Study On Lateral Effect And Prestress Tensioning Technology Of Wide Box Multi-web Box Girder

Continuous beam bridge and continuous rigid frame bridge are the most commonly used bridge structures in China's large span concrete bridge.However,continuous beam bridge and continuous rigid frame bridge that have been built have many problems,such as web cracking,Midspan deflection.The main reason is that prestressed steel beam prestress loss is too large,resulting in the actual structure of the bridge stress state and design stress state does not match.The prestress loss of the bridge structure is related to the factors such as the shape of the steel beam,the material characteristics,the tension and so on.And also because of the cantilever construction continuous beam bridge and the continuous rigid frame bridge,The compressive capacity of the concrete is different,and the difference of the elasticity of the concrete produced by the different prestressing steel beam is different,and the concrete elastic compression prestress loss caused by the prestressed steel beam is also different.Therefore,If the steel beam tensioning sequence is unreasonable,it will produce a large prestress loss,the structure is unfavorable.In this paper,a continuous rigid frame bridge in Ordos City,Inner Mongolia,is used as the basis for engineering.The finite element software MIDAS / FEA is used to analyze and calculate the structure.The main research is as follows:(1)The development status and future development trend of wide box multi-web box girder bridge and cantilever construction method are expounded.The main problems existing in wide-box multi-web box bridge are studied.The basic theory of stress analysis method,prestressed tensioning process and prestress loss of wide box multi-web box girder is expounded;(2)The finite element model of full-bridge solid-rigid bridge is established by using MIDAS / FEA.In the actual construction process,the embedded stress sensor is used to collect the stress value of the concrete during the prestressing tension;The transverse effect of wide box multi-web box girder is analyzed;(3)The effects of different tensile strands of prestressed steel beams on prestressing loss of prestressed steel beams in cantilever construction of wide box multi-web box girder bridge are analyzed;The optimal tensioning scheme of prestressed steel beam for wide box multi-web box girder bridge in cantilever construction stage is proposed;The stress changes of the concrete box girder during the tensioning process of the optimal tensioning scheme are analyzed and compared with the measured values of the stress;(4)The influence of different pre-stressed steel beam tension on the prestress loss of the steel beam and the mid-span span;The optimal tensioning scheme of prestressed steel beam in the mid-span of wide-box and multi-web box girder bridge is proposed;The stress changes of the concrete during the tensioning process are analyzed.