The hangers of suspension bridges can be placed in two forms: vertical or inclined form. Inclined hangers are more liable to fatigue. Vertical hangers are subjected to greater fluctuations of stress resulting from bri...The hangers of suspension bridges can be placed in two forms: vertical or inclined form. Inclined hangers are more liable to fatigue. Vertical hangers are subjected to greater fluctuations of stress resulting from bridge wind loads. To improve aerodynamic stability, inclined hangers can be used instead of vertical ones. Some inclined hangers show considerable signs of distress and some of them show slackness due to their location against loads. In this paper a pedestrian suspension bridge with vertical hangers has been studied as a case study. Then, the same bridge has been studied with inclined hangers. To reduce internal forces, fatigue and slackness in hangers, horizontal cables have been added to inclined hangers. This modification is proposed by the present authors. The added horizontal cables transfer the tensile load from overstressed hangers to adjacent slacked hangers. Three different hanger patterns have been analyzed under nonlinear static analysis for symmetrical and nonsymmetrical live load plus dead load. Results showed that the modified hanger system had been improved considerably in comparison with vertical or inclined hangers and wherever that there is no improvement some solutions have been proposed.展开更多
The use of Network hanger arrangement, a development of the classical Nielsen V-hanger system, in steel bowstring arch bridges allows for important steel saving, with very slender main elements, owing to the remarkabl...The use of Network hanger arrangement, a development of the classical Nielsen V-hanger system, in steel bowstring arch bridges allows for important steel saving, with very slender main elements, owing to the remarkable reduction of bending stresses in the arches and tie beams. The present paper describes the main features of the design and construction of several long-span arch bridges of this typology in Spain： the three pedestrian footbridges for the Madrid cycling ring track, with spans of 52, 60 and 80 m, the Bridge over River Deba in Guipuzcoa with a span of 110 m and Palma del Rio Bridge over River Guadalquivir in Cordoba, 130 m long. In all cases, two inclined arches linked at the crown were implemented, a very effective disposition to reduce the out-of-plane buckling length. The multiple crossings of the hanger system, consisting of prestressed bars in the case of Deba Bridge and the footbridges, and locked coil cables for Palma del Rio Bridge, were dealt with by means of crossing devices which led to a technically satisfactory solution with minimal visual impact. An innovative approach to bowstring arches was introduced in Valdebebas Bridge over M-12 motorway in Madrid, next to the new T-4 Terminal of Barajas Airport, with a span of 162 m, where the hangers are replaced by a structural steel mesh -diagrid- which acts as the web of a simply-supported beam whose compression head is the arch and the tie beam is the deck.展开更多
The back of the mirror is mainly decorated with dragon patterns,in which the head of the dragon is perking up.and the body of the dragon stretches freely.This is the largest ancient copper mirror ever seen.The bronze ...The back of the mirror is mainly decorated with dragon patterns,in which the head of the dragon is perking up.and the body of the dragon stretches freely.This is the largest ancient copper mirror ever seen.The bronze mirror is used to reflect the human image.SO the surface must be bright and fiat.For sucha casting with a large flat surface,it is extremely difficult to control the mirror surface without warpingdeformation.展开更多
This article discussed how to improve constant force performance of the large capacity constant spring support hangers. Large deviations have been found between product testing results and theoretical calculations aft...This article discussed how to improve constant force performance of the large capacity constant spring support hangers. Large deviations have been found between product testing results and theoretical calculations after years of research and testing. The deviations mainly are caused by internal frictions inside the constant spring support hangers. By reducing or properly using internal frictions, consistent results between testing and theoretical calculation have been achieved. Based on product performance testing results recently, constant force performance of hangers has been improved greatly by adopting new methodology.展开更多
The tubing hanger is an important component of the subsea Christmas tree, experiencing big temperature difference which will lead to very high thermal stresses. On the basis of API 17D/ISO 13628-4 and ASME VIII-1, and...The tubing hanger is an important component of the subsea Christmas tree, experiencing big temperature difference which will lead to very high thermal stresses. On the basis of API 17D/ISO 13628-4 and ASME VIII-1, and by comprehensively considering the erosion of oil and the gravity load of the tubing, a calculation model is established by regarding design pressure and thermal stress, and the method for designing the tubing hanger of the horizontal Christmas tree under big temperature difference condition is developed from the fourth strength theory. The proposed theory for strength design of the tubing hanger in big temperature difference is verified by numerical results from ABAQUS.展开更多
In order to solve the problem of data island in the safety management ofoffshore oil and gas fields, take full advantage of data for subsequent analysis anddevelopment, and support production safety management of oil ...In order to solve the problem of data island in the safety management ofoffshore oil and gas fields, take full advantage of data for subsequent analysis anddevelopment, and support production safety management of oil and gas fields, the MES,which is maturely applied in manufacturing and downstream production of CNOOC(China National Offshore Oil Corporation), is introduced by the petroleum administrationat the eastern South China sea. The system adopts the real-time database and relationaldatabase to collect the scattered structured data, such as evidence information of offshoreoil and gas production facilities personnel, on-site hidden danger information andincident investigation report. Then a unified secure data center platform is established forevery operating area and production site, and the critical safety data of production sitescan be centrally managed. This system has the functions of lawful real-time supervisionof personnel qualification, online supervision and trend analysis of hidden dangers, andcentralized management and sharing of incident investigation report. By applying theMES system in security management, the process of safety service becomes standardizedand modularized, the management process becomes normalized, and the efficiency andeffect of overall management is improved.展开更多
A three - dimenslonal finite element model is developed to deal with the polymeric liquid flow in coat - hanger die. This model is used to predict the flow behavior of the 2％ CMC/watsr solution in the coat - hanger d...A three - dimenslonal finite element model is developed to deal with the polymeric liquid flow in coat - hanger die. This model is used to predict the flow behavior of the 2％ CMC/watsr solution in the coat - hanger die with linearly taper manifolds and its validity is experimentally verified quantitatively and qualitatively by using Laser Doppler Velocimetry and Particle Image Velocimetry respectively.展开更多
Recently,inverted T-beams have been used in reinforced concrete(RC)bridges to support transverse precast stringers.Inverted T-beams,contrary to practice with conventional beams,are loaded on the flanges upper surface....Recently,inverted T-beams have been used in reinforced concrete(RC)bridges to support transverse precast stringers.Inverted T-beams,contrary to practice with conventional beams,are loaded on the flanges upper surface.This loading configuration causes hanger failure due to the generation of vertical tensile stresses near the bottom of the web.The key purpose of this study is to investigate the efficiency of vertical external prestressing stainless-steel bars in mitigating non-ductile hanger failure in reinforced concrete inverted T-beams.An experimental study on six inverted-T beams,including two un-strengthened specimens,was carried out.The study showed that the value of the prestressing level had a considerable impact on the performance of hanger mechanism in relation to crack pattern,ultimate loads,cracking behavior,load-deflection,strains,and ductility.The experimental results indicated that the suggested method for strengthening inverted T-beams had efficacy in reducing the seriousness of the non-ductile hanger failure and resulted in a strength increase of up to 53% when compared to that of the un-strengthened specimen.Additionally,two analytical models for estimating the hanger capacity and the average crack width of the strengthened RC inverted T-beams were proposed.The models that were proposed exhibited a high degree of agreement with the experimental results.展开更多
文摘The hangers of suspension bridges can be placed in two forms: vertical or inclined form. Inclined hangers are more liable to fatigue. Vertical hangers are subjected to greater fluctuations of stress resulting from bridge wind loads. To improve aerodynamic stability, inclined hangers can be used instead of vertical ones. Some inclined hangers show considerable signs of distress and some of them show slackness due to their location against loads. In this paper a pedestrian suspension bridge with vertical hangers has been studied as a case study. Then, the same bridge has been studied with inclined hangers. To reduce internal forces, fatigue and slackness in hangers, horizontal cables have been added to inclined hangers. This modification is proposed by the present authors. The added horizontal cables transfer the tensile load from overstressed hangers to adjacent slacked hangers. Three different hanger patterns have been analyzed under nonlinear static analysis for symmetrical and nonsymmetrical live load plus dead load. Results showed that the modified hanger system had been improved considerably in comparison with vertical or inclined hangers and wherever that there is no improvement some solutions have been proposed.
文摘The use of Network hanger arrangement, a development of the classical Nielsen V-hanger system, in steel bowstring arch bridges allows for important steel saving, with very slender main elements, owing to the remarkable reduction of bending stresses in the arches and tie beams. The present paper describes the main features of the design and construction of several long-span arch bridges of this typology in Spain： the three pedestrian footbridges for the Madrid cycling ring track, with spans of 52, 60 and 80 m, the Bridge over River Deba in Guipuzcoa with a span of 110 m and Palma del Rio Bridge over River Guadalquivir in Cordoba, 130 m long. In all cases, two inclined arches linked at the crown were implemented, a very effective disposition to reduce the out-of-plane buckling length. The multiple crossings of the hanger system, consisting of prestressed bars in the case of Deba Bridge and the footbridges, and locked coil cables for Palma del Rio Bridge, were dealt with by means of crossing devices which led to a technically satisfactory solution with minimal visual impact. An innovative approach to bowstring arches was introduced in Valdebebas Bridge over M-12 motorway in Madrid, next to the new T-4 Terminal of Barajas Airport, with a span of 162 m, where the hangers are replaced by a structural steel mesh -diagrid- which acts as the web of a simply-supported beam whose compression head is the arch and the tie beam is the deck.
文摘The back of the mirror is mainly decorated with dragon patterns,in which the head of the dragon is perking up.and the body of the dragon stretches freely.This is the largest ancient copper mirror ever seen.The bronze mirror is used to reflect the human image.SO the surface must be bright and fiat.For sucha casting with a large flat surface,it is extremely difficult to control the mirror surface without warpingdeformation.
文摘This article discussed how to improve constant force performance of the large capacity constant spring support hangers. Large deviations have been found between product testing results and theoretical calculations after years of research and testing. The deviations mainly are caused by internal frictions inside the constant spring support hangers. By reducing or properly using internal frictions, consistent results between testing and theoretical calculation have been achieved. Based on product performance testing results recently, constant force performance of hangers has been improved greatly by adopting new methodology.
基金financially supported by the National Science and Technology Major Project of China(Grant No.2011ZX05026-003-02)the National High Technology Research and Development Program of China(863 Program,Grant No.2012AA09A205)
文摘The tubing hanger is an important component of the subsea Christmas tree, experiencing big temperature difference which will lead to very high thermal stresses. On the basis of API 17D/ISO 13628-4 and ASME VIII-1, and by comprehensively considering the erosion of oil and the gravity load of the tubing, a calculation model is established by regarding design pressure and thermal stress, and the method for designing the tubing hanger of the horizontal Christmas tree under big temperature difference condition is developed from the fourth strength theory. The proposed theory for strength design of the tubing hanger in big temperature difference is verified by numerical results from ABAQUS.
文摘In order to solve the problem of data island in the safety management ofoffshore oil and gas fields, take full advantage of data for subsequent analysis anddevelopment, and support production safety management of oil and gas fields, the MES,which is maturely applied in manufacturing and downstream production of CNOOC(China National Offshore Oil Corporation), is introduced by the petroleum administrationat the eastern South China sea. The system adopts the real-time database and relationaldatabase to collect the scattered structured data, such as evidence information of offshoreoil and gas production facilities personnel, on-site hidden danger information andincident investigation report. Then a unified secure data center platform is established forevery operating area and production site, and the critical safety data of production sitescan be centrally managed. This system has the functions of lawful real-time supervisionof personnel qualification, online supervision and trend analysis of hidden dangers, andcentralized management and sharing of incident investigation report. By applying theMES system in security management, the process of safety service becomes standardizedand modularized, the management process becomes normalized, and the efficiency andeffect of overall management is improved.
文摘A three - dimenslonal finite element model is developed to deal with the polymeric liquid flow in coat - hanger die. This model is used to predict the flow behavior of the 2％ CMC/watsr solution in the coat - hanger die with linearly taper manifolds and its validity is experimentally verified quantitatively and qualitatively by using Laser Doppler Velocimetry and Particle Image Velocimetry respectively.
文摘Recently,inverted T-beams have been used in reinforced concrete(RC)bridges to support transverse precast stringers.Inverted T-beams,contrary to practice with conventional beams,are loaded on the flanges upper surface.This loading configuration causes hanger failure due to the generation of vertical tensile stresses near the bottom of the web.The key purpose of this study is to investigate the efficiency of vertical external prestressing stainless-steel bars in mitigating non-ductile hanger failure in reinforced concrete inverted T-beams.An experimental study on six inverted-T beams,including two un-strengthened specimens,was carried out.The study showed that the value of the prestressing level had a considerable impact on the performance of hanger mechanism in relation to crack pattern,ultimate loads,cracking behavior,load-deflection,strains,and ductility.The experimental results indicated that the suggested method for strengthening inverted T-beams had efficacy in reducing the seriousness of the non-ductile hanger failure and resulted in a strength increase of up to 53% when compared to that of the un-strengthened specimen.Additionally,two analytical models for estimating the hanger capacity and the average crack width of the strengthened RC inverted T-beams were proposed.The models that were proposed exhibited a high degree of agreement with the experimental results.
