To analyze the dynamic response and reliability of a continuous beam bridge under the action of an extra heavy vehicle, a vehicle–bridge coupled vibration model was established based on the virtual work principle and...To analyze the dynamic response and reliability of a continuous beam bridge under the action of an extra heavy vehicle, a vehicle–bridge coupled vibration model was established based on the virtual work principle and vehicle–bridge displacement compatibility equation, which can accurately simulate the dynamic characteristics of the vehicle and bridge. Results show that deck roughness has an important function in the effect of the vehicle on the bridge. When an extra heavy vehicle passes through the continuous beam bridge at a low speed of 5 km/h, the impact coefficient reaches a high value, which should not be disregarded in bridge safety assessments. Considering that no specific law exists between the impact coefficient and vehicle speed, vehicle speed should not be unduly limited and deck roughness repairing should be paid considerable attention. Deck roughness has a significant influence on the reliability index, which decreases as deck roughness increases. For the continuous beam bridge in this work, the reliability index of each control section is greater than the minimum reliability index. No reinforcement measures are required for over-sized transport.展开更多
Sutong Bridge is a cable-stayed bridge with a steel box girder and a main span of 1 088 m.The steel box girder of main span includes five portions:back span large unit,large block of pylon,standard girder,back span cl...Sutong Bridge is a cable-stayed bridge with a steel box girder and a main span of 1 088 m.The steel box girder of main span includes five portions:back span large unit,large block of pylon,standard girder,back span closure girder and middle span closure girder.Each back span large unit is fabricated by welding several deck segments together in factory,and is erected by floating crane.As navigational clearance of the main bridge is high,the traditional truss lifting device can't satisfy the requirement of domestic lifting cranes for this kind of lifting height and weight.Hence,a kind of lighter lifting device for the erection of back span large units was accepted for this bridge.In this paper,the design and use of this lifting device is introduced.The upper structure used lifting gantry to install the standard girder segment by cantilever method.Because the bridge's navigation clearance is high,and the girder segment is wide and heavy,the meteorology and hydrology condition of the bridge district is abominable,and the requirements of long cable girder side pull-in,structure and performance propose high request to the lifting gantry.In this paper,the design and use key point of long cable pull-in angle adjustment device integrate into lifting gantry is introduced.展开更多
It＇ s a necessary selection to support the maneuver across Yangtze River by floating bridge constructed by portable steel bridge and civilian ships. It is a comprehensive index for the scheme of bridge raft, containi...It＇ s a necessary selection to support the maneuver across Yangtze River by floating bridge constructed by portable steel bridge and civilian ships. It is a comprehensive index for the scheme of bridge raft, containing a variety of technical factors and uncertainties. The optimization is the selection in the constructing time, quantity of equipments and man power. Based on the calculation result of bridge rafts, an evaluating system is established, consisting of index of spacing between interior bays, raft length, truss numbers, operation difficulty and maximal bending stress. A fuzzy matter element model of optimizing selection of bridge rafts was built up by combining quantitative analysis with qualitative analysis. The method of combination weighting was used to calculate the value of weights index to reduce the subjective randomness. The sequence of schemes and the optimization resuh were gained finally based on euclid approach degree. The application result shows that it is simple and practical.展开更多
Considering the construction features of prestressed concrete bridge, the comprehensive evaluation method about the bridge damage conditions are studied. Particular attentions are paid on establishing a muhilevel eval...Considering the construction features of prestressed concrete bridge, the comprehensive evaluation method about the bridge damage conditions are studied. Particular attentions are paid on establishing a muhilevel evaluation model for damaged prestressed concrete bridge, and the evaluation indices of the model as well as the rating standards are defined in the model. A normal relative function about the evaluation indices of each element is developed to calculate the relative degree, and for each element which is no sub-level elements. When evaluating the elements in sub-item level or index level of the model, the weights of elements that are pertained to one element are adopted, taking account of their deterioration degree. At the same time, the dam- age conditions of bridge are characterized by relative degree, element evaluation scale and structural technology mark of bridge, so it agrees with Code for Maintenance of Highway Bridges and Culvers.展开更多
基金Project(50779032)supported by the National Natural Science Foundation of ChinaProject(20090451330)supported by the Postdoctoral Foundation of ChinaProject(BS2013SF007)supported by Shandong Scientific Research Award Foundation for Outstanding Young Scientists,China
文摘To analyze the dynamic response and reliability of a continuous beam bridge under the action of an extra heavy vehicle, a vehicle–bridge coupled vibration model was established based on the virtual work principle and vehicle–bridge displacement compatibility equation, which can accurately simulate the dynamic characteristics of the vehicle and bridge. Results show that deck roughness has an important function in the effect of the vehicle on the bridge. When an extra heavy vehicle passes through the continuous beam bridge at a low speed of 5 km/h, the impact coefficient reaches a high value, which should not be disregarded in bridge safety assessments. Considering that no specific law exists between the impact coefficient and vehicle speed, vehicle speed should not be unduly limited and deck roughness repairing should be paid considerable attention. Deck roughness has a significant influence on the reliability index, which decreases as deck roughness increases. For the continuous beam bridge in this work, the reliability index of each control section is greater than the minimum reliability index. No reinforcement measures are required for over-sized transport.
基金National Science and Technology Support Program of China(No.2006BAG04B0)
文摘Sutong Bridge is a cable-stayed bridge with a steel box girder and a main span of 1 088 m.The steel box girder of main span includes five portions:back span large unit,large block of pylon,standard girder,back span closure girder and middle span closure girder.Each back span large unit is fabricated by welding several deck segments together in factory,and is erected by floating crane.As navigational clearance of the main bridge is high,the traditional truss lifting device can't satisfy the requirement of domestic lifting cranes for this kind of lifting height and weight.Hence,a kind of lighter lifting device for the erection of back span large units was accepted for this bridge.In this paper,the design and use of this lifting device is introduced.The upper structure used lifting gantry to install the standard girder segment by cantilever method.Because the bridge's navigation clearance is high,and the girder segment is wide and heavy,the meteorology and hydrology condition of the bridge district is abominable,and the requirements of long cable girder side pull-in,structure and performance propose high request to the lifting gantry.In this paper,the design and use key point of long cable pull-in angle adjustment device integrate into lifting gantry is introduced.
文摘It＇ s a necessary selection to support the maneuver across Yangtze River by floating bridge constructed by portable steel bridge and civilian ships. It is a comprehensive index for the scheme of bridge raft, containing a variety of technical factors and uncertainties. The optimization is the selection in the constructing time, quantity of equipments and man power. Based on the calculation result of bridge rafts, an evaluating system is established, consisting of index of spacing between interior bays, raft length, truss numbers, operation difficulty and maximal bending stress. A fuzzy matter element model of optimizing selection of bridge rafts was built up by combining quantitative analysis with qualitative analysis. The method of combination weighting was used to calculate the value of weights index to reduce the subjective randomness. The sequence of schemes and the optimization resuh were gained finally based on euclid approach degree. The application result shows that it is simple and practical.
基金the Science and Technology Program for West Communication Construction of MOC(Grant No.2005ZB05)
文摘Considering the construction features of prestressed concrete bridge, the comprehensive evaluation method about the bridge damage conditions are studied. Particular attentions are paid on establishing a muhilevel evaluation model for damaged prestressed concrete bridge, and the evaluation indices of the model as well as the rating standards are defined in the model. A normal relative function about the evaluation indices of each element is developed to calculate the relative degree, and for each element which is no sub-level elements. When evaluating the elements in sub-item level or index level of the model, the weights of elements that are pertained to one element are adopted, taking account of their deterioration degree. At the same time, the dam- age conditions of bridge are characterized by relative degree, element evaluation scale and structural technology mark of bridge, so it agrees with Code for Maintenance of Highway Bridges and Culvers.
