| Prestressed concrete box girder bridge development up to now, has become one of the most commonly used bridge structure, but in the box girder cracking phenomena exist generally, many set up transverse prestressed box girder bridge is still produce the longitudinal cracks in the roof, this shows that the transverse prestress setting design did not achieve the desired effect.The longitudinal prestress under the influence of poisson effect to the transverse impact of roof, and the weaken effect to the transverse prestressing by box girder webs, this has certain guiding significance to longitudinal cracks in preventing roofIn this paper, in view of the poisson effect and the framework effect to the transverse stress on the roof, Applied finite element software Midas fea to establish solid model,and use DouXia bridge as the engineering background.Through the lateral position of prestressed tensioning roof beam to study the transverse impact of poisson’s effect on the roof, and transverse stress distribution;Through tensioning prestressed beam at different location of the vertical longitudinal web to study the effect of the frame and poisson effect under the action of the transverse impact of roof and the transverse stress distribution rule.At the same time, according to the DouXia bridge’s actual drawings to calculate the accumulative transverse stress along the longitudinal in the center of the roof from the segments No.0to midspan, study the cumulative effect of longitudinal prestressing, research the cumulative effect’s distribution produced by transverse stressFinally, studied the weaken effect of box girder webs to the transverse prestressing, and connecting with the weight of box girder, vehicle load and longitudinal prestressing produced transverse stress on roof to study whether the transverse prestress reserve stress value can resist longitudinal cracks of roof, layout and design of transverse prestress and proposed the prevention of longitudinal cracks... |
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