Qinglong Isle Bridge, Yiyang, China: a lightweight composite-girder self-anchored suspension bridge

The Qinglong Isle Bridge is the world’s first self-anchored suspension bridge with a composite stiffening girder constructed using a steel double-box and ultra-high-performance concrete (UHPC). The bridge deck of the composite girder consists of a thin panel (10 cm thick) and longitudinal ribs (12 cm thick) and was constructed using UHPC with a high bending strength and high-durability. The self-weight of the UHPC deck is approximately 30% less than that of the deck of an ordinary concrete composite girder. This reduced self-weight leads to reduced work for other primary structures in the bridge. To improve the crack resistance of the cast-in-place (CiP) joints between the precast deck slabs, an innovative T-shaped design was adopted for the joints and CiP UHPC was subjected to high-temperature steam curing, which reduces the shrinkage and creep effect of UHPC materials in operation. The extensive use of UHPC materials in China has resulted in a gradual reduction in the overall unit price, thereby enhancing the economic viability of steel–UHPC composite girder in construction. Furthermore, the UHPC structure exhibits superior durability, which markedly diminishes the maintenance expenses associated with the bridge throughout its operational lifespan. In comparison with conventional concrete composite girders, steel–UHPC composite girders provide substantial life cycle cost savings.