The Active Control Of Deflection And Crack Of Prestressed Concrete Continuous Rigid Frame Bridge

Prestressed concrete continuous rigid frame bridge,because of its many advantages,perfect steel beam tension technology and cantilever construction technology,is widely used.However,after the continuous rigid frame bridge is built,some bridges appear the phenomenon of "cross deflection" and "beam crack".with the develop of time,these diseases also continue to occur,and there is no stopping.from above questions,this paper based on Duo Yi Bridge for the analysis.in order to evaluate the influence degree of factors on flex cracking,and for active control of continuous rigid frame bridge deflection cracking provides the basis,this paper analysis the phase of flexural cracking factors on the construction.1,To the domestic and foreign existing continuous rigid frame bridge type and the span arrangement and part of the continuous rigid frame bridge typical beam disease analysis,induction and summary.Based on the existing research ideas,the influencing factors and the relationship between flexural cracking of continuous rigid frame bridge are analyzed.2,Duoyi bridge as an example.Firstly,it analyzes the construction stage,steel beam duct friction loss,concrete loading age,cement super,vertical seam of flex cracking effect.Then focuses on the analysis of "the same construction beam segment" and "different construction beam segment ",steel beam has a tension sequence,due to compression of concrete elastic,and cause the effective force loss,of continuous rigid frame bridges cross the influence of middle and lower deflection and internal force on cross section.And draw a conclusion:(1)Large span prestressed concrete continuous rigid frame bridge,steel beam layout is different from other small and medium span box girder bridge.The steel beam layout is increased with the growth of span,Changgang beam pipe friction loss has not only in accordance with the requirements of the standard value.At the same time,the friction loss of steel beam pipe brought is more and more difficult to estimate.Therefore,this paper suggests that in the continuous rigid frame bridge design and construction stage,are suitable for pipeline steel beam amplification coefficient of friction and local deviation coefficient K per meter.(2)The hanging basket cantilever construction stage:In the construction of concrete beam,loading age,super,vertical seam problem,different degrees of continuous rigid frame bridge span deflection and internal force of box girder influence.Among them,the impact of the largest super concrete.(3)It is recommended that all steel beams should be synchronized with the same construction stage to solve the prestress losses due to the tension of the steel beam.When the condition is not allowed,the prestress loss can be reduced by using the measure of the tension plate after the first tension web beam.For the subsequent construction of more stages,such as the beam section 0,The effective prestress of the design expectation of the bridge after the design of the bridge is obtained by appropriate amplification of the tension control stress.3,On the top of the pier beam zero detail analysis,simulation of prestressed steel beam loss value changes by 0%-10%-20% in the process of the pier top position,roof,web and floor space stress state comparative analysis.Effective evaluation should be the relationship between section of jacking force loss and pier stress.4,Combined with the prestressed concrete continuous rigid frame bridge flex cracking between relationship and control the influence factors of it in the construction stage and put forward control measures.For active control and eliminate cross beam deflection in the mid and body cracking and provide the basis of theoretical.