Purpose–The bridge expansion joint(BEJ)is a key device for accommodating spatial displacement at the beam end,and for providing vertical support for running trains passing over the gap between the main bridge and the...Purpose–The bridge expansion joint(BEJ)is a key device for accommodating spatial displacement at the beam end,and for providing vertical support for running trains passing over the gap between the main bridge and the approach bridge.For long-span railway bridges,it must also be coordinated with rail expansion joint(REJ),which is necessary to accommodate the expansion and contraction of,and reducing longitudinal stress in,the rails.The main aim of this study is to present analysis of recent developments in the research and application of BEJs in high-speed railway(HSR)long-span bridges in China,and to propose a performance-based integral design method for BEJs used with REJs,from both theoretical and engineering perspectives.Design/methodology/approach–The study first presents a summary on the application and maintenance of BEJs in HSR long-span bridges in China representing an overview of their state of development.Results of a survey of typical BEJ faults were analyzed,and field testing was conducted on a railway cable-stayed bridge in order to obtain information on the major mechanical characteristics of its BEJ under train load.Based on the above,a performance-based integral design method for BEJs with maximum expansion range 1600 mm(±800 mm),was proposed,covering all stages from overall conceptual design to consideration of detailed structural design issues.The performance of the novel BEJ design thus derived was then verified via theoretical analysis under different scenarios,full-scale model testing,and field testing and commissioning.Findings–Two major types of BEJs,deck-type and through-type,are used in HSR long-span bridges in China.Typical BEJ faults were found to mainly include skewness of steel sleepers at the bridge gap,abnormally large longitudinal frictional resistance,and flexural deformation of the scissor mechanisms.These faults influence BEJ functioning,and thus adversely affect track quality and train running performance at the beam end.Due to their simple and integral structure,deck-type BEJs with expansion range 1200 mm(±600 mm)or less have been favored as a solution offering improved operational conditions,and have emerged as a standard design.However,when the expansion range exceeds the above-mentioned value,special design work becomes necessary.Therefore,based on engineering practice,a performance-based integral design method for BEJs used with REJs was proposed,taking into account four major categories of performance requirements,i.e.,mechanical characteristics,train running quality,durability and insulation performance.Overall BEJ design must mainly consider component strength and the overall stiffness of BEJ;the latter factor in particular has a decisive influence on train running performance at the beam end.Detailed BEJ structural design must stress minimization of the frictional resistance of its sliding surface.The static and dynamic performance of the newlydesigned BEJ with expansion range 1600 mm have been confirmed to be satisfactory,via numerical simulation,full-scale model testing,and field testing and commissioning.Originality/value–This research provides a broad overview of the status of BEJs with large expansion range in HSR long-span bridges in China,along with novel insights into their design.展开更多
Damage alarming and safety evaluation using long-term monitoring data is an area of significant research activity for long-span bridges. In order to extend the research in this field, the damage alarming technique for...Damage alarming and safety evaluation using long-term monitoring data is an area of significant research activity for long-span bridges. In order to extend the research in this field, the damage alarming technique for bridge expansion joints based on long-term monitoring data was developed. The effects of environmental factors on the expansion joint displacement were analyzed. Multiple linear regression models were obtained to describe the correlation between displacements and the dominant environmental factors. The damage alarming index was defined based on the multiple regression models. At last, the X-bar control chart was utilized to detect the abnormal change of the displacements. Analysis results reveal that temperature and traffic condition are the dominant environmental factors to influence the displacement. When the confidence level of X-bar control chart is set to be 0.003, the false-positive indications of damage can be avoided. The damage sensitivity analysis shows that the proper X-bar control chart can detect 0.1 cm damage-induced change of the expansion joint displacement. It is reasonably believed that the proposed technique is robust against false-positive indication of damage and suitable to alarm the possible future damage of the expansion joints.展开更多
The expansion joints are expected to have movement capacity, bearing capacity for static and dynamic loading, water-tightness, low noise emission and traffic safety. In particular, the failure due to impact loading is...The expansion joints are expected to have movement capacity, bearing capacity for static and dynamic loading, water-tightness, low noise emission and traffic safety. In particular, the failure due to impact loading is the main reason for the observed damages. The problem of dynamic behavior of the expansion joints is so complex that we shall focus our attention on the impact factor for vehicle load that is governed by traffic impact. In order to overcome this difficulty, the cantilever-toothed aluminum joint (finger joint) is one of the promising joints under impact loading. In this study, from the viewpoint of design methodology, numerical studies for impact behavior were conducted for aluminum alloy expansion joints with perforated dowels. The design impact factor for the expansion joints with the perforated dowels against traffic impact loading was examined by using numerical simulations.展开更多
Expansion joints silicone sealants used in high speed railway construction suffer from ultraviolet radiation（UV）, high temperature combined with the alkaline environment. To evaluate the durability and analyse the a...Expansion joints silicone sealants used in high speed railway construction suffer from ultraviolet radiation（UV）, high temperature combined with the alkaline environment. To evaluate the durability and analyse the ageing mechanism, six one-component silicone sealants from different companies were selected and subjected to accelerated ageing tests including UV, thermal and alkali ageing treatments. The ageing effects on the performance of the sealants were evaluated via the appearance and the mechanical property changes. The changes in molecular structure were studied by means of Fourier transform infrared spectroscopy（FTIR）, differential scanning calorimetry（DSC） and thermogravimetry（TG）. This study revealed that different materials displayed different sensibilities to the ageing methods, in which 15 %-20 % decreases of mechanical properties could be observed under UV radiation test, owning the most significant effects. Structure analysis showed that the physical changes of aggregative states were the principal factors to the performance, along with the chemical slight changes. The glossiness dropped significantly in ageing test, which could be used as one of the effective evaluation parameters for ageing conditions in the field.展开更多
The influence of expansion joints on the welding residual stress at the tube-plate junction of an exhaust gas recirculation(EGR)cooler was studied by numerical simulation method.The simulation results show that the ex...The influence of expansion joints on the welding residual stress at the tube-plate junction of an exhaust gas recirculation(EGR)cooler was studied by numerical simulation method.The simulation results show that the expansion joints set on the housing of the EGR cooler mainly for the sake of protecting the tube-plate joints from bearing additional heating stress can also reduce the welding residual tensile stress.The expansion joints set on the EGR cooler can mitigate the tensile force acting on the edges of the main plates through its elastic extension,and thus reduce the magnitude of welding residual tensile stress at the tube-plate junction.展开更多
In design phases, expansion joints are required to have movement capacity, bearing capacity for static and dynamic loading, watertight, low noise emission and traffic safety. On the basis of the fact that failure due ...In design phases, expansion joints are required to have movement capacity, bearing capacity for static and dynamic loading, watertight, low noise emission and traffic safety. On the basis of the fact that failure due to dynamic loading is the main reason for the observed damages, attention is focused on the bearing capacity for dynamic loading governed by impact, because it differs from the static loading. In this study, from the viewpoint of durability, experimental studies for dynamic behavior were conducted for aluminium alloy expansion joints with perforated dowels. The validity of the perforated dowels against traffic impact loading was confirmed by both experimental and numerical studies.展开更多
The article summarizes related research results and achievements of elastomer expansion device in railway bridge and puts forward a new idea of using polyurethane elastomer material to seal concrete bridge joints betw...The article summarizes related research results and achievements of elastomer expansion device in railway bridge and puts forward a new idea of using polyurethane elastomer material to seal concrete bridge joints between adjacent spans in heavy haul railways. The new type expansion device is composed of polyurethane elastomer material and named TTXF （elastomer expansion joint）. In theory, researchers find out expansion joint deformation regularity between adjacent bridge spans through theoretical analysis and detection in heavy haul railways, such as Datong-Qinhuangdao Railway and Shenchi-Huanghua Port Railway. Fatigue tests prove that TTXF can adapt to permanent and dynamic deformation. On the other hand, it has been successfully applied in the test section of Central South of Shanxi Railway Passage and continuous monitoring has been conducted in extreme weather for over one year. The expansion joint has a good effect practically.展开更多
In Well MJ4,Tarim Basin,the testing tubing string is 6617 m long and the bottom-hole pressure during the testing is 101.63 MPa.During the completion job,plastic deformation occurs in the tubing string,so it is very ne...In Well MJ4,Tarim Basin,the testing tubing string is 6617 m long and the bottom-hole pressure during the testing is 101.63 MPa.During the completion job,plastic deformation occurs in the tubing string,so it is very necessary to figure out at which stage of the completion job plastic deformation occurs on earth.For this reason,the three-dimension finite element analysis method was used to perform numerical calculations for the deformation of tubing string and the distribution of axial stress based on three typical load conditions(setting load,fracturing load,and well testing load of Well MJ4);a process for calculating the mechanical behavior of a completion and testing tubing string containing an expansion joint was then developed.The study content mainly includes:(1)A criterion was developed to determine the extension and closure status of the expansion joint in the tubing string;corresponding calculation mechanism and formulae were provided;and the extensioneclosure status of the expansion joint in the tubing string for Well MJ4 was calculated.(2)A method was developed for analyzing and calculating the additional pressure difference load in the packer annulus caused by poor engagement of the hydraulic anchor;the impact of the additional pressure difference load on the deformation behavior of the tubing string was simulated;and the significant impact of the additional pressure difference load on the plastic buckling deformation was figured out.(3)The limit of lateral buckling deformation in a calculation model was introduced,and so the impact of collar rigidity on the buckling deformation was indirectly considered;the deformation under the joint action of all loads of the tubing string was calculated,and the numerical result was the same as the observed deformation.The study results show that the plastic deformation of the tubing string for Well MJ4 occurs at the fracturing stage and the major causes are hydraulic pressure loads and gravity loads in different forms.The conclusion shows that the mechanical calculation model of the testing tubing containing the expansion joint can be used as an important theoretical tool and analysis approach in optimizing operations and designing the tubing string structure.展开更多
Expansion joint construction is an important part of road and bridge engineering. Good construction quality control of this link plays an important role in improving the construction quality of the whole project. Expa...Expansion joint construction is an important part of road and bridge engineering. Good construction quality control of this link plays an important role in improving the construction quality of the whole project. Expansion joint construction technology is not closed, not only will affect the whole project, there will be a lot of fatal security risks. In road and bridge construction, expansion joint construction technology is related to bridge deformation. Reasonable research on construction technology of road and bridge expansion joints can not only avoid cracks, but also fundamentally improve the reliability and safety of road and bridge engineering. Next, the article discusses the expansion joint construction technology in road and bridge engineering.展开更多
This paper addresses the problem of condition assessment of bridge expansion joints using long-term measurement data under changing environmental conditions.The effects of temperature,traffic loading and wind on the e...This paper addresses the problem of condition assessment of bridge expansion joints using long-term measurement data under changing environmental conditions.The effects of temperature,traffic loading and wind on the expansion joint displacements are analyzed and interpreted,which reveal that measured displacements are observed to increase with an increase in temperature and to decrease with increased traffic loading,while the correlation between displacement and wind speed is very weak.Two regression models are developed to simulate the varying displacements under the changes in temperature and traffic loadings.Based on these models,the effects of the environmental conditions are removed to obtain the normalized displacement.Statistical process control using mean value control charts is further used to detect damage to the bridge expansion joints.The results reveal that the proposed method had a good capability for detecting the damage-induced 1.0%variances of the annual changes in the expansion joint displacements.展开更多
BASF and Sinopec began the construction for the expansion of their joint venture,BASF-YPC Co.,Ltd. (BYC). BASF and Sinopec plan to jointly invest approximately $1.4 billion
The complex bridge-track interaction between kilometer-span bridges and continuous Welded Rail(CWR)brings great challenges to CWR designing.Taking a suspension bridge with laying CWR as a case,the mechanical propertie...The complex bridge-track interaction between kilometer-span bridges and continuous Welded Rail(CWR)brings great challenges to CWR designing.Taking a suspension bridge with laying CWR as a case,the mechanical properties of CWR on the bridge are analyzed to reveal the sensitive areas of the track,and the design method of CWR and track structures on the beam ends are proposed.The results show that the unidirectional Rail Expansion Joints(REJ)need to be installed on the beam end of the kilometer-span bridge to reduce rail longitudinal force.Due to the bridge characteristics,there is no CWR fixed area on the kilometer-span bridge,and rail longitudinal force on the main span caused by bending loads needs to be concerned.The deformation of track on the beam end is complex,which is the weak area on the kilometer bridge,the large relative displacement between the stock rail of REJ and the main beam can cause poor stability of ballast bed on beam end,small resistance fasteners need to be laid on the sides of stock rail on the main beam to increase the stability of ballast and fasteners on the beam end.To improve the driving safety and comfort of beam end,the Sleeper-Supporting Apparatus(SSA)should be specially designed to ensure the uniform transition of track on beam ends.Temperature and wind loads have a significant impact on track regularity on the kilometer span bridge,the dynamic response of trains and bridges under those loads needs to be attended to.展开更多
Stress concentration occurs in the foundations of railway tracks where discontinuous components are located.The exacerbated stress under the expansion joints in slab tracks may trigger foundation failures such as mud ...Stress concentration occurs in the foundations of railway tracks where discontinuous components are located.The exacerbated stress under the expansion joints in slab tracks may trigger foundation failures such as mud pumping.Although the higher stress due to the discontinuities of track structures has been discussed in past studies,few focused on the stress response of roadbeds in slab tracks and quantitatively characterized the stress pattern.In this paper,we performed a dynamic finite element analysis of a track-formation system,incorporating expansion joints as primary longitudinal discontinuities.The configurations of CRTS Ⅲ slab tracks and the contact conditions between concrete layers were considered.Numerical results show that longitudinal influencing length of induced stress on roadbed under wheel load relates to the contact conditions between concrete layers,increasing nonlinearly at a larger coefficient of friction.Given a measured coefficient of friction of 0.7,the calculated longitudinal influencing length(9.0 m) matches with field data.The longitudinal influencing length is not affected with the increasing velocity.As stress concentration arises with expansion joints,the worstcase scenario emerges when double-axle loads are exerted immediately above the expansion joints between concrete bases.A stress concentration factor Cvon the roadbed is proposed;it increases with the increasing velocity,changing from 1.33 to 1.52 at velocities between 5 and 400 km/h.The stress distribution on roadbeds transforms from a trapezoid pattern at continuous sections to a triangle pattern at points with longitudinal discontinuities.An explicit expression is finally proposed for the stress pattern on roadbed under expansion joints.Although structural discontinuities induce stress raiser,the extent of concentration is mitigated with increasing depth at different velocity levels.展开更多
With the continuous development of bridge and tunnel construction technologies,large-scale sea-crossing bridges and tunnels have gradually become the preferred choice for regional traffic.The construction technology o...With the continuous development of bridge and tunnel construction technologies,large-scale sea-crossing bridges and tunnels have gradually become the preferred choice for regional traffic.The construction technology of Hong Kong-Zhuhai-Macao Bridge(HZMB),one of the most representative sea-crossing passageways,is instructive for the construction of other large sea-crossing infrastructures.At present,the pavement design method of sea-crossing passageways lacks pertinence as it still refers to specifications for design of common pavement.Therefore,it is necessary to consider the bridge and tunnel pavement of HZMB as a typical example to analyze key technical problems encountered in its design,construction and operation.Novel solutions for material selection and structural design built upon the analysis of such critical problems should thus follow up.Based on comprehensive literature research,it can be found that environmental variability,tunnel closure,structural differential settlement and expansion deformation are the key technical problems faced by pavement of sea-crossing passageways.In view of the environmental variability,the steel deck-paving material and structure design of GMA-10 t SMA-13 is innovatively proposed.As for the closure of immersed tube tunnel,warm-mix flame retardant asphalt mixture is used to control pavement design through key indexes such as temperature and limit oxygen index.Regarding the deformation of immersed pipe joints,BJ200 asphalt seamless expansion joint material is introduced,which effectively satisfies the multi-directional deformation between pipe joints and ensures the smoothness of the road surface and driving comfort.For segmental joints,double-layer waterproof-coiled material is used to effectively prevent reflective cracks while ensuring the continuity of asphalt concrete pavement.Therefore,this paper provides a panel of ideas and methods for the pavement design of the same type of sea-crossing passageways.展开更多
In ITER facilities, there are some special expansion joints connected with the openings of cryostat. Expect for the assemblies connected with NB openings, others are rectangular section with big dimensions and severe ...In ITER facilities, there are some special expansion joints connected with the openings of cryostat. Expect for the assemblies connected with NB openings, others are rectangular section with big dimensions and severe working conditions and they are important for ITER safe runing.展开更多
A long-span concrete-filled steel tubular(CFST)arch bridge suffers severe vehicle-induced dynamic responses during its service life.However,few quantitative studies have been reported on the typical diseases suffered ...A long-span concrete-filled steel tubular(CFST)arch bridge suffers severe vehicle-induced dynamic responses during its service life.However,few quantitative studies have been reported on the typical diseases suffered by such bridges and their effects on vehicle-induced dynamic response.Thus,a series of field tests and theoretical analyses were conducted to study the effects of typical diseases on the vehicle-induced dynamic response of a typical CFST arch bridge.The results show that a support void results in a height difference between both sides of the expansion joint,thus increasing the effect of vehicle impact on the main girder and suspenders.The impact factor of the displacement response of the main girder exceeds the design value.The variation of the suspender force is significant,and the diseases are found to have a greater effect on a shorter suspender.The theoretical analysis results also show that the support void causes an obvious longitudinal displacement of the main girder that is almost as large as the vertical displacement.The support void can also cause significant changes in the vehicle-induced acceleration response,particularly when the supports and steel box girder continue to collide with each other under the vehicle load.展开更多
This study describes a developing process of lifeline earthquake engineering from historical aspects.Currently various seismic design methods have been furnished for ground shaking and for permanent ground displacemen...This study describes a developing process of lifeline earthquake engineering from historical aspects.Currently various seismic design methods have been furnished for ground shaking and for permanent ground displacement.The seismic design method for ground shaking introduces different travelling wave models in the US and in Japan.As a result,Japanese approach was developed by actively taking into account the slippage effect in order to solve the inelastic response of the pipeline for a severe earthquake.The seismic design method for permanent ground displacement,on the other hand,prepared various numerical modeling and database in the US,while the simplified design formula for ground displacement was furnished in the seismic design guidelines in Japan.The detail design formula for liquefied ground settlement and fault displacement are expressed in this study.Various approaches of the performance-based seismic design method are compared among EU,the US and Japan.Unfortunately,the design method in Japan does not show the safety target in the guidelines.Then a simple evaluation approach to obtain the safety index is proposed herein.The different performance of two actual pipeline systems is compared,in which one pipeline system demonstrated a good performance for 2011 East Japan Great Earthquake,and the other did not.In state-of-the-art study,the seismic experiments and design method of expansion joints are described,because the ultimate limit performance of the expansion joints has not been explicit,although many seismic damages have occurred at the locations of vulnerable expansion joints.展开更多
基金National Key R&D Program of China(2022YFB2602900)R&D Fund Project of China Academy of Railway Sciences Corporation Limited(2021YJ084)+2 种基金Project of Science and Technology R&D Program of China Railway(2016G002-K)R&D Fund Project of China Railway Major Bridge Reconnaissance&Design Institute Co.,Ltd.(2021)R&D Fund Project of China Railway Shanghai Group(2021141).
文摘Purpose–The bridge expansion joint(BEJ)is a key device for accommodating spatial displacement at the beam end,and for providing vertical support for running trains passing over the gap between the main bridge and the approach bridge.For long-span railway bridges,it must also be coordinated with rail expansion joint(REJ),which is necessary to accommodate the expansion and contraction of,and reducing longitudinal stress in,the rails.The main aim of this study is to present analysis of recent developments in the research and application of BEJs in high-speed railway(HSR)long-span bridges in China,and to propose a performance-based integral design method for BEJs used with REJs,from both theoretical and engineering perspectives.Design/methodology/approach–The study first presents a summary on the application and maintenance of BEJs in HSR long-span bridges in China representing an overview of their state of development.Results of a survey of typical BEJ faults were analyzed,and field testing was conducted on a railway cable-stayed bridge in order to obtain information on the major mechanical characteristics of its BEJ under train load.Based on the above,a performance-based integral design method for BEJs with maximum expansion range 1600 mm(±800 mm),was proposed,covering all stages from overall conceptual design to consideration of detailed structural design issues.The performance of the novel BEJ design thus derived was then verified via theoretical analysis under different scenarios,full-scale model testing,and field testing and commissioning.Findings–Two major types of BEJs,deck-type and through-type,are used in HSR long-span bridges in China.Typical BEJ faults were found to mainly include skewness of steel sleepers at the bridge gap,abnormally large longitudinal frictional resistance,and flexural deformation of the scissor mechanisms.These faults influence BEJ functioning,and thus adversely affect track quality and train running performance at the beam end.Due to their simple and integral structure,deck-type BEJs with expansion range 1200 mm(±600 mm)or less have been favored as a solution offering improved operational conditions,and have emerged as a standard design.However,when the expansion range exceeds the above-mentioned value,special design work becomes necessary.Therefore,based on engineering practice,a performance-based integral design method for BEJs used with REJs was proposed,taking into account four major categories of performance requirements,i.e.,mechanical characteristics,train running quality,durability and insulation performance.Overall BEJ design must mainly consider component strength and the overall stiffness of BEJ;the latter factor in particular has a decisive influence on train running performance at the beam end.Detailed BEJ structural design must stress minimization of the frictional resistance of its sliding surface.The static and dynamic performance of the newlydesigned BEJ with expansion range 1600 mm have been confirmed to be satisfactory,via numerical simulation,full-scale model testing,and field testing and commissioning.Originality/value–This research provides a broad overview of the status of BEJs with large expansion range in HSR long-span bridges in China,along with novel insights into their design.
基金Project(2009BAG15B03) supported by the National Science and Technology Ministry of ChinaProjects(51178100, 51078080) supported by the National Natural Science Foundation of China+1 种基金Project(BK2011141) supported by the Natural Science Foundation of Jiangsu Province, ChinaProject(12KB02) supported by the Open Fund of the Key Laboratory for Safety Control of Bridge Engineering(Changsha University of Science and Technology), Ministry of Education, China
文摘Damage alarming and safety evaluation using long-term monitoring data is an area of significant research activity for long-span bridges. In order to extend the research in this field, the damage alarming technique for bridge expansion joints based on long-term monitoring data was developed. The effects of environmental factors on the expansion joint displacement were analyzed. Multiple linear regression models were obtained to describe the correlation between displacements and the dominant environmental factors. The damage alarming index was defined based on the multiple regression models. At last, the X-bar control chart was utilized to detect the abnormal change of the displacements. Analysis results reveal that temperature and traffic condition are the dominant environmental factors to influence the displacement. When the confidence level of X-bar control chart is set to be 0.003, the false-positive indications of damage can be avoided. The damage sensitivity analysis shows that the proper X-bar control chart can detect 0.1 cm damage-induced change of the expansion joint displacement. It is reasonably believed that the proposed technique is robust against false-positive indication of damage and suitable to alarm the possible future damage of the expansion joints.
文摘The expansion joints are expected to have movement capacity, bearing capacity for static and dynamic loading, water-tightness, low noise emission and traffic safety. In particular, the failure due to impact loading is the main reason for the observed damages. The problem of dynamic behavior of the expansion joints is so complex that we shall focus our attention on the impact factor for vehicle load that is governed by traffic impact. In order to overcome this difficulty, the cantilever-toothed aluminum joint (finger joint) is one of the promising joints under impact loading. In this study, from the viewpoint of design methodology, numerical studies for impact behavior were conducted for aluminum alloy expansion joints with perforated dowels. The design impact factor for the expansion joints with the perforated dowels against traffic impact loading was examined by using numerical simulations.
基金Funded by National Natural Science Foundation of China(Nos.51578545,51378499 and 51708557)Technological Research and Development Programs of China Railways Corporation(Nos.2008G031-N,2013G008-A-3)Technological Research and Development Programs of China Academy of Railways Sciences(Nos.2012YJ025,2016YJ047)
文摘Expansion joints silicone sealants used in high speed railway construction suffer from ultraviolet radiation（UV）, high temperature combined with the alkaline environment. To evaluate the durability and analyse the ageing mechanism, six one-component silicone sealants from different companies were selected and subjected to accelerated ageing tests including UV, thermal and alkali ageing treatments. The ageing effects on the performance of the sealants were evaluated via the appearance and the mechanical property changes. The changes in molecular structure were studied by means of Fourier transform infrared spectroscopy（FTIR）, differential scanning calorimetry（DSC） and thermogravimetry（TG）. This study revealed that different materials displayed different sensibilities to the ageing methods, in which 15 %-20 % decreases of mechanical properties could be observed under UV radiation test, owning the most significant effects. Structure analysis showed that the physical changes of aggregative states were the principal factors to the performance, along with the chemical slight changes. The glossiness dropped significantly in ageing test, which could be used as one of the effective evaluation parameters for ageing conditions in the field.
基金This work was supported by the Guangdong Innovative and Entrepreneurial Research Team Program(No.2016ZT06G025)Guangdong Natural Science Foundation(NO: 2017B030306014).
文摘The influence of expansion joints on the welding residual stress at the tube-plate junction of an exhaust gas recirculation(EGR)cooler was studied by numerical simulation method.The simulation results show that the expansion joints set on the housing of the EGR cooler mainly for the sake of protecting the tube-plate joints from bearing additional heating stress can also reduce the welding residual tensile stress.The expansion joints set on the EGR cooler can mitigate the tensile force acting on the edges of the main plates through its elastic extension,and thus reduce the magnitude of welding residual tensile stress at the tube-plate junction.
文摘In design phases, expansion joints are required to have movement capacity, bearing capacity for static and dynamic loading, watertight, low noise emission and traffic safety. On the basis of the fact that failure due to dynamic loading is the main reason for the observed damages, attention is focused on the bearing capacity for dynamic loading governed by impact, because it differs from the static loading. In this study, from the viewpoint of durability, experimental studies for dynamic behavior were conducted for aluminium alloy expansion joints with perforated dowels. The validity of the perforated dowels against traffic impact loading was confirmed by both experimental and numerical studies.
文摘The article summarizes related research results and achievements of elastomer expansion device in railway bridge and puts forward a new idea of using polyurethane elastomer material to seal concrete bridge joints between adjacent spans in heavy haul railways. The new type expansion device is composed of polyurethane elastomer material and named TTXF （elastomer expansion joint）. In theory, researchers find out expansion joint deformation regularity between adjacent bridge spans through theoretical analysis and detection in heavy haul railways, such as Datong-Qinhuangdao Railway and Shenchi-Huanghua Port Railway. Fatigue tests prove that TTXF can adapt to permanent and dynamic deformation. On the other hand, it has been successfully applied in the test section of Central South of Shanxi Railway Passage and continuous monitoring has been conducted in extreme weather for over one year. The expansion joint has a good effect practically.
基金supported by the National Major Science and Technology Project“Optimal and fast ultra-deep HTHP well construction and gas recovery technologies”(No.:2016ZX05051003)the National Natural Science Foundation of China(General Program)“Theoretical and experimental studies on key mechanical aspects in unconventional gas recovery”(No.:11272216).
文摘In Well MJ4,Tarim Basin,the testing tubing string is 6617 m long and the bottom-hole pressure during the testing is 101.63 MPa.During the completion job,plastic deformation occurs in the tubing string,so it is very necessary to figure out at which stage of the completion job plastic deformation occurs on earth.For this reason,the three-dimension finite element analysis method was used to perform numerical calculations for the deformation of tubing string and the distribution of axial stress based on three typical load conditions(setting load,fracturing load,and well testing load of Well MJ4);a process for calculating the mechanical behavior of a completion and testing tubing string containing an expansion joint was then developed.The study content mainly includes:(1)A criterion was developed to determine the extension and closure status of the expansion joint in the tubing string;corresponding calculation mechanism and formulae were provided;and the extensioneclosure status of the expansion joint in the tubing string for Well MJ4 was calculated.(2)A method was developed for analyzing and calculating the additional pressure difference load in the packer annulus caused by poor engagement of the hydraulic anchor;the impact of the additional pressure difference load on the deformation behavior of the tubing string was simulated;and the significant impact of the additional pressure difference load on the plastic buckling deformation was figured out.(3)The limit of lateral buckling deformation in a calculation model was introduced,and so the impact of collar rigidity on the buckling deformation was indirectly considered;the deformation under the joint action of all loads of the tubing string was calculated,and the numerical result was the same as the observed deformation.The study results show that the plastic deformation of the tubing string for Well MJ4 occurs at the fracturing stage and the major causes are hydraulic pressure loads and gravity loads in different forms.The conclusion shows that the mechanical calculation model of the testing tubing containing the expansion joint can be used as an important theoretical tool and analysis approach in optimizing operations and designing the tubing string structure.
文摘Expansion joint construction is an important part of road and bridge engineering. Good construction quality control of this link plays an important role in improving the construction quality of the whole project. Expansion joint construction technology is not closed, not only will affect the whole project, there will be a lot of fatal security risks. In road and bridge construction, expansion joint construction technology is related to bridge deformation. Reasonable research on construction technology of road and bridge expansion joints can not only avoid cracks, but also fundamentally improve the reliability and safety of road and bridge engineering. Next, the article discusses the expansion joint construction technology in road and bridge engineering.
基金the support of the National Natural Science Foundation of China(Grant Nos.50725828,50808041 and 50978056)the Ph.D.Program Foundation of the Ministry of Education of China(Grant No.200802861011)the Teaching and Research Foundation for Excellent Young Teachers of Southeast University.
文摘This paper addresses the problem of condition assessment of bridge expansion joints using long-term measurement data under changing environmental conditions.The effects of temperature,traffic loading and wind on the expansion joint displacements are analyzed and interpreted,which reveal that measured displacements are observed to increase with an increase in temperature and to decrease with increased traffic loading,while the correlation between displacement and wind speed is very weak.Two regression models are developed to simulate the varying displacements under the changes in temperature and traffic loadings.Based on these models,the effects of the environmental conditions are removed to obtain the normalized displacement.Statistical process control using mean value control charts is further used to detect damage to the bridge expansion joints.The results reveal that the proposed method had a good capability for detecting the damage-induced 1.0%variances of the annual changes in the expansion joint displacements.
文摘BASF and Sinopec began the construction for the expansion of their joint venture,BASF-YPC Co.,Ltd. (BYC). BASF and Sinopec plan to jointly invest approximately $1.4 billion
基金supported by the National Key R&D Program of China(2022YFB2602901)the National Natural Science Foundation of China(No.52178405).
文摘The complex bridge-track interaction between kilometer-span bridges and continuous Welded Rail(CWR)brings great challenges to CWR designing.Taking a suspension bridge with laying CWR as a case,the mechanical properties of CWR on the bridge are analyzed to reveal the sensitive areas of the track,and the design method of CWR and track structures on the beam ends are proposed.The results show that the unidirectional Rail Expansion Joints(REJ)need to be installed on the beam end of the kilometer-span bridge to reduce rail longitudinal force.Due to the bridge characteristics,there is no CWR fixed area on the kilometer-span bridge,and rail longitudinal force on the main span caused by bending loads needs to be concerned.The deformation of track on the beam end is complex,which is the weak area on the kilometer bridge,the large relative displacement between the stock rail of REJ and the main beam can cause poor stability of ballast bed on beam end,small resistance fasteners need to be laid on the sides of stock rail on the main beam to increase the stability of ballast and fasteners on the beam end.To improve the driving safety and comfort of beam end,the Sleeper-Supporting Apparatus(SSA)should be specially designed to ensure the uniform transition of track on beam ends.Temperature and wind loads have a significant impact on track regularity on the kilometer span bridge,the dynamic response of trains and bridges under those loads needs to be attended to.
基金This work was supported by the National Natural Science Foundation of China(Nos.41901073 and 52078435)the Sichuan Science and Technology Program(No.2021YJ0001)。
文摘Stress concentration occurs in the foundations of railway tracks where discontinuous components are located.The exacerbated stress under the expansion joints in slab tracks may trigger foundation failures such as mud pumping.Although the higher stress due to the discontinuities of track structures has been discussed in past studies,few focused on the stress response of roadbeds in slab tracks and quantitatively characterized the stress pattern.In this paper,we performed a dynamic finite element analysis of a track-formation system,incorporating expansion joints as primary longitudinal discontinuities.The configurations of CRTS Ⅲ slab tracks and the contact conditions between concrete layers were considered.Numerical results show that longitudinal influencing length of induced stress on roadbed under wheel load relates to the contact conditions between concrete layers,increasing nonlinearly at a larger coefficient of friction.Given a measured coefficient of friction of 0.7,the calculated longitudinal influencing length(9.0 m) matches with field data.The longitudinal influencing length is not affected with the increasing velocity.As stress concentration arises with expansion joints,the worstcase scenario emerges when double-axle loads are exerted immediately above the expansion joints between concrete bases.A stress concentration factor Cvon the roadbed is proposed;it increases with the increasing velocity,changing from 1.33 to 1.52 at velocities between 5 and 400 km/h.The stress distribution on roadbeds transforms from a trapezoid pattern at continuous sections to a triangle pattern at points with longitudinal discontinuities.An explicit expression is finally proposed for the stress pattern on roadbed under expansion joints.Although structural discontinuities induce stress raiser,the extent of concentration is mitigated with increasing depth at different velocity levels.
基金This paper was financially supported by the National Natural Science Foundation of China(52038001,52122809).
文摘With the continuous development of bridge and tunnel construction technologies,large-scale sea-crossing bridges and tunnels have gradually become the preferred choice for regional traffic.The construction technology of Hong Kong-Zhuhai-Macao Bridge(HZMB),one of the most representative sea-crossing passageways,is instructive for the construction of other large sea-crossing infrastructures.At present,the pavement design method of sea-crossing passageways lacks pertinence as it still refers to specifications for design of common pavement.Therefore,it is necessary to consider the bridge and tunnel pavement of HZMB as a typical example to analyze key technical problems encountered in its design,construction and operation.Novel solutions for material selection and structural design built upon the analysis of such critical problems should thus follow up.Based on comprehensive literature research,it can be found that environmental variability,tunnel closure,structural differential settlement and expansion deformation are the key technical problems faced by pavement of sea-crossing passageways.In view of the environmental variability,the steel deck-paving material and structure design of GMA-10 t SMA-13 is innovatively proposed.As for the closure of immersed tube tunnel,warm-mix flame retardant asphalt mixture is used to control pavement design through key indexes such as temperature and limit oxygen index.Regarding the deformation of immersed pipe joints,BJ200 asphalt seamless expansion joint material is introduced,which effectively satisfies the multi-directional deformation between pipe joints and ensures the smoothness of the road surface and driving comfort.For segmental joints,double-layer waterproof-coiled material is used to effectively prevent reflective cracks while ensuring the continuity of asphalt concrete pavement.Therefore,this paper provides a panel of ideas and methods for the pavement design of the same type of sea-crossing passageways.
文摘In ITER facilities, there are some special expansion joints connected with the openings of cryostat. Expect for the assemblies connected with NB openings, others are rectangular section with big dimensions and severe working conditions and they are important for ITER safe runing.
基金This research was supported by the National Natural Science Foundation of China(Grant Nos.51908015,51978021)National Key Research and Development Program of China(Grant Nos.2017YFC1500604,2017YFC1500603)+1 种基金Beijing Municipal Education Commission(Nos.KM201910005020,IDHT20190504)the Basic Research Fund of Beijing University of Technology(No.004000546318524).
文摘A long-span concrete-filled steel tubular(CFST)arch bridge suffers severe vehicle-induced dynamic responses during its service life.However,few quantitative studies have been reported on the typical diseases suffered by such bridges and their effects on vehicle-induced dynamic response.Thus,a series of field tests and theoretical analyses were conducted to study the effects of typical diseases on the vehicle-induced dynamic response of a typical CFST arch bridge.The results show that a support void results in a height difference between both sides of the expansion joint,thus increasing the effect of vehicle impact on the main girder and suspenders.The impact factor of the displacement response of the main girder exceeds the design value.The variation of the suspender force is significant,and the diseases are found to have a greater effect on a shorter suspender.The theoretical analysis results also show that the support void causes an obvious longitudinal displacement of the main girder that is almost as large as the vertical displacement.The support void can also cause significant changes in the vehicle-induced acceleration response,particularly when the supports and steel box girder continue to collide with each other under the vehicle load.
文摘This study describes a developing process of lifeline earthquake engineering from historical aspects.Currently various seismic design methods have been furnished for ground shaking and for permanent ground displacement.The seismic design method for ground shaking introduces different travelling wave models in the US and in Japan.As a result,Japanese approach was developed by actively taking into account the slippage effect in order to solve the inelastic response of the pipeline for a severe earthquake.The seismic design method for permanent ground displacement,on the other hand,prepared various numerical modeling and database in the US,while the simplified design formula for ground displacement was furnished in the seismic design guidelines in Japan.The detail design formula for liquefied ground settlement and fault displacement are expressed in this study.Various approaches of the performance-based seismic design method are compared among EU,the US and Japan.Unfortunately,the design method in Japan does not show the safety target in the guidelines.Then a simple evaluation approach to obtain the safety index is proposed herein.The different performance of two actual pipeline systems is compared,in which one pipeline system demonstrated a good performance for 2011 East Japan Great Earthquake,and the other did not.In state-of-the-art study,the seismic experiments and design method of expansion joints are described,because the ultimate limit performance of the expansion joints has not been explicit,although many seismic damages have occurred at the locations of vulnerable expansion joints.
