Study On Support System And Span Ratio Of Curved Steel Box Girder Bridge

Curved steel box girder bridge has many unique advantages,such as good overallperformance,excellent torsional resistance,convenient construction and so on.With the rapid development of China's economy and steel overcapacity,under the guidance of the state,in some areas with special requirements,curved steel box girder bridge has a good prospect of development.The research of curved steel box girder bridge has made a lot of progress,but there are still no corresponding guidelines in Our country.The disasters of curved bridge under the supporting system of curved bridge happen from time to time,such as girder climbing,overturning and so on.On the basis of existing studies,this paper studies the deformationmechanism of curved steel box girder bridge,the reasonable supporting system of curved steel box girder bridge and the reasonable ratio of mid-span and span of the side.The specificresearch contents are as follows:1.The research background of curved steel box girder bridge is introduced in detail.The research and development status of curved steel box girder bridge at home and abroad issummarized.And get the deformation mechanism of the structure under temperature load effect:the end of the system temperature and positive temperature gradient effect will be made by the bridge beam body center to expand on both ends of the bridge,the system temperature decrease and the negative temperature gradient effect will make the beam by the contraction to bridge center on both ends of the bridge,in the opposite direction,the displacement curve of idealconstraints deformation of steel box girder bridge is composed of radial displacement and tangential displacement.2.Analyze the stress changes of curved steel box girder bridge under the commonly used full torsion resistance supporting system and the improved supporting system,and analyze the sensitivity of curved steel box girder bridge to the horizontal stiffness of different supports.It is found that the improved supporting system can effectively relax the radial deformation capacity of the structure,so that the structure bending moment M_z,horizontal support reaction force,stress and other aspects are greatly improved.That is,the reasonable curved steel box girder bridge support system is:four side pier supports only constrain radial(transverse bridge)displacement,one middle pier support can move in both directions,the other middle piersupport only restricts tangential(along the bridge)displacement,the corner of all supports is relaxed,and the pin axis is arranged at the center line of the bridge to limit the displacement.The supporting system adopts movable support,provides horizontal constraint with pin shaft,sets limit block horizontally at side pier,and matches with finite displacement support with tangential pin shaft.In order to allow a small displacement of the support under the action of temperature and shrinkage,the reserved deformation of the support is designed according to the expansion and shrinkage displacement of the beam.Under the action of earthquake,it can limit the beam position and prevent the movable support with finite displacement from falling beam.3.In this paper,through the establishment of 7 groups of different edge across the span ratio of space finite element model,this paper compares and analyzes the comprehensiveconsideration on both inner side and outside of the balanced side pier bearing vertical reaction force,lower pier bearing vertical reaction,equilibrium in the largest bearing horizontaldisplacement,the smaller the positive and negative bending(torque)peak,reach the purpose of optimizing structure internal force,found that the curve of steel box girder bridge across the span ratio of 0.86 is more reasonable.