Mechanical And Aerodynamic Property Of Self-anchored Suspension Bridge With Twin Decks In Tandem

Self-anchored suspension bridge anchors its main cable to the main deck to save from huge anchorages. It first occurred in the end of 19th century, and then quickly developed in western countrys because of its beautiful shape and adaptability of bad geological conditions. At the beginning of 20th century, Konohana Bridge in Japan and Yeongjong Bridge in South Korea which stands for the modern self-anchored suspension bridges were built. Meanwhile, self-anchored suspension bridges were widely built within China. For now, the research works are limited within cable shape analysis, static and dynamic property analysis, which is not enough. In this thesis, the study focuses on the mechanical properties, redundancy properties and etc of self-anchored suspension bridge.With a project background of National Natural Science Fund (50608030), this thesis made researches on the effects of aerodynamic interference on aerostatic coefficients of the twin decks in tandem of large-span bridges. Due to short distance between twin decks, this kind of bridge suffers from the aerodynamic interference between the two decks. For example, the vortex-excited resonance, flutter stability and the wind load of the upper and lower decks, which are all caused by the aerodynamic interference between the two parallel decks. The aerodynamic response is one of the issues that get great concern during designing of large span bridges with twin decks. This thesis carried out to investigate the affection of a changing twin deck net distance on the aerostatic coefficients of twin decks.Based on the project of Forshan Pingsheng Bridge in Guangdong, a single pylon self-anchored suspension bridge with twin decks and the research project of aerodynamic interference effect on large span bridges with twin decks in tandem, the following resesrch works were carried out:Verify the precision of the main cable shape-finding program based on the segmental catenary theory. Finite elemental analysis model is established. Parameters of the single-span and double-span self-anchored suspension bridges were investigated. Through the comparison of the affection of sag ratio and side-main span ratio to the property of self-anchored suspension bridge, it concluded the affection of sag ratio and side-main span ratio on the main deck axial force, the upward force of the bearing and the displacement of the main deck. Redundancy analysis of self-anchored suspension bridge was carried out. Through the comparison of the affection of failure hanger and stiffness reduce of the main deck on the property of structure, it concludes the changing law of main cable force, the upward force of the bearing and first-order dynamic feature of the main deck displacement under the circumstance of a break hanger and reduce of main deck stiffness.The background of aerodynamic interference analysis is National Natural Science Fund. Wind tunnel test was carried out to investigate the effects on aerostatic coefficients of twin decks by changing the net distance of twin decks. Then the numerical simulations of aerodynamic interference effects on twin decks in tandem for difference net distances between of the twin decks were carried out with help of CFX, which is commercial software for computational fluid dynamic. The results from numerical simulations were compared with the ones from the wind tunnel test.