Much of the research has focused on identifying bridge frequencies for health monitoring,while the bridge damping ratio also serves as an important factor in damage detection.This study presents an enhanced method for...Much of the research has focused on identifying bridge frequencies for health monitoring,while the bridge damping ratio also serves as an important factor in damage detection.This study presents an enhanced method for identifying bridge damping ratios using a two-axle,three-mass test vehicle,relying on wheel responses captured by only two mounted sensors.Damping ratio estimation formulas are derived using both the Hilbert Transform(HT)and Wavelet Transform(WT),with a consistent formulation that confirms accurate estimation is achievable with minimal instrumentation,particularly when addressing the support effect.A comparative analysis of the two signal processing techniques reveals the superior performance of WT in identifying bridge damping ratios.The effectiveness of the proposed procedure and formulas is validated through a detailed parametric study,demonstrating robustness across bridges with varying modal damping ratios and different spans using minimal sensors.Moreover,the present study shows that responses from only the first two spans of a multi-span bridge are sufficient for reliable damping estimation,underscoring the practicality and scalability of the procedure for structural health monitoring applications.展开更多
The high profile failure of the Malahide Viaduct in Dublin, Ireland, which is a part of the EU TEN-T network of critical transport links, was caused by foundation scour. Scour is a common soil-structure interaction pr...The high profile failure of the Malahide Viaduct in Dublin, Ireland, which is a part of the EU TEN-T network of critical transport links, was caused by foundation scour. Scour is a common soil-structure interaction problem. In light of current changes in climate, increasing frequency of flooding, coupled with the increasing magnitude of these flood events, will lead to a higher risk of bridge failure. Moni- toring scour is of paramount importance to ensure the continued safe operation of the aging bridge asset network. Most monitoring regimes are based on expensive underwater instrumentation that can often be subjected to damage during times of flooding, when scour risk is at its highest. This paper presents a critical review of existing scour monitoring equipments and methodologies with a particular focus on those using the dynamic response of the structure to indicate the existence and severity of the scour phenomenon affecting the structure. A sensitivity study on a recently developed monitoring method is also undertaken.展开更多
Aiming at the all-weather automatic monitoring of bridge structure health monitoring,an embedded bridge multi-dimensional(horizontal and vertical)deflection monitoring system based on dual laser references is proposed...Aiming at the all-weather automatic monitoring of bridge structure health monitoring,an embedded bridge multi-dimensional(horizontal and vertical)deflection monitoring system based on dual laser references is proposed.The controller turns on the laser reference transmitter through instructions to emit the laser reference.The intelligent target system located in the middle of the span will calculate the multi-dimensional deflection and deformation information of the bridge structure according to the laser spot projected on the diffuse optical target,and pass this information through the wireless network communication unit transmits to the cloud platform to realize real-time monitoring of the bridge structure status and other parameters.Through the laboratory platform,it is found that the measurement error of this method is less than 300μm,and the data update rate is less than 66 ms,which meets the requirements of bridge structural health monitoring.This method solves the problem of low efficiency of artificial bridge deflection monitoring,realizes all-weather online real-time monitoring of bridge deflection detection,and ensures the accuracy and efficiency of the measurement system.Applying this monitoring technology not only significantly improves the efficiency and accuracy of bridge structural health monitoring but also plays a crucial role in ensuring safe bridge operations,extending the service life of bridges,and reducing maintenance costs.展开更多
The self-assembly reactions of Co(NCS) 2 with diester-bridged pyridine-based ligands pyCO 2-(CH 2) m-O 2Cpy (py=4-pyridyl; m=2, 3, 4) have been studied. Interestingly, while Co^(NCS) 2 reacted with pyCO 2-(CH ...The self-assembly reactions of Co(NCS) 2 with diester-bridged pyridine-based ligands pyCO 2-(CH 2) m-O 2Cpy (py=4-pyridyl; m=2, 3, 4) have been studied. Interestingly, while Co^(NCS) 2 reacted with pyCO 2-(CH 2) 2-O 2Cpy (La) in MeOH/H 2O or THF/MeCN to yield two coordination polymers [Co^(NCS) 2(La) 2] n(1) and [Co(NCS) 2(La) 2·2THF] n(2), reactions of Co(NCS) 2 with pyCO 2-(CH 2) 3-O 2Cpy (Lb) in MeOH/MeCN and Co(NCS) 2 with pyCO 2-(CH 2) 4-O 2Cpy (Lc) in EtOH/H 2O afforded [Co(NCS) 2(Lb) 2· 0.5MeOH] n(3) and [Co(NCS) 2(Lc) 2·2H 2O] n(4), respectively. The X-ray diffraction analyses indicated that polymers 1-4 consist of a one-dimensional Co(II) chain in which each of the two adjacent Co(II) ions is bridged by two pyCO 2-(CH 2) m-O 2Cpy ligands to form a macrocycle. In addition, the structures of polymers 1-4 were also characterized by infrared spectroscopy, thermogravimetry and elemental analysis.展开更多
文摘Much of the research has focused on identifying bridge frequencies for health monitoring,while the bridge damping ratio also serves as an important factor in damage detection.This study presents an enhanced method for identifying bridge damping ratios using a two-axle,three-mass test vehicle,relying on wheel responses captured by only two mounted sensors.Damping ratio estimation formulas are derived using both the Hilbert Transform(HT)and Wavelet Transform(WT),with a consistent formulation that confirms accurate estimation is achievable with minimal instrumentation,particularly when addressing the support effect.A comparative analysis of the two signal processing techniques reveals the superior performance of WT in identifying bridge damping ratios.The effectiveness of the proposed procedure and formulas is validated through a detailed parametric study,demonstrating robustness across bridges with varying modal damping ratios and different spans using minimal sensors.Moreover,the present study shows that responses from only the first two spans of a multi-span bridge are sufficient for reliable damping estimation,underscoring the practicality and scalability of the procedure for structural health monitoring applications.
基金the support of the Earth and Natural Sciences(ENS) Doctoral Studies Programfunded by the Higher Education Authority(HEA) through the Program for Research at Third Level Institutions,Cycle 5(PRTLI-5)+1 种基金co-funded by the European Regional Development Fund(ERDF)the European Union Framework 7 project SMART RAIL(Project No.285683)
文摘The high profile failure of the Malahide Viaduct in Dublin, Ireland, which is a part of the EU TEN-T network of critical transport links, was caused by foundation scour. Scour is a common soil-structure interaction problem. In light of current changes in climate, increasing frequency of flooding, coupled with the increasing magnitude of these flood events, will lead to a higher risk of bridge failure. Moni- toring scour is of paramount importance to ensure the continued safe operation of the aging bridge asset network. Most monitoring regimes are based on expensive underwater instrumentation that can often be subjected to damage during times of flooding, when scour risk is at its highest. This paper presents a critical review of existing scour monitoring equipments and methodologies with a particular focus on those using the dynamic response of the structure to indicate the existence and severity of the scour phenomenon affecting the structure. A sensitivity study on a recently developed monitoring method is also undertaken.
基金supported by National Natural Science Foundation of China(NSFC)(No.52172324)Shaanxi Provincial Key Research and Development Program(No.2021GY-285 and 2021SF-483)+1 种基金The Science and Technology Project of Shaanxi Provincial Transportation Department(No.21-20K)open fund project of the Xi'an Key Laboratory of Intelligent Expressway Information Fusion and Control(Chang'an University)(300102321502)。
文摘Aiming at the all-weather automatic monitoring of bridge structure health monitoring,an embedded bridge multi-dimensional(horizontal and vertical)deflection monitoring system based on dual laser references is proposed.The controller turns on the laser reference transmitter through instructions to emit the laser reference.The intelligent target system located in the middle of the span will calculate the multi-dimensional deflection and deformation information of the bridge structure according to the laser spot projected on the diffuse optical target,and pass this information through the wireless network communication unit transmits to the cloud platform to realize real-time monitoring of the bridge structure status and other parameters.Through the laboratory platform,it is found that the measurement error of this method is less than 300μm,and the data update rate is less than 66 ms,which meets the requirements of bridge structural health monitoring.This method solves the problem of low efficiency of artificial bridge deflection monitoring,realizes all-weather online real-time monitoring of bridge deflection detection,and ensures the accuracy and efficiency of the measurement system.Applying this monitoring technology not only significantly improves the efficiency and accuracy of bridge structural health monitoring but also plays a crucial role in ensuring safe bridge operations,extending the service life of bridges,and reducing maintenance costs.
文摘The self-assembly reactions of Co(NCS) 2 with diester-bridged pyridine-based ligands pyCO 2-(CH 2) m-O 2Cpy (py=4-pyridyl; m=2, 3, 4) have been studied. Interestingly, while Co^(NCS) 2 reacted with pyCO 2-(CH 2) 2-O 2Cpy (La) in MeOH/H 2O or THF/MeCN to yield two coordination polymers [Co^(NCS) 2(La) 2] n(1) and [Co(NCS) 2(La) 2·2THF] n(2), reactions of Co(NCS) 2 with pyCO 2-(CH 2) 3-O 2Cpy (Lb) in MeOH/MeCN and Co(NCS) 2 with pyCO 2-(CH 2) 4-O 2Cpy (Lc) in EtOH/H 2O afforded [Co(NCS) 2(Lb) 2· 0.5MeOH] n(3) and [Co(NCS) 2(Lc) 2·2H 2O] n(4), respectively. The X-ray diffraction analyses indicated that polymers 1-4 consist of a one-dimensional Co(II) chain in which each of the two adjacent Co(II) ions is bridged by two pyCO 2-(CH 2) m-O 2Cpy ligands to form a macrocycle. In addition, the structures of polymers 1-4 were also characterized by infrared spectroscopy, thermogravimetry and elemental analysis.
