In general, two kinds of structures are used to provide a way across a river, canal, sea, or other obstacle: bridge structures that pass over the obstacle, and tunnel structures that pass below the obstacle. Although ...In general, two kinds of structures are used to provide a way across a river, canal, sea, or other obstacle: bridge structures that pass over the obstacle, and tunnel structures that pass below the obstacle. Although the construction of both bridges and tunnels can be traced back over thousands of years, bridge–tunnel combinations that use an island as a sea-crossing fixed link (SCFL) have only been built over the past 82 years. The first such combination was probably the 6.4 km long San Francisco–Oakland Bay Bridge in the United States, which was completed in 1936. The most recently constructed SCFL combining a bridge, tunnel, and island is the Hong Kong–Zhuhai–Macao (HZM) Bridge, which opened for traffic on October 24, 2018 with the longest SCFL combination in the world, at a total length of 29.6 km.展开更多
According to the relationship between load and response, the equivalent static wind load(ESWL) of a structure can be estimated by load-response correlation(LRC) method, which can be accurately used to estimate the bac...According to the relationship between load and response, the equivalent static wind load(ESWL) of a structure can be estimated by load-response correlation(LRC) method, which can be accurately used to estimate the background ESWL of a structure. The derivation of the classical expression of LRC formula is based on a specific command response at a critical position, and the ESWL distribution has only one form in this case. In this paper, a general expression of LRC formula is derived based on a specific command response at all positions. For the general expression, ESWLs can be expressed by load-response correlation coefficients, response-response correlation coefficients, RMS values of the fluctuating wind loads, and peak factor in the form of matrices. By comparing the expressions of LRC method, it was found that the classical expression was only one form of the general one. The general expression which introduces the response-response correlation coefficients provided more options for structural engineers to estimate ESWLs and offered further insights into the LRC method. Finally, a cable-stayed bridge, a rigid three span continuous girder bridge, and a suspension bridge were used to verify the correctness of the general expression of LRC method.展开更多
Humans have historically built various kinds of bridges, including girder, arch, cable-stayed, and suspension bridges, in order to cross streams, rivers, and valleys. Although the bridges that were built in ancient ti...Humans have historically built various kinds of bridges, including girder, arch, cable-stayed, and suspension bridges, in order to cross streams, rivers, and valleys. Although the bridges that were built in ancient times were small and primitive, they were bridges nonetheless.展开更多
The concept of sustainability is described in this paper using a single sustainable principle,two goals of sustainable development,three dimensions of sustainable engineering,four sustainable requirements and five pha...The concept of sustainability is described in this paper using a single sustainable principle,two goals of sustainable development,three dimensions of sustainable engineering,four sustainable requirements and five phases of sustainable construction.Four sustainable requirements and their practice in China are discussed in particular.The safe reliability of bridges is first compared with the events of bridge failure in China and in the rest of the world and followed by structural durability,including the cracking of concrete cable-stayed bridges,deflection of concrete girder bridges and fatigue cracks of orthotropic steel decks.With respect to functional adaptability,lateral wind action on vehicles and its improvement are introduced regarding a sea-crossing bridge located in a typhoon-prone area.The Chinese practice of using two double main span suspension bridges and a twin parallel deck cable-stayed bridge is presented in discussing the final sustainable requirement:capacity extensibility.展开更多
Aerodynamic instability owing to aerostatic and flutter-related failures is a significant concern in the wind-resistant design of long-span suspension bridges.Based on the dynamic characteristics of suspension bridges...Aerodynamic instability owing to aerostatic and flutter-related failures is a significant concern in the wind-resistant design of long-span suspension bridges.Based on the dynamic characteristics of suspension bridges with spans ranging from 888 to 1991 m,we proposed fitted equations for increasing spans and base frequencies.Finite element models of suspension bridges with increasing span from 1000 to 5000 m were constructed.The structural parameters were optimized to follow the fitted tendencies.To analyze the aerodynamic instability,streamlined single-box section(SBS),lattice truss section(LTS),narrow slotted section(NSS),and wide slotted section(WSS)were considered.We performed three-dimensional(3-D)full-mode flutter analysis and nonlinear aerostatic instability analysis.The flutter critical wind speed continuously decreases with span growth,showing an unlimited approaching phenomenon.Regarding aerostatic instability,the instability wind speed decreases with span to approximately 3000 m,and increases when the span is in the range of 3000 to 5000 m.Minimum aerostatic instability wind speed with SBS or LTS girder would be lower than observed maximal gust wind speed,indicating the probability of aerostatic instability.This study proposes that suspension bridge with span approximately 3000 m should be focused on both aerostatic instability and flutter,and more aerodynamic configuration optimistic optimizations for flutter are essential for super long-span suspension bridges with spans longer than 3000 m.展开更多
It is necessary to study how vehicles influence the vortex-excited resonance of vehicle-bridge systems,because lock-in wind speed is low and vortex-excited resonance is sensitive to any change in the main girder secti...It is necessary to study how vehicles influence the vortex-excited resonance of vehicle-bridge systems,because lock-in wind speed is low and vortex-excited resonance is sensitive to any change in the main girder sections.Based on the Shanghai Bridge over the Yangtse River,the vortex-excited resonance of a 1∶60 scale sectional model was tested in a TJ-1wind tunnel,with or without vehicles at the attack angle of 0°,+3 and–3°,respectively.The conversion relationships between the resonant amplitudes of the sectional model and that of the prototype bridge were also established by mode shape correction.The result indicates that:1)for the bridge with vehicles,the vertical vortex-excited resonance is accompanied by torsion vibration with the same frequency,and vice versa,2)the amplitude of vortex-excited resonance of the bridge with vehicles is much larger than that of the bridge without vehicles,and 3)the lock-in wind speed of the vortex-excited resonance becomes smaller due to the disturbance of vehicles.It is obvious that vehicles bring about changes in the aerodynamic shape of the main girder.Therefore,the influence of vehicles on vortex-excited resonance performance of vehicle-bridge systems,in terms of both amplitude and mode,should not be ignored.展开更多
This paper reviews wind loading codes and standards in the Asia-Pacific Region,in particular in the 15 countries and areas.A general description of wind loading model is given as a famous wind loading chain described ...This paper reviews wind loading codes and standards in the Asia-Pacific Region,in particular in the 15 countries and areas.A general description of wind loading model is given as a famous wind loading chain described by four variables including velocity pressure,exposure factor,pressure coefficient,and gust response factor.Through the APEC-WW Workshops and the extensive calculations for three examples of low,medium and high rise buildings,these four important variables of wind loads are evaluated and compared with statistical parameters,mean values and coefficients of variation.The main results of the comparison show some differences among the 15 economies,and the reasons and further incorporation are discussed and suggested.展开更多
文摘In general, two kinds of structures are used to provide a way across a river, canal, sea, or other obstacle: bridge structures that pass over the obstacle, and tunnel structures that pass below the obstacle. Although the construction of both bridges and tunnels can be traced back over thousands of years, bridge–tunnel combinations that use an island as a sea-crossing fixed link (SCFL) have only been built over the past 82 years. The first such combination was probably the 6.4 km long San Francisco–Oakland Bay Bridge in the United States, which was completed in 1936. The most recently constructed SCFL combining a bridge, tunnel, and island is the Hong Kong–Zhuhai–Macao (HZM) Bridge, which opened for traffic on October 24, 2018 with the longest SCFL combination in the world, at a total length of 29.6 km.
基金Sponsored by the National Natural Science Foundation of China(Grant No.51508107)the China Postdoctoral Science Foundation(Grant No.2016M590592)the Natural Science Foundation of Fujian Province(Grant No.2015J05098)。
文摘According to the relationship between load and response, the equivalent static wind load(ESWL) of a structure can be estimated by load-response correlation(LRC) method, which can be accurately used to estimate the background ESWL of a structure. The derivation of the classical expression of LRC formula is based on a specific command response at a critical position, and the ESWL distribution has only one form in this case. In this paper, a general expression of LRC formula is derived based on a specific command response at all positions. For the general expression, ESWLs can be expressed by load-response correlation coefficients, response-response correlation coefficients, RMS values of the fluctuating wind loads, and peak factor in the form of matrices. By comparing the expressions of LRC method, it was found that the classical expression was only one form of the general one. The general expression which introduces the response-response correlation coefficients provided more options for structural engineers to estimate ESWLs and offered further insights into the LRC method. Finally, a cable-stayed bridge, a rigid three span continuous girder bridge, and a suspension bridge were used to verify the correctness of the general expression of LRC method.
文摘Humans have historically built various kinds of bridges, including girder, arch, cable-stayed, and suspension bridges, in order to cross streams, rivers, and valleys. Although the bridges that were built in ancient times were small and primitive, they were bridges nonetheless.
基金The work described in this paper is partially supported by the Natural Science Foundation of China(Grant Nos.90715039 and 51021140005)by the Ministry of Science and Technology of China(Grant Nos.2006AA11Z108 and 2008BAG07B02).
文摘The concept of sustainability is described in this paper using a single sustainable principle,two goals of sustainable development,three dimensions of sustainable engineering,four sustainable requirements and five phases of sustainable construction.Four sustainable requirements and their practice in China are discussed in particular.The safe reliability of bridges is first compared with the events of bridge failure in China and in the rest of the world and followed by structural durability,including the cracking of concrete cable-stayed bridges,deflection of concrete girder bridges and fatigue cracks of orthotropic steel decks.With respect to functional adaptability,lateral wind action on vehicles and its improvement are introduced regarding a sea-crossing bridge located in a typhoon-prone area.The Chinese practice of using two double main span suspension bridges and a twin parallel deck cable-stayed bridge is presented in discussing the final sustainable requirement:capacity extensibility.
基金support of National Key R&D Program of China(No.2022YFC3004105)National Natural Science Foundation of China(Grant Nos.52078383,52008314,52108469).
文摘Aerodynamic instability owing to aerostatic and flutter-related failures is a significant concern in the wind-resistant design of long-span suspension bridges.Based on the dynamic characteristics of suspension bridges with spans ranging from 888 to 1991 m,we proposed fitted equations for increasing spans and base frequencies.Finite element models of suspension bridges with increasing span from 1000 to 5000 m were constructed.The structural parameters were optimized to follow the fitted tendencies.To analyze the aerodynamic instability,streamlined single-box section(SBS),lattice truss section(LTS),narrow slotted section(NSS),and wide slotted section(WSS)were considered.We performed three-dimensional(3-D)full-mode flutter analysis and nonlinear aerostatic instability analysis.The flutter critical wind speed continuously decreases with span growth,showing an unlimited approaching phenomenon.Regarding aerostatic instability,the instability wind speed decreases with span to approximately 3000 m,and increases when the span is in the range of 3000 to 5000 m.Minimum aerostatic instability wind speed with SBS or LTS girder would be lower than observed maximal gust wind speed,indicating the probability of aerostatic instability.This study proposes that suspension bridge with span approximately 3000 m should be focused on both aerostatic instability and flutter,and more aerodynamic configuration optimistic optimizations for flutter are essential for super long-span suspension bridges with spans longer than 3000 m.
文摘It is necessary to study how vehicles influence the vortex-excited resonance of vehicle-bridge systems,because lock-in wind speed is low and vortex-excited resonance is sensitive to any change in the main girder sections.Based on the Shanghai Bridge over the Yangtse River,the vortex-excited resonance of a 1∶60 scale sectional model was tested in a TJ-1wind tunnel,with or without vehicles at the attack angle of 0°,+3 and–3°,respectively.The conversion relationships between the resonant amplitudes of the sectional model and that of the prototype bridge were also established by mode shape correction.The result indicates that:1)for the bridge with vehicles,the vertical vortex-excited resonance is accompanied by torsion vibration with the same frequency,and vice versa,2)the amplitude of vortex-excited resonance of the bridge with vehicles is much larger than that of the bridge without vehicles,and 3)the lock-in wind speed of the vortex-excited resonance becomes smaller due to the disturbance of vehicles.It is obvious that vehicles bring about changes in the aerodynamic shape of the main girder.Therefore,the influence of vehicles on vortex-excited resonance performance of vehicle-bridge systems,in terms of both amplitude and mode,should not be ignored.
基金This study was partially supported by the Natural Science Foundation of China(Grant Nos.90715039 and 51021140005)the grant SLDRCE09-A-01.
文摘This paper reviews wind loading codes and standards in the Asia-Pacific Region,in particular in the 15 countries and areas.A general description of wind loading model is given as a famous wind loading chain described by four variables including velocity pressure,exposure factor,pressure coefficient,and gust response factor.Through the APEC-WW Workshops and the extensive calculations for three examples of low,medium and high rise buildings,these four important variables of wind loads are evaluated and compared with statistical parameters,mean values and coefficients of variation.The main results of the comparison show some differences among the 15 economies,and the reasons and further incorporation are discussed and suggested.
