Statistics and probability analysis of vehicle overloads on a rigid frame bridge from long-term monitored strains

Liqun Tang,Yinghua Li,Zejia Liu,Yiping Liu 국제구조공학회 2012 Smart Structures and Systems, An International Jou Vol.9 No.3

It is well known that overloaded vehicles may cause severe damages to bridges, and how to estimate and evaluate the status of the overloaded vehicles passing through bridges become a challenging problem. Therefore, based on the monitored strain data from a structural health monitoring system (SHM) installed on a bridge, a method is recommended to identify and analyze the probability of overloaded vehicles. Overloaded vehicle loads can cause abnormity in the monitored strains, though the abnormal strains may be small in a concrete continuous rigid frame bridge. Firstly, the abnormal strains are identified from the abundant strains in time sequence by taking the advantage of wavelet transform in abnormal signal identification;secondly, the abnormal strains induced by heavy vehicles are picked up by the comparison between the identified abnormal strains and the strain threshold gotten by finite element analysis of the normal heavy vehicle; finally, according to the determined abnormal strains induced by overloaded vehicles, the statistics of the overloaded vehicles passing through the bridge are summarized and the whole probability of the overloaded vehicles is analyzed. The research shows the feasibility of using the monitored strains from a longterm SHM to identify the information of overloaded vehicles passing through a bridge, which can help the traffic department to master the heavy truck information and do the damage analysis of bridges further.

Influence of K2TiF6 in electrolyte on characteristics of the microarc oxidation coating on aluminum alloy

Mingqi Tang,Weiping Li,Huicong Liu,Liqun Zhu 한국물리학회 2012 Current Applied Physics Vol.12 No.5

Black and gray microarc oxidation (MAO) coatings were prepared in a phosphate electrolyte with and without K2TiF6 on 2A70 aluminum alloy, respectively. Voltageetime curves were recorded during the MAO process. The effects of K2TiF6 on the morphology, composition, abrasive resistance and corrosion resistance of MAO coatings were investigated. The results showed that the MAO coating produced in the electrolyte with K2TiF6 was thicker, and more uniform than that produced in the electrolyte without K2TiF6. Ti was detected in the surface of the MAO coating formed in the electrolyte with K2TiF6. The results of abrasive resistance and corrosion resistance showed that the MAO coating formed in the electrolyte with K2TiF6 exhibited better abrasive resistance and corrosion resistance.

Localized reliability analysis on a large-span rigid frame bridge based on monitored strains from the long-term SHM system

Zejia Liu,Liqun Tang,Yinghua Li,Yiping Liu,Zhenyu Jiang,Daining Fang 국제구조공학회 2014 Smart Structures and Systems, An International Jou Vol.14 No.2

With more and more built long-term structural health monitoring (SHM) systems, it has been considered to apply monitored data to learn the reliability of bridges. In this paper, based on a long-term SHM system, especially in which the sensors were embedded from the beginning of the construction of the bridge, a method to calculate the localized reliability around an embedded sensor is recommended and implemented. In the reliability analysis, the probability distribution of loading can be the statistics of stress transferred from the monitored strain which covered the effects of both the live and dead loads directly, and it means that the mean value and deviation of loads are fully derived from the monitored data. The probability distribution of resistance may be the statistics of strength of the material of the bridge accordingly. With five years\' monitored strains, the localized reliabilities around the monitoring sensors of a bridge were computed by the method. Further, the monitored stresses are classified into two time segments in one year period to count the loading probability distribution according to the local climate conditions, which helps us to learn the reliability in different time segments and their evolvement trends. The results show that reliabilities and their evolvement trends in different parts of the bridge are different though they are all reliable yet. The method recommended in this paper is feasible to learn the localized reliabilities revealed from monitored data of a long-term SHM system of bridges, which would help bridge engineers and managers to decide a bridge inspection or maintenance strategy

Statistics and probability analysis of vehicle overloads on a rigid frame bridge from long-term monitored strains

Li, Yinghua,Tang, Liqun,Liu, Zejia,Liu, Yiping Techno-Press 2012 Smart Structures and Systems, An International Jou Vol.9 No.3

It is well known that overloaded vehicles may cause severe damages to bridges, and how to estimate and evaluate the status of the overloaded vehicles passing through bridges become a challenging problem. Therefore, based on the monitored strain data from a structural health monitoring system (SHM) installed on a bridge, a method is recommended to identify and analyze the probability of overloaded vehicles. Overloaded vehicle loads can cause abnormity in the monitored strains, though the abnormal strains may be small in a concrete continuous rigid frame bridge. Firstly, the abnormal strains are identified from the abundant strains in time sequence by taking the advantage of wavelet transform in abnormal signal identification; secondly, the abnormal strains induced by heavy vehicles are picked up by the comparison between the identified abnormal strains and the strain threshold gotten by finite element analysis of the normal heavy vehicle; finally, according to the determined abnormal strains induced by overloaded vehicles, the statistics of the overloaded vehicles passing through the bridge are summarized and the whole probability of the overloaded vehicles is analyzed. The research shows the feasibility of using the monitored strains from a long-term SHM to identify the information of overloaded vehicles passing through a bridge, which can help the traffic department to master the heavy truck information and do the damage analysis of bridges further.

Localized reliability analysis on a large-span rigid frame bridge based on monitored strains from the long-term SHM system

Liu, Zejia,Li, Yinghua,Tang, Liqun,Liu, Yiping,Jiang, Zhenyu,Fang, Daining Techno-Press 2014 Smart Structures and Systems, An International Jou Vol.14 No.2

With more and more built long-term structural health monitoring (SHM) systems, it has been considered to apply monitored data to learn the reliability of bridges. In this paper, based on a long-term SHM system, especially in which the sensors were embedded from the beginning of the construction of the bridge, a method to calculate the localized reliability around an embedded sensor is recommended and implemented. In the reliability analysis, the probability distribution of loading can be the statistics of stress transferred from the monitored strain which covered the effects of both the live and dead loads directly, and it means that the mean value and deviation of loads are fully derived from the monitored data. The probability distribution of resistance may be the statistics of strength of the material of the bridge accordingly. With five years' monitored strains, the localized reliabilities around the monitoring sensors of a bridge were computed by the method. Further, the monitored stresses are classified into two time segments in one year period to count the loading probability distribution according to the local climate conditions, which helps us to learn the reliability in different time segments and their evolvement trends. The results show that reliabilities and their evolvement trends in different parts of the bridge are different though they are all reliable yet. The method recommended in this paper is feasible to learn the localized reliabilities revealed from monitored data of a long-term SHM system of bridges, which would help bridge engineers and managers to decide a bridge inspection or maintenance strategy.

A Novel Design of Permanent Magnet Linear Synchronous Motor with Reduced End Effect

Wu Qingle,Wang Liqun,Yang Guolai,Tang Enling,Li Lei,Al-Zahrani Ahmed 한국전자파학회 2023 Journal of Electromagnetic Engineering and Science Vol.23 No.2

In response to the end effect of the permanent magnet linear synchronous motor, this paper proposes an improved modular motor structure. To compute its electromagnetic characteristics, a subdomain model that converts the Cartesian coordinate system into a polar coordinate system through coordinate transformation is further formulated, thus significantly reducing programming difficulty. The analytical results are compared with those of the finite element method and indicate that the subdomain model can accurately consider the effects of end and flux barriers. Moreover, the magnetic field distribution inside the motor is applied to explain the end force abatement, and the suggested flux barrier width is obtained. Finally, the modular structure is applied to a 9-slot, 10-pole permanent magnet linear synchronous motor. The simulation results show that the modular structure can effectively suppress the end effect of the linear motor, and the proposed subdomain model applies to the design of the modular motor.