino
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.
{"title":"Implementation of video motion magnification technique for non-contact operational modal analysis of light poles","authors":"D. Siringoringo, J. Thiyagarajan, S. Wangchuk, Y. Fujino","doi":"10.12989/SSS.2021.27.2.227","DOIUrl":"https://doi.org/10.12989/SSS.2021.27.2.227","url":null,"abstract":"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.","PeriodicalId":51155,"journal":{"name":"Smart Structures and Systems","volume":"27 1","pages":"227-239"},"PeriodicalIF":3.5,"publicationDate":"2021-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41868026","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-02-01DOI: 10.12989/SSS.2021.27.2.335
Alessandra Achilli, G. Bernagozzi, R. Betti, P. Diotallevi, L. Landi, Said Quqa, E. M. Tronci
This paper proposes a novel method suitable for vibration-based damage identification of civil structures and infrastructures under ambient excitation. The damage-sensitive feature employed in the presented algorithm consists of a vector of multivariate autoregressive parameters estimated from the vibration responses collected at different locations of the analyzed structure. Outlier analysis and statistical pattern recognition are exploited for damage detection and localization. In particular, the Mahalanobis distance between a set of reference (i.e., “healthy”) and inspection parameters is evaluated. A threshold is then selected to determine whether the inspection vectors refer to damaged or undamaged conditions. The effectiveness of the proposed approach is proved using numerical simulations and experimental data from a benchmark test. The analysis results show that the largest values of Mahalanobis distance can be found in the proximity of those sensors closest to the damaged elements. Thus, the Mahalanobis distance applied to vectors of multivariate autoregressive parameters has proven to be a robust indicator for damage detection and localization.
{"title":"On the use of multivariate autoregressive models for vibration-based damage detection and localization","authors":"Alessandra Achilli, G. Bernagozzi, R. Betti, P. Diotallevi, L. Landi, Said Quqa, E. M. Tronci","doi":"10.12989/SSS.2021.27.2.335","DOIUrl":"https://doi.org/10.12989/SSS.2021.27.2.335","url":null,"abstract":"This paper proposes a novel method suitable for vibration-based damage identification of civil structures and infrastructures under ambient excitation. The damage-sensitive feature employed in the presented algorithm consists of a vector of multivariate autoregressive parameters estimated from the vibration responses collected at different locations of the analyzed structure. Outlier analysis and statistical pattern recognition are exploited for damage detection and localization. In particular, the Mahalanobis distance between a set of reference (i.e., “healthy”) and inspection parameters is evaluated. A threshold is then selected to determine whether the inspection vectors refer to damaged or undamaged conditions. The effectiveness of the proposed approach is proved using numerical simulations and experimental data from a benchmark test. The analysis results show that the largest values of Mahalanobis distance can be found in the proximity of those sensors closest to the damaged elements. Thus, the Mahalanobis distance applied to vectors of multivariate autoregressive parameters has proven to be a robust indicator for damage detection and localization.","PeriodicalId":51155,"journal":{"name":"Smart Structures and Systems","volume":"27 1","pages":"335-350"},"PeriodicalIF":3.5,"publicationDate":"2021-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42731784","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-02-01DOI: 10.12989/SSS.2021.27.2.267
D. Su, J. Thiyagarajan, Hirofumi Tanaka, Boyu Zhao, T. Nagayama
Condition monitoring of railway tracks is essential in guaranteeing the running safety of railways. Track profiles are the primary source of external excitation for a train system. While Track Recording Vehicle is often utilized for maintenance purposes, this particular vehicle is expensive and difficult to use for small railway operators. Therefore, track profile estimation through in-service vehicle response measurements, which potentially provides efficient and frequent measurement, has been studied. However, the quantitative evaluation of the vertical and lateral track profile irregularities is still challenging as the inverse analysis solutions are sometimes inaccurate and even unstable. In this paper, numerical analyses are first carried out to evaluate track profiles from acceleration and angular velocity responses measured on a train car body. For the inverse analysis, an Augmented State Kalman Filter is utilized to solve the problem using 4 degrees of freedom observable train models. The sensor installation locations are investigated through observability rank condition analysis with different measurement layout. Secondly, a field experiment is carried out in a local Japanese in-service railway network to estimate track profile from car body motions. Smartphones are utilized for the field test measurements as prevalent sensing devices. The effectiveness of the proposed approach is demonstrated with the observable train model. Numerical analyses and field experiments clarify the proposed track profile estimation
{"title":"Response based track profile estimation using observable train models with numerical and experimental validations","authors":"D. Su, J. Thiyagarajan, Hirofumi Tanaka, Boyu Zhao, T. Nagayama","doi":"10.12989/SSS.2021.27.2.267","DOIUrl":"https://doi.org/10.12989/SSS.2021.27.2.267","url":null,"abstract":"Condition monitoring of railway tracks is essential in guaranteeing the running safety of railways. Track profiles are the primary source of external excitation for a train system. While Track Recording Vehicle is often utilized for maintenance purposes, this particular vehicle is expensive and difficult to use for small railway operators. Therefore, track profile estimation through in-service vehicle response measurements, which potentially provides efficient and frequent measurement, has been studied. However, the quantitative evaluation of the vertical and lateral track profile irregularities is still challenging as the inverse analysis solutions are sometimes inaccurate and even unstable. In this paper, numerical analyses are first carried out to evaluate track profiles from acceleration and angular velocity responses measured on a train car body. For the inverse analysis, an Augmented State Kalman Filter is utilized to solve the problem using 4 degrees of freedom observable train models. The sensor installation locations are investigated through observability rank condition analysis with different measurement layout. Secondly, a field experiment is carried out in a local Japanese in-service railway network to estimate track profile from car body motions. Smartphones are utilized for the field test measurements as prevalent sensing devices. The effectiveness of the proposed approach is demonstrated with the observable train model. Numerical analyses and field experiments clarify the proposed track profile estimation","PeriodicalId":51155,"journal":{"name":"Smart Structures and Systems","volume":"27 1","pages":"267-284"},"PeriodicalIF":3.5,"publicationDate":"2021-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41335554","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-02-01DOI: 10.12989/SSS.2021.27.2.193
Brian A. Eick, M. Smith, B. Spencer
Miter gates are water-control structures used as the damming surface on river locks and allow the water levels in the lock to raise or lower as needed. Miter gates have channel-like cross sections and are thus prone to torsional deflection due to gravity loads. To counter-act the tendency for torsional deflection and to add torsional rigidity to the gate, slender steel members termed diagonals are added across the diagonal dimension of the gate and pre-tensioned. To maintain appropriate tension in the diagonals over their lifetime, the tension in the diagonals should be monitored; however, no such monitoring is utilized. Vibration based methods to obtain an estimate of the tensile loads in the diagonal are attractive because they are simple, inexpensive, and do not require continuous monitoring. However, employing vibration-based methods to estimate the tension in the diagonals is particularly challenging because the diagonals are subjected to varying levels of submersion in water. Finding a relationship between the frequency of vibration and applied pretension that adequately addressed the effects of submersion on diagonals is difficult. This paper proposes an approach to account for the effect of submersion on the estimated tension in miter gate diagonals. Laboratory tests are conducted using scale-model diagonal specimens subjected to various levels of tension and submersion in water. The frequency of the diagonal specimens is measured and compared to an approximation using an assumed modes model. The effects of submersion on the frequency of vibration for the partially submerged diagonals are largely explained by added mass on the diagonals. Field validation is performed using a previously developed vision-based method of extracting the frequency of vibration in conjunction with the proposed method of tension estimation of an in-service miter gate diagonal that is also instrumented with load cells. Results for the proposed method show excellent agreement with load cell measurements.
{"title":"Non-contact monitoring of the tension in partially submerged, miter-gate diagonals","authors":"Brian A. Eick, M. Smith, B. Spencer","doi":"10.12989/SSS.2021.27.2.193","DOIUrl":"https://doi.org/10.12989/SSS.2021.27.2.193","url":null,"abstract":"Miter gates are water-control structures used as the damming surface on river locks and allow the water levels in the lock to raise or lower as needed. Miter gates have channel-like cross sections and are thus prone to torsional deflection due to gravity loads. To counter-act the tendency for torsional deflection and to add torsional rigidity to the gate, slender steel members termed diagonals are added across the diagonal dimension of the gate and pre-tensioned. To maintain appropriate tension in the diagonals over their lifetime, the tension in the diagonals should be monitored; however, no such monitoring is utilized. Vibration based methods to obtain an estimate of the tensile loads in the diagonal are attractive because they are simple, inexpensive, and do not require continuous monitoring. However, employing vibration-based methods to estimate the tension in the diagonals is particularly challenging because the diagonals are subjected to varying levels of submersion in water. Finding a relationship between the frequency of vibration and applied pretension that adequately addressed the effects of submersion on diagonals is difficult. This paper proposes an approach to account for the effect of submersion on the estimated tension in miter gate diagonals. Laboratory tests are conducted using scale-model diagonal specimens subjected to various levels of tension and submersion in water. The frequency of the diagonal specimens is measured and compared to an approximation using an assumed modes model. The effects of submersion on the frequency of vibration for the partially submerged diagonals are largely explained by added mass on the diagonals. Field validation is performed using a previously developed vision-based method of extracting the frequency of vibration in conjunction with the proposed method of tension estimation of an in-service miter gate diagonal that is also instrumented with load cells. Results for the proposed method show excellent agreement with load cell measurements.","PeriodicalId":51155,"journal":{"name":"Smart Structures and Systems","volume":"27 1","pages":"193-207"},"PeriodicalIF":3.5,"publicationDate":"2021-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66186896","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-02-01DOI: 10.12989/SSS.2021.27.2.241
Yang Wang, Zhichao Wang
In bridge weigh-in-motion (BWIM), dynamic bridge response is measured during traffic and used to identify overloaded vehicles. Most past studies of BWIM use mechanics-based algorithms to estimate axle weights. This research instead investigates deep learning, specifically the recurrent neural network (RNN), toward BWIM. In order to acquire the large data volume to train a RNN network that uses bridge response to estimate axle weights, a finite element bridge model is built through the commercial software package LS-DYNA. To mimic everyday traffic scenarios, tens of thousands of randomized vehicle formations are simulated, with different combinations of vehicle types, spacings, speeds, axle weights, axle distances, etc. Dynamic response from each of the randomized traffic scenarios is recorded for training the RNN. In this paper we propose a 3-stage Bidirectional RNN toward BWIM. Long short-term memory (LSTM) and attention mechanism are embedded in the BRNN to further improve the network performance. Additional test data indicates that the BRNN network achieves high accuracy in estimating axle weights, in comparison with a conventional moving force identification (MFI) method.
{"title":"Bridge weigh-in-motion through bidirectional Recurrent Neural Network with long short-term memory and attention mechanism","authors":"Yang Wang, Zhichao Wang","doi":"10.12989/SSS.2021.27.2.241","DOIUrl":"https://doi.org/10.12989/SSS.2021.27.2.241","url":null,"abstract":"In bridge weigh-in-motion (BWIM), dynamic bridge response is measured during traffic and used to identify overloaded vehicles. Most past studies of BWIM use mechanics-based algorithms to estimate axle weights. This research instead investigates deep learning, specifically the recurrent neural network (RNN), toward BWIM. In order to acquire the large data volume to train a RNN network that uses bridge response to estimate axle weights, a finite element bridge model is built through the commercial software package LS-DYNA. To mimic everyday traffic scenarios, tens of thousands of randomized vehicle formations are simulated, with different combinations of vehicle types, spacings, speeds, axle weights, axle distances, etc. Dynamic response from each of the randomized traffic scenarios is recorded for training the RNN. In this paper we propose a 3-stage Bidirectional RNN toward BWIM. Long short-term memory (LSTM) and attention mechanism are embedded in the BRNN to further improve the network performance. Additional test data indicates that the BRNN network achieves high accuracy in estimating axle weights, in comparison with a conventional moving force identification (MFI) method.","PeriodicalId":51155,"journal":{"name":"Smart Structures and Systems","volume":"27 1","pages":"241-256"},"PeriodicalIF":3.5,"publicationDate":"2021-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48535283","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-02-01DOI: 10.12989/SSS.2021.27.2.305
A. Ruccolo, C. Gentile, F. Canali
One of the most remarkable structural elements characterizing the Milan Cathedral is its Main Spire, built in Candoglia marble and completed in 1769. The Main Spire, reaching the height of about 108 m and supporting the statue of the Virgin Mary, is about 40 m high and stands on the octagonal tiburio erected around the main dome. The structural arrangement of the spire includes a central column which is connected through a spiral staircase to 8 perimeter columns and each column is stiffened by inverse flying buttress. Metallic clamps and dowels connect the marble blocks and metallic rods connect the perimeter columns to the central core. A large monitoring system was recently installed in the Milan Cathedral, including seismometers and temperature sensors at 3 levels of the Main Spire as well as a weather station at the top of the spire. After a concise historic background on the Main Spire and the description of the sensing devices installed in this structure, the paper focuses on the dynamic characteristics of the spire and their evolution during a time span of about 16 months. The presented results highlight that: (a) a high density of vibration modes is automatically detected in the frequency range 1.0-7.0 Hz; (b) the lower identified modes correspond to global modes of the cathedral; (c) the normal evolution in time of the resonant frequencies is characterized by clear fluctuations induced by the environmental effects (temperature and wind); (d) especially the dependence of resonant frequencies on temperature is very distinctive and reveals the key role of the metallic elements in the overall dynamic behavior; (e) notwithstanding the remarkable effects exerted by the changing environment on the resonant frequencies, output-only removal of environmental effects and novelty analysis allow an effective monitoring of the structural condition.
{"title":"Monitoring an iconic heritage structure with OMA: the Main Spire of the Milan Cathedral","authors":"A. Ruccolo, C. Gentile, F. Canali","doi":"10.12989/SSS.2021.27.2.305","DOIUrl":"https://doi.org/10.12989/SSS.2021.27.2.305","url":null,"abstract":"One of the most remarkable structural elements characterizing the Milan Cathedral is its Main Spire, built in Candoglia marble and completed in 1769. The Main Spire, reaching the height of about 108 m and supporting the statue of the Virgin Mary, is about 40 m high and stands on the octagonal tiburio erected around the main dome. The structural arrangement of the spire includes a central column which is connected through a spiral staircase to 8 perimeter columns and each column is stiffened by inverse flying buttress. Metallic clamps and dowels connect the marble blocks and metallic rods connect the perimeter columns to the central core. A large monitoring system was recently installed in the Milan Cathedral, including seismometers and temperature sensors at 3 levels of the Main Spire as well as a weather station at the top of the spire. After a concise historic background on the Main Spire and the description of the sensing devices installed in this structure, the paper focuses on the dynamic characteristics of the spire and their evolution during a time span of about 16 months. The presented results highlight that: (a) a high density of vibration modes is automatically detected in the frequency range 1.0-7.0 Hz; (b) the lower identified modes correspond to global modes of the cathedral; (c) the normal evolution in time of the resonant frequencies is characterized by clear fluctuations induced by the environmental effects (temperature and wind); (d) especially the dependence of resonant frequencies on temperature is very distinctive and reveals the key role of the metallic elements in the overall dynamic behavior; (e) notwithstanding the remarkable effects exerted by the changing environment on the resonant frequencies, output-only removal of environmental effects and novelty analysis allow an effective monitoring of the structural condition.","PeriodicalId":51155,"journal":{"name":"Smart Structures and Systems","volume":"27 1","pages":"305-318"},"PeriodicalIF":3.5,"publicationDate":"2021-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47121156","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-02-01DOI: 10.12989/SSS.2021.27.2.257
Lijun Liu, Jianan Mi, Yixiao Zhang, Y. Lei
Since it may be hard to obtain the exact external load in practice, damage identification of bridge structures using only structural responses under unknown seismic excitations is an important but challenging task. Since structural responses are determined by both structural properties and seismic excitation, it is necessary to remove the effects of external excitation and only retain the structural information for structural damage identification. In this paper, a data-driven approach using structural responses only is proposed for structural damage alarming and localization of bridge structures. The transmissibility functions (TF) of structural responses are used to eliminate the influence of unknown seismic excitations. Moreover, the inverse Fourier transform of TFs and wavelet packet transform are used to reduce the influence of frequency bands and to extract the damagesensitive feature, respectively. Based on Support vector machines (SVM), structural responses under ambient excitations are used for training SVM. Then, structural responses under unknown seismic excitations are also processed accordingly and used for damage alarming and localization by the trained SMV. The numerical simulation examples of beam-type bridge and a cablestayed bridge under unknown seismic excitations are studied to illustrate the performance of the proposed approach.
{"title":"Damage detection of bridge structures under unknown seismic excitations using support vector machine based on transmissibility function and wavelet packet energy","authors":"Lijun Liu, Jianan Mi, Yixiao Zhang, Y. Lei","doi":"10.12989/SSS.2021.27.2.257","DOIUrl":"https://doi.org/10.12989/SSS.2021.27.2.257","url":null,"abstract":"Since it may be hard to obtain the exact external load in practice, damage identification of bridge structures using only structural responses under unknown seismic excitations is an important but challenging task. Since structural responses are determined by both structural properties and seismic excitation, it is necessary to remove the effects of external excitation and only retain the structural information for structural damage identification. In this paper, a data-driven approach using structural responses only is proposed for structural damage alarming and localization of bridge structures. The transmissibility functions (TF) of structural responses are used to eliminate the influence of unknown seismic excitations. Moreover, the inverse Fourier transform of TFs and wavelet packet transform are used to reduce the influence of frequency bands and to extract the damagesensitive feature, respectively. Based on Support vector machines (SVM), structural responses under ambient excitations are used for training SVM. Then, structural responses under unknown seismic excitations are also processed accordingly and used for damage alarming and localization by the trained SMV. The numerical simulation examples of beam-type bridge and a cablestayed bridge under unknown seismic excitations are studied to illustrate the performance of the proposed approach.","PeriodicalId":51155,"journal":{"name":"Smart Structures and Systems","volume":"27 1","pages":"257-266"},"PeriodicalIF":3.5,"publicationDate":"2021-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46031987","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-02-01DOI: 10.12989/SSS.2021.27.2.397
F. Castillo-García, Sergio Juárez-Pérez, A. González-Rodríguez, Guillermo Rubio-Gómez, David Rodríguez-Rosa, E. Ottaviano
Inspection and maintenance of civil structures are important issues for sustainability of existing and new infrastructures. Classical approach relies on large human activities eventually performed in unsafe conditions. This paper proposed a non-invasive solution for inspecting horizontal surface such as decks of bridges. The proposal presented here is based in cable-driven robots and allows to inspect large surfaces maintaining a very low vertical occupancy in comparison to the conventional architecture of this kind of robot. Using closed cables loop instead of a set of cables a device with low motorization power and very large workspace is designed and prototyped. As example of control an inverse dynamics technique is applied to control the end-effector where inspection tool is located, e.g., a vision system. Experimental results demonstrate that this novel device allows to inspect large horizontal surfaces, with low motorization and low vertical occupancy.
{"title":"Closed loop cable robot for large horizontal workspaces","authors":"F. Castillo-García, Sergio Juárez-Pérez, A. González-Rodríguez, Guillermo Rubio-Gómez, David Rodríguez-Rosa, E. Ottaviano","doi":"10.12989/SSS.2021.27.2.397","DOIUrl":"https://doi.org/10.12989/SSS.2021.27.2.397","url":null,"abstract":"Inspection and maintenance of civil structures are important issues for sustainability of existing and new infrastructures. Classical approach relies on large human activities eventually performed in unsafe conditions. This paper proposed a non-invasive solution for inspecting horizontal surface such as decks of bridges. The proposal presented here is based in cable-driven robots and allows to inspect large surfaces maintaining a very low vertical occupancy in comparison to the conventional architecture of this kind of robot. Using closed cables loop instead of a set of cables a device with low motorization power and very large workspace is designed and prototyped. As example of control an inverse dynamics technique is applied to control the end-effector where inspection tool is located, e.g., a vision system. Experimental results demonstrate that this novel device allows to inspect large horizontal surfaces, with low motorization and low vertical occupancy.","PeriodicalId":51155,"journal":{"name":"Smart Structures and Systems","volume":"27 1","pages":"397-406"},"PeriodicalIF":3.5,"publicationDate":"2021-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43492585","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-01-01DOI: 10.12989/SSS.2021.28.3.333
Jinwoo Park, Yeol-Hun Sung, S. On, O. Kwon, H. Bang, S. Kim, Jae-Hung Han, Jung‐Ryul Lee
{"title":"Development of wireless SHM sensor node for in-flight real-time monitoring using embedded CNT fiber sensors","authors":"Jinwoo Park, Yeol-Hun Sung, S. On, O. Kwon, H. Bang, S. Kim, Jae-Hung Han, Jung‐Ryul Lee","doi":"10.12989/SSS.2021.28.3.333","DOIUrl":"https://doi.org/10.12989/SSS.2021.28.3.333","url":null,"abstract":"","PeriodicalId":51155,"journal":{"name":"Smart Structures and Systems","volume":"28 1","pages":"333-341"},"PeriodicalIF":3.5,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66187603","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-01-01DOI: 10.12989/SSS.2021.27.1.001
M. Mehrabi, M. Mohammadimehr, F. Mousavinejad
In the present study, the free vibration analysis of a size-dependent micro composite Timoshenko beam model reinforced by various distributions of carbon nanotubes under temperature changes and two-dimensional magnetic field is investigated based on modified strain gradient theory. Also, the effects of environment are simulated by orthotropic elastic foundation and it is assumed that the material properties are temperature-dependent. Mathematical formulations are obtained using Hamilton's principle and the governing equations of motion are derived based on energy approach and variation method. These equations are solved using semi-analytical and numerical methods such as Navier's type solution, finite element method and generalized differential quadrature method for various boundary conditions. The obtained results of this study are compared with the other previous researches and there is a good agreement between them. The main purpose of this work is the comparison of various solution methods on the problem outputs. Thus, the results are compared together and the effects of solution approach on the dimensionless natural frequencies is developed. Moreover, the effects of length-to-thickness ratio, magnetic field, temperature changes, elastic foundation and carbon nanotubes volume fractions on the dimensionless natural frequencies are studied. The results of this article demonstrate that the micro composite Timoshenko beam reinforced by FG-O and FG-X CNTs have lowest and highest dimensionless natural frequency, respectively. It is investigated that the dimensionless natural frequency enhances by increasing the magnetic field in x and z-directions.
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