| As a new type of large-scale aqueduct structure,the large-span continuous rigidstructure aqueduct has been applied in more and more places.Because the aqueduct's web acts as a water passage,the web must be protected from cracking during the entire life cycle,but the large-span continuous rigid-structure tank container will be subjected to the heat of formation,web heat,and cantilever during construction and completion of the bridge.During the construction process,the shrinkage and creep of concrete,the overall temperature of the whole structure during the completion phase of the bridge,the temperature gradient,the water load,and the vertical prestress in the web,etc.,are too complex to take into consideration in consideration of various loads and are not conducive to the designer.Because of the design of vertical prestressing,this paper will use the Xujiawan continuous rigid-structure aqueduct of the Jizhong water conservancy project as its research background to conduct the following researches:(1)A design method based on stress superposition of the entire life cycle of the web will be proposed to design the vertical prestress at the web.That is,firstly,the influence of each load on the web of the box girder of the aqueduct is analyzed separately and calculated by stress superposition.The pre-stress of the concrete needed for the most unfavorable position of the web will guide the study of the design of the vertical prestressed tendon arrangement for the super-high web near the pier.(2)The influencing factors of the force of the web of long-span continuous rigidstructure aqueducts will be combed,mainly including the hydration heat of the continuous rigid-structure aqueduct web formation process,the superimposed stress produced by the cantilever construction scheme of the long-span continuous rigid frame,and the bridge formation,Long-term shrinkage and creep during operation,temperature loads during bridge formation,and vertical prestressing at thick webs.(3)Taking the Xujiawan continuous rigid-frame aqueduct as an example,the finite element solid model of the continuous rigid-structure aqueduct will be established by using the Midas/FEA finite element software.The detailed analysis will be conducted according to the factors affecting the web force of the long-span continuous rigidstructure aqueduct.The influence of the heat of hydration during the web formation process and the cumulative stress during the construction of the cantilever on the stress of the web will be investigated.The influence of different environmental humidity on the ten-year contraction and creep stress of the continuous rigid-structure aqueduct web will be further discussed.(4)In-depth analysis of external environment temperature changes and different temperatures in the inner and outer environment of the web to the web of large-span continuous rigid frame aqueduct from the overall elevation of the aqueduct structure,the temperature difference between the inside and outside of the web,and the temperature difference between the inside of the upper chamber and the outside of the upper chamber affected by the force.(5)This paper will discuss the impact on the web of large-span continuous rigidstructure aqueducts through the heat of hydration during web formation,cumulative stress during cantilever construction,shrinkage and creep during long-term operation during bridge formation,and temperature load during the operational phase of bridge formation.The analysis of the load will be based on the calculation method on the stress superposition of the web throughout its life cycle for the vertical prestressed steel beam design at the ultrahigh web near the high pier.In consideration of the prestress loss and shrinkage creep,the effectiveness of the scheme will be verified,which provide a reference basis for the vertical apron to improve the stress of the web. |
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