Study On Mechanical Behavior Of Steel Composite Beam In Deck Type Concrete-filled Steel Tubular Arch Bridge

The steel-concrete composite beam is composed of steel and concrete,which are connected by shear connectors.The overall performance of the structure after the combination of the two materials is obviously better than the simple superposition of the two materials.It is widely used in the long-span cable-stayed bridge,the steel-concrete composite beam bridge and the concrete-filled steel tube(CFST)arch bridge.When the steel-concrete composite beam is applied to the deck concrete-filled steel tubular arch bridge,the deformation of the main arch ring under the action of load and temperature affects the stress of the steel-concrete composite beam,which is different from other composite beams.In order to analyze the mechanical behavior of the composite beam in the deck concrete-filled steel tubular arch bridge,the following research work was carried out in this paper:1.From the point of view of stress and structural characteristics,the difference between the steel-concrete composite beams of the deck type CFST arch bridge and the steel-concrete composite beams of different bridge types is compared.Combined with the numerical model established in the preliminary design of a super long span bridge,the mechanical behaviors of the composite beams in elastic stage are obtained through the calculation comparison of the conversion section method and the stress analysis of the composite beams in the bridge under the construction stage and use stage.Design controlled by stress of the negative moment section of the composite beam of deck system is proposed.The influence of the temperature change and the shrinkage and creep of the steel tube arch on the composite beam of the deck system can be considered by increasing the calculated value of bending moment.2.In view of the horizontal slip and vertical uplift of the interface between the steel beam and the concrete slab caused by the use of flexible shear connectors,according to the load-slip relationship and the simplified axial tension theory,the slip and uplift stiffness are calculated.By using the finite element method,the distribution of slip and uplift of the composite beam of the deck system is revealed,and the influence of slip and uplift on the stress of the composite beam is studied through comparative analysis.Based on the research results of slip and uplift effect,and according to the distribution law of slip and uplift of the composite beam of the deck system,the reasonable arrangement form of shear connectors in the composite beam is proposed.3.After obtaining the mechanical characteristics of the composite beams of the deck concrete-filled steel tubular arch bridge,the design of the composite beam is studied.Based on the comparative analysis of the full continuous arrangement and split multi span arrangement of the composite beams in the deck system,the comparative analysis of the consolidation method and the support method between the composite beams of the deck system and the columns on the arch,the comparative analysis of different height ratio of concrete slab and steel beam in composite beam section,and the comparative analysis of different width thickness ratio of I-beam flange plate in composite beam section,relative design suggestions are put forward when the steel-concrete composite beam is used in the deck concrete-filled steel tube arch bridge.