Extension of bridging capacity of cable-supported bridges using double main spans or twin parallel decks solutions

摘要

Technical investigation of current bridging capacity of cable-supported bridges shows that its single main span is up to 2 kilometres for suspension bridge and 1 kilometre for cable-stayed bridge respectively with the total deck width of about 40 metres. Approaches to extend bridging capacity by utilising double main span suspension structure and twin parallel deck cable-stayed structure are introduced. Special emphasis is placed on longitudinal stiffness design of central pylon for double main span suspension bridge. Both inversed Y-shaped pylons in Jiangsu Taizhou Bridge and I-shaped pylon with fixed connection of deck and central pylon in Anhui Maanshan Bridge can provide proper longitudinal stiffness for the central pylon. Two types of pylon and three kinds of deck section have been checked in the early design stage for a twin parallel deck cable-stayed bridge called Ningbo Yongjiang Bridge. Finally, a composite cross section with two diamond pylon has been decided on when considering structural durability.