An Adaptive Filtering Method for Bridge Vibration Signals Based on Improved CEEMDAN and Multi-Scale Permutation Entropy

Aiming at the serious noise of bridge vibration signals in complex environment, this paper proposed an adaptive filtering and denoising optimization method for bridge structural health monitoring. The method took CEEMDAN algorithm as the core, during the step-by-step decomposition of original signals, white noise with opposite signs was added in each stage, meanwhile multi-scale permutation entropy (MPE) was introduced to analyze the mean entropy of each intrinsic mode function (IMF) at different scales, and components with serious noise were eliminated to complete the first filtering; then, in order to optimize the remaining IMFs for signal reconstruction and ensuring the smoothness and similarity of filtering, an optimized reconstruction model was established to complete the second filtering. Compared with the CEEMDAN method, the proposed method could solve the problems of mode mixing and endpoint effect with good completeness, orthogonality, and signal-to-noise ratio. At last, the advantages and application value of the proposed method were verified again by the vibration signal analysis of a real long-span bridge structure.

Value-Engineering Methodology for the Selection of an Optimal Bridge System

Maintaining and enhancing the functionality of the infrastructure at an affordable cost are major challenges for decision makers, particularly given the need to cope with growing societal and transportation demands. This study introduces a systematic multi-criteria value engineering (VE) approach for the selection of a sustainable bridge system. A thorough VE analysis for a proposed long-span bridge in New Jersey, USA was carried out as a pilot study. The function analysis system technique was used to develop logical relationships between the project’s functions. A detailed 100-year life-cycle cost analysis (LCCA) was conducted. The study developed and evaluated eight alternative designs for deck and superstructure systems against set VE criteria comprising constructability, maintenance strategies, and environmental impact. A relative value index was used as an unbiased measure for the selection of the optimal structural system. With total savings of approximately 21% of the original design ($132.5 million), steel plate girders with a high-performance lightweight steel grid deck system have proven to “outvalue” the other alternatives, including the preferred preliminary alternative (PPA). Design engineers and decision makers can use this methodology as a systematic and convenient guide for the selection of economical and sustainable bridge systems. As such, it is necessary to re-evaluate the current practices and policies used for this purpose.

Analysis of the dynamic response of long span bridges with GNSS under typhoon loading

Nowadays, real-time bridge deformation monitoring has attracted more attention due to the development of bridge management system and land transportation safety. Huge civil engineering structures, such as long-span bridge, is susceptible to dynamic deflection caused by various loadings. Hence, precise dynamic response measurement becomes necessary to make structure more reliable and integrated. Currently, Global Navigation Satellite System (GNSS) positioning technology has been commonly used in this field to detect the dynamic displacement of long-span bridges. According to this, real-time data were collected from the Forth Road Bridge to observe the dynamic response of lang span bridges under extreme wind load conditions and this report has also verified the data processing technique of the real-time bridge deformation monitoring system. Compared with other monitoring methods, the method used in this report which combines GNSS and anemometer together has features of high frequency with low lag. Moreover, it also shows the superiority of post-processing and synchronization, background noises could be reduced by embedded software. Finally, according to the cross-correlation analysis, it was found that wind speed and bridge displacement in y-axis have the highest correlation. Also, the reliability of combining method to monitor the dynamic response of long-span bridge and noise reducing method proposed in this report has also been verified.

Tracking of Stiffness Variation in Structural Members Using Input Error Function Observers

This study evaluates input error function observers for tracking of stiffness variation in real-time. The input error function is an Analytical Redundancy (AR)-based diagnosis method and necessitates a mathematical model of the system and system identification techniques. In practice, mathematical models used during numerical simulations differ from the actual status of the structure, and thus, accurate mathematical models are rarely available for reference. Noise is an unwanted signal in the input–output measurements but unavoidable in real-world applications (as in long span bridge trusses) and hard to imitate during numerical simulations. Simulation data from the truss system clearly indicates the effectiveness of the proposed structural damage detection method for estimating the severity of the damage. Optimization of the input error function can further automate the stiffness estimation in structural members and address critical aspects such as system uncertainties and the presence of noise in input–output measurements. Stiffness tracking in one of the planar truss members indicates the potential of optimization of the input error function for online structural health monitoring and implementing condition-based maintenance.

Suppression of Bridge Flutter Using Suction Control

To verify the effectiveness of the suction-based method for improving flutter stability of long-span bridges, the forced vibration experiments for extracting the flutter derivatives of a section model with and without suction were performed, and the corresponding critical flutter wind speeds of this structure were calculated out. It is shown by the experiment that the flutter stability of the bridge depends on suction configuration. As the suction holes locate at the leeward side of the model, the critical flutter wind speed can attain maximum under the same suction velocity. In the analytical results, it is remarkably effective that the suction control improves the long-span bridge flutter stability.

Review on the Impact of Elements Used During Bridge Construction

The requirement of long span bridge is increase with development of infrastructure facility in every nation. Long span bridge could be achieved with use of high strength materials and innovative techniques for analysis of bridge. Generally, cable-supported bridges comprise both suspension and cable-stayed bridges. Cable-supported bridges are very flexible in behavior. These flexible systems are susceptible to the dynamic effects of wind and earthquake loads. The cable-stayed bridge could provide more rigidity due to the presence of tensed cable stays as a force resistance element.