Research On Static Behavior Of Channel Girder And Steel Truss Composite Bridge In Rail Transit

The channel girder and steel truss composite bridge is a new type of steel-concrete composite bridges, which has the advantages on low construction height and strong noise reduction ability of channel girder bridges as well as advantages on light weight and easy construction of truss girder bridges. This composite structure has potentially broad application in overpass bridges of urban rail transit. Currently, studies of the composite bridges are not yet mature and researches on composite joints are still at preliminary stage. In this dissertation, a finite element analysis of full-bridge mechanical performance, sensitivities of design parameters, shear lag effect and truss composite joints was carried out. The main contents are presented as follows.(1)The development and research status of channel girder bridges, through truss bridges and composite channel girder bridges were reviewed. The shortages during the researches on channel girder and steel truss composite bridges were summarized, and the research significance of this dissertation was put forward.(2)The internal forces analysis theories of complex structure bridge were discussed, and the various parameter models used in the paper were determined.(3)Analyses of static behavior of channel girder and steel truss composite bridge under three different load conditions were created by ANSYS, and the feasibility of the structure was verified. The effect of changing structure design parameters on this type of composite bridge was studied, and the recommendations of design parameters were given. It suggests that the high span ratio can be controlled at 1/5.5, the vertical bars do not need to be added., the thickness of the crossbeams can be controlled within the range of 0.7-0.85m, and the main beam height can be adjusted according to safety reserve of truss members.(4)The shear lag effects of channel girder bridge with and without crossbeams as well as the channel girder bridges with and without steel truss were compared. The results show that the crossbeams can improve the shear lag effect of the section, but it has no obvious improvement to the shear lag effect of other sections. And the shear lag effect is only related to the section structure of the channel girder bridge. When the channel girder as a bending member is combined with other components to form a new structure, its shear lag effect is basically not affected.(5)The nonlinearity of the ear plate truss composite joint was analyzed by ANSYS. The ultimate bearing capacity, stress distribution, and cracks development law of the composite joint were studied.In this paper, the research contents and conclusions can provide some theoretical support and technical references in a certain extent for channel girder and steel truss composite bridges in urban rail transit.