Study On Completion State Of Long-Span Prestressed Concrete Continuous Girder Bridge

As an important part of civil engineering,bridge structures have the function of crossing obstacles and being traffic passages,which requires its high level of reliability.The most widely used type of bridge—continuous girder bridges have lots of advantages such as small deformation,good structural stiffness,less expansion joints,which provide comfortable driving experience.Although almost all continuous girder bridges are able to meet the requirements in the code at the beginning of design,due to the lack of research on the status of completed bridges,under external environment and complex load types,internal force changes and local deformation may occur,which seriously affect the safety of bridges.In order to make the state indicators of the bridge in the controllable range during operation,it is necessary to design the bridge based on the reasonable completed state from the beginning.It can not only fundamentally improve the common design ideas and methods in the current design work,but also perfect the construction control theory from the perspective of construction control,guide the construction,and then control the construction errors and improve the completion status of the bridge.This thesis introduced the research status of continuous girder bridges at home and abroad,including the characteristics of continuous girder bridge,common diseases in recent years and related theoretical research status.The definition of structure state and the index of bridge state were introduced.The rationality of structure state should not be limited to the completion time,but run through the long-term operation process.The structure state could be measured by reliability.From the point of view of practical application and the form of specification,the design essentials of continuous girder bridges were analyzed and discussed,and the analysis and control of completed state by different design methods were compared;the main influencing factors were analyzed,and it was pointed out that the existing design methods of the important factors should be modified and improved.Finally,taking a real bridge as an example,the influence of each parameter on the completed time and ten-year structural state of the bridge were analyzed,taking self-weight,prestressing load,concrete elastic modulus,concrete material age and environmental humidity as representatives.The analysis results of engineering example showed that the self-weight has a great influence on the state of completed bridge,although the influence decreases slightly with the increase of operation period;the influence of prestressing load on the state of completed bridge increases with the increase of operation time;the influence of elastic modulus of concrete on the state of completed bridge increases obviously with the increase of time,and the influence of concrete material age on the state of completed bridge in the long-term operation process The influence could not be neglected,and the environmental humidity has a great influence on the state of completed bridge,especially the state of completed bridge based on the whole-life-cycle.