The application of a fuzzy inference system and analytical hierarchy process based online evaluation framework to the Donghai Bridge Health Monitoring System

Dan, Danhui,Sun, Limin,Yang, Zhifang,Xie, Daqi Techno-Press 2014 Smart Structures and Systems, An International Jou Vol.14 No.2

In this paper, a fuzzy inference system and an analytical hierarchy process-based online evaluation technique is developed to monitor the condition of the 32-km Donghai Bridge in Shanghai. The system has 478 sensors distributed along eight segments selected from the whole bridge. An online evaluation subsystem is realized, which uses raw data and extracted features or indices to give a set of hierarchically organized condition evaluations. The thresholds of each index were set to an initial value obtained from a structure damage and performance evolution analysis of the bridge. After one year of baseline monitoring, the initial threshold system was updated from the collected data. The results show that the techniques described are valid and reliable. The online method fulfills long-term infrastructure health monitoring requirements for the Donghai Bridge.

Determination of cable force based on the corrected numerical solution of cable vibration frequency equations

Dan, Danhui,Chen, Yanyang,Yan, Xingfei Techno-Press 2014 Structural Engineering and Mechanics, An Int'l Jou Vol.50 No.1

The accurate determination of cable tension is important to the monitoring of the condition of a cable-stayed bridge. When applying a vibration-based formula to identify the tension of a real cable under sag, stiffness and boundary conditions, the resulting error must not be overlooked. In this work, by resolving the implicit frequency function of a real cable under the above conditions numerically, indirect methods of determining the cable force and a method to calculate the corresponding cable mode frequency are investigated. The error in the tension is studied by numerical simulation, and an empirical error correction formula is presented by fitting the relationship between the cable force error and cable parameters ${\lambda}^2$ and ${\xi}$. A case study on two real cables of the Shanghai Changjiang Bridge shows that employing the method proposed in this paper can increase the accuracy of the determined cable force and reduce the computing time relative to the time required for the finite element model.

Determination of cable force based on the corrected numerical solution of cable vibration frequency equations

Danhui Dan,Yanyang Chen,Xingfei Yan 국제구조공학회 2014 Structural Engineering and Mechanics, An Int'l Jou Vol.50 No.1

The accurate determination of cable tension is important to the monitoring of the condition of a cable-stayed bridge. When applying a vibration-based formula to identify the tension of a real cable under sag, stiffness and boundary conditions, the resulting error must not be overlooked. In this work, by resolvingthe implicit frequency function of a real cable under the above conditions numerically, indirect methods of determining the cable force and a method to calculate the corresponding cable mode frequency are investigated. The error in the tension is studied by numerical simulation, and an empirical error correction formula is presented by fitting the relationship between the cable force error and cable parameters λ2 and ξ. A case study on two real cables of the Shanghai Changjiang Bridge shows that employing the method proposed in this paper can increase the accuracy of the determined cable force and reduce the computing time relative to the time required for the finite element model.

The application of a fuzzy inference system and analytical hierarchy process based online evaluation framework to the Donghai Bridge Health Monitoring System

Danhui Dan,Limin Sun,Zhifang Yang,Daqi Xie 국제구조공학회 2014 Smart Structures and Systems, An International Jou Vol.14 No.2

In this paper, a fuzzy inference system and an analytical hierarchy process-based online evaluation technique is developed to monitor the condition of the 32-km Donghai Bridge in Shanghai. The system has 478 sensors distributed along eight segments selected from the whole bridge. An online evaluation subsystem is realized, which uses raw data and extracted features or indices to give a set of hierarchically organized condition evaluations. The thresholds of each index were set to an initial value obtained from a structure damage and performance evolution analysis of the bridge. After one year of baseline monitoring, the initial threshold system was updated from the collected data. The results show that the techniques described are valid and reliable. The online method fulfills long-term infrastructure health monitoring requirements for the Donghai Bridge.

Cloud monitoring system for assembled beam bridge based on index of dynamic strain correlation coefficient

Yiming Zhao,Danhui Dan,Xingfei Yan,Kailong Zhang 국제구조공학회 2020 Smart Structures and Systems, An International Jou Vol.26 No.1

The hinge joint is the key to the overall cooperative working performance of the assembled beam bridge, and it is also the weakest part during the service period. This paper proposes a method for monitoring and evaluating the lateral cooperative working performance of fabricated beam bridges based on dynamic strain correlation coefficient indicator. This method is suitable for monitoring and evaluation of hinge joints status between prefabricated girders and overall cooperative working performance of bridge, without interruption of traffic and easy implementation. The remote cloud monitoring and diagnosis system was designed and implemented on a real assembled beam bridge. The algorithms of data preprocessing, online indicator extraction and status diagnosis were given, and the corresponding software platform and scientific computing environment for cloud operation were developed. Through the analysis of real bridge monitoring data, the effectiveness and accuracy of the method are proved and it can be used in the health monitoring system of such bridges.

Research on Vehicle-Induced Vibration of Pedestrian Bridge and Its Application in Comfort Evaluation

Zhao Rui,Wu Yuhang,Dan Danhui 한국강구조학회 2024 International Journal of Steel Structures Vol.24 No.1

The vibration responses of pedestrian bridges are mainly caused by two transmission routes of ground and airfl ow under vehicle excitation. In order to clarify the action mechanism and infl uence degree of ground excitation and airfl ow excitation on pedestrian bridges, based on stochastic theory and fl ow fi eld analysis method, the calculation models of vehicle-induced ground excitation and airfl ow excitation considering the infl uence of vehicle length, vehicle width and bridge deck width are established respectively. Considering the eff ects of vehicle speed, road grade, and vehicle mass, the vibration response of a continuous steel box girder pedestrian bridge under the two transmission routes was analyzed in this study. The laws of vibration acceleration and stress were summarized, and the accuracy of the fi nite element model and the laws were verifi ed by fi eld-measured data. Results show that road grade and vehicle mass are the main factors causing the vibrations of pedestrian bridges under vehicle excitation. Vehicle speed has a great infl uence on structural vibration under airfl ow excitation. The vibration response is the largest at mid-span along the pedestrian bridge-length direction. When the vehicle speed is less than about 60 km/h, the infl uence of the airfl ow excitation on the structure may not be considered. On this basis, the comfort level of the pedestrian bridge was evaluated using the British Standards Institution. The given evaluation criteria of the pedestrian bridge complement the design regulations of the pedestrian bridge.

MULTIPLICATION OPERATORS ON BERGMAN SPACES OVER POLYDISKS ASSOCIATED WITH INTEGER MATRIX

Dan, Hui,Huang, Hansong Korean Mathematical Society 2018 대한수학회보 Vol.55 No.1

This paper mainly considers a tuple of multiplication operators on Bergman spaces over polydisks which essentially arise from a matrix, their joint reducing subspaces and associated von Neumann algebras. It is shown that there is an interesting link of the non-triviality for such von Neumann algebras with the determinant of the matrix. A complete characterization of their abelian property is given under a more general setting.