Stress Characteristic Analysis Of The Wide Girder Of Extradosed Cable-stayed Bridge With Single Plane

Extradosed cable-stayed bridge is a new type of composite structure which have a rapid development in recent years. It is a new type of rigid and flexible bridge which is between beam bridge and cable-stayed bridge. For this structure, cables only share part of the load, there is a considerable part of the load from the bending and shearing girder.this type of bridge have characteristics of beam bridge and cable-stayed bridge,the girder stiffness of extradosed cable-stayed bridge is bigger,it not only resist the axial pressures,but also bear a considerable part of the moment and shear force. So its distribution of stress is rather complicated,the inhomogeneous phenomenon of spatial stress is very severe.The phenomenon of shear lag is more serious along with the increase of the span length and the transverse width of girder of the extradosed cable-stayed bridge and enlargement of width-span ratio and width height ratio. Anchorage force of cables focused on girder,which caused larger local stress in the vicinity of anchorage,then gradually spread whole deck,so deck of bridge existed serious phenomenon of shear lag. It is indicated that the structure is more effected by the shear lag of girder during the construction stages than completed bridge stage. The internal force of girder section under some stage during the construction stages is larger than completed bridge stage,so the internal force of the construction stages become design internal force of the control section. The girder of extradosed cable-stayed bridge mainly bears load, and cable bears partial load,stiffness of girder and cable tower is bigger,all kinds of structure systems and support systems and various parameter systems were designed as you like,so dynamic characteristics of each type of this bridge is different.Therefore,this text base on xijiang super large bridge in Jiang-Zhao Highway which is being built,finite element theory was adopted, space bar finite element model of whole bridge was established by Midas, global stress of girder was analyzed.Then the segmental finite element model of girder of anchorage zones which cable forces are applied to was established and spatial finite element analsis was carried out. Stress characteristics of wide girder under effect of cable were analyzed. Moreover,the normal stress of box section of broad width was calculated,The transmission angles of girder which cable forces are applied to were analyzed. Shear lag effect of wide girder of single cable plane extradosed cable-stayed bridge which cable forces were applied to was studied deeply, stress characteristics of girder were also considered on the completed bridge construction stage and the largest cantilever construction stage.The vibration mode and frequency were studied,stability of wind-resistant was verified on the completed bridge construction stage. Then variation of dynamic characteristics of this bridge was analyzed as the change of influence parameters. Specifically speaking, this paper has dealt with the following respects:1. Firstly, space bar finite element model of whole bridge was established by Midas, global stress of girder was analyzed on completed bridge stage.Then the segmental finite element model of girder of anchorage zones which cable forces were applied to was established, and spatial finite element analsis was carried out. Shear lag effect of wide girder which cable forces were applied to was studied on the completed bridge construction stage, distribution of shear lag coefficient of girder were also considered on the completed bridge construction stage,stress characteristics of wide girder under effect of cable were analyzed. Rationality and feasibility of design were verified.2. At first, finite element model of space bar was adopted so that whole stress of girder on the largest cantilever construction stage was analyzed.Then the spatial finite element model of segmental girder of anchorage zones which cable forces were applied to was established. The normal stress of box section of broad width was calculated,the transmission angles of girder which cable forces were applied to were analyzed. Moreover,the mechanical characteristics and shear lag effect of wide girder on the largest cantilever construction stage were studied. Rationality and feasibility of construction method that late poured band was set were verified.3. Finite element model of space bar was adopted,vibration mode and frequency were studied,stability of wind-resistant was verified on the completed bridge construction stage. Then variation of dynamic characteristics of this bridge was analyzed as the change of influence parameters.