Research on the Key Technology of Hybrid Beam Cable-stayed Bridge with Limit Side Mid-span Ratio

Taking the main span of 716 meters mixed girder cable-stayed bridge (side mid-span ratio 0.251) as an example, the key technologies such as fully floating and semi-floating structure system, the position of steel-concrete combined section, and the use of thick slab concrete and iron sand concrete for side span weight are studied. The results show that :(1) As for the main girder, the bending moment at the column of the full-wave scheme is only 36.4% of that of the semi-wave scheme, and the bending moment of the stiffened girder in other areas is the same as that of the semi-wave scheme. In terms of main beam stiffness, there is little difference between full - floating scheme and semi-floating scheme. (2) In the completed bridge state, the longitudinal bending moment of the joint section located at the middle span is far greater than that of the side-span scheme, and the dead load bending moment distribution of the main girder is not ideal. Under the operation condition, the longitudinal bending moment of the main girder of the two schemes is roughly the same under live load. In terms of supporting reaction force, the joint section is located at the middle span, and the supporting reaction force of the auxiliary pier near the bridge tower is far greater than that of the side-span scheme. (3) The thick slab concrete design can not only ensure that the bridge and the construction state of the side span of the fulcrum are not negative reaction and under pressure, but also has no pressure to fix measures, simplify the construction process, convenient later inspection and maintenance.