On the morning of March 20th, after nearly 4 hours of precise adjustment and locking, the key control project Gaolangang Bridge on the Huangmaohaixia Cross-Sea Corridor successfully achieved closure. This is the first of the two main bridges on the project to close, marking a major breakthrough in the superstructure construction.
The Gaolangang Bridge adopts a fully floating system separated steel box girder structure, with a total of 97 girder segments. The box girder is 4 meters high, with a total width of 50.4 meters for the dual-span bridge deck. The standard segment length is 15 meters, with a hoisting height of about 70 meters. The weight of a single standard girder segment is 370 tons, and the total weight of the steel girders is 35,877 tons, equivalent to the weight of more than 11,700 small cars. The pier cap blocks of the bridge were hoisted by the 3,600-ton beam erection vessel “Daqinghaiyou,” while the remaining segments were erected using a 2×250-ton beam erection machine in a balanced cantilever method.
To reduce structural dead load and improve aerodynamic performance, the main girders of the Gaolangang Bridge adopt a segmented steel box girder design, with the box sections connected by a central transverse beam, resembling a dumbbell shape. This results in the characteristics of “heavier at both ends and lighter in the middle” and “weaker rigidity in the middle,” which poses a challenge for deformation control during the hoisting stage. The project construction personnel conducted multiple discussions and simulation calculations, and decided to weld positioning plates onto the outer webs of the steel box girders to fix the two ends, while optimizing the matching temporary works and welding sequence. After the adjustments, the construction profile and monitoring profile achieved a deviation within 10 millimeters, realizing high-precision closure.
Currently, the Huangmaohaixia Cross-Sea Corridor project is progressing smoothly. All five main towers of the Huangmaohai Bridge and Gaolangang Bridge have been capped, the Gaolangang Bridge has completed closure, and the Shishan Tunnel and Xiangshan Tunnel have both been bored through. For the Huangmaohai Bridge, 30 segments of the steel box girders have been erected for both the east and west towers, while 21 segments have been completed for the central tower. The main structure of the bridge is expected to be completed by the end of this year.