The deformation monitoring of long-span railway bridges is significant to ensure the safety of human life and property.The interferometric synthetic aperture radar(In SAR)technology has the advantage of high accuracy ...The deformation monitoring of long-span railway bridges is significant to ensure the safety of human life and property.The interferometric synthetic aperture radar(In SAR)technology has the advantage of high accuracy in bridge deformation monitoring.This study monitored the deformation of the Ganjiang Super Bridge based on the small baseline subsets(SBAS)In SAR technology and Sentinel-1A data.We analyzed the deformation results combined with bridge structure,temperature,and riverbed sediment scouring.The results are as follows:(1)The Ganjiang Super Bridge area is stable overall,with deformation rates ranging from-15.6 mm/yr to 10.7 mm/yr(2)The settlement of the Ganjiang Super Bridge deck gradually increases from the bridge tower toward the main span,which conforms to the typical deformation pattern of a cable-stayed bridge.(3)The sediment scouring from the riverbed cause the serious settlement on the bridge’s east side compared with that on the west side.(4)The bridge deformation negatively correlates with temperature,with a faster settlement at a higher temperature and a slow rebound trend at a lower temperature.The study findings can provide scientific data support for the health monitoring of long-span railway bridges.展开更多
In the city of Gdansk in Poland,in the very center of the Baltic capital,on 17th of June 2017,a new draw footbridge was ceremoniously opened to the public.The Olowianka footbridge represents the long-time much needed ...In the city of Gdansk in Poland,in the very center of the Baltic capital,on 17th of June 2017,a new draw footbridge was ceremoniously opened to the public.The Olowianka footbridge represents the long-time much needed link between the highly tourist-visited historical old town and Ołowianka Island,where further cultural,tourist and recreation facilities are located.The bridge spans a very busy navigable channel of the Motława River,leading inward towards other city channels,a harbor for many tourist ships and the Gdansk Marina.Being the main navigable entrance to the city center,the Motława is constantly under nautical traffic,so the Ołowianka footbridge operates 24/7,according to a 30-min schedule.The Ołowianka footbridge is an extraordinary acquisition for the city of Gdansk,which immediately became a new landmark and much more in the already very picturesque historic city center.Not just its design,but also its carefully chosen location and its realization at the right moment,has made this bridge indispensable to the inhabitants,visitors and the administration of the city of Gdansk,decisively contributing to further development in the Ołowianka Island area and its surroundings.展开更多
Research on the lateral vibrational stability of footbridges has attracted increasing attention in recent years. However, this stability contains a series of complex mechanisms, such as nonlinear vibration, random exc...Research on the lateral vibrational stability of footbridges has attracted increasing attention in recent years. However, this stability contains a series of complex mechanisms, such as nonlinear vibration, random excitation, andrandom stability. The Lyapunov method is regarded as an effective tool for analyzing random vibrational stability;however, it is a qualitative method and can only provide a binary judgment for stability. This study proposes anew method, IEVIE–SA, which combines the energy method based on the comparison between the input energyand the variation of intrinsic energy (IEVIE) and the stochastic averaging (SA) method. The improved Nakamuramodel was used to describe the lateral nonlinear stochastic vibration of a footbridge, whereby the IEVIE methodwas used to establish the criteria for judging the lateral vibrational stability. Additionally, the SA method was usedto deduce the corresponding backward Kolmogorov equation. Subsequently, the backward Kolmogorov equationwas combined with the stability criterion established by the IEVIE method to analyze the first passage stability. Theproposed method is a semi-analytical, quantitative method that only requires a small calculation. By applying theproposed method to the Millennium Bridge, method effectiveness was verified by comparing it with the MonteCarlo and traditional Lyapunov methods.展开更多
Combining GPS and BDS technology to monitor the deformation of long-span railway bridges with stricter deformation control requirements is of significance to the safety and control of the bridge and the safety of rail...Combining GPS and BDS technology to monitor the deformation of long-span railway bridges with stricter deformation control requirements is of significance to the safety and control of the bridge and the safety of railway traffic.Previous studies have ignored the influence of coloured noise in the deformation time series.This is not conducive to accurate deformation analysis of long-span railway bridges.Therefore,GPS,BDS and GPS/BDS monitoring data of Ganjiang Bridge located in Ganzhou city,Jiangxi Province,China are adopted in this paper to filter the coloured noise in the deformation time series by principal component analysis(PCA),and the influence of coloured noise on the deformation analysis results of railway bridge is analysed.The experimental results show that the diurnal temperature difference causes the mid-span and the tower of the railway cable-stayed bridge to deform with a period of about one day in the vertical and longitudinal directions,respectively.Ignoring colored noise will make the uncertainty of the deformation parameter estimation overly optimistic.PCA can significantly reduce the coloured noise,and thus reduce the uncertainty of deformation parameter estimation by about 73%.Moreover,the average difference between the daily periodic motion amplitudes of the monitoring points obtained by using GPS and BDS deformation time series is 1.65 mm.The use of GPS/BDS deformation time series is not only helpful to reduce the influence of coloured noise,but also can reduce the difference between amplitude analysis results obtained from GPS and BDS deformation time series.展开更多
The pedestrian-induced lateral vibration of footbridges is essentially classified as a nonlinear stochastic vibration.Accordingly,bridge vibration stability falls within the field of nonlinear stochastic vibration sta...The pedestrian-induced lateral vibration of footbridges is essentially classified as a nonlinear stochastic vibration.Accordingly,bridge vibration stability falls within the field of nonlinear stochastic vibration stability.At present,the Lyapunov method is mainly used to analyze such stability.However,this method is qualitative,and it cannot quantitatively analyze the vibration stability probability.In this study,a new analytical method based on a comparison of the input energy and the variation of intrinsic energy(IEVIE)is used to analyze the nonlinear stochastic vibration stability of the lateral vibration of the footbridge.The improved Nakamura model is used to describe the lateral nonlinear stochastic vibration of the footbridge.A combination of the IEVIE method and the probability density evolution(PDE)method is then proposed,in which the IEVIE method is utilized to determine vibration stability.The PDE method is used to obtain the reliability of vibration stability.The proposed method is successfully applied to the Millennium Bridge,and its effectiveness is verified by comparing the Monte Carlo and Lyapunov methods.The proposed method can obtain the dynamic probability of the vibration as stable or instable and provide a reference for quantitative analysis of lateral nonlinear stochastic vibration stability of footbridges.展开更多
The paper presents the construction of a steel footbridge in the People’s Park in Lublin.The initiation and development of the architectural design of an interesting and,as it eventually turned out,aesthetically plea...The paper presents the construction of a steel footbridge in the People’s Park in Lublin.The initiation and development of the architectural design of an interesting and,as it eventually turned out,aesthetically pleasing footbridge is discussed.Two teams of architects and bridge engineers worked in parallel on the design.The design process of the footbridge structure is discussed along with its trial installation and on-site construction.The span of the footbridge is short,but its structure is innovative.For this reason its numerical model was developed used as a basis for an analysis of the dynamic response of the designed structure.The basic element of the acceptance procedure was constituted by a dynamic test load and an analysis of the pedestrian footbridge user comfort.Last but not least,the final section reviews the aesthetic canons of bridges and focuses on the footbridge in question in this context.A statistical measure of the aesthetic impression induced by a visit to the footbridge was applied resulting in a predictable and obvious final aesthetical assessment.展开更多
In order to promote the rapid development of urbanization in our country,it is necessary to improve the construction level and technology of bridge engineering.For long-span continuous bridge technology,it has the cha...In order to promote the rapid development of urbanization in our country,it is necessary to improve the construction level and technology of bridge engineering.For long-span continuous bridge technology,it has the characteristics of wide application range,various applicable conditions,and short construction period.Therefore,it is necessary to pay attention to the application of long-span continuous bridge technology.This article mainly analyzes its application in bridge construction,hoping to provide some reference for future use.展开更多
The precise control of the shape of transversely stiffened suspended cable systems is crucial. However, existing form-finding methods primarily rely on iterative calculations that treat loads as fixed known conditions...The precise control of the shape of transversely stiffened suspended cable systems is crucial. However, existing form-finding methods primarily rely on iterative calculations that treat loads as fixed known conditions. These methods are inefficient and fail to accurately control shape results. In this study, we propose a form-finding method that analyzes the load response of models under different sag and stress levels, taking into account the construction process. To analyze the system, a structural finite element model was established in ANSYS, and geometric nonlinear analysis was conducted using the Newton-Raphson method. The form-finding analysis results demonstrate that the proposed method achieves precise control of shape, with a maximum shape error ranging from 0.33% to 0.98%. Furthermore, the relationships between loads and tension forces are influenced by the deformed shape of the structures, exhibiting significant geometric nonlinear characteristics. Meanwhile, the load response analysis reveals that the stress level of the self-equilibrium state in the transversely stiffened suspended cable system is primarily governed by strength criteria, while shape is predominantly controlled by stiffness criteria. Importantly, by simulating the initial tensioning process as an initial condition, this method solves for a counterweight that satisfies the requirements and achieves a self-equilibrium state with the desired shape. The shape of the self-equilibrium state is precisely controlled by simulating the construction process. Overall, this work presents a new method for analyzing the form-finding process of large-span transversely stiffened suspended cable system, considering the construction process which was often overlooked in previous studies.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.42264004,42274033,and 41904012)the Open Fund of Hubei Luojia Laboratory(Grant Nos.2201000049 and 230100018)+2 种基金the Guangxi Universities’1,000 Young and Middle-aged Backbone Teachers Training Program,the Fundamental Research Funds for Central Universities(Grant No.2042022kf1197)the Natural Science Foundation of Hubei(Grant No.2020CFB282)the China Postdoctoral Science Foundation(Grant Nos.2020T130482,2018M630879)。
文摘The deformation monitoring of long-span railway bridges is significant to ensure the safety of human life and property.The interferometric synthetic aperture radar(In SAR)technology has the advantage of high accuracy in bridge deformation monitoring.This study monitored the deformation of the Ganjiang Super Bridge based on the small baseline subsets(SBAS)In SAR technology and Sentinel-1A data.We analyzed the deformation results combined with bridge structure,temperature,and riverbed sediment scouring.The results are as follows:(1)The Ganjiang Super Bridge area is stable overall,with deformation rates ranging from-15.6 mm/yr to 10.7 mm/yr(2)The settlement of the Ganjiang Super Bridge deck gradually increases from the bridge tower toward the main span,which conforms to the typical deformation pattern of a cable-stayed bridge.(3)The sediment scouring from the riverbed cause the serious settlement on the bridge’s east side compared with that on the west side.(4)The bridge deformation negatively correlates with temperature,with a faster settlement at a higher temperature and a slow rebound trend at a lower temperature.The study findings can provide scientific data support for the health monitoring of long-span railway bridges.
文摘In the city of Gdansk in Poland,in the very center of the Baltic capital,on 17th of June 2017,a new draw footbridge was ceremoniously opened to the public.The Olowianka footbridge represents the long-time much needed link between the highly tourist-visited historical old town and Ołowianka Island,where further cultural,tourist and recreation facilities are located.The bridge spans a very busy navigable channel of the Motława River,leading inward towards other city channels,a harbor for many tourist ships and the Gdansk Marina.Being the main navigable entrance to the city center,the Motława is constantly under nautical traffic,so the Ołowianka footbridge operates 24/7,according to a 30-min schedule.The Ołowianka footbridge is an extraordinary acquisition for the city of Gdansk,which immediately became a new landmark and much more in the already very picturesque historic city center.Not just its design,but also its carefully chosen location and its realization at the right moment,has made this bridge indispensable to the inhabitants,visitors and the administration of the city of Gdansk,decisively contributing to further development in the Ołowianka Island area and its surroundings.
基金This research was supported by the National Natural Science Foundation of China(No.51608207)the Natural Science Foundation of Guangdong Province,China(No.2019A1515011941).
文摘Research on the lateral vibrational stability of footbridges has attracted increasing attention in recent years. However, this stability contains a series of complex mechanisms, such as nonlinear vibration, random excitation, andrandom stability. The Lyapunov method is regarded as an effective tool for analyzing random vibrational stability;however, it is a qualitative method and can only provide a binary judgment for stability. This study proposes anew method, IEVIE–SA, which combines the energy method based on the comparison between the input energyand the variation of intrinsic energy (IEVIE) and the stochastic averaging (SA) method. The improved Nakamuramodel was used to describe the lateral nonlinear stochastic vibration of a footbridge, whereby the IEVIE methodwas used to establish the criteria for judging the lateral vibrational stability. Additionally, the SA method was usedto deduce the corresponding backward Kolmogorov equation. Subsequently, the backward Kolmogorov equationwas combined with the stability criterion established by the IEVIE method to analyze the first passage stability. Theproposed method is a semi-analytical, quantitative method that only requires a small calculation. By applying theproposed method to the Millennium Bridge, method effectiveness was verified by comparing it with the MonteCarlo and traditional Lyapunov methods.
基金the National Key Research and Development Program under Grant 2021YFB2600400the Science And Technology Project For China Railway Construction Corporation Limited under Grant 2022-A 02,Wuhan Enterprise Technology Innovation Project under Grant 2019010702011314+4 种基金Guangxi Science And Technology Plan Project under Grant AD19110107Guangxi Natural Science Foundation under Grant 2018GXNSFBA050006the Project To Improve The Basic Research Ability Of Young And MiddleAged Teachers In Guangxi Universities under Grant 2020KY06032Urban Spatial Information Engineering Beijing Key Laboratory Funded Project under Grant number 2020217Natural Science Foundation of Hubei Province under Grant 2020CFB282,National Natural Science Foundation of China under Grant 42264004.
文摘Combining GPS and BDS technology to monitor the deformation of long-span railway bridges with stricter deformation control requirements is of significance to the safety and control of the bridge and the safety of railway traffic.Previous studies have ignored the influence of coloured noise in the deformation time series.This is not conducive to accurate deformation analysis of long-span railway bridges.Therefore,GPS,BDS and GPS/BDS monitoring data of Ganjiang Bridge located in Ganzhou city,Jiangxi Province,China are adopted in this paper to filter the coloured noise in the deformation time series by principal component analysis(PCA),and the influence of coloured noise on the deformation analysis results of railway bridge is analysed.The experimental results show that the diurnal temperature difference causes the mid-span and the tower of the railway cable-stayed bridge to deform with a period of about one day in the vertical and longitudinal directions,respectively.Ignoring colored noise will make the uncertainty of the deformation parameter estimation overly optimistic.PCA can significantly reduce the coloured noise,and thus reduce the uncertainty of deformation parameter estimation by about 73%.Moreover,the average difference between the daily periodic motion amplitudes of the monitoring points obtained by using GPS and BDS deformation time series is 1.65 mm.The use of GPS/BDS deformation time series is not only helpful to reduce the influence of coloured noise,but also can reduce the difference between amplitude analysis results obtained from GPS and BDS deformation time series.
基金National Natural Science Foundation of China under Grant No.51608207,the Natural Science Foundation of Guangdong Province,China under Grant No.2019A1515011941,and China Scholarship Council under Grant Nos.201806155102 and 201906155028。
文摘The pedestrian-induced lateral vibration of footbridges is essentially classified as a nonlinear stochastic vibration.Accordingly,bridge vibration stability falls within the field of nonlinear stochastic vibration stability.At present,the Lyapunov method is mainly used to analyze such stability.However,this method is qualitative,and it cannot quantitatively analyze the vibration stability probability.In this study,a new analytical method based on a comparison of the input energy and the variation of intrinsic energy(IEVIE)is used to analyze the nonlinear stochastic vibration stability of the lateral vibration of the footbridge.The improved Nakamura model is used to describe the lateral nonlinear stochastic vibration of the footbridge.A combination of the IEVIE method and the probability density evolution(PDE)method is then proposed,in which the IEVIE method is utilized to determine vibration stability.The PDE method is used to obtain the reliability of vibration stability.The proposed method is successfully applied to the Millennium Bridge,and its effectiveness is verified by comparing the Monte Carlo and Lyapunov methods.The proposed method can obtain the dynamic probability of the vibration as stable or instable and provide a reference for quantitative analysis of lateral nonlinear stochastic vibration stability of footbridges.
文摘The paper presents the construction of a steel footbridge in the People’s Park in Lublin.The initiation and development of the architectural design of an interesting and,as it eventually turned out,aesthetically pleasing footbridge is discussed.Two teams of architects and bridge engineers worked in parallel on the design.The design process of the footbridge structure is discussed along with its trial installation and on-site construction.The span of the footbridge is short,but its structure is innovative.For this reason its numerical model was developed used as a basis for an analysis of the dynamic response of the designed structure.The basic element of the acceptance procedure was constituted by a dynamic test load and an analysis of the pedestrian footbridge user comfort.Last but not least,the final section reviews the aesthetic canons of bridges and focuses on the footbridge in question in this context.A statistical measure of the aesthetic impression induced by a visit to the footbridge was applied resulting in a predictable and obvious final aesthetical assessment.
文摘In order to promote the rapid development of urbanization in our country,it is necessary to improve the construction level and technology of bridge engineering.For long-span continuous bridge technology,it has the characteristics of wide application range,various applicable conditions,and short construction period.Therefore,it is necessary to pay attention to the application of long-span continuous bridge technology.This article mainly analyzes its application in bridge construction,hoping to provide some reference for future use.
文摘The precise control of the shape of transversely stiffened suspended cable systems is crucial. However, existing form-finding methods primarily rely on iterative calculations that treat loads as fixed known conditions. These methods are inefficient and fail to accurately control shape results. In this study, we propose a form-finding method that analyzes the load response of models under different sag and stress levels, taking into account the construction process. To analyze the system, a structural finite element model was established in ANSYS, and geometric nonlinear analysis was conducted using the Newton-Raphson method. The form-finding analysis results demonstrate that the proposed method achieves precise control of shape, with a maximum shape error ranging from 0.33% to 0.98%. Furthermore, the relationships between loads and tension forces are influenced by the deformed shape of the structures, exhibiting significant geometric nonlinear characteristics. Meanwhile, the load response analysis reveals that the stress level of the self-equilibrium state in the transversely stiffened suspended cable system is primarily governed by strength criteria, while shape is predominantly controlled by stiffness criteria. Importantly, by simulating the initial tensioning process as an initial condition, this method solves for a counterweight that satisfies the requirements and achieves a self-equilibrium state with the desired shape. The shape of the self-equilibrium state is precisely controlled by simulating the construction process. Overall, this work presents a new method for analyzing the form-finding process of large-span transversely stiffened suspended cable system, considering the construction process which was often overlooked in previous studies.
