Abstract:Taking a non-closed upper and lower chord combined force-bearing steel truss arch bridge with a span of 204 m as an example, the overall design and structural design essentials of the bridge are introduced in detail. The longitudinal and transverse force transmission mechanisms of this type of arch bridge are studied. And the selection principles of key design parameters such as rise to span ratio, section size, plate thickness and wind support arrangement are clarified. The research results show that for the non-closed upper and lower chord combined force-bearing steel truss arch bridges, the upper and lower chord arch ribs are mainly subjected to the compression, which present the obvious force-bearing characteristics of truss beam. As the rise to span ratio decreases, the compressive stress of the upper and lower arch ribs and the tensile stress of the tie beam gradually increase. In the structural design, the axial compression stiffness can be determined according to the relative relationship between the axial pressures borne by the upper and lower chord arch ribs and the control section of the tie beam in the ultimate bearing capacity state, and then the cross-sectional dimensions and plate thicknesses are selected. The number and location of wind braces are mainly controlled by the lateral forces under the action of crosswind loads. When designing the similar projects, the lateral forces under different wind brace arrangements can be calculated first, and then the lateral stability of the bridge can be further verified. The research conclusion can provide reference for the design of the similar bridge structure.
