Analysis On Spatial Effects For Multi-Room Curved Box-Girders Based On Beam Element

The promoting of the development of urbanization increases the city traffic flow. The increased traffic flow in road design put forward some new requirements for the bridges in the road line. The curved bridge is an important part in city bridge and accounts for a large proportion of urban elevated bridges. The linking effect of curved bridge makes each direction a whole.The curved bridge has more complicated mechanical characteristics, multiple spatial effects than the linear bridge. Box girder structure will generate torque in addition to bending moment and shear force, even if it is under asymmetric load. Excessive torque effect will produce diagonal cracks near the bridge support positions. This will lead to curved bridge’s structural safety performance reduced.Except for the prominent characteristics of torsional effect, each web of the multi-room curved box girder having unbalanced force for asymmetric loading is also it’s main feature.The complexity of box girder structure of force transmission leads to the ultimate stress calculation results of curved box-girder have a quite different from the rdinary straight box-girder structure. Based on the above, this thesis carries out the following research work:1, Curved box-girder birdge usually sets powerful crossbeam structure in the pivot position.The presence of crossbeam makes the curved beam structure presented as a constraint torsion beam structure status.The curved box-girder bridge will have additional warping bimoment, freedom and constraint torque under restrained torsion effect. In this thesis, the effects of internal force on bridge restrained torsion caused by the weight load and vehicle load are calculated. Besids, the factors of radius and width of curved bridge, whiche have influence on restrained torsion, are also have been analysed.2, Curved beam structures have a more complex effect under the asymmetric load.This thesis analyses asymmetric characteristic caused by the weight load and vehicle load, by using different method and defining different ratio coefficient.At last the factors of radius and asymmetric distance of vehicle load, whiche have influence on asymmetric effect,are also have been analysed.3, The complexed mechanical properties of curved box-girder makes it difficult to get an accurate stress result under external loads. The calculation results often do not reflect the real state of stress by simply using stress calculation methods for ordinary straight beam to calculate multi-room curved box-girder bridge.More refine effects results could be get by using spatial grid model.