Overall Design and Key Techniques of Zangke River Bridge of Nayong-Qinglong Expressway
The main bridge of Zangke River Bridge of the Nayong-Qinglong Expressway is a suspension bridge with a main suspended span of 1 080 m,featuring a restraint system that includes longitudinal viscous dampers with low damping exponent,lateral elastic wind-resistant bearings,midspan flexible central buckle,stabilizing cables linked to main cables in the side spans,and the vertical connecting rods in towers.The stiffening girder consists of steel trusses that act compositely with the overlaid orthotropic steel deck panels.The towers are portal-frame concrete structures,where the two columns of each tower rest on individual pile caps that are supported by end-bearing piles with a diameter of 3.8 m.The main cables,which are composed of high-strength galvanized aluminum-rare earth alloy steel wires with a nominal tensile strength of 1 960 MPa,are arranged in three spans of 265,1 080 and 435 m.The hanger cables,flexible central buckles and stabilizing cables are made of galvanized aluminum-rare earth alloy steel wires with a tensile strength of 1 960 MPa,the steel wires of each cable are wrapped with three layers of steel Z wires to be locked coil cables with better durability and fatigue resistance.The stabilizing cables linked to the main cables in the side spans effectively limit the vertical displacement of the side-span main cables under live loads.By taking effective use of the tenon and rock clamping effect,the engineering quantity of the Nayong-side gravity anchorage composite with rock footing was reduced by about 20％.The erection of the stiffening girder was conducted smoothly in the limited space of the valley,with no assistance of lifting platform.
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