Analysis Of Influence Parameters Of Cable-stayed Bridges Under Uninterrupted Traffic Conditions

China is moving from a big bridge country to a strong bridge country.With the rapid growth of the number of bridges,the management of bridges has changed from a newbuilt era to an era in which both construction and maintenance are paid equal attention.Cable-stayed bridges play an important role in many bridge types-more than 400 have been built in China alone.In the long-term operation process,various diseases have appeared in the cable-stayed bridge built in the early stage,which has laid a great potential safety hazard for the structure operation.In order to avoid serious consequences,replacing cables to prolong the service life of cable-stayed bridges is an effective method.In the cable replacement,the usual method is to close the whole bridge to ensure the construction safety to the greatest extent.With the continuous development of transportation,the troubles brought by this kind of protection measure to citizens' travel and smooth traffic become more and more prominent.However,compared with closed traffic,lane load,temperature load,wind load and other factors will have a certain impact on the design,construction and construction control of cable-stayed bridge under uninterrupted traffic conditions.How to complete cable replacement safely,economically and reasonably is an important issue concerned by all sectors of society.In order to solve such problems,the research on cable-stayed bridge in the planned project is completed,and the cable replacement of cable-stayed bridge is attempted to be explored.Based on the cable replacement project of a cable-stayed bridge in Chongqing,this paper studies the cable replacement scheme of the cable-stayed bridge and the influence of different external factors on the cable replacement of the cable-stayed bridge under uninterrupted traffic conditions.The main research contents are as follows:(1)Summarizes the diseases of cable-stayed bridges and cable replacement methods,and studies the influence of cable replacement with different numbers of cables at the same time,and determines the cable replacement scheme under normal circumstances,taking whether the cable pulling force,the vertical displacement of the main girder and the stress on the upper and lower edges of the main girder are reasonable as control conditions.(2)Influence of different factors on cable replacement.Based on the comparative analysis of three traffic organization schemes including closed traffic,closed 4 lanes on the outside and closed 2 lanes on the construction side,the influence of lane load on cable replacement is analyzed,and the cable replacement scheme is adjusted accordingly.Through the comparative analysis of non-temperature effect,temperature difference effect of cable tower beam,vertical temperature gradient effect of main beam and lateral temperature gradient effect of cable tower,the influence of temperature on cable replacement is analyzed.It is determined that the influence is mainly reflected in the influence on the bridge itself and has little correlation with the cable replacement process,but it cannot be ignored in the design and calculation.Through the comparative analysis of no wind load,static wind load along the transverse bridge and static wind load against the transverse bridge,the influence of static wind load along the transverse bridge on cable replacement is analyzed,and it is determined that the influence on cable tension and vertical displacement of main girder is relatively weak,but its influence on stress of main girder is relatively large.This analysis is mainly qualitative analysis and provides reference for future research.(3)The final cable replacement scheme is determined.This scheme includes cable replacement sequence and corresponding traffic organization,in which the cable tension,deformation and stress of the main girder all meet the control conditions,the construction period is relatively short,and the smooth traffic is ensured,which has certain feasibility.