Conceptual Design of Superspan Partial Ground-Anchored Cable-Stayed Bridge with Crossing Stay Cables

摘要

As the span of conventional cable-stayed bridges reaches 1,200 m or longer, accumulated horizontal force components of the stay cables cause huge axial pressure in the girder, leading to sharp increases of girder dimension and weight, which makes it difficult to compete with suspension bridges in terms of economic consideration. In this paper, a new type of cable-stayed bridge is proposed, namely the partial ground-anchored cable-stayed bridge with crossing stay cables. In this new cable-stayed bridge system, long stay cables cross with each other in the midspan zone of the main span while the other ends of the long cables are anchored to the ground in the side spans. By this design, the long cables result in no additional horizontal pressure to the main girder, and the ratio of pylon height to span length can be reduced. A comparative analysis of this new bridge system with a conventional self-anchored cable-stayed bridge with a main span of 1,408 m is carried out. Results show that by using the new bridge system, the horizontal pressure in the main girder can be reduced by 29.6%, and the total cost can be reduced by 11.8%. Furthermore, the size of ground anchors for this new bridge system is only about 30% of that of a suspension bridge with the same span length. Finally, a cantilever construction method for the new bridge system is introduced as well.